sendmail: yet another maintainer's update

3 files changed, 92 insertions, 125 deletions

diff --git a/include/usage.h b/include/usage.h
index e9770cea9..95cb69c73 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -1035,10 +1035,8 @@ USE_FEATURE_BRCTL_FANCY("\n" \
        "        -P password     Authenticate with specified password\n" \
        "        -X              Use openssl connection helper for secured servers\n" \
        "        -t              Get only headers\n" \
-       "        -z              Delete messages on server" \
-USE_FEATURE_FETCHMAIL_FILTER("\n" \
-       "        prog            Run prog <message file> on message delivery" \
-)
+       "        -z              Delete messages on server\n" \
+       "        prog            Run prog <message file> on message delivery"
 
 #define findfs_trivial_usage \
        "LABEL=label or UUID=uuid"
diff --git a/networking/Config.in b/networking/Config.in
index 202b65fce..3c53c1115 100644
--- a/networking/Config.in
+++ b/networking/Config.in
@@ -678,39 +678,11 @@ config SENDMAIL
         help
           Barebones sendmail.
 
-config FEATURE_SENDMAIL_EHLO
-        bool "Support EHLO command"
-        default n
-        depends on SENDMAIL
-        help
-          Support ESMTP EHLO command.
-
-config FEATURE_SENDMAIL_BLOATY
-        bool "Be more verbose"
-        default n
-        depends on SENDMAIL
-        help
-          Should be turned off.
-
 config FETCHMAIL
         bool "fetchmail"
         default n
         help
-          Barebone fetchmail.
-
-config FEATURE_FETCHMAIL_APOP
-        bool "Support APOP authentication"
-        default y
-        depends on FETCHMAIL
-        help
-          Support secure APOP authentication.
-
-config FEATURE_FETCHMAIL_FILTER
-        bool "Pipe through external filter"
-        default n
-        depends on FETCHMAIL
-        help
-          Support piping incoming messages through external filter.
+          Barebones fetchmail.
 
 config SLATTACH
         bool "slattach"
diff --git a/networking/sendmail.c b/networking/sendmail.c
index adc6c7626..3a6078f79 100644
--- a/networking/sendmail.c
+++ b/networking/sendmail.c
@@ -63,20 +63,13 @@ static void uuencode(char *fname, const char *text)
                 close(fd);
 }
 
-static const char *const init_xargs[9] = {
-        "openssl", "s_client", "-quiet", "-connect",
-        NULL, "-tls1", "-starttls", "smtp"
-};
-
 struct globals {
         pid_t helper_pid;
         unsigned timeout;
         // arguments for SSL connection helper
         const char *xargs[9];
-#if ENABLE_FEATURE_FETCHMAIL_FILTER
         // arguments for postprocess helper
         const char *fargs[3];
-#endif
 };
 #define G (*ptr_to_globals)
 #define helper_pid      (G.helper_pid)
@@ -85,16 +78,21 @@ struct globals {
 #define fargs           (G.fargs     )
 #define INIT_G() do { \
         PTR_TO_GLOBALS = xzalloc(sizeof(G)); \
-        memcpy(xargs, init_xargs, sizeof(init_xargs)); \
+        xargs[0] = "openssl"; \
+        xargs[1] = "s_client"; \
+        xargs[2] = "-quiet"; \
+        xargs[3] = "-connect"; \
+        /*xargs[4] = "server[:port]";*/ \
+        xargs[5] = "-tls1"; \
+        xargs[6] = "-starttls"; \
+        xargs[7] = "smtp"; \
         fargs[0] = "utf-8"; \
 } while (0)
 
 #define opt_connect       (xargs[4])
 #define opt_after_connect (xargs[5])
-#if ENABLE_FEATURE_FETCHMAIL_FILTER
 #define opt_charset       (fargs[0])
 #define opt_subject       (fargs[1])
-#endif
 
 static void kill_helper(void)
 {
@@ -116,11 +114,7 @@ static void signal_handler(int signo)
         // 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)
@@ -141,12 +135,11 @@ static void launch_helper(const char **argv)
                         if (pipes[i] > STDOUT_FILENO)
                                 close(pipes[i]);
         if (!helper_pid) {
-                // child - try to execute connection helper
-//              close(STDERR_FILENO);
+                // child: try to execute connection helper
                 BB_EXECVP(*argv, (char **)argv);
                 _exit(127);
         }
-        // parent - check whether child is alive
+        // parent: check whether child is alive
         bb_signals(0
                 + (1 << SIGCHLD)
                 + (1 << SIGALRM)
@@ -155,13 +148,12 @@ static void launch_helper(const char **argv)
         // child seems OK -> parent goes on
 }
 
-static char *command(const char *fmt, const char *param)
+static const char *command(const char *fmt, const char *param)
 {
-        char *msg = (char *)fmt;
+        const char *msg = fmt;
         alarm(timeout);
         if (msg) {
-//              if (param)
-                        msg = xasprintf(fmt, param);
+                msg = xasprintf(fmt, param);
                 printf("%s\r\n", msg);
         }
         fflush(stdout);
@@ -171,25 +163,20 @@ static char *command(const char *fmt, const char *param)
 static int smtp_checkp(const char *fmt, const char *param, int code)
 {
         char *answer;
-        char *msg = command(fmt, param);
+        const 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)) != NULL)
                 if (strlen(answer) <= 3 || '-' != answer[3])
                         break;
-#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) {
@@ -200,7 +187,7 @@ static int smtp_checkp(const char *fmt, const char *param, int code)
         bb_error_msg_and_die("%s failed", msg);
 }
 
-static int smtp_check(const char *fmt, int code)
+static int inline smtp_check(const char *fmt, int code)
 {
         return smtp_checkp(fmt, NULL, code);
 }
@@ -223,7 +210,7 @@ static char *sane(char *str)
 #if ENABLE_FETCHMAIL
 static void pop3_checkr(const char *fmt, const char *param, char **ret)
 {
-        char *msg = command(fmt, param);
+        const char *msg = command(fmt, param);
         char *answer = xmalloc_getline(stdin);
         if (answer && '+' == *answer) {
                 alarm(0);
@@ -237,7 +224,7 @@ static void pop3_checkr(const char *fmt, const char *param, char **ret)
         bb_error_msg_and_die("%s failed", msg);
 }
 
-static void pop3_check(const char *fmt, const char *param)
+static void inline pop3_check(const char *fmt, const char *param)
 {
         pop3_checkr(fmt, param, NULL);
 }
@@ -249,7 +236,7 @@ static void pop3_message(const char *filename)
         // create and open file filename
         // read stdin, copy to created file
         fd = xopen(filename, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL);
-        while ((answer = xmalloc_fgets_str(stdin, "\r\n"))) {
+        while ((answer = xmalloc_fgets_str(stdin, "\r\n")) != NULL) {
                 char *s = answer;
                 if ('.' == *answer) {
                         if ('.' == answer[1])
@@ -268,10 +255,6 @@ int sendgetmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int sendgetmail_main(int argc, char **argv)
 {
         llist_t *opt_recipients = NULL;
-#if !ENABLE_FEATURE_FETCHMAIL_FILTER
-        char *opt_subject;
-        char *opt_charset = (char *)"utf-8";
-#endif
 
         const char *opt_user;
         const char *opt_pass;
@@ -295,8 +278,12 @@ int sendgetmail_main(int argc, char **argv)
         const char *options;
         unsigned opts;
 
+        // init global variables
         INIT_G();
 
+        // parse options, different option sets for sendmail and fetchmail
+        // N.B. opt_after_connect hereafter is NULL if we are called as fetchmail
+        // and is NOT NULL if we are called as sendmail
         if (!ENABLE_FETCHMAIL || 's' == applet_name[0]) {
                 // SENDMAIL
                 // save initial stdin (body or attachements can be piped!)
@@ -313,7 +300,6 @@ int sendgetmail_main(int argc, char **argv)
                 &timeout, &opt_user, &opt_pass,
                 &opt_subject, &opt_charset, &opt_recipients
         );
-
         //argc -= optind;
         argv += optind;
 
@@ -321,20 +307,29 @@ int sendgetmail_main(int argc, char **argv)
         opt_connect = *argv++;
 
         // connect to server
+        // SSL ordered? ->
         if (opts & OPT_X) {
+                // ... use openssl helper
                 launch_helper(xargs);
+        // no SSL ordered? ->
         } else {
-                // no connection helper provided -> make plain connect
-                int fd = create_and_connect_stream_or_die(opt_connect, 0);
+                // ... make plain connect
+                int fd = create_and_connect_stream_or_die(opt_connect, 25);
+                // make ourselves a simple IO filter
+                // from now we know nothing about network :)
                 xmove_fd(fd, STDIN_FILENO);
                 xdup2(STDIN_FILENO, STDOUT_FILENO);
         }
 
 #if ENABLE_FETCHMAIL
+        // we are sendmail?
         if (opt_after_connect)
 #endif
         {
-                // SENDMAIL
+/***************************************************
+ * SENDMAIL
+ ***************************************************/
+
                 char *opt_from;
                 int code;
                 char *boundary;
@@ -342,44 +337,45 @@ int sendgetmail_main(int argc, char **argv)
                 const char *p;
                 char *q;
 
-                // wait for initial OK on plain connect
-                if (!(opts & OPT_X))
+                // we didn't use SSL helper? ->
+                if (!(opts & OPT_X)) {
+                        // ... wait for initial server OK
                         smtp_check(NULL, 220);
+                }
 
-                // get specified sender
+                // get the sender
                 opt_from = sane(*argv++);
 
                 // 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", opt_from, -1)) {
+                // we should start with modern EHLO
+                if (250 != smtp_checkp("EHLO %s", opt_from, -1)) {
                         smtp_checkp("HELO %s", opt_from, 250);
                 }
 
                 // set sender
-                // NOTE: if password has not been specified ->
-                // no authentication is possible
+                // NOTE: if password has not been specified
+                // then no authentication is possible
                 code = (opts & OPT_P) ? -1 : 250;
                 // first try softly without authentication
                 while (250 != smtp_checkp("MAIL FROM:<%s>", opt_from, code)) {
                         // MAIL FROM failed -> authentication needed
-                        // do we have username?
+                        // have we got username?
                         if (!(opts & OPT_U)) {
                                 // no! fetch it from "from" option
                                 //opts |= OPT_U;
                                 opt_user = xstrdup(opt_from);
                                 *strchrnul(opt_user, '@') = '\0';
                         }
-                        // now it seems we have username
-                        // try to authenticate
+                        // now we've got username
+                        // so 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
+                        // authenticated OK? -> retry to set sender
+                        // but this time die on failure!
                         code = 250;
                 }
 
@@ -388,13 +384,15 @@ int sendgetmail_main(int argc, char **argv)
                         smtp_checkp("RCPT TO:<%s>", sane(to->data), 250);
                 }
 
-                // now put message
+                // enter "put message" mode
                 smtp_check("DATA", 354);
+
                 // put address headers
                 printf("From: %s\r\n", opt_from);
                 for (llist_t *to = opt_recipients; to; to = to->link) {
                         printf("To: %s\r\n", to->data);
                 }
+
                 // put encoded subject
                 if (opts & OPTS_c)
                         sane((char *)opt_charset);
@@ -403,17 +401,17 @@ int sendgetmail_main(int argc, char **argv)
                         uuencode(NULL, opt_subject);
                         printf("?=\r\n");
                 }
+
                 // put notification
                 if (opts & OPTS_n)
                         printf("Disposition-Notification-To: %s\r\n", opt_from);
+
+                // make a random string -- it will delimit message parts
+                srand(monotonic_us());
+                boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
+
                 // put common headers and body start
-                // randomize
-#if ENABLE_FEATURE_SENDMAIL_BLOATY
-                srand(time(NULL));
-#endif
-                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"
@@ -421,8 +419,10 @@ int sendgetmail_main(int argc, char **argv)
                         , "Content-Type: "
                         , boundary
                 );
-                // put body + attachment(s)
 
+                // put body + attachment(s)
+                // N.B. all these weird things just to be tiny
+                // by reusing string patterns!
                 fmt =
                         "\r\n--%s\r\n"
                         "%stext/plain; charset=%s\r\n"
@@ -453,44 +453,50 @@ int sendgetmail_main(int argc, char **argv)
                                 q = bb_get_last_path_component_strip(*argv);
                 }
 
-                // put terminator
+                // put message 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);
+                // leave "put message" mode
+                smtp_check(".", 250);
+                // ... and say goodbye
                 smtp_check("QUIT", 221);
 
 #if ENABLE_FETCHMAIL
         } else {
-                // FETCHMAIL
+/***************************************************
+ * FETCHMAIL
+ ***************************************************/
+
                 char *buf;
                 unsigned nmsg;
                 char *hostname;
                 pid_t pid;
-                // cache fetch command
+
+                // cache fetch command:
+                // TOP will return only the headers
+                // RETR will dump the whole message
                 const char *retr = (opts & OPTF_t) ? "TOP %u 0" : "RETR %u";
 
                 // goto maildir
                 xchdir(*argv++);
 
-#if ENABLE_FEATURE_FETCHMAIL_FILTER
                 // cache postprocess program
                 *fargs = *argv;
-#endif
                 
                 // authenticate
                 if (!(opts & OPT_U)) {
                         //opts |= OPT_U;
-                        opt_user = getenv("USER");
+                        // N.B. IMHO getenv("USER") can be way easily spoofed!
+                        opt_user = bb_getpwuid(NULL, -1, getuid());
                 }
-#if ENABLE_FEATURE_FETCHMAIL_APOP
+
+                // get server greeting
                 pop3_checkr(NULL, NULL, &buf);
+
                 // server supports APOP?
                 if ('<' == *buf) {
                         md5_ctx_t md5;
-                        // yes. compose <stamp><password>
+                        // yes! compose <stamp><password>
                         char *s = strchr(buf, '>');
                         if (s)
                                 strcpy(s+1, opt_pass);
@@ -512,26 +518,22 @@ int sendgetmail_main(int argc, char **argv)
                                 free(s);
                                 free(buf-4); // buf is "+OK " away from malloc'ed string
                         }
+                // server ignores APOP -> use simple text authentication
                 } else {
-#else
-                {
-                        pop3_check(NULL, NULL);
-#endif
                         // USER
                         pop3_check("USER %s", opt_user);
                         // PASS
                         pop3_check("PASS %s", opt_pass);
                 }
 
-                // get statistics
+                // get mailbox statistics
                 pop3_checkr("STAT", NULL, &buf);
 
                 // prepare message filename suffix
-                hostname = xzalloc(MAXHOSTNAMELEN+1);
-                gethostname(hostname, MAXHOSTNAMELEN);
+                hostname = safe_gethostname();
                 pid = getpid();
 
-                // get number of messages
+                // get messages counter
                 // NOTE: we don't use xatou(buf) since buf is "nmsg nbytes"
                 // we only need nmsg and atoi is just exactly what we need
                 // if atoi fails to convert buf into number it returns 0
@@ -542,19 +544,19 @@ int sendgetmail_main(int argc, char **argv)
 
                 // loop through messages
                 for (; nmsg; nmsg--) {
+
+                        // generate unique filename
                         char *filename = xasprintf("tmp/%llu.%u.%s", monotonic_us(), pid, hostname);
                         char *target;
-#if ENABLE_FEATURE_FETCHMAIL_FILTER
-                int rc;
-#endif
-                        // retrieve message in ./tmp
+                        int rc;
+
+                        // retrieve message in ./tmp/
                         pop3_check(retr, (const char *)nmsg);
                         pop3_message(filename);
                         // delete message from server
                         if (opts & OPTF_z)
                                 pop3_check("DELE %u", (const char*)nmsg);
 
-#if ENABLE_FEATURE_FETCHMAIL_FILTER
                         // run postprocessing program
                         if (*fargs) {
                                 fargs[1] = filename;
@@ -564,23 +566,18 @@ int sendgetmail_main(int argc, char **argv)
                                 if (1 == rc)
                                         goto skip;
                         }
-#endif
-                        // atomically move message to ./new
+
+                        // atomically move message to ./new/
                         target = xstrdup(filename);
                         strncpy(target, "new", 3);
                         // ... or just stop receiving on error
                         if (rename_or_warn(filename, target))
                                 break;
                         free(target);
-#if ENABLE_FEATURE_FETCHMAIL_FILTER
  skip:
-#endif
                         free(filename);
                 }
 
-                if (ENABLE_FEATURE_CLEAN_UP)
-                        free(hostname);
-
                 // Bye
                 pop3_check("QUIT", NULL);
 #endif // ENABLE_FETCHMAIL