mikey: do not request more data on proto violation

Return value "-1" means that more data is requested. The dissector
actually doesn't have any idea what to do with the data, so just return
the data dissected so far.

tcp stream 3182 from c05-http-reply-r1.pcap (SampleCaptures) was
incorrectly detected as MIKEY, it was actually HTTP...

Change-Id: Idca3d3e2f85e821df70436a675699b5834236f89
Reviewed-on: https://code.wireshark.org/review/2887
Reviewed-by: Evan Huus <eapache@gmail.com>

1 files changed, 26 insertions, 12 deletions

diff --git a/epan/dissectors/packet-mikey.c b/epan/dissectors/packet-mikey.c
index 04b64ba628..621a32aada 100644
--- a/epan/dissectors/packet-mikey.c
+++ b/epan/dissectors/packet-mikey.c
@@ -683,7 +683,7 @@ dissect_payload_cs_id(int type, mikey_t *mikey, tvbuff_t *tvb, packet_info *pinf
 	entry = mikey_dissector_lookup(cs_id_map, type);
 
 	if (!entry || !entry->dissector) {
-		return -1;
+		return 0;
 	}
 
 	return entry->dissector(mikey, tvb, pinfo, tree);
@@ -733,7 +733,7 @@ dissect_payload_hdr(mikey_t *mikey, tvbuff_t *tvb, packet_info *pinfo, proto_tre
 		len = dissect_payload_cs_id(cs_id_map_type, mikey, sub_tvb, pinfo, tree);
 
 		if (len < 0)
-			return -1;
+			return 0;
 
 		offset += len;
 	}
@@ -785,7 +785,7 @@ dissect_payload_kemac(mikey_t *mikey, tvbuff_t *tvb, packet_info *pinfo, proto_t
 		mac_length = 160/8;
 		break;
 	default:
-		return -1;
+		return 0;
 	}
 
 	tvb_ensure_bytes_exist(tvb, offset+4+encr_length+1, mac_length);
@@ -840,7 +840,7 @@ dissect_payload_dh(mikey_t *mikey _U_, tvbuff_t *tvb, packet_info *pinfo _U_, pr
 		dh_length = 1024/8;
 		break;
 	default:
-		return -1;
+		return 0;
 	}
 
 	tvb_ensure_bytes_exist(tvb, offset+2, dh_length+1);
@@ -854,7 +854,7 @@ dissect_payload_dh(mikey_t *mikey _U_, tvbuff_t *tvb, packet_info *pinfo _U_, pr
 	}
 
 	if (kv != 0) {
-		return -1;
+		return 0;
 	}
 
 	return 2 + dh_length + 1;
@@ -908,7 +908,7 @@ dissect_payload_t(mikey_t *mikey _U_, tvbuff_t *tvb, packet_info *pinfo _U_, pro
 		len = 6;
 		break;
 	default:
-		len = -1;
+		len = 0;
 		break;
 	}
 
@@ -1028,7 +1028,7 @@ dissect_payload_v(mikey_t *mikey _U_, tvbuff_t *tvb, packet_info *pinfo _U_, pro
 		length = 160/8;
 		break;
 	default:
-		return -1;
+		return 0;
 	}
 
 	tvb_ensure_bytes_exist(tvb, offset+2, length);
@@ -1122,7 +1122,7 @@ dissect_payload_sp(mikey_t *mikey _U_, tvbuff_t *tvb, packet_info *pinfo _U_, pr
 		param_len = dissect_payload_sp_param(type, subtvb, tree);
 
 		if (param_len < 0)
-			return -1;
+			return 0;
 
 		sub_pos += param_len;
 	}
@@ -1336,7 +1336,7 @@ dissect_payload(int payload, mikey_t *mikey, tvbuff_t *tvb, packet_info *pinfo,
 	entry = mikey_dissector_lookup(payload_map, payload);
 
 	if (!entry || !entry->dissector) {
-		return -1;
+		return 0;
 	}
 
 	return entry->dissector(mikey, tvb, pinfo, tree);
@@ -1398,8 +1398,10 @@ dissect_mikey(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U
 		}
 
 		len = dissect_payload(payload, mikey, subtvb, pinfo, mikey_payload_tree);
-		if (len < 0) {
-			return -1;
+		if (len <= 0) {
+			/* protocol violation or invalid data, stop dissecting
+			 * but accept the data retrieved so far */
+			return tvb_captured_length(tvb);
 		}
 
 		if (sub_ti)
@@ -1424,7 +1426,7 @@ dissect_mikey(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U
 				val_to_str_ext_const(mikey->type, &data_type_vals_ext, "Unknown"));
 
 	/* Return the amount of data this dissector was able to dissect */
-	return tvb_length(tvb);
+	return tvb_captured_length(tvb);
 }
 
 
@@ -1946,3 +1948,15 @@ proto_reg_handoff_mikey(void)
 	mikey_udp_port = global_mikey_udp_port;
 	mikey_tcp_port = global_mikey_tcp_port;
 }
+/*
+ * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 8
+ * tab-width: 8
+ * indent-tabs-mode: t
+ * End:
+ *
+ * vi: set shiftwidth=8 tabstop=8 noexpandtab:
+ * :indentSize=8:tabSize=8:noTabs=false:
+ */