1 /* $NetBSD: npfd_log.c,v 1.14 2022/04/30 13:20:09 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2015 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Mindaugas Rasiukevicius.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __RCSID("$NetBSD: npfd_log.c,v 1.14 2022/04/30 13:20:09 christos Exp $");
34
35 #include <sys/types.h>
36 #include <sys/param.h>
37 #include <sys/stat.h>
38
39 #include <net/if.h>
40
41 #include <stdio.h>
42 #include <string.h>
43 #include <err.h>
44 #include <inttypes.h>
45 #include <limits.h>
46 #include <stdlib.h>
47 #include <unistd.h>
48 #include <syslog.h>
49 #include <stdbool.h>
50
51 #include <pcap/pcap.h>
52 #include "npfd.h"
53
54 struct npfd_log {
55 char ifname[IFNAMSIZ];
56 char path[MAXPATHLEN];
57 char *filter;
58 int snaplen;
59 pcap_t *pcap;
60 pcap_dumper_t *dumper;
61 };
62
63 static void
npfd_log_setfilter(npfd_log_t * ctx)64 npfd_log_setfilter(npfd_log_t *ctx)
65 {
66 struct bpf_program bprog;
67
68 if (ctx->filter == NULL)
69 return;
70
71 if (pcap_compile(ctx->pcap, &bprog, ctx->filter, 1, 0) == -1)
72 errx(EXIT_FAILURE, "pcap_compile failed for `%s': %s",
73 ctx->filter, pcap_geterr(ctx->pcap));
74 if (pcap_setfilter(ctx->pcap, &bprog) == -1)
75 errx(EXIT_FAILURE, "pcap_setfilter failed: %s",
76 pcap_geterr(ctx->pcap));
77 pcap_freecode(&bprog);
78 }
79
80 static FILE *
npfd_log_gethdr(npfd_log_t * ctx,struct pcap_file_header * hdr)81 npfd_log_gethdr(npfd_log_t *ctx, struct pcap_file_header*hdr)
82 {
83 FILE *fp = fopen(ctx->path, "r");
84
85 hdr->magic = 0;
86 if (fp == NULL)
87 return NULL;
88
89 #define TCPDUMP_MAGIC 0xa1b2c3d4
90
91 switch (fread(hdr, sizeof(*hdr), 1, fp)) {
92 case 0:
93 hdr->magic = 0;
94 fclose(fp);
95 return NULL;
96 case 1:
97 if (hdr->magic != TCPDUMP_MAGIC ||
98 hdr->version_major != PCAP_VERSION_MAJOR ||
99 hdr->version_minor != PCAP_VERSION_MINOR ||
100 hdr->sigfigs != (u_int)pcap_get_tstamp_precision(ctx->pcap))
101 goto out;
102 break;
103 default:
104 goto out;
105 }
106
107 return fp;
108 out:
109 fclose(fp);
110 hdr->magic = (uint32_t)-1;
111 return NULL;
112 }
113
114 static int
npfd_log_getsnaplen(npfd_log_t * ctx)115 npfd_log_getsnaplen(npfd_log_t *ctx)
116 {
117 struct pcap_file_header hdr;
118 FILE *fp = npfd_log_gethdr(ctx, &hdr);
119 if (fp == NULL)
120 return hdr.magic == (uint32_t)-1 ? -1 : 0;
121 fclose(fp);
122 return hdr.snaplen;
123 }
124
125 static int
npfd_log_validate(npfd_log_t * ctx)126 npfd_log_validate(npfd_log_t *ctx)
127 {
128 struct pcap_file_header hdr;
129 FILE *fp = npfd_log_gethdr(ctx, &hdr);
130 size_t o, no;
131
132 if (fp == NULL) {
133 if (hdr.magic == 0)
134 return 0;
135 goto rename;
136 }
137
138 struct stat st;
139 if (fstat(fileno(fp), &st) == -1)
140 goto rename;
141
142 size_t count = 0;
143 for (o = sizeof(hdr);; count++) {
144 struct {
145 uint32_t sec;
146 uint32_t usec;
147 uint32_t caplen;
148 uint32_t len;
149 } pkt;
150 switch (fread(&pkt, sizeof(pkt), 1, fp)) {
151 case 0:
152 syslog(LOG_INFO, "%zu packets read from `%s'", count,
153 ctx->path);
154 fclose(fp);
155 return hdr.snaplen;
156 case 1:
157 no = o + sizeof(pkt) + pkt.caplen;
158 if (pkt.caplen > hdr.snaplen)
159 goto fix;
160 if (no > (size_t)st.st_size)
161 goto fix;
162 if (fseeko(fp, pkt.caplen, SEEK_CUR) != 0)
163 goto fix;
164 o = no;
165 break;
166 default:
167 goto fix;
168 }
169 }
170
171 fix:
172 fclose(fp);
173 no = st.st_size - o;
174 syslog(LOG_INFO, "%zu packets read from `%s', %zu extra bytes",
175 count, ctx->path, no);
176 if (no < 10240) {
177 syslog(LOG_WARNING,
178 "Incomplete last packet in `%s', truncating",
179 ctx->path);
180 if (truncate(ctx->path, (off_t)o) == -1) {
181 syslog(LOG_ERR, "Cannot truncate `%s': %m", ctx->path);
182 goto rename;
183 }
184 } else {
185 syslog(LOG_ERR, "Corrupt file `%s'", ctx->path);
186 goto rename;
187 }
188 fclose(fp);
189 return hdr.snaplen;
190 rename:
191 fclose(fp);
192 char tmp[MAXPATHLEN];
193 if (snprintf(tmp, sizeof(tmp), "%s.XXXXXX", ctx->path) > MAXPATHLEN)
194 syslog(LOG_ERR, "Temp file truncated: `%s' does not fit",
195 ctx->path);
196 int fd;
197 if ((fd = mkstemp(tmp)) == -1) {
198 syslog(LOG_ERR, "Can't make temp file `%s': %m", tmp);
199 return -1;
200 }
201 close(fd);
202 if (rename(ctx->path, tmp) == -1) {
203 syslog(LOG_ERR, "Can't rename `%s' to `%s': %m",
204 ctx->path, tmp);
205 return -1;
206 }
207 syslog(LOG_ERR, "Renamed to `%s'", tmp);
208 return 0;
209 }
210
211
212 npfd_log_t *
npfd_log_create(const char * filename,const char * ifname,const char * filter,int snaplen)213 npfd_log_create(const char *filename, const char *ifname, const char *filter,
214 int snaplen)
215 {
216 npfd_log_t *ctx;
217
218 if ((ctx = calloc(1, sizeof(*ctx))) == NULL)
219 err(EXIT_FAILURE, "malloc failed");
220
221 snprintf(ctx->ifname, sizeof(ctx->ifname), "%s", ifname);
222 if (filename == NULL)
223 snprintf(ctx->path, sizeof(ctx->path), NPFD_LOG_PATH "/%s.pcap",
224 ctx->ifname);
225 else
226 snprintf(ctx->path, sizeof(ctx->path), "%s", filename);
227
228 if (filter != NULL) {
229 ctx->filter = strdup(filter);
230 if (ctx->filter == NULL)
231 err(EXIT_FAILURE, "malloc failed");
232 }
233 ctx->snaplen = snaplen;
234
235 /* Open a live capture handle in non-blocking mode. */
236 npfd_log_pcap_reopen(ctx);
237
238 /* Open the log file */
239 npfd_log_file_reopen(ctx, false);
240 return ctx;
241 }
242
243
244 bool
npfd_log_pcap_reopen(npfd_log_t * ctx)245 npfd_log_pcap_reopen(npfd_log_t *ctx)
246 {
247 char errbuf[PCAP_ERRBUF_SIZE];
248 int snaplen = ctx->snaplen;
249 int rc;
250
251 if (ctx->pcap != NULL)
252 pcap_close(ctx->pcap);
253 else
254 syslog(LOG_INFO, "reopening pcap socket");
255
256 ctx->pcap = pcap_create(ctx->ifname, errbuf);
257 if (ctx->pcap == NULL)
258 errx(EXIT_FAILURE, "pcap_create failed: %s", errbuf);
259
260 if (pcap_setnonblock(ctx->pcap, 1, errbuf) == -1)
261 errx(EXIT_FAILURE, "pcap_setnonblock failed: %s", errbuf);
262
263 int sl = npfd_log_getsnaplen(ctx);
264 if (sl == -1)
265 errx(EXIT_FAILURE, "corrupt log file `%s'", ctx->path);
266
267 if (sl != 0 && sl != snaplen) {
268 warnx("Overriding snaplen from %d to %d from `%s'", snaplen,
269 sl, ctx->path);
270 snaplen = sl;
271 }
272
273 if (pcap_set_snaplen(ctx->pcap, snaplen) == -1)
274 errx(EXIT_FAILURE, "pcap_set_snaplen failed: %s",
275 pcap_geterr(ctx->pcap));
276
277 if (pcap_set_timeout(ctx->pcap, 1000) == -1)
278 errx(EXIT_FAILURE, "pcap_set_timeout failed: %s",
279 pcap_geterr(ctx->pcap));
280
281 if ((rc = pcap_activate(ctx->pcap)) != 0) {
282 const char *msg = pcap_geterr(ctx->pcap);
283 if (rc > 0) {
284 warnx("pcap_activate warning: %s", msg);
285 } else {
286 errx(EXIT_FAILURE, "pcap_activate failed: %s", msg);
287 }
288 }
289
290 npfd_log_setfilter(ctx);
291 return true;
292 }
293
294 bool
npfd_log_file_reopen(npfd_log_t * ctx,bool die)295 npfd_log_file_reopen(npfd_log_t *ctx, bool die)
296 {
297 mode_t omask = umask(077);
298
299 if (ctx->dumper)
300 pcap_dump_close(ctx->dumper);
301 /*
302 * Open a log file to write for a given interface and dump there.
303 */
304 switch (npfd_log_validate(ctx)) {
305 case -1:
306 syslog(LOG_ERR, "Giving up");
307 exit(EXIT_FAILURE);
308 /*NOTREACHED*/
309 case 0:
310 ctx->dumper = pcap_dump_open(ctx->pcap, ctx->path);
311 break;
312 default:
313 ctx->dumper = pcap_dump_open_append(ctx->pcap, ctx->path);
314 break;
315 }
316 (void)umask(omask);
317
318 if (ctx->dumper == NULL) {
319 if (die)
320 errx(EXIT_FAILURE, "pcap_dump_open failed for `%s': %s",
321 ctx->path, pcap_geterr(ctx->pcap));
322 syslog(LOG_ERR, "pcap_dump_open failed for `%s': %s",
323 ctx->path, pcap_geterr(ctx->pcap));
324 return false;
325 }
326 return true;
327 }
328
329 void
npfd_log_destroy(npfd_log_t * ctx)330 npfd_log_destroy(npfd_log_t *ctx)
331 {
332 if (ctx->dumper)
333 pcap_dump_close(ctx->dumper);
334 if (ctx->pcap)
335 pcap_close(ctx->pcap);
336 free(ctx);
337 }
338
339 int
npfd_log_getsock(npfd_log_t * ctx)340 npfd_log_getsock(npfd_log_t *ctx)
341 {
342 return pcap_get_selectable_fd(ctx->pcap);
343 }
344
345 void
npfd_log_flush(npfd_log_t * ctx)346 npfd_log_flush(npfd_log_t *ctx)
347 {
348 if (!ctx->dumper)
349 return;
350 if (pcap_dump_flush(ctx->dumper) == -1)
351 syslog(LOG_ERR, "pcap_dump_flush failed for `%s': %m",
352 ctx->path);
353 }
354
355
356 int
npfd_log(npfd_log_t * ctx)357 npfd_log(npfd_log_t *ctx)
358 {
359 pcap_dumper_t *dumper = ctx->dumper;
360
361 return pcap_dispatch(ctx->pcap, PCAP_NPACKETS, pcap_dump,
362 (void *)dumper);
363 }
364
365 void
npfd_log_stats(npfd_log_t * ctx)366 npfd_log_stats(npfd_log_t *ctx)
367 {
368 pcap_t *pcap = ctx->pcap;
369 struct pcap_stat ps;
370
371 if (pcap_stats(pcap, &ps) == -1) {
372 syslog(LOG_ERR, "pcap_stats failed: %s", pcap_geterr(pcap));
373 return;
374 }
375 syslog(LOG_INFO, "packet statistics: %s: %u received, %u dropped",
376 ctx->ifname, ps.ps_recv, ps.ps_drop);
377 }
378