forked from osmocom/wireshark
![Guy Harris](/assets/img/avatar_default.png)
bypass Wiretap; that means we don't have to run the packet through wtap_process_pcap_packet() and then undo that conversion in Wiretap if we're just going to write it out, shortening the code path. svn path=/trunk/; revision=17461
187 lines
5.1 KiB
C
187 lines
5.1 KiB
C
/* pcapio.c
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* Our own private code for writing libpcap files when capturing.
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*
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* We have these because we want a way to open a stream for output given
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* only a file descriptor. libpcap 0.9[.x] has "pcap_dump_fopen()", which
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* provides that, but
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*
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* 1) earlier versions of libpcap doesn't have it
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*
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* and
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*
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* 2) WinPcap doesn't have it, because a file descriptor opened
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* by code built for one version of the MSVC++ C library
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* can't be used by library routines built for another version
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* (e.g., threaded vs. unthreaded).
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*
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* Libpcap's pcap_dump() also doesn't return any error indications.
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*
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* $Id$
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*
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* Ethereal - Network traffic analyzer
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* By Gerald Combs <gerald@ethereal.com>
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* Copyright 1998 Gerald Combs
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*
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* Derived from code in the Wiretap Library
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* Copyright (c) 1998 by Gilbert Ramirez <gram@alumni.rice.edu>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdlib.h>
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#include <stdio.h>
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#include <errno.h>
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#include <pcap.h>
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#include <glib.h>
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#include "pcapio.h"
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/* Magic numbers in "libpcap" files.
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"libpcap" file records are written in the byte order of the host that
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writes them, and the reader is expected to fix this up.
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PCAP_MAGIC is the magic number, in host byte order; PCAP_SWAPPED_MAGIC
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is a byte-swapped version of that.
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PCAP_NSEC_MAGIC is for Ulf Lamping's modified "libpcap" format,
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which uses the same common file format as PCAP_MAGIC, but the
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timestamps are saved in nanosecond resolution instead of microseconds.
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PCAP_SWAPPED_NSEC_MAGIC is a byte-swapped version of that. */
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#define PCAP_MAGIC 0xa1b2c3d4
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#define PCAP_SWAPPED_MAGIC 0xd4c3b2a1
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#define PCAP_NSEC_MAGIC 0xa1b23c4d
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#define PCAP_SWAPPED_NSEC_MAGIC 0x4d3cb2a1
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/* "libpcap" file header. */
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struct pcap_hdr {
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guint32 magic; /* magic number */
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guint16 version_major; /* major version number */
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guint16 version_minor; /* minor version number */
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gint32 thiszone; /* GMT to local correction */
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guint32 sigfigs; /* accuracy of timestamps */
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guint32 snaplen; /* max length of captured packets, in octets */
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guint32 network; /* data link type */
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};
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/* "libpcap" record header. */
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struct pcaprec_hdr {
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guint32 ts_sec; /* timestamp seconds */
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guint32 ts_usec; /* timestamp microseconds (nsecs for PCAP_NSEC_MAGIC) */
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guint32 incl_len; /* number of octets of packet saved in file */
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guint32 orig_len; /* actual length of packet */
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};
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/* Returns a FILE * to write to on success, NULL on failure; sets "*err" to
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an error code, or 0 for a short write, on failure */
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FILE *
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libpcap_fdopen(int fd, int linktype, int snaplen, long *bytes_written,
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int *err)
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{
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FILE *fp;
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struct pcap_hdr file_hdr;
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size_t nwritten;
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fp = fdopen(fd, "wb");
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if (fp == NULL) {
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*err = errno;
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return NULL;
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}
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file_hdr.magic = PCAP_MAGIC;
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/* current "libpcap" format is 2.4 */
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file_hdr.version_major = 2;
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file_hdr.version_minor = 4;
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file_hdr.thiszone = 0; /* XXX - current offset? */
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file_hdr.sigfigs = 0; /* unknown, but also apparently unused */
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file_hdr.snaplen = snaplen;
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file_hdr.network = linktype;
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nwritten = fwrite(&file_hdr, 1, sizeof file_hdr, fp);
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if (nwritten != sizeof file_hdr) {
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if (nwritten == 0 && ferror(fp))
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*err = errno;
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else
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*err = 0; /* short write */
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fclose(fp);
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return NULL;
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}
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*bytes_written = sizeof file_hdr;
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return fp;
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}
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/* Write a record for a packet to a dump file.
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Returns TRUE on success, FALSE on failure. */
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gboolean
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libpcap_write_packet(FILE *fp, const struct pcap_pkthdr *phdr, const u_char *pd,
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long *bytes_written, int *err)
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{
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struct pcaprec_hdr rec_hdr;
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size_t nwritten;
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rec_hdr.ts_sec = phdr->ts.tv_sec;
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rec_hdr.ts_usec = phdr->ts.tv_usec;
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rec_hdr.incl_len = phdr->caplen;
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rec_hdr.orig_len = phdr->len;
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nwritten = fwrite(&rec_hdr, 1, sizeof rec_hdr, fp);
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if (nwritten != sizeof rec_hdr) {
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if (nwritten == 0 && ferror(fp))
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*err = errno;
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else
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*err = 0; /* short write */
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return FALSE;
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}
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*bytes_written += sizeof rec_hdr;
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nwritten = fwrite(pd, 1, phdr->caplen, fp);
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if (nwritten != phdr->caplen) {
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if (nwritten == 0 && ferror(fp))
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*err = errno;
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else
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*err = 0; /* short write */
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return FALSE;
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}
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*bytes_written += phdr->caplen;
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return TRUE;
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}
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gboolean
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libpcap_dump_flush(FILE *pd, int *err)
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{
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if (fflush(pd) == EOF) {
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if (err != NULL)
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*err = errno;
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return FALSE;
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}
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return TRUE;
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}
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gboolean
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libpcap_dump_close(FILE *pd, int *err)
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{
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if (fclose(pd) == EOF) {
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if (err != NULL)
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*err = errno;
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return FALSE;
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}
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return TRUE;
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}
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