Print checksum in hex, and print the actual checksum, plus cleanup

diff --git a/print-cdp.c b/print-cdp.c
index 116f0fa522e8a07d502effee29a3be12479b1da1..c5fc8b11997793cdd32a9925a54edfbb9123947b 100644 (file)
--- a/print-cdp.c
+++ b/print-cdp.c
@@ -40,7 +40,8 @@
 
 static const char tstr[] = "[|cdp]";
 
-#define CDP_HEADER_LEN  4
+#define CDP_HEADER_LEN     4
+#define CDP_HEADER_OFFSET  2
 
 static const struct tok cdp_tlv_values[] = {
     { 0x01,             "Device-ID"},
@@ -99,15 +100,15 @@ cdp_print(netdissect_options *ndo,
        ND_TCHECK2(*tptr, CDP_HEADER_LEN);
        ND_PRINT((ndo, "CDPv%u, ttl: %us", *tptr, *(tptr + 1)));
        if (ndo->ndo_vflag)
-               ND_PRINT((ndo, ", checksum: %u (unverified), length %u", EXTRACT_16BITS(tptr), length));
+               ND_PRINT((ndo, ", checksum: 0x%04x (unverified), length %u", EXTRACT_16BITS(tptr+CDP_HEADER_OFFSET), length));
        tptr += CDP_HEADER_LEN;
 
        while (tptr < (pptr+length)) {
-               ND_TCHECK2(*tptr, 4); /* read out Type and Length */
+               ND_TCHECK2(*tptr, CDP_HEADER_LEN); /* read out Type and Length */
                type = EXTRACT_16BITS(tptr);
-               len  = EXTRACT_16BITS(tptr+2); /* object length includes the 4 bytes header length */
-                tptr += 4;
-                len -= 4;
+               len  = EXTRACT_16BITS(tptr+CDP_HEADER_OFFSET); /* object length includes the 4 bytes header length */
+                tptr += CDP_HEADER_LEN;
+                len -= CDP_HEADER_LEN;
 
                ND_TCHECK2(*tptr, len);
 
@@ -163,15 +164,15 @@ cdp_print(netdissect_options *ndo,
                        break;
                     case 0x08: /* Protocol Hello Option - not documented */
                        break;
-                    case 0x09: /* VTP Mgmt Domain  - not documented */
+                    case 0x09: /* VTP Mgmt Domain  - CDPv2 */
                         ND_PRINT((ndo, "'"));
                         fn_printn(ndo, tptr, len, NULL);
                         ND_PRINT((ndo, "'"));
                        break;
-                    case 0x0a: /* Native VLAN ID - not documented */
+                    case 0x0a: /* Native VLAN ID - CDPv2 */
                        ND_PRINT((ndo, "%d", EXTRACT_16BITS(tptr)));
                        break;
-                    case 0x0b: /* Duplex - not documented */
+                    case 0x0b: /* Duplex - CDPv2 */
                        ND_PRINT((ndo, "%s", *(tptr) ? "full": "half"));
                        break;