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sendmail: don't talk until 220 code is seen. Closes 3487

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function                                             old     new   delta
sendmail_main                                        934     939      +5
smtp_checkp                                          167     165      -2
packed_usage                                       28634   28621     -13

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2011-09-18 03:01:49 +02:00
parent 0851d125c3
commit 34c469ae04
2 changed files with 58 additions and 43 deletions
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11
mailutils/mail.c
View File

@ -57,10 +57,13 @@ void FAST_FUNC launch_helper(const char **argv)
G.helper_pid = xvfork(); G.helper_pid = xvfork();
i = (!G.helper_pid) * 2; // for parent:0, for child:2 i = (!G.helper_pid) * 2; // for parent:0, for child:2
close(pipes[i + 1]); // 1 or 3 - closing one write end close(pipes[i + 1]); // 1 or 3 - closing one write end
close(pipes[2 - i]); // 2 or 0 - closing one read end close(pipes[2 - i]); // 2 or 0 - closing one read end
xmove_fd(pipes[i], STDIN_FILENO); // 0 or 2 - using other read end xmove_fd(pipes[i], STDIN_FILENO); // 0 or 2 - using other read end
xmove_fd(pipes[3 - i], STDOUT_FILENO); // 3 or 1 - other write end xmove_fd(pipes[3 - i], STDOUT_FILENO); // 3 or 1 - using other write end
// End result:
// parent stdout [3] -> child stdin [2]
// child stdout [1] -> parent stdin [0]
if (!G.helper_pid) { if (!G.helper_pid) {
// child: try to execute connection helper // child: try to execute connection helper

90
mailutils/sendmail.c
View File

@ -26,18 +26,18 @@
//usage: "\n Examples:" //usage: "\n Examples:"
//usage: "\n -H 'exec openssl s_client -quiet -tls1 -starttls smtp" //usage: "\n -H 'exec openssl s_client -quiet -tls1 -starttls smtp"
//usage: "\n -connect smtp.gmail.com:25' <email.txt" //usage: "\n -connect smtp.gmail.com:25' <email.txt"
//usage: "\n [4<username_and_passwd.txt | -au<username> -ap<password>]" //usage: "\n [4<username_and_passwd.txt | -auUSER -apPASS]"
//usage: "\n -H 'exec openssl s_client -quiet -tls1" //usage: "\n -H 'exec openssl s_client -quiet -tls1"
//usage: "\n -connect smtp.gmail.com:465' <email.txt" //usage: "\n -connect smtp.gmail.com:465' <email.txt"
//usage: "\n [4<username_and_passwd.txt | -au<username> -ap<password>]" //usage: "\n [4<username_and_passwd.txt | -auUSER -apPASS]"
//usage: "\n -S HOST[:PORT] Server" //usage: "\n -S HOST[:PORT] Server"
//usage: "\n -au<username> Username for AUTH LOGIN" //usage: "\n -auUSER Username for AUTH LOGIN"
//usage: "\n -ap<password> Password for AUTH LOGIN" //usage: "\n -apPASS Password for AUTH LOGIN"
//usage: "\n -am<method> Authentication method. Ignored. LOGIN is implied" ////usage: "\n -amMETHOD Authentication method. Ignored. LOGIN is implied"
//usage: "\n" //usage: "\n"
//usage: "\nOther options are silently ignored; -oi -t is implied" //usage: "\nOther options are silently ignored; -oi -t is implied"
//usage: IF_MAKEMIME( //usage: IF_MAKEMIME(
//usage: "\nUse makemime applet to create message with attachments" //usage: "\nUse makemime to create emails with attachments"
//usage: ) //usage: )
#include "libbb.h" #include "libbb.h"
@ -66,7 +66,7 @@ static int smtp_checkp(const char *fmt, const char *param, int code)
// if not equal -> die saying msg // if not equal -> die saying msg
while ((answer = xmalloc_fgetline(stdin)) != NULL) { while ((answer = xmalloc_fgetline(stdin)) != NULL) {
if (verbose) if (verbose)
bb_error_msg("recv:'%.*s' %d", (int)(strchrnul(answer, '\r') - answer), answer, verbose); bb_error_msg("recv:'%.*s'", (int)(strchrnul(answer, '\r') - answer), answer);
if (strlen(answer) <= 3 || '-' != answer[3]) if (strlen(answer) <= 3 || '-' != answer[3])
break; break;
free(answer); free(answer);
@ -75,10 +75,11 @@ static int smtp_checkp(const char *fmt, const char *param, int code)
int n = atoi(answer); int n = atoi(answer);
if (timeout) if (timeout)
alarm(0); alarm(0);
free(msg);
free(answer); free(answer);
if (-1 == code || n == code) if (-1 == code || n == code) {
free(msg);
return n; return n;
}
} }
bb_error_msg_and_die("%s failed", msg); bb_error_msg_and_die("%s failed", msg);
} }
@ -176,11 +177,35 @@ int sendmail_main(int argc UNUSED_PARAM, char **argv)
const char *args[] = { "sh", "-c", opt_connect, NULL }; const char *args[] = { "sh", "-c", opt_connect, NULL };
// plug it in // plug it in
launch_helper(args); launch_helper(args);
// vanilla connection // Now:
// our stdout will go to helper's stdin,
// helper's stdout will be available on our stdin.
// Wait for initial server message.
// If helper (such as openssl) invokes STARTTLS, the initial 220
// is swallowed by helper (and not repeated after TLS is initiated).
// We will send NOOP cmd to server and check the response.
// We should get 220+250 on plain connection, 250 on STARTTLSed session.
//
// The problem here is some servers delay initial 220 message,
// and consider client to be a spammer if it starts sending cmds
// before 220 reached it. The code below is unsafe in this regard:
// in non-STARTTLSed case, we potentially send NOOP before 220
// is sent by server.
// Ideas? (--delay SECS opt? --assume-starttls-helper opt?)
code = smtp_check("NOOP", -1);
if (code == 220)
// we got 220 - this is not STARTTLSed connection,
// eat 250 response to our NOOP
smtp_check(NULL, 250);
else
if (code != 250)
bb_error_msg_and_die("SMTP init failed");
} else { } else {
// vanilla connection
int fd; int fd;
// host[:port] not explicitly specified? -> use $SMTPHOST // host[:port] not explicitly specified? -> use $SMTPHOST
// no $SMTPHOST ? -> use localhost // no $SMTPHOST? -> use localhost
if (!(opts & OPT_S)) { if (!(opts & OPT_S)) {
opt_connect = getenv("SMTPHOST"); opt_connect = getenv("SMTPHOST");
if (!opt_connect) if (!opt_connect)
@ -191,25 +216,14 @@ int sendmail_main(int argc UNUSED_PARAM, char **argv)
// and make ourselves a simple IO filter // and make ourselves a simple IO filter
xmove_fd(fd, STDIN_FILENO); xmove_fd(fd, STDIN_FILENO);
xdup2(STDIN_FILENO, STDOUT_FILENO); xdup2(STDIN_FILENO, STDOUT_FILENO);
}
// N.B. from now we know nothing about network :)
// wait for initial server OK // Wait for initial server 220 message
// N.B. if we used openssl the initial 220 answer is already swallowed during openssl TLS init procedure smtp_check(NULL, 220);
// so we need to kick the server to see whether we are ok }
code = smtp_check("NOOP", -1);
// 220 on plain connection, 250 on openssl-helped TLS session
if (220 == code)
smtp_check(NULL, 250); // reread the code to stay in sync
else if (250 != code)
bb_error_msg_and_die("INIT failed");
// we should start with modern EHLO // we should start with modern EHLO
if (250 != smtp_checkp("EHLO %s", domain, -1)) { if (250 != smtp_checkp("EHLO %s", domain, -1))
smtp_checkp("HELO %s", domain, 250); smtp_checkp("HELO %s", domain, 250);
}
if (ENABLE_FEATURE_CLEAN_UP)
free(domain);
// perform authentication // perform authentication
if (opts & OPT_a) { if (opts & OPT_a) {
@ -224,7 +238,7 @@ int sendmail_main(int argc UNUSED_PARAM, char **argv)
} }
// set sender // set sender
// N.B. we have here a very loosely defined algotythm // N.B. we have here a very loosely defined algorythm
// since sendmail historically offers no means to specify secrets on cmdline. // since sendmail historically offers no means to specify secrets on cmdline.
// 1) server can require no authentication -> // 1) server can require no authentication ->
// we must just provide a (possibly fake) reply address. // we must just provide a (possibly fake) reply address.
@ -241,8 +255,6 @@ int sendmail_main(int argc UNUSED_PARAM, char **argv)
// G.user = xuid2uname(getuid()); // G.user = xuid2uname(getuid());
// opt_from = xasprintf("%s@%s", G.user, domain); // opt_from = xasprintf("%s@%s", G.user, domain);
//} //}
//if (ENABLE_FEATURE_CLEAN_UP)
// free(domain);
smtp_checkp("MAIL FROM:<%s>", opt_from, 250); smtp_checkp("MAIL FROM:<%s>", opt_from, 250);
// process message // process message
@ -272,26 +284,26 @@ int sendmail_main(int argc UNUSED_PARAM, char **argv)
if (0 == strncasecmp("To:", s, 3) || 0 == strncasecmp("Bcc:" + 1, s, 3)) { if (0 == strncasecmp("To:", s, 3) || 0 == strncasecmp("Bcc:" + 1, s, 3)) {
rcptto(sane_address(s+3)); rcptto(sane_address(s+3));
goto addheader; goto addheader;
}
// Bcc: header adds blind copy (hidden) recipient // Bcc: header adds blind copy (hidden) recipient
} else if (0 == strncasecmp("Bcc:", s, 4)) { if (0 == strncasecmp("Bcc:", s, 4)) {
rcptto(sane_address(s+4)); rcptto(sane_address(s+4));
free(s); free(s);
// N.B. Bcc: vanishes from headers! // N.B. Bcc: vanishes from headers!
} else
// other headers go verbatim if (strchr(s, ':') || (list && skip_whitespace(s) != s)) {
// other headers go verbatim
// N.B. RFC2822 2.2.3 "Long Header Fields" allows for headers to occupy several lines. // N.B. RFC2822 2.2.3 "Long Header Fields" allows for headers to occupy several lines.
// Continuation is denoted by prefixing additional lines with whitespace(s). // Continuation is denoted by prefixing additional lines with whitespace(s).
// Thanks (stefan.seyfried at googlemail.com) for pointing this out. // Thanks (stefan.seyfried at googlemail.com) for pointing this out.
} else if (strchr(s, ':') || (list && skip_whitespace(s) != s)) {
addheader: addheader:
// N.B. we allow MAX_HEADERS generic headers at most to prevent attacks // N.B. we allow MAX_HEADERS generic headers at most to prevent attacks
if (MAX_HEADERS && ++nheaders >= MAX_HEADERS) if (MAX_HEADERS && ++nheaders >= MAX_HEADERS)
goto bail; goto bail;
llist_add_to_end(&list, s); llist_add_to_end(&list, s);
// a line without ":" (an empty line too, by definition) doesn't look like a valid header
// so stop "analyze headers" mode
} else { } else {
// a line without ":" (an empty line too, by definition) doesn't look like a valid header
// so stop "analyze headers" mode
reenter: reenter:
// put recipients specified on cmdline // put recipients specified on cmdline
while (*argv) { while (*argv) {