hush/networking/sendmail.c
2008-02-17 14:28:53 +00:00

533 lines
12 KiB
C

/* vi: set sw=4 ts=4: */
/*
* bare bones sendmail/fetchmail
*
* Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
*
* Licensed under GPLv2, see file LICENSE in this tarball for details.
*/
#include "libbb.h"
#define INITIAL_STDIN_FILENO 3
static void uuencode(char *fname, const char *text)
{
enum {
SRC_BUF_SIZE = 45, /* This *MUST* be a multiple of 3 */
DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3),
};
#define src_buf text
int fd;
#define len fd
char dst_buf[DST_BUF_SIZE + 1];
if (fname) {
fd = INITIAL_STDIN_FILENO;
if (NOT_LONE_DASH(fname))
fd = xopen(fname, O_RDONLY);
src_buf = bb_common_bufsiz1;
} else {
len = strlen(text);
}
fflush(stdout); // sync stdio and unistd output
while (1) {
size_t size;
if (fname) {
size = full_read(fd, (char *)src_buf, SRC_BUF_SIZE);
if ((ssize_t)size < 0)
bb_perror_msg_and_die(bb_msg_read_error);
} else {
size = len;
if (len > SRC_BUF_SIZE)
size = SRC_BUF_SIZE;
}
if (!size)
break;
// encode the buffer we just read in
bb_uuencode(dst_buf, src_buf, size, bb_uuenc_tbl_base64);
if (fname) {
xwrite(STDOUT_FILENO, "\r\n", 2);
} else {
src_buf += size;
len -= size;
}
xwrite(STDOUT_FILENO, dst_buf, 4 * ((size + 2) / 3));
}
if (fname)
close(fd);
}
static pid_t helper_pid;
static void kill_helper(void)
{
// TODO!!!: is there more elegant way to terminate child on program failure?
if (helper_pid > 0)
kill(helper_pid, SIGTERM);
}
// generic signal handler
static void signal_handler(int signo)
{
int err;
if (SIGALRM == signo) {
kill_helper();
bb_error_msg_and_die("timed out");
}
// SIGCHLD. reap zombies
if (wait_any_nohang(&err) > 0)
if (WIFEXITED(err) && WEXITSTATUS(err))
#if ENABLE_FEATURE_SENDMAIL_BLOATY
bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err));
#else
bb_error_msg_and_die("child failed");
#endif
}
static void launch_helper(const char **argv)
{
// setup vanilla unidirectional pipes interchange
int idx;
int pipes[4];
xpipe(pipes);
xpipe(pipes+2);
helper_pid = vfork();
if (helper_pid < 0)
bb_perror_msg_and_die("vfork");
idx = (!helper_pid)*2;
xdup2(pipes[idx], STDIN_FILENO);
xdup2(pipes[3-idx], STDOUT_FILENO);
if (ENABLE_FEATURE_CLEAN_UP)
for (int i = 4; --i >= 0; )
if (pipes[i] > STDOUT_FILENO)
close(pipes[i]);
if (!helper_pid) {
// child - try to execute connection helper
BB_EXECVP(argv[0], (char **)argv);
_exit(127);
}
// parent - check whether child is alive
bb_signals_recursive(0
+ (1 << SIGCHLD)
+ (1 << SIGALRM)
, signal_handler);
signal_handler(SIGCHLD);
// child seems OK -> parent goes on
}
static unsigned timeout;
static char *command(const char *fmt, const char *param)
{
char *msg = (char *)fmt;
alarm(timeout);
if (msg) {
// if (param)
msg = xasprintf(fmt, param);
printf("%s\r\n", msg);
}
fflush(stdout);
return msg;
}
static int smtp_checkp(const char *fmt, const char *param, int code)
{
char *answer;
char *msg = command(fmt, param);
// read stdin
// if the string has a form \d\d\d- -- read next string. E.g. EHLO response
// parse first bytes to a number
// if code = -1 then just return this number
// if code != -1 then checks whether the number equals the code
// if not equal -> die saying msg
#if ENABLE_FEATURE_SENDMAIL_EHLO
while ((answer = xmalloc_getline(stdin)) && '-' == answer[3]) ;
#else
answer = xmalloc_getline(stdin);
#endif
if (answer) {
int n = atoi(answer);
alarm(0);
if (ENABLE_FEATURE_CLEAN_UP) {
free(msg);
free(answer);
}
if (-1 == code || n == code) {
return n;
}
}
kill_helper();
bb_error_msg_and_die("%s failed", msg);
}
static int smtp_check(const char *fmt, int code)
{
return smtp_checkp(fmt, NULL, code);
}
static void pop3_checkr(const char *fmt, const char *param, char **ret)
{
char *msg = command(fmt, param);
char *answer = xmalloc_getline(stdin);
if (answer && '+' == answer[0]) {
alarm(0);
if (ret)
*ret = answer;
else
free(answer);
return;
}
kill_helper();
bb_error_msg_and_die("%s failed", msg);
}
static void pop3_check(const char *fmt, const char *param)
{
pop3_checkr(fmt, param, NULL);
}
// strip argument of bad chars
static char *sane(char *str)
{
char *s = str;
char *p = s;
while (*s) {
if (isalnum(*s) || '_' == *s || '-' == *s || '.' == *s || '@' == *s) {
*p++ = *s;
}
s++;
}
*p = '\0';
return str;
}
static void pop3_message(int fd)
{
char *answer;
// read stdin, copy to file fd
while ((answer = xmalloc_fgets_str(stdin, "\r\n"))) {
char *s = answer;
if ('.' == answer[0]) {
if ('.' == answer[1])
s++;
else if ('\r' == answer[1] && '\n' == answer[2] && '\0' == answer[3])
break;
}
xwrite(fd, s, strlen(s));
free(answer);
}
close(fd);
}
static const char *args[] = {
"openssl", "s_client", "-quiet", "-connect", NULL, "-tls1", "-starttls", "smtp", NULL
};
#define opt_connect args[4]
#define opt_after_connect args[5]
int sendgetmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sendgetmail_main(int argc, char **argv)
{
llist_t *recipients = NULL;
char *from;
const char *subject;
char *charset = (char *)"utf-8";
const char *opt_user;
const char *opt_pass;
const char *opt_timeout;
const char *opt_chdir;
enum {
OPT_C = 1 << 0, // chdir
OPT_w = 1 << 1, // network timeout
OPT_U = 1 << 2, // user
OPT_P = 1 << 3, // password
OPT_X = 1 << 4, // use openssl connection helper
OPTS_t = 1 << 5, // sendmail "to"
OPTF_t = 1 << 5, // fetchmail "TOP"
OPTS_f = 1 << 6, // sendmail "from"
OPTF_z = 1 << 6, // fetchmail "delete"
OPTS_n = 1 << 7, // notification
OPTS_s = 1 << 8, // subject given
OPTS_c = 1 << 9, // charset for subject and body
};
const char *options;
unsigned opts;
// SENDMAIL
if ('s' == applet_name[0]) {
// save initial stdin
xdup2(STDIN_FILENO, INITIAL_STDIN_FILENO);
// -f must be specified
// -t may be multiple
opt_complementary = "-1:f:t::";
options = "C:w:U:P:X" "t:f:ns:c:";
// FETCHMAIL
} else {
opt_after_connect = NULL;
opt_complementary = "=1:P";
options = "C:w:U:P:X" "tz";
}
opts = getopt32(argv, options,
&opt_chdir, &opt_timeout, &opt_user, &opt_pass,
&recipients, &from, &subject, &charset
);
//argc -= optind;
argv += optind;
// first argument is remote server[:port]
opt_connect = *argv++;
if (opts & OPT_w)
timeout = xatou(opt_timeout);
// chdir
if (opts & OPT_C)
xchdir(opt_chdir);
// connect to server
if (opts & OPT_X) {
launch_helper(args);
} else {
// no connection helper provided -> make plain connect
int fd = create_and_connect_stream_or_die(opt_connect, 0);
xmove_fd(fd, STDIN_FILENO);
xdup2(STDIN_FILENO, STDOUT_FILENO);
}
// randomize
srand(time(NULL));
// SENDMAIL
if (recipients) {
int code;
char *boundary;
// wait for initial OK on plain connect
if (!(opts & OPT_X))
smtp_check(NULL, 220);
sane(from);
// introduce to server
// should we respect modern (but useless here) EHLO?
// or should they respect we wanna be tiny?!
if (!ENABLE_FEATURE_SENDMAIL_EHLO || 250 != smtp_checkp("EHLO %s", from, -1)) {
smtp_checkp("HELO %s", from, 250);
}
// set sender
// NOTE: if password has not been specified ->
// no authentication is possible
code = (opts & OPT_P) ? -1 : 250;
// first try softly without authentication
while (250 != smtp_checkp("MAIL FROM:<%s>", from, code)) {
// MAIL FROM failed -> authentication needed
// do we have username?
if (!(opts & OPT_U)) {
// no! fetch it from "from" option
//opts |= OPT_U;
opt_user = xstrdup(from);
*strchrnul(opt_user, '@') = '\0';
}
// now it seems we have username
// try to authenticate
if (334 == smtp_check("AUTH LOGIN", -1)) {
uuencode(NULL, opt_user);
smtp_check("", 334);
uuencode(NULL, opt_pass);
smtp_check("", 235);
}
// authenticated -> retry set sender
// but now die on failure
code = 250;
}
// set recipients
for (llist_t *to = recipients; to; to = to->link) {
smtp_checkp("RCPT TO:<%s>", sane(to->data), 250);
}
// now put message
smtp_check("DATA", 354);
// put address headers
printf("From: %s\r\n", from);
for (llist_t *to = recipients; to; to = to->link) {
printf("To: %s\r\n", to->data);
}
// put encoded subject
if (opts & OPTS_c)
sane(charset);
if (opts & OPTS_s) {
printf("Subject: =?%s?B?", charset);
uuencode(NULL, subject);
printf("?=\r\n");
}
// put notification
if (opts & OPTS_n)
printf("Disposition-Notification-To: %s\r\n", from);
// put common headers and body start
boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
printf(
USE_FEATURE_SENDMAIL_BLOATY("X-Mailer: busybox " BB_VER " sendmail\r\n")
"Message-ID: <%s>\r\n"
"Mime-Version: 1.0\r\n"
"%smultipart/mixed; boundary=\"%s\"\r\n"
, boundary
, "Content-Type: "
, boundary
);
// put body + attachment(s)
{
const char *fmt =
"\r\n--%s\r\n"
"%stext/plain; charset=%s\r\n"
"%s%s\r\n"
"%s"
;
const char *p = charset;
char *q = (char *)"";
while (argv[0]) {
printf(
fmt
, boundary
, "Content-Type: "
, p
, "Content-Disposition: inline"
, q
, "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(*argv, NULL);
if (*(++argv))
q = bb_get_last_path_component_strip(argv[0]);
}
}
// put terminator
printf("\r\n--%s--\r\n" "\r\n", boundary);
if (ENABLE_FEATURE_CLEAN_UP)
free(boundary);
// end message and say goodbye
smtp_check(".", 250);
smtp_check("QUIT", 221);
// FETCHMAIL
} else {
// authenticate
char *buf;
unsigned nmsg;
if (!(opts & OPT_U)) {
//opts |= OPT_U;
opt_user = getenv("USER");
}
#if ENABLE_FEATURE_FETCHMAIL_APOP
pop3_checkr(NULL, NULL, &buf);
// server supports APOP?
if ('<' == buf[4]) {
md5_ctx_t md5;
uint8_t hex[16*2 + 1];
// yes. compose <stamp><password>
char *s = strchr(buf, '>');
if (s)
strcpy(s+1, opt_pass);
s = buf+4;
// get md5 sum of <stamp><password>
md5_begin(&md5);
md5_hash(s, strlen(s), &md5);
md5_end(s, &md5);
bin2hex(hex, s, 16);
// APOP
s = xasprintf("%s %s", opt_user, hex);
pop3_check("APOP %s", s);
if (ENABLE_FEATURE_CLEAN_UP) {
free(s);
free(buf);
}
} else {
#else
{
pop3_check(NULL, NULL);
#endif
// USER
pop3_check("USER %s", opt_user);
// PASS
pop3_check("PASS %s", opt_pass);
}
// get statistics
pop3_checkr("STAT", NULL, &buf);
// get number of messages
nmsg = atoi(buf+4);
if (ENABLE_FEATURE_CLEAN_UP)
free(buf);
// lock maildir
////USE_FEATURE_CLEAN_UP(close)(xopen(".lock", O_CREAT | O_WRONLY | O_TRUNC | O_EXCL));
// make tempnam(dir, salt) respect dir argument
unsetenv("TMPDIR");
// TODO: piping through external filter argv... if *argv
// cache fetch command
{
const char *retr = (opts & OPTF_t) ? "TOP %u 0" : "RETR %u";
// loop through messages
for (; nmsg; nmsg--) {
int fd;
char tmp_name[sizeof("tmp/XXXXXX")];
char new_name[sizeof("new/XXXXXX")];
// retrieve message in ./tmp
strcpy(tmp_name, "tmp/XXXXXX");
fd = mkstemp(tmp_name);
if (fd < 0)
bb_perror_msg_and_die("cannot create unique file");
pop3_check(retr, (const char *)nmsg);
pop3_message(fd); // NB: closes fd
// move file to ./new atomically
strncpy(new_name, "new", 3);
strcpy(new_name + 3, tmp_name + 3);
if (rename(tmp_name, new_name) < 0) {
// rats! such file exists! try to make unique name
strcpy(new_name + 3, "tmp/XXXXXX" + 3);
fd = mkstemp(new_name);
if (fd < 0)
bb_perror_msg_and_die("cannot create unique file");
close(fd);
xrename(tmp_name, new_name);
}
// delete message from server
if (opts & OPTF_z)
pop3_check("DELE %u", (const char*)nmsg);
}
}
// Bye
pop3_check("QUIT", NULL);
// unlock maildir
////unlink(".lock");
}
return 0;
}