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Diffstat (limited to 'mailutils/sendmail.c')
| -rw-r--r-- | mailutils/sendmail.c | 388 |
1 files changed, 388 insertions, 0 deletions
diff --git a/mailutils/sendmail.c b/mailutils/sendmail.c new file mode 100644 index 0000000..55555c3 --- /dev/null +++ b/mailutils/sendmail.c @@ -0,0 +1,388 @@ +/* vi: set sw=4 ts=4: */ +/* + * bare bones sendmail + * + * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com> + * + * Licensed under GPLv2, see file LICENSE in this tarball for details. + */ +#include "libbb.h" +#include "mail.h" + +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); + if (timeout) + alarm(0); + free(answer); + if (-1 == code || n == code) + return n; + } + bb_error_msg_and_die("%s failed", msg); +} + +static int smtp_check(const char *fmt, int code) +{ + return smtp_checkp(fmt, NULL, code); +} + +// strip argument of bad chars +static char *sane_address(char *str) +{ + char *s = str; + char *p = s; + while (*s) { + if (isalnum(*s) || '_' == *s || '-' == *s || '.' == *s || '@' == *s) { + *p++ = *s; + } + s++; + } + *p = '\0'; + return str; +} + +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; +#if ENABLE_FEATURE_SENDMAIL_MAILXX + llist_t *opt_carboncopies = NULL; + char *opt_errors_to; +#endif +#endif + char *opt_connect = opt_connect; + char *opt_from, *opt_fullname; + char *boundary; + llist_t *l; + llist_t *headers = NULL; + char *domain = sane_address(safe_getdomainname()); + int code; + + enum { + OPT_w = 1 << 0, // network timeout + OPT_t = 1 << 1, // read message for recipients + OPT_N = 1 << 2, // request notification + OPT_f = 1 << 3, // sender address + OPT_F = 1 << 4, // sender name, overrides $NAME + OPT_s = 1 << 5, // subject + OPT_j = 1 << 6, // assumed charset + OPT_a = 1 << 7, // attachment(s) + OPT_H = 1 << 8, // use external connection helper + OPT_S = 1 << 9, // specify connection string + OPT_c = 1 << 10, // carbon copy + OPT_e = 1 << 11, // errors-to address + }; + + // init global variables + INIT_G(); + + // save initial stdin since body is piped! + xdup2(STDIN_FILENO, 3); + G.fp0 = fdopen(3, "r"); + + // parse options + opt_complementary = "w+" USE_FEATURE_SENDMAIL_MAILX(":a::H--S:S--H") USE_FEATURE_SENDMAIL_MAILXX(":c::"); + opts = getopt32(argv, + "w:t" "N:f:F:" USE_FEATURE_SENDMAIL_MAILX("s:j:a:H:S:") 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 */, NULL, &opt_from, &opt_fullname, + USE_FEATURE_SENDMAIL_MAILX(&opt_subject, &G.opt_charset, &opt_attachments, &opt_connect, &opt_connect,) + 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 + +#if ENABLE_FEATURE_SENDMAIL_MAILX + // N.B. -H and -S are mutually exclusive so they do not spoil opt_connect + // connection helper ordered? -> + if (opts & OPT_H) { + const char *args[] = { "sh", "-c", opt_connect, NULL }; + // plug it in + launch_helper(args); + // vanilla connection + } else +#endif + { + int fd; + // host[:port] not explicitly specified ? -> use $SMTPHOST + // no $SMTPHOST ? -> use localhost + if (!(opts & OPT_S)) { + opt_connect = getenv("SMTPHOST"); + if (!opt_connect) + opt_connect = (char *)"127.0.0.1"; + } + // do connect + fd = create_and_connect_stream_or_die(opt_connect, 25); + // and make ourselves a simple IO filter + xmove_fd(fd, STDIN_FILENO); + xdup2(STDIN_FILENO, STDOUT_FILENO); + } + // N.B. from now we know nothing about network :) + + // wait for initial server OK + // N.B. if we used openssl the initial 220 answer is already swallowed during openssl TLS init procedure + // so we need to push the server to see whether we are ok + code = smtp_check("NOOP", -1); + // 220 on plain connection, 250 on openssl-helped TLS session + if (220 == code) + smtp_check(NULL, 250); // reread the code to stay in sync + else if (250 != code) + bb_error_msg_and_die("INIT failed"); + + // we should start with modern EHLO + if (250 != smtp_checkp("EHLO %s", domain, -1)) { + smtp_checkp("HELO %s", domain, 250); + } + + // set sender + // N.B. we have here a very loosely defined algotythm + // since sendmail historically offers no means to specify secrets on cmdline. + // 1) server can require no authentication -> + // we must just provide a (possibly fake) reply address. + // 2) server can require AUTH -> + // we must provide valid username and password along with a (possibly fake) reply address. + // For the sake of security username and password are to be read either from console or from a secured file. + // Since reading from console may defeat usability, the solution is either to read from a predefined + // file descriptor (e.g. 4), or again from a secured file. + + // got no sender address? -> use system username as a resort + if (!(opts & OPT_f)) { + // N.B. IMHO getenv("USER") can be way easily spoofed! + G.user = bb_getpwuid(NULL, -1, getuid()); + opt_from = xasprintf("%s@%s", G.user, domain); + } + if (ENABLE_FEATURE_CLEAN_UP) + free(domain); + + code = -1; // 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)) { + // we must read credentials + get_cred_or_die(4); + encode_base64(NULL, G.user, NULL); + smtp_check("", 334); + encode_base64(NULL, G.pass, NULL); + 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_address(*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_address(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(G.fp0)) != NULL) { + if (0 == strncasecmp("To: ", s, 4) || 0 == strncasecmp("Cc: ", s, 4)) { + rcptto(sane_address(s+4)); + llist_add_to_end(&headers, s); + } else if (0 == strncasecmp("Bcc: ", s, 5)) { + rcptto(sane_address(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 (!(opts & OPT_s)) + llist_add_to_end(&headers, s); + else + free(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_s) { + printf("Subject: "); + if (opts & OPT_j) { + printf("=?%s?B?", G.opt_charset); + encode_base64(NULL, opt_subject, NULL); + 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 = G.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" + ; + encode_base64(l->data, (const char *)G.fp0, "\r"); + 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(G.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(G.fp0); + + return EXIT_SUCCESS; +} |