SAToP: Add optional RTP header handling
This commit is contained in:
Jaap Keuter
Alexis La Goutte
parent
46a7f4c17f
commit
c38e6ecbf6
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@ -14,7 +14,6 @@
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* 14.08.2009 added: support for IP/UDP demultiplexing
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* Not supported yet:
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* - Decoding of PW payload
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* - Optional RTP Headers (RFC3550)
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*/
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#include "config.h"
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@ -24,6 +23,9 @@
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#include "packet-mpls.h"
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#include "packet-pw-common.h"
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#include "packet-rtp.h"
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#define SIZEOF_RTP 12
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void proto_register_pw_satop(void);
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void proto_reg_handoff_pw_satop(void);
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@ -53,9 +55,12 @@ static dissector_handle_t pw_padding_handle;
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static dissector_handle_t pw_satop_udp_handle;
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static dissector_handle_t pw_satop_mpls_handle;
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const char pwc_longname_pw_satop[] = "SAToP";
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static const char shortname[] = "SAToP";
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const char pwc_longname_pw_satop[] = "SAToP (no RTP support)";
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static const char shortname[] = "SAToP (no RTP)";
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/* Preferences */
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static gboolean pref_has_rtp_header = FALSE;
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static gboolean pref_heuristic_rtp_header = TRUE;
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static
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@ -64,11 +69,16 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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,proto_tree * tree
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,pwc_demux_type_t demux)
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{
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const int encaps_size = 4; /*RTP header in encapsulation is not supported yet*/
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int min_packet_size_this_dissector = PWC_SIZEOF_CW;
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int encaps_size;
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gint packet_size;
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gint rtp_header_offset;
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gint cw_offset;
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gint payload_size;
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gint padding_size;
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int properties;
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guint16 sn;
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gboolean has_rtp_header;
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enum {
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PAY_NO_IDEA = 0
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@ -78,24 +88,6 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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,PAY_LIKE_OCTET_ALIGNED_T1
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} payload_properties;
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packet_size = tvb_reported_length_remaining(tvb_original, 0);
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/*
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* FIXME
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* "4" below should be replaced by something like "min_packet_size_this_dissector"
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* Also call to dissect_try_cw_first_nibble() should be moved before this block
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*/
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if (packet_size < 4) /* 4 is smallest size which may be sensible (for PWACH dissector) */
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{
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proto_item *item;
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item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
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expert_add_info_format(pinfo, item, &ei_cw_packet_size_too_small,
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"PW packet size (%d) is too small to carry sensible information"
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,(int)packet_size);
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col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
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col_set_str(pinfo->cinfo, COL_INFO, "Malformed: PW packet is too small");
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return;
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}
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switch (demux)
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{
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case PWC_DEMUX_MPLS:
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@ -111,18 +103,79 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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return;
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}
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packet_size = tvb_reported_length_remaining(tvb_original, 0);
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if (pref_has_rtp_header) {
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min_packet_size_this_dissector += SIZEOF_RTP;
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}
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if (packet_size < min_packet_size_this_dissector)
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{
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proto_item *item;
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item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
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expert_add_info_format(pinfo, item, &ei_cw_packet_size_too_small,
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"PW packet size (%d) is too small to carry sensible information"
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,(int)packet_size);
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col_set_str(pinfo->cinfo, COL_PROTOCOL, shortname);
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col_set_str(pinfo->cinfo, COL_INFO, "Malformed: PW packet is too small");
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return;
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}
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switch (demux)
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{
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case PWC_DEMUX_MPLS:
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rtp_header_offset = PWC_SIZEOF_CW;
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sn = tvb_get_guint16(tvb_original, 2, ENC_BIG_ENDIAN);
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break;
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case PWC_DEMUX_UDP:
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rtp_header_offset = 0;
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sn = tvb_get_guint16(tvb_original, SIZEOF_RTP + 2, ENC_BIG_ENDIAN);
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break;
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default:
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DISSECTOR_ASSERT_NOT_REACHED();
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return;
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}
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if ((pref_has_rtp_header) ||
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((pref_heuristic_rtp_header) &&
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/* Check for RTP version 2, the other fields must be zero */
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(tvb_get_guint8(tvb_original, rtp_header_offset) == 0x80) &&
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/* Check the marker is zero. Unfortnately PT is not always from the dynamic range */
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((tvb_get_guint8(tvb_original, rtp_header_offset + 1) & 0x80) == 0) &&
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/* The sequence numbers from cw and RTP header must match */
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(tvb_get_ntohs(tvb_original, rtp_header_offset + 2) == sn)))
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{
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switch (demux)
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{
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case PWC_DEMUX_MPLS:
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cw_offset = 0;
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break;
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case PWC_DEMUX_UDP:
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cw_offset = SIZEOF_RTP;
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break;
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default:
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DISSECTOR_ASSERT_NOT_REACHED();
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return;
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}
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encaps_size = PWC_SIZEOF_CW + SIZEOF_RTP;
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has_rtp_header = TRUE;
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} else {
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cw_offset = 0;
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encaps_size = PWC_SIZEOF_CW;
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has_rtp_header = FALSE;
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}
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/* check how "good" is this packet */
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/* also decide payload length from packet size and CW */
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/* also decide payload length from packet size, CW and optional RTP header */
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properties = 0;
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if (0 != (tvb_get_guint8(tvb_original, 0) & 0xf0 /*bits03*/))
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if (0 != (tvb_get_guint8(tvb_original, cw_offset) & 0xf0 /*bits03*/))
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{
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properties |= PWC_CW_BAD_BITS03;
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}
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if (0 != (tvb_get_guint8(tvb_original, 0) & 0x03 /*rsv*/))
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if (0 != (tvb_get_guint8(tvb_original, cw_offset) & 0x03 /*rsv*/))
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{
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properties |= PWC_CW_BAD_RSV;
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}
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if (0 != (tvb_get_guint8(tvb_original, 1) & 0xc0 /*frag*/))
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if (0 != (tvb_get_guint8(tvb_original, cw_offset + 1) & 0xc0 /*frag*/))
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{
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properties |= PWC_CW_BAD_FRAG;
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}
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@ -142,7 +195,7 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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int cw_len;
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gint payload_size_from_packet;
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cw_len = tvb_get_guint8(tvb_original, 1) & 0x3f;
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cw_len = tvb_get_guint8(tvb_original, cw_offset + 1) & 0x3f;
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payload_size_from_packet = packet_size - encaps_size;
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if (cw_len != 0)
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{
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@ -186,7 +239,7 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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* not blame packets with bad payload (including "bad" or "strange" SIZE of
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* payload) when L bit is set.
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*/
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if (0 == (tvb_get_guint8(tvb_original, 0) & 0x08 /*L bit*/))
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if (0 == (tvb_get_guint8(tvb_original, cw_offset) & 0x08 /*L bit*/))
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{
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properties |= PWC_PAY_SIZE_BAD;
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}
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@ -240,17 +293,22 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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{
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proto_item* item;
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item = proto_tree_add_item(tree, proto, tvb_original, 0, -1, ENC_NA);
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pwc_item_append_cw(item,tvb_get_ntohl(tvb_original, 0),TRUE);
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pwc_item_append_text_n_items(item,(int)payload_size,"octet");
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pwc_item_append_cw(item, tvb_get_ntohl(tvb_original, cw_offset), TRUE);
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pwc_item_append_text_n_items(item, (int)payload_size, "octet");
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{
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proto_tree* tree2;
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tree2 = proto_item_add_subtree(item, ett_pw_satop);
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if (has_rtp_header && demux == PWC_DEMUX_UDP)
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{
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dissect_rtp_shim_header(tvb_original, 0, pinfo, tree2, NULL);
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}
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{
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tvbuff_t* tvb;
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proto_item* item2;
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tvb = tvb_new_subset_length(tvb_original, 0, PWC_SIZEOF_CW);
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tvb = tvb_new_subset_length(tvb_original, cw_offset, PWC_SIZEOF_CW);
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item2 = proto_tree_add_item(tree2, hf_cw, tvb, 0, -1, ENC_NA);
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pwc_item_append_cw(item2, tvb_get_ntohl(tvb, 0),FALSE);
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pwc_item_append_cw(item2, tvb_get_ntohl(tvb, 0), FALSE);
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{
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proto_tree* tree3;
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tree3 = proto_item_add_subtree(item2, ett_pw_satop);
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@ -262,8 +320,8 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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expert_add_info(pinfo, item3, &ei_cw_bits03);
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}
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proto_tree_add_item(tree3, hf_cw_l , tvb, 0, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(tree3, hf_cw_r , tvb, 0, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(tree3, hf_cw_l, tvb, 0, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(tree3, hf_cw_r, tvb, 0, 1, ENC_BIG_ENDIAN);
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item3 = proto_tree_add_item(tree3, hf_cw_rsv, tvb, 0, 1, ENC_BIG_ENDIAN);
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if (properties & PWC_CW_BAD_RSV)
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@ -301,6 +359,11 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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}
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}
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}
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if (has_rtp_header && demux != PWC_DEMUX_UDP)
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{
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dissect_rtp_shim_header(tvb_original, PWC_SIZEOF_CW, pinfo, tree2, NULL);
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}
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}
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/* payload */
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@ -321,9 +384,9 @@ void dissect_pw_satop(tvbuff_t * tvb_original
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{
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proto_item* item2;
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tvbuff_t* tvb;
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tvb = tvb_new_subset_length(tvb_original, PWC_SIZEOF_CW, payload_size);
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tvb = tvb_new_subset_length(tvb_original, encaps_size, payload_size);
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item2 = proto_tree_add_item(tree2, hf_payload, tvb, 0, -1, ENC_NA);
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pwc_item_append_text_n_items(item2,(int)payload_size,"octet");
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pwc_item_append_text_n_items(item2, (int)payload_size, "octet");
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{
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proto_tree* tree3;
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const char* s;
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@ -443,6 +506,8 @@ void proto_register_pw_satop(void)
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{ &ei_payload_size_invalid, { "pwsatop.payload.size_invalid", PI_MALFORMED, PI_ERROR, "Bad Length: too small", EXPFILL }},
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{ &ei_payload_size_invalid_undecoded, { "pwsatop.payload.undecoded", PI_UNDECODED, PI_NOTE, "SAToP payload: omitted to conserve bandwidth", EXPFILL }},
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};
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module_t *pwsatop_module;
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expert_module_t* expert_pwsatop;
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proto = proto_register_protocol(pwc_longname_pw_satop, shortname, "pwsatopcw");
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@ -450,6 +515,11 @@ void proto_register_pw_satop(void)
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proto_register_subtree_array(ett_array, array_length(ett_array));
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expert_pwsatop = expert_register_protocol(proto);
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expert_register_field_array(expert_pwsatop, ei, array_length(ei));
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pwsatop_module = prefs_register_protocol(proto, NULL);
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prefs_register_bool_preference(pwsatop_module, "rtp_header", "RTP header in SAToP header",
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"Whether or not the RTP header is present in the SAToP header.", &pref_has_rtp_header);
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prefs_register_bool_preference(pwsatop_module, "rtp_header_heuristic", "Try to find RTP header in SAToP header",
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"Heuristically determine if an RTP header is present in the SAToP header.", &pref_heuristic_rtp_header);
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pw_satop_mpls_handle = register_dissector("pw_satop_mpls", dissect_pw_satop_mpls, proto);
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pw_satop_udp_handle = register_dissector("pw_satop_udp", dissect_pw_satop_udp, proto);
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}
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