Add code to dissect "original uTP header format"
as described in the LibuTP utp.cpp source code; Add a kludgy heuristic to differentiate between original and "V1" header formats. TBD: validity of the heuristic; is there a better way ? svn path=/trunk/; revision=36742
This commit is contained in:
Bill Meier
parent
c590fd1d73
commit
2eced546c1
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@ -31,21 +31,34 @@
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#define DEFAULT_UDP_PORT 55627
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enum {
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ST_DATA = 0,
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ST_FIN = 1,
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ST_STATE = 2,
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ST_RESET = 3,
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ST_SYN = 4,
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ST_NUM_STATES,
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};
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/* V0 hdr: "flags"; V1 hdr: "type" */
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static const value_string bt_utp_type_vals[] = {
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{ 0, "Data" },
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{ 1, "Fin" },
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{ 2, "State" },
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{ 3, "Reset" },
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{ 4, "Syn" },
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{ ST_DATA, "Data" },
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{ ST_FIN, "Fin" },
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{ ST_STATE, "State" },
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{ ST_RESET, "Reset" },
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{ ST_SYN, "Syn" },
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{ 0, NULL }
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};
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#define EXT_NO_EXTENSION 0
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#define EXT_SELECTION_ACKS 1
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#define EXT_EXTENSION_BITS 2
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enum {
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EXT_NO_EXTENSION = 0,
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EXT_SELECTION_ACKS = 1,
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EXT_EXTENSION_BITS = 2,
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EXT_NUM_EXT,
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};
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static const value_string bt_utp_extension_type_vals[] = {
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{ EXT_NO_EXTENSION, "No Extension" },
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{ EXT_NO_EXTENSION, "No Extension" },
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{ EXT_SELECTION_ACKS, "Selective acks" },
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{ EXT_EXTENSION_BITS, "Extension bits" },
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{ 0, NULL }
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@ -53,9 +66,43 @@ static const value_string bt_utp_extension_type_vals[] = {
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static int proto_bt_utp = -1;
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/* Specifications: BEP-0029
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/* --- "Original" utp Header ("version 0" ?) --------------
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See utp.cpp source code @ https://github.com/bittorrent/libutp
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-- Fixed Header --
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+-------+-------+---------------+---------------+---------------+
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| connection_id |
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+-------+-------+---------------+---------------+---------------+
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| timestamp_seconds |
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+---------------+---------------+---------------+---------------+
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| timestamp_microseconds |
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+---------------+---------------+---------------+---------------+
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| timestamp_difference_microseconds |
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+---------------+---------------+---------------+---------------+
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| wnd_size | ext | flags | seq_nr [ho] |
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+---------------+---------------+---------------+---------------+
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| seq_nr [lo] | ack_nr |
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+---------------+---------------+---------------+
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-- Extension Field(s) --
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0 8 16
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+---------------+---------------+---------------+---------------+
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| extension | len | bitmask
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+---------------+---------------+---------------+---------------+
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+---------------+---------------+....
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*/
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/* --- Version 1 Header ----------------
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Specifications: BEP-0029
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http://www.bittorrent.org/beps/bep_0029.html
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-- Fixed Header --
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Fields Types
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0 4 8 16 24 32
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+-------+-------+---------------+---------------+---------------+
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@ -70,6 +117,11 @@ Fields Types
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| seq_nr | ack_nr |
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+---------------+---------------+---------------+---------------+
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XXX: It appears that the above is to be interpreted as indicating
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that 'ver' is in the low-order 4 bits of byte 0 (mask: 0x0f).
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(See utp.cpp @ https://github.com/bittorrent/libutp)
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-- Extension Field(s) --
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0 8 16
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+---------------+---------------+---------------+---------------+
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| extension | len | bitmask
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@ -77,17 +129,24 @@ Fields Types
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+---------------+---------------+....
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*/
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#define V1_FIXED_HDR_SIZE 20
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static int hf_bt_utp_ver = -1;
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static int hf_bt_utp_type = -1;
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static int hf_bt_utp_flags = -1;
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static int hf_bt_utp_extension = -1;
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static int hf_bt_utp_next_extension_type = -1;
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static int hf_bt_utp_extension_len = -1;
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static int hf_bt_utp_extension_bitmask = -1;
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static int hf_bt_utp_extension_unknown = -1;
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static int hf_bt_utp_connection_id = -1;
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static int hf_bt_utp_timestamp_ms = -1;
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static int hf_bt_utp_timestamp_diff_ms = -1;
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static int hf_bt_utp_wnd_size = -1;
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static int hf_bt_utp_connection_id_v0 = -1;
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static int hf_bt_utp_connection_id_v1 = -1;
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static int hf_bt_utp_timestamp_sec = -1;
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static int hf_bt_utp_timestamp_us = -1;
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static int hf_bt_utp_timestamp_diff_us = -1;
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static int hf_bt_utp_wnd_size_v0 = -1;
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static int hf_bt_utp_wnd_size_v1 = -1;
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static int hf_bt_utp_seq_nr = -1;
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static int hf_bt_utp_ack_nr = -1;
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@ -98,6 +157,44 @@ static guint global_bt_utp_udp_port = DEFAULT_UDP_PORT;
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void proto_reg_handoff_bt_utp(void);
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static gboolean
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utp_is_v1(tvbuff_t *tvb) {
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guint8 v1_ver_type;
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guint8 v1_ext;
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guint len;
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v1_ver_type = tvb_get_guint8(tvb, 0);
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v1_ext = tvb_get_guint8(tvb, 1);
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if (((v1_ver_type & 0x0f) != 1) ||
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((v1_ver_type>>4) >= ST_NUM_STATES) ||
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(v1_ext >= EXT_NUM_EXT)) {
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return FALSE; /* Not V1 (or corrupt) */
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}
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/* The simple heuristic above (based upon code from utp.cpp) suggests the header is "V1";
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* However, based upon a capture seen, the simple heuristic does not appear to be sufficient.
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* So: Also do some length checking:
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* The length of "V1" frames should be 20, 26, 30, 34, 36, 38, ...
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* fixed hdr len: 20
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* extension9s) len: 6, 10, 14, 16, 18, 20, ...
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* XXX: this is a hack and should be replaced !!
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*/
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len = tvb_reported_length(tvb);
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if (len < V1_FIXED_HDR_SIZE) {
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return TRUE; /* Invalid ?: pretend V1 anyways */
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}
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len -= V1_FIXED_HDR_SIZE;
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if ((len == 0) ||
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(len == 6) ||
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(len == 10) ||
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(len == 14) ||
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((len > 14) && (len%2 == 0))) {
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return TRUE; /* looks like V1 */
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}
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return FALSE; /* Not V1 (or corrupt) */
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}
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static int
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dissect_utp_header(tvbuff_t *tvb, proto_tree *tree)
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{
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@ -105,30 +202,56 @@ dissect_utp_header(tvbuff_t *tvb, proto_tree *tree)
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proto_tree *ext_tree;
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guint8 extension_type;
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guint8 extension_length;
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int offset = 0;
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int offset = 0;
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/* Strange in LibuTP the first bytes as the following definition
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packet_type (4 high bits)
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protocol version (4 low bits)
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*/
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proto_tree_add_item(tree, hf_bt_utp_ver, tvb, offset, 1, FALSE);
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proto_tree_add_item(tree, hf_bt_utp_type, tvb, offset, 1, FALSE);
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offset += 1;
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proto_tree_add_item(tree, hf_bt_utp_next_extension_type, tvb, offset, 1, FALSE);
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extension_type = tvb_get_guint8(tvb, offset);
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offset += 1;
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proto_tree_add_item(tree, hf_bt_utp_connection_id, tvb, offset, 2, FALSE);
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offset += 2;
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proto_tree_add_item(tree, hf_bt_utp_timestamp_ms, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_timestamp_diff_ms, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_wnd_size, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_seq_nr, tvb, offset, 2, FALSE);
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offset += 2;
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proto_tree_add_item(tree, hf_bt_utp_ack_nr, tvb, offset, 2, FALSE);
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offset += 2;
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/* Determine header version */
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if (!utp_is_v1(tvb)) {
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/* "Original" (V0) */
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proto_tree_add_item(tree, hf_bt_utp_connection_id_v0, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_timestamp_sec, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_timestamp_us, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_timestamp_diff_us, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_wnd_size_v0, tvb, offset, 1, FALSE);
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offset += 1;
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proto_tree_add_item(tree, hf_bt_utp_next_extension_type, tvb, offset, 1, FALSE);
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extension_type = tvb_get_guint8(tvb, offset);
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offset += 1;
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proto_tree_add_item(tree, hf_bt_utp_flags, tvb, offset, 1, FALSE);
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offset += 1;
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proto_tree_add_item(tree, hf_bt_utp_seq_nr, tvb, offset, 2, FALSE);
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offset += 2;
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proto_tree_add_item(tree, hf_bt_utp_ack_nr, tvb, offset, 2, FALSE);
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offset += 2;
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} else {
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/* V1 */
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/* Strange: Contrary to BEP-29, in LibuTP (utp.cpp) the first byte has the following definition:
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packet_type (4 high bits)
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protocol version (4 low bits)
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*/
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proto_tree_add_item(tree, hf_bt_utp_ver, tvb, offset, 1, FALSE);
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proto_tree_add_item(tree, hf_bt_utp_type, tvb, offset, 1, FALSE);
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offset += 1;
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proto_tree_add_item(tree, hf_bt_utp_next_extension_type, tvb, offset, 1, FALSE);
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extension_type = tvb_get_guint8(tvb, offset);
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offset += 1;
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proto_tree_add_item(tree, hf_bt_utp_connection_id_v1, tvb, offset, 2, FALSE);
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offset += 2;
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proto_tree_add_item(tree, hf_bt_utp_timestamp_us, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_timestamp_diff_us, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_wnd_size_v1, tvb, offset, 4, FALSE);
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offset += 4;
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proto_tree_add_item(tree, hf_bt_utp_seq_nr, tvb, offset, 2, FALSE);
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offset += 2;
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proto_tree_add_item(tree, hf_bt_utp_ack_nr, tvb, offset, 2, FALSE);
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offset += 2;
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}
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/* display the extension tree */
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@ -136,7 +259,7 @@ dissect_utp_header(tvbuff_t *tvb, proto_tree *tree)
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* ignoring the "end-of-list" [EXT_NO_EXTENSION] extension type.
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* Should we just quit when EXT_NO_EXTENSION is encountered ?
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*/
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while(offset < (int)tvb_length(tvb))
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while(offset < (int)tvb_reported_length(tvb))
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{
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switch(extension_type){
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case EXT_SELECTION_ACKS: /* 1 */
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@ -232,6 +355,11 @@ proto_register_bt_utp(void)
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FT_UINT8, BASE_DEC, NULL, 0x0F,
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NULL, HFILL }
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},
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{ &hf_bt_utp_flags,
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{ "Flags", "bt-utp.flags",
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FT_UINT8, BASE_DEC, VALS(bt_utp_type_vals), 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_type,
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{ "Type", "bt-utp.type",
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FT_UINT8, BASE_DEC, VALS(bt_utp_type_vals), 0xF0,
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@ -262,22 +390,37 @@ proto_register_bt_utp(void)
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FT_BYTES, BASE_NONE, NULL, 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_connection_id,
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{ &hf_bt_utp_connection_id_v0,
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{ "Connection ID", "bt-utp.connection_id",
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FT_UINT32, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_connection_id_v1,
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{ "Connection ID", "bt-utp.connection_id",
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FT_UINT16, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_timestamp_ms,
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{ "Timestamp Microseconds", "bt-utp.timestamp_ms",
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{ &hf_bt_utp_timestamp_sec,
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{ "Timestamp seconds", "bt-utp.timestamp_sec",
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FT_UINT32, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_timestamp_diff_ms,
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{ "Timestamp Difference Microseconds", "bt-utp.timestamp_diff_ms",
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{ &hf_bt_utp_timestamp_us,
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{ "Timestamp Microseconds", "bt-utp.timestamp_us",
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FT_UINT32, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_wnd_size,
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{ &hf_bt_utp_timestamp_diff_us,
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{ "Timestamp Difference Microseconds", "bt-utp.timestamp_diff_us",
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FT_UINT32, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_wnd_size_v0,
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{ "Windows Size", "bt-utp.wnd_size",
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FT_UINT8, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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},
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{ &hf_bt_utp_wnd_size_v1,
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{ "Windows Size", "bt-utp.wnd_size",
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FT_UINT32, BASE_DEC, NULL, 0x0,
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NULL, HFILL }
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