[PATCH] IPVS sync endianess fixed

[Justin Ossevoort <justin@xxxxxxxxxxxxxx>]

Hello,

 There was a small bug in the ip_vs_sync.c code that made it impossible
for 2 servers of different endian to sync with eachother (eg. a sparc
(big endian) and a i386 (little endian) based system). The problem was
in the message size. All other data seems to be correctly rearranged to
network byte order except for this one (probably because the size is
used from the moment the data is being gathered to the moment it is send).
 This caused "IPVS: bogus message" messages in my dmesg.

 This patch fixes this problem by converting the m->size at the last
moment before sending it to network byte order. And changing it back to
host order right before the message is processed. The patch is made
agains the Linux kernel version 2.6.8.1.

--[ Patch: Start Snip ]--

--- linux-2.6.8.1/net/ipv4/ipvs/ip_vs_sync.c    2004-08-14
12:54:46.000000000 +0200
+++ linux-2.6.8.1-fix/net/ipv4/ipvs/ip_vs_sync.c    2004-09-30
11:54:53.000000000 +0200
@@ -16,6 +16,7 @@
  *    Alexandre Cassen    :    Added master & backup support at a time.
  *    Alexandre Cassen    :    Added SyncID support for incoming sync
  *                    messages filtering.
+ *    Justin Ossevoort    :    Fix endian problem on sync message size.
  */

 #include <linux/module.h>
@@ -279,6 +280,9 @@
     char *p;
     int i;

+    /* Convert size back to host byte order */
+    m->size = ntohs(m->size);
+
     if (buflen != m->size) {
         IP_VS_ERR("bogus message\n");
         return;
@@ -569,6 +573,23 @@
     return len;
 }

+static void
+ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_buff *sb)
+{
+    int msize;
+    struct ip_vs_sync_mesg *m;
+
+    m = sb->mesg;
+    msize = m->size;
+
+    /* Put size in network byte order */
+    m->size = htons(m->size);
+
+    if (ip_vs_send_async(sock, (char *)m, msize) != msize)
+        IP_VS_ERR("ip_vs_send_async error\n");
+
+    ip_vs_sync_buff_release(sb);
+}

 static int
 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
@@ -605,7 +626,6 @@
 {
     struct socket *sock;
     struct ip_vs_sync_buff *sb;
-    struct ip_vs_sync_mesg *m;

     /* create the sending multicast socket */
     sock = make_send_sock();
@@ -618,20 +638,12 @@

     for (;;) {
         while ((sb=sb_dequeue())) {
-            m = sb->mesg;
-            if (ip_vs_send_async(sock, (char *)m,
-                         m->size) != m->size)
-                IP_VS_ERR("ip_vs_send_async error\n");
-            ip_vs_sync_buff_release(sb);
+            ip_vs_send_sync_msg(sock, sb);
         }

         /* check if entries stay in curr_sb for 2 seconds */
         if ((sb = get_curr_sync_buff(2*HZ))) {
-            m = sb->mesg;
-            if (ip_vs_send_async(sock, (char *)m,
-                         m->size) != m->size)
-                IP_VS_ERR("ip_vs_send_async error\n");
-            ip_vs_sync_buff_release(sb);
+            ip_vs_send_sync_msg(sock, sb);
         }

         if (stop_master_sync)

--[ Patch: End Snip ]--

Special credit goes to: Byte Internetdiensten (my current employer) for
supplying the testbed that triggered this bug and the time sponsored to
fix it.

ps.
Congratulations on the great work, the code is good and the
functionality great :)

--- linux-2.6.8.1/net/ipv4/ipvs/ip_vs_sync.c    2004-08-14 12:54:46.000000000 
+0200
+++ linux-2.6.8.1-fix/net/ipv4/ipvs/ip_vs_sync.c        2004-09-30 
11:54:53.000000000 +0200
@@ -16,6 +16,7 @@
  *     Alexandre Cassen        :       Added master & backup support at a time.
  *     Alexandre Cassen        :       Added SyncID support for incoming sync
  *                                     messages filtering.
+ *     Justin Ossevoort        :       Fix endian problem on sync message size.
  */
 
 #include <linux/module.h>
@@ -279,6 +280,9 @@
        char *p;
        int i;
 
+       /* Convert size back to host byte order */
+       m->size = ntohs(m->size);
+
        if (buflen != m->size) {
                IP_VS_ERR("bogus message\n");
                return;
@@ -569,6 +573,23 @@
        return len;
 }
 
+static void
+ip_vs_send_sync_msg(struct socket *sock, struct ip_vs_sync_buff *sb)
+{
+       int msize;
+       struct ip_vs_sync_mesg *m;
+
+       m = sb->mesg;
+       msize = m->size;
+
+       /* Put size in network byte order */
+       m->size = htons(m->size);
+
+       if (ip_vs_send_async(sock, (char *)m, msize) != msize)
+               IP_VS_ERR("ip_vs_send_async error\n");
+       
+       ip_vs_sync_buff_release(sb);
+}
 
 static int
 ip_vs_receive(struct socket *sock, char *buffer, const size_t buflen)
@@ -605,7 +626,6 @@
 {
        struct socket *sock;
        struct ip_vs_sync_buff *sb;
-       struct ip_vs_sync_mesg *m;
 
        /* create the sending multicast socket */
        sock = make_send_sock();
@@ -618,20 +638,12 @@
 
        for (;;) {
                while ((sb=sb_dequeue())) {
-                       m = sb->mesg;
-                       if (ip_vs_send_async(sock, (char *)m,
-                                            m->size) != m->size)
-                               IP_VS_ERR("ip_vs_send_async error\n");
-                       ip_vs_sync_buff_release(sb);
+                       ip_vs_send_sync_msg(sock, sb);
                }
 
                /* check if entries stay in curr_sb for 2 seconds */
                if ((sb = get_curr_sync_buff(2*HZ))) {
-                       m = sb->mesg;
-                       if (ip_vs_send_async(sock, (char *)m,
-                                            m->size) != m->size)
-                               IP_VS_ERR("ip_vs_send_async error\n");
-                       ip_vs_sync_buff_release(sb);
+                       ip_vs_send_sync_msg(sock, sb);
                }
 
                if (stop_master_sync)