pimd: non-null register checksum incorrect

Ticket: CM-12041
Reviewed By: sharpd, CCR-5556
Testing Done: Tested on Local setup generating PIM Register (Data/Null) and processing both Tx/Rx with correct checksum.
Provided quagga debian to submitter and checksum cases passed on submitter setup.

1. PIM Register msg checksum only accounts for 8 bytes (4 bytes for PIM header and next 4 byetes before data payload).
In PIM header checksum calculation checked PIM packet type (in this case REGISTER type) then only pass 8 bytes as length
rather than full packet length.
2. PIM Register Rx path also handled with 8 byte and full pim lenth checksum.

Signed-off-by: Chirag Shah <chirag@cumulusnetworks.com>

1 files changed, 31 insertions, 7 deletions

diff --git a/pimd/pim_pim.c b/pimd/pim_pim.c
index f727d3e627..840004c375 100644
--- a/pimd/pim_pim.c
+++ b/pimd/pim_pim.c
@@ -197,13 +197,37 @@ int pim_pim_packet(struct interface *ifp, uint8_t *buf, size_t len)
   /* for computing checksum */
   *(uint16_t *) PIM_MSG_HDR_OFFSET_CHECKSUM(pim_msg) = 0;
 
-  checksum = in_cksum(pim_msg, pim_msg_len);
-  if (checksum != pim_checksum) {
-    if (PIM_DEBUG_PIM_PACKETS)
-      zlog_debug("Ignoring PIM pkt from %s with invalid checksum: received=%x calculated=%x",
-		 ifp->name, pim_checksum, checksum);
-    return -1;
-  }
+  if (pim_type == PIM_MSG_TYPE_REGISTER)
+    {
+      /* First 8 byte header checksum */
+      checksum = in_cksum (pim_msg, PIM_MSG_REGISTER_LEN);
+      if (checksum != pim_checksum)
+        {
+          checksum = in_cksum (pim_msg, pim_msg_len);
+          if (checksum != pim_checksum)
+            {
+              if (PIM_DEBUG_PIM_PACKETS)
+                zlog_debug
+                  ("Ignoring PIM pkt from %s with invalid checksum: received=%x calculated=%x",
+                   ifp->name, pim_checksum, checksum);
+
+              return -1;
+            }
+        }
+    }
+  else
+    {
+      checksum = in_cksum (pim_msg, pim_msg_len);
+      if (checksum != pim_checksum)
+        {
+          if (PIM_DEBUG_PIM_PACKETS)
+            zlog_debug
+              ("Ignoring PIM pkt from %s with invalid checksum: received=%x calculated=%x",
+               ifp->name, pim_checksum, checksum);
+
+          return -1;
+        }
+    }
 
   if (PIM_DEBUG_PIM_PACKETS) {
     pim_inet4_dump("<src?>", ip_hdr->ip_src, src_str, sizeof(src_str));