1997-05-27 00:01:12 +00:00
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/*
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2001-04-03 04:18:09 +00:00
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* pcap-linux.c: Packet capture interface to the Linux kernel
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1997-05-27 00:01:12 +00:00
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*
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2001-04-03 04:18:09 +00:00
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* Copyright (c) 2000 Torsten Landschoff <torsten@debian.org>
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* Sebastian Krahmer <krahmer@cs.uni-potsdam.de>
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*
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* License: BSD
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. The names of the authors may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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1997-05-27 00:01:12 +00:00
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*/
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#ifndef lint
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static const char rcsid[] =
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2002-06-21 01:36:27 +00:00
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"@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.73 2001/12/10 07:14:16 guy Exp $ (LBL)";
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1997-05-27 00:01:12 +00:00
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#endif
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2001-04-03 04:18:09 +00:00
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/*
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* Known problems with 2.0[.x] kernels:
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*
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* - The loopback device gives every packet twice; on 2.2[.x] kernels,
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* if we use PF_PACKET, we can filter out the transmitted version
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* of the packet by using data in the "sockaddr_ll" returned by
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* "recvfrom()", but, on 2.0[.x] kernels, we have to use
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* PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
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* "sockaddr_pkt" which doesn't give us enough information to let
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* us do that.
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*
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* - We have to set the interface's IFF_PROMISC flag ourselves, if
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* we're to run in promiscuous mode, which means we have to turn
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* it off ourselves when we're done; the kernel doesn't keep track
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* of how many sockets are listening promiscuously, which means
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* it won't get turned off automatically when no sockets are
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* listening promiscuously. We catch "pcap_close()" and, for
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* interfaces we put into promiscuous mode, take them out of
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* promiscuous mode - which isn't necessarily the right thing to
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* do, if another socket also requested promiscuous mode between
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* the time when we opened the socket and the time when we close
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* the socket.
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2002-06-21 01:36:27 +00:00
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*
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* - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
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* return the amount of data that you could have read, rather than
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* the amount that was returned, so we can't just allocate a buffer
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* whose size is the snapshot length and pass the snapshot length
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* as the byte count, and also pass MSG_TRUNC, so that the return
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* value tells us how long the packet was on the wire.
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*
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* This means that, if we want to get the actual size of the packet,
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* so we can return it in the "len" field of the packet header,
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* we have to read the entire packet, not just the part that fits
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* within the snapshot length, and thus waste CPU time copying data
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* from the kernel that our caller won't see.
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*
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* We have to get the actual size, and supply it in "len", because
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* otherwise, the IP dissector in tcpdump, for example, will complain
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* about "truncated-ip", as the packet will appear to have been
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* shorter, on the wire, than the IP header said it should have been.
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2001-04-03 04:18:09 +00:00
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*/
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1997-05-27 00:01:12 +00:00
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2001-04-03 04:18:09 +00:00
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#ifdef HAVE_CONFIG_H
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#include "config.h"
|
1998-09-15 19:28:10 +00:00
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#endif
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1997-05-27 00:01:12 +00:00
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2001-04-03 04:18:09 +00:00
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#include "pcap-int.h"
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#include "sll.h"
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1997-05-27 00:01:12 +00:00
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#include <errno.h>
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#include <stdlib.h>
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#include <unistd.h>
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2001-04-03 04:18:09 +00:00
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#include <fcntl.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <sys/utsname.h>
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#include <net/if.h>
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#include <netinet/in.h>
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#include <linux/if_ether.h>
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#include <net/if_arp.h>
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1997-05-27 00:01:12 +00:00
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|
2002-06-21 01:36:27 +00:00
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/*
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* If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
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* sockets rather than SOCK_PACKET sockets.
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*
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* To use them, we include <linux/if_packet.h> rather than
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* <netpacket/packet.h>; we do so because
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*
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* some Linux distributions (e.g., Slackware 4.0) have 2.2 or
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* later kernels and libc5, and don't provide a <netpacket/packet.h>
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* file;
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*
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* not all versions of glibc2 have a <netpacket/packet.h> file
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* that defines stuff needed for some of the 2.4-or-later-kernel
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* features, so if the system has a 2.4 or later kernel, we
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* still can't use those features.
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*
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* We're already including a number of other <linux/XXX.h> headers, and
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* this code is Linux-specific (no other OS has PF_PACKET sockets as
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* a raw packet capture mechanism), so it's not as if you gain any
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* useful portability by using <netpacket/packet.h>
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*
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* XXX - should we just include <linux/if_packet.h> even if PF_PACKET
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* isn't defined? It only defines one data structure in 2.0.x, so
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* it shouldn't cause any problems.
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*/
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#ifdef PF_PACKET
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# include <linux/if_packet.h>
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1997-05-27 00:01:12 +00:00
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2001-04-03 04:18:09 +00:00
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/*
|
2002-06-21 01:36:27 +00:00
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* On at least some Linux distributions (for example, Red Hat 5.2),
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* there's no <netpacket/packet.h> file, but PF_PACKET is defined if
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* you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
|
2001-04-03 04:18:09 +00:00
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* any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
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* the PACKET_xxx stuff.
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*
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* So we check whether PACKET_HOST is defined, and assume that we have
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* PF_PACKET sockets only if it is defined.
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*/
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# ifdef PACKET_HOST
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# define HAVE_PF_PACKET_SOCKETS
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# endif /* PACKET_HOST */
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2002-06-21 01:36:27 +00:00
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#endif /* PF_PACKET */
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2001-04-03 04:18:09 +00:00
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#ifdef SO_ATTACH_FILTER
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#include <linux/types.h>
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#include <linux/filter.h>
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1997-05-27 00:01:12 +00:00
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#endif
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2001-04-03 04:18:09 +00:00
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#ifndef __GLIBC__
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typedef int socklen_t;
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#endif
|
1997-05-27 00:01:12 +00:00
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2001-04-03 04:18:09 +00:00
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#ifndef MSG_TRUNC
|
2002-06-21 01:36:27 +00:00
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/*
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* This is being compiled on a system that lacks MSG_TRUNC; define it
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* with the value it has in the 2.2 and later kernels, so that, on
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* those kernels, when we pass it in the flags argument to "recvfrom()"
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* we're passing the right value and thus get the MSG_TRUNC behavior
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* we want. (We don't get that behavior on 2.0[.x] kernels, because
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* they didn't support MSG_TRUNC.)
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*/
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#define MSG_TRUNC 0x20
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2001-04-03 04:18:09 +00:00
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#endif
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#define MAX_LINKHEADER_SIZE 256
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/*
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* When capturing on all interfaces we use this as the buffer size.
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* Should be bigger then all MTUs that occur in real life.
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* 64kB should be enough for now.
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*/
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#define BIGGER_THAN_ALL_MTUS (64*1024)
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/*
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* Prototypes for internal functions
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*/
|
2002-06-21 01:36:27 +00:00
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static void map_arphrd_to_dlt(pcap_t *, int);
|
2001-04-03 04:18:09 +00:00
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static int live_open_old(pcap_t *, char *, int, int, char *);
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static int live_open_new(pcap_t *, char *, int, int, char *);
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static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
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/*
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* Wrap some ioctl calls
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*/
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#ifdef HAVE_PF_PACKET_SOCKETS
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static int iface_get_id(int fd, const char *device, char *ebuf);
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#endif
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static int iface_get_mtu(int fd, const char *device, char *ebuf);
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static int iface_get_arptype(int fd, const char *device, char *ebuf);
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#ifdef HAVE_PF_PACKET_SOCKETS
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static int iface_bind(int fd, int ifindex, char *ebuf);
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#endif
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static int iface_bind_old(int fd, const char *device, char *ebuf);
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#ifdef SO_ATTACH_FILTER
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static int fix_program(pcap_t *handle, struct sock_fprog *fcode);
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static int fix_offset(struct bpf_insn *p);
|
2002-06-21 01:36:27 +00:00
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static int set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
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static int reset_kernel_filter(pcap_t *handle);
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static struct sock_filter total_insn
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= BPF_STMT(BPF_RET | BPF_K, 0);
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static struct sock_fprog total_fcode
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= { 1, &total_insn };
|
2001-04-03 04:18:09 +00:00
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#endif
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/*
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* Get a handle for a live capture from the given device. You can
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* pass NULL as device to get all packages (without link level
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* information of course). If you pass 1 as promisc the interface
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* will be set to promiscous mode (XXX: I think this usage should
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* be deprecated and functions be added to select that later allow
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* modification of that values -- Torsten).
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*
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* See also pcap(3).
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*/
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pcap_t *
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pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf)
|
1997-05-27 00:01:12 +00:00
|
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{
|
2002-06-21 01:36:27 +00:00
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pcap_t *handle;
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int mtu;
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struct utsname utsname;
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|
2001-04-03 04:18:09 +00:00
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/* Allocate a handle for this session. */
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|
2002-06-21 01:36:27 +00:00
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handle = malloc(sizeof(*handle));
|
2001-04-03 04:18:09 +00:00
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if (handle == NULL) {
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snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
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pcap_strerror(errno));
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return NULL;
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}
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|
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/* Initialize some components of the pcap structure. */
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memset(handle, 0, sizeof(*handle));
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handle->snapshot = snaplen;
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|
handle->md.timeout = to_ms;
|
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/*
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* NULL and "any" are special devices which give us the hint to
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* monitor all devices.
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|
*/
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if (!device || strcmp(device, "any") == 0) {
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device = NULL;
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|
|
handle->md.device = strdup("any");
|
2002-06-21 01:36:27 +00:00
|
|
|
if (promisc) {
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promisc = 0;
|
|
|
|
/* Just a warning. */
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
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|
"Promiscuous mode not supported on the \"any\" device");
|
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|
|
}
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|
2001-04-03 04:18:09 +00:00
|
|
|
} else
|
|
|
|
handle->md.device = strdup(device);
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|
|
|
|
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|
if (handle->md.device == NULL) {
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|
snprintf(ebuf, PCAP_ERRBUF_SIZE, "strdup: %s",
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|
|
|
pcap_strerror(errno) );
|
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|
|
free(handle);
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|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
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|
|
|
* Current Linux kernels use the protocol family PF_PACKET to
|
|
|
|
* allow direct access to all packets on the network while
|
|
|
|
* older kernels had a special socket type SOCK_PACKET to
|
|
|
|
* implement this feature.
|
|
|
|
* While this old implementation is kind of obsolete we need
|
|
|
|
* to be compatible with older kernels for a while so we are
|
|
|
|
* trying both methods with the newer method preferred.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (! (live_open_new(handle, device, promisc, to_ms, ebuf) ||
|
|
|
|
live_open_old(handle, device, promisc, to_ms, ebuf)) )
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* Both methods to open the packet socket failed. Tidy
|
|
|
|
* up and report our failure (ebuf is expected to be
|
|
|
|
* set by the functions above).
|
|
|
|
*/
|
1997-05-27 00:01:12 +00:00
|
|
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|
2001-04-03 04:18:09 +00:00
|
|
|
free(handle->md.device);
|
|
|
|
free(handle);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
/*
|
|
|
|
* Compute the buffer size.
|
|
|
|
*
|
|
|
|
* If we're using SOCK_PACKET, this might be a 2.0[.x] kernel,
|
|
|
|
* and might require special handling - check.
|
|
|
|
*/
|
|
|
|
if (handle->md.sock_packet && (uname(&utsname) < 0 ||
|
|
|
|
strncmp(utsname.release, "2.0", 3) == 0)) {
|
|
|
|
/*
|
|
|
|
* We're using a SOCK_PACKET structure, and either
|
|
|
|
* we couldn't find out what kernel release this is,
|
|
|
|
* or it's a 2.0[.x] kernel.
|
|
|
|
*
|
|
|
|
* In the 2.0[.x] kernel, a "recvfrom()" on
|
|
|
|
* a SOCK_PACKET socket, with MSG_TRUNC set, will
|
|
|
|
* return the number of bytes read, so if we pass
|
|
|
|
* a length based on the snapshot length, it'll
|
|
|
|
* return the number of bytes from the packet
|
|
|
|
* copied to userland, not the actual length
|
|
|
|
* of the packet.
|
|
|
|
*
|
|
|
|
* This means that, for example, the IP dissector
|
|
|
|
* in tcpdump will get handed a packet length less
|
|
|
|
* than the length in the IP header, and will
|
|
|
|
* complain about "truncated-ip".
|
|
|
|
*
|
|
|
|
* So we don't bother trying to copy from the
|
|
|
|
* kernel only the bytes in which we're interested,
|
|
|
|
* but instead copy them all, just as the older
|
|
|
|
* versions of libpcap for Linux did.
|
|
|
|
*
|
|
|
|
* The buffer therefore needs to be big enough to
|
|
|
|
* hold the largest packet we can get from this
|
|
|
|
* device. Unfortunately, we can't get the MRU
|
|
|
|
* of the network; we can only get the MTU. The
|
|
|
|
* MTU may be too small, in which case a packet larger
|
|
|
|
* than the buffer size will be truncated *and* we
|
|
|
|
* won't get the actual packet size.
|
|
|
|
*
|
|
|
|
* However, if the snapshot length is larger than
|
|
|
|
* the buffer size based on the MTU, we use the
|
|
|
|
* snapshot length as the buffer size, instead;
|
|
|
|
* this means that with a sufficiently large snapshot
|
|
|
|
* length we won't artificially truncate packets
|
|
|
|
* to the MTU-based size.
|
|
|
|
*
|
|
|
|
* This mess just one of many problems with packet
|
|
|
|
* capture on 2.0[.x] kernels; you really want a
|
|
|
|
* 2.2[.x] or later kernel if you want packet capture
|
|
|
|
* to work well.
|
|
|
|
*/
|
|
|
|
mtu = iface_get_mtu(handle->fd, device, ebuf);
|
|
|
|
if (mtu == -1) {
|
|
|
|
close(handle->fd);
|
|
|
|
free(handle->md.device);
|
|
|
|
free(handle);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
|
|
|
|
if (handle->bufsize < handle->snapshot)
|
|
|
|
handle->bufsize = handle->snapshot;
|
|
|
|
} else {
|
|
|
|
/*
|
|
|
|
* This is a 2.2[.x] or later kernel (we know that
|
|
|
|
* either because we're not using a SOCK_PACKET
|
|
|
|
* socket - PF_PACKET is supported only in 2.2
|
|
|
|
* and later kernels - or because we checked the
|
|
|
|
* kernel version).
|
|
|
|
*
|
|
|
|
* We can safely pass "recvfrom()" a byte count
|
|
|
|
* based on the snapshot length.
|
|
|
|
*/
|
|
|
|
handle->bufsize = handle->snapshot;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Allocate the buffer */
|
|
|
|
|
|
|
|
handle->buffer = malloc(handle->bufsize + handle->offset);
|
|
|
|
if (!handle->buffer) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"malloc: %s", pcap_strerror(errno));
|
|
|
|
close(handle->fd);
|
|
|
|
free(handle->md.device);
|
|
|
|
free(handle);
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
return handle;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* Read at most max_packets from the capture stream and call the callback
|
|
|
|
* for each of them. Returns the number of packets handled or -1 if an
|
|
|
|
* error occured.
|
|
|
|
*/
|
1997-05-27 00:01:12 +00:00
|
|
|
int
|
2001-04-03 04:18:09 +00:00
|
|
|
pcap_read(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
|
1997-05-27 00:01:12 +00:00
|
|
|
{
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* Currently, on Linux only one packet is delivered per read,
|
|
|
|
* so we don't loop.
|
|
|
|
*/
|
|
|
|
return pcap_read_packet(handle, callback, user);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Read a packet from the socket calling the handler provided by
|
|
|
|
* the user. Returns the number of packets received or -1 if an
|
|
|
|
* error occured.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
|
|
|
|
{
|
2002-06-21 01:36:27 +00:00
|
|
|
u_char *bp;
|
2001-04-03 04:18:09 +00:00
|
|
|
int offset;
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
|
|
struct sockaddr_ll from;
|
|
|
|
struct sll_header *hdrp;
|
|
|
|
#else
|
|
|
|
struct sockaddr from;
|
|
|
|
#endif
|
|
|
|
socklen_t fromlen;
|
|
|
|
int packet_len, caplen;
|
|
|
|
struct pcap_pkthdr pcap_header;
|
|
|
|
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
|
|
/*
|
|
|
|
* If this is a cooked device, leave extra room for a
|
|
|
|
* fake packet header.
|
|
|
|
*/
|
|
|
|
if (handle->md.cooked)
|
|
|
|
offset = SLL_HDR_LEN;
|
|
|
|
else
|
|
|
|
offset = 0;
|
|
|
|
#else
|
|
|
|
/*
|
|
|
|
* This system doesn't have PF_PACKET sockets, so it doesn't
|
|
|
|
* support cooked devices.
|
|
|
|
*/
|
|
|
|
offset = 0;
|
|
|
|
#endif
|
|
|
|
|
|
|
|
/* Receive a single packet from the kernel */
|
1997-05-27 00:01:12 +00:00
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
bp = handle->buffer + handle->offset;
|
1997-05-27 00:01:12 +00:00
|
|
|
do {
|
|
|
|
fromlen = sizeof(from);
|
2001-04-03 04:18:09 +00:00
|
|
|
packet_len = recvfrom(
|
2002-06-21 01:36:27 +00:00
|
|
|
handle->fd, bp + offset,
|
|
|
|
handle->bufsize - offset, MSG_TRUNC,
|
2001-04-03 04:18:09 +00:00
|
|
|
(struct sockaddr *) &from, &fromlen);
|
|
|
|
} while (packet_len == -1 && errno == EINTR);
|
1997-05-27 00:01:12 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/* Check if an error occured */
|
1997-05-27 00:01:12 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
if (packet_len == -1) {
|
|
|
|
if (errno == EAGAIN)
|
|
|
|
return 0; /* no packet there */
|
|
|
|
else {
|
|
|
|
snprintf(handle->errbuf, sizeof(handle->errbuf),
|
|
|
|
"recvfrom: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
2001-04-03 04:18:09 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
|
|
/*
|
|
|
|
* If this is from the loopback device, reject outgoing packets;
|
|
|
|
* we'll see the packet as an incoming packet as well, and
|
|
|
|
* we don't want to see it twice.
|
|
|
|
*
|
|
|
|
* We can only do this if we're using PF_PACKET; the address
|
|
|
|
* returned for SOCK_PACKET is a "sockaddr_pkt" which lacks
|
|
|
|
* the relevant packet type information.
|
|
|
|
*/
|
|
|
|
if (!handle->md.sock_packet &&
|
|
|
|
from.sll_ifindex == handle->md.lo_ifindex &&
|
|
|
|
from.sll_pkttype == PACKET_OUTGOING)
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
|
|
/*
|
|
|
|
* If this is a cooked device, fill in the fake packet header.
|
|
|
|
*/
|
|
|
|
if (handle->md.cooked) {
|
|
|
|
/*
|
|
|
|
* Add the length of the fake header to the length
|
|
|
|
* of packet data we read.
|
|
|
|
*/
|
|
|
|
packet_len += SLL_HDR_LEN;
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
hdrp = (struct sll_header *)bp;
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Map the PACKET_ value to a LINUX_SLL_ value; we
|
|
|
|
* want the same numerical value to be used in
|
|
|
|
* the link-layer header even if the numerical values
|
|
|
|
* for the PACKET_ #defines change, so that programs
|
|
|
|
* that look at the packet type field will always be
|
|
|
|
* able to handle DLT_LINUX_SLL captures.
|
|
|
|
*/
|
|
|
|
switch (from.sll_pkttype) {
|
|
|
|
|
|
|
|
case PACKET_HOST:
|
|
|
|
hdrp->sll_pkttype = htons(LINUX_SLL_HOST);
|
|
|
|
break;
|
|
|
|
|
|
|
|
case PACKET_BROADCAST:
|
|
|
|
hdrp->sll_pkttype = htons(LINUX_SLL_BROADCAST);
|
|
|
|
break;
|
|
|
|
|
|
|
|
case PACKET_MULTICAST:
|
|
|
|
hdrp->sll_pkttype = htons(LINUX_SLL_MULTICAST);
|
|
|
|
break;
|
|
|
|
|
|
|
|
case PACKET_OTHERHOST:
|
|
|
|
hdrp->sll_pkttype = htons(LINUX_SLL_OTHERHOST);
|
|
|
|
break;
|
|
|
|
|
|
|
|
case PACKET_OUTGOING:
|
|
|
|
hdrp->sll_pkttype = htons(LINUX_SLL_OUTGOING);
|
|
|
|
break;
|
|
|
|
|
|
|
|
default:
|
|
|
|
hdrp->sll_pkttype = -1;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
hdrp->sll_hatype = htons(from.sll_hatype);
|
|
|
|
hdrp->sll_halen = htons(from.sll_halen);
|
|
|
|
memcpy(hdrp->sll_addr, from.sll_addr,
|
|
|
|
(from.sll_halen > SLL_ADDRLEN) ?
|
|
|
|
SLL_ADDRLEN :
|
|
|
|
from.sll_halen);
|
|
|
|
hdrp->sll_protocol = from.sll_protocol;
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
|
|
|
|
/*
|
|
|
|
* XXX: According to the kernel source we should get the real
|
|
|
|
* packet len if calling recvfrom with MSG_TRUNC set. It does
|
|
|
|
* not seem to work here :(, but it is supported by this code
|
|
|
|
* anyway.
|
|
|
|
* To be honest the code RELIES on that feature so this is really
|
|
|
|
* broken with 2.2.x kernels.
|
|
|
|
* I spend a day to figure out what's going on and I found out
|
|
|
|
* that the following is happening:
|
|
|
|
*
|
|
|
|
* The packet comes from a random interface and the packet_rcv
|
|
|
|
* hook is called with a clone of the packet. That code inserts
|
|
|
|
* the packet into the receive queue of the packet socket.
|
|
|
|
* If a filter is attached to that socket that filter is run
|
|
|
|
* first - and there lies the problem. The default filter always
|
|
|
|
* cuts the packet at the snaplen:
|
|
|
|
*
|
|
|
|
* # tcpdump -d
|
|
|
|
* (000) ret #68
|
|
|
|
*
|
|
|
|
* So the packet filter cuts down the packet. The recvfrom call
|
|
|
|
* says "hey, it's only 68 bytes, it fits into the buffer" with
|
|
|
|
* the result that we don't get the real packet length. This
|
|
|
|
* is valid at least until kernel 2.2.17pre6.
|
|
|
|
*
|
|
|
|
* We currently handle this by making a copy of the filter
|
|
|
|
* program, fixing all "ret" instructions with non-zero
|
|
|
|
* operands to have an operand of 65535 so that the filter
|
|
|
|
* doesn't truncate the packet, and supplying that modified
|
|
|
|
* filter to the kernel.
|
|
|
|
*/
|
|
|
|
|
|
|
|
caplen = packet_len;
|
|
|
|
if (caplen > handle->snapshot)
|
|
|
|
caplen = handle->snapshot;
|
|
|
|
|
|
|
|
/* Run the packet filter if not using kernel filter */
|
|
|
|
if (!handle->md.use_bpf && handle->fcode.bf_insns) {
|
2002-06-21 01:36:27 +00:00
|
|
|
if (bpf_filter(handle->fcode.bf_insns, bp,
|
2001-04-03 04:18:09 +00:00
|
|
|
packet_len, caplen) == 0)
|
|
|
|
{
|
|
|
|
/* rejected by filter */
|
|
|
|
return 0;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
}
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
/* Fill in our own header data */
|
|
|
|
|
|
|
|
if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) {
|
|
|
|
snprintf(handle->errbuf, sizeof(handle->errbuf),
|
|
|
|
"ioctl: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
pcap_header.caplen = caplen;
|
|
|
|
pcap_header.len = packet_len;
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
/*
|
|
|
|
* Count the packet.
|
|
|
|
*
|
|
|
|
* Arguably, we should count them before we check the filter,
|
|
|
|
* as on many other platforms "ps_recv" counts packets
|
|
|
|
* handed to the filter rather than packets that passed
|
|
|
|
* the filter, but if filtering is done in the kernel, we
|
|
|
|
* can't get a count of packets that passed the filter,
|
|
|
|
* and that would mean the meaning of "ps_recv" wouldn't
|
|
|
|
* be the same on all Linux systems.
|
|
|
|
*
|
|
|
|
* XXX - it's not the same on all systems in any case;
|
|
|
|
* ideally, we should have a "get the statistics" call
|
|
|
|
* that supplies more counts and indicates which of them
|
|
|
|
* it supplies, so that we supply a count of packets
|
|
|
|
* handed to the filter only on platforms where that
|
|
|
|
* information is available.
|
|
|
|
*
|
|
|
|
* We count them here even if we can get the packet count
|
|
|
|
* from the kernel, as we can only determine at run time
|
|
|
|
* whether we'll be able to get it from the kernel (if
|
|
|
|
* HAVE_TPACKET_STATS isn't defined, we can't get it from
|
|
|
|
* the kernel, but if it is defined, the library might
|
|
|
|
* have been built with a 2.4 or later kernel, but we
|
|
|
|
* might be running on a 2.2[.x] kernel without Alexey
|
|
|
|
* Kuznetzov's turbopacket patches, and thus the kernel
|
|
|
|
* might not be able to supply those statistics). We
|
|
|
|
* could, I guess, try, when opening the socket, to get
|
|
|
|
* the statistics, and if we can not increment the count
|
|
|
|
* here, but it's not clear that always incrementing
|
|
|
|
* the count is more expensive than always testing a flag
|
|
|
|
* in memory.
|
|
|
|
*/
|
2001-04-03 04:18:09 +00:00
|
|
|
handle->md.stat.ps_recv++;
|
2002-06-21 01:36:27 +00:00
|
|
|
|
|
|
|
/* Call the user supplied callback function */
|
|
|
|
callback(userdata, &pcap_header, bp);
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
return 1;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* Get the statistics for the given packet capture handle.
|
2002-06-21 01:36:27 +00:00
|
|
|
* Reports the number of dropped packets iff the kernel supports
|
|
|
|
* the PACKET_STATISTICS "getsockopt()" argument (2.4 and later
|
|
|
|
* kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket
|
|
|
|
* patches); otherwise, that information isn't available, and we lie
|
|
|
|
* and report 0 as the count of dropped packets.
|
2001-04-03 04:18:09 +00:00
|
|
|
*/
|
|
|
|
int
|
|
|
|
pcap_stats(pcap_t *handle, struct pcap_stat *stats)
|
1997-05-27 00:01:12 +00:00
|
|
|
{
|
2002-06-21 01:36:27 +00:00
|
|
|
#ifdef HAVE_TPACKET_STATS
|
|
|
|
struct tpacket_stats kstats;
|
|
|
|
socklen_t len = sizeof (struct tpacket_stats);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Try to get the packet counts from the kernel.
|
|
|
|
*/
|
|
|
|
if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
|
|
|
|
&kstats, &len) > -1) {
|
|
|
|
/*
|
|
|
|
* In "linux/net/packet/af_packet.c", at least in the
|
|
|
|
* 2.4.9 kernel, "tp_packets" is incremented for every
|
|
|
|
* packet that passes the packet filter *and* is
|
|
|
|
* successfully queued on the socket; "tp_drops" is
|
|
|
|
* incremented for every packet dropped because there's
|
|
|
|
* not enough free space in the socket buffer.
|
|
|
|
*
|
|
|
|
* When the statistics are returned for a PACKET_STATISTICS
|
|
|
|
* "getsockopt()" call, "tp_drops" is added to "tp_packets",
|
|
|
|
* so that "tp_packets" counts all packets handed to
|
|
|
|
* the PF_PACKET socket, including packets dropped because
|
|
|
|
* there wasn't room on the socket buffer - but not
|
|
|
|
* including packets that didn't pass the filter.
|
|
|
|
*
|
|
|
|
* In the BSD BPF, the count of received packets is
|
|
|
|
* incremented for every packet handed to BPF, regardless
|
|
|
|
* of whether it passed the filter.
|
|
|
|
*
|
|
|
|
* We can't make "pcap_stats()" work the same on both
|
|
|
|
* platforms, but the best approximation is to return
|
|
|
|
* "tp_packets" as the count of packets and "tp_drops"
|
|
|
|
* as the count of drops.
|
|
|
|
*/
|
|
|
|
handle->md.stat.ps_recv = kstats.tp_packets;
|
|
|
|
handle->md.stat.ps_drop = kstats.tp_drops;
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* If the error was EOPNOTSUPP, fall through, so that
|
|
|
|
* if you build the library on a system with
|
|
|
|
* "struct tpacket_stats" and run it on a system
|
|
|
|
* that doesn't, it works as it does if the library
|
|
|
|
* is built on a system without "struct tpacket_stats".
|
|
|
|
*/
|
|
|
|
if (errno != EOPNOTSUPP) {
|
|
|
|
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"pcap_stats: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
/*
|
|
|
|
* On systems where the PACKET_STATISTICS "getsockopt()" argument
|
|
|
|
* is supported on PF_PACKET sockets:
|
|
|
|
*
|
|
|
|
* "ps_recv" counts only packets that *passed* the filter,
|
|
|
|
* not packets that didn't pass the filter. This includes
|
|
|
|
* packets later dropped because we ran out of buffer space.
|
|
|
|
*
|
|
|
|
* "ps_drop" counts packets dropped because we ran out of
|
|
|
|
* buffer space. It doesn't count packets dropped by the
|
|
|
|
* interface driver. It counts only packets that passed
|
|
|
|
* the filter.
|
|
|
|
*
|
|
|
|
* Both statistics include packets not yet read from the
|
|
|
|
* kernel by libpcap, and thus not yet seen by the application.
|
|
|
|
*
|
|
|
|
* On systems where the PACKET_STATISTICS "getsockopt()" argument
|
|
|
|
* is not supported on PF_PACKET sockets:
|
|
|
|
*
|
|
|
|
* "ps_recv" counts only packets that *passed* the filter,
|
|
|
|
* not packets that didn't pass the filter. It does not
|
|
|
|
* count packets dropped because we ran out of buffer
|
|
|
|
* space.
|
|
|
|
*
|
|
|
|
* "ps_drop" is not supported.
|
|
|
|
*
|
|
|
|
* "ps_recv" doesn't include packets not yet read from
|
|
|
|
* the kernel by libpcap.
|
|
|
|
*/
|
2001-04-03 04:18:09 +00:00
|
|
|
*stats = handle->md.stat;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Attach the given BPF code to the packet capture device.
|
|
|
|
*/
|
|
|
|
int
|
|
|
|
pcap_setfilter(pcap_t *handle, struct bpf_program *filter)
|
|
|
|
{
|
|
|
|
#ifdef SO_ATTACH_FILTER
|
|
|
|
struct sock_fprog fcode;
|
|
|
|
int can_filter_in_kernel;
|
|
|
|
#endif
|
|
|
|
|
|
|
|
if (!handle)
|
|
|
|
return -1;
|
|
|
|
if (!filter) {
|
|
|
|
strncpy(handle->errbuf, "setfilter: No filter specified",
|
|
|
|
sizeof(handle->errbuf));
|
|
|
|
return -1;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/* Make our private copy of the filter */
|
|
|
|
|
|
|
|
if (install_bpf_program(handle, filter) < 0) {
|
|
|
|
snprintf(handle->errbuf, sizeof(handle->errbuf),
|
|
|
|
"malloc: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
1998-09-15 19:28:10 +00:00
|
|
|
}
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Run user level packet filter by default. Will be overriden if
|
|
|
|
* installing a kernel filter succeeds.
|
|
|
|
*/
|
|
|
|
handle->md.use_bpf = 0;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* If we're reading from a savefile, don't try to install
|
|
|
|
* a kernel filter.
|
|
|
|
*/
|
|
|
|
if (handle->sf.rfile != NULL)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
/* Install kernel level filter if possible */
|
|
|
|
|
|
|
|
#ifdef SO_ATTACH_FILTER
|
|
|
|
#ifdef USHRT_MAX
|
|
|
|
if (handle->fcode.bf_len > USHRT_MAX) {
|
|
|
|
/*
|
|
|
|
* fcode.len is an unsigned short for current kernel.
|
|
|
|
* I have yet to see BPF-Code with that much
|
|
|
|
* instructions but still it is possible. So for the
|
|
|
|
* sake of correctness I added this check.
|
|
|
|
*/
|
|
|
|
fprintf(stderr, "Warning: Filter too complex for kernel\n");
|
|
|
|
fcode.filter = NULL;
|
|
|
|
can_filter_in_kernel = 0;
|
|
|
|
} else
|
|
|
|
#endif /* USHRT_MAX */
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* Oh joy, the Linux kernel uses struct sock_fprog instead
|
|
|
|
* of struct bpf_program and of course the length field is
|
|
|
|
* of different size. Pointed out by Sebastian
|
|
|
|
*
|
|
|
|
* Oh, and we also need to fix it up so that all "ret"
|
|
|
|
* instructions with non-zero operands have 65535 as the
|
|
|
|
* operand, and so that, if we're in cooked mode, all
|
|
|
|
* memory-reference instructions use special magic offsets
|
|
|
|
* in references to the link-layer header and assume that
|
|
|
|
* the link-layer payload begins at 0; "fix_program()"
|
|
|
|
* will do that.
|
|
|
|
*/
|
|
|
|
switch (fix_program(handle, &fcode)) {
|
|
|
|
|
|
|
|
case -1:
|
|
|
|
default:
|
|
|
|
/*
|
|
|
|
* Fatal error; just quit.
|
|
|
|
* (The "default" case shouldn't happen; we
|
|
|
|
* return -1 for that reason.)
|
|
|
|
*/
|
|
|
|
return -1;
|
|
|
|
|
|
|
|
case 0:
|
|
|
|
/*
|
|
|
|
* The program performed checks that we can't make
|
|
|
|
* work in the kernel.
|
|
|
|
*/
|
|
|
|
can_filter_in_kernel = 0;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case 1:
|
|
|
|
/*
|
|
|
|
* We have a filter that'll work in the kernel.
|
|
|
|
*/
|
|
|
|
can_filter_in_kernel = 1;
|
|
|
|
break;
|
|
|
|
}
|
1998-09-15 19:28:10 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
if (can_filter_in_kernel) {
|
2002-06-21 01:36:27 +00:00
|
|
|
if (set_kernel_filter(handle, &fcode) == 0)
|
2001-04-03 04:18:09 +00:00
|
|
|
{
|
|
|
|
/* Installation succeded - using kernel filter. */
|
|
|
|
handle->md.use_bpf = 1;
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* Print a warning if we weren't able to install
|
|
|
|
* the filter for a reason other than "this kernel
|
|
|
|
* isn't configured to support socket filters.
|
|
|
|
*/
|
|
|
|
if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
|
|
|
|
fprintf(stderr,
|
|
|
|
"Warning: Kernel filter failed: %s\n",
|
|
|
|
pcap_strerror(errno));
|
|
|
|
}
|
|
|
|
}
|
1998-09-15 19:28:10 +00:00
|
|
|
}
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
/*
|
|
|
|
* If we're not using the kernel filter, get rid of any kernel
|
|
|
|
* filter that might've been there before, e.g. because the
|
|
|
|
* previous filter could work in the kernel, or because some other
|
|
|
|
* code attached a filter to the socket by some means other than
|
|
|
|
* calling "pcap_setfilter()". Otherwise, the kernel filter may
|
|
|
|
* filter out packets that would pass the new userland filter.
|
|
|
|
*/
|
|
|
|
if (!handle->md.use_bpf)
|
|
|
|
reset_kernel_filter(handle);
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* Free up the copy of the filter that was made by "fix_program()".
|
|
|
|
*/
|
|
|
|
if (fcode.filter != NULL)
|
|
|
|
free(fcode.filter);
|
|
|
|
#endif /* SO_ATTACH_FILTER */
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Linux uses the ARP hardware type to identify the type of an
|
|
|
|
* interface. pcap uses the DLT_xxx constants for this. This
|
2002-06-21 01:36:27 +00:00
|
|
|
* function takes a pointer to a "pcap_t", and an ARPHRD_xxx
|
|
|
|
* constant, as arguments, and sets "handle->linktype" to the
|
|
|
|
* appropriate DLT_XXX constant and sets "handle->offset" to
|
|
|
|
* the appropriate value (to make "handle->offset" plus link-layer
|
|
|
|
* header length be a multiple of 4, so that the link-layer payload
|
|
|
|
* will be aligned on a 4-byte boundary when capturing packets).
|
|
|
|
* (If the offset isn't set here, it'll be 0; add code as appropriate
|
|
|
|
* for cases where it shouldn't be 0.)
|
2001-04-03 04:18:09 +00:00
|
|
|
*
|
2002-06-21 01:36:27 +00:00
|
|
|
* Sets the link type to -1 if unable to map the type.
|
2001-04-03 04:18:09 +00:00
|
|
|
*/
|
2002-06-21 01:36:27 +00:00
|
|
|
static void map_arphrd_to_dlt(pcap_t *handle, int arptype)
|
2001-04-03 04:18:09 +00:00
|
|
|
{
|
|
|
|
switch (arptype) {
|
2002-06-21 01:36:27 +00:00
|
|
|
|
1998-09-15 19:28:10 +00:00
|
|
|
case ARPHRD_ETHER:
|
|
|
|
case ARPHRD_METRICOM:
|
2002-06-21 01:36:27 +00:00
|
|
|
case ARPHRD_LOOPBACK:
|
|
|
|
handle->linktype = DLT_EN10MB;
|
|
|
|
handle->offset = 2;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case ARPHRD_EETHER:
|
|
|
|
handle->linktype = DLT_EN3MB;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case ARPHRD_AX25:
|
|
|
|
handle->linktype = DLT_AX25;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case ARPHRD_PRONET:
|
|
|
|
handle->linktype = DLT_PRONET;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case ARPHRD_CHAOS:
|
|
|
|
handle->linktype = DLT_CHAOS;
|
|
|
|
break;
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
#ifndef ARPHRD_IEEE802_TR
|
|
|
|
#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */
|
|
|
|
#endif
|
|
|
|
case ARPHRD_IEEE802_TR:
|
2002-06-21 01:36:27 +00:00
|
|
|
case ARPHRD_IEEE802:
|
|
|
|
handle->linktype = DLT_IEEE802;
|
|
|
|
handle->offset = 2;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case ARPHRD_ARCNET:
|
|
|
|
handle->linktype = DLT_ARCNET;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case ARPHRD_FDDI:
|
|
|
|
handle->linktype = DLT_FDDI;
|
|
|
|
handle->offset = 3;
|
|
|
|
break;
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
#ifndef ARPHRD_ATM /* FIXME: How to #include this? */
|
|
|
|
#define ARPHRD_ATM 19
|
|
|
|
#endif
|
2002-06-21 01:36:27 +00:00
|
|
|
case ARPHRD_ATM:
|
|
|
|
/*
|
|
|
|
* The Classical IP implementation in ATM for Linux
|
|
|
|
* supports both what RFC 1483 calls "LLC Encapsulation",
|
|
|
|
* in which each packet has an LLC header, possibly
|
|
|
|
* with a SNAP header as well, prepended to it, and
|
|
|
|
* what RFC 1483 calls "VC Based Multiplexing", in which
|
|
|
|
* different virtual circuits carry different network
|
|
|
|
* layer protocols, and no header is prepended to packets.
|
|
|
|
*
|
|
|
|
* They both have an ARPHRD_ type of ARPHRD_ATM, so
|
|
|
|
* you can't use the ARPHRD_ type to find out whether
|
|
|
|
* captured packets will have an LLC header, and,
|
|
|
|
* while there's a socket ioctl to *set* the encapsulation
|
|
|
|
* type, there's no ioctl to *get* the encapsulation type.
|
|
|
|
*
|
|
|
|
* This means that
|
|
|
|
*
|
|
|
|
* programs that dissect Linux Classical IP frames
|
|
|
|
* would have to check for an LLC header and,
|
|
|
|
* depending on whether they see one or not, dissect
|
|
|
|
* the frame as LLC-encapsulated or as raw IP (I
|
|
|
|
* don't know whether there's any traffic other than
|
|
|
|
* IP that would show up on the socket, or whether
|
|
|
|
* there's any support for IPv6 in the Linux
|
|
|
|
* Classical IP code);
|
|
|
|
*
|
|
|
|
* filter expressions would have to compile into
|
|
|
|
* code that checks for an LLC header and does
|
|
|
|
* the right thing.
|
|
|
|
*
|
|
|
|
* Both of those are a nuisance - and, at least on systems
|
|
|
|
* that support PF_PACKET sockets, we don't have to put
|
|
|
|
* up with those nuisances; instead, we can just capture
|
|
|
|
* in cooked mode. That's what we'll do.
|
|
|
|
*/
|
|
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
|
|
break;
|
|
|
|
|
|
|
|
#ifndef ARPHRD_IEEE80211 /* From Linux 2.4.6 */
|
|
|
|
#define ARPHRD_IEEE80211 801
|
|
|
|
#endif
|
|
|
|
case ARPHRD_IEEE80211:
|
|
|
|
handle->linktype = DLT_IEEE802_11;
|
|
|
|
break;
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
case ARPHRD_PPP:
|
2002-06-21 01:36:27 +00:00
|
|
|
/*
|
|
|
|
* Some PPP code in the kernel supplies no link-layer
|
|
|
|
* header whatsoever to PF_PACKET sockets; other PPP
|
|
|
|
* code supplies PPP link-layer headers ("syncppp.c");
|
|
|
|
* some PPP code might supply random link-layer
|
|
|
|
* headers (PPP over ISDN - there's code in Ethereal,
|
|
|
|
* for example, to cope with PPP-over-ISDN captures
|
|
|
|
* with which the Ethereal developers have had to cope,
|
|
|
|
* heuristically trying to determine which of the
|
|
|
|
* oddball link-layer headers particular packets have).
|
|
|
|
*
|
|
|
|
* As such, we just punt, and run all PPP interfaces
|
|
|
|
* in cooked mode.
|
|
|
|
*/
|
|
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
|
|
break;
|
|
|
|
|
|
|
|
case ARPHRD_HDLC:
|
|
|
|
handle->linktype = DLT_C_HDLC;
|
|
|
|
break;
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/* Not sure if this is correct for all tunnels, but it
|
|
|
|
* works for CIPE */
|
|
|
|
case ARPHRD_TUNNEL:
|
|
|
|
#ifndef ARPHRD_SIT
|
|
|
|
#define ARPHRD_SIT 776 /* From Linux 2.2.14 */
|
|
|
|
#endif
|
|
|
|
case ARPHRD_SIT:
|
1998-09-15 19:28:10 +00:00
|
|
|
case ARPHRD_CSLIP:
|
|
|
|
case ARPHRD_SLIP6:
|
|
|
|
case ARPHRD_CSLIP6:
|
2002-06-21 01:36:27 +00:00
|
|
|
case ARPHRD_ADAPT:
|
|
|
|
case ARPHRD_SLIP:
|
|
|
|
/*
|
|
|
|
* XXX - should some of those be mapped to DLT_LINUX_SLL
|
|
|
|
* instead? Should we just map all of them to DLT_LINUX_SLL?
|
|
|
|
*/
|
|
|
|
handle->linktype = DLT_RAW;
|
|
|
|
break;
|
2001-04-03 04:18:09 +00:00
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
case ARPHRD_LOCALTLK:
|
|
|
|
handle->linktype = DLT_LTALK;
|
|
|
|
break;
|
|
|
|
|
|
|
|
default:
|
|
|
|
handle->linktype = -1;
|
|
|
|
break;
|
|
|
|
}
|
2001-04-03 04:18:09 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
/* ===== Functions to interface to the newer kernels ================== */
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Try to open a packet socket using the new kernel interface.
|
|
|
|
* Returns 0 on failure.
|
|
|
|
* FIXME: 0 uses to mean success (Sebastian)
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
live_open_new(pcap_t *handle, char *device, int promisc,
|
|
|
|
int to_ms, char *ebuf)
|
|
|
|
{
|
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
2002-06-21 01:36:27 +00:00
|
|
|
int sock_fd = -1, device_id, arptype;
|
2001-04-03 04:18:09 +00:00
|
|
|
struct packet_mreq mr;
|
|
|
|
|
|
|
|
/* One shot loop used for error handling - bail out with break */
|
|
|
|
|
|
|
|
do {
|
|
|
|
/*
|
|
|
|
* Open a socket with protocol family packet. If a device is
|
|
|
|
* given we try to open it in raw mode otherwise we use
|
|
|
|
* the cooked interface.
|
|
|
|
*/
|
|
|
|
sock_fd = device ?
|
|
|
|
socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
|
|
|
|
: socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
|
|
|
|
|
|
|
|
if (sock_fd == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE, "socket: %s",
|
|
|
|
pcap_strerror(errno) );
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* It seems the kernel supports the new interface. */
|
|
|
|
handle->md.sock_packet = 0;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Get the interface index of the loopback device.
|
|
|
|
* If the attempt fails, don't fail, just set the
|
|
|
|
* "md.lo_ifindex" to -1.
|
|
|
|
*
|
|
|
|
* XXX - can there be more than one device that loops
|
|
|
|
* packets back, i.e. devices other than "lo"? If so,
|
|
|
|
* we'd need to find them all, and have an array of
|
|
|
|
* indices for them, and check all of them in
|
|
|
|
* "pcap_read_packet()".
|
|
|
|
*/
|
|
|
|
handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", ebuf);
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
/*
|
|
|
|
* Default value for offset to align link-layer payload
|
|
|
|
* on a 4-byte boundary.
|
|
|
|
*/
|
|
|
|
handle->offset = 0;
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* What kind of frames do we have to deal with? Fall back
|
|
|
|
* to cooked mode if we have an unknown interface type.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (device) {
|
|
|
|
/* Assume for now we don't need cooked mode. */
|
|
|
|
handle->md.cooked = 0;
|
|
|
|
|
|
|
|
arptype = iface_get_arptype(sock_fd, device, ebuf);
|
|
|
|
if (arptype == -1)
|
|
|
|
break;
|
2002-06-21 01:36:27 +00:00
|
|
|
map_arphrd_to_dlt(handle, arptype);
|
2001-04-03 04:18:09 +00:00
|
|
|
if (handle->linktype == -1 ||
|
2002-06-21 01:36:27 +00:00
|
|
|
handle->linktype == DLT_LINUX_SLL ||
|
2001-04-03 04:18:09 +00:00
|
|
|
(handle->linktype == DLT_EN10MB &&
|
|
|
|
(strncmp("isdn", device, 4) == 0 ||
|
2002-06-21 01:36:27 +00:00
|
|
|
strncmp("isdY", device, 4) == 0))) {
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
2002-06-21 01:36:27 +00:00
|
|
|
* Unknown interface type (-1), or a
|
|
|
|
* device we explicitly chose to run
|
|
|
|
* in cooked mode (e.g., PPP devices),
|
|
|
|
* or an ISDN device (whose link-layer
|
|
|
|
* type we can only determine by using
|
|
|
|
* APIs that may be different on different
|
2001-04-03 04:18:09 +00:00
|
|
|
* kernels) - reopen in cooked mode.
|
|
|
|
*/
|
|
|
|
if (close(sock_fd) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"close: %s", pcap_strerror(errno));
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
sock_fd = socket(PF_PACKET, SOCK_DGRAM,
|
|
|
|
htons(ETH_P_ALL));
|
|
|
|
if (sock_fd == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"socket: %s", pcap_strerror(errno));
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
handle->md.cooked = 1;
|
|
|
|
|
|
|
|
if (handle->linktype == -1) {
|
|
|
|
/*
|
|
|
|
* Warn that we're falling back on
|
|
|
|
* cooked mode; we may want to
|
|
|
|
* update "map_arphrd_to_dlt()"
|
|
|
|
* to handle the new type.
|
|
|
|
*/
|
2002-06-21 01:36:27 +00:00
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"arptype %d not "
|
2001-04-03 04:18:09 +00:00
|
|
|
"supported by libpcap - "
|
|
|
|
"falling back to cooked "
|
2002-06-21 01:36:27 +00:00
|
|
|
"socket",
|
2001-04-03 04:18:09 +00:00
|
|
|
arptype);
|
|
|
|
}
|
|
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
|
|
}
|
|
|
|
|
|
|
|
device_id = iface_get_id(sock_fd, device, ebuf);
|
|
|
|
if (device_id == -1)
|
|
|
|
break;
|
|
|
|
|
|
|
|
if (iface_bind(sock_fd, device_id, ebuf) == -1)
|
|
|
|
break;
|
|
|
|
} else {
|
|
|
|
/*
|
|
|
|
* This is cooked mode.
|
|
|
|
*/
|
|
|
|
handle->md.cooked = 1;
|
|
|
|
handle->linktype = DLT_LINUX_SLL;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* XXX - squelch GCC complaints about
|
|
|
|
* uninitialized variables; if we can't
|
|
|
|
* select promiscuous mode on all interfaces,
|
|
|
|
* we should move the code below into the
|
|
|
|
* "if (device)" branch of the "if" and
|
|
|
|
* get rid of the next statement.
|
|
|
|
*/
|
|
|
|
device_id = -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Select promiscuous mode on/off */
|
|
|
|
|
|
|
|
#ifdef SOL_PACKET
|
|
|
|
/*
|
|
|
|
* Hmm, how can we set promiscuous mode on all interfaces?
|
|
|
|
* I am not sure if that is possible at all.
|
|
|
|
*/
|
|
|
|
|
|
|
|
if (device) {
|
|
|
|
memset(&mr, 0, sizeof(mr));
|
|
|
|
mr.mr_ifindex = device_id;
|
|
|
|
mr.mr_type = promisc ?
|
|
|
|
PACKET_MR_PROMISC : PACKET_MR_ALLMULTI;
|
|
|
|
if (setsockopt(sock_fd, SOL_PACKET,
|
|
|
|
PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1)
|
|
|
|
{
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"setsockopt: %s", pcap_strerror(errno));
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
1998-09-15 19:28:10 +00:00
|
|
|
#endif
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
/* Save the socket FD in the pcap structure */
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
handle->fd = sock_fd;
|
|
|
|
|
|
|
|
return 1;
|
|
|
|
|
|
|
|
} while(0);
|
|
|
|
|
|
|
|
if (sock_fd != -1)
|
|
|
|
close(sock_fd);
|
|
|
|
return 0;
|
|
|
|
#else
|
|
|
|
strncpy(ebuf,
|
|
|
|
"New packet capturing interface not supported by build "
|
|
|
|
"environment", PCAP_ERRBUF_SIZE);
|
|
|
|
return 0;
|
1998-09-15 19:28:10 +00:00
|
|
|
#endif
|
2001-04-03 04:18:09 +00:00
|
|
|
}
|
1998-09-15 19:28:10 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
#ifdef HAVE_PF_PACKET_SOCKETS
|
|
|
|
/*
|
|
|
|
* Return the index of the given device name. Fill ebuf and return
|
|
|
|
* -1 on failure.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
iface_get_id(int fd, const char *device, char *ebuf)
|
|
|
|
{
|
|
|
|
struct ifreq ifr;
|
1997-05-27 00:01:12 +00:00
|
|
|
|
1998-09-15 19:28:10 +00:00
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"ioctl: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
return ifr.ifr_ifindex;
|
|
|
|
}
|
1997-05-27 00:01:12 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* Bind the socket associated with FD to the given device.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
iface_bind(int fd, int ifindex, char *ebuf)
|
|
|
|
{
|
|
|
|
struct sockaddr_ll sll;
|
|
|
|
|
|
|
|
memset(&sll, 0, sizeof(sll));
|
|
|
|
sll.sll_family = AF_PACKET;
|
|
|
|
sll.sll_ifindex = ifindex;
|
|
|
|
sll.sll_protocol = htons(ETH_P_ALL);
|
|
|
|
|
|
|
|
if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"bind: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
|
|
/* ===== Functions to interface to the older kernels ================== */
|
|
|
|
|
|
|
|
/*
|
|
|
|
* With older kernels promiscuous mode is kind of interesting because we
|
|
|
|
* have to reset the interface before exiting. The problem can't really
|
|
|
|
* be solved without some daemon taking care of managing usage counts.
|
|
|
|
* If we put the interface into promiscuous mode, we set a flag indicating
|
|
|
|
* that we must take it out of that mode when the interface is closed,
|
|
|
|
* and, when closing the interface, if that flag is set we take it out
|
|
|
|
* of promiscuous mode.
|
|
|
|
*/
|
|
|
|
|
|
|
|
/*
|
|
|
|
* List of pcaps for which we turned promiscuous mode on by hand.
|
|
|
|
* If there are any such pcaps, we arrange to call "pcap_close_all()"
|
|
|
|
* when we exit, and have it close all of them to turn promiscuous mode
|
|
|
|
* off.
|
|
|
|
*/
|
|
|
|
static struct pcap *pcaps_to_close;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* TRUE if we've already called "atexit()" to cause "pcap_close_all()" to
|
|
|
|
* be called on exit.
|
|
|
|
*/
|
|
|
|
static int did_atexit;
|
|
|
|
|
|
|
|
static void pcap_close_all(void)
|
|
|
|
{
|
|
|
|
struct pcap *handle;
|
|
|
|
|
|
|
|
while ((handle = pcaps_to_close) != NULL)
|
|
|
|
pcap_close(handle);
|
|
|
|
}
|
|
|
|
|
|
|
|
void pcap_close_linux( pcap_t *handle )
|
|
|
|
{
|
|
|
|
struct pcap *p, *prevp;
|
|
|
|
struct ifreq ifr;
|
|
|
|
|
|
|
|
if (handle->md.clear_promisc) {
|
|
|
|
/*
|
|
|
|
* We put the interface into promiscuous mode; take
|
|
|
|
* it out of promiscuous mode.
|
|
|
|
*
|
|
|
|
* XXX - if somebody else wants it in promiscuous mode,
|
|
|
|
* this code cannot know that, so it'll take it out
|
|
|
|
* of promiscuous mode. That's not fixable in 2.0[.x]
|
|
|
|
* kernels.
|
|
|
|
*/
|
1997-05-27 00:01:12 +00:00
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
2001-04-03 04:18:09 +00:00
|
|
|
strncpy(ifr.ifr_name, handle->md.device, sizeof(ifr.ifr_name));
|
|
|
|
if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
|
|
|
|
fprintf(stderr,
|
|
|
|
"Can't restore interface flags (SIOCGIFFLAGS failed: %s).\n"
|
|
|
|
"Please adjust manually.\n"
|
|
|
|
"Hint: This can't happen with Linux >= 2.2.0.\n",
|
|
|
|
strerror(errno));
|
|
|
|
} else {
|
|
|
|
if (ifr.ifr_flags & IFF_PROMISC) {
|
|
|
|
/*
|
|
|
|
* Promiscuous mode is currently on; turn it
|
|
|
|
* off.
|
|
|
|
*/
|
|
|
|
ifr.ifr_flags &= ~IFF_PROMISC;
|
|
|
|
if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
|
|
|
|
fprintf(stderr,
|
|
|
|
"Can't restore interface flags (SIOCSIFFLAGS failed: %s).\n"
|
|
|
|
"Please adjust manually.\n"
|
|
|
|
"Hint: This can't happen with Linux >= 2.2.0.\n",
|
|
|
|
strerror(errno));
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Take this pcap out of the list of pcaps for which we
|
|
|
|
* have to take the interface out of promiscuous mode.
|
|
|
|
*/
|
|
|
|
for (p = pcaps_to_close, prevp = NULL; p != NULL;
|
|
|
|
prevp = p, p = p->md.next) {
|
|
|
|
if (p == handle) {
|
|
|
|
/*
|
|
|
|
* Found it. Remove it from the list.
|
|
|
|
*/
|
|
|
|
if (prevp == NULL) {
|
|
|
|
/*
|
|
|
|
* It was at the head of the list.
|
|
|
|
*/
|
|
|
|
pcaps_to_close = p->md.next;
|
|
|
|
} else {
|
|
|
|
/*
|
|
|
|
* It was in the middle of the list.
|
|
|
|
*/
|
|
|
|
prevp->md.next = p->md.next;
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
if (handle->md.device != NULL)
|
|
|
|
free(handle->md.device);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Try to open a packet socket using the old kernel interface.
|
|
|
|
* Returns 0 on failure.
|
|
|
|
* FIXME: 0 uses to mean success (Sebastian)
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
live_open_old(pcap_t *handle, char *device, int promisc,
|
|
|
|
int to_ms, char *ebuf)
|
|
|
|
{
|
2002-06-21 01:36:27 +00:00
|
|
|
int sock_fd = -1, arptype;
|
2001-04-03 04:18:09 +00:00
|
|
|
struct ifreq ifr;
|
|
|
|
|
|
|
|
do {
|
|
|
|
/* Open the socket */
|
|
|
|
|
|
|
|
sock_fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
|
|
|
|
if (sock_fd == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"socket: %s", pcap_strerror(errno));
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* It worked - we are using the old interface */
|
|
|
|
handle->md.sock_packet = 1;
|
|
|
|
|
|
|
|
/* ...which means we get the link-layer header. */
|
|
|
|
handle->md.cooked = 0;
|
|
|
|
|
|
|
|
/* Bind to the given device */
|
|
|
|
|
|
|
|
if (!device) {
|
|
|
|
strncpy(ebuf, "pcap_open_live: The \"any\" device isn't supported on 2.0[.x]-kernel systems",
|
|
|
|
PCAP_ERRBUF_SIZE);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
if (iface_bind_old(sock_fd, device, ebuf) == -1)
|
|
|
|
break;
|
|
|
|
|
|
|
|
/* Go to promisc mode */
|
|
|
|
if (promisc) {
|
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
|
|
|
if (ioctl(sock_fd, SIOCGIFFLAGS, &ifr) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"ioctl: %s", pcap_strerror(errno));
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
if ((ifr.ifr_flags & IFF_PROMISC) == 0) {
|
|
|
|
/*
|
|
|
|
* Promiscuous mode isn't currently on,
|
|
|
|
* so turn it on, and remember that
|
|
|
|
* we should turn it off when the
|
|
|
|
* pcap_t is closed.
|
|
|
|
*/
|
|
|
|
|
|
|
|
/*
|
|
|
|
* If we haven't already done so, arrange
|
|
|
|
* to have "pcap_close_all()" called when
|
|
|
|
* we exit.
|
|
|
|
*/
|
|
|
|
if (!did_atexit) {
|
|
|
|
if (atexit(pcap_close_all) == -1) {
|
|
|
|
/*
|
|
|
|
* "atexit()" failed; don't
|
|
|
|
* put the interface in
|
|
|
|
* promiscuous mode, just
|
|
|
|
* give up.
|
|
|
|
*/
|
|
|
|
strncpy(ebuf, "atexit failed",
|
|
|
|
PCAP_ERRBUF_SIZE);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
ifr.ifr_flags |= IFF_PROMISC;
|
|
|
|
if (ioctl(sock_fd, SIOCSIFFLAGS, &ifr) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"ioctl: %s",
|
|
|
|
pcap_strerror(errno));
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
handle->md.clear_promisc = 1;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Add this to the list of pcaps
|
|
|
|
* to close when we exit.
|
|
|
|
*/
|
|
|
|
handle->md.next = pcaps_to_close;
|
|
|
|
pcaps_to_close = handle;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/* All done - fill in the pcap handle */
|
|
|
|
|
|
|
|
arptype = iface_get_arptype(sock_fd, device, ebuf);
|
|
|
|
if (arptype == -1)
|
|
|
|
break;
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
/* Save the socket FD in the pcap structure */
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
handle->fd = sock_fd;
|
2002-06-21 01:36:27 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Default value for offset to align link-layer payload
|
|
|
|
* on a 4-byte boundary.
|
|
|
|
*/
|
2001-04-03 04:18:09 +00:00
|
|
|
handle->offset = 0;
|
2002-06-21 01:36:27 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* XXX - handle ISDN types here? We can't fall back on
|
|
|
|
* cooked sockets, so we'd have to figure out from the
|
|
|
|
* device name what type of link-layer encapsulation
|
|
|
|
* it's using, and map that to an appropriate DLT_
|
|
|
|
* value, meaning we'd map "isdnN" devices to DLT_RAW
|
|
|
|
* (they supply raw IP packets with no link-layer
|
|
|
|
* header) and "isdY" devices to a new DLT_I4L_IP
|
|
|
|
* type that has only an Ethernet packet type as
|
|
|
|
* a link-layer header.
|
|
|
|
*/
|
2002-06-21 01:36:27 +00:00
|
|
|
map_arphrd_to_dlt(handle, arptype);
|
|
|
|
if (handle->linktype == -1 ||
|
|
|
|
handle->linktype == DLT_LINUX_SLL) {
|
2001-04-03 04:18:09 +00:00
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"interface type of %s not supported", device);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
return 1;
|
|
|
|
|
|
|
|
} while (0);
|
|
|
|
|
|
|
|
if (sock_fd != -1)
|
|
|
|
close(sock_fd);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Bind the socket associated with FD to the given device using the
|
|
|
|
* interface of the old kernels.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
iface_bind_old(int fd, const char *device, char *ebuf)
|
|
|
|
{
|
|
|
|
struct sockaddr saddr;
|
|
|
|
|
|
|
|
memset(&saddr, 0, sizeof(saddr));
|
|
|
|
strncpy(saddr.sa_data, device, sizeof(saddr.sa_data));
|
|
|
|
if (bind(fd, &saddr, sizeof(saddr)) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"bind: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
/* ===== System calls available on all supported kernels ============== */
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Query the kernel for the MTU of the given interface.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
iface_get_mtu(int fd, const char *device, char *ebuf)
|
|
|
|
{
|
|
|
|
struct ifreq ifr;
|
|
|
|
|
|
|
|
if (!device)
|
|
|
|
return BIGGER_THAN_ALL_MTUS;
|
|
|
|
|
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
|
|
|
|
|
|
|
if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"ioctl: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
return ifr.ifr_mtu;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
/*
|
|
|
|
* Get the hardware type of the given interface as ARPHRD_xxx constant.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
iface_get_arptype(int fd, const char *device, char *ebuf)
|
1997-05-27 00:01:12 +00:00
|
|
|
{
|
2001-04-03 04:18:09 +00:00
|
|
|
struct ifreq ifr;
|
1997-05-27 00:01:12 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
|
|
strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
|
|
|
|
|
|
|
|
if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) {
|
|
|
|
snprintf(ebuf, PCAP_ERRBUF_SIZE,
|
|
|
|
"ioctl: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
|
|
return ifr.ifr_hwaddr.sa_family;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
|
|
|
|
2002-06-21 01:36:27 +00:00
|
|
|
#ifdef SO_ATTACH_FILTER
|
2001-04-03 04:18:09 +00:00
|
|
|
static int
|
|
|
|
fix_program(pcap_t *handle, struct sock_fprog *fcode)
|
1997-05-27 00:01:12 +00:00
|
|
|
{
|
2001-04-03 04:18:09 +00:00
|
|
|
size_t prog_size;
|
|
|
|
register int i;
|
|
|
|
register struct bpf_insn *p;
|
|
|
|
struct bpf_insn *f;
|
|
|
|
int len;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Make a copy of the filter, and modify that copy if
|
|
|
|
* necessary.
|
|
|
|
*/
|
|
|
|
prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len;
|
|
|
|
len = handle->fcode.bf_len;
|
|
|
|
f = (struct bpf_insn *)malloc(prog_size);
|
|
|
|
if (f == NULL) {
|
|
|
|
snprintf(handle->errbuf, sizeof(handle->errbuf),
|
|
|
|
"malloc: %s", pcap_strerror(errno));
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
memcpy(f, handle->fcode.bf_insns, prog_size);
|
|
|
|
fcode->len = len;
|
|
|
|
fcode->filter = (struct sock_filter *) f;
|
|
|
|
|
|
|
|
for (i = 0; i < len; ++i) {
|
|
|
|
p = &f[i];
|
|
|
|
/*
|
|
|
|
* What type of instruction is this?
|
|
|
|
*/
|
|
|
|
switch (BPF_CLASS(p->code)) {
|
|
|
|
|
|
|
|
case BPF_RET:
|
|
|
|
/*
|
|
|
|
* It's a return instruction; is the snapshot
|
|
|
|
* length a constant, rather than the contents
|
|
|
|
* of the accumulator?
|
|
|
|
*/
|
|
|
|
if (BPF_MODE(p->code) == BPF_K) {
|
|
|
|
/*
|
|
|
|
* Yes - if the value to be returned,
|
|
|
|
* i.e. the snapshot length, is anything
|
|
|
|
* other than 0, make it 65535, so that
|
|
|
|
* the packet is truncated by "recvfrom()",
|
|
|
|
* not by the filter.
|
|
|
|
*
|
|
|
|
* XXX - there's nothing we can easily do
|
|
|
|
* if it's getting the value from the
|
|
|
|
* accumulator; we'd have to insert
|
|
|
|
* code to force non-zero values to be
|
|
|
|
* 65535.
|
|
|
|
*/
|
|
|
|
if (p->k != 0)
|
|
|
|
p->k = 65535;
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
|
|
|
|
case BPF_LD:
|
|
|
|
case BPF_LDX:
|
|
|
|
/*
|
|
|
|
* It's a load instruction; is it loading
|
|
|
|
* from the packet?
|
|
|
|
*/
|
|
|
|
switch (BPF_MODE(p->code)) {
|
1997-05-27 00:01:12 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
case BPF_ABS:
|
|
|
|
case BPF_IND:
|
|
|
|
case BPF_MSH:
|
|
|
|
/*
|
|
|
|
* Yes; are we in cooked mode?
|
|
|
|
*/
|
|
|
|
if (handle->md.cooked) {
|
|
|
|
/*
|
|
|
|
* Yes, so we need to fix this
|
|
|
|
* instruction.
|
|
|
|
*/
|
|
|
|
if (fix_offset(p) < 0) {
|
|
|
|
/*
|
|
|
|
* We failed to do so.
|
|
|
|
* Return 0, so our caller
|
|
|
|
* knows to punt to userland.
|
|
|
|
*/
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return 1; /* we succeeded */
|
|
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
|
|
fix_offset(struct bpf_insn *p)
|
|
|
|
{
|
|
|
|
/*
|
|
|
|
* What's the offset?
|
|
|
|
*/
|
|
|
|
if (p->k >= SLL_HDR_LEN) {
|
|
|
|
/*
|
|
|
|
* It's within the link-layer payload; that starts at an
|
|
|
|
* offset of 0, as far as the kernel packet filter is
|
|
|
|
* concerned, so subtract the length of the link-layer
|
|
|
|
* header.
|
|
|
|
*/
|
|
|
|
p->k -= SLL_HDR_LEN;
|
|
|
|
} else if (p->k == 14) {
|
|
|
|
/*
|
|
|
|
* It's the protocol field; map it to the special magic
|
|
|
|
* kernel offset for that field.
|
|
|
|
*/
|
|
|
|
p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
|
|
|
|
} else {
|
|
|
|
/*
|
|
|
|
* It's within the header, but it's not one of those
|
|
|
|
* fields; we can't do that in the kernel, so punt
|
|
|
|
* to userland.
|
|
|
|
*/
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
return 0;
|
1997-05-27 00:01:12 +00:00
|
|
|
}
|
2002-06-21 01:36:27 +00:00
|
|
|
|
|
|
|
static int
|
|
|
|
set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode)
|
|
|
|
{
|
|
|
|
int total_filter_on = 0;
|
|
|
|
int save_mode;
|
|
|
|
int ret;
|
|
|
|
int save_errno;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* The socket filter code doesn't discard all packets queued
|
|
|
|
* up on the socket when the filter is changed; this means
|
|
|
|
* that packets that don't match the new filter may show up
|
|
|
|
* after the new filter is put onto the socket, if those
|
|
|
|
* packets haven't yet been read.
|
|
|
|
*
|
|
|
|
* This means, for example, that if you do a tcpdump capture
|
|
|
|
* with a filter, the first few packets in the capture might
|
|
|
|
* be packets that wouldn't have passed the filter.
|
|
|
|
*
|
|
|
|
* We therefore discard all packets queued up on the socket
|
|
|
|
* when setting a kernel filter. (This isn't an issue for
|
|
|
|
* userland filters, as the userland filtering is done after
|
|
|
|
* packets are queued up.)
|
|
|
|
*
|
|
|
|
* To flush those packets, we put the socket in read-only mode,
|
|
|
|
* and read packets from the socket until there are no more to
|
|
|
|
* read.
|
|
|
|
*
|
|
|
|
* In order to keep that from being an infinite loop - i.e.,
|
|
|
|
* to keep more packets from arriving while we're draining
|
|
|
|
* the queue - we put the "total filter", which is a filter
|
|
|
|
* that rejects all packets, onto the socket before draining
|
|
|
|
* the queue.
|
|
|
|
*
|
|
|
|
* This code deliberately ignores any errors, so that you may
|
|
|
|
* get bogus packets if an error occurs, rather than having
|
|
|
|
* the filtering done in userland even if it could have been
|
|
|
|
* done in the kernel.
|
|
|
|
*/
|
|
|
|
if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
|
|
|
|
&total_fcode, sizeof(total_fcode)) == 0) {
|
|
|
|
char drain[1];
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Note that we've put the total filter onto the socket.
|
|
|
|
*/
|
|
|
|
total_filter_on = 1;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Save the socket's current mode, and put it in
|
|
|
|
* non-blocking mode; we drain it by reading packets
|
|
|
|
* until we get an error (which we assume is a
|
|
|
|
* "nothing more to be read" error).
|
|
|
|
*/
|
|
|
|
save_mode = fcntl(handle->fd, F_GETFL, 0);
|
|
|
|
if (save_mode != -1 &&
|
|
|
|
fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) {
|
|
|
|
while (recv(handle->fd, &drain, sizeof drain,
|
|
|
|
MSG_TRUNC) >= 0)
|
|
|
|
;
|
|
|
|
fcntl(handle->fd, F_SETFL, save_mode);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Now attach the new filter.
|
|
|
|
*/
|
|
|
|
ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
|
|
|
|
fcode, sizeof(*fcode));
|
|
|
|
if (ret == -1 && total_filter_on) {
|
|
|
|
/*
|
|
|
|
* Well, we couldn't set that filter on the socket,
|
|
|
|
* but we could set the total filter on the socket.
|
|
|
|
*
|
|
|
|
* This could, for example, mean that the filter was
|
|
|
|
* too big to put into the kernel, so we'll have to
|
|
|
|
* filter in userland; in any case, we'll be doing
|
|
|
|
* filtering in userland, so we need to remove the
|
|
|
|
* total filter so we see packets.
|
|
|
|
*/
|
|
|
|
save_errno = errno;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* XXX - if this fails, we're really screwed;
|
|
|
|
* we have the total filter on the socket,
|
|
|
|
* and it won't come off. What do we do then?
|
|
|
|
*/
|
|
|
|
reset_kernel_filter(handle);
|
|
|
|
|
|
|
|
errno = save_errno;
|
|
|
|
}
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
|
|
reset_kernel_filter(pcap_t *handle)
|
|
|
|
{
|
|
|
|
/* setsockopt() barfs unless it get a dummy parameter */
|
|
|
|
int dummy;
|
|
|
|
|
|
|
|
return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
|
|
|
|
&dummy, sizeof(dummy));
|
|
|
|
}
|
2001-04-03 04:18:09 +00:00
|
|
|
#endif
|