/* vi: set sw=4 ts=4: */ /* * bare bones sendmail * * Copyright (C) 2008 by Vladimir Dronnikov * * Licensed under GPLv2, see file LICENSE in this tarball for details. */ #include "libbb.h" struct globals { pid_t helper_pid; unsigned timeout; FILE *fp0; // initial stdin // arguments for SSL connection helper const char *xargs[9]; }; #define G (*ptr_to_globals) #define helper_pid (G.helper_pid) #define timeout (G.timeout ) #define fp0 (G.fp0 ) #define xargs (G.xargs ) #define INIT_G() do { \ SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \ xargs[0] = "openssl"; \ xargs[1] = "s_client"; \ xargs[2] = "-quiet"; \ xargs[3] = "-connect"; \ /*xargs[4] = "localhost";*/ \ xargs[5] = "-tls1"; \ xargs[6] = "-starttls"; \ xargs[7] = "smtp"; \ } while (0) #define opt_connect (xargs[4]) static void uuencode(char *fname, const char *text) { enum { SRC_BUF_SIZE = 45, /* This *MUST* be a multiple of 3 */ DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3), }; #define src_buf text FILE *fp = fp; ssize_t len = len; char dst_buf[DST_BUF_SIZE + 1]; if (fname) { fp = (NOT_LONE_DASH(fname)) ? xfopen_for_read(fname) : fp0; src_buf = bb_common_bufsiz1; // N.B. strlen(NULL) segfaults! } else if (text) { // though we do not call uuencode(NULL, NULL) explicitly // still we do not want to break things suddenly len = strlen(text); } else return; while (1) { size_t size; if (fname) { size = fread((char *)src_buf, 1, SRC_BUF_SIZE, fp); if ((ssize_t)size < 0) bb_perror_msg_and_die(bb_msg_read_error); } else { size = len; if (len > SRC_BUF_SIZE) size = SRC_BUF_SIZE; } if (!size) break; // encode the buffer we just read in bb_uuencode(dst_buf, src_buf, size, bb_uuenc_tbl_base64); if (fname) { printf("\r\n"); } else { src_buf += size; len -= size; } fwrite(dst_buf, 1, 4 * ((size + 2) / 3), stdout); } if (fname) fclose(fp); #undef src_buf } #if ENABLE_FEATURE_SENDMAIL_SSL static void kill_helper(void) { // TODO!!!: is there more elegant way to terminate child on program failure? if (helper_pid > 0) kill(helper_pid, SIGTERM); } // generic signal handler static void signal_handler(int signo) { #define err signo if (SIGALRM == signo) { kill_helper(); bb_error_msg_and_die("timed out"); } // SIGCHLD. reap zombies if (wait_any_nohang(&err) > 0) if (WIFEXITED(err)) { // if (WEXITSTATUS(err)) bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err)); // else // kill(0, SIGCONT); } #undef err } static void launch_helper(const char **argv) { // setup vanilla unidirectional pipes interchange int idx; int pipes[4]; xpipe(pipes); xpipe(pipes+2); helper_pid = vfork(); if (helper_pid < 0) bb_perror_msg_and_die("vfork"); idx = (!helper_pid) * 2; xdup2(pipes[idx], STDIN_FILENO); xdup2(pipes[3-idx], STDOUT_FILENO); if (ENABLE_FEATURE_CLEAN_UP) for (int i = 4; --i >= 0; ) if (pipes[i] > STDOUT_FILENO) close(pipes[i]); if (!helper_pid) { // child: try to execute connection helper BB_EXECVP(*argv, (char **)argv); _exit(127); } // parent: check whether child is alive bb_signals(0 + (1 << SIGCHLD) + (1 << SIGALRM) , signal_handler); signal_handler(SIGCHLD); // child seems OK -> parent goes on } #else #define kill_helper() ((void)0) #define launch_helper(x) bb_error_msg_and_die("no SSL support") #endif static const char *command(const char *fmt, const char *param) { const char *msg = fmt; alarm(timeout); if (msg) { msg = xasprintf(fmt, param); printf("%s\r\n", msg); } fflush(stdout); return msg; } static int smtp_checkp(const char *fmt, const char *param, int code) { char *answer; const char *msg = command(fmt, param); // read stdin // if the string has a form \d\d\d- -- read next string. E.g. EHLO response // parse first bytes to a number // if code = -1 then just return this number // if code != -1 then checks whether the number equals the code // if not equal -> die saying msg while ((answer = xmalloc_fgetline(stdin)) != NULL) if (strlen(answer) <= 3 || '-' != answer[3]) break; if (answer) { int n = atoi(answer); alarm(0); free(answer); if (-1 == code || n == code) return n; } kill_helper(); bb_error_msg_and_die("%s failed", msg); } static inline int smtp_check(const char *fmt, int code) { return smtp_checkp(fmt, NULL, code); } // strip argument of bad chars static char *sane(char *str) { char *s = str; char *p = s; while (*s) { if (isalnum(*s) || '_' == *s || '-' == *s || '.' == *s || '@' == *s) { *p++ = *s; } s++; } *p = '\0'; return str; } // NB: parse_url can modify url[] (despite const), but only if '@' is there static const char *parse_url(const char *url, const char **user, const char **pass) { // parse [user[:pass]@]host // return host char *s = strchr(url, '@'); *user = *pass = NULL; if (s) { *s++ = '\0'; *user = url; url = s; s = strchr(*user, ':'); if (s) { *s++ = '\0'; *pass = s; } } return url; } static void rcptto(const char *s) { smtp_checkp("RCPT TO:<%s>", s, 250); } int sendmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int sendmail_main(int argc UNUSED_PARAM, char **argv) { #if ENABLE_FEATURE_SENDMAIL_MAILX llist_t *opt_attachments = NULL; const char *opt_subject; const char *opt_charset = CONFIG_FEATURE_SENDMAIL_CHARSET; #if ENABLE_FEATURE_SENDMAIL_MAILXX llist_t *opt_carboncopies = NULL; char *opt_errors_to; #endif #endif char *opt_from, *opt_fullname; const char *opt_user; const char *opt_pass; int code; char *boundary; llist_t *l; llist_t *headers = NULL; char *domain = sane(safe_getdomainname()); unsigned opts; enum { OPT_w = 1 << 0, // network timeout OPT_H = 1 << 1, // [user:password@]server[:port] OPT_S = 1 << 2, // connect using openssl s_client helper OPT_t = 1 << 3, // read message for recipients OPT_N = 1 << 4, // request notification OPT_f = 1 << 5, // sender address OPT_F = 1 << 6, // sender name, overrides $NAME #if ENABLE_FEATURE_SENDMAIL_MAILX OPT_s = 1 << 7, // subject OPT_j = 1 << 8, // assumed charset OPT_a = 1 << 9, // attachment(s) #if ENABLE_FEATURE_SENDMAIL_MAILXX OPT_c = 1 << 10, // carbon copy OPT_e = 1 << 11, // errors-to address #endif #endif }; // init global variables INIT_G(); // save initial stdin since body is piped! xdup2(STDIN_FILENO, 3); fp0 = fdopen(3, "r"); // parse options opt_complementary = "w+:a::" USE_FEATURE_SENDMAIL_MAILXX("c::"); opts = getopt32(argv, "w:H:St" "N:f:F:" USE_FEATURE_SENDMAIL_MAILX("s:j:a:") USE_FEATURE_SENDMAIL_MAILXX("c:e:") "X:V:vq:R:O:o:nmL:Iih:GC:B:b:A:" // postfix compat only, ignored // r:Q:p:M:Dd are candidates from another man page. TODO? "46E", // ssmtp introduces another quirks. TODO?: -a[upm] (user, pass, method) to be supported &timeout /* -w */, &opt_connect /* -H */, NULL, &opt_from, &opt_fullname, USE_FEATURE_SENDMAIL_MAILX(&opt_subject, &opt_charset, &opt_attachments,) USE_FEATURE_SENDMAIL_MAILXX(&opt_carboncopies, &opt_errors_to,) NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL ); //argc -= optind; argv += optind; // connect to server // host[:port] not specified ? -> use $SMTPHOST. no $SMTPHOST ? -> use localhost if (!(opts & OPT_H)) { opt_connect = getenv("SMTPHOST"); if (!opt_connect) opt_connect = "127.0.0.1"; } // fetch username and password, if any // NB: parse_url modifies opt_connect[] ONLY if '@' is there. // Thus "127.0.0.1" won't be modified, an is ok that it is RO. opt_connect = parse_url(opt_connect, &opt_user, &opt_pass); // username must be defined! if (!opt_user) { // N.B. IMHO getenv("USER") can be way easily spoofed! opt_user = bb_getpwuid(NULL, -1, getuid()); } // SSL ordered? -> if (opts & OPT_S) { // ... use openssl helper launch_helper(xargs); // no SSL ordered? -> } else { // ... make plain connect int fd = create_and_connect_stream_or_die(opt_connect, 25); // make ourselves a simple IO filter // from now we know nothing about network :) xmove_fd(fd, STDIN_FILENO); xdup2(STDIN_FILENO, STDOUT_FILENO); } // got no sender address? -> use username as a resort if (!(opts & OPT_f)) { opt_from = xasprintf("%s@%s", opt_user, domain); } // introduce to server // we didn't use SSL helper? -> if (!(opts & OPT_S)) { // ... wait for initial server OK smtp_check(NULL, 220); } // we should start with modern EHLO if (250 != smtp_checkp("EHLO %s", domain, -1)) { smtp_checkp("HELO %s", domain, 250); } if (ENABLE_FEATURE_CLEAN_UP) free(domain); // set sender // NOTE: if password has not been specified // then no authentication is possible code = (opt_pass ? -1 : 250); // first try softly without authentication while (250 != smtp_checkp("MAIL FROM:<%s>", opt_from, code)) { // MAIL FROM failed -> authentication needed if (334 == smtp_check("AUTH LOGIN", -1)) { uuencode(NULL, opt_user); // opt_user != NULL smtp_check("", 334); uuencode(NULL, opt_pass); smtp_check("", 235); } // authenticated OK? -> retry to set sender // but this time die on failure! code = 250; } // recipients specified as arguments while (*argv) { char *s = sane(*argv); // loose test on email address validity if (strchr(s, '@')) { rcptto(s); llist_add_to_end(&headers, xasprintf("To: %s", s)); } argv++; } #if ENABLE_FEATURE_SENDMAIL_MAILXX // carbon copies recipients specified as -c options for (l = opt_carboncopies; l; l = l->link) { char *s = sane(l->data); // loose test on email address validity if (strchr(s, '@')) { rcptto(s); // TODO: do we ever need to mangle the message? //llist_add_to_end(&headers, xasprintf("Cc: %s", s)); } } #endif // if -t specified or no recipients specified -> read recipients from message // i.e. scan stdin for To:, Cc:, Bcc: lines ... // ... and then use the rest of stdin as message body // N.B. subject read from body can be further overrided with one specified on command line. // recipients are merged. Bcc: lines are deleted // N.B. other headers are collected and will be dumped verbatim if (opts & OPT_t || !headers) { // fetch recipients and (optionally) subject char *s; while ((s = xmalloc_fgetline(fp0)) != NULL) { if (0 == strncasecmp("To: ", s, 4) || 0 == strncasecmp("Cc: ", s, 4)) { rcptto(sane(s+4)); llist_add_to_end(&headers, s); } else if (0 == strncasecmp("Bcc: ", s, 5)) { rcptto(sane(s+5)); free(s); // N.B. Bcc vanishes from headers! } else if (0 == strncmp("Subject: ", s, 9)) { // we read subject -> use it verbatim unless it is specified // on command line #if ENABLE_FEATURE_SENDMAIL_MAILX if (opts & OPT_s) free(s); else #endif llist_add_to_end(&headers, s); } else if (s[0]) { // misc header llist_add_to_end(&headers, s); } else { free(s); break; // stop on the first empty line } } } // enter "put message" mode smtp_check("DATA", 354); // put headers we could have preread with -t for (l = headers; l; l = l->link) { printf("%s\r\n", l->data); if (ENABLE_FEATURE_CLEAN_UP) free(l->data); } // put (possibly encoded) subject #if ENABLE_FEATURE_SENDMAIL_MAILX if (opts & OPT_j) sane((char *)opt_charset); if (opts & OPT_s) { printf("Subject: "); if (opts & OPT_j) { printf("=?%s?B?", opt_charset); uuencode(NULL, opt_subject); printf("?="); } else { printf("%s", opt_subject); } printf("\r\n"); } #endif // put sender name, $NAME is the default if (!(opts & OPT_F)) opt_fullname = getenv("NAME"); if (opt_fullname) printf("From: \"%s\" <%s>\r\n", opt_fullname, opt_from); // put notification if (opts & OPT_N) printf("Disposition-Notification-To: %s\r\n", opt_from); #if ENABLE_FEATURE_SENDMAIL_MAILXX // put errors recipient if (opts & OPT_e) printf("Errors-To: %s\r\n", opt_errors_to); #endif // make a random string -- it will delimit message parts srand(monotonic_us()); boundary = xasprintf("%d-%d-%d", rand(), rand(), rand()); // put common headers // TODO: do we really need this? // printf("Message-ID: <%s>\r\n", boundary); #if ENABLE_FEATURE_SENDMAIL_MAILX // have attachments? -> compose multipart MIME if (opt_attachments) { const char *fmt; const char *p; char *q; printf( "Mime-Version: 1.0\r\n" "%smultipart/mixed; boundary=\"%s\"\r\n" , "Content-Type: " , boundary ); // body is pseudo attachment read from stdin in first turn llist_add_to(&opt_attachments, (char *)"-"); // put body + attachment(s) // N.B. all these weird things just to be tiny // by reusing string patterns! fmt = "\r\n--%s\r\n" "%stext/plain; charset=%s\r\n" "%s%s\r\n" "%s" ; p = opt_charset; q = (char *)""; l = opt_attachments; while (l) { printf( fmt , boundary , "Content-Type: " , p , "Content-Disposition: inline" , q , "Content-Transfer-Encoding: base64\r\n" ); p = ""; fmt = "\r\n--%s\r\n" "%sapplication/octet-stream%s\r\n" "%s; filename=\"%s\"\r\n" "%s" ; uuencode(l->data, NULL); l = l->link; if (l) q = bb_get_last_path_component_strip(l->data); } // put message terminator printf("\r\n--%s--\r\n" "\r\n", boundary); // no attachments? -> just dump message } else #endif { char *s; // terminate headers printf("\r\n"); // put plain text respecting leading dots while ((s = xmalloc_fgetline(fp0)) != NULL) { // escape leading dots // N.B. this feature is implied even if no -i (-oi) switch given // N.B. we need to escape the leading dot regardless of // whether it is single or not character on the line if ('.' == s[0] /*&& '\0' == s[1] */) printf("."); // dump read line printf("%s\r\n", s); } } // leave "put message" mode smtp_check(".", 250); // ... and say goodbye smtp_check("QUIT", 221); // cleanup if (ENABLE_FEATURE_CLEAN_UP) fclose(fp0); return EXIT_SUCCESS; }