CoAP: Refactor code, option and payload dissection

OSCORE plaintext contains CoAP code, some CoAP options and CoAP payload.
To avoid code duplication, CoAP dissection of these fields used by
OSCORE is generalized and exported in packet-coap.h. Exported functions
and their subroutines now operate explicitly on local variables. This
allows OSCORE dissector to pass its header fields.

Use of "offset_end" instead of "coap_length" to denote the end of
message.

Bug: 14417
Change-Id: If51b0d585ab29d46c1c550fbf264fd3765ed4c32
Reviewed-on: https://code.wireshark.org/review/25482
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

1 files changed, 168 insertions, 415 deletions

diff --git a/epan/dissectors/packet-coap.c b/epan/dissectors/packet-coap.c
index e1677ab038..9819a85322 100644
--- a/epan/dissectors/packet-coap.c
+++ b/epan/dissectors/packet-coap.c
@@ -38,48 +38,7 @@ static int hf_coap_version					= -1;
 static int hf_coap_ttype					= -1;
 static int hf_coap_token_len					= -1;
 static int hf_coap_token					= -1;
-static int hf_coap_code						= -1;
 static int hf_coap_mid						= -1;
-static int hf_coap_payload					= -1;
-static int hf_coap_payload_desc					= -1;
-static int hf_coap_payload_length				= -1;
-static int hf_coap_opt_name					= -1;
-static int hf_coap_opt_desc					= -1;
-static int hf_coap_opt_delta					= -1;
-static int hf_coap_opt_delta_ext				= -1;
-static int hf_coap_opt_length					= -1;
-static int hf_coap_opt_length_ext				= -1;
-static int hf_coap_opt_end_marker				= -1;
-static int hf_coap_opt_ctype					= -1;
-static int hf_coap_opt_max_age					= -1;
-static int hf_coap_opt_proxy_uri				= -1;
-static int hf_coap_opt_proxy_scheme				= -1;
-static int hf_coap_opt_size1					= -1;
-static int hf_coap_opt_etag					= -1;
-static int hf_coap_opt_uri_host					= -1;
-static int hf_coap_opt_location_path				= -1;
-static int hf_coap_opt_uri_port					= -1;
-static int hf_coap_opt_location_query				= -1;
-static int hf_coap_opt_uri_path					= -1;
-static int hf_coap_opt_uri_path_recon				= -1;
-static int hf_coap_opt_observe					= -1;
-static int hf_coap_opt_accept					= -1;
-static int hf_coap_opt_if_match					= -1;
-static int hf_coap_opt_block_number				= -1;
-static int hf_coap_opt_block_mflag				= -1;
-static int hf_coap_opt_block_size				= -1;
-static int hf_coap_opt_uri_query				= -1;
-static int hf_coap_opt_unknown					= -1;
-static int hf_coap_opt_object_security_non_compressed		= -1;
-static int hf_coap_opt_object_security_expand			= -1;
-static int hf_coap_opt_object_security_signature		= -1;
-static int hf_coap_opt_object_security_kid_context_present	= -1;
-static int hf_coap_opt_object_security_kid_present		= -1;
-static int hf_coap_opt_object_security_piv_len			= -1;
-static int hf_coap_opt_object_security_piv			= -1;
-static int hf_coap_opt_object_security_kid_context_len		= -1;
-static int hf_coap_opt_object_security_kid_context		= -1;
-static int hf_coap_opt_object_security_kid			= -1;
 
 static int hf_coap_response_in					= -1;
 static int hf_coap_response_to					= -1;
@@ -89,13 +48,8 @@ static int hf_coap_oscore_kid_context				= -1;
 static int hf_coap_oscore_piv					= -1;
 
 static gint ett_coap						= -1;
-static gint ett_coap_option					= -1;
-static gint ett_coap_payload					= -1;
 
-static expert_field ei_coap_invalid_option_number		= EI_INIT;
-static expert_field ei_coap_invalid_option_range		= EI_INIT;
-static expert_field ei_coap_option_length_bad			= EI_INIT;
-static expert_field ei_coap_option_object_security_bad		= EI_INIT;
+static COAP_COMMON_LIST_T(dissect_coap_hf);
 
 static dissector_handle_t coap_handle;
 static dissector_handle_t oscore_handle;
@@ -108,19 +62,6 @@ static dissector_handle_t oscore_handle;
 #define DEFAULT_COAP_CTYPE_VALUE				~0U
 #define DEFAULT_COAP_BLOCK_NUMBER				~0U
 
-/* bitmasks */
-#define COAP_VERSION_MASK					0xC0
-#define COAP_TYPE_MASK						0x30
-#define COAP_TOKEN_LEN_MASK					0x0F
-#define COAP_BLOCK_MFLAG_MASK					0x08
-#define COAP_BLOCK_SIZE_MASK					0x07
-#define COAP_OBJECT_SECURITY_NON_COMPRESSED_MASK		0x80
-#define COAP_OBJECT_SECURITY_EXPAND_MASK			0x40
-#define COAP_OBJECT_SECURITY_SIGNATURE_MASK			0x20
-#define COAP_OBJECT_SECURITY_KID_CONTEXT_MASK			0x10
-#define COAP_OBJECT_SECURITY_KID_MASK				0x08
-#define COAP_OBJECT_SECURITY_PIVLEN_MASK			0x07
-
 /*
  * Transaction Type
  */
@@ -184,9 +125,9 @@ static const value_string vals_code[] = {
 
 	{ 0, NULL },
 };
-static value_string_ext vals_code_ext = VALUE_STRING_EXT_INIT(vals_code);
+value_string_ext coap_vals_code_ext = VALUE_STRING_EXT_INIT(vals_code);
 
-static const value_string vals_observe_options[] = {
+const value_string coap_vals_observe_options[] = {
 	{ 0, "Register" },
 	{ 1, "Deregister" },
 	{ 0, NULL },
@@ -344,7 +285,7 @@ coap_get_opt_uint(tvbuff_t *tvb, gint offset, gint length)
 }
 
 static gint
-coap_opt_check(packet_info *pinfo, proto_tree *subtree, guint opt_num, gint opt_length)
+coap_opt_check(packet_info *pinfo, proto_tree *subtree, guint opt_num, gint opt_length, coap_common_dissect_t *dissect_hf)
 {
 	int i;
 
@@ -353,12 +294,12 @@ coap_opt_check(packet_info *pinfo, proto_tree *subtree, guint opt_num, gint opt_
 			break;
 	}
 	if (i == (int)(array_length(coi))) {
-		expert_add_info_format(pinfo, subtree, &ei_coap_invalid_option_number,
+		expert_add_info_format(pinfo, subtree, &dissect_hf->ei.opt_invalid_number,
 			"Invalid Option Number %u", opt_num);
 		return -1;
 	}
 	if (opt_length < coi[i].min || opt_length > coi[i].max) {
-		expert_add_info_format(pinfo, subtree, &ei_coap_invalid_option_range,
+		expert_add_info_format(pinfo, subtree, &dissect_hf->ei.opt_invalid_range,
 			"Invalid Option Range: %d (%d < x < %d)", opt_length, coi[i].min, coi[i].max);
 	}
 
@@ -397,11 +338,11 @@ dissect_coap_opt_uint(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree,
 }
 
 static void
-dissect_coap_opt_uri_host(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo)
+dissect_coap_opt_uri_host(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo, int hf)
 {
 	const guint8 *str;
 
-	proto_tree_add_item_ret_string(subtree, hf_coap_opt_uri_host, tvb, offset, opt_length, ENC_ASCII, wmem_packet_scope(), &str);
+	proto_tree_add_item_ret_string(subtree, hf, tvb, offset, opt_length, ENC_ASCII, wmem_packet_scope(), &str);
 
 	/* add info to the head of the packet detail */
 	proto_item_append_text(head_item, ": %s", str);
@@ -418,7 +359,7 @@ dissect_coap_opt_uri_host(tvbuff_t *tvb, proto_item *head_item, proto_tree *subt
 }
 
 static void
-dissect_coap_opt_uri_path(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo)
+dissect_coap_opt_uri_path(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo, int hf)
 {
 	const guint8 *str = NULL;
 
@@ -431,14 +372,14 @@ dissect_coap_opt_uri_path(tvbuff_t *tvb, proto_item *head_item, proto_tree *subt
 		wmem_strbuf_append(coinfo->uri_str_strbuf, str);
 	}
 
-	proto_tree_add_string(subtree, hf_coap_opt_uri_path, tvb, offset, opt_length, str);
+	proto_tree_add_string(subtree, hf, tvb, offset, opt_length, str);
 
 	/* add info to the head of the packet detail */
 	proto_item_append_text(head_item, ": %s", str);
 }
 
 static void
-dissect_coap_opt_uri_query(tvbuff_t *tvb, proto_item *head_item,proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo)
+dissect_coap_opt_uri_query(tvbuff_t *tvb, proto_item *head_item,proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo, int hf)
 {
 	const guint8 *str = NULL;
 
@@ -452,14 +393,14 @@ dissect_coap_opt_uri_query(tvbuff_t *tvb, proto_item *head_item,proto_tree *subt
 		wmem_strbuf_append(coinfo->uri_query_strbuf, str);
 	}
 
-	proto_tree_add_string(subtree, hf_coap_opt_uri_query, tvb, offset, opt_length, str);
+	proto_tree_add_string(subtree, hf, tvb, offset, opt_length, str);
 
 	/* add info to the head of the packet detail */
 	proto_item_append_text(head_item, ": %s", str);
 }
 
 static void
-dissect_coap_opt_location_path(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length)
+dissect_coap_opt_location_path(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, int hf)
 {
 	const guint8 *str = NULL;
 
@@ -469,14 +410,14 @@ dissect_coap_opt_location_path(tvbuff_t *tvb, proto_item *head_item, proto_tree
 		str = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, opt_length, ENC_ASCII);
 	}
 
-	proto_tree_add_string(subtree, hf_coap_opt_location_path, tvb, offset, opt_length, str);
+	proto_tree_add_string(subtree, hf, tvb, offset, opt_length, str);
 
 	/* add info to the head of the packet detail */
 	proto_item_append_text(head_item, ": %s", str);
 }
 
 static void
-dissect_coap_opt_location_query(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length)
+dissect_coap_opt_location_query(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, int hf)
 {
 	const guint8 *str = NULL;
 
@@ -486,7 +427,7 @@ dissect_coap_opt_location_query(tvbuff_t *tvb, proto_item *head_item, proto_tree
 		str = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, opt_length, ENC_ASCII);
 	}
 
-	proto_tree_add_string(subtree, hf_coap_opt_location_query, tvb, offset, opt_length, str);
+	proto_tree_add_string(subtree, hf, tvb, offset, opt_length, str);
 
 	/* add info to the head of the packet detail */
 	proto_item_append_text(head_item, ": %s", str);
@@ -494,7 +435,7 @@ dissect_coap_opt_location_query(tvbuff_t *tvb, proto_item *head_item, proto_tree
 
 /* draft-ietf-core-object-security-07 */
 static void
-dissect_coap_opt_object_security(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, packet_info *pinfo, coap_info *coinfo)
+dissect_coap_opt_object_security(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, packet_info *pinfo, coap_info *coinfo, coap_common_dissect_t *dissect_hf)
 {
 	guint8 flag_byte = 0;
 	gboolean non_compressed = FALSE;
@@ -518,22 +459,22 @@ dissect_coap_opt_object_security(tvbuff_t *tvb, proto_item *head_item, proto_tre
 	} else {
 		flag_byte = tvb_get_guint8(tvb, offset);
 
-		proto_tree_add_item(subtree, hf_coap_opt_object_security_non_compressed, tvb, offset, 1, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_non_compressed, tvb, offset, 1, ENC_BIG_ENDIAN);
 		non_compressed = flag_byte & COAP_OBJECT_SECURITY_NON_COMPRESSED_MASK;
 
-		proto_tree_add_item(subtree, hf_coap_opt_object_security_expand, tvb, offset, 1, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_expand, tvb, offset, 1, ENC_BIG_ENDIAN);
 		expand = flag_byte & COAP_OBJECT_SECURITY_EXPAND_MASK;
 
-		proto_tree_add_item(subtree, hf_coap_opt_object_security_signature, tvb, offset, 1, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_signature, tvb, offset, 1, ENC_BIG_ENDIAN);
 		signature_present = flag_byte & COAP_OBJECT_SECURITY_SIGNATURE_MASK;
 
-		proto_tree_add_item(subtree, hf_coap_opt_object_security_kid_context_present, tvb, offset, 1, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_kid_context_present, tvb, offset, 1, ENC_BIG_ENDIAN);
 		kid_context_present = flag_byte & COAP_OBJECT_SECURITY_KID_CONTEXT_MASK;
 
-		proto_tree_add_item(subtree, hf_coap_opt_object_security_kid_present, tvb, offset, 1, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_kid_present, tvb, offset, 1, ENC_BIG_ENDIAN);
 		kid_present = flag_byte & COAP_OBJECT_SECURITY_KID_MASK;
 
-		proto_tree_add_item(subtree, hf_coap_opt_object_security_piv_len, tvb, offset, 1, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_piv_len, tvb, offset, 1, ENC_BIG_ENDIAN);
 		piv_len = (flag_byte & COAP_OBJECT_SECURITY_PIVLEN_MASK) >> 0;
 
 		/* kid_len is what remains in the option after all other fields are parsed
@@ -545,11 +486,11 @@ dissect_coap_opt_object_security(tvbuff_t *tvb, proto_item *head_item, proto_tre
 
 		if (non_compressed || expand || signature_present) {
 			/* how these bits are handled is not yet specified */
-			expert_add_info_format(pinfo, subtree, &ei_coap_option_object_security_bad, "Unsupported format");
+			expert_add_info_format(pinfo, subtree, &dissect_hf->ei.opt_object_security_bad, "Unsupported format");
 		}
 
 		if (piv_len > 0) {
-			proto_tree_add_item(subtree, hf_coap_opt_object_security_piv, tvb, offset, piv_len, ENC_NA);
+			proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_piv, tvb, offset, piv_len, ENC_NA);
 			coinfo->oscore_info->piv = (guint8 *) tvb_memdup(wmem_packet_scope(), tvb, offset, piv_len);
 			coinfo->oscore_info->piv_len = piv_len;
 
@@ -558,13 +499,13 @@ dissect_coap_opt_object_security(tvbuff_t *tvb, proto_item *head_item, proto_tre
 		}
 
 		if (kid_context_present) {
-			proto_tree_add_item(subtree, hf_coap_opt_object_security_kid_context_len, tvb, offset, 1, ENC_BIG_ENDIAN);
+			proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_kid_context_len, tvb, offset, 1, ENC_BIG_ENDIAN);
 			kid_context_len = tvb_get_guint8(tvb, offset);
 
 			offset += 1;
 			kid_len -= 1;
 
-			proto_tree_add_item(subtree, hf_coap_opt_object_security_kid_context, tvb, offset, kid_context_len, ENC_NA);
+			proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_kid_context, tvb, offset, kid_context_len, ENC_NA);
 			coinfo->oscore_info->kid_context = (guint8 *) tvb_memdup(wmem_packet_scope(), tvb, offset, kid_context_len);
 			coinfo->oscore_info->kid_context_len = kid_context_len;
 
@@ -574,12 +515,12 @@ dissect_coap_opt_object_security(tvbuff_t *tvb, proto_item *head_item, proto_tre
 
 		if (kid_present) {
 			if(kid_len > 0) {
-				proto_tree_add_item(subtree, hf_coap_opt_object_security_kid, tvb, offset, kid_len, ENC_NA);
+				proto_tree_add_item(subtree, dissect_hf->hf.opt_object_security_kid, tvb, offset, kid_len, ENC_NA);
 				coinfo->oscore_info->kid = (guint8 *) tvb_memdup(wmem_packet_scope(), tvb, offset, kid_len);
 				coinfo->oscore_info->kid_len = kid_len;
 
 			} else {
-				expert_add_info_format(pinfo, subtree, &ei_coap_option_object_security_bad, "Key ID flag is set but there are no remaining bytes to be processed");
+				expert_add_info_format(pinfo, subtree, &dissect_hf->ei.opt_object_security_bad, "Key ID flag is set but there are no remaining bytes to be processed");
 			}
 		}
 
@@ -591,7 +532,7 @@ dissect_coap_opt_object_security(tvbuff_t *tvb, proto_item *head_item, proto_tre
 }
 
 static void
-dissect_coap_opt_proxy_uri(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length)
+dissect_coap_opt_proxy_uri(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, int hf)
 {
 	const guint8 *str = NULL;
 
@@ -601,14 +542,14 @@ dissect_coap_opt_proxy_uri(tvbuff_t *tvb, proto_item *head_item, proto_tree *sub
 		str = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, opt_length, ENC_ASCII);
 	}
 
-	proto_tree_add_string(subtree, hf_coap_opt_proxy_uri, tvb, offset, opt_length, str);
+	proto_tree_add_string(subtree, hf, tvb, offset, opt_length, str);
 
 	/* add info to the head of the packet detail */
 	proto_item_append_text(head_item, ": %s", str);
 }
 
 static void
-dissect_coap_opt_proxy_scheme(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length)
+dissect_coap_opt_proxy_scheme(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, int hf)
 {
 	const guint8 *str = NULL;
 
@@ -618,7 +559,7 @@ dissect_coap_opt_proxy_scheme(tvbuff_t *tvb, proto_item *head_item, proto_tree *
 		str = tvb_get_string_enc(wmem_packet_scope(), tvb, offset, opt_length, ENC_ASCII);
 	}
 
-	proto_tree_add_string(subtree, hf_coap_opt_proxy_scheme, tvb, offset, opt_length, str);
+	proto_tree_add_string(subtree, hf, tvb, offset, opt_length, str);
 
 	/* add info to the head of the packet detail */
 	proto_item_append_text(head_item, ": %s", str);
@@ -642,7 +583,7 @@ dissect_coap_opt_ctype(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree
 }
 
 static void
-dissect_coap_opt_block(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo)
+dissect_coap_opt_block(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo, coap_common_dissect_t *dissect_hf)
 {
 	guint8      val = 0;
 	guint       encoded_block_size;
@@ -656,18 +597,18 @@ dissect_coap_opt_block(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree
 		val = tvb_get_guint8(tvb, offset + opt_length - 1) & 0x0f;
 	}
 
-	proto_tree_add_uint(subtree, hf_coap_opt_block_number,
+	proto_tree_add_uint(subtree, dissect_hf->hf.opt_block_number,
 	    tvb, offset, opt_length, coinfo->block_number);
 
 	/* More flag in the end of the option */
 	coinfo->block_mflag = (val & COAP_BLOCK_MFLAG_MASK) >> 3;
-	proto_tree_add_uint(subtree, hf_coap_opt_block_mflag,
+	proto_tree_add_uint(subtree, dissect_hf->hf.opt_block_mflag,
 	    tvb, offset + opt_length - 1, 1, coinfo->block_mflag);
 
 	/* block size */
 	encoded_block_size = val & COAP_BLOCK_SIZE_MASK;
 	block_esize = 1 << (encoded_block_size + 4);
-	proto_tree_add_uint_format(subtree, hf_coap_opt_block_size,
+	proto_tree_add_uint_format(subtree, dissect_hf->hf.opt_block_size,
 	    tvb, offset + opt_length - 1, 1, encoded_block_size, "Block Size: %u (%u encoded)", block_esize, encoded_block_size);
 
 	/* add info to the head of the packet detail */
@@ -676,7 +617,7 @@ dissect_coap_opt_block(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree
 }
 
 static void
-dissect_coap_opt_uri_port(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo)
+dissect_coap_opt_uri_port(tvbuff_t *tvb, proto_item *head_item, proto_tree *subtree, gint offset, gint opt_length, coap_info *coinfo, int hf)
 {
 	guint port = 0;
 
@@ -684,7 +625,7 @@ dissect_coap_opt_uri_port(tvbuff_t *tvb, proto_item *head_item, proto_tree *subt
 		port = coap_get_opt_uint(tvb, offset, opt_length);
 	}
 
-	proto_tree_add_uint(subtree, hf_coap_opt_uri_port, tvb, offset, opt_length, port);
+	proto_tree_add_uint(subtree, hf, tvb, offset, opt_length, port);
 
 	proto_item_append_text(head_item, ": %u", port);
 
@@ -697,7 +638,7 @@ dissect_coap_opt_uri_port(tvbuff_t *tvb, proto_item *head_item, proto_tree *subt
  * return the total length of the option including the header (e.g. delta and length).
  */
 static int
-dissect_coap_options_main(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tree, gint offset, guint8 opt_count, guint *opt_num, gint coap_length, coap_info *coinfo)
+dissect_coap_options_main(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tree, gint offset, guint8 opt_count, guint *opt_num, gint offset_end, coap_info *coinfo, coap_common_dissect_t *dissect_hf)
 {
 	guint8      opt_jump;
 	gint        opt_length, opt_length_ext, opt_delta, opt_delta_ext;
@@ -751,7 +692,7 @@ dissect_coap_options_main(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tr
 		opt_delta += opt_delta_ext;
 		break;
 	case 0xf0:
-		expert_add_info_format(pinfo, coap_tree, &ei_coap_option_length_bad,
+		expert_add_info_format(pinfo, coap_tree, &dissect_hf->ei.opt_length_bad,
 				"end-of-options marker found, but option length isn't 15");
 		return -1;
 	default:
@@ -795,128 +736,128 @@ dissect_coap_options_main(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tr
 		opt_length += opt_length_ext;
 		break;
 	case 0x0f:
-		expert_add_info_format(pinfo, coap_tree, &ei_coap_option_length_bad,
+		expert_add_info_format(pinfo, coap_tree, &dissect_hf->ei.opt_length_bad,
 			"end-of-options marker found, but option delta isn't 15");
 		return -1;
 	default:
 		opt_length = (opt_jump & 0x0f);
 		break;
 	}
-	if (offset + opt_length > coap_length) {
-		expert_add_info_format(pinfo, coap_tree, &ei_coap_option_length_bad,
+	if (opt_length > offset_end - offset) {
+		expert_add_info_format(pinfo, coap_tree, &dissect_hf->ei.opt_length_bad,
 			"option longer than the package");
 		return -1;
 	}
 
-	coap_opt_check(pinfo, coap_tree, *opt_num, opt_length);
+	coap_opt_check(pinfo, coap_tree, *opt_num, opt_length, dissect_hf);
 
 	g_snprintf(strbuf, sizeof(strbuf),
 	    "#%u: %s", opt_count, val_to_str_const(*opt_num, vals_opt_type,
 	    *opt_num % 14 == 0 ? "No-Op" : "Unknown Option"));
-	item = proto_tree_add_string(coap_tree, hf_coap_opt_name,
+	item = proto_tree_add_string(coap_tree, dissect_hf->hf.opt_name,
 	    tvb, orig_offset, offset - orig_offset + opt_length, strbuf);
-	subtree = proto_item_add_subtree(item, ett_coap_option);
+	subtree = proto_item_add_subtree(item, dissect_hf->ett.option);
 
 	g_snprintf(strbuf, sizeof(strbuf),
 	    "Type %u, %s, %s%s", *opt_num,
 	    (*opt_num & 1) ? "Critical" : "Elective",
 	    (*opt_num & 2) ? "Unsafe" : "Safe",
 	    ((*opt_num & 0x1e) == 0x1c) ? ", NoCacheKey" : "");
-	proto_tree_add_string(subtree, hf_coap_opt_desc,
+	proto_tree_add_string(subtree, dissect_hf->hf.opt_desc,
 	    tvb, orig_offset, offset - orig_offset + opt_length, strbuf);
 
-	proto_tree_add_item(subtree, hf_coap_opt_delta,  tvb, orig_offset, 1, ENC_BIG_ENDIAN);
-	proto_tree_add_item(subtree, hf_coap_opt_length, tvb, orig_offset, 1, ENC_BIG_ENDIAN);
+	proto_tree_add_item(subtree, dissect_hf->hf.opt_delta,  tvb, orig_offset, 1, ENC_BIG_ENDIAN);
+	proto_tree_add_item(subtree, dissect_hf->hf.opt_length, tvb, orig_offset, 1, ENC_BIG_ENDIAN);
 
 	if (opt_delta_ext_off && opt_delta_ext_len)
-		proto_tree_add_item(subtree, hf_coap_opt_delta_ext, tvb, opt_delta_ext_off, opt_delta_ext_len, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_delta_ext, tvb, opt_delta_ext_off, opt_delta_ext_len, ENC_BIG_ENDIAN);
 
 	if (opt_length_ext_off && opt_length_ext_len)
-		proto_tree_add_item(subtree, hf_coap_opt_length_ext, tvb, opt_length_ext_off, opt_length_ext_len, ENC_BIG_ENDIAN);
+		proto_tree_add_item(subtree, dissect_hf->hf.opt_length_ext, tvb, opt_length_ext_off, opt_length_ext_len, ENC_BIG_ENDIAN);
 
 	/* offset points the next to its option header */
 	switch (*opt_num) {
 	case COAP_OPT_CONTENT_TYPE:
 		dissect_coap_opt_ctype(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_ctype, coinfo);
+		    opt_length, dissect_hf->hf.opt_ctype, coinfo);
 		break;
 	case COAP_OPT_MAX_AGE:
 		dissect_coap_opt_uint(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_max_age);
+		    opt_length, dissect_hf->hf.opt_max_age);
 		break;
 	case COAP_OPT_PROXY_URI:
 		dissect_coap_opt_proxy_uri(tvb, item, subtree, offset,
-		    opt_length);
+		    opt_length, dissect_hf->hf.opt_proxy_uri);
 		break;
 	case COAP_OPT_PROXY_SCHEME:
 		dissect_coap_opt_proxy_scheme(tvb, item, subtree, offset,
-		    opt_length);
+		    opt_length, dissect_hf->hf.opt_proxy_scheme);
 		break;
 	case COAP_OPT_SIZE1:
 		dissect_coap_opt_uint(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_size1);
+		    opt_length, dissect_hf->hf.opt_size1);
 		break;
 	case COAP_OPT_ETAG:
 		dissect_coap_opt_hex_string(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_etag);
+		    opt_length, dissect_hf->hf.opt_etag);
 		break;
 	case COAP_OPT_URI_HOST:
 		dissect_coap_opt_uri_host(tvb, item, subtree, offset,
-		    opt_length, coinfo);
+		    opt_length, coinfo, dissect_hf->hf.opt_uri_host);
 		break;
 	case COAP_OPT_LOCATION_PATH:
 		dissect_coap_opt_location_path(tvb, item, subtree, offset,
-		    opt_length);
+		    opt_length, dissect_hf->hf.opt_location_path);
 		break;
 	case COAP_OPT_URI_PORT:
 		dissect_coap_opt_uri_port(tvb, item, subtree, offset,
-		    opt_length, coinfo);
+		    opt_length, coinfo, dissect_hf->hf.opt_uri_port);
 		break;
 	case COAP_OPT_LOCATION_QUERY:
 		dissect_coap_opt_location_query(tvb, item, subtree, offset,
-		    opt_length);
+		    opt_length, dissect_hf->hf.opt_location_query);
 		break;
 	case COAP_OPT_OBJECT_SECURITY:
 		dissect_coap_opt_object_security(tvb, item, subtree, offset,
-		    opt_length, pinfo, coinfo);
+		    opt_length, pinfo, coinfo, dissect_hf);
 		break;
 	case COAP_OPT_URI_PATH:
 		dissect_coap_opt_uri_path(tvb, item, subtree, offset,
-		    opt_length, coinfo);
+		    opt_length, coinfo, dissect_hf->hf.opt_uri_path);
 		break;
 	case COAP_OPT_OBSERVE:
 		dissect_coap_opt_uint(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_observe);
+		    opt_length, dissect_hf->hf.opt_observe);
 		break;
 	case COAP_OPT_ACCEPT:
 		dissect_coap_opt_ctype(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_accept, coinfo);
+		    opt_length, dissect_hf->hf.opt_accept, coinfo);
 		break;
 	case COAP_OPT_IF_MATCH:
 		dissect_coap_opt_hex_string(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_if_match);
+		    opt_length, dissect_hf->hf.opt_if_match);
 		break;
 	case COAP_OPT_URI_QUERY:
 		dissect_coap_opt_uri_query(tvb, item, subtree, offset,
-		    opt_length, coinfo);
+		    opt_length, coinfo, dissect_hf->hf.opt_uri_query);
 		break;
 	case COAP_OPT_BLOCK2:
 		dissect_coap_opt_block(tvb, item, subtree, offset,
-		    opt_length, coinfo);
+		    opt_length, coinfo, dissect_hf);
 		break;
 	case COAP_OPT_BLOCK1:
 		dissect_coap_opt_block(tvb, item, subtree, offset,
-		    opt_length, coinfo);
+		    opt_length, coinfo, dissect_hf);
 		break;
 	case COAP_OPT_IF_NONE_MATCH:
 		break;
 	case COAP_OPT_BLOCK_SIZE:
 		dissect_coap_opt_uint(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_block_size);
+		    opt_length, dissect_hf->hf.opt_block_size);
 		break;
 	default:
 		dissect_coap_opt_hex_string(tvb, item, subtree, offset,
-		    opt_length, hf_coap_opt_unknown);
+		    opt_length, dissect_hf->hf.opt_unknown);
 		break;
 	}
 
@@ -928,24 +869,24 @@ dissect_coap_options_main(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tr
  * return offset pointing the next of options. (i.e. the top of the paylaod
  * or the end of the data.
  */
-static int
-dissect_coap_options(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tree, gint offset, gint coap_length, coap_info *coinfo)
+int
+dissect_coap_options(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tree, gint offset, gint offset_end, coap_info *coinfo, coap_common_dissect_t *dissect_hf)
 {
 	guint  opt_num = 0;
 	int    i;
 	guint8 endmarker;
 
 	/* loop for dissecting options */
-	for (i = 1; offset < coap_length; i++) {
+	for (i = 1; offset < offset_end; i++) {
 		offset = dissect_coap_options_main(tvb, pinfo, coap_tree,
-		    offset, i, &opt_num, coap_length, coinfo);
+		    offset, i, &opt_num, offset_end, coinfo, dissect_hf);
 		if (offset == -1)
 			return -1;
-		if (offset >= coap_length)
+		if (offset >= offset_end)
 			break;
 		endmarker = tvb_get_guint8(tvb, offset);
 		if (endmarker == 0xff) {
-			proto_tree_add_item(coap_tree, hf_coap_opt_end_marker, tvb, offset, 1, ENC_BIG_ENDIAN);
+			proto_tree_add_item(coap_tree, dissect_hf->hf.opt_end_marker, tvb, offset, 1, ENC_BIG_ENDIAN);
 			offset += 1;
 			break;
 		}
@@ -954,6 +895,87 @@ dissect_coap_options(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tree, g
 	return offset;
 }
 
+/*
+ * CoAP code dissector.
+ * return code value and updates the offset
+ * */
+guint8
+dissect_coap_code(tvbuff_t *tvb, proto_tree *tree, gint *offset, coap_common_dissect_t *dissect_hf, guint8 *code_class)
+{
+	guint8 code;
+
+	proto_tree_add_item(tree, dissect_hf->hf.code, tvb, *offset, 1, ENC_BIG_ENDIAN);
+	code = tvb_get_guint8(tvb, *offset);
+	*code_class = code >> 5;
+	*offset += 1;
+
+	return code;
+}
+
+void
+dissect_coap_payload(tvbuff_t *tvb, packet_info *pinfo, proto_tree *coap_tree, proto_tree *parent_tree, gint offset, gint offset_end, guint8 code_class, coap_info *coinfo, coap_common_dissect_t *dissect_hf, gboolean oscore)
+{
+	proto_tree *payload_tree;
+	proto_item *payload_item, *length_item;
+	tvbuff_t   *payload_tvb;
+	guint	    payload_length = offset_end - offset;
+	const char *coap_ctype_str_dis;
+	char	    str_payload[80];
+
+	/* coinfo->ctype_value == DEFAULT_COAP_CTYPE_VALUE: No Content-Format option present */
+	if (coinfo->ctype_value == DEFAULT_COAP_CTYPE_VALUE) {
+		/*
+		* 5.5.2.  Diagnostic Payload
+		*
+		* If no Content-Format option is given, the payload of responses
+		* indicating a client or server error is a brief human-readable
+		* diagnostic message, explaining the error situation. This diagnostic
+		* message MUST be encoded using UTF-8 [RFC3629], more specifically
+		* using Net-Unicode form [RFC5198].
+		*/
+		if ((code_class >= 4) && (code_class <= 5)) {
+			coinfo->ctype_str = "text/plain; charset=utf-8";
+			coap_ctype_str_dis = "text/plain";
+		} else {
+			/* Assume no Content-Format is opaque octet stream */
+			coinfo->ctype_str = "application/octet-stream";
+			coap_ctype_str_dis = coinfo->ctype_str;
+		}
+	}
+	/* coinfo->ctype_value == 0: Content-Format option present with length 0 */
+	else if (coinfo->ctype_value == 0) {
+		/* coinfo->ctype_str is already set by option parsing routine */
+		coap_ctype_str_dis = "text/plain";
+	} else {
+		coap_ctype_str_dis = coinfo->ctype_str;
+	}
+
+	g_snprintf(str_payload, sizeof(str_payload),
+			"Payload Content-Format: %s%s, Length: %u",
+			coinfo->ctype_str, coinfo->ctype_value == DEFAULT_COAP_CTYPE_VALUE ?
+			" (no Content-Format)" : "", payload_length);
+
+	payload_item = proto_tree_add_string(coap_tree, dissect_hf->hf.payload,
+					     tvb, offset, payload_length,
+					     str_payload);
+	payload_tree = proto_item_add_subtree(payload_item, dissect_hf->ett.payload);
+
+	proto_tree_add_string(payload_tree, dissect_hf->hf.payload_desc, tvb, offset, 0, coinfo->ctype_str);
+	length_item = proto_tree_add_uint(payload_tree, dissect_hf->hf.payload_length, tvb, offset, 0, payload_length);
+	PROTO_ITEM_SET_GENERATED(length_item);
+	payload_tvb = tvb_new_subset_length(tvb, offset, payload_length);
+
+	dissector_try_string(media_type_dissector_table, coap_ctype_str_dis,
+			     payload_tvb, pinfo, parent_tree, NULL);
+
+	if (coinfo->object_security && !oscore) {
+		/* Indicate to OSCORE if this is a response */
+		coinfo->oscore_info->response = ((code_class >= 2) && (code_class <= 5));
+		proto_item_set_text(payload_item, "Encrypted OSCORE Data");
+		call_dissector_with_data(oscore_handle, payload_tvb, pinfo, parent_tree, coinfo->oscore_info);
+	}
+}
+
 static int
 dissect_coap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* data _U_)
 {
@@ -1007,10 +1029,7 @@ dissect_coap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* d
 
 	offset += 1;
 
-	proto_tree_add_item(coap_tree, hf_coap_code, tvb, offset, 1, ENC_BIG_ENDIAN);
-	code = tvb_get_guint8(tvb, offset);
-	code_class = code >> 5;
-	offset += 1;
+	code = dissect_coap_code(tvb, coap_tree, &offset, &dissect_coap_hf, &code_class);
 
 	proto_tree_add_item(coap_tree, hf_coap_mid, tvb, offset, 2, ENC_BIG_ENDIAN);
 	mid = tvb_get_ntohs(tvb, offset);
@@ -1019,13 +1038,13 @@ dissect_coap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* d
 		     "%s, MID:%u, %s",
 		     val_to_str(ttype, vals_ttype_short, "Unknown %u"),
 		     mid,
-		     val_to_str_ext(code, &vals_code_ext, "Unknown %u"));
+		     val_to_str_ext(code, &coap_vals_code_ext, "Unknown %u"));
 
 	/* append the header information */
 	proto_item_append_text(coap_root,
 			       ", %s, %s, MID:%u",
 			       val_to_str(ttype, vals_ttype, "Unknown %u"),
-			       val_to_str_ext(code, &vals_code_ext, "Unknown %u"),
+			       val_to_str_ext(code, &coap_vals_code_ext, "Unknown %u"),
 			       mid);
 
 	offset += 2;
@@ -1051,7 +1070,7 @@ dissect_coap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* d
 	}
 
 	/* process options */
-	offset = dissect_coap_options(tvb, pinfo, coap_tree, offset, coap_length, coinfo);
+	offset = dissect_coap_options(tvb, pinfo, coap_tree, offset, coap_length, coinfo, &dissect_coap_hf);
 	if (offset == -1)
 		return tvb_captured_length(tvb);
 
@@ -1177,7 +1196,7 @@ dissect_coap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* d
 	if (wmem_strbuf_get_len(coinfo->uri_str_strbuf) > 0) {
 		col_append_fstr(pinfo->cinfo, COL_INFO, ", %s", wmem_strbuf_get_str(coinfo->uri_str_strbuf));
 		/* Add a generated protocol item as well */
-		pi = proto_tree_add_string(coap_tree, hf_coap_opt_uri_path_recon, tvb, 0, 0, wmem_strbuf_get_str(coinfo->uri_str_strbuf));
+		pi = proto_tree_add_string(coap_tree, dissect_coap_hf.hf.opt_uri_path_recon, tvb, 0, 0, wmem_strbuf_get_str(coinfo->uri_str_strbuf));
 		PROTO_ITEM_SET_GENERATED(pi);
 	}
 	if (wmem_strbuf_get_len(coinfo->uri_query_strbuf) > 0)
@@ -1185,60 +1204,7 @@ dissect_coap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void* d
 
 	/* dissect the payload */
 	if (coap_length > offset) {
-		proto_tree *payload_tree;
-		proto_item *payload_item, *length_item;
-		tvbuff_t   *payload_tvb;
-		guint	    payload_length = coap_length - offset;
-		const char *coap_ctype_str_dis;
-		char	    str_payload[80];
-
-		/* coinfo->ctype_value == DEFAULT_COAP_CTYPE_VALUE: No Content-Format option present */
-		/* coinfo->ctype_value == 0: Content-Format option present with length 0 */
-		if (coinfo->ctype_value == DEFAULT_COAP_CTYPE_VALUE || coinfo->ctype_value == 0) {
-			/*
-			* 5.5.2.  Diagnostic Payload
-			*
-			* If no Content-Format option is given, the payload of responses
-			* indicating a client or server error is a brief human-readable
-			* diagnostic message, explaining the error situation. This diagnostic
-			* message MUST be encoded using UTF-8 [RFC3629], more specifically
-			* using Net-Unicode form [RFC5198].
-			*/
-			if ((code_class >= 4) && (code_class <= 5)) {
-				coinfo->ctype_str = "text/plain; charset=utf-8";
-				coap_ctype_str_dis = "text/plain";
-			} else {
-				/* Assume no Content-Format is opaque octet stream */
-				coinfo->ctype_str = "application/octet-stream";
-				coap_ctype_str_dis = coinfo->ctype_str;
-			}
-		} else {
-			coap_ctype_str_dis = coinfo->ctype_str;
-		}
-		g_snprintf(str_payload, sizeof(str_payload),
-				"Payload Content-Format: %s%s, Length: %u",
-				coinfo->ctype_str, coinfo->ctype_value == DEFAULT_COAP_CTYPE_VALUE ?
-				" (no Content-Format)" : "", payload_length);
-
-		payload_item = proto_tree_add_string(coap_tree, hf_coap_payload,
-						     tvb, offset, payload_length,
-						     str_payload);
-		payload_tree = proto_item_add_subtree(payload_item, ett_coap_payload);
-
-		proto_tree_add_string(payload_tree, hf_coap_payload_desc, tvb, offset, 0, coinfo->ctype_str);
-		length_item = proto_tree_add_uint(payload_tree, hf_coap_payload_length, tvb, offset, 0, payload_length);
-		PROTO_ITEM_SET_GENERATED(length_item);
-		payload_tvb = tvb_new_subset_length(tvb, offset, payload_length);
-
-		dissector_try_string(media_type_dissector_table, coap_ctype_str_dis,
-				     payload_tvb, pinfo, parent_tree, NULL);
-
-		if (coinfo->object_security) {
-			/* Indicate to OSCORE if this is a response */
-			coinfo->oscore_info->response = ((code_class >= 2) && (code_class <= 5)) ? TRUE : FALSE;
-			proto_item_set_text(payload_item, "Encrypted OSCORE Data");
-			call_dissector_with_data(oscore_handle, payload_tvb, pinfo, parent_tree, coinfo->oscore_info);
-		}
+		dissect_coap_payload(tvb, pinfo, coap_tree, parent_tree, offset, coap_length, code_class, coinfo, &dissect_coap_hf, FALSE);
 	}
 
 	return tvb_captured_length(tvb);
@@ -1271,216 +1237,11 @@ proto_register_coap(void)
 		    FT_BYTES, BASE_NONE, NULL, 0x0,
 		    NULL, HFILL }
 		},
-		{ &hf_coap_code,
-		  { "Code", "coap.code",
-		    FT_UINT8, BASE_DEC | BASE_EXT_STRING, &vals_code_ext, 0x0,
-		    NULL, HFILL }
-		},
 		{ &hf_coap_mid,
 		  { "Message ID", "coap.mid",
 		    FT_UINT16, BASE_DEC, NULL, 0x0,
 		    NULL, HFILL }
 		},
-		{ &hf_coap_payload,
-		  { "Payload", "coap.payload",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_payload_desc,
-		  { "Payload Desc", "coap.payload_desc",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_payload_length,
-		    { "Payload Length", "coap.payload_length",
-		    FT_UINT32, BASE_DEC, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_name,
-		  { "Opt Name", "coap.opt.name",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_desc,
-		  { "Opt Desc", "coap.opt.desc",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_delta,
-		  { "Opt Delta", "coap.opt.delta",
-		    FT_UINT8, BASE_DEC, NULL, 0xf0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_delta_ext,
-		  { "Opt Delta extended", "coap.opt.delta_ext",
-		    FT_UINT16, BASE_DEC, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_length,
-		  { "Opt Length", "coap.opt.length",
-		    FT_UINT8, BASE_DEC, NULL, 0x0f,
-		    "CoAP Option Length", HFILL }
-		},
-		{ &hf_coap_opt_length_ext,
-		  { "Opt Length extended", "coap.opt.length_ext",
-		    FT_UINT16, BASE_DEC, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_end_marker,
-		  { "End of options marker", "coap.opt.end_marker",
-		    FT_UINT8, BASE_DEC, NULL, 0x00,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_ctype,
-		  { "Content-type", "coap.opt.ctype",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_max_age,
-		  { "Max-age", "coap.opt.max_age",
-		    FT_UINT32, BASE_DEC, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_proxy_uri,
-		  { "Proxy-Uri", "coap.opt.proxy_uri",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_proxy_scheme,
-		  { "Proxy-Scheme", "coap.opt.proxy_scheme",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_size1,
-		  { "Size1", "coap.opt.size1",
-		    FT_UINT32, BASE_DEC, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_etag,
-		  { "Etag", "coap.opt.etag",
-		    FT_BYTES, BASE_NONE, NULL, 0x0,
-		    "CoAP Option Etag", HFILL }
-		},
-		{ &hf_coap_opt_uri_host,
-		  { "Uri-Host", "coap.opt.uri_host",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_location_path,
-		  { "Location-Path", "coap.opt.location_path",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_uri_port,
-		  { "Uri-Port", "coap.opt.uri_port",
-		    FT_UINT16, BASE_DEC, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_location_query,
-		  { "Location-Query", "coap.opt.location_query",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_non_compressed,
-		  { "Non-compressed COSE message", "coap.opt.object_security_non_compressed",
-		    FT_BOOLEAN, 8, NULL, COAP_OBJECT_SECURITY_NON_COMPRESSED_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_expand,
-		  { "Expanded Flag Byte", "coap.opt.object_security_expand",
-		    FT_BOOLEAN, 8, NULL, COAP_OBJECT_SECURITY_EXPAND_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_signature,
-		  { "Signature Present", "coap.opt.object_security_signature",
-		    FT_BOOLEAN, 8, NULL, COAP_OBJECT_SECURITY_SIGNATURE_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_kid_context_present,
-		  { "Key ID Context Present", "coap.opt.object_security_kid_context_present",
-		    FT_BOOLEAN, 8, NULL, COAP_OBJECT_SECURITY_KID_CONTEXT_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_kid_present,
-		  { "Key ID Present", "coap.opt.object_security_kid",
-		    FT_BOOLEAN, 8, NULL, COAP_OBJECT_SECURITY_KID_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_piv_len,
-		  { "Partial IV Length", "coap.opt.object_security_piv_len",
-		    FT_UINT8, BASE_DEC, NULL, COAP_OBJECT_SECURITY_PIVLEN_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_piv,
-		  { "Partial IV", "coap.opt.object_security_piv",
-		    FT_BYTES, BASE_NONE, NULL, 0x00,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_kid_context_len,
-		  { "Key ID Context Length", "coap.opt.object_security_kid_context_len",
-		    FT_UINT8, BASE_DEC, NULL, 0x00,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_kid_context,
-		  { "Partial IV", "coap.opt.object_security_kid_context",
-		    FT_BYTES, BASE_NONE, NULL, 0x00,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_object_security_kid,
-		  { "Key ID", "coap.opt.object_security_kid",
-		    FT_BYTES, BASE_NONE, NULL, 0x00,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_uri_path,
-		  { "Uri-Path", "coap.opt.uri_path",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_uri_path_recon,
-		  { "Uri-Path", "coap.opt.uri_path_recon",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_observe,
-		  { "Observe", "coap.opt.observe",
-		    FT_UINT32, BASE_DEC, VALS(vals_observe_options), 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_accept,
-		  { "Accept", "coap.opt.accept",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_if_match,
-		  { "If-Match", "coap.opt.if_match",
-		    FT_BYTES, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_block_number,
-		  { "Block Number", "coap.opt.block_number",
-		    FT_UINT32, BASE_DEC, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_block_mflag,
-		  { "More Flag", "coap.opt.block_mflag",
-		    FT_UINT8, BASE_DEC, NULL, COAP_BLOCK_MFLAG_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_block_size,
-		  { "Encoded Block Size", "coap.opt.block_size",
-		    FT_UINT8, BASE_DEC, NULL, COAP_BLOCK_SIZE_MASK,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_uri_query,
-		  { "Uri-Query", "coap.opt.uri_query",
-		    FT_STRING, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
-		{ &hf_coap_opt_unknown,
-		  { "Unknown", "coap.opt.unknown",
-		    FT_BYTES, BASE_NONE, NULL, 0x0,
-		    NULL, HFILL }
-		},
 		{ &hf_coap_response_in,
 		  { "Response In", "coap.response_in",
 		    FT_FRAMENUM, BASE_NONE, NULL, 0x0,
@@ -1508,24 +1269,16 @@ proto_register_coap(void)
 		  { "OSCORE Partial IV", "coap.oscore_piv", FT_BYTES, BASE_NONE, NULL, 0x0,
 		    "Matched OSCORE Partial IV", HFILL }
 		},
+		COAP_COMMON_HF_LIST(dissect_coap_hf, "coap")
 	};
 
 	static gint *ett[] = {
 		&ett_coap,
-		&ett_coap_option,
-		&ett_coap_payload,
+		COAP_COMMON_ETT_LIST(dissect_coap_hf)
 	};
 
 	static ei_register_info ei[] = {
-		{ &ei_coap_invalid_option_number,
-		  { "coap.invalid_option_number", PI_MALFORMED, PI_WARN, "Invalid Option Number", EXPFILL }},
-		{ &ei_coap_invalid_option_range,
-		  { "coap.invalid_option_range", PI_MALFORMED, PI_WARN, "Invalid Option Range", EXPFILL }},
-		{ &ei_coap_option_length_bad,
-		  { "coap.option_length_bad", PI_MALFORMED, PI_WARN, "Option length bad", EXPFILL }},
-		{ &ei_coap_option_object_security_bad,
-		  { "coap.option.object_security", PI_MALFORMED, PI_WARN, "Invalid Object-Security Option Format", EXPFILL }},
-
+		COAP_COMMON_EI_LIST(dissect_coap_hf, "coap")
 	};
 
 	expert_module_t *expert_coap;