diff options
Diffstat (limited to 'epan/dissectors/packet-bt-dht.c')
| -rw-r--r-- | epan/dissectors/packet-bt-dht.c | 807 |
1 files changed, 807 insertions, 0 deletions
diff --git a/epan/dissectors/packet-bt-dht.c b/epan/dissectors/packet-bt-dht.c new file mode 100644 index 00000000..4d442a76 --- /dev/null +++ b/epan/dissectors/packet-bt-dht.c @@ -0,0 +1,807 @@ +/******************************************************************************************************/ +/* packet-bt-dht.c + * Routines for BT-DHT dissection + * Copyright 2011, Xiao Xiangquan <xiaoxiangquan@gmail.com> + * + * A plugin for BT-DHT packet: + * + * Wireshark - Network traffic analyzer + * By Gerald Combs <gerald@wireshark.org> + * Copyright 1999 Gerald Combs + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include "config.h" + +#include <stdlib.h> + +#include <epan/packet.h> +#include <epan/conversation.h> +#include <epan/prefs.h> +#include <epan/to_str.h> +#include <epan/expert.h> + +#include <wsutil/strtoi.h> + +#define DHT_MIN_LEN 5 + +void proto_register_bt_dht(void); +void proto_reg_handoff_bt_dht(void); + +/* Specifications: + * https://www.bittorrent.org/beps/bep_0005.html BEP 5 DHT Protocol + * https://www.bittorrent.org/beps/bep_0042.html BEP 42 DHT Security extension + */ + +static int proto_bt_dht = -1; +static dissector_handle_t bt_dht_handle; + +/* fields */ +static int hf_bencoded_int = -1; +static int hf_bencoded_string = -1; +static int hf_bencoded_list = -1; +static int hf_bencoded_dict = -1; +static int hf_bencoded_dict_entry = -1; +static int hf_bencoded_list_terminator = -1; + +static int hf_bt_dht_error = -1; +static int hf_bt_dht_peers = -1; +static int hf_bt_dht_peer = -1; +static int hf_bt_dht_nodes = -1; +static int hf_bt_dht_node = -1; +static int hf_bt_dht_id = -1; + +static int hf_ip = -1; +static int hf_ip6 = -1; +static int hf_port = -1; +static int hf_truncated_data = -1; + +static expert_field ei_int_string = EI_INIT; +static expert_field ei_invalid_len = EI_INIT; + +/* tree types */ +static gint ett_bt_dht = -1; +static gint ett_bencoded_list = -1; +static gint ett_bencoded_dict = -1; +static gint ett_bencoded_dict_entry = -1; +static gint ett_bt_dht_error = -1; +static gint ett_bt_dht_peers = -1; +static gint ett_bt_dht_nodes = -1; + +/* some keys use short name in packet */ +static const value_string short_key_name_value_string[] = { + { 'a', "Request arguments" }, + { 'e', "Error" }, + { 'q', "Request type" }, + { 'r', "Response values" }, + { 't', "Transaction ID" }, + { 'v', "Version" }, + { 'y', "Message type" }, + { 0, NULL } +}; + +/* some values use short name in packet */ +static const value_string short_val_name_value_string[] = { + { 'e', "Error" }, + { 'q', "Request" }, + { 'r', "Response" }, + { 0, NULL } +}; + +static const char dict_str[] = "Dictionary..."; +static const char list_str[] = "List..."; + + +static inline bool +bencoded_string_length(packet_info *pinfo, tvbuff_t *tvb, guint *offset_ptr, guint *length) +{ + guint offset, start; + guint remaining = tvb_captured_length_remaining(tvb, *offset_ptr); + if (remaining == 0) + return false; + + offset = *offset_ptr; + start = offset; + + while(tvb_get_guint8(tvb, offset) != ':' && --remaining) + ++offset; + + if (remaining && ws_strtou32(tvb_get_string_enc(pinfo->pool, tvb, start, offset-start, ENC_ASCII), + NULL, length)) { + ++offset; /* skip the ':' */ + *offset_ptr = offset; + return true; + } + return false; +} + + +/* + * dissect a bencoded string from tvb, start at offset. it's like "5:abcde" + * *result will be the decoded value + */ + +static int +dissect_bencoded_string(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char **result, gboolean tohex, const char *label ) +{ + guint string_len; + if (!bencoded_string_length(pinfo, tvb, &offset, &string_len)) + return 0; + + const guint remaining = tvb_captured_length_remaining(tvb, offset); + if (remaining < string_len) + return 0; + + /* fill the return data */ + if (string_len == 0) + *result = ""; + else if (tohex) + *result = tvb_bytes_to_str(pinfo->pool, tvb, offset, string_len ); + else + *result = tvb_get_string_enc( pinfo->pool, tvb, offset, string_len , ENC_ASCII); + + proto_tree_add_string_format( tree, hf_bencoded_string, tvb, offset, string_len, *result, "%s: %s", label, *result ); + offset += string_len; + return offset; +} + +/* + * dissect a bencoded integer from tvb, start at offset. it's like "i5673e" + * *result will be the decoded value + */ +static int +dissect_bencoded_int(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char **result, const char *label ) +{ + guint start_offset; + guint remaining = tvb_captured_length_remaining(tvb, offset); + + /* the shortest valid integer is i0e, so we need at least 3 bytes */ + if (remaining < 3) + return 0; + + if (tvb_get_guint8(tvb, offset) != 'i') + return 0; + + offset += 1; + remaining -= 1; + start_offset = offset; + while (tvb_get_guint8(tvb, offset) != 'e' && --remaining) + offset += 1; + + if (remaining == 0) + return 0; + + proto_tree_add_item(tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII); + + *result = tvb_get_string_enc( pinfo->pool, tvb, start_offset, offset-start_offset, ENC_ASCII); + proto_tree_add_string_format( tree, hf_bencoded_int, tvb, start_offset, offset-start_offset, *result, + "%s: %s", label, *result ); + + offset += 1; + return offset; +} + +/* pre definition of dissect_bencoded_dict(), which is needed by dissect_bencoded_list() */ +static int dissect_bencoded_dict(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char *label ); + +/* dissect a bencoded list from tvb, start at offset. it's like "lXXXe", "X" is any bencoded thing */ +static int +dissect_bencoded_list(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char *label ) +{ + proto_item *ti; + proto_tree *sub_tree; + guint one_byte; + const char *result; + + /* the shortest valid list is "le", so we need at least 2 bytes */ + if (tvb_captured_length_remaining(tvb, offset) < 2) + return 0; + + ti = proto_tree_add_none_format( tree, hf_bencoded_list, tvb, offset, 0, "%s: list...", label ); + sub_tree = proto_item_add_subtree( ti, ett_bencoded_list); + + if (tvb_get_guint8(tvb, offset) != 'l') + return 0; + offset += 1; + + while (tvb_captured_length_remaining(tvb, offset) > 0) + { + one_byte = tvb_get_guint8(tvb, offset); + if (one_byte == 'e') + break; + + guint start_offset = offset; + switch( one_byte ) + { + /* a integer */ + case 'i': + offset = dissect_bencoded_int( tvb, pinfo, sub_tree, offset, &result, "Integer" ); + break; + /* a sub-list */ + case 'l': + offset = dissect_bencoded_list( tvb, pinfo, sub_tree, offset, "Sub-list" ); + break; + /* a dictionary */ + case 'd': + offset = dissect_bencoded_dict( tvb, pinfo, sub_tree, offset, "Sub-dict" ); + break; + /* a string */ + default: + offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, &result, FALSE, "String" ); + break; + } + if (offset <= start_offset) + { + proto_tree_add_expert(sub_tree, pinfo, &ei_int_string, tvb, offset, -1); + /* if offset is not going on, there is no chance to exit the loop, then return*/ + return 0; + } + } + + if (tvb_captured_length_remaining(tvb, offset) == 0) + return 0; + + proto_tree_add_item(sub_tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII); + offset += 1; + return offset; +} + +/* dissect a bt dht error from tvb, start at offset. it's like "li201e9:error msge" */ +static int +dissect_bt_dht_error(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char **result, const char *label ) +{ + proto_item *ti; + proto_tree *sub_tree; + const char *error_no, *error_msg; + + error_no = NULL; + error_msg = NULL; + + ti = proto_tree_add_item( tree, hf_bt_dht_error, tvb, offset, 0, ENC_NA ); + sub_tree = proto_item_add_subtree( ti, ett_bt_dht_error); + + /* we have confirmed that the first byte is 'l' */ + offset += 1; + + /* dissect bt-dht error number and message */ + offset = dissect_bencoded_int( tvb, pinfo, sub_tree, offset, &error_no, "Error ID" ); + if (offset == 0) { + return 0; + } + offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, &error_msg, FALSE, "Error Message" ); + if (offset == 0) { + return 0; + } + + proto_item_set_text( ti, "%s: error %s, %s", label, error_no, error_msg ); + col_append_fstr( pinfo->cinfo, COL_INFO, " No=%s Msg=%s", error_no, error_msg ); + *result = wmem_strdup_printf(pinfo->pool, "error %s, %s", error_no, error_msg ); + + return offset + 1; +} + +/* dissect a bt dht values list from tvb, start at offset. it's like "l6:....6:....e" */ +static int +dissect_bt_dht_values(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char **result, const char *label ) +{ + proto_item *ti; + proto_tree *sub_tree; + proto_item *value_ti; + proto_tree *value_tree; + + guint peer_index; + guint string_len; + + ti = proto_tree_add_item( tree, hf_bt_dht_peers, tvb, offset, 0, ENC_NA ); + sub_tree = proto_item_add_subtree( ti, ett_bt_dht_peers); + + peer_index = 0; + /* we has confirmed that the first byte is 'l' */ + offset += 1; + + /* dissect bt-dht values */ + while( tvb_get_guint8(tvb,offset)!='e' ) + { + if (!bencoded_string_length(pinfo, tvb, &offset, &string_len)) + { + expert_add_info(pinfo, ti, &ei_invalid_len); + // Fail hard here rather than potentially looping excessively. + return 0; + } + else if (string_len == 6) + { + /* 4 bytes ip, 2 bytes port */ + peer_index += 1; + + value_ti = proto_tree_add_item( sub_tree, hf_bt_dht_peer, tvb, offset, 6, ENC_NA ); + proto_item_append_text(value_ti, " %d", peer_index); + value_tree = proto_item_add_subtree( value_ti, ett_bt_dht_peers); + + proto_tree_add_item( value_tree, hf_ip, tvb, offset, 4, ENC_BIG_ENDIAN); + proto_item_append_text(value_ti, " (IP/Port: %s", tvb_ip_to_str(pinfo->pool, tvb, offset)); + proto_tree_add_item( value_tree, hf_port, tvb, offset+4, 2, ENC_BIG_ENDIAN); + proto_item_append_text(value_ti, ":%u)", tvb_get_ntohs( tvb, offset+4 )); + } + else if (string_len == 18) + { + /* 16 bytes ip, 2 bytes port */ + peer_index += 1; + + value_ti = proto_tree_add_item( sub_tree, hf_bt_dht_peer, tvb, offset, 18, ENC_NA ); + proto_item_append_text(value_ti, " %d", peer_index); + value_tree = proto_item_add_subtree( value_ti, ett_bt_dht_peers); + + proto_tree_add_item( value_tree, hf_ip6, tvb, offset, 16, ENC_NA); + proto_item_append_text(value_ti, " (IPv6/Port: [%s]", tvb_ip6_to_str(pinfo->pool, tvb, offset)); + proto_tree_add_item( value_tree, hf_port, tvb, offset+16, 2, ENC_BIG_ENDIAN); + proto_item_append_text(value_ti, ":%u)", tvb_get_ntohs( tvb, offset+16 )); + } + else + { + /* truncated data */ + proto_tree_add_item( tree, hf_truncated_data, tvb, offset, string_len, ENC_NA ); + } + + offset += string_len; + } + + if (tvb_get_guint8(tvb,offset)=='e') { /* list ending delimiter */ + proto_tree_add_item(sub_tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII); + offset++; + } + + proto_item_set_text( ti, "%s: %d peers", label, peer_index ); + col_append_fstr( pinfo->cinfo, COL_INFO, " Peers=%d", peer_index ); + *result = wmem_strdup_printf(pinfo->pool, "%d peers", peer_index); + + return offset; +} + +static int +dissect_bt_dht_nodes(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char **result, const char *label, gboolean is_ipv6 ) +{ + proto_item *ti; + proto_tree *sub_tree; + proto_item *node_ti; + proto_tree *node_tree; + + guint node_index; + guint string_len; + guint node_byte_length; + + if (!bencoded_string_length(pinfo, tvb, &offset, &string_len)) + return 0; + + ti = proto_tree_add_item( tree, hf_bt_dht_nodes, tvb, offset, string_len, ENC_NA ); + sub_tree = proto_item_add_subtree( ti, ett_bt_dht_nodes); + node_index = 0; + + /* 26 bytes = 20 bytes id + 4 bytes ipv4 address + 2 bytes port */ + node_byte_length = 26; + + if ( is_ipv6 ) + { + /* 38 bytes = 20 bytes id + 16 bytes ipv6 address + 2 bytes port */ + node_byte_length = 38; + } + + for( ; string_len>=node_byte_length; string_len-=node_byte_length, offset+=node_byte_length ) + { + node_index += 1; + + node_ti = proto_tree_add_item( sub_tree, hf_bt_dht_node, tvb, offset, node_byte_length, ENC_NA); + proto_item_append_text(node_ti, " %d", node_index); + node_tree = proto_item_add_subtree( node_ti, ett_bt_dht_peers); + + proto_tree_add_item( node_tree, hf_bt_dht_id, tvb, offset, 20, ENC_NA); + proto_item_append_text(node_ti, " (id: %s", tvb_bytes_to_str(pinfo->pool, tvb, offset, 20)); + + if ( is_ipv6 ) + { + proto_tree_add_item( node_tree, hf_ip6, tvb, offset+20, 16, ENC_NA); + proto_item_append_text(node_ti, ", IPv6/Port: [%s]", tvb_ip6_to_str(pinfo->pool, tvb, offset+20)); + + proto_tree_add_item( node_tree, hf_port, tvb, offset+36, 2, ENC_BIG_ENDIAN); + proto_item_append_text(node_ti, ":%u)", tvb_get_ntohs( tvb, offset+36 )); + } + else + { + proto_tree_add_item( node_tree, hf_ip, tvb, offset+20, 4, ENC_BIG_ENDIAN); + proto_item_append_text(node_ti, ", IPv4/Port: %s", tvb_ip_to_str(pinfo->pool, tvb, offset+20)); + + proto_tree_add_item( node_tree, hf_port, tvb, offset+24, 2, ENC_BIG_ENDIAN); + proto_item_append_text(node_ti, ":%u)", tvb_get_ntohs( tvb, offset+24 )); + } + } + + if( string_len>0 ) + { + proto_tree_add_item( tree, hf_truncated_data, tvb, offset, string_len, ENC_NA ); + offset += string_len; + } + proto_item_set_text( ti, "%s: %d nodes", label, node_index ); + col_append_fstr( pinfo->cinfo, COL_INFO, " Nodes=%d", node_index ); + *result = wmem_strdup_printf(pinfo->pool, "%d", node_index); + + return offset; +} + +static int +dissect_bencoded_dict_entry(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset ) +{ + proto_item *ti; + proto_tree *sub_tree; + gboolean tohex; + const char *key; + const char *val; + guint orig_offset = offset; + + key = NULL; + val = NULL; + + ti = proto_tree_add_item( tree, hf_bencoded_dict_entry, tvb, offset, 0, ENC_NA ); + sub_tree = proto_item_add_subtree( ti, ett_bencoded_dict_entry); + + /* dissect the key, it must be a string */ + offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, &key, FALSE, "Key" ); + if (offset == 0) + { + proto_tree_add_expert_format(sub_tree, pinfo, &ei_int_string, tvb, offset, -1, "Invalid string for Key"); + return 0; + } + + if (tvb_captured_length_remaining(tvb, offset) == 0) + return 0; + + /* If it is a dict, then just do recursion */ + switch( tvb_get_guint8(tvb,offset) ) + { + case 'd': + offset = dissect_bencoded_dict( tvb, pinfo, sub_tree, offset, "Value" ); + val = dict_str; + break; + case 'l': + if( strcmp(key,"e")==0 ) + offset = dissect_bt_dht_error( tvb, pinfo, sub_tree, offset, &val, "Value" ); + else if( strcmp(key,"values")==0 ) + offset = dissect_bt_dht_values( tvb, pinfo, sub_tree, offset, &val, "Value" ); + /* other unfamiliar lists */ + else + { + offset = dissect_bencoded_list( tvb, pinfo, sub_tree, offset, "Value" ); + val = list_str; + } + break; + case 'i': + offset = dissect_bencoded_int( tvb, pinfo, sub_tree, offset, &val, "Value" ); + break; + /* it's a string */ + default: + /* special process */ + if( strcmp(key,"nodes")==0 ) + { + offset = dissect_bt_dht_nodes( tvb, pinfo, sub_tree, offset, &val, "Value", 0 ); + } + else if( strcmp(key,"nodes6")==0 ) + { + offset = dissect_bt_dht_nodes( tvb, pinfo, sub_tree, offset, &val, "Value", 1 ); + } + else if( strcmp(key,"ip")==0 ) + { + /* + * BEP 42 DHT Security extension + * https://www.bittorrent.org/beps/bep_0042.html + * https://www.rasterbar.com/products/libtorrent/dht_sec.html + */ + + guint len; + int old_offset = offset; + if (!bencoded_string_length(pinfo, tvb, &offset, &len)) { + proto_tree_add_expert_format(sub_tree, pinfo, &ei_int_string, tvb, offset, -1, "Invalid string for value"); + return 0; + } + + if(len == 6) { + proto_tree_add_item(sub_tree, hf_ip, tvb, offset, 4, ENC_BIG_ENDIAN); + val = tvb_ip_to_str(pinfo->pool, tvb, offset); + offset += 4; + proto_tree_add_item(sub_tree, hf_port, tvb, offset, 2, ENC_BIG_ENDIAN); + offset += 2; + } + else { + /* XXX: BEP 42 doesn't mention IPv6 and predates the IPv6 DHT; + * it doesn't make sense for IPv6 because the purpose is to tell + * the requestor its own publicly routable IP address and port + * (working around NAT). So any other length than 6 is unexpected. + */ + offset = dissect_bencoded_string( tvb, pinfo, sub_tree, old_offset, &val, TRUE, "Value" ); + } + } + else + { + /* some need to return hex string */ + tohex = strcmp(key,"id")==0 || strcmp(key,"target")==0 + || strcmp(key,"info_hash")==0 || strcmp(key,"t")==0 + || strcmp(key,"v")==0 || strcmp(key,"token")==0; + offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, &val, tohex, "Value" ); + } + } + + if (offset == 0) + { + proto_tree_add_expert_format(sub_tree, pinfo, &ei_int_string, tvb, offset, -1, "Invalid string for value"); + return 0; + } + + if(key && strcmp(key,"q")==0 && strlen(val)>1 ) + col_prepend_fstr(pinfo->cinfo, COL_INFO, "%c%s", g_ascii_toupper(val[0]), val + 1); + if(key && strcmp(key,"r")==0 ) + col_prepend_fstr(pinfo->cinfo, COL_INFO, "Response"); + if(key && strcmp(key,"e")==0 ) + col_prepend_fstr(pinfo->cinfo, COL_INFO, "Error"); + if(key && (strcmp(key,"info_hash")==0 || strcmp(key,"target")==0) ) + col_append_fstr(pinfo->cinfo, COL_INFO, " %c%s=%s", g_ascii_toupper(key[0]), key + 1, val); + + if(key && strlen(key)==1 ) + key = val_to_str_const( key[0], short_key_name_value_string, key ); + if(val && strlen(val)==1 ) + val = val_to_str_const( val[0], short_val_name_value_string, val ); + + proto_item_set_text( ti, "%s: %s", key, val ); + proto_item_set_len( ti, offset-orig_offset ); + + return offset; +} + +/* dict = d...e */ +static int +dissect_bencoded_dict(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset, const char *label ) +{ + proto_item *ti; + proto_tree *sub_tree; + guint orig_offset = offset; + + /* the shortest valid dictionary is "de", so we need at least 2 bytes */ + if (tvb_captured_length_remaining(tvb, offset) < 2) + return 0; + + if(offset == 0) + { + ti = proto_tree_add_item(tree, proto_bt_dht, tvb, 0, -1, ENC_NA); + sub_tree = proto_item_add_subtree(ti, ett_bt_dht); + } + else + { + ti = proto_tree_add_none_format( tree, hf_bencoded_dict, tvb, offset, -1, "%s: Dictionary...", label ); + sub_tree = proto_item_add_subtree( ti, ett_bencoded_dict); + } + + if (tvb_get_guint8(tvb, offset) != 'd') + return 0; + offset += 1; + + while (tvb_captured_length_remaining(tvb, offset) > 0) { + if (tvb_get_guint8(tvb, offset) == 'e') + break; + + offset = dissect_bencoded_dict_entry( tvb, pinfo, sub_tree, offset ); + if (offset == 0) + { + proto_tree_add_expert(sub_tree, pinfo, &ei_int_string, tvb, offset, -1); + return 0; + } + } + + if (tvb_captured_length_remaining(tvb, offset) == 0) + return 0; + + proto_tree_add_item(sub_tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII); + offset += 1; + proto_item_set_len( ti, offset-orig_offset ); + + return offset; +} + +static gboolean +test_bt_dht(packet_info *pinfo _U_, tvbuff_t *tvb, int offset, void *data _U_) +{ + + /* The DHT KRPC protocol sends packets that are bencoded dictionaries. + * Bencoded dictionaries always have the keys in sorted (raw string) + * order. There are three possible message types, query, which has "a" and + * "q" keys that map to dictionaries, response, which has an "r" key + * that maps to a dictionary, and error, which has an "e" key that maps + * to a list. + * + * Conveniently, those keys appear in sort order before all other possible + * top level keys, with the exception of the "ip" key added in BEP-0042. + * + * Thus, there are only four possible initial sets of bytes, corresponding + * to beginning with an "a" dictionary, "r" dictionary, "ip" string, or an + * "e" list. + */ + + if (tvb_captured_length_remaining(tvb, offset) < DHT_MIN_LEN) + return FALSE; + + if (tvb_memeql(tvb, offset, (const guint8*)"d1:ad", 5) == 0) { + return TRUE; + } else if (tvb_memeql(tvb, offset, (const guint8*)"d1:rd", 5) == 0) { + return TRUE; + } else if (tvb_memeql(tvb, offset, (const guint8*)"d2:ip", 5) == 0) { + return TRUE; + } else if (tvb_memeql(tvb, offset, (const guint8*)"d1:el", 5) == 0) { + return TRUE; + } + + return FALSE; +} + +static int +dissect_bt_dht(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data) +{ + /* BitTorrent clients use the same UDP connection for DHT as for uTP. + * So even if this has been set as the dissector for this conversation + * or port, test it and reject it if not BT-DHT in order to give other + * dissectors, especially BT-uTP, a chance. + */ + if (!test_bt_dht(pinfo, tvb, 0, data)) { + return 0; + } + + col_set_str(pinfo->cinfo, COL_PROTOCOL, "BT-DHT"); + col_clear(pinfo->cinfo, COL_INFO); + + /* XXX: There is a separate "bencode" dissector. Would it be possible + * to use it, at least to move some functions into a shared header? + * DHT has some keys with special meanings, and some values that + * are supposed to be interpreted specially (e.g., IP/port combinations), + * so maybe it's more trouble than it's worth. + */ + return dissect_bencoded_dict(tvb, pinfo, tree, 0, "BitTorrent DHT Protocol"); +} + +static +gboolean dissect_bt_dht_heur (tvbuff_t *tvb, packet_info *pinfo, + proto_tree *tree, void *data) +{ + conversation_t *conversation; + + if (!test_bt_dht(pinfo, tvb, 0, data)) { + return FALSE; + } + + conversation = find_or_create_conversation(pinfo); + conversation_set_dissector_from_frame_number(conversation, pinfo->num, bt_dht_handle); + + dissect_bt_dht(tvb, pinfo, tree, NULL); + return TRUE; +} + +void +proto_register_bt_dht(void) +{ + expert_module_t* expert_bt_dht; + + static hf_register_info hf[] = { + { &hf_bencoded_string, + { "String", "bt-dht.bencoded.string", + FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bencoded_list, + { "List", "bt-dht.bencoded.list", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bencoded_int, + { "Int", "bt-dht.bencoded.int", + FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bencoded_dict, + { "Dictionary", "bt-dht.bencoded.dict", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bencoded_dict_entry, + { "Dictionary Entry", "bt-dht.bencoded.dict_entry", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bencoded_list_terminator, + { "Terminator", "bt-dht.bencoded.list.terminator", + FT_STRING, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bt_dht_error, + { "Error", "bt-dht.error", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bt_dht_peer, + { "Peer", "bt-dht.peer", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bt_dht_peers, + { "Peers", "bt-dht.peers", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bt_dht_node, + { "Node", "bt-dht.node", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bt_dht_nodes, + { "Nodes", "bt-dht.nodes", + FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_bt_dht_id, + { "ID", "bt-dht.id", + FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_ip, + { "IP", "bt-dht.ip", + FT_IPv4, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_ip6, + { "IP", "bt-dht.ip6", + FT_IPv6, BASE_NONE, NULL, 0x0, NULL, HFILL } + }, + { &hf_port, + { "Port", "bt-dht.port", + FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } + }, + { &hf_truncated_data, + { "Truncated data", "bt-dht.truncated_data", + FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } + } + }; + + static ei_register_info ei[] = { + { &ei_int_string, { "bt-dht.invalid_string", PI_MALFORMED, PI_ERROR, + "String must contain an integer", EXPFILL }}, + { &ei_invalid_len, { "bt-dht.invalid_length", PI_MALFORMED, PI_ERROR, + "Invalid length", EXPFILL }}, + }; + + /* Setup protocol subtree array */ + static gint *ett[] = { + &ett_bt_dht, + &ett_bencoded_list, + &ett_bencoded_dict, + &ett_bt_dht_error, + &ett_bt_dht_peers, + &ett_bt_dht_nodes, + &ett_bencoded_dict_entry + }; + + module_t *bt_dht_module; + + proto_bt_dht = proto_register_protocol ("BitTorrent DHT Protocol", "BT-DHT", "bt-dht"); + + bt_dht_module = prefs_register_protocol(proto_bt_dht, NULL); + prefs_register_obsolete_preference(bt_dht_module, "enable"); + + proto_register_field_array(proto_bt_dht, hf, array_length(hf)); + proto_register_subtree_array(ett, array_length(ett)); + + expert_bt_dht = expert_register_protocol(proto_bt_dht); + expert_register_field_array(expert_bt_dht, ei, array_length(ei)); + + bt_dht_handle = register_dissector("bt-dht", dissect_bt_dht, proto_bt_dht); +} + +void +proto_reg_handoff_bt_dht(void) +{ + heur_dissector_add("udp", dissect_bt_dht_heur, "BitTorrent DHT over UDP", "bittorrent_dht_udp", proto_bt_dht, HEURISTIC_ENABLE); + + dissector_add_for_decode_as_with_preference("udp.port", bt_dht_handle); +} + +/* + * Editor modelines + * + * Local Variables: + * c-basic-offset: 2 + * tab-width: 8 + * indent-tabs-mode: nil + * End: + * + * ex: set shiftwidth=2 tabstop=8 expandtab: + * :indentSize=2:tabSize=8:noTabs=true: + */ |