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-rw-r--r--mailutils/sendmail.c388
1 files changed, 388 insertions, 0 deletions
diff --git a/mailutils/sendmail.c b/mailutils/sendmail.c
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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;
+}