| /* 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; |
| } |