Bug Summary

File:builds/wireshark/wireshark/epan/dissectors/packet-bt-dht.c
Warning:line 553, column 13
Null pointer passed to 1st parameter expecting 'nonnull'

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name packet-bt-dht.c -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -fno-delete-null-pointer-checks -mframe-pointer=all -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -ffloat16-excess-precision=fast -fbfloat16-excess-precision=fast -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/builds/wireshark/wireshark/build -fcoverage-compilation-dir=/builds/wireshark/wireshark/build -resource-dir /usr/lib/llvm-18/lib/clang/18 -isystem /usr/include/glib-2.0 -isystem /usr/lib/x86_64-linux-gnu/glib-2.0/include -isystem /usr/include/mit-krb5 -isystem /usr/include/libxml2 -isystem /builds/wireshark/wireshark/build/epan/dissectors -isystem /builds/wireshark/wireshark/epan/dissectors -isystem /builds/wireshark/wireshark/epan -D G_DISABLE_DEPRECATED -D G_DISABLE_SINGLE_INCLUDES -D WS_BUILD_DLL -D WS_DEBUG -D WS_DEBUG_UTF_8 -I /builds/wireshark/wireshark/build -I /builds/wireshark/wireshark -I /builds/wireshark/wireshark/include -D _GLIBCXX_ASSERTIONS -internal-isystem /usr/lib/llvm-18/lib/clang/18/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/builds/wireshark/wireshark/= -fmacro-prefix-map=/builds/wireshark/wireshark/build/= -fmacro-prefix-map=../= -Wno-format-truncation -Wno-format-nonliteral -Wno-pointer-sign -std=gnu11 -ferror-limit 19 -fvisibility=hidden -fwrapv -fstrict-flex-arrays=3 -stack-protector 2 -fstack-clash-protection -fcf-protection=full -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fexceptions -fcolor-diagnostics -analyzer-output=html -dwarf-debug-flags /usr/lib/llvm-18/bin/clang -### --analyze -x c -D G_DISABLE_DEPRECATED -D G_DISABLE_SINGLE_INCLUDES -D WS_BUILD_DLL -D WS_DEBUG -D WS_DEBUG_UTF_8 -I /builds/wireshark/wireshark/build -I /builds/wireshark/wireshark -I /builds/wireshark/wireshark/include -isystem /usr/include/glib-2.0 -isystem /usr/lib/x86_64-linux-gnu/glib-2.0/include -isystem /usr/include/mit-krb5 -isystem /usr/include/libxml2 -isystem /builds/wireshark/wireshark/build/epan/dissectors -isystem /builds/wireshark/wireshark/epan/dissectors -isystem /builds/wireshark/wireshark/epan -fvisibility=hidden -fexcess-precision=fast -fstrict-flex-arrays=3 -fstack-clash-protection -fcf-protection=full -D _GLIBCXX_ASSERTIONS -fstack-protector-strong -fno-delete-null-pointer-checks -fno-strict-overflow -fno-strict-aliasing -fexceptions -Wno-format-truncation -Wno-format-nonliteral -fdiagnostics-color=always -Wno-pointer-sign -fmacro-prefix-map=/builds/wireshark/wireshark/= -fmacro-prefix-map=/builds/wireshark/wireshark/build/= -fmacro-prefix-map=../= -std=gnu11 -fPIC /builds/wireshark/wireshark/epan/dissectors/packet-bt-dht.c -o /builds/wireshark/wireshark/sbout/2024-11-21-100252-3913-1 -Xclang -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /builds/wireshark/wireshark/sbout/2024-11-21-100252-3913-1 -x c /builds/wireshark/wireshark/epan/dissectors/packet-bt-dht.c
1/******************************************************************************************************/
2/* packet-bt-dht.c
3 * Routines for BT-DHT dissection
4 * Copyright 2011, Xiao Xiangquan <[email protected]>
5 *
6 * A plugin for BT-DHT packet:
7 *
8 * Wireshark - Network traffic analyzer
9 * By Gerald Combs <[email protected]>
10 * Copyright 1999 Gerald Combs
11 *
12 * SPDX-License-Identifier: GPL-2.0-or-later
13 */
14
15#include "config.h"
16
17#include <stdlib.h>
18
19#include <epan/packet.h>
20#include <epan/conversation.h>
21#include <epan/prefs.h>
22#include <epan/to_str.h>
23#include <epan/expert.h>
24
25#include <wsutil/strtoi.h>
26
27#define DHT_MIN_LEN5 5
28
29void proto_register_bt_dht(void);
30void proto_reg_handoff_bt_dht(void);
31
32/* Specifications:
33 * https://www.bittorrent.org/beps/bep_0005.html BEP 5 DHT Protocol
34 * https://www.bittorrent.org/beps/bep_0042.html BEP 42 DHT Security extension
35 */
36
37static int proto_bt_dht;
38static dissector_handle_t bt_dht_handle;
39
40/* fields */
41static int hf_bencoded_int;
42static int hf_bencoded_string;
43static int hf_bencoded_list;
44static int hf_bencoded_dict;
45static int hf_bencoded_dict_entry;
46static int hf_bencoded_list_terminator;
47
48static int hf_bt_dht_error;
49static int hf_bt_dht_peers;
50static int hf_bt_dht_peer;
51static int hf_bt_dht_nodes;
52static int hf_bt_dht_node;
53static int hf_bt_dht_id;
54
55static int hf_ip;
56static int hf_ip6;
57static int hf_port;
58static int hf_truncated_data;
59
60static expert_field ei_int_string;
61static expert_field ei_invalid_len;
62static expert_field ei_duplicate_dict_keys;
63static expert_field ei_unsorted_dict_keys;
64
65/* tree types */
66static int ett_bt_dht;
67static int ett_bencoded_list;
68static int ett_bencoded_dict;
69static int ett_bencoded_dict_entry;
70static int ett_bt_dht_error;
71static int ett_bt_dht_peers;
72static int ett_bt_dht_nodes;
73
74/* some keys use short name in packet */
75static const value_string short_key_name_value_string[] = {
76 { 'a', "Request arguments" },
77 { 'e', "Error" },
78 { 'q', "Request type" },
79 { 'r', "Response values" },
80 { 't', "Transaction ID" },
81 { 'v', "Version" },
82 { 'y', "Message type" },
83 { 0, NULL((void*)0) }
84};
85
86/* some values use short name in packet */
87static const value_string short_val_name_value_string[] = {
88 { 'e', "Error" },
89 { 'q', "Request" },
90 { 'r', "Response" },
91 { 0, NULL((void*)0) }
92};
93
94static const char dict_str[] = "Dictionary...";
95static const char list_str[] = "List...";
96
97
98static inline bool_Bool
99bencoded_string_length(packet_info *pinfo, tvbuff_t *tvb, unsigned *offset_ptr, unsigned *length)
100{
101 unsigned offset, start;
102 unsigned remaining = tvb_captured_length_remaining(tvb, *offset_ptr);
103 if (remaining == 0)
104 return false0;
105
106 offset = *offset_ptr;
107 start = offset;
108
109 while(tvb_get_uint8(tvb, offset) != ':' && --remaining)
110 ++offset;
111
112 if (remaining && ws_strtou32(tvb_get_string_enc(pinfo->pool, tvb, start, offset-start, ENC_ASCII0x00000000),
113 NULL((void*)0), length)) {
114 ++offset; /* skip the ':' */
115 *offset_ptr = offset;
116 return true1;
117 }
118 return false0;
119}
120
121
122/*
123 * dissect a bencoded string from tvb, start at offset. it's like "5:abcde"
124 * *result will be the decoded value
125 */
126
127static int
128dissect_bencoded_string(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char **result, bool_Bool tohex, const char *label )
129{
130 unsigned string_len;
131 if (!bencoded_string_length(pinfo, tvb, &offset, &string_len))
16
←
Assuming the condition is false
→
17
←
Taking false branch
→
132 return 0;
133
134 const unsigned remaining = tvb_captured_length_remaining(tvb, offset);
135 if (remaining < string_len)
18
←
Assuming 'remaining' is >= 'string_len'
→
19
←
Taking false branch
→
136 return 0;
137
138 /* fill the return data */
139 if (string_len == 0)
20
←
Assuming 'string_len' is not equal to 0
→
21
←
Taking false branch
→
140 *result = "";
141 else if (tohex
21.1
'tohex' is false
)
22
←
Taking false branch
→
142 *result = tvb_bytes_to_str(pinfo->pool, tvb, offset, string_len );
143 else
144 *result = tvb_get_string_enc( pinfo->pool, tvb, offset, string_len , ENC_ASCII0x00000000);
23
←
Value assigned to 'key'
→
145
146 proto_tree_add_string_format( tree, hf_bencoded_string, tvb, offset, string_len, *result, "%s: %s", label, *result );
147 offset += string_len;
148 return offset;
149}
150
151/*
152 * dissect a bencoded integer from tvb, start at offset. it's like "i5673e"
153 * *result will be the decoded value
154 */
155static int
156dissect_bencoded_int(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char **result, const char *label )
157{
158 unsigned start_offset;
159 unsigned remaining = tvb_captured_length_remaining(tvb, offset);
160
161 /* the shortest valid integer is i0e, so we need at least 3 bytes */
162 if (remaining < 3)
163 return 0;
164
165 if (tvb_get_uint8(tvb, offset) != 'i')
166 return 0;
167
168 offset += 1;
169 remaining -= 1;
170 start_offset = offset;
171 while (tvb_get_uint8(tvb, offset) != 'e' && --remaining)
172 offset += 1;
173
174 if (remaining == 0)
175 return 0;
176
177 proto_tree_add_item(tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII0x00000000);
178
179 *result = tvb_get_string_enc( pinfo->pool, tvb, start_offset, offset-start_offset, ENC_ASCII0x00000000);
180 proto_tree_add_string_format( tree, hf_bencoded_int, tvb, start_offset, offset-start_offset, *result,
181 "%s: %s", label, *result );
182
183 offset += 1;
184 return offset;
185}
186
187/* pre definition of dissect_bencoded_dict(), which is needed by dissect_bencoded_list() */
188static int dissect_bencoded_dict(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char *label );
189
190/* dissect a bencoded list from tvb, start at offset. it's like "lXXXe", "X" is any bencoded thing */
191static int
192// NOLINTNEXTLINE(misc-no-recursion)
193dissect_bencoded_list(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char *label )
194{
195 proto_item *ti;
196 proto_tree *sub_tree;
197 unsigned one_byte;
198 const char *result;
199
200 /* the shortest valid list is "le", so we need at least 2 bytes */
201 if (tvb_captured_length_remaining(tvb, offset) < 2)
202 return 0;
203
204 ti = proto_tree_add_none_format( tree, hf_bencoded_list, tvb, offset, 0, "%s: list...", label );
205 sub_tree = proto_item_add_subtree( ti, ett_bencoded_list);
206
207 if (tvb_get_uint8(tvb, offset) != 'l')
208 return 0;
209 offset += 1;
210
211 while (tvb_captured_length_remaining(tvb, offset) > 0)
212 {
213 one_byte = tvb_get_uint8(tvb, offset);
214 if (one_byte == 'e')
215 break;
216
217 unsigned start_offset = offset;
218 switch( one_byte )
219 {
220 /* a integer */
221 case 'i':
222 offset = dissect_bencoded_int( tvb, pinfo, sub_tree, offset, &result, "Integer" );
223 break;
224 /* a sub-list */
225 case 'l':
226 offset = dissect_bencoded_list( tvb, pinfo, sub_tree, offset, "Sub-list" );
227 break;
228 /* a dictionary */
229 case 'd':
230 offset = dissect_bencoded_dict( tvb, pinfo, sub_tree, offset, "Sub-dict" );
231 break;
232 /* a string */
233 default:
234 offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, &result, false0, "String" );
235 break;
236 }
237 if (offset <= start_offset)
238 {
239 proto_tree_add_expert(sub_tree, pinfo, &ei_int_string, tvb, offset, -1);
240 /* if offset is not going on, there is no chance to exit the loop, then return*/
241 return 0;
242 }
243 }
244
245 if (tvb_captured_length_remaining(tvb, offset) == 0)
246 return 0;
247
248 proto_tree_add_item(sub_tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII0x00000000);
249 offset += 1;
250 return offset;
251}
252
253/* dissect a bt dht error from tvb, start at offset. it's like "li201e9:error msge" */
254static int
255dissect_bt_dht_error(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char **result, const char *label )
256{
257 proto_item *ti;
258 proto_tree *sub_tree;
259 const char *error_no, *error_msg;
260
261 error_no = NULL((void*)0);
262 error_msg = NULL((void*)0);
263
264 ti = proto_tree_add_item( tree, hf_bt_dht_error, tvb, offset, 0, ENC_NA0x00000000 );
265 sub_tree = proto_item_add_subtree( ti, ett_bt_dht_error);
266
267 /* we have confirmed that the first byte is 'l' */
268 offset += 1;
269
270 /* dissect bt-dht error number and message */
271 offset = dissect_bencoded_int( tvb, pinfo, sub_tree, offset, &error_no, "Error ID" );
272 if (offset == 0) {
273 return 0;
274 }
275 offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, &error_msg, false0, "Error Message" );
276 if (offset == 0) {
277 return 0;
278 }
279
280 proto_item_set_text( ti, "%s: error %s, %s", label, error_no, error_msg );
281 col_append_fstr( pinfo->cinfo, COL_INFO, " No=%s Msg=%s", error_no, error_msg );
282 *result = wmem_strdup_printf(pinfo->pool, "error %s, %s", error_no, error_msg );
283
284 return offset + 1;
285}
286
287/* dissect a bt dht values list from tvb, start at offset. it's like "l6:....6:....e" */
288static int
289dissect_bt_dht_values(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char **result, const char *label )
290{
291 proto_item *ti;
292 proto_tree *sub_tree;
293 proto_item *value_ti;
294 proto_tree *value_tree;
295
296 unsigned peer_index;
297 unsigned string_len;
298
299 ti = proto_tree_add_item( tree, hf_bt_dht_peers, tvb, offset, 0, ENC_NA0x00000000 );
300 sub_tree = proto_item_add_subtree( ti, ett_bt_dht_peers);
301
302 peer_index = 0;
303 /* we has confirmed that the first byte is 'l' */
304 offset += 1;
305
306 /* dissect bt-dht values */
307 while( tvb_get_uint8(tvb,offset)!='e' )
308 {
309 if (!bencoded_string_length(pinfo, tvb, &offset, &string_len))
310 {
311 expert_add_info(pinfo, ti, &ei_invalid_len);
312 // Fail hard here rather than potentially looping excessively.
313 return 0;
314 }
315 else if (string_len == 6)
316 {
317 /* 4 bytes ip, 2 bytes port */
318 peer_index += 1;
319
320 value_ti = proto_tree_add_item( sub_tree, hf_bt_dht_peer, tvb, offset, 6, ENC_NA0x00000000 );
321 proto_item_append_text(value_ti, " %d", peer_index);
322 value_tree = proto_item_add_subtree( value_ti, ett_bt_dht_peers);
323
324 proto_tree_add_item( value_tree, hf_ip, tvb, offset, 4, ENC_BIG_ENDIAN0x00000000);
325 proto_item_append_text(value_ti, " (IP/Port: %s", tvb_ip_to_str(pinfo->pool, tvb, offset)tvb_address_to_str(pinfo->pool, tvb, AT_IPv4, offset));
326 proto_tree_add_item( value_tree, hf_port, tvb, offset+4, 2, ENC_BIG_ENDIAN0x00000000);
327 proto_item_append_text(value_ti, ":%u)", tvb_get_ntohs( tvb, offset+4 ));
328 }
329 else if (string_len == 18)
330 {
331 /* 16 bytes ip, 2 bytes port */
332 peer_index += 1;
333
334 value_ti = proto_tree_add_item( sub_tree, hf_bt_dht_peer, tvb, offset, 18, ENC_NA0x00000000 );
335 proto_item_append_text(value_ti, " %d", peer_index);
336 value_tree = proto_item_add_subtree( value_ti, ett_bt_dht_peers);
337
338 proto_tree_add_item( value_tree, hf_ip6, tvb, offset, 16, ENC_NA0x00000000);
339 proto_item_append_text(value_ti, " (IPv6/Port: [%s]", tvb_ip6_to_str(pinfo->pool, tvb, offset)tvb_address_to_str(pinfo->pool, tvb, AT_IPv6, offset));
340 proto_tree_add_item( value_tree, hf_port, tvb, offset+16, 2, ENC_BIG_ENDIAN0x00000000);
341 proto_item_append_text(value_ti, ":%u)", tvb_get_ntohs( tvb, offset+16 ));
342 }
343 else
344 {
345 /* truncated data */
346 proto_tree_add_item( tree, hf_truncated_data, tvb, offset, string_len, ENC_NA0x00000000 );
347 }
348
349 offset += string_len;
350 }
351
352 if (tvb_get_uint8(tvb,offset)=='e') { /* list ending delimiter */
353 proto_tree_add_item(sub_tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII0x00000000);
354 offset++;
355 }
356
357 proto_item_set_text( ti, "%s: %d peers", label, peer_index );
358 col_append_fstr( pinfo->cinfo, COL_INFO, " Peers=%d", peer_index );
359 *result = wmem_strdup_printf(pinfo->pool, "%d peers", peer_index);
360
361 return offset;
362}
363
364static int
365dissect_bt_dht_nodes(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char **result, const char *label, bool_Bool is_ipv6 )
366{
367 proto_item *ti;
368 proto_tree *sub_tree;
369 proto_item *node_ti;
370 proto_tree *node_tree;
371
372 unsigned node_index;
373 unsigned string_len;
374 unsigned node_byte_length;
375
376 if (!bencoded_string_length(pinfo, tvb, &offset, &string_len))
377 return 0;
378
379 ti = proto_tree_add_item( tree, hf_bt_dht_nodes, tvb, offset, string_len, ENC_NA0x00000000 );
380 sub_tree = proto_item_add_subtree( ti, ett_bt_dht_nodes);
381 node_index = 0;
382
383 /* 26 bytes = 20 bytes id + 4 bytes ipv4 address + 2 bytes port */
384 node_byte_length = 26;
385
386 if ( is_ipv6 )
387 {
388 /* 38 bytes = 20 bytes id + 16 bytes ipv6 address + 2 bytes port */
389 node_byte_length = 38;
390 }
391
392 for( ; string_len>=node_byte_length; string_len-=node_byte_length, offset+=node_byte_length )
393 {
394 node_index += 1;
395
396 node_ti = proto_tree_add_item( sub_tree, hf_bt_dht_node, tvb, offset, node_byte_length, ENC_NA0x00000000);
397 proto_item_append_text(node_ti, " %d", node_index);
398 node_tree = proto_item_add_subtree( node_ti, ett_bt_dht_peers);
399
400 proto_tree_add_item( node_tree, hf_bt_dht_id, tvb, offset, 20, ENC_NA0x00000000);
401 proto_item_append_text(node_ti, " (id: %s", tvb_bytes_to_str(pinfo->pool, tvb, offset, 20));
402
403 if ( is_ipv6 )
404 {
405 proto_tree_add_item( node_tree, hf_ip6, tvb, offset+20, 16, ENC_NA0x00000000);
406 proto_item_append_text(node_ti, ", IPv6/Port: [%s]", tvb_ip6_to_str(pinfo->pool, tvb, offset+20)tvb_address_to_str(pinfo->pool, tvb, AT_IPv6, offset+20));
407
408 proto_tree_add_item( node_tree, hf_port, tvb, offset+36, 2, ENC_BIG_ENDIAN0x00000000);
409 proto_item_append_text(node_ti, ":%u)", tvb_get_ntohs( tvb, offset+36 ));
410 }
411 else
412 {
413 proto_tree_add_item( node_tree, hf_ip, tvb, offset+20, 4, ENC_BIG_ENDIAN0x00000000);
414 proto_item_append_text(node_ti, ", IPv4/Port: %s", tvb_ip_to_str(pinfo->pool, tvb, offset+20)tvb_address_to_str(pinfo->pool, tvb, AT_IPv4, offset+20));
415
416 proto_tree_add_item( node_tree, hf_port, tvb, offset+24, 2, ENC_BIG_ENDIAN0x00000000);
417 proto_item_append_text(node_ti, ":%u)", tvb_get_ntohs( tvb, offset+24 ));
418 }
419 }
420
421 if( string_len>0 )
422 {
423 proto_tree_add_item( tree, hf_truncated_data, tvb, offset, string_len, ENC_NA0x00000000 );
424 offset += string_len;
425 }
426 proto_item_set_text( ti, "%s: %d nodes", label, node_index );
427 col_append_fstr( pinfo->cinfo, COL_INFO, " Nodes=%d", node_index );
428 *result = wmem_strdup_printf(pinfo->pool, "%d", node_index);
429
430 return offset;
431}
432
433static int
434// NOLINTNEXTLINE(misc-no-recursion)
435dissect_bencoded_dict_entry(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char **key)
436{
437 proto_item *ti;
438 proto_tree *sub_tree;
439 bool_Bool tohex;
440 const char *val;
441 unsigned orig_offset = offset;
442
443 val = NULL((void*)0);
444
445 ti = proto_tree_add_item( tree, hf_bencoded_dict_entry, tvb, offset, 0, ENC_NA0x00000000 );
446 sub_tree = proto_item_add_subtree( ti, ett_bencoded_dict_entry);
447
448 /* dissect the key, it must be a string */
449 offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, key, false0, "Key" );
15
←
Calling 'dissect_bencoded_string'
→
24
←
Returning from 'dissect_bencoded_string'
→
450 if (offset == 0)
25
←
Assuming 'offset' is not equal to 0
→
26
←
Taking false branch
→
451 {
452 proto_tree_add_expert_format(sub_tree, pinfo, &ei_int_string, tvb, offset, -1, "Invalid string for Key");
453 return 0;
454 }
455
456 if (tvb_captured_length_remaining(tvb, offset) == 0)
27
←
Assuming the condition is false
→
28
←
Taking false branch
→
457 return 0;
458
459 /* If it is a dict, then just do recursion */
460 switch( tvb_get_uint8(tvb,offset) )
29
←
Control jumps to 'case 105:' at line 478
→
461 {
462 case 'd':
463 offset = dissect_bencoded_dict( tvb, pinfo, sub_tree, offset, "Value" );
464 val = dict_str;
465 break;
466 case 'l':
467 if( strcmp(*key,"e")==0 )
468 offset = dissect_bt_dht_error( tvb, pinfo, sub_tree, offset, &val, "Value" );
469 else if( strcmp(*key,"values")==0 )
470 offset = dissect_bt_dht_values( tvb, pinfo, sub_tree, offset, &val, "Value" );
471 /* other unfamiliar lists */
472 else
473 {
474 offset = dissect_bencoded_list( tvb, pinfo, sub_tree, offset, "Value" );
475 val = list_str;
476 }
477 break;
478 case 'i':
479 offset = dissect_bencoded_int( tvb, pinfo, sub_tree, offset, &val, "Value" );
480 break;
481 /* it's a string */
482 default:
483 /* special process */
484 if( strcmp(*key,"nodes")==0 )
485 {
486 offset = dissect_bt_dht_nodes( tvb, pinfo, sub_tree, offset, &val, "Value", 0 );
487 }
488 else if( strcmp(*key,"nodes6")==0 )
489 {
490 offset = dissect_bt_dht_nodes( tvb, pinfo, sub_tree, offset, &val, "Value", 1 );
491 }
492 else if( strcmp(*key,"ip")==0 )
493 {
494 /*
495 * BEP 42 DHT Security extension
496 * https://www.bittorrent.org/beps/bep_0042.html
497 * https://www.rasterbar.com/products/libtorrent/dht_sec.html
498 */
499
500 unsigned len;
501 int old_offset = offset;
502 if (!bencoded_string_length(pinfo, tvb, &offset, &len)) {
503 proto_tree_add_expert_format(sub_tree, pinfo, &ei_int_string, tvb, offset, -1, "Invalid string for value");
504 return 0;
505 }
506
507 if(len == 6) {
508 proto_tree_add_item(sub_tree, hf_ip, tvb, offset, 4, ENC_BIG_ENDIAN0x00000000);
509 val = tvb_ip_to_str(pinfo->pool, tvb, offset)tvb_address_to_str(pinfo->pool, tvb, AT_IPv4, offset);
510 offset += 4;
511 proto_tree_add_item(sub_tree, hf_port, tvb, offset, 2, ENC_BIG_ENDIAN0x00000000);
512 offset += 2;
513 }
514 else if (len == 18)
515 {
516 proto_tree_add_item(sub_tree, hf_ip6, tvb, offset, 16, ENC_NA0x00000000);
517 val = tvb_ip6_to_str(pinfo->pool, tvb, offset)tvb_address_to_str(pinfo->pool, tvb, AT_IPv6, offset);
518 offset += 16;
519
520 proto_tree_add_item(sub_tree, hf_port, tvb, offset, 2, ENC_BIG_ENDIAN0x00000000);
521 offset += 2;
522 }
523 else {
524 offset = dissect_bencoded_string( tvb, pinfo, sub_tree, old_offset, &val, true1, "Value" );
525 }
526 }
527 else
528 {
529 /* some need to return hex string */
530 tohex = strcmp(*key,"id")==0 || strcmp(*key,"target")==0
531 || strcmp(*key,"info_hash")==0 || strcmp(*key,"t")==0
532 || strcmp(*key,"v")==0 || strcmp(*key,"token")==0;
533 offset = dissect_bencoded_string( tvb, pinfo, sub_tree, offset, &val, tohex, "Value" );
534 }
535 }
536
537 if (offset == 0)
30
←
 Execution continues on line 537
→
31
←
Assuming 'offset' is not equal to 0
→
538 {
539 proto_tree_add_expert_format(sub_tree, pinfo, &ei_int_string, tvb, offset, -1, "Invalid string for value");
540 return 0;
541 }
542
543 if(*key && strcmp(*key,"q")==0 && strlen(val)>1 )
32
←
Assuming the condition is false
→
544 col_prepend_fstr(pinfo->cinfo, COL_INFO, "%c%s", g_ascii_toupper(val[0]), val + 1);
545 if(*key && strcmp(*key,"r")==0 )
546 col_prepend_fstr(pinfo->cinfo, COL_INFO, "Response");
547 if(*key && strcmp(*key,"e")==0 )
548 col_prepend_fstr(pinfo->cinfo, COL_INFO, "Error");
549 if(*key && (strcmp(*key,"info_hash")==0 || strcmp(*key,"target")==0) )
550 col_append_fstr(pinfo->cinfo, COL_INFO, " %c%s=%s", g_ascii_toupper((*key)[0]), *key + 1, val);
551
552 const char * printable_key = *key;
553 if(key
32.1
'key' is non-null
 && strlen(*key)==1 )
33
←
Null pointer passed to 1st parameter expecting 'nonnull'
554 printable_key = val_to_str_const( (*key)[0], short_key_name_value_string, *key );
555 if(val && strlen(val)==1 )
556 val = val_to_str_const( val[0], short_val_name_value_string, val );
557
558 proto_item_set_text( ti, "%s: %s", printable_key, val );
559 proto_item_set_len( ti, offset-orig_offset );
560
561 return offset;
562}
563
564/* dict = d...e */
565static int
566// NOLINTNEXTLINE(misc-no-recursion)
567dissect_bencoded_dict(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned offset, const char *label )
568{
569 proto_item *ti;
570 proto_tree *sub_tree;
571 unsigned orig_offset = offset;
572
573 /* the shortest valid dictionary is "de", so we need at least 2 bytes */
574 if (tvb_captured_length_remaining(tvb, offset) < 2)
5
←
Assuming the condition is false
→
6
←
Taking false branch
→
575 return 0;
576
577 if(offset
6.1
'offset' is equal to 0
 == 0)
7
←
Taking true branch
→
578 {
579 ti = proto_tree_add_item(tree, proto_bt_dht, tvb, 0, -1, ENC_NA0x00000000);
580 sub_tree = proto_item_add_subtree(ti, ett_bt_dht);
581 }
582 else
583 {
584 ti = proto_tree_add_none_format( tree, hf_bencoded_dict, tvb, offset, -1, "%s: Dictionary...", label );
585 sub_tree = proto_item_add_subtree( ti, ett_bencoded_dict);
586 }
587
588 if (tvb_get_uint8(tvb, offset) != 'd')
8
←
Assuming the condition is false
→
9
←
Taking false branch
→
589 return 0;
590 offset += 1;
591
592 const char * prev_key = NULL((void*)0);
593 unsigned prev_key_offset = 0;
594 while (tvb_captured_length_remaining(tvb, offset) > 0) {
10
←
Assuming the condition is true
→
11
←
Loop condition is true. Entering loop body
→
595 if (tvb_get_uint8(tvb, offset) == 'e')
12
←
Assuming the condition is false
→
13
←
Taking false branch
→
596 break;
597
598 const char * key = NULL((void*)0);
599 const unsigned entry_start = offset;
600 offset = dissect_bencoded_dict_entry( tvb, pinfo, sub_tree, offset, &key );
14
←
Calling 'dissect_bencoded_dict_entry'
→
601 if (offset == 0)
602 {
603 proto_tree_add_expert(sub_tree, pinfo, &ei_int_string, tvb, offset, -1);
604 return 0;
605 }
606
607 if (prev_key != NULL((void*)0) && key != NULL((void*)0)) {
608 const int ordering = strcmp(key, prev_key);
609 if (ordering < 0) {
610 proto_tree_add_expert(
611 sub_tree, pinfo, &ei_unsorted_dict_keys, tvb, prev_key_offset, offset - prev_key_offset);
612 } else if (ordering == 0) {
613 proto_tree_add_expert(
614 sub_tree, pinfo, &ei_duplicate_dict_keys, tvb, prev_key_offset, offset - prev_key_offset);
615 }
616 }
617
618 prev_key = key;
619 prev_key_offset = entry_start;
620 }
621
622 if (tvb_captured_length_remaining(tvb, offset) == 0)
623 return 0;
624
625 proto_tree_add_item(sub_tree, hf_bencoded_list_terminator, tvb, offset, 1, ENC_ASCII0x00000000);
626 offset += 1;
627 proto_item_set_len( ti, offset-orig_offset );
628
629 return offset;
630}
631
632static bool_Bool
633test_bt_dht(packet_info *pinfo _U___attribute__((unused)), tvbuff_t *tvb, int offset, void *data _U___attribute__((unused)))
634{
635
636 /* The DHT KRPC protocol sends packets that are bencoded dictionaries.
637 * Bencoded dictionaries always have the keys in sorted (raw string)
638 * order. There are three possible message types, query, which has "a" and
639 * "q" keys that map to dictionaries, response, which has an "r" key
640 * that maps to a dictionary, and error, which has an "e" key that maps
641 * to a list.
642 *
643 * Conveniently, those keys appear in sort order before all other possible
644 * top level keys, with the exception of the "ip" key added in BEP-0042.
645 *
646 * Thus, there are only four possible initial sets of bytes, corresponding
647 * to beginning with an "a" dictionary, "r" dictionary, "ip" string, or an
648 * "e" list.
649 */
650
651 if (tvb_captured_length_remaining(tvb, offset) < DHT_MIN_LEN5)
652 return false0;
653
654 if (tvb_memeql(tvb, offset, (const uint8_t*)"d1:ad", 5) == 0) {
655 return true1;
656 } else if (tvb_memeql(tvb, offset, (const uint8_t*)"d1:rd", 5) == 0) {
657 return true1;
658 } else if (tvb_memeql(tvb, offset, (const uint8_t*)"d2:ip", 5) == 0) {
659 return true1;
660 } else if (tvb_memeql(tvb, offset, (const uint8_t*)"d1:el", 5) == 0) {
661 return true1;
662 }
663
664 return false0;
665}
666
667static int
668dissect_bt_dht(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
669{
670 /* BitTorrent clients use the same UDP connection for DHT as for uTP.
671 * So even if this has been set as the dissector for this conversation
672 * or port, test it and reject it if not BT-DHT in order to give other
673 * dissectors, especially BT-uTP, a chance.
674 */
675 if (!test_bt_dht(pinfo, tvb, 0, data)) {
3
←
Taking false branch
→
676 return 0;
677 }
678
679 col_set_str(pinfo->cinfo, COL_PROTOCOL, "BT-DHT");
680 col_clear(pinfo->cinfo, COL_INFO);
681
682 /* XXX: There is a separate "bencode" dissector. Would it be possible
683 * to use it, at least to move some functions into a shared header?
684 * DHT has some keys with special meanings, and some values that
685 * are supposed to be interpreted specially (e.g., IP/port combinations),
686 * so maybe it's more trouble than it's worth.
687 */
688 return dissect_bencoded_dict(tvb, pinfo, tree, 0, "BitTorrent DHT Protocol");
4
←
Calling 'dissect_bencoded_dict'
→
689}
690
691static
692bool_Bool dissect_bt_dht_heur (tvbuff_t *tvb, packet_info *pinfo,
693 proto_tree *tree, void *data)
694{
695 conversation_t *conversation;
696
697 if (!test_bt_dht(pinfo, tvb, 0, data)) {
1
Taking false branch
→
698 return false0;
699 }
700
701 conversation = find_or_create_conversation(pinfo);
702 conversation_set_dissector_from_frame_number(conversation, pinfo->num, bt_dht_handle);
703
704 dissect_bt_dht(tvb, pinfo, tree, NULL((void*)0));
2
←
Calling 'dissect_bt_dht'
→
705 return true1;
706}
707
708void
709proto_register_bt_dht(void)
710{
711 expert_module_t* expert_bt_dht;
712
713 static hf_register_info hf[] = {
714 { &hf_bencoded_string,
715 { "String", "bt-dht.bencoded.string",
716 FT_STRING, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
717 },
718 { &hf_bencoded_list,
719 { "List", "bt-dht.bencoded.list",
720 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
721 },
722 { &hf_bencoded_int,
723 { "Int", "bt-dht.bencoded.int",
724 FT_STRING, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
725 },
726 { &hf_bencoded_dict,
727 { "Dictionary", "bt-dht.bencoded.dict",
728 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
729 },
730 { &hf_bencoded_dict_entry,
731 { "Dictionary Entry", "bt-dht.bencoded.dict_entry",
732 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
733 },
734 { &hf_bencoded_list_terminator,
735 { "Terminator", "bt-dht.bencoded.list.terminator",
736 FT_STRING, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
737 },
738 { &hf_bt_dht_error,
739 { "Error", "bt-dht.error",
740 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
741 },
742 { &hf_bt_dht_peer,
743 { "Peer", "bt-dht.peer",
744 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
745 },
746 { &hf_bt_dht_peers,
747 { "Peers", "bt-dht.peers",
748 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
749 },
750 { &hf_bt_dht_node,
751 { "Node", "bt-dht.node",
752 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
753 },
754 { &hf_bt_dht_nodes,
755 { "Nodes", "bt-dht.nodes",
756 FT_NONE, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
757 },
758 { &hf_bt_dht_id,
759 { "ID", "bt-dht.id",
760 FT_BYTES, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
761 },
762 { &hf_ip,
763 { "IP", "bt-dht.ip",
764 FT_IPv4, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
765 },
766 { &hf_ip6,
767 { "IP", "bt-dht.ip6",
768 FT_IPv6, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
769 },
770 { &hf_port,
771 { "Port", "bt-dht.port",
772 FT_UINT16, BASE_DEC, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
773 },
774 { &hf_truncated_data,
775 { "Truncated data", "bt-dht.truncated_data",
776 FT_BYTES, BASE_NONE, NULL((void*)0), 0x0, NULL((void*)0), HFILL-1, 0, HF_REF_TYPE_NONE, -1, ((void*)0) }
777 }
778 };
779
780 static ei_register_info ei[] = {
781 { &ei_int_string, { "bt-dht.invalid_string", PI_MALFORMED0x07000000, PI_ERROR0x00800000,
782 "String must contain an integer", EXPFILL0, ((void*)0), 0, {0, {((void*)0), ((void*)0), FT_NONE, BASE_NONE
, ((void*)0), 0, ((void*)0), -1, 0, HF_REF_TYPE_NONE, -1, ((void
*)0)}} }},
783 { &ei_invalid_len, { "bt-dht.invalid_length", PI_MALFORMED0x07000000, PI_ERROR0x00800000,
784 "Invalid length", EXPFILL0, ((void*)0), 0, {0, {((void*)0), ((void*)0), FT_NONE, BASE_NONE
, ((void*)0), 0, ((void*)0), -1, 0, HF_REF_TYPE_NONE, -1, ((void
*)0)}} }},
785 { &ei_duplicate_dict_keys, { "bt-dht.bencoding.dict_duplicate_key", PI_PROTOCOL0x09000000, PI_WARN0x00600000,
786 "Dictionary has duplicate keys", EXPFILL0, ((void*)0), 0, {0, {((void*)0), ((void*)0), FT_NONE, BASE_NONE
, ((void*)0), 0, ((void*)0), -1, 0, HF_REF_TYPE_NONE, -1, ((void
*)0)}} }},
787 { &ei_unsorted_dict_keys, { "bt-dht.bencoding.dict_out_of_order", PI_PROTOCOL0x09000000, PI_CHAT0x00200000,
788 "Dictionary keys are not in sorted order", EXPFILL0, ((void*)0), 0, {0, {((void*)0), ((void*)0), FT_NONE, BASE_NONE
, ((void*)0), 0, ((void*)0), -1, 0, HF_REF_TYPE_NONE, -1, ((void
*)0)}} }},
789 };
790
791 /* Setup protocol subtree array */
792 static int *ett[] = {
793 &ett_bt_dht,
794 &ett_bencoded_list,
795 &ett_bencoded_dict,
796 &ett_bt_dht_error,
797 &ett_bt_dht_peers,
798 &ett_bt_dht_nodes,
799 &ett_bencoded_dict_entry
800 };
801
802 module_t *bt_dht_module;
803
804 proto_bt_dht = proto_register_protocol ("BitTorrent DHT Protocol", "BT-DHT", "bt-dht");
805
806 bt_dht_module = prefs_register_protocol(proto_bt_dht, NULL((void*)0));
807 prefs_register_obsolete_preference(bt_dht_module, "enable");
808
809 proto_register_field_array(proto_bt_dht, hf, array_length(hf)(sizeof (hf) / sizeof (hf)[0]));
810 proto_register_subtree_array(ett, array_length(ett)(sizeof (ett) / sizeof (ett)[0]));
811
812 expert_bt_dht = expert_register_protocol(proto_bt_dht);
813 expert_register_field_array(expert_bt_dht, ei, array_length(ei)(sizeof (ei) / sizeof (ei)[0]));
814
815 bt_dht_handle = register_dissector("bt-dht", dissect_bt_dht, proto_bt_dht);
816}
817
818void
819proto_reg_handoff_bt_dht(void)
820{
821 heur_dissector_add("udp", dissect_bt_dht_heur, "BitTorrent DHT over UDP", "bittorrent_dht_udp", proto_bt_dht, HEURISTIC_ENABLE);
822
823 // If this is ever streamed (transported over TCP) we need to add recursion checks.
824 dissector_add_for_decode_as_with_preference("udp.port", bt_dht_handle);
825}
826
827/*
828 * Editor modelines
829 *
830 * Local Variables:
831 * c-basic-offset: 2
832 * tab-width: 8
833 * indent-tabs-mode: nil
834 * End:
835 *
836 * ex: set shiftwidth=2 tabstop=8 expandtab:
837 * :indentSize=2:tabSize=8:noTabs=true:
838 */