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| -rw-r--r-- | docs/cgi/cl.html | 46 | ||||
| -rw-r--r-- | docs/cgi/env.html | 149 | ||||
| -rw-r--r-- | docs/cgi/in.html | 33 | ||||
| -rw-r--r-- | docs/cgi/interface.html | 29 | ||||
| -rw-r--r-- | docs/cgi/out.html | 126 | ||||
| -rw-r--r-- | docs/draft-coar-cgi-v11-03-clean.html | 2674 |
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diff --git a/docs/cgi/cl.html b/docs/cgi/cl.html new file mode 100644 index 000000000..5779d623e --- /dev/null +++ b/docs/cgi/cl.html @@ -0,0 +1,46 @@ +<html><head><title>CGI Command line options</title></head><body><h1><img alt="" src="cl_files/CGIlogo.gif"> CGI Command line options</h1> +<hr> <p> + +</p><h2>Specification</h2> + +The command line is only used in the case of an ISINDEX query. It is +not used in the case of an HTML form or any as yet undefined query +type. The server should search the query information (the <code>QUERY_STRING</code> environment variable) for a non-encoded += character to determine if the command line is to be used, if it +finds one, the command line is not to be used. This trusts the clients +to encode the = sign in ISINDEX queries, a practice which was +considered safe at the time of the design of this specification. <p> + +For example, use the <a href="http://hoohoo.ncsa.uiuc.edu/cgi-bin/finger">finger script</a> and the ISINDEX interface to look up "httpd". You will see that the script will call itself with <code>/cgi-bin/finger?httpd</code> and will actually execute "finger httpd" on the command line and output the results to you. +</p><p> +If the server does find a "=" in the <code>QUERY_STRING</code>, +then the command line will not be used, and no decoding will be +performed. The query then remains intact for processing by an +appropriate FORM submission decoder. +Again, as an example, use <a href="http://hoohoo.ncsa.uiuc.edu/cgi-bin/finger?httpd=name">this hyperlink</a> to submit <code>"httpd=name"</code> to the finger script. Since this <code>QUERY_STRING</code> +contained an unencoded "=", nothing was decoded, the script didn't know +it was being submitted a valid query, and just gave you the default +finger form. +</p><p> +If the server finds that it cannot send the string due to internal +limitations (such as exec() or /bin/sh command line restrictions) the +server should include NO command line information and provide the +non-decoded query information in the environment +variable <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html#query"><code>QUERY_STRING</code></a>. </p><p> +</p><hr> +<h2>Examples</h2> + +Examples of the command line usage are much better <a href="http://hoohoo.ncsa.uiuc.edu/cgi/examples.html">demonstrated</a> than explained. For these +examples, pay close attention to the script output which says what +argc and argv are. <p> + +</p><hr> + +<a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="cl_files/back.gif">Return to the +interface specification</a> <p> + +CGI - Common Gateway Interface +</p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address> + + +</body></html>
\ No newline at end of file diff --git a/docs/cgi/env.html b/docs/cgi/env.html new file mode 100644 index 000000000..961671aaa --- /dev/null +++ b/docs/cgi/env.html @@ -0,0 +1,149 @@ +<html><head><title>CGI Environment Variables</title></head><body><h1><img alt="" src="env_files/CGIlogo.gif"> CGI Environment Variables</h1> +<hr> + +<p> + +In order to pass data about the information request from the server to +the script, the server uses command line arguments as well as +environment variables. These environment variables are set when the +server executes the gateway program. </p><p> + +</p><hr> +<h2>Specification</h2> + + <p> +The following environment variables are not request-specific and are +set for all requests: </p><p> + +</p><ul> +<li> <code>SERVER_SOFTWARE</code> <p> + + The name and version of the information server software answering + the request (and running the gateway). Format: name/version </p><p> + +</p></li><li> <code>SERVER_NAME</code> <p> + The server's hostname, DNS alias, or IP address as it would appear + in self-referencing URLs. </p><p> + +</p></li><li> <code>GATEWAY_INTERFACE</code> <p> + The revision of the CGI specification to which this server + complies. Format: CGI/revision</p><p> + +</p></li></ul> + +<hr> + +The following environment variables are specific to the request being +fulfilled by the gateway program: <p> + +</p><ul> +<li> <a name="protocol"><code>SERVER_PROTOCOL</code></a> <p> + The name and revision of the information protcol this request came + in with. Format: protocol/revision </p><p> + +</p></li><li> <code>SERVER_PORT</code> <p> + The port number to which the request was sent. </p><p> + +</p></li><li> <code>REQUEST_METHOD</code> <p> + The method with which the request was made. For HTTP, this is + "GET", "HEAD", "POST", etc. </p><p> + +</p></li><li> <code>PATH_INFO</code> <p> + The extra path information, as given by the client. In other + words, scripts can be accessed by their virtual pathname, followed + by extra information at the end of this path. The extra + information is sent as PATH_INFO. This information should be + decoded by the server if it comes from a URL before it is passed + to the CGI script.</p><p> + +</p></li><li> <code>PATH_TRANSLATED</code> <p> + The server provides a translated version of PATH_INFO, which takes + the path and does any virtual-to-physical mapping to it. </p><p> + +</p></li><li> <code>SCRIPT_NAME</code> <p> + A virtual path to the script being executed, used for + self-referencing URLs. </p><p> + +</p></li><li> <a name="query"><code>QUERY_STRING</code></a> <p> + The information which follows the ? in the <a href="http://www.ncsa.uiuc.edu/demoweb/url-primer.html">URL</a> + which referenced this script. This is the query information. It + should not be decoded in any fashion. This variable should always + be set when there is query information, regardless of <a href="http://hoohoo.ncsa.uiuc.edu/cgi/cl.html">command line decoding</a>. </p><p> + +</p></li><li> <code>REMOTE_HOST</code> <p> + The hostname making the request. If the server does not have this + information, it should set REMOTE_ADDR and leave this unset.</p><p> + +</p></li><li> <code>REMOTE_ADDR</code> <p> + The IP address of the remote host making the request. </p><p> + +</p></li><li> <code>AUTH_TYPE</code> <p> + If the server supports user authentication, and the script is + protects, this is the protocol-specific authentication method used + to validate the user. </p><p> + +</p></li><li> <code>REMOTE_USER</code> <p> + If the server supports user authentication, and the script is + protected, this is the username they have authenticated as. </p><p> +</p></li><li> <code>REMOTE_IDENT</code> <p> + If the HTTP server supports RFC 931 identification, then this + variable will be set to the remote user name retrieved from the + server. Usage of this variable should be limited to logging only. + </p><p> + +</p></li><li> <a name="ct"><code>CONTENT_TYPE</code></a> <p> + For queries which have attached information, such as HTTP POST and + PUT, this is the content type of the data. </p><p> + +</p></li><li> <a name="cl"><code>CONTENT_LENGTH</code></a> <p> + The length of the said content as given by the client. </p><p> + +</p></li></ul> + + +<a name="headers"><hr></a> + +In addition to these, the header lines received from the client, if +any, are placed into the environment with the prefix HTTP_ followed by +the header name. Any - characters in the header name are changed to _ +characters. The server may exclude any headers which it has already +processed, such as Authorization, Content-type, and Content-length. If +necessary, the server may choose to exclude any or all of these +headers if including them would exceed any system environment +limits. <p> + +An example of this is the HTTP_ACCEPT variable which was defined in +CGI/1.0. Another example is the header User-Agent.</p><p> + +</p><ul> +<li> <code>HTTP_ACCEPT</code> <p> + The MIME types which the client will accept, as given by HTTP + headers. Other protocols may need to get this information from + elsewhere. Each item in this list should be separated by commas as + per the HTTP spec. </p><p> + + Format: type/subtype, type/subtype </p><p> + + +</p></li><li> <code>HTTP_USER_AGENT</code><p> + + The browser the client is using to send the request. General +format: <code>software/version library/version</code>.</p><p> + +</p></li></ul> + +<hr> +<h2>Examples</h2> + +Examples of the setting of environment variables are really much better +<a href="http://hoohoo.ncsa.uiuc.edu/cgi/examples.html">demonstrated</a> than explained. <p> + +</p><hr> + +<a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="env_files/back.gif">Return to the +interface specification</a> <p> + +CGI - Common Gateway Interface +</p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address> + +</body></html>
\ No newline at end of file diff --git a/docs/cgi/in.html b/docs/cgi/in.html new file mode 100644 index 000000000..679306aaa --- /dev/null +++ b/docs/cgi/in.html @@ -0,0 +1,33 @@ +<html><head><title>CGI Script input</title></head><body><h1><img alt="" src="in_files/CGIlogo.gif"> CGI Script Input</h1> +<hr> + +<h2>Specification</h2> + +For requests which have information attached after the header, such as +HTTP POST or PUT, the information will be sent to the script on stdin. +<p> + +The server will send <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html#cl">CONTENT_LENGTH</a> bytes on +this file descriptor. Remember that it will give the <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html#ct">CONTENT_TYPE</a> of the data as well. The server is +in no way obligated to send end-of-file after the script reads +<code>CONTENT_LENGTH</code> bytes. </p><p> +</p><hr> +<h2>Example</h2> + +Let's take a form with METHOD="POST" as an example. Let's say the form +results are 7 bytes encoded, and look like <code>a=b&b=c</code>. +<p> + +In this case, the server will set CONTENT_LENGTH to 7 and CONTENT_TYPE +to application/x-www-form-urlencoded. The first byte on the script's +standard input will be "a", followed by the rest of the encoded string.</p><p> + +</p><hr> + +<a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="in_files/back.gif">Return to the +interface specification</a> <p> + +CGI - Common Gateway Interface +</p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address> + +</body></html>
\ No newline at end of file diff --git a/docs/cgi/interface.html b/docs/cgi/interface.html new file mode 100644 index 000000000..33f02881b --- /dev/null +++ b/docs/cgi/interface.html @@ -0,0 +1,29 @@ +<html><head><title>The Common Gateway Interface Specification +[http://hoohoo.ncsa.uiuc.edu/cgi/interface.html] +</title></head><body><h1><img alt="" src="interface_files/CGIlogo.gif"> The CGI Specification</h1> + +<hr> + +This is the specification for CGI version 1.1, or CGI/1.1. Further +revisions of this protocol are guaranteed to be backward compatible. +<p> + +The server and the CGI script communicate in four major ways. Each of +the following is a hotlink to graphic detail.</p><p> + +</p><ul> +<li> <a href="env.html">Environment variables</a> +</li><li> <a href="cl.html">The command line</a> +</li><li> <a href="in.html">Standard input</a> +</li><li> <a href="out.html">Standard output</a> +</li></ul> +<hr> + + +<a href="http://hoohoo.ncsa.uiuc.edu/cgi/overview.html"><img alt="[Back]" src="interface_files/back.gif">Return to the overview</a> <p> + + + +CGI - Common Gateway Interface +</p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address> +</body></html>
\ No newline at end of file diff --git a/docs/cgi/out.html b/docs/cgi/out.html new file mode 100644 index 000000000..2203ee5a0 --- /dev/null +++ b/docs/cgi/out.html @@ -0,0 +1,126 @@ +<html><head><title>CGI Script output</title></head><body><h1><img alt="" src="out_files/CGIlogo.gif"> CGI Script Output</h1> +<hr> + +<h2>Script output</h2> + +The script sends its output to stdout. This output can either be a +document generated by the script, or instructions to the server for +retrieving the desired output. <p> +</p><hr> + +<h2>Script naming conventions</h2> + +Normally, scripts produce output which is interpreted and sent back to +the client. An advantage of this is that the scripts do not need to +send a full HTTP/1.0 header for every request. <p> +<a name="nph"> +Some scripts may want to avoid the extra overhead of the server +parsing their output, and talk directly to the client. In order to +distinguish these scripts from the other scripts, CGI requires that +the script name begins with nph- if a script does not want the server +to parse its header. In this case, it is the script's responsibility +to return a valid HTTP/1.0 (or HTTP/0.9) response to the client. </a></p><p> + +</p><hr> +<h2><a name="nph">Parsed headers</a></h2> + +<a name="nph">The output of scripts begins with a small header. This header consists +of text lines, in the same format as an </a><a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/Object_Headers.html"> +HTTP header</a>, terminated by a blank line (a line with only a +linefeed or CR/LF). <p> + +Any headers which are not server directives are sent directly back to +the client. Currently, this specification defines three server +directives:</p><p> + +</p><ul> +<li> <code>Content-type</code> <p> + + This is the MIME type of the document you are returning. </p><p> + +</p></li><li> <code>Location</code> <p> + + This is used to specify to the server that you are returning a + reference to a document rather than an actual document. </p><p> + + If the argument to this is a URL, the server will issue a redirect + to the client. </p><p> + + If the argument to this is a virtual path, the server will + retrieve the document specified as if the client had requested + that document originally. ? directives will work in here, but # + directives must be redirected back to the client.</p><p> + + +</p></li><li> <a name="status"><code>Status</code></a><p> + + This is used to give the server an HTTP/1.0 <a href="http://www.w3.org/hypertext/WWW/Protocols/HTTP/HTRESP.html">status +line</a> to send to the client. The format is <code>nnn xxxxx</code>, +where <code>nnn</code> is the 3-digit status code, and +<code>xxxxx</code> is the reason string, such as "Forbidden".</p><p> + +</p></li></ul> + +<hr> +<h2>Examples</h2> + +Let's say I have a fromgratz to HTML converter. When my converter is +finished with its work, it will output the following on stdout (note +that the lines beginning and ending with --- are just for illustration +and would not be output): <p> + +</p><pre>--- start of output --- +Content-type: text/html + +--- end of output --- +</pre> + +Note the blank line after Content-type. <p> + +Now, let's say I have a script which, in certain instances, wants to +return the document <code>/path/doc.txt</code> from this server just +as if the user had actually requested +<code>http://server:port/path/doc.txt</code> to begin with. In this +case, the script would output: </p><p> +</p><pre>--- start of output --- +Location: /path/doc.txt + +--- end of output --- +</pre> + +The server would then perform the request and send it to the client. +<p> + +Let's say that I have a script which wants to reference our gopher +server. In this case, if the script wanted to refer the user to +<code>gopher://gopher.ncsa.uiuc.edu/</code>, it would output: </p><p> + +</p><pre>--- start of output --- +Location: gopher://gopher.ncsa.uiuc.edu/ + +--- end of output --- +</pre> + +Finally, I have a script which wants to talk to the client directly. +In this case, if the script is referenced with <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html#protocol"><code>SERVER_PROTOCOL</code></a> of HTTP/1.0, +the script would output the following HTTP/1.0 response: <p> + +</p><pre>--- start of output --- +HTTP/1.0 200 OK +Server: NCSA/1.0a6 +Content-type: text/plain + +This is a plaintext document generated on the fly just for you. + +--- end of output --- +</pre> + + +<hr> + +<a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html"><img alt="[Back]" src="out_files/back.gif">Return to the +interface specification</a> <p> + +CGI - Common Gateway Interface +</p><address><a href="http://hoohoo.ncsa.uiuc.edu/cgi/mailtocgi.html">cgi@ncsa.uiuc.edu</a></address> +</body></html>
\ No newline at end of file diff --git a/docs/draft-coar-cgi-v11-03-clean.html b/docs/draft-coar-cgi-v11-03-clean.html new file mode 100644 index 000000000..37835500c --- /dev/null +++ b/docs/draft-coar-cgi-v11-03-clean.html @@ -0,0 +1,2674 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" + "http://www.w3.org/TR/REC-html40/loose.dtd"> +<HTML> + <HEAD> + <TITLE>Common Gateway Interface - 1.1 *Draft 03* [http://cgi-spec.golux.com/draft-coar-cgi-v11-03-clean.html] + </TITLE> +<!--#if expr="$HTTP_USER_AGENT != /Lynx/" --> + <!--#set var="GUI" value="1" --> +<!--#endif --> + <LINK HREF="mailto:Ken.Coar@Golux.Com" rev="revised"> + <LINK REL="STYLESHEET" HREF="cgip-style-rfc.css" TYPE="text/css"> + <META name="latexstyle" content="rfc"> + <META name="author" content="Ken A L Coar"> + <META name="institute" content="IBM Corporation"> + <META name="date" content="25 June 1999"> + <META name="expires" content="Expires 31 December 1999"> + <META name="document" content="INTERNET-DRAFT"> + <META name="file" content="<draft-coar-cgi-v11-03.txt>"> + <META name="group" content="INTERNET-DRAFT"> +<!-- + There are a lot of BNF fragments in this document. To make it work + in all possible browsers (including Lynx, which is used to turn it + into text/plain), we handle these by using PREformatted blocks with + a universal internal margin of 2, inside one-level DL blocks. + --> + </HEAD> + <BODY> + <!-- + HTML doesn't do paper pagination, so we need to fake it out. Basing + our formatting upon RFC2068, there are four (4) lines of header and + four (4) lines of footer for each page. + +<DIV ALIGN="CENTER"> + <PRE> + + + + +Coar, et al. CGI/1.1 Specification May, 1998 +INTERNET-DRAFT Expires 1 December 1998 [Page 2] + + + </PRE> +</DIV> + --> + <!-- + The following weirdness wrt non-breaking spaces is to get Lynx + (which is barely TABLE-aware) to line the left/right justified + text up properly. + --> + <DIV ALIGN="CENTER"> + <TABLE WIDTH="100%" CELLPADDING=0 CELLSPACING=0> + <TR VALIGN="TOP"> + <TD ALIGN="LEFT"> + INTERNET-DRAFT + </TD> + <TD ALIGN="RIGHT"> + Ken A L Coar + </TD> + </TR> + <TR VALIGN="TOP"> + <TD ALIGN="LEFT"> + draft-coar-cgi-v11-03.{html,txt} + </TD> + <TD ALIGN="RIGHT"> + IBM Corporation + </TD> + </TR> + <TR VALIGN="TOP"> + <TD ALIGN="LEFT"> + + </TD> + <TD ALIGN="RIGHT"> + D.R.T. Robinson + </TD> + </TR> + <TR VALIGN="TOP"> + <TD ALIGN="LEFT"> + + </TD> + <TD ALIGN="RIGHT"> + E*TRADE UK Ltd. + </TD> + </TR> + <TR VALIGN="TOP"> + <TD ALIGN="LEFT"> + + </TD> + <TD ALIGN="RIGHT"> + 25 June 1999 + </TD> + </TR> + </TABLE> + </DIV> + + <H1 ALIGN="CENTER"> + The WWW Common Gateway Interface + <BR> + Version 1.1 + </H1> + +<!--#include virtual="I-D-statement" --> + + <H2> + <A NAME="Abstract"> + Abstract + </A> + </H2> + <P> + The Common Gateway Interface (CGI) is a simple interface for running + external programs, software or gateways under an information server + in a platform-independent manner. Currently, the supported information + servers are HTTP servers. + </P> + <P> + The interface has been in use by the World-Wide Web since 1993. This + specification defines the + "current practice" parameters of the + 'CGI/1.1' interface developed and documented at the U.S. National + Centre for Supercomputing Applications [NCSA-CGI]. + This document also defines the use of the CGI/1.1 interface + on the Unix and AmigaDOS(tm) systems. + </P> + <P> + Discussion of this draft occurs on the CGI-WG mailing list; see the + project Web page at + <SAMP><URL:<A HREF="http://CGI-Spec.Golux.Com/" + >http://CGI-Spec.Golux.Com/</A>></SAMP> + for details on the mailing list and the status of the project. + </P> + +<!--#if expr="$GUI" --> + <H2> + Revision History + </H2> + <P> + The revision history of this draft is being maintained using Web-based + GUI notation, such as struck-through characters and colour-coded + sections. The following legend describes how to determine the origin + of a particular revision according to the colour of the text: + </P> + <DL COMPACT> + <DT>Black + </DT> + <DD>Revision 00, released 28 May 1998 + </DD> + <DT>Green + </DT> + <DD>Revision 01, released 28 December 1998 + <BR> + Major structure change: Section 4, "Request Metadata (Meta-Variables)" + was moved entirely under <A HREF="#7.0">Section 7</A>, "Data Input to the + CGI Script." + Due to the size of this change, it is noted here and the text in its + former location does <EM>not</EM> appear as struckthrough. This has + caused major <A HREF="#6.0">sections 5</A> and following to decrement + by one. Other + large text movements are likewise not marked up. References to RFC + 1738 were changed to 2396 (1738's replacement). + </DD> + <DT>Red + </DT> + <DD>Revision 02, released 2 April, 1999 + <BR> + Added text to <A HREF="#8.3">section 8.3</A> defining correct handling + of HTTP/1.1 + requests using "chunked" Transfer-Encoding. Labelled metavariable + names in <A HREF="#8.0">section 8</A> with the appropriate detail section + numbers. + Clarified allowed usage of <SAMP>Status</SAMP> and + <SAMP>Location</SAMP> response header fields. Included new + Internet-Draft language. + </DD> + <DT>Fuchsia + </DT> + <DD>Revision 03, released 25 June 1999 + <BR> + Changed references from "HTTP" to "Protocol-Specific" for the listing of + things like HTTP_ACCEPT. Changed 'entity-body' and 'content-body' to + 'message-body.' Added a note that response headers must comply with + requirements of the protocol level in use. Added a lot of stuff about + security (section 11). Clarified a bunch of productions. Pointed out + that zero-length and omitted values are indistinguishable in this + specification. Clarified production describing order of fields in + script response header. Clarified issues surrounding encoding of + data. Acknowledged additional contributors, and changed one of + the authors' addresses. + </DD> + </DL> +<!--#endif --> + + <H2> + <A NAME="Contents"> + Table of Contents + </A> + </H2> + <DIV ALIGN="CENTER"> + <PRE> + 1 Introduction..............................................<A + HREF="#1.0" + >TBD</A> + 1.1 Purpose................................................<A + HREF="#1.1" + >TBD</A> + 1.2 Requirements...........................................<A + HREF="#1.2" + >TBD</A> + 1.3 Specifications.........................................<A + HREF="#1.3" + >TBD</A> + 1.4 Terminology............................................<A + HREF="#1.4" + >TBD</A> + 2 Notational Conventions and Generic Grammar................<A + HREF="#2.0" + >TBD</A> + 2.1 Augmented BNF..........................................<A + HREF="#2.1" + >TBD</A> + 2.2 Basic Rules............................................<A + HREF="#2.2" + >TBD</A> + 3 Protocol Parameters.......................................<A + HREF="#3.0" + >TBD</A> + 3.1 URL Encoding...........................................<A + HREF="#3.1" + >TBD</A> + 3.2 The Script-URI.........................................<A + HREF="#3.2" + >TBD</A> + 4 Invoking the Script.......................................<A + HREF="#4.0" + >TBD</A> + 5 The CGI Script Command Line...............................<A + HREF="#5.0" + >TBD</A> + 6 Data Input to the CGI Script..............................<A + HREF="#6.0" + >TBD</A> + 6.1 Request Metadata (Metavariables).......................<A + HREF="#6.1" + >TBD</A> + 6.1.1 AUTH_TYPE...........................................<A + HREF="#6.1.1" + >TBD</A> + 6.1.2 CONTENT_LENGTH......................................<A + HREF="#6.1.2" + >TBD</A> + 6.1.3 CONTENT_TYPE........................................<A + HREF="#6.1.3" + >TBD</A> + 6.1.4 GATEWAY_INTERFACE...................................<A + HREF="#6.1.4" + >TBD</A> + 6.1.5 Protocol-Specific Metavariables.....................<A + HREF="#6.1.5" + >TBD</A> + 6.1.6 PATH_INFO...........................................<A + HREF="#6.1.6" + >TBD</A> + 6.1.7 PATH_TRANSLATED.....................................<A + HREF="#6.1.7" + >TBD</A> + 6.1.8 QUERY_STRING........................................<A + HREF="#6.1.8" + >TBD</A> + 6.1.9 REMOTE_ADDR.........................................<A + HREF="#6.1.9" + >TBD</A> + 6.1.10 REMOTE_HOST........................................<A + HREF="#6.1.10" + >TBD</A> + 6.1.11 REMOTE_IDENT.......................................<A + HREF="#6.1.11" + >TBD</A> + 6.1.12 REMOTE_USER........................................<A + HREF="#6.1.12" + >TBD</A> + 6.1.13 REQUEST_METHOD.....................................<A + HREF="#6.1.13" + >TBD</A> + 6.1.14 SCRIPT_NAME........................................<A + HREF="#6.1.14" + >TBD</A> + 6.1.15 SERVER_NAME........................................<A + HREF="#6.1.15" + >TBD</A> + 6.1.16 SERVER_PORT........................................<A + HREF="#6.1.16" + >TBD</A> + 6.1.17 SERVER_PROTOCOL....................................<A + HREF="#6.1.17" + >TBD</A> + 6.1.18 SERVER_SOFTWARE....................................<A + HREF="#6.1.18" + >TBD</A> + 6.2 Request Message-Bodies................................<A + HREF="#6.2" + >TBD</A> + 7 Data Output from the CGI Script...........................<A + HREF="#7.0" + >TBD</A> + 7.1 Non-Parsed Header Output...............................<A + HREF="#7.1" + >TBD</A> + 7.2 Parsed Header Output...................................<A + HREF="#7.2" + >TBD</A> + 7.2.1 CGI header fields...................................<A + HREF="#7.2.1" + >TBD</A> + 7.2.1.1 Content-Type.....................................<A + HREF="#7.2.1.1" + >TBD</A> + 7.2.1.2 Location.........................................<A + HREF="#7.2.1.2" + >TBD</A> + 7.2.1.3 Status...........................................<A + HREF="#7.2.1.3" + >TBD</A> + 7.2.1.4 Extension header fields..........................<A + HREF="#7.2.1.3" + >TBD</A> + 7.2.2 HTTP header fields..................................<A + HREF="#7.2.2" + >TBD</A> + 8 Server Implementation.....................................<A + HREF="#8.0" + >TBD</A> + 8.1 Requirements for Servers...............................<A + HREF="#8.1" + >TBD</A> + 8.1.1 Script-URI..........................................<A + HREF="#8.1" + >TBD</A> + 8.1.2 Request Message-body Handling.......................<A + HREF="#8.1.2" + >TBD</A> + 8.1.3 Required Metavariables..............................<A + HREF="#8.1.3" + >TBD</A> + 8.1.4 Response Compliance.................................<A + HREF="#8.1.4" + >TBD</A> + 8.2 Recommendations for Servers............................<A + HREF="#8.2" + >TBD</A> + 8.3 Summary of Metavariables...............................<A + HREF="#8.3" + >TBD</A> + 9 Script Implementation.....................................<A + HREF="#9.0" + >TBD</A> + 9.1 Requirements for Scripts...............................<A + HREF="#9.1" + >TBD</A> + 9.2 Recommendations for Scripts............................<A + HREF="#9.2" + >TBD</A> + 10 System Specifications....................................<A + HREF="#10.0" + >TBD</A> + 10.1 AmigaDOS..............................................<A + HREF="#10.1" + >TBD</A> + 10.2 Unix..................................................<A + HREF="#10.2" + >TBD</A> + 11 Security Considerations..................................<A + HREF="#11.0" + >TBD</A> + 11.1 Safe Methods..........................................<A + HREF="#11.1" + >TBD</A> + 11.2 HTTP Header Fields Containing Sensitive Information...<A + HREF="#11.2" + >TBD</A> + 11.3 Script Interference with the Server...................<A + HREF="#11.3" + >TBD</A> + 11.4 Data Length and Buffering Considerations..............<A + HREF="#11.4" + >TBD</A> + 11.5 Stateless Processing..................................<A + HREF="#11.5" + >TBD</A> + 12 Acknowledgments..........................................<A + HREF="#12.0" + >TBD</A> + 13 References...............................................<A + HREF="#13.0" + >TBD</A> + 14 Authors' Addresses.......................................<A + HREF="#14.0" + >TBD</A> + </PRE> + </DIV> + + <H2> + <A NAME="1.0"> + 1. Introduction + </A> + </H2> + + <H3> + <A NAME="1.1"> + 1.1. Purpose + </A> + </H3> + <P> + Together the HTTP [<A HREF="#[3]">3</A>,<A HREF="#[8]">8</A>] server + and the CGI script are responsible + for servicing a client + request by sending back responses. The client + request comprises a Universal Resource Identifier (URI) + [<A HREF="#[1]">1</A>], a + request method, and various ancillary + information about the request + provided by the transport mechanism. + </P> + <P> + The CGI defines the abstract parameters, known as + metavariables, + which describe the client's + request. Together with a + concrete programmer interface this specifies a platform-independent + interface between the script and the HTTP server. + </P> + + <H3> + <A NAME="1.2"> + 1.2. Requirements + </A> + </H3> + <P> + This specification uses the same words as RFC 1123 + [<A HREF="#[5]">5</A>] to define the + significance of each particular requirement. These are: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <DL> + <DT><EM>MUST</EM> + </DT> + <DD> + <P> + This word or the adjective 'required' means that the item is an + absolute requirement of the specification. + </P> + </DD> + <DT><EM>SHOULD</EM> + </DT> + <DD> + <P> + This word or the adjective 'recommended' means that there may + exist valid reasons in particular circumstances to ignore this + item, but the full implications should be understood and the case + carefully weighed before choosing a different course. + </P> + </DD> + <DT><EM>MAY</EM> + </DT> + <DD> + <P> + This word or the adjective 'optional' means that this item is + truly optional. One vendor may choose to include the item because + a particular marketplace requires it or because it enhances the + product, for example; another vendor may omit the same item. + </P> + </DD> + </DL> + <P> + An implementation is not compliant if it fails to satisfy one or more + of the 'must' requirements for the protocols it implements. An + implementation that satisfies all of the 'must' and all of the + 'should' requirements for its features is said to be 'unconditionally + compliant'; one that satisfies all of the 'must' requirements but not + all of the 'should' requirements for its features is said to be + 'conditionally compliant.' + </P> + + <H3> + <A NAME="1.3"> + 1.3. Specifications + </A> + </H3> + <P> + Not all of the functions and features of the CGI are defined in the + main part of this specification. The following phrases are used to + describe the features which are not specified: + </P> + <DL> + <DT><EM>system defined</EM> + </DT> + <DD> + <P> + The feature may differ between systems, but must be the same for + different implementations using the same system. A system will + usually identify a class of operating-systems. Some systems are + defined in + <A HREF="#10.0" + >section 10</A> of this document. + New systems may be defined + by new specifications without revision of this document. + </P> + </DD> + <DT><EM>implementation defined</EM> + </DT> + <DD> + <P> + The behaviour of the feature may vary from implementation to + implementation, but a particular implementation must document its + behaviour. + </P> + </DD> + </DL> + + <H3> + <A NAME="1.4"> + 1.4. Terminology + </A> + </H3> + <P> + This specification uses many terms defined in the HTTP/1.1 + specification [<A HREF="#[8]">8</A>]; however, the following terms are + used here in a + sense which may not accord with their definitions in that document, + or with their common meaning. + </P> + + <DL> + <DT><EM>metavariable</EM> + </DT> + <DD> + <P> + A named parameter that carries information from the server to the + script. It is not necessarily a variable in the operating-system's + environment, although that is the most common implementation. + </P> + </DD> + + <DT><EM>script</EM> + </DT> + <DD> + <P> + The software which is invoked by the server <EM>via</EM> this + interface. It + need not be a standalone program, but could be a + dynamically-loaded or shared library, or even a subroutine in the + server. It <EM>may</EM> be a set of statements + interpreted at run-time, as the term 'script' is frequently + understood, but that is not a requirement and within the context + of this specification the term has the broader definition stated. + </P> + </DD> + <DT><EM>server</EM> + </DT> + <DD> + <P> + The application program which invokes the script in order to service + requests. + </P> + </DD> + </DL> + + <H2> + <A NAME="2.0"> + 2. Notational Conventions and Generic Grammar + </A> + </H2> + + <H3> + <A NAME="2.1"> + 2.1. Augmented BNF + </A> + </H3> + <P> + All of the mechanisms specified in this document are described in + both prose and an augmented Backus-Naur Form (BNF) similar to that + used by RFC 822 [<A HREF="#[6]">6</A>]. This augmented BNF contains + the following constructs: + </P> + <DL> + <DT>name = definition + </DT> + <DD> + <P> + The + definition by the equal character ("="). Whitespace is only + significant in that continuation lines of a definition are + indented. + </P> + </DD> + <DT>"literal" + </DT> + <DD> + <P> + Quotation marks (") surround literal text, except for a literal + quotation mark, which is surrounded by angle-brackets ("<" and ">"). + Unless stated otherwise, the text is case-sensitive. + </P> + </DD> + <DT>rule1 | rule2 + </DT> + <DD> + <P> + Alternative rules are separated by a vertical bar ("|"). + </P> + </DD> + <DT>(rule1 rule2 rule3) + </DT> + <DD> + <P> + Elements enclosed in parentheses are treated as a single element. + </P> + </DD> + <DT>*rule + </DT> + <DD> + <P> + A rule preceded by an asterisk ("*") may have zero or more + occurrences. A rule preceded by an integer followed by an asterisk + must occur at least the specified number of times. + </P> + </DD> + <DT>[rule] + </DT> + <DD> + <P> + An element enclosed in square + brackets ("[" and "]") is optional. + </P> + </DD> + </DL> + + <H3> + <A NAME="2.2"> + 2.2. Basic Rules + </A> + </H3> + <P> + The following rules are used throughout this specification to + describe basic parsing constructs. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + alpha = lowalpha | hialpha + alphanum = alpha | digit + lowalpha = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" + | "i" | "j" | "k" | "l" | "m" | "n" | "o" | "p" + | "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" + | "y" | "z" + hialpha = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" + | "I" | "J" | "K" | "L" | "M" | "N" | "O" | "P" + | "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" + | "Y" | "Z" + digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" + | "8" | "9" + hex = digit | "A" | "B" | "C" | "D" | "E" | "F" | "a" + | "b" | "c" | "d" | "e" | "f" + escaped = "%" hex hex + OCTET = <any 8-bit sequence of data> + CHAR = <any US-ASCII character (octets 0 - 127)> + CTL = <any US-ASCII control character + (octets 0 - 31) and DEL (127)> + CR = <US-ASCII CR, carriage return (13)> + LF = <US-ASCII LF, linefeed (10)> + SP = <US-ASCII SP, space (32)> + HT = <US-ASCII HT, horizontal tab (9)> + NL = CR | LF + LWSP = SP | HT | NL + tspecial = "(" | ")" | "@" | "," | ";" | ":" | "\" | <"> + | "/" | "[" | "]" | "?" | "<" | ">" | "{" | "}" + | SP | HT | NL + token = 1*<any CHAR except CTLs or tspecials> + quoted-string = ( <"> *qdtext <"> ) | ( "<" *qatext ">") + qdtext = <any CHAR except <"> and CTLs but including LWSP> + qatext = <any CHAR except "<", ">" and CTLs but + including LWSP> + mark = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")" + unreserved = alphanum | mark + reserved = ";" | "/" | "?" | ":" | "@" | "&" | "=" | + "$" | "," + uric = reserved | unreserved | escaped + </PRE> + <P> + Note that newline (NL) need not be a single character, but can be a + character sequence. + </P> + + <H2> + <A NAME="3.0"> + 3. Protocol Parameters + </A> + </H2> + + <H3> + <A NAME="3.1"> + 3.1. URL Encoding + </A> + </H3> + <P> + Some variables and constructs used here are described as being + 'URL-encoded'. This encoding is described in section + 2 of RFC + 2396 + [<A HREF="#[4]">4</A>]. + </P> + <P> + An alternate "shortcut" encoding for representing the space + character exists and is in common use. Scripts MUST be prepared to + recognise both '+' and '%20' as an encoded space in a + URL-encoded value. + </P> + <P> + Note that some unsafe characters may have different semantics if + they are encoded. The definition of which characters are unsafe + depends on the context. + For example, the following two URLs do not + necessarily refer to the same resource: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + http://somehost.com/somedir%2Fvalue + http://somehost.com/somedir/value + </PRE> + <P> + See section + 2 of RFC + 2396 [<A HREF="#[4]">4</A>] + for authoritative treatment of this issue. + </P> + + <H3> + <A NAME="3.2"> + 3.2. The Script-URI + </A> + </H3> + <P> + The 'Script-URI' is defined as the URI of the resource identified + by the metavariables. Often, + this URI will be the same as + the URI requested by the client (the 'Client-URI'); however, it need + not be. Instead, it could be a URI invented by the server, and so it + can only be used in the context of the server and its CGI interface. + </P> + <P> + The Script-URI has the syntax of generic-RL as defined in section 2.1 + of RFC 1808 [<A HREF="#[7]">7</A>], with the exception that object + parameters and + fragment identifiers are not permitted: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + <scheme>://<host><port>/<path>?<query> + </PRE> + <P> + The various components of the + Script-URI + are defined by some of the + metavariables (see + <A HREF="#4.0">section 4</A> + below); + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + script-uri = protocol "://" SERVER_NAME ":" SERVER_PORT enc-script + enc-path-info "?" QUERY_STRING + </PRE> + <P> + where 'protocol' is obtained + from SERVER_PROTOCOL, 'enc-script' is a + URL-encoded version of SCRIPT_NAME and 'enc-path-info' is a + URL-encoded version of PATH_INFO. See + <A HREF="#4.6">section 4.6</A> for more information about the PATH_INFO + metavariable. + </P> + <P> + Note that the scheme and the protocol are <EM>not</EM> identical; + for instance, a resource accessed <EM>via</EM> an SSL mechanism + may have a Client-URI with a scheme of "<SAMP>https</SAMP>" + rather than "<SAMP>http</SAMP>". CGI/1.1 provides no means + for the script to reconstruct this, and therefore + the Script-URI includes the base protocol used. + </P> + + <H2> + <A NAME="4.0"> + 4. Invoking the Script + </A> + </H2> + <P> + The + script is invoked in a system defined manner. Unless specified + otherwise, the file containing the script will be invoked as an + executable program. + </P> + + <H2> + <A NAME="5.0"> + 5. The CGI Script Command Line + </A> + </H2> + <P> + Some systems support a method for supplying an array of strings to + the CGI script. This is only used in the case of an 'indexed' query. + This is identified by a "GET" or "HEAD" HTTP request with a URL + query + string not containing any unencoded "=" characters. For such a + request, + servers SHOULD parse the search string + into words, using the following rules: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + search-string = search-word *( "+" search-word ) + search-word = 1*schar + schar = xunreserved | escaped | xreserved + xunreserved = alpha | digit | xsafe | extra + xsafe = "$" | "-" | "_" | "." + xreserved = ";" | "/" | "?" | ":" | "@" | "&" + </PRE> + <P> + After parsing, each word is URL-decoded, optionally encoded in a + system defined manner, + and then the argument list is set to the list + of words. + </P> + <P> + If the server cannot create any part of the argument list, then the + server SHOULD NOT generate any command line information. For example, the + number of arguments may be greater than operating system or server + limitations permit, or one of the words may not be representable as an + argument. + </P> + <P> + Scripts SHOULD check to see if the QUERY_STRING value contains an + unencoded "=" character, and SHOULD NOT use the command line arguments + if it does. + </P> + + <H2> + <A NAME="6.0"> + 6. Data Input to the CGI Script + </A> + </H2> + <P> + Information about a request comes from two different sources: the + request header, and any associated + message-body. + Servers MUST + make portions of this information available to + scripts. + </P> + + <H3> + <A NAME="6.1"> + 6.1. Request Metadata + (Metavariables) + </A> + </H3> + <P> + Each CGI server + implementation MUST define a mechanism + to pass data about the request from + the server to the script. + The metavariables containing these + data + are accessed by the script in a system + defined manner. + The + representation of the characters in the + metavariables is + system defined. + </P> + <P> + This specification does not distinguish between the representation of + null values and missing ones. Whether null or missing values + (such as a query component of "?" or "", respectively) are represented + by undefined metavariables or by metavariables with values of "" is + implementation-defined. + </P> + <P> + Case is not significant in the + metavariable + names, in that there cannot be two + different variables + whose names differ in case only. Here they are + shown using a canonical representation of capitals plus underscore + ("_"). The actual representation of the names is system defined; for + a particular system the representation MAY be defined differently + than this. + </P> + <P> + Metavariable + values MUST be + considered case-sensitive except as noted + otherwise. + </P> + <P> + The canonical + metavariables + defined by this specification are: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + AUTH_TYPE + CONTENT_LENGTH + CONTENT_TYPE + GATEWAY_INTERFACE + PATH_INFO + PATH_TRANSLATED + QUERY_STRING + REMOTE_ADDR + REMOTE_HOST + REMOTE_IDENT + REMOTE_USER + REQUEST_METHOD + SCRIPT_NAME + SERVER_NAME + SERVER_PORT + SERVER_PROTOCOL + SERVER_SOFTWARE + </PRE> + <P> + Metavariables with names beginning with the protocol name (<EM>e.g.</EM>, + "HTTP_ACCEPT") are also canonical in their description of request header + fields. The number and meaning of these fields may change independently + of this specification. (See also <A HREF="#6.1.5">section 6.1.5</A>.) + </P> + + <H4> + <A NAME="6.1.1"> + 6.1.1. AUTH_TYPE + </A> + </H4> + <P> + This variable is specific to requests made + <EM>via</EM> the + "<CODE>http</CODE>" + scheme. + </P> + <P> + If the Script-URI + required access authentication for external + access, then the server + MUST set + the value of + this variable + from the '<SAMP>auth-scheme</SAMP>' token in + the request's "<SAMP>Authorization</SAMP>" header + field. + Otherwise + it is + set to NULL. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + AUTH_TYPE = "" | auth-scheme + auth-scheme = "Basic" | "Digest" | token + </PRE> + <P> + HTTP access authentication schemes are described in section 11 of the + HTTP/1.1 specification [<A HREF="#[8]">8</A>]. The auth-scheme is + not case-sensitive. + </P> + <P> + Servers + MUST + provide this metavariable + to scripts if the request + header included an "<SAMP>Authorization</SAMP>" field + that was authenticated. + </P> + + <H4> + <A NAME="6.1.2"> + 6.1.2. CONTENT_LENGTH + </A> + </H4> + <P> + This + metavariable + is set to the + size of the message-body + entity attached to the request, if any, in decimal + number of octets. If no data are attached, then this + metavariable + is either NULL or not + defined. The syntax is + the same as for + the HTTP "<SAMP>Content-Length</SAMP>" header field (section 14.14, HTTP/1.1 + specification [<A HREF="#[8]">8</A>]). + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + CONTENT_LENGTH = "" | 1*digit + </PRE> + <P> + Servers MUST provide this metavariable + to scripts if the request + was accompanied by a + message-body entity. + </P> + + <H4> + <A NAME="6.1.3"> + 6.1.3. CONTENT_TYPE + </A> + </H4> + <P> + If the request includes a + message-body, + CONTENT_TYPE is set + to + the Internet Media Type + [<A HREF="#[9]">9</A>] of the attached + entity if the type was provided <EM>via</EM> + a "<SAMP>Content-type</SAMP>" field in the + request header, or if the server can determine it in the absence + of a supplied "<SAMP>Content-type</SAMP>" field. The syntax is the + same as for the HTTP + "<SAMP>Content-Type</SAMP>" header field. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + CONTENT_TYPE = "" | media-type + media-type = type "/" subtype *( ";" parameter) + type = token + subtype = token + parameter = attribute "=" value + attribute = token + value = token | quoted-string + </PRE> + <P> + The type, subtype, + and parameter attribute names are not + case-sensitive. Parameter values MAY be case sensitive. + Media types and their use in HTTP are described + in section 3.7 of the + HTTP/1.1 specification [<A HREF="#[8]">8</A>]. + </P> + <P> + Example: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + application/x-www-form-urlencoded + </PRE> + <P> + There is no default value for this variable. If and only if it is + unset, then the script MAY attempt to determine the media type from + the data received. If the type remains unknown, then + the script MAY choose to either assume a + content-type of + <SAMP>application/octet-stream</SAMP> + or reject the request with a 415 ("Unsupported Media Type") + error. See <A HREF="#7.2.1.3">section 7.2.1.3</A> + for more information about returning error status values. + </P> + <P> + Servers MUST provide this metavariable + to scripts if + a "<SAMP>Content-Type</SAMP>" field was present + in the original request header. If the server receives a request + with an attached entity but no "<SAMP>Content-Type</SAMP>" + header field, it MAY attempt to + determine the correct datatype, or it MAY omit this + metavariable when + communicating the request information to the script. + </P> + + <H4> + <A NAME="6.1.4"> + 6.1.4. GATEWAY_INTERFACE + </A> + </H4> + <P> + This + metavariable + is set to + the dialect of CGI being used + by the server to communicate with the script. + Syntax: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + GATEWAY_INTERFACE = "CGI" "/" major "." minor + major = 1*digit + minor = 1*digit + </PRE> + <P> + Note that the major and minor numbers are treated as separate + integers and hence each may be + more than a single + digit. Thus CGI/2.4 is a lower version than CGI/2.13 which in turn + is lower than CGI/12.3. Leading zeros in either + the major or the minor number MUST be ignored by scripts and + SHOULD NOT be generated by servers. + </P> + <P> + This document defines the 1.1 version of the CGI interface + ("CGI/1.1"). + </P> + <P> + Servers MUST provide this metavariable + to scripts. + </P> + + <H4> + <A NAME="6.1.5"> + 6.1.5. Protocol-Specific Metavariables + </A> + </H4> + <P> + These metavariables are specific to + the protocol + <EM>via</EM> which the request is made. + Interpretation of these variables depends on the value of + the + SERVER_PROTOCOL + metavariable + (see + <A HREF="#6.1.17">section 6.1.17</A>). + </P> + <P> + Metavariables + with names beginning with "HTTP_" contain + values from the request header, if the + scheme used was HTTP. + Each + HTTP header field name is converted to upper case, has all occurrences of + "-" replaced with "_", + and has "HTTP_" prepended to form + the metavariable name. + Similar transformations are applied for other + protocols. + The header data MAY be presented as sent + by the client, or MAY be rewritten in ways which do not change its + semantics. If multiple header fields with the same field-name are received + then the server + MUST rewrite them as though they + had been received as a single header field having the same + semantics before being represented in a + metavariable. + Similarly, a header field that is received on more than one line + MUST be merged into a single line. The server MUST, if necessary, + change the representation of the data (for example, the character + set) to be appropriate for a CGI + metavariable. + <!-- ###NOTE: See if 2068 describes this thoroughly, and + point there if so. --> + </P> + <P> + Servers are + not required to create + metavariables for all + the request + header fields that they + receive. In particular, + they MAY + decline to make available any + header fields carrying authentication information, such as + "<SAMP>Authorization</SAMP>", or + which are available to the script + <EM>via</EM> other metavariables, + such as "<SAMP>Content-Length</SAMP>" and "<SAMP>Content-Type</SAMP>". + </P> + + <H4> + <A NAME="6.1.6"> + 6.1.6. PATH_INFO + </A> + </H4> + <P> + The PATH_INFO + metavariable + specifies + a path to be interpreted by the CGI script. It identifies the + resource or sub-resource to be returned + by the CGI + script, and it is derived from the portion + of the URI path following the script name but preceding + any query data. + The syntax + and semantics are similar to a decoded HTTP URL + 'path' token + (defined in + RFC 2396 + [<A HREF="#[4]">4</A>]), with the exception + that a PATH_INFO of "/" + represents a single void path segment. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + PATH_INFO = "" | ( "/" path ) + path = segment *( "/" segment ) + segment = *pchar + pchar = <any CHAR except "/"> + </PRE> + <P> + The PATH_INFO string is the trailing part of the <path> component of + the Script-URI + (see <A HREF="#3.2">section 3.2</A>) + that follows the SCRIPT_NAME + portion of the path. + </P> + <P> + Servers MAY impose their own restrictions and + limitations on what values they will accept for PATH_INFO, and MAY + reject or edit any values they + consider objectionable before passing + them to the script. + </P> + <P> + Servers MUST make this URI component available + to CGI scripts. The PATH_INFO + value is case-sensitive, and the + server MUST preserve the case of the PATH_INFO element of the URI + when making it available to scripts. + </P> + + <H4> + <A NAME="6.1.7"> + 6.1.7. PATH_TRANSLATED + </A> + </H4> + <P> + PATH_TRANSLATED is derived by taking any path-info component of the + request URI (see + <A HREF="#6.1.6">section 6.1.6</A>), decoding it + (see <A HREF="#3.1">section 3.1</A>), parsing it as a URI in its own + right, and performing any virtual-to-physical + translation appropriate to map it onto the + server's document repository structure. + If the request URI includes no path-info + component, the PATH_TRANSLATED metavariable SHOULD NOT be defined. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + PATH_TRANSLATED = *CHAR + </PRE> + <P> + For a request such as the following: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + http://somehost.com/cgi-bin/somescript/this%2eis%2epath%2einfo + </PRE> + <P> + the PATH_INFO component would be decoded, and the result + parsed as though it were a request for the following: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + http://somehost.com/this.is.the.path.info + </PRE> + <P> + This would then be translated to a + location in the server's document repository, + perhaps a filesystem path something + like this: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + /usr/local/www/htdocs/this.is.the.path.info + </PRE> + <P> + The result of the translation is the value of PATH_TRANSLATED. + </P> + <P> + The value of PATH_TRANSLATED may or may not map to a valid + repository + location. + Servers MUST preserve the case of the path-info + segment if and only if the underlying + repository + supports case-sensitive + names. If the + repository + is only case-aware, case-preserving, or case-blind + with regard to + document names, + servers are not required to preserve the + case of the original segment through the translation. + </P> + <P> + The + translation + algorithm the server uses to derive PATH_TRANSLATED is + implementation defined; CGI scripts which use this variable may + suffer limited portability. + </P> + <P> + Servers SHOULD provide this metavariable + to scripts if and only if the request URI includes a + path-info component. + </P> + + <H4> + <A NAME="6.1.8"> + 6.1.8. QUERY_STRING + </A> + </H4> + <P> + A URL-encoded + string; the <query> part of the + Script-URI. + (See + <A HREF="#3.2">section 3.2</A>.) + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + QUERY_STRING = query-string + query-string = *uric + </PRE> + <P> + The URL syntax for a query + string is described in + section 3 of + RFC 2396 + [<A HREF="#[4]">4</A>]. + </P> + <P> + Servers MUST supply this value to scripts. + The QUERY_STRING value is case-sensitive. + If the Script-URI does not include a query component, + the QUERY_STRING metavariable MUST be defined as an empty string (""). + </P> + + <H4> + <A NAME="6.1.9"> + 6.1.9. REMOTE_ADDR + </A> + </H4> + <P> + The IP address of the client + sending the request to the server. This + is not necessarily that of the user + agent + (such as if the request came through a proxy). + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + REMOTE_ADDR = hostnumber + hostnumber = ipv4-address | ipv6-address + </PRE> + <P> + The definitions of <SAMP>ipv4-address</SAMP> and <SAMP>ipv6-address</SAMP> + are provided in Appendix B of RFC 2373 [<A HREF="#[13]">13</A>]. + </P> + <P> + Servers MUST supply this value to scripts. + </P> + + <H4> + <A NAME="6.1.10"> + 6.1.10. REMOTE_HOST + </A> + </H4> + <P> + The fully qualified domain name of the + client sending the request to + the server, if available, otherwise NULL. + (See <A HREF="#6.1.9">section 6.1.9</A>.) + Fully qualified domain names take the form as described in + section 3.5 of RFC 1034 [<A HREF="#[10]">10</A>] and section 2.1 of + RFC 1123 [<A HREF="#[5]">5</A>]. Domain names are not case sensitive. + </P> + <P> + Servers SHOULD provide this information to + scripts. + </P> + + <H4> + <A NAME="6.1.11"> + 6.1.11. REMOTE_IDENT + </A> + </H4> + <P> + The identity information reported about the connection by a + RFC 1413 [<A HREF="#[11]">11</A>] request to the remote agent, if + available. Servers + MAY choose not + to support this feature, or not to request the data + for efficiency reasons. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + REMOTE_IDENT = *CHAR + </PRE> + <P> + The data returned + may be used for authentication purposes, but the level + of trust reposed in them should be minimal. + </P> + <P> + Servers MAY supply this information to scripts if the + RFC1413 [<A HREF="#[11]">11</A>] lookup is performed. + </P> + + <H4> + <A NAME="6.1.12"> + 6.1.12. REMOTE_USER + </A> + </H4> + <P> + If the request required authentication using the "Basic" + mechanism (<EM>i.e.</EM>, the AUTH_TYPE + metavariable is set + to "Basic"), then the value of the REMOTE_USER + metavariable is set to the + user-ID supplied. In all other cases + the value of this metavariable + is undefined. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + REMOTE_USER = *OCTET + </PRE> + <P> + This variable is specific to requests made <EM>via</EM> the + HTTP protocol. + </P> + <P> + Servers SHOULD provide this metavariable + to scripts. + </P> + + <H4> + <A NAME="6.1.13"> + 6.1.13. REQUEST_METHOD + </A> + </H4> + <P> + The REQUEST_METHOD + metavariable + is set to the + method with which the request was made, as described in section + 5.1.1 of the HTTP/1.0 specification [<A HREF="#[3]">3</A>] and + section 5.1.1 of the + HTTP/1.1 specification [<A HREF="#[8]">8</A>]. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + REQUEST_METHOD = http-method + http-method = "GET" | "HEAD" | "POST" | "PUT" | "DELETE" + | "OPTIONS" | "TRACE" | extension-method + extension-method = token + </PRE> + <P> + The method is case sensitive. + CGI/1.1 servers MAY choose to process some methods + directly rather than passing them to scripts. + </P> + <P> + This variable is specific to requests made with HTTP. + </P> + <P> + Servers MUST provide this metavariable + to scripts. + </P> + + <H4> + <A NAME="6.1.14"> + 6.1.14. SCRIPT_NAME + </A> + </H4> + <P> + The SCRIPT_NAME + metavariable + is + set to a URL path that could identify the CGI script (rather than the + script's + output). The syntax and semantics are identical to a + decoded HTTP URL 'path' token + (see RFC 2396 + [<A HREF="#[4]">4</A>]). + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + SCRIPT_NAME = "" | ( "/" [ path ] ) + </PRE> + <P> + The SCRIPT_NAME string is some leading part of the <path> component + of the Script-URI derived in some + implementation defined manner. + No PATH_INFO or QUERY_STRING segments + (see sections <A HREF="#6.1.6">6.1.6</A> and + <A HREF="#6.1.8">6.1.8</A>) are included + in the SCRIPT_NAME value. + </P> + <P> + Servers MUST provide this metavariable + to scripts. + </P> + + <H4> + <A NAME="6.1.15"> + 6.1.15. SERVER_NAME + </A> + </H4> + <P> + The SERVER_NAME + metavariable + is set to the + name of the + server, as + derived from the <host> part of the + Script-URI + (see <A HREF="#3.2">section 3.2</A>). + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + SERVER_NAME = hostname | hostnumber + </PRE> + <P> + Servers MUST provide this metavariable + to scripts. + </P> + + <H4> + <A NAME="6.1.16"> + 6.1.16. SERVER_PORT + </A> + </H4> + <P> + The SERVER_PORT + metavariable + is set to the + port on which the + request was received, as used in the <port> + part of the Script-URI. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + SERVER_PORT = 1*digit + </PRE> + <P> + If the <port> portion of the script-URI is blank, the actual + port number upon which the request was received MUST be supplied. + </P> + <P> + Servers MUST provide this metavariable + to scripts. + </P> + + <H4> + <A NAME="6.1.17"> + 6.1.17. SERVER_PROTOCOL + </A> + </H4> + <P> + The SERVER_PROTOCOL + metavariable + is set to + the + name and revision of the information protocol with which + the + request + arrived. This is not necessarily the same as the protocol version used by + the server in its response to the client. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + SERVER_PROTOCOL = HTTP-Version | extension-version + | extension-token + HTTP-Version = "HTTP" "/" 1*digit "." 1*digit + extension-version = protocol "/" 1*digit "." 1*digit + protocol = 1*( alpha | digit | "+" | "-" | "." ) + extension-token = token + </PRE> + <P> + 'protocol' is a version of the <scheme> part of the + Script-URI, but is + not identical to it. For example, the scheme of a request may be + "<SAMP>https</SAMP>" while the protocol remains "<SAMP>http</SAMP>". + The protocol is not case sensitive, but + by convention, 'protocol' is in + upper case. + </P> + <P> + A well-known extension token value is "INCLUDED", + which signals that the current document is being included as part of + a composite document, rather than being the direct target of the + client request. + </P> + <P> + Servers MUST provide this metavariable + to scripts. + </P> + + <H4> + <A NAME="6.1.18"> + 6.1.18. SERVER_SOFTWARE + </A> + </H4> + <P> + The SERVER_SOFTWARE + metavariable + is set to the + name and version of the information server software answering the + request (and running the gateway). + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + SERVER_SOFTWARE = 1*product + product = token [ "/" product-version ] + product-version = token + </PRE> + <P> + Servers MUST provide this metavariable + to scripts. + </P> + + <H3> + <A NAME="6.2"> + 6.2. Request Message-Bodies + </A> + </H3> + <P> + As there may be a data entity attached to the request, there MUST be + a system defined method for the script to read + these data. Unless + defined otherwise, this will be <EM>via</EM> the 'standard input' file + descriptor. + </P> + <P> + If the CONTENT_LENGTH value (see <A HREF="#6.1.2">section 6.1.2</A>) + is non-NULL, the server MUST supply at least that many bytes to + scripts on the standard input stream. + Scripts are + not obliged to read the data. + Servers MAY signal an EOF condition after CONTENT_LENGTH bytes have been + read, but are + not obligated to do so. Therefore, scripts + MUST NOT + attempt to read more than CONTENT_LENGTH bytes, even if more data + are available. + </P> + <P> + For non-parsed header (NPH) scripts (see + <A HREF="#7.1">section 7.1</A> + below), + servers SHOULD + attempt to ensure that the data + supplied to the script are precisely + as supplied by the client and unaltered by + the server. + </P> + <P> + <A HREF="#8.1.2">Section 8.1.2</A> describes the requirements of + servers with regard to requests that include + message-bodies. + </P> + + <H2> + <A NAME="7.0"> + 7. Data Output from the CGI Script + </A> + </H2> + <P> + There MUST be a system defined method for the script to send data + back to the server or client; a script MUST always return some data. + Unless defined otherwise, this will be <EM>via</EM> the 'standard + output' file descriptor. + </P> + <P> + There are two forms of output that scripts can supply to servers: non-parsed + header (NPH) output, and parsed header output. + Servers MUST support parsed header + output and MAY support NPH output. The method of + distinguishing between the two + types of output (or scripts) is implementation defined. + </P> + <P> + Servers MAY implement a timeout period within which data must be + received from scripts. If a server implementation defines such + a timeout and receives no data from a script within the timeout + period, the server MAY terminate the script process and SHOULD + abort the client request with + either a + '504 Gateway Timed Out' or a + '500 Internal Server Error' response. + </P> + + <H3> + <A NAME="7.1"> + 7.1. Non-Parsed Header Output + </A> + </H3> + <P> + Scripts using the NPH output form + MUST return a complete HTTP response message, as described + in Section 6 of the HTTP specifications + [<A HREF="#[3]">3</A>,<A HREF="#[8]">8</A>]. + NPH scripts + MUST use the SERVER_PROTOCOL variable to determine the appropriate format + for a response. + </P> + <P> + Servers + SHOULD attempt to ensure that the script output is sent + directly to the client, with minimal + internal and no transport-visible + buffering. + </P> + + <H3> + <A NAME="7.2"> + 7.2. Parsed Header Output + </A> + </H3> + <P> + Scripts using the parsed header output form MUST supply + a CGI response message to the server + as follows: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + CGI-Response = *optional-field CGI-Field *optional-field NL [ Message-Body ] + optional-field = ( CGI-Field | HTTP-Field ) + CGI-Field = Content-type + | Location + | Status + | extension-header + </PRE> + <P><!-- ##### If HTTP defines x-headers, remove ours except x-cgi- --> + The response comprises a header and a body, separated by a blank line. + The body may be NULL. + The header fields are either CGI header fields to be interpreted by + the server, or HTTP header fields + to be included in the response returned + to the client + if the request method is HTTP. At least one + CGI-Field MUST be + supplied, but no CGI field name may be used more than once + in a response. + If a body is supplied, then a "<SAMP>Content-type</SAMP>" + header field MUST be + supplied by the script, + otherwise the script MUST send a "<SAMP>Location</SAMP>" + or "<SAMP>Status</SAMP>" header field. If a + <SAMP>Location</SAMP> CGI-Field + is returned, then the script MUST NOT supply + any HTTP-Fields. + </P> + <P> + Each header field in a CGI-Response MUST be specified on a single line; + CGI/1.1 does not support continuation lines. + </P> + + <H4> + <A NAME="7.2.1"> + 7.2.1. CGI header fields + </A> + </H4> + <P> + The CGI header fields have the generic syntax: + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + generic-field = field-name ":" [ field-value ] NL + field-name = token + field-value = *( field-content | LWSP ) + field-content = *( token | tspecial | quoted-string ) + </PRE> + <P> + The field-name is not case sensitive; a NULL field value is + equivalent to the header field not being sent. + </P> + + <H4> + <A NAME="7.2.1.1"> + 7.2.1.1. Content-Type + </A> + </H4> + <P> + The Internet Media Type [<A HREF="#[9]">9</A>] of the entity + body, which is to be sent unmodified to the client. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + Content-Type = "Content-Type" ":" media-type NL + </PRE> + <P> + This is actually an HTTP-Field + rather than a CGI-Field, but + it is listed here because of its importance in the CGI dialogue as + a member of the "one of these is required" set of header + fields. + </P> + + <H4> + <A NAME="7.2.1.2"> + 7.2.1.2. Location + </A> + </H4> + <P> + This is used to specify to the server that the script is returning a + reference to a document rather than an actual document. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + Location = "Location" ":" + ( fragment-URI | rel-URL-abs-path ) NL + fragment-URI = URI [ # fragmentid ] + URI = scheme ":" *qchar + fragmentid = *qchar + rel-URL-abs-path = "/" [ hpath ] [ "?" query-string ] + hpath = fpsegment *( "/" psegment ) + fpsegment = 1*hchar + psegment = *hchar + hchar = alpha | digit | safe | extra + | ":" | "@" | "& | "=" + </PRE> + <P> + The Location + value is either an absolute URI with optional fragment, + as defined in RFC 1630 [<A HREF="#[1]">1</A>], or an absolute path + within the server's URI space (<EM>i.e.</EM>, + omitting the scheme and network-related fields) and optional + query-string. If an absolute URI is returned by the script, + then the + server MUST generate a + '302 redirect' HTTP response + message unless the script has supplied an + explicit Status response header field. + Scripts returning an absolute URI MAY choose to + provide a message-body. Servers MUST make any appropriate modifications + to the script's output to ensure the response to the user-agent complies + with the response protocol version. + If the Location value is a path, then the server + MUST generate + the response that it would have produced in response to a request + containing the URL + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + scheme "://" SERVER_NAME ":" SERVER_PORT rel-URL-abs-path + </PRE> + <P> + Note: If the request was accompanied by a + message-body + (such as for a POST request), and the script + redirects the request with a Location field, the + message-body + may not be + available to the resource that is the target of the redirect. + </P> + + <H4> + <A NAME="7.2.1.3"> + 7.2.1.3. Status + </A> + </H4> + <P> + The "<SAMP>Status</SAMP>" header field is used to indicate to the server what + status code the server MUST use in the response message. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + Status = "Status" ":" digit digit digit SP reason-phrase NL + reason-phrase = *<CHAR, excluding CTLs, NL> + </PRE> + <P> + The valid status codes are listed in section 6.1.1 of the HTTP/1.0 + specifications [<A HREF="#[3]">3</A>]. If the SERVER_PROTOCOL is + "HTTP/1.1", then the status codes defined in the HTTP/1.1 + specification [<A HREF="#[8]">8</A>] may + be used. If the script does not return a "<SAMP>Status</SAMP>" header + field, then "200 OK" SHOULD be assumed by the server. + </P> + <P> + If a script is being used to handle a particular error or condition + encountered by the server, such as a '404 Not Found' error, the script + SHOULD use the "<SAMP>Status</SAMP>" CGI header field to propagate the error + condition back to the client. <EM>E.g.</EM>, in the example mentioned it + SHOULD include a "Status: 404 Not Found" in the + header data returned to the server. + </P> + + <H4> + <A NAME="7.2.1.4"> + 7.2.1.4. Extension header fields + </A> + </H4> + <P> + Scripts MAY include in their CGI response header additional fields + not defined in this or the HTTP specification. + These are called "extension" fields, + and have the syntax of a <SAMP>generic-field</SAMP> as defined in + <A HREF="#7.2.1">section 7.2.1</A>. The name of an extension field + MUST NOT conflict with a field name defined in this or any other + specification; extension field names SHOULD begin with "X-CGI-" + to ensure uniqueness. + </P> + + <H4> + <A NAME="7.2.2"> + 7.2.2. HTTP header fields + </A> + </H4> + <P> + The script MAY return any other header fields defined by the + specification + for the SERVER_PROTOCOL (HTTP/1.0 [<A HREF="#[3]">3</A>] or HTTP/1.1 + [<A HREF="#[8]">8</A>]). + Servers MUST resolve conflicts beteen CGI header + and HTTP header formats or names (see <A HREF="#8.0">section 8</A>). + </P> + + <H2> + <A NAME="8.0"> + 8. Server Implementation + </A> + </H2> + <P> + This section defines the requirements that must be met by HTTP + servers in order to provide a coherent and correct CGI/1.1 + environment in which scripts may function. It is intended + primarily for server implementors, but it is useful for + script authors to be familiar with the information as well. + </P> + + <H3> + <A NAME="8.1"> + 8.1. Requirements for Servers + </A> + </H3> + <P> + In order to be considered CGI/1.1-compliant, a server must meet + certain basic criteria and provide certain minimal functionality. + The details of these requirements are described in the following sections. + </P> + + <H3> + <A NAME="8.1.1"> + 8.1.1. Script-URI + </A> + </H3> + <P> + Servers MUST support the standard mechanism (described below) which + allows + script authors to determine + what URL to use in documents + which reference the script; + specifically, what URL to use in order to + achieve particular settings of the + metavariables. This + mechanism is as follows: + </P> + <P> + The server + MUST translate the header data from the CGI header field syntax to + the HTTP + header field syntax if these differ. For example, the character + sequence for + newline (such as Unix's ASCII NL) used by CGI scripts may not be the + same as that used by HTTP (ASCII CR followed by LF). The server MUST + also resolve any conflicts between header fields returned by the script + and header fields that it would otherwise send itself. + </P> + + <H3> + <A NAME="8.1.2"> + 8.1.2. Request Message-body Handling + </A> + </H3> + <P> + These are the requirements for server handling of message-bodies directed + to CGI/1.1 resources: + </P> + <OL> + <LI>The message-body the server provides to the CGI script MUST + have any transfer encodings removed. + </LI> + <LI>The server MUST derive and provide a value for the CONTENT_LENGTH + metavariable that reflects the length of the message-body after any + transfer decoding. + </LI> + <LI>The server MUST leave intact any content-encodings of the message-body. + </LI> + </OL> + + <H3> + <A NAME="8.1.3"> + 8.1.3. Required Metavariables + </A> + </H3> + <P> + Servers MUST provide scripts with certain information and + metavariables + as described in <A HREF="#8.3">section 8.3</A>. + </P> + + <H3> + <A NAME="8.1.4"> + 8.1.4. Response Compliance + </A> + </H3> + <P> + Servers MUST ensure that responses sent to the user-agent meet all + requirements of the protocol level in effect. This may involve + modifying, deleting, or augmenting any header + fields and/or message-body supplied by the script. + </P> + + <H3> + <A NAME="8.2"> + 8.2. Recommendations for Servers + </A> + </H3> + <P> + Servers SHOULD provide the "<SAMP>query</SAMP>" component of the script-URI + as command-line arguments to scripts if it does not + contain any unencoded '=' characters and the command-line arguments can + be generated in an unambiguous manner. + (See <A HREF="#5.0">section 5</A>.) + </P> + <P> + Servers SHOULD set the AUTH_TYPE + metavariable to the value of the + '<SAMP>auth-scheme</SAMP>' token of the "<SAMP>Authorization</SAMP>" + field if it was supplied as part of the request header. + (See <A HREF="#6.1.1">section 6.1.1</A>.) + </P> + <P> + Where applicable, servers SHOULD set the current working directory + to the directory in which the script is located before invoking + it. + </P> + <P> + Servers MAY reject with error '404 Not Found' + any requests that would result in + an encoded "/" being decoded into PATH_INFO or SCRIPT_NAME, as this + might represent a loss of information to the script. + </P> + <P> + Although the server and the CGI script need not be consistent in + their handling of URL paths (client URLs and the PATH_INFO data, + respectively), server authors may wish to impose consistency. + So the server implementation SHOULD define its behaviour for the + following cases: + </P> + <OL> + <LI>define any restrictions on allowed characters, in particular + whether ASCII NUL is permitted; + </LI> + <LI>define any restrictions on allowed path segments, in particular + whether non-terminal NULL segments are permitted; + </LI> + <LI>define the behaviour for <SAMP>"."</SAMP> or <SAMP>".."</SAMP> path + segments; <EM>i.e.</EM>, whether they are prohibited, treated as + ordinary path + segments or interpreted in accordance with the relative URL + specification [<A HREF="#[7]">7</A>]; + </LI> + <LI>define any limits of the implementation, including limits on path or + search string lengths, and limits on the volume of header data the server + will parse. + </LI><!-- ##### Move the field resolution/translation para below here --> + </OL> + <P> + Servers MAY generate the + Script-URI in + any way from the client URI, + or from any other data (but the behaviour SHOULD be documented). + </P> + <P> + For non-parsed header (NPH) scripts (see + <A HREF="#7.1">section 7.1</A>), servers SHOULD + attempt to ensure that the script input comes directly from the + client, with minimal buffering. For all scripts the data will be + as supplied by the client. + </P> + + <H3> + <A NAME="8.3"> + 8.3. Summary of + MetaVariables + </A> + </H3> + <P> + Servers MUST provide the following + metavariables to + scripts. See the individual descriptions for exceptions and semantics. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + CONTENT_LENGTH (section <A HREF="#6.1.2">6.1.2</A>) + CONTENT_TYPE (section <A HREF="#6.1.3">6.1.3</A>) + GATEWAY_INTERFACE (section <A HREF="#6.1.4">6.1.4</A>) + PATH_INFO (section <A HREF="#6.1.6">6.1.6</A>) + QUERY_STRING (section <A HREF="#6.1.8">6.1.8</A>) + REMOTE_ADDR (section <A HREF="#6.1.9">6.1.9</A>) + REQUEST_METHOD (section <A HREF="#6.1.13">6.1.13</A>) + SCRIPT_NAME (section <A HREF="#6.1.14">6.1.14</A>) + SERVER_NAME (section <A HREF="#6.1.15">6.1.15</A>) + SERVER_PORT (section <A HREF="#6.1.16">6.1.16</A>) + SERVER_PROTOCOL (section <A HREF="#6.1.17">6.1.17</A>) + SERVER_SOFTWARE (section <A HREF="#6.1.18">6.1.18</A>) + </PRE> + <P> + Servers SHOULD define the following + metavariables for scripts. + See the individual descriptions for exceptions and semantics. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + AUTH_TYPE (section <A HREF="#6.1.1">6.1.1</A>) + REMOTE_HOST (section <A HREF="#6.1.10">6.1.10</A>) + </PRE> + <P> + In addition, servers SHOULD provide + metavariables for all fields present + in the HTTP request header, with the exception of those involved with + access control. Servers MAY at their discretion provide + metavariables + for access control fields. + </P> + <P> + Servers MAY define the following + metavariables. See the individual + descriptions for exceptions and semantics. + </P><!--#if expr="! $GUI" --> + <P></P><!--#endif --> + <PRE> + PATH_TRANSLATED (section <A HREF="#6.1.7">6.1.7</A>) + REMOTE_IDENT (section <A HREF="#6.1.11">6.1.11</A>) + REMOTE_USER (section <A HREF="#6.1.12">6.1.12</A>) + </PRE> + <P> + Servers MAY + at their discretion define additional implementation-specific + extension metavariables + provided their names do not + conflict with defined header field names. Implementation-specific + metavariable names SHOULD + be prefixed with "X_" (<EM>e.g.</EM>, + "X_DBA") to avoid the potential for such conflicts. + </P> + + <H2> + <A NAME="9.0"> + 9. + Script Implementation + </A> + </H2> + <P> + This section defines the requirements and recommendations for scripts + that are intended to function in a CGI/1.1 environment. It is intended + primarily as a reference for script authors, but server implementors + should be familiar with these issues as well. + </P> + + <H3> + <A NAME="9.1"> + 9.1. Requirements for Scripts + </A> + </H3> + <P> + Scripts using the parsed-header method to communicate with servers + MUST supply a response header to the server. + (See <A HREF="#7.0">section 7</A>.) + </P> + <P> + Scripts using the NPH method to communicate with servers MUST + provide complete HTTP responses, and MUST use the value of the + SERVER_PROTOCOL metavariable + to determine the appropriate format. + (See <A HREF="#7.1">section 7.1</A>.) + </P> + <P> + Scripts MUST check the value of the REQUEST_METHOD + metavariable in order + to provide an appropriate response. + (See <A HREF="#6.1.13">section 6.1.13</A>.) + </P> + <P> + Scripts MUST be prepared to handled URL-encoded values in + metavariables. + In addition, they MUST recognise both "+" and "%20" in URL-encoded + quantities as representing the space character. + (See <A HREF="#3.1">section 3.1</A>.) + </P> + <P> + Scripts MUST ignore leading zeros in the major and minor version numbers + in the GATEWAY_INTERFACE + metavariable value. (See + <A HREF="#6.1.4">section 6.1.4</A>.) + </P> + <P> + When processing requests that include a + message-body, scripts + MUST NOT read more than CONTENT_LENGTH bytes from the input stream. + (See sections <A HREF="#6.1.2">6.1.2</A> and <A HREF="#6.2">6.2</A>.) + </P> + + <H3> + <A NAME="9.2"> + 9.2. Recommendations for Scripts + </A> + </H3> + <P> + Servers may interrupt or terminate script execution at any time + and without warning, so scripts SHOULD be prepared to deal with + abnormal termination. + </P> + <P> + Scripts MUST + reject with + error '405 Method Not + Allowed' requests + made using methods that they do not support. If the script does + not intend + processing the PATH_INFO data, then it SHOULD reject the request with + '404 Not + Found' if PATH_INFO is not NULL. + </P> + <P> + If a script is processing the output of a form, it SHOULD + verify that the CONTENT_TYPE + is "<SAMP>application/x-www-form-urlencoded</SAMP>" [<A HREF="#[2]">2</A>] + or whatever other media type is expected. + </P> + <P> + Scripts parsing PATH_INFO, + PATH_TRANSLATED, or SCRIPT_NAME + SHOULD be careful + of void path segments ("<SAMP>//</SAMP>") and special path segments + (<SAMP>"."</SAMP> and + <SAMP>".."</SAMP>). They SHOULD either be removed from the path before + use in OS + system calls, or the request SHOULD be rejected with + '404 Not Found'. + </P> + <P> + As it is impossible for + scripts to determine the client URI that + initiated a + request without knowledge of the specific server in + use, the script SHOULD NOT return "<SAMP>text/html</SAMP>" + documents containing + relative URL links without including a "<SAMP><BASE></SAMP>" + tag in the document. + </P> + <P> + When returning header fields, + scripts SHOULD try to send the CGI + header fields (see section + <A HREF="#7.2">7.2</A>) as soon as possible, and + SHOULD send them + before any HTTP header fields. This may + help reduce the server's memory requirements. + </P> + + <H2> + <A NAME="10.0"> + 10. System Specifications + </A> + </H2> + + <H3> + <A NAME="10.1"> + 10.1. AmigaDOS + </A> + </H3> + <P> + The implementation of the CGI on an AmigaDOS operating system platform + SHOULD use environment variables as the mechanism of providing + request metadata to CGI scripts. + </P> + <DL> + <DT><STRONG>Environment variables</STRONG> + </DT> + <DD> + <P> + These are accessed by the DOS library routine <SAMP>GetVar</SAMP>. The + flags argument SHOULD be 0. Case is ignored, but upper case is + recommended for compatibility with case-sensitive systems. + </P> + </DD> + <DT><STRONG>The current working directory</STRONG> + </DT> + <DD> + <P> + The current working directory for the script is set to the directory + containing the script. + </P> + </DD> + <DT><STRONG>Character set</STRONG> + </DT> + <DD> + <P> + The US-ASCII character set is used for the definition of environment + variable names and header + field names; the newline (NL) sequence is LF; + servers SHOULD also accept CR LF as a newline. + </P> + </DD> + </DL> + + <H3> + <A NAME="10.2"> + 10.2. Unix + </A> + </H3> + <P> + The implementation of the CGI on a UNIX operating system platform + SHOULD use environment variables as the mechanism of providing + request metadata to CGI scripts. + </P> + <P> + For Unix compatible operating systems, the following are defined: + </P> + <DL> + <DT><STRONG>Environment variables</STRONG> + </DT> + <DD> + <P> + These are accessed by the C library routine <SAMP>getenv</SAMP>. + </P> + </DD> + <DT><STRONG>The command line</STRONG> + </DT> + <DD> + <P> + This is accessed using the + <SAMP>argc</SAMP> and <SAMP>argv</SAMP> + arguments to <SAMP>main()</SAMP>. The words have any characters + that + are 'active' in the Bourne shell escaped with a backslash. + If the value of the QUERY_STRING + metavariable + contains an unencoded equals-sign '=', then the command line + SHOULD NOT be used by the script. + </P> + </DD> + <DT><STRONG>The current working directory</STRONG> + </DT> + <DD> + <P> + The current working directory for the script + SHOULD be set to the directory + containing the script. + </P> + </DD> + <DT><STRONG>Character set</STRONG> + </DT> + <DD> + <P> + The US-ASCII character set is used for the definition of environment + variable names and header field names; the newline (NL) sequence is LF; + servers SHOULD also accept CR LF as a newline. + </P> + </DD> + </DL> + + <H2> + <A NAME="11.0"> + 11. Security Considerations + </A> + </H2> + + <H3> + <A NAME="11.1"> + 11.1. Safe Methods + </A> + </H3> + <P> + As discussed in the security considerations of the HTTP + specifications [<A HREF="#[3]">3</A>,<A HREF="#[8]">8</A>], the + convention has been established that the + GET and HEAD methods should be 'safe'; they should cause no + side-effects and only have the significance of resource retrieval. + </P> + <P> + CGI scripts are responsible for enforcing any HTTP security considerations + [<A HREF="#[3]">3</A>,<A HREF="#[8]">8</A>] + with respect to the protocol version level of the request and + any side effects generated by the scripts on behalf of + the server. Primary + among these + are the considerations of safe and idempotent methods. Idempotent + requests are those that may be repeated an arbitrary number of times + and produce side effects identical to a single request. + </P> + + <H3> + <A NAME="11.2"> + 11.2. HTTP Header + Fields Containing Sensitive Information + </A> + </H3> + <P> + Some HTTP header fields may carry sensitive information which the server + SHOULD NOT pass on to the script unless explicitly configured to do + so. For example, if the server protects the script using the + "<SAMP>Basic</SAMP>" + authentication scheme, then the client will send an + "<SAMP>Authorization</SAMP>" + header field containing a username and password. If the server, rather + than the script, validates this information then the password SHOULD + NOT be passed on to the script <EM>via</EM> the HTTP_AUTHORIZATION + metavariable + without careful consideration. + This also applies to the + Proxy-Authorization header field and the corresponding + HTTP_PROXY_AUTHORIZATION + metavariable. + </P> + + <H3> + <A NAME="11.3"> + 11.3. Script + Interference with the Server + </A> + </H3> + <P> + The most common implementation of CGI invokes the script as a child + process using the same user and group as the server process. It + SHOULD therefore be ensured that the script cannot interfere with the + server process, its configuration, or documents. + </P> + <P> + If the script is executed by calling a function linked in to the + server software (either at compile-time or run-time) then precautions + SHOULD be taken to protect the core memory of the server, or to + ensure that untrusted code cannot be executed. + </P> + + <H3> + <A NAME="11.4"> + 11.4. Data Length and Buffering Considerations + </A> + </H3> + <P> + This specification places no limits on the length of message-bodies + presented to the script. Scripts should not assume that statically + allocated buffers of any size are sufficient to contain the entire + submission at one time. Use of a fixed length buffer without careful + overflow checking may result in an attacker exploiting 'stack-smashing' + or 'stack-overflow' vulnerabilities of the operating system. + Scripts may spool large submissions to disk or other buffering media, + but a rapid succession of large submissions may result in denial of + service conditions. If the CONTENT_LENGTH of a message-body is larger + than resource considerations allow, scripts should respond with an + error status appropriate for the protocol version; potentially applicable + status codes include '503 Service Unavailable' (HTTP/1.0 and HTTP/1.1), + '413 Request Entity Too Large' (HTTP/1.1), and + '414 Request-URI Too Long' (HTTP/1.1). + </P> + + <H3> + <A NAME="11.5"> + 11.5. Stateless Processing + </A> + </H3> + <P> + The stateless nature of the Web makes each script execution and resource + retrieval independent of all others even when multiple requests constitute a + single conceptual Web transaction. Because of this, a script should not + make any assumptions about the context of the user-agent submitting a + request. In particular, scripts should examine data obtained from the client + and verify that they are valid, both in form and content, before allowing + them to be used for sensitive purposes such as input to other + applications, commands, or operating system services. These uses + include, but are not + limited to: system call arguments, database writes, dynamically evaluated + source code, and input to billing or other secure processes. It is important + that applications be protected from invalid input regardless of whether + the invalidity is the result of user error, logic error, or malicious action. + </P> + <P> + Authors of scripts involved in multi-request transactions should be + particularly cautios about validating the state information; + undesirable effects may result from the substitution of dangerous + values for portions of the submission which might otherwise be + presumed safe. Subversion of this type occurs when alterations + are made to data from a prior stage of the transaction that were + not meant to be controlled by the client (<EM>e.g.</EM>, hidden + HTML form elements, cookies, embedded URLs, <EM>etc.</EM>). + </P> + + <H2> + <A NAME="12.0"> + 12. Acknowledgements + </A> + </H2> + <P> + This work is based on a draft published in 1997 by David R. Robinson, + which in turn was based on the original CGI interface that arose out of + discussions on the <EM>www-talk</EM> mailing list. In particular, + Rob McCool, John Franks, Ari Luotonen, + George Phillips and + Tony Sanders deserve special recognition for their efforts in + defining and implementing the early versions of this interface. + </P> + <P> + This document has also greatly benefited from the comments and + suggestions made by Chris Adie, Dave Kristol, + Mike Meyer, David Morris, Jeremy Madea, + Patrick M<SUP>c</SUP>Manus, Adam Donahue, + Ross Patterson, and Harald Alvestrand. + </P> + + <H2> + <A NAME="13.0"> + 13. References + </A> + </H2> + <DL COMPACT> + <DT><A NAME="[1]">[1]</A> + </DT> + <DD>Berners-Lee, T., 'Universal Resource Identifiers in WWW: A + Unifying Syntax for the Expression of Names and Addresses of + Objects on the Network as used in the World-Wide Web', RFC 1630, + CERN, June 1994. + <P> + </P> + </DD> + <DT><A NAME="[2]">[2]</A> + </DT> + <DD>Berners-Lee, T. and Connolly, D., 'Hypertext Markup Language - + 2.0', RFC 1866, MIT/W3C, November 1995. + <P> + </P> + </DD> + <DT><A NAME="[3]">[3]</A> + </DT> + <DD>Berners-Lee, T., Fielding, R. T. and Frystyk, H., + 'Hypertext Transfer Protocol -- HTTP/1.0', RFC 1945, MIT/LCS, + UC Irvine, May 1996. + <P> + </P> + </DD> + + <DT><A NAME="[4]">[4]</A> + </DT> + <DD>Berners-Lee, T., Fielding, R., and Masinter, L., Editors, + 'Uniform Resource Identifiers (URI): Generic Syntax', RFC 2396, + MIT, U.C. Irvine, Xerox Corporation, August 1996. + <P> + </P> + </DD> + + <DT><A NAME="[5]">[5]</A> + </DT> + <DD>Braden, R., Editor, 'Requirements for Internet Hosts -- + Application and Support', STD 3, RFC 1123, IETF, October 1989. + <P> + </P> + </DD> + <DT><A NAME="[6]">[6]</A> + </DT> + <DD>Crocker, D.H., 'Standard for the Format of ARPA Internet Text + Messages', STD 11, RFC 822, University of Delaware, August 1982. + <P> + </P> + </DD> + <DT><A NAME="[7]">[7]</A> + </DT> + <DD>Fielding, R., 'Relative Uniform Resource Locators', RFC 1808, + UC Irvine, June 1995. + <P> + </P> + </DD> + <DT><A NAME="[8]">[8]</A> + </DT> + <DD>Fielding, R., Gettys, J., Mogul, J., Frystyk, H. and + Berners-Lee, T., 'Hypertext Transfer Protocol -- HTTP/1.1', + RFC 2068, UC Irvine, DEC, + MIT/LCS, January 1997. + <P> + </P> + </DD> + <DT><A NAME="[9]">[9]</A> + </DT> + <DD>Freed, N. and Borenstein N., 'Multipurpose Internet Mail + Extensions (MIME) Part Two: Media Types', RFC 2046, Innosoft, + First Virtual, November 1996. + <P> + </P> + </DD> + <DT><A NAME="[10]">[10]</A> + </DT> + <DD>Mockapetris, P., 'Domain Names - Concepts and Facilities', + STD 13, RFC 1034, ISI, November 1987. + <P> + </P> + </DD> + <DT><A NAME="[11]">[11]</A> + </DT> + <DD>St. Johns, M., 'Identification Protocol', RFC 1431, US + Department of Defense, February 1993. + <P> + </P> + </DD> + <DT><A NAME="[12]">[12]</A> + </DT> + <DD>'Coded Character Set -- 7-bit American Standard Code for + Information Interchange', ANSI X3.4-1986. + <P> + </P> + </DD> + <DT><A NAME="[13]">[13]</A> + </DT> + <DD>Hinden, R. and Deering, S., + 'IP Version 6 Addressing Architecture', RFC 2373, + Nokia, Cisco Systems, + July 1998. + <P> + </P> + </DD> + </DL> + + <H2> + <A NAME="14.0"> + 14. Authors' Addresses + </A> + </H2> + <ADDRESS> + <P> + Ken A L Coar + <BR> + MeepZor Consulting + <BR> + 7824 Mayfaire Crest Lane, Suite 202 + <BR> + Raleigh, NC 27615-4875 + <BR> + U.S.A. + </P> + <P> + Tel: +1 (919) 254.4237 + <BR> + Fax: +1 (919) 254.5250 + <BR> + Email: + <A + HREF="mailto:Ken.Coar@Golux.Com" + ><SAMP>Ken.Coar@Golux.Com</SAMP></A> + </P> + </ADDRESS> + <ADDRESS> + <P> + David Robinson + <BR> + E*TRADE UK Ltd + <BR> + Mount Pleasant House + <BR> + 2 Mount Pleasant + <BR> + Huntingdon Road + <BR> + Cambridge CB3 0RN + <BR> + UK + </P> + <P> + Tel: +44 (1223) 566926 + <BR> + Fax: +44 (1223) 506288 + <BR> + Email: + <A + HREF="mailto:drtr@etrade.co.uk" + ><SAMP>drtr@etrade.co.uk</SAMP></A> + </ADDRESS> + + </BODY> +</HTML> |