2 * Copyright (c) 2009, 2010, 2012, 2013, 2014, 2015 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include "pcap-file.h"
24 #include "byte-order.h"
26 #include "dp-packet.h"
28 #include "openvswitch/hmap.h"
31 #include "unaligned.h"
33 #include "openvswitch/vlog.h"
35 VLOG_DEFINE_THIS_MODULE(pcap);
38 uint32_t magic_number; /* magic number */
39 uint16_t version_major; /* major version number */
40 uint16_t version_minor; /* minor version number */
41 int32_t thiszone; /* GMT to local correction */
42 uint32_t sigfigs; /* accuracy of timestamps */
43 uint32_t snaplen; /* max length of captured packets */
44 uint32_t network; /* data link type */
46 BUILD_ASSERT_DECL(sizeof(struct pcap_hdr) == 24);
49 uint32_t ts_sec; /* timestamp seconds */
50 uint32_t ts_usec; /* timestamp microseconds */
51 uint32_t incl_len; /* number of octets of packet saved in file */
52 uint32_t orig_len; /* actual length of packet */
54 BUILD_ASSERT_DECL(sizeof(struct pcaprec_hdr) == 16);
57 ovs_pcap_open(const char *file_name, const char *mode)
63 ovs_assert(!strcmp(mode, "rb") ||
64 !strcmp(mode, "wb") ||
67 file = fopen(file_name, mode);
69 VLOG_WARN("%s: failed to open pcap file for %s (%s)", file_name,
70 (mode[0] == 'r' ? "reading"
71 : mode[0] == 'w' ? "writing"
79 error = ovs_pcap_read_header(file);
88 ovs_pcap_write_header(file);
92 if (!fstat(fileno(file), &s) && !s.st_size) {
93 ovs_pcap_write_header(file);
104 ovs_pcap_read_header(FILE *file)
107 if (fread(&ph, sizeof ph, 1, file) != 1) {
108 int error = ferror(file) ? errno : EOF;
109 VLOG_WARN("failed to read pcap header: %s", ovs_retval_to_string(error));
112 if (ph.magic_number != 0xa1b2c3d4 && ph.magic_number != 0xd4c3b2a1) {
113 VLOG_WARN("bad magic 0x%08"PRIx32" reading pcap file "
114 "(expected 0xa1b2c3d4 or 0xd4c3b2a1)", ph.magic_number);
121 ovs_pcap_write_header(FILE *file)
123 /* The pcap reader is responsible for figuring out endianness based on the
124 * magic number, so the lack of htonX calls here is intentional. */
126 ph.magic_number = 0xa1b2c3d4;
127 ph.version_major = 2;
128 ph.version_minor = 4;
132 ph.network = 1; /* Ethernet */
133 ignore(fwrite(&ph, sizeof ph, 1, file));
138 ovs_pcap_read(FILE *file, struct dp_packet **bufp, long long int *when)
140 struct pcaprec_hdr prh;
141 struct dp_packet *buf;
149 if (fread(&prh, sizeof prh, 1, file) != 1) {
152 VLOG_WARN("failed to read pcap record header: %s",
153 ovs_retval_to_string(error));
160 /* Calculate length. */
164 len = uint32_byteswap(len);
166 VLOG_WARN("bad packet length %"PRIuSIZE" or %"PRIu32
168 len, uint32_byteswap(len));
173 /* Calculate time. */
175 uint32_t ts_sec = swap ? uint32_byteswap(prh.ts_sec) : prh.ts_sec;
176 uint32_t ts_usec = swap ? uint32_byteswap(prh.ts_usec) : prh.ts_usec;
177 *when = ts_sec * 1000LL + ts_usec / 1000;
181 buf = dp_packet_new(len);
182 data = dp_packet_put_uninit(buf, len);
183 if (fread(data, len, 1, file) != 1) {
184 int error = ferror(file) ? errno : EOF;
185 VLOG_WARN("failed to read pcap packet: %s",
186 ovs_retval_to_string(error));
187 dp_packet_delete(buf);
195 ovs_pcap_write(FILE *file, struct dp_packet *buf)
197 struct pcaprec_hdr prh;
201 prh.ts_sec = tv.tv_sec;
202 prh.ts_usec = tv.tv_usec;
203 prh.incl_len = dp_packet_size(buf);
204 prh.orig_len = dp_packet_size(buf);
205 ignore(fwrite(&prh, sizeof prh, 1, file));
206 ignore(fwrite(dp_packet_data(buf), dp_packet_size(buf), 1, file));
211 ovs_be32 nw_src, nw_dst;
212 ovs_be16 tp_src, tp_dst;
216 struct hmap_node hmap_node;
219 struct dp_packet payload;
227 tcp_stream_destroy(struct tcp_reader *r, struct tcp_stream *stream)
229 hmap_remove(&r->streams, &stream->hmap_node);
230 dp_packet_uninit(&stream->payload);
234 /* Returns a new data structure for extracting TCP stream data from an
235 * Ethernet packet capture */
237 tcp_reader_open(void)
239 struct tcp_reader *r;
241 r = xmalloc(sizeof *r);
242 hmap_init(&r->streams);
246 /* Closes and frees 'r'. */
248 tcp_reader_close(struct tcp_reader *r)
250 struct tcp_stream *stream, *next_stream;
252 HMAP_FOR_EACH_SAFE (stream, next_stream, hmap_node, &r->streams) {
253 tcp_stream_destroy(r, stream);
255 hmap_destroy(&r->streams);
259 static struct tcp_stream *
260 tcp_stream_lookup(struct tcp_reader *r,
261 const struct tcp_key *key, uint32_t hash)
263 struct tcp_stream *stream;
265 HMAP_FOR_EACH_WITH_HASH (stream, hmap_node, hash, &r->streams) {
266 if (!memcmp(&stream->key, key, sizeof *key)) {
273 static struct tcp_stream *
274 tcp_stream_new(struct tcp_reader *r, const struct tcp_key *key, uint32_t hash)
276 struct tcp_stream *stream;
278 stream = xmalloc(sizeof *stream);
279 hmap_insert(&r->streams, &stream->hmap_node, hash);
280 memcpy(&stream->key, key, sizeof *key);
282 dp_packet_init(&stream->payload, 2048);
286 /* Processes 'packet' through TCP reader 'r'. The caller must have already
287 * extracted the packet's headers into 'flow', using flow_extract().
289 * If 'packet' is a TCP packet, then the reader attempts to reconstruct the
290 * data stream. If successful, it returns an dp_packet that represents the data
291 * stream so far. The caller may examine the data in the dp_packet and pull off
292 * any data that it has fully processed. The remaining data that the caller
293 * does not pull off will be presented again in future calls if more data
294 * arrives in the stream.
296 * Returns null if 'packet' doesn't add new data to a TCP stream. */
298 tcp_reader_run(struct tcp_reader *r, const struct flow *flow,
299 const struct dp_packet *packet)
301 struct tcp_stream *stream;
302 struct tcp_header *tcp;
303 struct dp_packet *payload;
304 unsigned int l7_length;
309 const char *l7 = dp_packet_get_tcp_payload(packet);
311 if (flow->dl_type != htons(ETH_TYPE_IP)
312 || flow->nw_proto != IPPROTO_TCP
316 tcp = dp_packet_l4(packet);
317 flags = TCP_FLAGS(tcp->tcp_ctl);
318 l7_length = (char *) dp_packet_tail(packet) - l7;
319 seq = ntohl(get_16aligned_be32(&tcp->tcp_seq));
322 memset(&key, 0, sizeof key);
323 key.nw_src = flow->nw_src;
324 key.nw_dst = flow->nw_dst;
325 key.tp_src = flow->tp_src;
326 key.tp_dst = flow->tp_dst;
327 hash = hash_bytes(&key, sizeof key, 0);
329 /* Find existing stream or start a new one for a SYN or if there's data. */
330 stream = tcp_stream_lookup(r, &key, hash);
332 if (flags & TCP_SYN || l7_length) {
333 stream = tcp_stream_new(r, &key, hash);
334 stream->seq_no = flags & TCP_SYN ? seq + 1 : seq;
340 payload = &stream->payload;
341 if (flags & TCP_SYN || !stream->seq_no) {
342 dp_packet_clear(payload);
343 stream->seq_no = seq + 1;
345 } else if (flags & (TCP_FIN | TCP_RST)) {
346 tcp_stream_destroy(r, stream);
348 } else if (seq == stream->seq_no) {
349 /* Shift all of the existing payload to the very beginning of the
350 * allocated space, so that we reuse allocated space instead of
351 * continually expanding it. */
352 dp_packet_shift(payload, (char *) dp_packet_base(payload) - (char *) dp_packet_data(payload));
354 dp_packet_put(payload, l7, l7_length);
355 stream->seq_no += l7_length;