decode/pppoe: CDPCP as a known protocol

Cisco Discovery Protocol Control Protocol may be sent over pppoe.
We should allow it to help network functions.

src/decode-ppp.c

@@ -138,6 +138,7 @@ static int DecodePPPUncompressedProto(ThreadVars *tv, DecodeThreadVars *dtv, Pac
         case PPP_LQM:
         case PPP_CBCP:
         case PPP_COMP_DGRAM:
+        case PPP_CDPCP:
             /* Valid types to be in PPP but don't inspect validity. */
             return TM_ECODE_OK;
 

src/decode-ppp.h

@@ -54,6 +54,7 @@
 #define PPP_STIICP     0x8033 /* Stream Protocol Control Protocol */
 #define PPP_VINESCP    0x8035 /* Banyan Vines Control Protocol */
 #define PPP_IPV6CP     0x8057 /* IPv6 Control Protocol */
+#define PPP_CDPCP      0x8207 /* Cisco Discovery Protocol Control Protocol */
 #define PPP_MPLSCP     0x8281 /* rfc 3022 */
 #define PPP_LCP        0xc021 /* Link Control Protocol */
 #define PPP_PAP        0xc023 /* Password Authentication Protocol */

src/decode-pppoe.c

@@ -199,6 +199,7 @@ int DecodePPPOESession(
             case PPP_LQM:
             case PPP_CBCP:
             case PPP_COMP_DGRAM:
+            case PPP_CDPCP:
                 /* Valid types to be in PPP but don't inspect validity. */
                 break;