mirror of
https://github.com/sheumann/hush.git
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Signed-off-by: Vladimir Dronnikov <dronnikov@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
261 lines
7.5 KiB
C
261 lines
7.5 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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#include "mail.h"
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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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if (timeout)
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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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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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// strip argument of bad chars
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static char *sane_address(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 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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char *opt_connect = opt_connect;
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char *opt_from;
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char *s;
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llist_t *list = NULL;
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char *domain = sane_address(safe_getdomainname());
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int code;
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enum {
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//--- standard options
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OPT_t = 1 << 0, // read message for recipients, append them to those on cmdline
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OPT_f = 1 << 1, // sender address
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OPT_o = 1 << 2, // various options. -oi IMPLIED! others are IGNORED!
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OPT_i = 1 << 3, // IMPLIED!
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//--- BB specific options
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OPT_w = 1 << 4, // network timeout
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OPT_H = 1 << 5, // use external connection helper
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OPT_S = 1 << 6, // specify connection string
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OPT_a = 1 << 7, // authentication tokens
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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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G.fp0 = fdopen(3, "r");
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// parse options
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// -f is required. -H and -S are mutually exclusive
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opt_complementary = "f:w+:H--S:S--H:a::";
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// N.B. since -H and -S are mutually exclusive they do not interfere in opt_connect
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// -a is for ssmtp (http://downloads.openwrt.org/people/nico/man/man8/ssmtp.8.html) compatibility,
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// it is still under development.
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opts = getopt32(argv, "tf:o:iw:H:S:a::", &opt_from, NULL, &timeout, &opt_connect, &opt_connect, &list);
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//argc -= optind;
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argv += optind;
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// process -a[upm]<token> options
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if ((opts & OPT_a) && !list)
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bb_show_usage();
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while (list) {
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char *a = (char *) llist_pop(&list);
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if ('u' == a[0])
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G.user = xstrdup(a+1);
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if ('p' == a[0])
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G.pass = xstrdup(a+1);
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// N.B. we support only AUTH LOGIN so far
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//if ('m' == a[0])
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// G.method = xstrdup(a+1);
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}
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// N.B. list == NULL here
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//bb_info_msg("OPT[%x] AU[%s], AP[%s], AM[%s], ARGV[%s]", opts, au, ap, am, *argv);
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// connect to server
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// connection helper ordered? ->
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if (opts & OPT_H) {
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const char *args[] = { "sh", "-c", opt_connect, NULL };
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// plug it in
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launch_helper(args);
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// vanilla connection
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} else {
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int fd;
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// host[:port] not explicitly specified? -> use $SMTPHOST
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// no $SMTPHOST ? -> use localhost
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if (!(opts & OPT_S)) {
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opt_connect = getenv("SMTPHOST");
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if (!opt_connect)
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opt_connect = (char *)"127.0.0.1";
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}
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// do connect
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fd = create_and_connect_stream_or_die(opt_connect, 25);
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// and make ourselves a simple IO filter
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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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// N.B. from now we know nothing about network :)
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// wait for initial server OK
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// N.B. if we used openssl the initial 220 answer is already swallowed during openssl TLS init procedure
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// so we need to kick the server to see whether we are ok
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code = smtp_check("NOOP", -1);
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// 220 on plain connection, 250 on openssl-helped TLS session
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if (220 == code)
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smtp_check(NULL, 250); // reread the code to stay in sync
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else if (250 != code)
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bb_error_msg_and_die("INIT failed");
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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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// perform authentication
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if (opts & OPT_a) {
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smtp_check("AUTH LOGIN", 334);
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// we must read credentials unless they are given via -a[up] options
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if (!G.user || !G.pass)
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get_cred_or_die(4);
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encode_base64(NULL, G.user, NULL);
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smtp_check("", 334);
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encode_base64(NULL, G.pass, NULL);
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smtp_check("", 235);
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}
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// set sender
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// N.B. we have here a very loosely defined algotythm
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// since sendmail historically offers no means to specify secrets on cmdline.
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// 1) server can require no authentication ->
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// we must just provide a (possibly fake) reply address.
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// 2) server can require AUTH ->
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// we must provide valid username and password along with a (possibly fake) reply address.
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// For the sake of security username and password are to be read either from console or from a secured file.
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// Since reading from console may defeat usability, the solution is either to read from a predefined
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// file descriptor (e.g. 4), or again from a secured file.
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// got no sender address? -> use system username as a resort
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// N.B. we marked -f as required option!
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//if (!G.user) {
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// // N.B. IMHO getenv("USER") can be way easily spoofed!
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// G.user = xuid2uname(getuid());
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// opt_from = xasprintf("%s@%s", G.user, domain);
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//}
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//if (ENABLE_FEATURE_CLEAN_UP)
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// free(domain);
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smtp_checkp("MAIL FROM:<%s>", opt_from, 250);
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// process message
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// read recipients from message and add them to those given on cmdline.
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// this means we scan stdin for To:, Cc:, Bcc: lines until an empty line
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// and then use the rest of stdin as message body
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code = 0; // set "analyze headers" mode
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while ((s = xmalloc_fgetline(G.fp0)) != NULL) {
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// put message lines doubling leading dots
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if (code) {
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// escape leading dots
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// N.B. this feature is implied even if no -i (-oi) switch given
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// N.B. we need to escape the leading dot regardless of
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// whether it is single or not character on the line
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if ('.' == s[0] /*&& '\0' == s[1] */)
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printf(".");
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// dump read line
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printf("%s\r\n", s);
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free(s);
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continue;
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}
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// analyze headers
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// To: or Cc: headers add recipients
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if (0 == strncasecmp("To: ", s, 4) || 0 == strncasecmp("Bcc: " + 1, s, 4)) {
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rcptto(sane_address(s+4));
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// goto addh;
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llist_add_to_end(&list, s);
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// Bcc: header adds blind copy (hidden) recipient
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} else if (0 == strncasecmp("Bcc: ", s, 5)) {
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rcptto(sane_address(s+5));
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free(s);
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// N.B. Bcc: vanishes from headers!
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// other headers go verbatim
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} else if (s[0]) {
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// addh:
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llist_add_to_end(&list, s);
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// the empty line stops analyzing headers
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} else {
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free(s);
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// put recipients specified on cmdline
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while (*argv) {
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s = sane_address(*argv);
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rcptto(s);
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llist_add_to_end(&list, xasprintf("To: %s", s));
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argv++;
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}
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// enter "put message" mode
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smtp_check("DATA", 354);
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// dump the headers
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while (list) {
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printf("%s\r\n", (char *) llist_pop(&list));
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}
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printf("%s\r\n" + 2); // quirk for format string to be reused
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// stop analyzing headers
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code++;
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}
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}
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// finalize the message
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smtp_check(".", 250);
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// ... and say goodbye
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smtp_check("QUIT", 221);
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// cleanup
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if (ENABLE_FEATURE_CLEAN_UP)
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fclose(G.fp0);
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return EXIT_SUCCESS;
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}
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