diff options
Diffstat (limited to 'wget.c')
| -rw-r--r-- | wget.c | 264 |
1 files changed, 264 insertions, 0 deletions
@@ -0,0 +1,264 @@ +/* vi: set sw=4 ts=4: */ +/* + * wget - retrieve a file using HTTP + * + * Chip Rosenthal + * Covad Communications + * <chip@laserlink.net> + */ + +#include "internal.h" +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <ctype.h> +#include <string.h> + +#include <sys/types.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <netinet/in.h> +#include <arpa/inet.h> +#include <netdb.h> + + +void parse_url(char *url, char **uri_host, int *uri_port, char **uri_path); +FILE *open_socket(char *host, int port); +char *gethdr(char *buf, size_t bufsiz, FILE *fp, int *istrunc); + + +int wget_main(int argc, char **argv) +{ + FILE *sfp; /* socket to web server */ + char *uri_host, *uri_path; /* parsed from command line url */ + int uri_port; + char *s, buf[512]; + int n; + + char *fname_out = NULL; /* where to direct output (-O) */ + int do_continue = 0; /* continue a prev transfer (-c) */ + long beg_range = 0L; /* range at which continue begins */ + int got_clen = 0; /* got content-length: from server */ + long clen = 1L; /* the content length */ + + /* + * Crack command line. + */ + while ((n = getopt(argc, argv, "cO:")) != EOF) { + switch (n) { + case 'c': + ++do_continue; + break; + case 'O': + fname_out = optarg; + break; + default: + usage(wget_usage); + } + } + if (do_continue && !fname_out) + fatalError("wget: cannot specify continue (-c) without a filename (-O)\n"); + if (argc - optind != 1) + usage(wget_usage); + /* + * Parse url into components. + */ + parse_url(argv[optind], &uri_host, &uri_port, &uri_path); + + /* + * Open socket to server. + */ + sfp = open_socket(uri_host, uri_port); + + /* + * Open the output stream. + */ + if (fname_out != NULL) { + /* Check if the file is supposed to go to stdout */ + if (!strcmp(fname_out, "-") == 0) { + /* Nope -- so open the output file */ + if (freopen(fname_out, (do_continue ? "a" : "w"), stdout) == NULL) + fatalError("wget: freopen(%s): %s\n", fname_out, strerror(errno)); + } + } + + /* + * Determine where to start transfer. + */ + if (do_continue) { + struct stat sbuf; + if (fstat(fileno(stdout), &sbuf) < 0) + fatalError("wget: fstat(): %s\n", strerror(errno)); + if (sbuf.st_size > 0) + beg_range = sbuf.st_size; + else + do_continue = 0; + } + + /* + * Send HTTP request. + */ + fprintf(sfp, "GET %s HTTP/1.1\r\nHost: %s\r\n", uri_path, uri_host); + if (do_continue) + fprintf(sfp, "Range: bytes=%ld-\r\n", beg_range); + fputs("Connection: close\r\n\r\n", sfp); + + /* + * Retrieve HTTP response line and check for "200" status code. + */ + if (fgets(buf, sizeof(buf), sfp) == NULL) + fatalError("wget: no response from server\n"); + for (s = buf ; *s != '\0' && !isspace(*s) ; ++s) + ; + for ( ; isspace(*s) ; ++s) + ; + switch (atoi(s)) { + case 200: + if (!do_continue) + break; + fatalError("wget: cannot continue - server does not properly support ranges\n"); + case 206: + if (do_continue) + break; + /*FALLTHRU*/ + default: + fatalError("wget: server returned error: %s", buf); + } + + /* + * Retrieve HTTP headers. + */ + while ((s = gethdr(buf, sizeof(buf), sfp, &n)) != NULL) { + if (strcmp(buf, "content-length") == 0) { + clen = atol(s); + got_clen = 1; + continue; + } + if (strcmp(buf, "transfer-encoding") == 0) { + fatalError("wget: i do not do transfer encodings, server wants to do: %s\n", s); + continue; + } + } + + /* + * Retrieve HTTP body. + */ + while (clen > 0 && (n = fread(buf, 1, sizeof(buf), sfp)) > 0) { + fwrite(buf, 1, n, stdout); + if (got_clen) + clen -= n; + } + if (n == 0 && ferror(sfp)) + fatalError("wget: network read error: %s", strerror(errno)); + + exit(0); +} + + +void parse_url(char *url, char **uri_host, int *uri_port, char **uri_path) +{ + char *s, *h; + + *uri_port = 80; + + if (strncmp(url, "http://", 7) != 0) + fatalError("wget: not an http url: %s\n", url); + + /* pull the host portion to the front of the buffer */ + for (s = url, h = url+7 ; *h != '/' ; ++h) { + if (*h == '\0') + fatalError("wget: cannot parse url: %s\n", url); + if (*h == ':') { + *uri_port = atoi(h+1); + *h = '\0'; + } + *s++ = *h; + } + *s = '\0'; + *uri_host = url; + *uri_path = h; +} + + +FILE *open_socket(char *host, int port) +{ + struct sockaddr_in sin; + struct hostent *hp; + int fd; + FILE *fp; + + memzero(&sin, sizeof(sin)); + sin.sin_family = AF_INET; + if ((hp = (struct hostent *) gethostbyname(host)) == NULL) + fatalError("wget: cannot resolve %s\n", host); + memcpy(&sin.sin_addr, hp->h_addr_list[0], hp->h_length); + sin.sin_port = htons(port); + + /* + * Get the server onto a stdio stream. + */ + if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) + fatalError("wget: socket(): %s\n", strerror(errno)); + if (connect(fd, (struct sockaddr *) &sin, sizeof(sin)) < 0) + fatalError("wget: connect(%s): %s\n", host, strerror(errno)); + if ((fp = fdopen(fd, "r+")) == NULL) + fatalError("wget: fdopen(): %s\n", strerror(errno)); + + return fp; +} + + +char *gethdr(char *buf, size_t bufsiz, FILE *fp, int *istrunc) +{ + char *s, *hdrval; + int c; + + *istrunc = 0; + + /* retrieve header line */ + if (fgets(buf, bufsiz, fp) == NULL) + return NULL; + + /* see if we are at the end of the headers */ + for (s = buf ; *s == '\r' ; ++s) + ; + if (s[0] == '\n') + return NULL; + + /* convert the header name to lower case */ + for (s = buf ; isalnum(*s) || *s == '-' ; ++s) + *s = tolower(*s); + + /* verify we are at the end of the header name */ + if (*s != ':') + fatalError("wget: bad header line: %s\n", buf); + + /* locate the start of the header value */ + for (*s++ = '\0' ; *s == ' ' || *s == '\t' ; ++s) + ; + hdrval = s; + + /* locate the end of header */ + while (*s != '\0' && *s != '\r' && *s != '\n') + ++s; + + /* end of header found */ + if (*s != '\0') { + *s = '\0'; + return hdrval; + } + + /* Rat! The buffer isn't big enough to hold the entire header value. */ + while (c = getc(fp), c != EOF && c != '\n') + ; + *istrunc = 1; + return hdrval; +} + +/* +Local Variables: +c-file-style: "linux" +c-basic-offset: 4 +tab-width: 4 +End: +*/ |