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556 lines
14 KiB
C
556 lines
14 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* bare bones sendmail
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*
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* Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
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*
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* Licensed under GPLv2, see file LICENSE in this tarball for details.
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*/
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#include "libbb.h"
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struct globals {
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pid_t helper_pid;
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unsigned timeout;
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FILE *fp0; // initial stdin
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// arguments for SSL connection helper
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const char *xargs[9];
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};
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#define G (*ptr_to_globals)
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#define helper_pid (G.helper_pid)
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#define timeout (G.timeout )
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#define fp0 (G.fp0 )
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#define xargs (G.xargs )
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#define INIT_G() do { \
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SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
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xargs[0] = "openssl"; \
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xargs[1] = "s_client"; \
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xargs[2] = "-quiet"; \
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xargs[3] = "-connect"; \
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/*xargs[4] = "localhost";*/ \
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xargs[5] = "-tls1"; \
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xargs[6] = "-starttls"; \
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xargs[7] = "smtp"; \
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} while (0)
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#define opt_connect (xargs[4])
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static void uuencode(char *fname, const char *text)
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{
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enum {
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SRC_BUF_SIZE = 45, /* This *MUST* be a multiple of 3 */
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DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3),
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};
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#define src_buf text
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FILE *fp = fp;
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ssize_t len = len;
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char dst_buf[DST_BUF_SIZE + 1];
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if (fname) {
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fp = (NOT_LONE_DASH(fname)) ? xfopen_for_read(fname) : fp0;
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src_buf = bb_common_bufsiz1;
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// N.B. strlen(NULL) segfaults!
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} else if (text) {
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// though we do not call uuencode(NULL, NULL) explicitly
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// still we do not want to break things suddenly
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len = strlen(text);
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} else
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return;
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while (1) {
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size_t size;
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if (fname) {
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size = fread((char *)src_buf, 1, SRC_BUF_SIZE, fp);
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if ((ssize_t)size < 0)
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bb_perror_msg_and_die(bb_msg_read_error);
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} else {
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size = len;
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if (len > SRC_BUF_SIZE)
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size = SRC_BUF_SIZE;
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}
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if (!size)
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break;
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// encode the buffer we just read in
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bb_uuencode(dst_buf, src_buf, size, bb_uuenc_tbl_base64);
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if (fname) {
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printf("\r\n");
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} else {
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src_buf += size;
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len -= size;
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}
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fwrite(dst_buf, 1, 4 * ((size + 2) / 3), stdout);
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}
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if (fname)
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fclose(fp);
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#undef src_buf
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}
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#if ENABLE_FEATURE_SENDMAIL_SSL
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static void kill_helper(void)
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{
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// TODO!!!: is there more elegant way to terminate child on program failure?
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if (helper_pid > 0)
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kill(helper_pid, SIGTERM);
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}
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// generic signal handler
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static void signal_handler(int signo)
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{
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#define err signo
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if (SIGALRM == signo) {
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kill_helper();
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bb_error_msg_and_die("timed out");
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}
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// SIGCHLD. reap zombies
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if (wait_any_nohang(&err) > 0)
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if (WIFEXITED(err)) {
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// if (WEXITSTATUS(err))
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bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err));
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// else
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// kill(0, SIGCONT);
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}
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#undef err
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}
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static void launch_helper(const char **argv)
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{
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// setup vanilla unidirectional pipes interchange
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int idx;
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int pipes[4];
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xpipe(pipes);
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xpipe(pipes+2);
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helper_pid = vfork();
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if (helper_pid < 0)
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bb_perror_msg_and_die("vfork");
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idx = (!helper_pid) * 2;
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xdup2(pipes[idx], STDIN_FILENO);
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xdup2(pipes[3-idx], STDOUT_FILENO);
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if (ENABLE_FEATURE_CLEAN_UP)
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for (int i = 4; --i >= 0; )
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if (pipes[i] > STDOUT_FILENO)
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close(pipes[i]);
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if (!helper_pid) {
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// child: try to execute connection helper
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BB_EXECVP(*argv, (char **)argv);
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_exit(127);
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}
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// parent: check whether child is alive
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bb_signals(0
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+ (1 << SIGCHLD)
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+ (1 << SIGALRM)
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, signal_handler);
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signal_handler(SIGCHLD);
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// child seems OK -> parent goes on
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}
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#else
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#define kill_helper() ((void)0)
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#define launch_helper(x) bb_error_msg_and_die("no SSL support")
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#endif
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static const char *command(const char *fmt, const char *param)
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{
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const char *msg = fmt;
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alarm(timeout);
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if (msg) {
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msg = xasprintf(fmt, param);
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printf("%s\r\n", msg);
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}
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fflush(stdout);
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return msg;
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}
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static int smtp_checkp(const char *fmt, const char *param, int code)
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{
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char *answer;
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const char *msg = command(fmt, param);
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// read stdin
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// if the string has a form \d\d\d- -- read next string. E.g. EHLO response
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// parse first bytes to a number
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// if code = -1 then just return this number
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// if code != -1 then checks whether the number equals the code
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// if not equal -> die saying msg
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while ((answer = xmalloc_fgetline(stdin)) != NULL)
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if (strlen(answer) <= 3 || '-' != answer[3])
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break;
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if (answer) {
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int n = atoi(answer);
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alarm(0);
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free(answer);
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if (-1 == code || n == code)
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return n;
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}
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kill_helper();
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bb_error_msg_and_die("%s failed", msg);
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}
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static inline int smtp_check(const char *fmt, int code)
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{
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return smtp_checkp(fmt, NULL, code);
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}
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// strip argument of bad chars
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static char *sane(char *str)
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{
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char *s = str;
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char *p = s;
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while (*s) {
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if (isalnum(*s) || '_' == *s || '-' == *s || '.' == *s || '@' == *s) {
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*p++ = *s;
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}
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s++;
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}
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*p = '\0';
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return str;
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}
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// NB: parse_url can modify url[] (despite const), but only if '@' is there
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static const char *parse_url(const char *url, const char **user, const char **pass)
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{
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// parse [user[:pass]@]host
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// return host
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char *s = strchr(url, '@');
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*user = *pass = NULL;
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if (s) {
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*s++ = '\0';
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*user = url;
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url = s;
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s = strchr(*user, ':');
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if (s) {
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*s++ = '\0';
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*pass = s;
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}
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}
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return url;
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}
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static void rcptto(const char *s)
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{
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smtp_checkp("RCPT TO:<%s>", s, 250);
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}
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int sendmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int sendmail_main(int argc UNUSED_PARAM, char **argv)
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{
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#if ENABLE_FEATURE_SENDMAIL_MAILX
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llist_t *opt_attachments = NULL;
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const char *opt_subject;
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const char *opt_charset = CONFIG_FEATURE_SENDMAIL_CHARSET;
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#if ENABLE_FEATURE_SENDMAIL_MAILXX
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llist_t *opt_carboncopies = NULL;
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char *opt_errors_to;
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#endif
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#endif
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char *opt_from, *opt_fullname;
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const char *opt_user;
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const char *opt_pass;
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int code;
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char *boundary;
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llist_t *l;
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llist_t *headers = NULL;
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char *domain = sane(safe_getdomainname());
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unsigned opts;
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enum {
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OPT_w = 1 << 0, // network timeout
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OPT_H = 1 << 1, // [user:password@]server[:port]
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OPT_S = 1 << 2, // connect using openssl s_client helper
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OPT_t = 1 << 3, // read message for recipients
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OPT_N = 1 << 4, // request notification
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OPT_f = 1 << 5, // sender address
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OPT_F = 1 << 6, // sender name, overrides $NAME
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OPT_s = 1 << 7, // subject
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OPT_j = 1 << 8, // assumed charset
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OPT_a = 1 << 9, // attachment(s)
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OPT_c = 1 << 10, // carbon copy
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OPT_e = 1 << 11, // errors-to address
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};
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// init global variables
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INIT_G();
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// save initial stdin since body is piped!
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xdup2(STDIN_FILENO, 3);
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fp0 = fdopen(3, "r");
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// parse options
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opt_complementary = "w+:a::" USE_FEATURE_SENDMAIL_MAILXX("c::");
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opts = getopt32(argv,
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"w:H:St" "N:f:F:" USE_FEATURE_SENDMAIL_MAILX("s:j:a:") USE_FEATURE_SENDMAIL_MAILXX("c:e:")
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"X:V:vq:R:O:o:nmL:Iih:GC:B:b:A:" // postfix compat only, ignored
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// r:Q:p:M:Dd are candidates from another man page. TODO?
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"46E", // ssmtp introduces another quirks. TODO?: -a[upm] (user, pass, method) to be supported
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&timeout /* -w */, &opt_connect /* -H */,
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NULL, &opt_from, &opt_fullname,
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USE_FEATURE_SENDMAIL_MAILX(&opt_subject, &opt_charset, &opt_attachments,)
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USE_FEATURE_SENDMAIL_MAILXX(&opt_carboncopies, &opt_errors_to,)
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NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
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);
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//argc -= optind;
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argv += optind;
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// connect to server
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// host[:port] not specified ? -> use $SMTPHOST. no $SMTPHOST ? -> use localhost
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if (!(opts & OPT_H)) {
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opt_connect = getenv("SMTPHOST");
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if (!opt_connect)
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opt_connect = "127.0.0.1";
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}
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// fetch username and password, if any
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// NB: parse_url modifies opt_connect[] ONLY if '@' is there.
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// Thus "127.0.0.1" won't be modified, an is ok that it is RO.
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opt_connect = parse_url(opt_connect, &opt_user, &opt_pass);
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// username must be defined!
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if (!opt_user) {
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// N.B. IMHO getenv("USER") can be way easily spoofed!
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opt_user = bb_getpwuid(NULL, -1, getuid());
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}
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// SSL ordered? ->
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if (opts & OPT_S) {
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// ... use openssl helper
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launch_helper(xargs);
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// no SSL ordered? ->
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} else {
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// ... make plain connect
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int fd = create_and_connect_stream_or_die(opt_connect, 25);
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// make ourselves a simple IO filter
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// from now we know nothing about network :)
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xmove_fd(fd, STDIN_FILENO);
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xdup2(STDIN_FILENO, STDOUT_FILENO);
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}
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// got no sender address? -> use username as a resort
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if (!(opts & OPT_f)) {
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opt_from = xasprintf("%s@%s", opt_user, domain);
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}
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// introduce to server
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// we didn't use SSL helper? ->
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if (!(opts & OPT_S)) {
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// ... wait for initial server OK
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smtp_check(NULL, 220);
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}
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// we should start with modern EHLO
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if (250 != smtp_checkp("EHLO %s", domain, -1)) {
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smtp_checkp("HELO %s", domain, 250);
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}
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if (ENABLE_FEATURE_CLEAN_UP)
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free(domain);
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// set sender
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// NOTE: if password has not been specified
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// then no authentication is possible
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code = (opt_pass ? -1 : 250);
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// first try softly without authentication
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while (250 != smtp_checkp("MAIL FROM:<%s>", opt_from, code)) {
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// MAIL FROM failed -> authentication needed
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if (334 == smtp_check("AUTH LOGIN", -1)) {
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uuencode(NULL, opt_user); // opt_user != NULL
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smtp_check("", 334);
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uuencode(NULL, opt_pass);
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smtp_check("", 235);
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}
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// authenticated OK? -> retry to set sender
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// but this time die on failure!
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code = 250;
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}
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// recipients specified as arguments
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while (*argv) {
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char *s = sane(*argv);
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// loose test on email address validity
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if (strchr(s, '@')) {
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rcptto(s);
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llist_add_to_end(&headers, xasprintf("To: %s", s));
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}
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argv++;
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}
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#if ENABLE_FEATURE_SENDMAIL_MAILXX
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// carbon copies recipients specified as -c options
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for (l = opt_carboncopies; l; l = l->link) {
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char *s = sane(l->data);
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// loose test on email address validity
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if (strchr(s, '@')) {
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rcptto(s);
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// TODO: do we ever need to mangle the message?
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//llist_add_to_end(&headers, xasprintf("Cc: %s", s));
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}
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}
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#endif
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// if -t specified or no recipients specified -> read recipients from message
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// i.e. scan stdin for To:, Cc:, Bcc: lines ...
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// ... and then use the rest of stdin as message body
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// N.B. subject read from body can be further overrided with one specified on command line.
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// recipients are merged. Bcc: lines are deleted
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// N.B. other headers are collected and will be dumped verbatim
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if (opts & OPT_t || !headers) {
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// fetch recipients and (optionally) subject
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char *s;
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while ((s = xmalloc_fgetline(fp0)) != NULL) {
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if (0 == strncasecmp("To: ", s, 4) || 0 == strncasecmp("Cc: ", s, 4)) {
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rcptto(sane(s+4));
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llist_add_to_end(&headers, s);
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} else if (0 == strncasecmp("Bcc: ", s, 5)) {
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rcptto(sane(s+5));
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free(s);
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// N.B. Bcc vanishes from headers!
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} else if (0 == strncmp("Subject: ", s, 9)) {
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// we read subject -> use it verbatim unless it is specified
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// on command line
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if (!(opts & OPT_s))
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llist_add_to_end(&headers, s);
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else
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free(s);
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} else if (s[0]) {
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// misc header
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llist_add_to_end(&headers, s);
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} else {
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free(s);
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break; // stop on the first empty line
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}
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}
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}
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// enter "put message" mode
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smtp_check("DATA", 354);
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// put headers we could have preread with -t
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for (l = headers; l; l = l->link) {
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printf("%s\r\n", l->data);
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if (ENABLE_FEATURE_CLEAN_UP)
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free(l->data);
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}
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// put (possibly encoded) subject
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if (opts & OPT_j)
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sane((char *)opt_charset);
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if (opts & OPT_s) {
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printf("Subject: ");
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if (opts & OPT_j) {
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printf("=?%s?B?", opt_charset);
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uuencode(NULL, opt_subject);
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printf("?=");
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} else {
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printf("%s", opt_subject);
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}
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printf("\r\n");
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}
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// put sender name, $NAME is the default
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if (!(opts & OPT_F))
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opt_fullname = getenv("NAME");
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if (opt_fullname)
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printf("From: \"%s\" <%s>\r\n", opt_fullname, opt_from);
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// put notification
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if (opts & OPT_N)
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printf("Disposition-Notification-To: %s\r\n", opt_from);
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#if ENABLE_FEATURE_SENDMAIL_MAILXX
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// put errors recipient
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if (opts & OPT_e)
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printf("Errors-To: %s\r\n", opt_errors_to);
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#endif
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// make a random string -- it will delimit message parts
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srand(monotonic_us());
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boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
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// put common headers
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// TODO: do we really need this?
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// printf("Message-ID: <%s>\r\n", boundary);
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#if ENABLE_FEATURE_SENDMAIL_MAILX
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// have attachments? -> compose multipart MIME
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if (opt_attachments) {
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const char *fmt;
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const char *p;
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char *q;
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printf(
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"Mime-Version: 1.0\r\n"
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"%smultipart/mixed; boundary=\"%s\"\r\n"
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, "Content-Type: "
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, boundary
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);
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// body is pseudo attachment read from stdin in first turn
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llist_add_to(&opt_attachments, (char *)"-");
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// put body + attachment(s)
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// N.B. all these weird things just to be tiny
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// by reusing string patterns!
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fmt =
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"\r\n--%s\r\n"
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"%stext/plain; charset=%s\r\n"
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"%s%s\r\n"
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"%s"
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;
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p = opt_charset;
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q = (char *)"";
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l = opt_attachments;
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while (l) {
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printf(
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fmt
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, boundary
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, "Content-Type: "
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, p
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, "Content-Disposition: inline"
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, q
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, "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"
|
|
;
|
|
uuencode(l->data, NULL);
|
|
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(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(fp0);
|
|
|
|
return EXIT_SUCCESS;
|
|
}
|