Home | History | Annotate | Line # | Download | only in npfd
npfd_log.c revision 1.8 
      1 /*	$NetBSD: npfd_log.c,v 1.8 2017/01/07 16:48:03 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 1.8 2017/01/07 16:48:03 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 <err.h>
     43 #include <inttypes.h>
     44 #include <limits.h>
     45 #include <stdlib.h>
     46 #include <unistd.h>
     47 #include <syslog.h>
     48 #include <stdbool.h>
     49 
     50 #include <pcap/pcap.h>
     51 #include "npfd.h"
     52 
     53 struct npfd_log {
     54 	char ifname[IFNAMSIZ];
     55 	char path[MAXPATHLEN];
     56 	pcap_t *pcap;
     57 	pcap_dumper_t *dumper;
     58 };
     59 
     60 static void
     61 npfd_log_setfilter(npfd_log_t *ctx, const char *filter)
     62 {
     63 	struct bpf_program bprog;
     64 
     65 	if (pcap_compile(ctx->pcap, &bprog, filter, 1, 0) == -1)
     66 		errx(EXIT_FAILURE, "pcap_compile failed for `%s': %s", filter,
     67 		    pcap_geterr(ctx->pcap));
     68 	if (pcap_setfilter(ctx->pcap, &bprog) == -1)
     69 		errx(EXIT_FAILURE, "pcap_setfilter failed: %s",
     70 		    pcap_geterr(ctx->pcap));
     71 	pcap_freecode(&bprog);
     72 }
     73 
     74 static FILE *
     75 npfd_log_gethdr(npfd_log_t *ctx, struct pcap_file_header*hdr)
     76 {
     77 	FILE *fp = fopen(ctx->path, "r");
     78 
     79 	hdr->magic = 0;
     80 	if (fp == NULL)
     81 		return NULL;
     82 
     83 #define TCPDUMP_MAGIC 0xa1b2c3d4
     84 
     85 	switch (fread(hdr, sizeof(*hdr), 1, fp)) {
     86 	case 0:
     87 		hdr->magic = 0;
     88 		fclose(fp);
     89 		return NULL;
     90 	case 1:
     91 		if (hdr->magic != TCPDUMP_MAGIC ||
     92 		    hdr->version_major != PCAP_VERSION_MAJOR ||
     93 		    hdr->version_minor != PCAP_VERSION_MINOR)
     94 			goto out;
     95 		break;
     96 	default:
     97 		goto out;
     98 	}
     99 
    100 	return fp;
    101 out:
    102 	fclose(fp);
    103 	hdr->magic = (uint32_t)-1;
    104 	return NULL;
    105 }
    106 
    107 static int
    108 npfd_log_getsnaplen(npfd_log_t *ctx)
    109 {
    110 	struct pcap_file_header hdr;
    111 	FILE *fp = npfd_log_gethdr(ctx, &hdr);
    112 	if (fp == NULL)
    113 		return hdr.magic == (uint32_t)-1 ? -1 : 0;
    114 	fclose(fp);
    115 	return hdr.snaplen;
    116 }
    117 
    118 static int
    119 npfd_log_validate(npfd_log_t *ctx)
    120 {
    121 	struct pcap_file_header hdr;
    122 	FILE *fp = npfd_log_gethdr(ctx, &hdr);
    123 	size_t o, no;
    124 
    125 	if (fp == NULL) {
    126 		if (hdr.magic == 0)
    127 			return 0;
    128 		goto rename;
    129 	}
    130 
    131 	struct stat st;
    132 	if (fstat(fileno(fp), &st) == -1)
    133 		goto rename;
    134 
    135 	size_t count = 0;
    136 	for (o = sizeof(hdr);; count++) {
    137 		struct {
    138 			uint32_t sec;
    139 			uint32_t usec;
    140 			uint32_t caplen;
    141 			uint32_t len;
    142 		} pkt;
    143 		switch (fread(&pkt, sizeof(pkt), 1, fp)) {
    144 		case 0:
    145 			syslog(LOG_INFO, "%zu packets read from `%s'", count,
    146 			    ctx->path);
    147 			fclose(fp);
    148 			return hdr.snaplen;
    149 		case 1:
    150 			no = o + sizeof(pkt) + pkt.caplen;
    151 			if (pkt.caplen > hdr.snaplen)
    152 				goto fix;
    153 			if (no > (size_t)st.st_size)
    154 				goto fix;
    155 			if (fseeko(fp, pkt.caplen, SEEK_CUR) != 0)
    156 				goto fix;
    157 			o = no;
    158 			break;
    159 		default:
    160 			goto fix;
    161 		}
    162 	}
    163 
    164 fix:
    165 	fclose(fp);
    166 	no = st.st_size - o;
    167 	syslog(LOG_INFO, "%zu packets read from `%s', %zu extra bytes",
    168 	    count, ctx->path, no);
    169 	if (no < 10240) {
    170 		syslog(LOG_WARNING,
    171 		    "Incomplete last packet in `%s', truncating",
    172 		    ctx->path);
    173 		if (truncate(ctx->path, (off_t)o) == -1) {
    174 			syslog(LOG_ERR, "Cannot truncate `%s': %m", ctx->path);
    175 			goto rename;
    176 		}
    177 	} else {
    178 		syslog(LOG_ERR, "Corrupt file `%s'", ctx->path);
    179 		goto rename;
    180 	}
    181 	fclose(fp);
    182 	return hdr.snaplen;
    183 rename:
    184 	fclose(fp);
    185 	char tmp[MAXPATHLEN];
    186 	snprintf(tmp, sizeof(tmp), "%s.XXXXXX", ctx->path);
    187 	int fd;
    188 	if ((fd = mkstemp(tmp)) == -1) {
    189 		syslog(LOG_ERR, "Can't make temp file `%s': %m", tmp);
    190 		return -1;
    191 	}
    192 	close(fd);
    193 	if (rename(ctx->path, tmp) == -1) {
    194 		syslog(LOG_ERR, "Can't rename `%s' to `%s': %m",
    195 		    ctx->path, tmp);
    196 		return -1;
    197 	}
    198 	syslog(LOG_ERR, "Renamed to `%s'", tmp);
    199 	return 0;
    200 }
    201 
    202 
    203 npfd_log_t *
    204 npfd_log_create(const char *filename, const char *ifname, const char *filter,
    205     int snaplen)
    206 {
    207 	npfd_log_t *ctx;
    208 	char errbuf[PCAP_ERRBUF_SIZE];
    209 
    210 	if ((ctx = calloc(1, sizeof(*ctx))) == NULL)
    211 		err(EXIT_FAILURE, "malloc failed");
    212 
    213 	/*
    214 	 * Open a live capture handle in non-blocking mode.
    215 	 */
    216 	snprintf(ctx->ifname, sizeof(ctx->ifname), "%s", ifname);
    217 	ctx->pcap = pcap_create(ctx->ifname, errbuf);
    218 	if (ctx->pcap == NULL)
    219 		errx(EXIT_FAILURE, "pcap_create failed: %s", errbuf);
    220 
    221 	if (pcap_setnonblock(ctx->pcap, 1, errbuf) == -1)
    222 		errx(EXIT_FAILURE, "pcap_setnonblock failed: %s", errbuf);
    223 
    224 	if (filename == NULL)
    225 		snprintf(ctx->path, sizeof(ctx->path), NPFD_LOG_PATH "/%s.pcap",
    226 		    ctx->ifname);
    227 	else
    228 		snprintf(ctx->path, sizeof(ctx->path), "%s", filename);
    229 
    230 	int sl = npfd_log_getsnaplen(ctx);
    231 	if (sl == -1)
    232 		errx(EXIT_FAILURE, "corrupt log file `%s'", ctx->path);
    233 
    234 	if (sl != 0 && sl != snaplen) {
    235 		warnx("Overriding snaplen from %d to %d from `%s'", snaplen,
    236 		    sl, filename);
    237 		snaplen = sl;
    238 	}
    239 
    240 	if (pcap_set_snaplen(ctx->pcap, snaplen) == -1)
    241 		errx(EXIT_FAILURE, "pcap_set_snaplen failed: %s",
    242 		    pcap_geterr(ctx->pcap));
    243 
    244 	if (pcap_set_timeout(ctx->pcap, 1000) == -1)
    245 		errx(EXIT_FAILURE, "pcap_set_timeout failed: %s",
    246 		    pcap_geterr(ctx->pcap));
    247 
    248 	if (pcap_activate(ctx->pcap) == -1)
    249 		errx(EXIT_FAILURE, "pcap_activate failed: %s",
    250 		    pcap_geterr(ctx->pcap));
    251 
    252 	if (filter)
    253 		npfd_log_setfilter(ctx, filter);
    254 
    255 
    256 	npfd_log_reopen(ctx, false);
    257 	return ctx;
    258 }
    259 
    260 bool
    261 npfd_log_reopen(npfd_log_t *ctx, bool die)
    262 {
    263 	mode_t omask = umask(077);
    264 
    265 	if (ctx->dumper)
    266 		pcap_dump_close(ctx->dumper);
    267 	/*
    268 	 * Open a log file to write for a given interface and dump there.
    269 	 */
    270 	switch (npfd_log_validate(ctx)) {
    271 	case -1:
    272 		syslog(LOG_ERR, "Giving up");
    273 		exit(EXIT_FAILURE);
    274 		/*NOTREACHED*/
    275 	case 0:
    276 		ctx->dumper = pcap_dump_open(ctx->pcap, ctx->path);
    277 		break;
    278 	default:
    279 		ctx->dumper = pcap_dump_open_append(ctx->pcap, ctx->path);
    280 		break;
    281 	}
    282 	(void)umask(omask);
    283 
    284 	if (ctx->dumper == NULL) {
    285 		if (die)
    286 			errx(EXIT_FAILURE, "pcap_dump_open failed for `%s': %s",
    287 			    ctx->path, pcap_geterr(ctx->pcap));
    288 		syslog(LOG_ERR, "pcap_dump_open failed for `%s': %s",
    289 		    ctx->path, pcap_geterr(ctx->pcap));
    290 		return false;
    291 	}
    292 	return true;
    293 }
    294 
    295 void
    296 npfd_log_destroy(npfd_log_t *ctx)
    297 {
    298 	if (ctx->dumper)
    299 		pcap_dump_close(ctx->dumper);
    300 	if (ctx->pcap)
    301 		pcap_close(ctx->pcap);
    302 	free(ctx);
    303 }
    304 
    305 int
    306 npfd_log_getsock(npfd_log_t *ctx)
    307 {
    308 	return pcap_get_selectable_fd(ctx->pcap);
    309 }
    310 
    311 void
    312 npfd_log_flush(npfd_log_t *ctx)
    313 {
    314 	if (!ctx->dumper)
    315 		return;
    316 	if (pcap_dump_flush(ctx->dumper) == -1)
    317 		syslog(LOG_ERR, "pcap_dump_flush failed for `%s': %m",
    318 		    ctx->path);
    319 }
    320 
    321 
    322 void
    323 npfd_log(npfd_log_t *ctx)
    324 {
    325 	pcap_dumper_t *dumper = ctx->dumper;
    326 
    327 	pcap_dispatch(ctx->pcap, PCAP_NPACKETS, pcap_dump, (void *)dumper);
    328 }
    329 
    330 void
    331 npfd_log_stats(npfd_log_t *ctx)
    332 {
    333 	pcap_t *pcap = ctx->pcap;
    334 	struct pcap_stat ps;
    335 
    336 	if (pcap_stats(pcap, &ps) == -1) {
    337 		syslog(LOG_ERR, "pcap_stats failed: %s", pcap_geterr(pcap));
    338 		return;
    339 	}
    340 	syslog(LOG_INFO, "packet statistics: %s: %u received, %u dropped",
    341 	    ctx->ifname, ps.ps_recv, ps.ps_drop);
    342 }
    343