Drain socket to get clean TCP FINs

5 files changed, 88 insertions, 64 deletions

diff --git a/src/src/daemon.c b/src/src/daemon.c
index 64412c97d..a22ac8d68 100644
--- a/src/src/daemon.c
+++ b/src/src/daemon.c
@@ -523,9 +523,17 @@ if (pid == 0)
       }
     else
       {
+      int i;
+      uschar * buf[128];
       mac_smtp_fflush();
+      /* drain socket, for clean TCP FINs */
+      for(i = 16; read(fileno(smtp_in), buf, sizeof(buf)) > 0 && i > 0; ) i--;
       search_tidyup();
       smtp_log_no_mail();                 /* Log no mail if configured */
+
+      /*XXX should we pause briefly, hoping that the client will be the
+      active TCP closer hence get the TCP_WAIT endpoint? */
+      DEBUG(D_receive) debug_printf("SMTP>>(close on process exit)\n");
       _exit((rc == 0)? EXIT_SUCCESS : EXIT_FAILURE);
       }
 
diff --git a/src/src/smtp_in.c b/src/src/smtp_in.c
index 3b631ea10..9484105d6 100644
--- a/src/src/smtp_in.c
+++ b/src/src/smtp_in.c
@@ -325,6 +325,7 @@ smtp_getc(void)
 if (smtp_inptr >= smtp_inend)
   {
   int rc, save_errno;
+  if (!smtp_out) return EOF;
   fflush(smtp_out);
   if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
   rc = read(fileno(smtp_in), smtp_inbuffer, in_buffer_size);
@@ -1343,26 +1344,23 @@ if (smtp_in == NULL || smtp_batched_input) return;
 receive_swallow_smtp();
 smtp_printf("421 %s\r\n", message);
 
-for (;;)
+for (;;) switch(smtp_read_command(FALSE))
   {
-  switch(smtp_read_command(FALSE))
-    {
-    case EOF_CMD:
-    return;
+  case EOF_CMD:
+  return;
 
-    case QUIT_CMD:
-    smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
-    mac_smtp_fflush();
-    return;
+  case QUIT_CMD:
+  smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
+  mac_smtp_fflush();
+  return;
 
-    case RSET_CMD:
-    smtp_printf("250 Reset OK\r\n");
-    break;
+  case RSET_CMD:
+  smtp_printf("250 Reset OK\r\n");
+  break;
 
-    default:
-    smtp_printf("421 %s\r\n", message);
-    break;
-    }
+  default:
+  smtp_printf("421 %s\r\n", message);
+  break;
   }
 }
 
@@ -3403,7 +3401,7 @@ smtp_quit_handler(uschar ** user_msgp, uschar ** log_msgp)
 {
 HAD(SCH_QUIT);
 incomplete_transaction_log(US"QUIT");
-if (acl_smtp_quit != NULL)
+if (acl_smtp_quit)
   {
   int rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, user_msgp, log_msgp);
   if (rc == ERROR)
@@ -5026,45 +5024,39 @@ while (done <= 0)
     set, but we must still reject all incoming commands. */
 
     DEBUG(D_tls) debug_printf("TLS failed to start\n");
-    while (done <= 0)
+    while (done <= 0) switch(smtp_read_command(FALSE))
       {
-      switch(smtp_read_command(FALSE))
-        {
-        case EOF_CMD:
-        log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
-          smtp_get_connection_info());
-        smtp_notquit_exit(US"tls-failed", NULL, NULL);
-        done = 2;
-        break;
-
-        /* It is perhaps arguable as to which exit ACL should be called here,
-        but as it is probably a situation that almost never arises, it
-        probably doesn't matter. We choose to call the real QUIT ACL, which in
-        some sense is perhaps "right". */
+      case EOF_CMD:
+	log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
+	  smtp_get_connection_info());
+	smtp_notquit_exit(US"tls-failed", NULL, NULL);
+	done = 2;
+	break;
 
-        case QUIT_CMD:
-        user_msg = NULL;
-        if (acl_smtp_quit != NULL)
-          {
-          rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
-            &log_msg);
-          if (rc == ERROR)
-            log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
-              log_msg);
-          }
-        if (user_msg == NULL)
-          smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
-        else
-          smtp_respond(US"221", 3, TRUE, user_msg);
-        log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
-          smtp_get_connection_info());
-        done = 2;
-        break;
+      /* It is perhaps arguable as to which exit ACL should be called here,
+      but as it is probably a situation that almost never arises, it
+      probably doesn't matter. We choose to call the real QUIT ACL, which in
+      some sense is perhaps "right". */
+
+      case QUIT_CMD:
+	user_msg = NULL;
+	if (  acl_smtp_quit
+	   && ((rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
+			      &log_msg)) == ERROR))
+	    log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
+	      log_msg);
+	if (user_msg)
+	  smtp_respond(US"221", 3, TRUE, user_msg);
+	else
+	  smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
+	log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
+	  smtp_get_connection_info());
+	done = 2;
+	break;
 
-        default:
-        smtp_printf("554 Security failure\r\n");
-        break;
-        }
+      default:
+	smtp_printf("554 Security failure\r\n");
+	break;
       }
     tls_close(TRUE, TRUE);
     break;
diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c
index a5a680fd2..383a00f4e 100644
--- a/src/src/tls-gnu.c
+++ b/src/src/tls-gnu.c
@@ -1829,16 +1829,22 @@ alarm(0);
 
 if (rc != GNUTLS_E_SUCCESS)
   {
-  tls_error(US"gnutls_handshake",
-      sigalrm_seen ? "timed out" : gnutls_strerror(rc), NULL);
   /* It seems that, except in the case of a timeout, we have to close the
   connection right here; otherwise if the other end is running OpenSSL it hangs
   until the server times out. */
 
-  if (!sigalrm_seen)
+  if (sigalrm_seen)
+    tls_error(US"gnutls_handshake", "timed out", NULL);
+  else
     {
+    tls_error(US"gnutls_handshake", gnutls_strerror(rc), NULL);
+    gnutls_alert_send_appropriate(state->session, rc);
+    millisleep(500);
+    shutdown(fileno(smtp_out), SHUT_WR);
+    for (rc = 1024; fgetc(smtp_in) != EOF && rc > 0; ) rc--;	/* drain skt */
     (void)fclose(smtp_out);
     (void)fclose(smtp_in);
+    smtp_out = smtp_in = NULL;
     }
 
   return FAIL;
@@ -1863,8 +1869,7 @@ if (  state->verify_requirement != VERIFY_NONE
 
 /* Figure out peer DN, and if authenticated, etc. */
 
-rc = peer_status(state);
-if (rc != OK) return rc;
+if ((rc = peer_status(state)) != OK) return rc;
 
 /* Sets various Exim expansion variables; always safe within server */
 
@@ -2040,8 +2045,13 @@ do
 alarm(0);
 
 if (rc != GNUTLS_E_SUCCESS)
-  return tls_error(US"gnutls_handshake",
-      sigalrm_seen ? "timed out" : gnutls_strerror(rc), state->host);
+  if (sigalrm_seen)
+    {
+    gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_USER_CANCELED);
+    return tls_error(US"gnutls_handshake", "timed out", state->host);
+    }
+  else
+    return tls_error(US"gnutls_handshake", gnutls_strerror(rc), state->host);
 
 DEBUG(D_tls) debug_printf("gnutls_handshake was successful\n");
 
@@ -2118,7 +2128,7 @@ if (!state->tlsp || state->tlsp->active < 0) return;  /* TLS was not active */
 
 if (shutdown)
   {
-  DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS\n");
+  DEBUG(D_tls) debug_printf("tls_close() from '%s': shutting down TLS\n");
   gnutls_bye(state->session, GNUTLS_SHUT_WR);
   }
 
@@ -2168,11 +2178,19 @@ if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
     ssl_xfer_buffer_size);
   alarm(0);
 
-  /* A zero-byte return appears to mean that the TLS session has been
+  /* Timeouts do not get this far; see command_timeout_handler().
+     A zero-byte return appears to mean that the TLS session has been
      closed down, not that the socket itself has been closed down. Revert to
      non-TLS handling. */
 
-  if (inbytes == 0)
+  if (sigalrm_seen)
+    {
+    DEBUG(D_tls) debug_printf("Got tls read timeout\n");
+    state->xfer_error = 1;
+    return EOF;
+    }
+
+  else if (inbytes == 0)
     {
     DEBUG(D_tls) debug_printf("Got TLS_EOF\n");
 
diff --git a/src/src/tls-openssl.c b/src/src/tls-openssl.c
index 64dcab600..d9db7243f 100644
--- a/src/src/tls-openssl.c
+++ b/src/src/tls-openssl.c
@@ -2504,7 +2504,7 @@ if (*fdp < 0) return;  /* TLS was not active */
 
 if (shutdown)
   {
-  DEBUG(D_tls) debug_printf("tls_close(): shutting down SSL\n");
+  DEBUG(D_tls) debug_printf("tls_close() from '%s': shutting down SSL\n");
   SSL_shutdown(*sslp);
   }
 
diff --git a/src/src/transports/smtp.c b/src/src/transports/smtp.c
index 21c57209c..ecdb8bf26 100644
--- a/src/src/transports/smtp.c
+++ b/src/src/transports/smtp.c
@@ -3162,6 +3162,12 @@ specified in the transports, and therefore not visible at top level, in which
 case continue_more won't get set. */
 
 HDEBUG(D_transport|D_acl|D_v) debug_printf("  SMTP(close)>>\n");
+if (lflags.send_quit)
+  {
+  shutdown(outblock.sock, SHUT_WR);
+  for (rc = 16; read(inblock.sock, inbuffer, sizeof(inbuffer)) > 0 && rc > 0;)
+    rc--;				/* drain socket */
+  }
 (void)close(inblock.sock);
 
 #ifndef DISABLE_EVENT