diff options
Diffstat (limited to 'release/src/router/busybox/mailutils/sendmail.c')
| -rw-r--r-- | release/src/router/busybox/mailutils/sendmail.c | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/release/src/router/busybox/mailutils/sendmail.c b/release/src/router/busybox/mailutils/sendmail.c new file mode 100644 index 00000000..7e57a94c --- /dev/null +++ b/release/src/router/busybox/mailutils/sendmail.c @@ -0,0 +1,259 @@ +/* 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) +{ + char *opt_connect = opt_connect; + char *opt_from; + char *s; + llist_t *list = NULL; + char *domain = sane_address(safe_getdomainname()); + int code; + + enum { + //--- standard options + OPT_t = 1 << 0, // read message for recipients, append them to those on cmdline + OPT_f = 1 << 1, // sender address + OPT_o = 1 << 2, // various options. -oi IMPLIED! others are IGNORED! + //--- BB specific options + OPT_w = 1 << 3, // network timeout + OPT_H = 1 << 4, // use external connection helper + OPT_S = 1 << 5, // specify connection string + OPT_a = 1 << 6, // authentication tokens + }; + + // init global variables + INIT_G(); + + // save initial stdin since body is piped! + xdup2(STDIN_FILENO, 3); + G.fp0 = fdopen(3, "r"); + + // parse options + // -f is required. -H and -S are mutually exclusive + opt_complementary = "f:w+:H--S:S--H:a::"; + // N.B. since -H and -S are mutually exclusive they do not interfere in opt_connect + // -a is for ssmtp (http://downloads.openwrt.org/people/nico/man/man8/ssmtp.8.html) compatibility, + // it is still under development. + opts = getopt32(argv, "tf:o:w:H:S:a::", &opt_from, NULL, &timeout, &opt_connect, &opt_connect, &list); + //argc -= optind; + argv += optind; + + // process -a[upm]<token> options + if ((opts & OPT_a) && !list) + bb_show_usage(); + while (list) { + char *a = (char *) llist_pop(&list); + if ('u' == a[0]) + G.user = xstrdup(a+1); + if ('p' == a[0]) + G.pass = xstrdup(a+1); + // N.B. we support only AUTH LOGIN so far + //if ('m' == a[0]) + // G.method = xstrdup(a+1); + } + // N.B. list == NULL here + //bb_info_msg("OPT[%x] AU[%s], AP[%s], AM[%s], ARGV[%s]", opts, au, ap, am, *argv); + + // connect to server + + // connection helper ordered? -> + if (opts & OPT_H) { + const char *args[] = { "sh", "-c", opt_connect, NULL }; + // plug it in + launch_helper(args); + // vanilla connection + } else { + 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 kick 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); + } + if (ENABLE_FEATURE_CLEAN_UP) + free(domain); + + // perform authentication + if (opts & OPT_a) { + smtp_check("AUTH LOGIN", 334); + // we must read credentials unless they are given via -a[up] options + if (!G.user || !G.pass) + get_cred_or_die(4); + encode_base64(NULL, G.user, NULL); + smtp_check("", 334); + encode_base64(NULL, G.pass, NULL); + smtp_check("", 235); + } + + // 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 + // N.B. we marked -f as required option! + //if (!G.user) { + // // N.B. IMHO getenv("USER") can be way easily spoofed! + // G.user = xuid2uname(getuid()); + // opt_from = xasprintf("%s@%s", G.user, domain); + //} + //if (ENABLE_FEATURE_CLEAN_UP) + // free(domain); + smtp_checkp("MAIL FROM:<%s>", opt_from, 250); + + // process message + + // read recipients from message and add them to those given on cmdline. + // this means we scan stdin for To:, Cc:, Bcc: lines until an empty line + // and then use the rest of stdin as message body + code = 0; // set "analyze headers" mode + while ((s = xmalloc_fgetline(G.fp0)) != NULL) { + // put message lines doubling leading dots + if (code) { + // 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); + free(s); + continue; + } + + // analyze headers + // To: or Cc: headers add recipients + if (0 == strncasecmp("To: ", s, 4) || 0 == strncasecmp("Bcc: " + 1, s, 4)) { + rcptto(sane_address(s+4)); +// goto addh; + llist_add_to_end(&list, s); + // Bcc: header adds blind copy (hidden) recipient + } else if (0 == strncasecmp("Bcc: ", s, 5)) { + rcptto(sane_address(s+5)); + free(s); + // N.B. Bcc: vanishes from headers! + // other headers go verbatim + } else if (s[0]) { +// addh: + llist_add_to_end(&list, s); + // the empty line stops analyzing headers + } else { + free(s); + // put recipients specified on cmdline + while (*argv) { + s = sane_address(*argv); + rcptto(s); + llist_add_to_end(&list, xasprintf("To: %s", s)); + argv++; + } + // enter "put message" mode + smtp_check("DATA", 354); + // dump the headers + while (list) { + printf("%s\r\n", (char *) llist_pop(&list)); + } + printf("%s\r\n" + 2); // quirk for format string to be reused + // stop analyzing headers + code++; + } + } + + // finalize the message + smtp_check(".", 250); + // ... and say goodbye + smtp_check("QUIT", 221); + // cleanup + if (ENABLE_FEATURE_CLEAN_UP) + fclose(G.fp0); + + return EXIT_SUCCESS; +} |