534 lines
12 KiB
C
534 lines
12 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* bare bones sendmail/fetchmail
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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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#define INITIAL_STDIN_FILENO 3
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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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int fd;
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#define len fd
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char dst_buf[DST_BUF_SIZE + 1];
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if (fname) {
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fd = INITIAL_STDIN_FILENO;
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if (NOT_LONE_DASH(fname))
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fd = xopen(fname, O_RDONLY);
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src_buf = bb_common_bufsiz1;
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} else {
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len = strlen(text);
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}
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fflush(stdout); // sync stdio and unistd output
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while (1) {
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size_t size;
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if (fname) {
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size = full_read(fd, (char *)src_buf, SRC_BUF_SIZE);
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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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xwrite(STDOUT_FILENO, "\r\n", 2);
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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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xwrite(STDOUT_FILENO, dst_buf, 4 * ((size + 2) / 3));
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}
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if (fname)
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close(fd);
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}
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static pid_t helper_pid;
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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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int err;
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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) && WEXITSTATUS(err))
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#if ENABLE_FEATURE_SENDMAIL_BLOATY
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bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err));
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#else
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bb_error_msg_and_die("child failed");
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#endif
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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[0], (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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sig_catch(SIGCHLD, signal_handler);
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sig_catch(SIGALRM, 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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static unsigned timeout;
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static char *command(const char *fmt, const char *param)
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{
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char *msg = (char *)fmt;
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alarm(timeout);
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if (msg) {
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// if (param)
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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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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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#if ENABLE_FEATURE_SENDMAIL_EHLO
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while ((answer = xmalloc_getline(stdin)) && '-' == answer[3]) ;
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#else
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answer = xmalloc_getline(stdin);
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#endif
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if (answer) {
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int n = atoi(answer);
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alarm(0);
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if (ENABLE_FEATURE_CLEAN_UP) {
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free(msg);
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free(answer);
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}
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if (-1 == code || n == code) {
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return n;
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}
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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 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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static void pop3_checkr(const char *fmt, const char *param, char **ret)
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{
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char *msg = command(fmt, param);
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char *answer = xmalloc_getline(stdin);
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if (answer && '+' == answer[0]) {
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alarm(0);
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if (ret)
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*ret = answer;
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else
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free(answer);
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return;
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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 void pop3_check(const char *fmt, const char *param)
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{
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pop3_checkr(fmt, param, NULL);
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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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static void pop3_message(int fd)
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{
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char *answer;
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// read stdin, copy to file fd
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while ((answer = xmalloc_fgets_str(stdin, "\r\n"))) {
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char *s = answer;
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if ('.' == answer[0]) {
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if ('.' == answer[1])
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s++;
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else if ('\r' == answer[1] && '\n' == answer[2] && '\0' == answer[3])
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break;
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}
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xwrite(fd, s, strlen(s));
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free(answer);
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}
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close(fd);
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}
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static const char *args[] = {
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"openssl", "s_client", "-quiet", "-connect", NULL, "-tls1", "-starttls", "smtp", NULL
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};
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#define opt_connect args[4]
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#define opt_after_connect args[5]
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int sendgetmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int sendgetmail_main(int argc, char **argv)
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{
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llist_t *recipients = NULL;
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char *from;
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const char *subject;
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char *charset = (char *)"utf-8";
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const char *opt_user;
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const char *opt_pass;
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const char *opt_timeout;
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const char *opt_chdir;
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enum {
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OPT_C = 1 << 0, // chdir
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OPT_w = 1 << 1, // network timeout
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OPT_U = 1 << 2, // user
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OPT_P = 1 << 3, // password
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OPT_X = 1 << 4, // use openssl connection helper
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OPTS_t = 1 << 5, // sendmail "to"
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OPTF_t = 1 << 5, // fetchmail "TOP"
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OPTS_f = 1 << 6, // sendmail "from"
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OPTF_z = 1 << 6, // fetchmail "delete"
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OPTS_n = 1 << 7, // notification
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OPTS_s = 1 << 8, // subject given
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OPTS_c = 1 << 9, // charset for subject and body
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};
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const char *options;
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unsigned opts;
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// SENDMAIL
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if ('s' == applet_name[0]) {
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// save initial stdin
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xdup2(STDIN_FILENO, INITIAL_STDIN_FILENO);
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// -f must be specified
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// -t may be multiple
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opt_complementary = "-1:f:t::";
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options = "C:w:U:P:X" "t:f:ns:c:";
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// FETCHMAIL
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} else {
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opt_after_connect = NULL;
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opt_complementary = "=1:P";
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options = "C:w:U:P:X" "tz";
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}
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opts = getopt32(argv, options,
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&opt_chdir, &opt_timeout, &opt_user, &opt_pass,
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&recipients, &from, &subject, &charset
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);
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//argc -= optind;
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argv += optind;
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// first argument is remote server[:port]
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opt_connect = *argv++;
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if (opts & OPT_w)
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timeout = xatou(opt_timeout);
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// chdir
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if (opts & OPT_C)
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xchdir(opt_chdir);
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// connect to server
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if (opts & OPT_X) {
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launch_helper(args);
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} else {
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// no connection helper provided -> make plain connect
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int fd = create_and_connect_stream_or_die(opt_connect, 0);
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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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// randomize
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srand(time(NULL));
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// SENDMAIL
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if (recipients) {
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int code;
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char *boundary;
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// wait for initial OK on plain connect
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if (!(opts & OPT_X))
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smtp_check(NULL, 220);
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sane(from);
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// introduce to server
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// should we respect modern (but useless here) EHLO?
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// or should they respect we wanna be tiny?!
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if (!ENABLE_FEATURE_SENDMAIL_EHLO || 250 != smtp_checkp("EHLO %s", from, -1)) {
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smtp_checkp("HELO %s", from, 250);
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}
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// set sender
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// NOTE: if password has not been specified ->
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// no authentication is possible
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code = (opts & OPT_P) ? -1 : 250;
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// first try softly without authentication
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while (250 != smtp_checkp("MAIL FROM:<%s>", from, code)) {
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// MAIL FROM failed -> authentication needed
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// do we have username?
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if (!(opts & OPT_U)) {
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// no! fetch it from "from" option
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//opts |= OPT_U;
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opt_user = xstrdup(from);
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*strchrnul(opt_user, '@') = '\0';
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}
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// now it seems we have username
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// try to authenticate
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if (334 == smtp_check("AUTH LOGIN", -1)) {
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uuencode(NULL, opt_user);
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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 -> retry set sender
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// but now die on failure
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code = 250;
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}
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// set recipients
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for (llist_t *to = recipients; to; to = to->link) {
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smtp_checkp("RCPT TO:<%s>", sane(to->data), 250);
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}
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// now put message
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smtp_check("DATA", 354);
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// put address headers
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printf("From: %s\r\n", from);
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for (llist_t *to = recipients; to; to = to->link) {
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printf("To: %s\r\n", to->data);
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}
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// put encoded subject
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if (opts & OPTS_c)
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sane(charset);
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if (opts & OPTS_s) {
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printf("Subject: =?%s?B?", charset);
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uuencode(NULL, subject);
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printf("?=\r\n");
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}
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// put notification
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if (opts & OPTS_n)
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printf("Disposition-Notification-To: %s\r\n", from);
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// put common headers and body start
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boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
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printf(
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USE_FEATURE_SENDMAIL_BLOATY("X-Mailer: busybox " BB_VER " sendmail\r\n")
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"Message-ID: <%s>\r\n"
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"Mime-Version: 1.0\r\n"
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"%smultipart/mixed; boundary=\"%s\"\r\n"
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, boundary
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, "Content-Type: "
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, boundary
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);
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// put body + attachment(s)
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{
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const char *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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const char *p = charset;
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char *q = (char *)"";
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while (argv[0]) {
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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"
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);
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p = "";
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fmt =
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"\r\n--%s\r\n"
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"%sapplication/octet-stream%s\r\n"
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"%s; filename=\"%s\"\r\n"
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"%s"
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;
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uuencode(*argv, NULL);
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if (*(++argv))
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q = bb_get_last_path_component_strip(argv[0]);
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}
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}
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// put terminator
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printf("\r\n--%s--\r\n" "\r\n", boundary);
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if (ENABLE_FEATURE_CLEAN_UP)
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free(boundary);
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// end message and say goodbye
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smtp_check(".", 250);
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smtp_check("QUIT", 221);
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// FETCHMAIL
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} else {
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// authenticate
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char *buf;
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unsigned nmsg;
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if (!(opts & OPT_U)) {
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//opts |= OPT_U;
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opt_user = getenv("USER");
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}
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#if ENABLE_FEATURE_FETCHMAIL_APOP
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pop3_checkr(NULL, NULL, &buf);
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// server supports APOP?
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if ('<' == buf[4]) {
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md5_ctx_t md5;
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uint8_t hex[16*2 + 1];
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// yes. compose <stamp><password>
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char *s = strchr(buf, '>');
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if (s)
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strcpy(s+1, opt_pass);
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s = buf+4;
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// get md5 sum of <stamp><password>
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md5_begin(&md5);
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md5_hash(s, strlen(s), &md5);
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md5_end(s, &md5);
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bin2hex(hex, s, 16);
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// APOP
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s = xasprintf("%s %s", opt_user, hex);
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pop3_check("APOP %s", s);
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if (ENABLE_FEATURE_CLEAN_UP) {
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free(s);
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free(buf);
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}
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} else {
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#else
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{
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pop3_check(NULL, NULL);
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#endif
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// USER
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pop3_check("USER %s", opt_user);
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// PASS
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pop3_check("PASS %s", opt_pass);
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}
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// get statistics
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pop3_checkr("STAT", NULL, &buf);
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// get number of messages
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nmsg = atoi(buf+4);
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if (ENABLE_FEATURE_CLEAN_UP)
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free(buf);
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// lock maildir
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////USE_FEATURE_CLEAN_UP(close)(xopen(".lock", O_CREAT | O_WRONLY | O_TRUNC | O_EXCL));
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// make tempnam(dir, salt) respect dir argument
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unsetenv("TMPDIR");
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// TODO: piping through external filter argv... if *argv
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// cache fetch command
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{
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const char *retr = (opts & OPTF_t) ? "TOP %u 0" : "RETR %u";
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// loop through messages
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for (; nmsg; nmsg--) {
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int fd;
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char tmp_name[sizeof("tmp/XXXXXX")];
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char new_name[sizeof("new/XXXXXX")];
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// retrieve message in ./tmp
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strcpy(tmp_name, "tmp/XXXXXX");
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fd = mkstemp(tmp_name);
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if (fd < 0)
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bb_perror_msg_and_die("cannot create unique file");
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pop3_check(retr, (const char *)nmsg);
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pop3_message(fd); // NB: closes fd
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// move file to ./new atomically
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strncpy(new_name, "new", 3);
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strcpy(new_name + 3, tmp_name + 3);
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if (rename(tmp_name, new_name) < 0) {
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// rats! such file exists! try to make unique name
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strcpy(new_name + 3, "tmp/XXXXXX" + 3);
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fd = mkstemp(new_name);
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if (fd < 0)
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bb_perror_msg_and_die("cannot create unique file");
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close(fd);
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if (rename(tmp_name, new_name) < 0) {
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// something is very wrong
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bb_perror_msg_and_die("cannot move %s to %s", tmp_name, new_name);
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}
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}
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// delete message from server
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if (opts & OPTF_z)
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pop3_check("DELE %u", (const char*)nmsg);
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}
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}
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// Bye
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pop3_check("QUIT", NULL);
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// unlock maildir
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////unlink(".lock");
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}
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return 0;
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}
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