sendmail: really svn add it

1 files changed, 313 insertions, 0 deletions

diff --git a/networking/sendmail.c b/networking/sendmail.c
new file mode 100644
index 000000000..2ea10b124
--- /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;
+}