Properly handle SMTP server responses which are split into multiple

packets (noted by Chris Adams on nagiosplug-help@).  TODO: The new
recvline()/recvlines() functions should buffer received data instead of
reading one byte at a time and they should be moved to netutils.c so
that other plugins can use them, too.


git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1780 f882894a-f735-0410-b71e-b25c423dba1c

2 files changed, 73 insertions, 18 deletions

diff --git a/NEWS b/NEWS
index b687f6ff..d9ec3f66 100644
--- a/NEWS
+++ b/NEWS
@@ -15,6 +15,7 @@ This file documents the major additions and syntax changes between releases.
           address to use in the DHCP request
         The check_dhcp -r and -s options now accept host names, too
         Fix possible check_icmp bus errors on some (non-x86/AMD64) platforms
+        Fix check_smtp's handling of multiple-packet server responses
 
 1.4.9 4th June 2006
         Inclusion of contrib/check_cluster2 as check_cluster with some improvements
diff --git a/plugins/check_smtp.c b/plugins/check_smtp.c
index 8d392cc6..79c7cd35 100644
--- a/plugins/check_smtp.c
+++ b/plugins/check_smtp.c
@@ -40,6 +40,8 @@ const char *revision = "$Revision$";
 const char *copyright = "2000-2006";
 const char *email = "nagiosplug-devel@lists.sourceforge.net";
 
+#include <ctype.h>
+
 #include "common.h"
 #include "netutils.h"
 #include "utils.h"
@@ -75,6 +77,8 @@ int validate_arguments (void);
 void print_help (void);
 void print_usage (void);
 void smtp_quit(void);
+int recvline(char *, size_t);
+int recvlines(char *, size_t);
 int my_close(void);
 
 #include "regex.h"
@@ -116,7 +120,6 @@ char buffer[MAX_INPUT_BUFFER];
 enum {
   TCP_PROTOCOL = 1,
   UDP_PROTOCOL = 2,
-  MAXBUF = 1024
 };
 
 /* written by lauri alanko */
@@ -222,7 +225,7 @@ main (int argc, char **argv)
 
                 /* watch for the SMTP connection string and */
                 /* return a WARNING status if we couldn't read any data */
-                if (recv (sd, buffer, MAX_INPUT_BUFFER - 1, 0) == -1) {
+                if (recvlines(buffer, MAX_INPUT_BUFFER) <= 0) {
                         printf (_("recv() failed\n"));
                         result = STATE_WARNING;
                 }
@@ -246,11 +249,10 @@ main (int argc, char **argv)
                 send(sd, helocmd, strlen(helocmd), 0);
 
                 /* allow for response to helo command to reach us */
-                if(read (sd, buffer, MAXBUF - 1) < 0){
+                if (recvlines(buffer, MAX_INPUT_BUFFER) <= 0) {
                         printf (_("recv() failed\n"));
                         return STATE_WARNING;
                 } else if(use_ehlo){
-                        buffer[MAXBUF-1]='\0';
                         if(strstr(buffer, "250 STARTTLS") != NULL ||
                            strstr(buffer, "250-STARTTLS") != NULL){
                                 supports_tls=TRUE;
@@ -268,7 +270,7 @@ main (int argc, char **argv)
                   /* send the STARTTLS command */
                   send(sd, SMTP_STARTTLS, strlen(SMTP_STARTTLS), 0);
 
-                  recv(sd,buffer, MAX_INPUT_BUFFER-1, 0); /* wait for it */
+                  recvlines(buffer, MAX_INPUT_BUFFER); /* wait for it */
                   if (!strstr (buffer, server_expect)) {
                     printf (_("Server does not support STARTTLS\n"));
                     smtp_quit();
@@ -302,13 +304,12 @@ main (int argc, char **argv)
                 }
                 if (verbose)
                         printf(_("sent %s"), helocmd);
-                if ((n = my_recv(buffer, MAX_INPUT_BUFFER - 1)) <= 0) {
+                if ((n = recvlines(buffer, MAX_INPUT_BUFFER)) <= 0) {
                         printf("%s\n", _("SMTP UNKNOWN - Cannot read EHLO response via TLS."));
                         my_close();
                         return STATE_UNKNOWN;
                 }
                 if (verbose) {
-                        buffer[n] = '\0';
                         printf("%s", buffer);
                 }
 
@@ -337,16 +338,14 @@ main (int argc, char **argv)
                  */
                 if (smtp_use_dummycmd) {
                   my_send(cmd_str, strlen(cmd_str));
-                  my_recv(buffer, MAX_INPUT_BUFFER-1);
-                  if (verbose) 
+                  if (recvlines(buffer, MAX_INPUT_BUFFER) >= 1 && verbose)
                     printf("%s", buffer);
                 }
 
                 while (n < ncommands) {
                         asprintf (&cmd_str, "%s%s", commands[n], "\r\n");
                         my_send(cmd_str, strlen(cmd_str));
-                        my_recv(buffer, MAX_INPUT_BUFFER-1);
-                        if (verbose) 
+                        if (recvlines(buffer, MAX_INPUT_BUFFER) >= 1 && verbose)
                                 printf("%s", buffer);
                         strip (buffer);
                         if (n < nresponses) {
@@ -395,12 +394,11 @@ main (int argc, char **argv)
                                         if (verbose)
                                                 printf (_("sent %s\n"), "AUTH LOGIN");
 
-                                        if((ret = my_recv(buffer, MAXBUF - 1)) < 0){
+                                        if ((ret = recvlines(buffer, MAX_INPUT_BUFFER)) <= 0) {
                                                 asprintf(&error_msg, _("recv() failed after AUTH LOGIN, "));
                                                 result = STATE_WARNING;
                                                 break;
                                         }
-                                        buffer[ret] = 0;
                                         if (verbose)
                                                 printf (_("received %s\n"), buffer);
 
@@ -417,12 +415,11 @@ main (int argc, char **argv)
                                         if (verbose)
                                                 printf (_("sent %s\n"), abuf);
 
-                                        if ((ret = my_recv(buffer, MAX_INPUT_BUFFER-1)) == -1) {
+                                        if ((ret = recvlines(buffer, MAX_INPUT_BUFFER)) <= 0) {
                                                 result = STATE_CRITICAL;
                                                 asprintf(&error_msg, _("recv() failed after sending authuser, "));
                                                 break;
                                         }
-                                        buffer[ret] = 0;
                                         if (verbose) {
                                                 printf (_("received %s\n"), buffer);
                                         }
@@ -438,12 +435,11 @@ main (int argc, char **argv)
                                         if (verbose) {
                                                 printf (_("sent %s\n"), abuf);
                                         }
-                                        if ((ret = my_recv(buffer, MAX_INPUT_BUFFER-1)) == -1) {
+                                        if ((ret = recvlines(buffer, MAX_INPUT_BUFFER)) <= 0) {
                                                 result = STATE_CRITICAL;
                                                 asprintf(&error_msg, _("recv() failed after sending authpass, "));
                                                 break;
                                         }
-                                        buffer[ret] = 0;
                                         if (verbose) {
                                                 printf (_("received %s\n"), buffer);
                                         }
@@ -715,7 +711,7 @@ smtp_quit(void)
                 printf(_("sent %s\n"), "QUIT");
 
         /* read the response but don't care about problems */
-        bytes = my_recv(buffer, MAXBUF - 1);
+        bytes = recvlines(buffer, MAX_INPUT_BUFFER);
         if (verbose) {
                 if (bytes < 0)
                         printf(_("recv() failed after QUIT."));
@@ -729,6 +725,64 @@ smtp_quit(void)
 }
 
 
+/*
+ * Receive one line, copy it into buf and nul-terminate it.  Returns the
+ * number of bytes written to buf (excluding the '\0') or 0 on EOF or <0 on
+ * error.
+ *
+ * TODO: Reading one byte at a time is very inefficient.  Replace this by a
+ * function which buffers the data, move that to netutils.c and change
+ * check_smtp and other plugins to use that.  Also, remove (\r)\n.
+ */
+int
+recvline(char *buf, size_t bufsize)
+{
+        int result;
+        unsigned i;
+
+        for (i = result = 0; i < bufsize - 1; i++) {
+                if ((result = my_recv(&buf[i], 1)) != 1)
+                        break;
+                if (buf[i] == '\n') {
+                        buf[++i] = '\0';
+                        return i;
+                }
+        }
+        return (result == 1 || i == 0) ? -2 : result;   /* -2 if out of space */
+}
+
+
+/*
+ * Receive one or more lines, copy them into buf and nul-terminate it.  Returns
+ * the number of bytes written to buf (excluding the '\0') or 0 on EOF or <0 on
+ * error.  Works for all protocols which format multiline replies as follows:
+ *
+ * ``The format for multiline replies requires that every line, except the last,
+ * begin with the reply code, followed immediately by a hyphen, `-' (also known
+ * as minus), followed by text.  The last line will begin with the reply code,
+ * followed immediately by <SP>, optionally some text, and <CRLF>.  As noted
+ * above, servers SHOULD send the <SP> if subsequent text is not sent, but
+ * clients MUST be prepared for it to be omitted.'' (RFC 2821, 4.2.1)
+ *
+ * TODO: Move this to netutils.c.  Also, remove \r and possibly the final \n.
+ */
+int
+recvlines(char *buf, size_t bufsize)
+{
+        int result, i;
+
+        for (i = 0; /* forever */; i += result)
+                if (!((result = recvline(buf + i, bufsize - i)) > 3 &&
+                    isdigit((int)buf[i]) &&
+                    isdigit((int)buf[i + 1]) &&
+                    isdigit((int)buf[i + 2]) &&
+                    buf[i + 3] == '-'))
+                        break;
+
+        return (result <= 0) ? result : result + i;
+}
+
+
 int 
 my_close (void)
 {