FD.io VPP  v18.07.1-19-g511ce25
Vector Packet Processing
pcap.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2015 Cisco and/or its affiliates.
3  * Licensed under the Apache License, Version 2.0 (the "License");
4  * you may not use this file except in compliance with the License.
5  * You may obtain a copy of the License at:
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software
10  * distributed under the License is distributed on an "AS IS" BASIS,
11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  * See the License for the specific language governing permissions and
13  * limitations under the License.
14  */
15 /*
16  * pcap.c: libpcap packet capture format
17  *
18  * Copyright (c) 2008 Eliot Dresselhaus
19  *
20  * Permission is hereby granted, free of charge, to any person obtaining
21  * a copy of this software and associated documentation files (the
22  * "Software"), to deal in the Software without restriction, including
23  * without limitation the rights to use, copy, modify, merge, publish,
24  * distribute, sublicense, and/or sell copies of the Software, and to
25  * permit persons to whom the Software is furnished to do so, subject to
26  * the following conditions:
27  *
28  * The above copyright notice and this permission notice shall be
29  * included in all copies or substantial portions of the Software.
30  *
31  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
32  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
33  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
34  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
35  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
36  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
37  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
38  */
39 
40 #include <vnet/unix/pcap.h>
41 #include <sys/fcntl.h>
42 
43 /**
44  * @file
45  * @brief PCAP function.
46  *
47  * Usage:
48  *
49  * <code><pre>
50  * \#include <vnet/unix/pcap.h>
51  *
52  * static pcap_main_t pcap = {
53  * .file_name = "/tmp/ip4",
54  * .n_packets_to_capture = 2,
55  * .packet_type = PCAP_PACKET_TYPE_ip,
56  * };
57  * </pre></code>
58  *
59  * To add a buffer:
60  *
61  * <code><pre>pcap_add_buffer (&pcap, vm, pi0, 128);</pre></code>
62  *
63  * File will be written after @c n_packets_to_capture or call to pcap_write (&amp;pcap).
64  *
65 */
66 
67 /**
68  * @brief Close PCAP file
69  *
70  * @return rc - clib_error_t
71  *
72  */
75 {
76  close (pm->file_descriptor);
77  pm->flags &= ~PCAP_MAIN_INIT_DONE;
78  pm->file_descriptor = -1;
79  return 0;
80 }
81 
82 /**
83  * @brief Write PCAP file
84  *
85  * @return rc - clib_error_t
86  *
87  */
90 {
91  clib_error_t *error = 0;
92 
93  if (!(pm->flags & PCAP_MAIN_INIT_DONE))
94  {
96  int n;
97 
98  if (!pm->file_name)
99  pm->file_name = "/tmp/vnet.pcap";
100 
101  pm->file_descriptor =
102  open (pm->file_name, O_CREAT | O_TRUNC | O_WRONLY, 0664);
103  if (pm->file_descriptor < 0)
104  {
105  error =
106  clib_error_return_unix (0, "failed to open `%s'", pm->file_name);
107  goto done;
108  }
109 
110  pm->flags |= PCAP_MAIN_INIT_DONE;
111  pm->n_packets_captured = 0;
112  pm->n_pcap_data_written = 0;
113 
114  /* Write file header. */
115  memset (&fh, 0, sizeof (fh));
116  fh.magic = 0xa1b2c3d4;
117  fh.major_version = 2;
118  fh.minor_version = 4;
119  fh.time_zone = 0;
120  fh.max_packet_size_in_bytes = 1 << 16;
121  fh.packet_type = pm->packet_type;
122  n = write (pm->file_descriptor, &fh, sizeof (fh));
123  if (n != sizeof (fh))
124  {
125  if (n < 0)
126  error =
127  clib_error_return_unix (0, "write file header `%s'",
128  pm->file_name);
129  else
130  error =
131  clib_error_return (0, "short write of file header `%s'",
132  pm->file_name);
133  goto done;
134  }
135  }
136 
137  while (vec_len (pm->pcap_data) > pm->n_pcap_data_written)
138  {
139  int n = vec_len (pm->pcap_data) - pm->n_pcap_data_written;
140 
141  n = write (pm->file_descriptor,
143  n);
144 
145  if (n < 0 && unix_error_is_fatal (errno))
146  {
147  error = clib_error_return_unix (0, "write `%s'", pm->file_name);
148  goto done;
149  }
150  pm->n_pcap_data_written += n;
151  }
152 
153  if (pm->n_pcap_data_written >= vec_len (pm->pcap_data))
154  {
156  pm->n_pcap_data_written = 0;
157  }
158 
160  pcap_close (pm);
161 
162 done:
163  if (error)
164  {
165  if (pm->file_descriptor >= 0)
166  close (pm->file_descriptor);
167  }
168  return error;
169 }
170 
171 /**
172  * @brief Read PCAP file
173  *
174  * @return rc - clib_error_t
175  *
176  */
177 clib_error_t *
179 {
180  clib_error_t *error = 0;
181  int fd, need_swap, n;
184 
185  fd = open (pm->file_name, O_RDONLY);
186  if (fd < 0)
187  {
188  error = clib_error_return_unix (0, "open `%s'", pm->file_name);
189  goto done;
190  }
191 
192  if (read (fd, &fh, sizeof (fh)) != sizeof (fh))
193  {
194  error =
195  clib_error_return_unix (0, "read file header `%s'", pm->file_name);
196  goto done;
197  }
198 
199  need_swap = 0;
200  if (fh.magic == 0xd4c3b2a1)
201  {
202  need_swap = 1;
203 #define _(t,f) fh.f = clib_byte_swap_##t (fh.f);
205 #undef _
206  }
207 
208  if (fh.magic != 0xa1b2c3d4)
209  {
210  error = clib_error_return (0, "bad magic `%s'", pm->file_name);
211  goto done;
212  }
213 
214  pm->min_packet_bytes = 0;
215  pm->max_packet_bytes = 0;
216  while ((n = read (fd, &ph, sizeof (ph))) != 0)
217  {
218  u8 *data;
219  u64 timestamp;
220  u32 timestamp_sec;
221  u32 timestamp_usec;
222 
223  if (need_swap)
224  {
225 #define _(t,f) ph.f = clib_byte_swap_##t (ph.f);
227 #undef _
228  }
229 
230  data = vec_new (u8, ph.n_bytes_in_packet);
231  if (read (fd, data, ph.n_packet_bytes_stored_in_file) !=
232  ph.n_packet_bytes_stored_in_file)
233  {
234  error = clib_error_return (0, "short read `%s'", pm->file_name);
235  goto done;
236  }
237 
238  if (vec_len (pm->packets_read) == 0)
239  pm->min_packet_bytes = pm->max_packet_bytes = ph.n_bytes_in_packet;
240  else
241  {
242  pm->min_packet_bytes =
243  clib_min (pm->min_packet_bytes, ph.n_bytes_in_packet);
244  pm->max_packet_bytes =
245  clib_max (pm->max_packet_bytes, ph.n_bytes_in_packet);
246  }
247 
248  timestamp_sec = ph.time_in_sec;
249  timestamp_usec = ph.time_in_usec;
250  timestamp = ((u64) timestamp_sec) * 1000000 + (u64) timestamp_usec;
251  vec_add1 (pm->packets_read, data);
252  vec_add1 (pm->timestamps, timestamp);
253  }
254 
255 done:
256  if (fd >= 0)
257  close (fd);
258  return error;
259 
260 }
261 
262 /*
263  * fd.io coding-style-patch-verification: ON
264  *
265  * Local Variables:
266  * eval: (c-set-style "gnu")
267  * End:
268  */
char * file_name
File name of pcap output.
Definition: pcap.h:127
#define clib_min(x, y)
Definition: clib.h:289
u32 flags
flags
Definition: pcap.h:139
int file_descriptor
File descriptor for reading/writing.
Definition: pcap.h:143
u32 n_packets_to_capture
Number of packets to capture.
Definition: pcap.h:130
unsigned long u64
Definition: types.h:89
PCAP utility definitions.
u32 max_packet_bytes
Definition: pcap.h:158
#define vec_add1(V, E)
Add 1 element to end of vector (unspecified alignment).
Definition: vec.h:523
unsigned char u8
Definition: types.h:56
#define vec_reset_length(v)
Reset vector length to zero NULL-pointer tolerant.
PCAP main state data structure.
Definition: pcap.h:124
#define vec_new(T, N)
Create new vector of given type and length (unspecified alignment, no header).
Definition: vec.h:309
#define vec_elt_at_index(v, i)
Get vector value at index i checking that i is in bounds.
#define clib_error_return(e, args...)
Definition: error.h:99
#define foreach_pcap_packet_header
Definition: pcap.h:100
u32 n_pcap_data_written
Bytes written.
Definition: pcap.h:146
unsigned int u32
Definition: types.h:88
u8 * pcap_data
Vector of pcap data.
Definition: pcap.h:149
#define clib_error_return_unix(e, args...)
Definition: error.h:102
clib_error_t * pcap_read(pcap_main_t *pm)
Read PCAP file.
Definition: pcap.c:178
clib_error_t * pcap_close(pcap_main_t *pm)
Close PCAP file.
Definition: pcap.c:74
clib_error_t * pcap_write(pcap_main_t *pm)
Write PCAP file.
Definition: pcap.c:89
Packet header.
Definition: pcap.h:112
#define PCAP_MAIN_INIT_DONE
Definition: pcap.h:140
static word unix_error_is_fatal(word error)
Definition: error.h:118
#define clib_max(x, y)
Definition: clib.h:282
u32 min_packet_bytes
Min/Max Packet bytes.
Definition: pcap.h:158
u64 * timestamps
Timestamps.
Definition: pcap.h:155
pcap_packet_type_t packet_type
Packet type.
Definition: pcap.h:133
#define vec_len(v)
Number of elements in vector (rvalue-only, NULL tolerant)
File header struct.
Definition: pcap.h:93
u8 ** packets_read
Packets read from file.
Definition: pcap.h:152
u32 n_packets_captured
Number of packets currently captured.
Definition: pcap.h:136
#define foreach_pcap_file_header
Definition: pcap.h:71