From 42aad279a7467d9369fc88aff3d03e7e362308cc Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Fri, 31 Dec 2010 16:27:09 +0100
Subject: [PATCH] Cleaned up parsing of packets

---
 nwhod.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/nwhod.c b/nwhod.c
index 4f348e6..af38e85 100644
--- a/nwhod.c
+++ b/nwhod.c
@@ -218,25 +218,23 @@ receive(void)
 
   if (!is_valid(sa.sin_addr.s_addr) || sa.sin_port != port)
     {
-      syslog(LOG_WARNING, "Received packet from invalid source %s.%d", inet_ntoa(sa.sin_addr), ntohs(sa.sin_port));
+      syslog(LOG_WARNING, "Received packet from invalid source %s:%d", inet_ntoa(sa.sin_addr), ntohs(sa.sin_port));
       return;
     }
 
-  if (r < n || r != n + ntohl(pkt.num_users)*sizeof(struct userinfo))
+  if (r < n ||
+      pkt.magic != htonl(NWHO_MAGIC) ||
+      ntohl(pkt.num_users) > MAX_USERS ||
+      r != n + ntohl(pkt.num_users)*sizeof(struct userinfo))
     {
       syslog(LOG_WARNING, "Malformed packet from %s", inet_ntoa(sa.sin_addr));
       return;
     }
 
-  if (pkt.magic != htonl(NWHO_MAGIC))
-    {
-      syslog(LOG_WARNING, "Received ancient nwho packet from %s", inet_ntoa(sa.sin_addr));
-      return;
-    }
-
   for(e=first_host; e; e=e->next)
     if (e->addr == sa.sin_addr.s_addr)
       break;
+
   if (!e)
     {
       e = malloc(sizeof(struct hostrec));
@@ -250,8 +248,8 @@ receive(void)
       h = gethostbyaddr((char *) &sa.sin_addr, sizeof(sa.sin_addr), AF_INET);
       if (h)
 	{
-	  sprintf(e->name, "%.30s", h->h_name);
-	  for(c=e->name; *c; c++)
+	  snprintf(e->name, sizeof(e->name), "%s", h->h_name);
+	  for (c=e->name; *c; c++)
 	    if (*c == '.')
 	      {
 		*c = 0;
-- 
2.39.2