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-rw-r--r--networking/sendmail.c313
1 files changed, 313 insertions, 0 deletions
diff --git a/networking/sendmail.c b/networking/sendmail.c
new file mode 100644
index 0000000..2ea10b1
--- /dev/null
+++ b/networking/sendmail.c
@@ -0,0 +1,313 @@
+/* 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"
+
+/*
+ Extracted from BB uuencode.c
+ */
+enum {
+ SRC_BUF_SIZE = 45, /* This *MUST* be a multiple of 3 */
+ DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3),
+};
+
+static void uuencode(const char *fname)
+{
+ int fd;
+ char src_buf[SRC_BUF_SIZE];
+ char dst_buf[1 + DST_BUF_SIZE + 1];
+
+ fd = xopen(fname, O_RDONLY);
+ fflush(stdout);
+ dst_buf[0] = '\n';
+ while (1) {
+ size_t size = full_read(fd, src_buf, SRC_BUF_SIZE);
+ if (!size)
+ break;
+ if ((ssize_t)size < 0)
+ bb_perror_msg_and_die(bb_msg_read_error);
+ /* Encode the buffer we just read in */
+ bb_uuencode(dst_buf + 1, src_buf, size, bb_uuenc_tbl_base64);
+ xwrite(STDOUT_FILENO, dst_buf, 1 + 4 * ((size + 2) / 3));
+ }
+ close(fd);
+}
+
+// "inline" version
+// encodes content of given buffer instead of fd
+// used to encode subject and authentication terms
+static void uuencode_inline(const char *src_buf)
+{
+ size_t len;
+ char dst_buf[DST_BUF_SIZE + 1];
+
+ len = strlen(src_buf);
+ fflush(stdout);
+ while (len > 0) {
+ size_t chunk = (len <= SRC_BUF_SIZE) ? len : SRC_BUF_SIZE;
+ bb_uuencode(dst_buf, src_buf, chunk, bb_uuenc_tbl_base64);
+ xwrite(STDOUT_FILENO, dst_buf, 4 * ((chunk + 2) / 3));
+ src_buf += chunk;
+ len -= chunk;
+ }
+}
+
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+// generic signal handler
+static void signal_handler(int signo)
+{
+ int err;
+
+ if (SIGALRM == signo)
+ bb_error_msg_and_die("timed out");
+
+ // SIGCHLD. reap zombies
+ if (wait_any_nohang(&err) > 0)
+ if (WIFEXITED(err) && WEXITSTATUS(err))
+ bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err));
+}
+
+static pid_t helper_pid = -1;
+
+// read stdin, parses first bytes to a number, i.e. server response
+// if code = -1 then just return this number
+// if code != -1 then checks whether the number equals the code
+// if not equal -> die saying errmsg
+static int check(int code, const char *errmsg)
+{
+ char *answer;
+
+ // read a string and match it against the set of available answers
+ fflush(stdout);
+ answer = xmalloc_getline(stdin);
+ if (answer) {
+ int n = atoi(answer);
+ if (-1 == code || n == code) {
+ free(answer);
+ return n;
+ }
+ }
+ // TODO!!!: is there more elegant way to terminate child on program failure?
+ if (helper_pid > 0)
+ kill(helper_pid, SIGTERM);
+ if (!answer)
+ answer = (char*)"EOF";
+ else
+ *strchrnul(answer, '\r') = '\0';
+ bb_error_msg_and_die("error at %s: got '%s' instead", errmsg, answer);
+}
+
+static int puts_and_check(const char *msg, int code, const char *errmsg)
+{
+ puts(msg);
+ return check(code, errmsg);
+}
+#endif
+
+int sendmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int sendmail_main(int argc, char **argv)
+{
+ llist_t *recipients = NULL;
+ llist_t *bodies = NULL;
+ llist_t *attachments = NULL;
+ const char *from;
+ const char *notify;
+ const char *subject;
+ const char *charset = "utf-8";
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+ const char *wsecs = "10";
+ const char *server = "127.0.0.1";
+ const char *port = NULL;
+ const char *opt_user;
+ const char *opt_pass;
+ unsigned timeout;
+#endif
+ char *boundary;
+ unsigned opts;
+ enum {
+ OPT_f = 1 << 0, // sender
+ OPT_n = 1 << 2, // notification
+ OPT_s = 1 << 3, // subject given
+ OPT_d = 1 << 7, // dry run - no networking
+ OPT_w = 1 << 8, // network timeout
+ OPT_h = 1 << 9, // server
+ OPT_p = 1 << 10, // port
+ OPT_U = 1 << 11, // user specified
+ OPT_P = 1 << 12, // password specified
+ };
+
+ // -f must be specified
+ // -t, -b, -a may be multiple
+ opt_complementary = "f:t::b::a::";
+ opts = getopt32(argv,
+ "f:t:n::s:b:a:c:" USE_FEATURE_SENDMAIL_NETWORK("dw:h:p:U:P:"),
+ &from, &recipients, &notify, &subject, &bodies, &attachments, &charset
+ USE_FEATURE_SENDMAIL_NETWORK(, &wsecs, &server, &port, &opt_user, &opt_pass)
+ );
+ //argc -= optind;
+ argv += optind;
+
+//printf("OPTS[%4x]\n", opts);
+
+ // TODO!!!: strip recipients and sender from <>
+
+ // establish connection
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+ timeout = xatou(wsecs);
+ if (!(opts & OPT_d)) {
+ // ask password if we need to and while we're still have terminal
+ // TODO: get password directly from /dev/tty? or from a secret file?
+ if ((opts & (OPT_U+OPT_P)) == OPT_U) {
+ if (!isatty(STDIN_FILENO) || !(opt_pass = bb_askpass(0, "Password: "))) {
+ bb_error_msg_and_die("no password");
+ }
+ }
+//printf("OPTS[%4x][%s][%s]\n", opts, opt_user, opt_pass);
+//exit(0);
+ // set chat timeout
+ alarm(timeout);
+ // connect to server
+ if (argv[0]) {
+ // if connection helper given
+ // setup vanilla unidirectional pipes interchange
+ int pipes[4];
+ xpipe(pipes);
+ xpipe(pipes+2);
+ helper_pid = vfork();
+ if (helper_pid < 0)
+ bb_perror_msg_and_die("vfork");
+ xdup2(pipes[(helper_pid)?0:2], STDIN_FILENO);
+ xdup2(pipes[(helper_pid)?3:1], STDOUT_FILENO);
+ if (ENABLE_FEATURE_CLEAN_UP)
+ for (int i = 4; --i >= 0; )
+ if (pipes[i] > STDOUT_FILENO)
+ close(pipes[i]);
+ // replace child with connection helper
+ if (!helper_pid) {
+ // child - try to execute connection helper
+ BB_EXECVP(argv[0], argv);
+ _exit(127);
+ }
+ // parent - check whether child is alive
+ sig_catch(SIGCHLD, signal_handler);
+ sig_catch(SIGALRM, signal_handler);
+ signal_handler(SIGCHLD);
+ // child seems OK -> parent goes on SMTP chat
+ } else {
+ // no connection helper provided -> make plain connect
+ int fd = create_and_connect_stream_or_die(
+ server,
+ bb_lookup_port(port, "tcp", 25)
+ );
+ xmove_fd(fd, STDIN_FILENO);
+ xdup2(STDIN_FILENO, STDOUT_FILENO);
+ // wait for OK
+ check(220, "INIT");
+ }
+ // mail user specified? try modern AUTHentication
+ if (opt_user && (334 == puts_and_check("auth login", -1, "auth login"))) {
+ uuencode_inline(opt_user);
+ puts_and_check("", 334, "AUTH");
+ uuencode_inline(opt_pass);
+ puts_and_check("", 235, "AUTH");
+ // no mail user specified or modern AUTHentication is not supported?
+ } else {
+ // fallback to simple HELO authentication
+ // fetch domain name (defaults to local)
+ const char *domain = strchr(from, '@');
+ if (domain)
+ domain++;
+ else
+ domain = "local";
+ printf("helo %s\n", domain);
+ check(250, "HELO");
+ }
+
+ // set addresses
+ printf("mail from:<%s>\n", from);
+ check(250, "MAIL FROM");
+ for (llist_t *to = recipients; to; to = to->link) {
+ printf("rcpt to:<%s>\n", to->data);
+ check(250, "RCPT TO");
+ }
+ puts_and_check("data", 354, "DATA");
+ // no timeout while sending message
+ alarm(0);
+ }
+#endif
+
+ // now put message
+ // put address headers
+ printf("From: %s\n", from);
+ for (llist_t *to = recipients; to; to = to->link) {
+ printf("To: %s\n", to->data);
+ }
+ // put encoded subject
+ if (opts & OPT_s) {
+ printf("Subject: =?%s?B?", charset);
+ uuencode_inline(subject);
+ puts("?=");
+ }
+ // put notification
+ if (opts & OPT_n) {
+ const char *s = notify;
+ if (!s[0])
+ s = from; // notify sender by default
+ printf("Disposition-Notification-To: %s\n", s);
+ }
+ // put common headers and body start
+ //srand(?);
+ boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
+ printf(
+ "X-Mailer: busybox " BB_VER " sendmail\n"
+ "X-Priority: 3\n"
+ "Message-ID: <%s>\n"
+ "Mime-Version: 1.0\n"
+ "Content-Type: multipart/mixed; boundary=\"%s\"\n"
+ "\n"
+ "--%s\n"
+ "Content-Type: text/plain; charset=%s\n"
+ "%s\n%s"
+ , boundary, boundary, boundary, charset
+ , "Content-Disposition: inline"
+ , "Content-Transfer-Encoding: base64\n"
+ );
+ // put body(ies)
+ for (llist_t *f = bodies; f; f = f->link) {
+ uuencode(f->data);
+ }
+ // put attachment(s)
+ for (llist_t *f = attachments; f; f = f->link) {
+ printf(
+ "\n--%s\n"
+ "Content-Type: application/octet-stream\n"
+ "%s; filename=\"%s\"\n"
+ "%s"
+ , boundary
+ , "Content-Disposition: inline"
+ , bb_get_last_path_component_strip(f->data)
+ , "Content-Transfer-Encoding: base64\n"
+ );
+ uuencode(f->data);
+ }
+ // put terminator
+ printf("\n--%s--\n\n", boundary);
+ if (ENABLE_FEATURE_CLEAN_UP)
+ free(boundary);
+
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+ // end message and say goodbye
+ if (!(opts & OPT_d)) {
+ alarm(timeout);
+ puts_and_check(".", 250, "BODY");
+ puts_and_check("quit", 221, "QUIT");
+ }
+#endif
+
+ return 0;
+}
generated by cgit v1.1 at 2024-11-16 20:52:21 +0000