diff options
Diffstat (limited to 'contrib/libpcap/pcap-linux.c')
-rw-r--r-- | contrib/libpcap/pcap-linux.c | 1545 |
1 files changed, 1290 insertions, 255 deletions
diff --git a/contrib/libpcap/pcap-linux.c b/contrib/libpcap/pcap-linux.c index 17e0a3b..1199f8f 100644 --- a/contrib/libpcap/pcap-linux.c +++ b/contrib/libpcap/pcap-linux.c @@ -1,331 +1,1366 @@ /* - * Copyright (c) 1996, 1997 - * The Regents of the University of California. All rights reserved. + * pcap-linux.c: Packet capture interface to the Linux kernel * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that: (1) source code distributions - * retain the above copyright notice and this paragraph in its entirety, (2) - * distributions including binary code include the above copyright notice and - * this paragraph in its entirety in the documentation or other materials - * provided with the distribution, and (3) all advertising materials mentioning - * features or use of this software display the following acknowledgement: - * ``This product includes software developed by the University of California, - * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of - * the University nor the names of its contributors may be used to endorse - * or promote products derived from this software without specific prior - * written permission. - * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED - * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF - * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. + * Copyright (c) 2000 Torsten Landschoff <torsten@debian.org> + * Sebastian Krahmer <krahmer@cs.uni-potsdam.de> + * + * License: BSD + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. The names of the authors may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. */ #ifndef lint static const char rcsid[] = - "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.15.1.1 1999/10/07 23:46:40 mcr Exp $ (LBL)"; + "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.51.2.3 2001/01/18 03:59:56 guy Exp $ (LBL)"; #endif -#include <sys/param.h> -#include <sys/ioctl.h> -#include <sys/socket.h> -#include <sys/time.h> +/* + * Known problems with 2.0[.x] kernels: + * + * - The loopback device gives every packet twice; on 2.2[.x] kernels, + * if we use PF_PACKET, we can filter out the transmitted version + * of the packet by using data in the "sockaddr_ll" returned by + * "recvfrom()", but, on 2.0[.x] kernels, we have to use + * PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a + * "sockaddr_pkt" which doesn't give us enough information to let + * us do that. + * + * - We have to set the interface's IFF_PROMISC flag ourselves, if + * we're to run in promiscuous mode, which means we have to turn + * it off ourselves when we're done; the kernel doesn't keep track + * of how many sockets are listening promiscuously, which means + * it won't get turned off automatically when no sockets are + * listening promiscuously. We catch "pcap_close()" and, for + * interfaces we put into promiscuous mode, take them out of + * promiscuous mode - which isn't necessarily the right thing to + * do, if another socket also requested promiscuous mode between + * the time when we opened the socket and the time when we close + * the socket. + */ -#include <net/if.h> -#ifdef HAVE_NET_IF_ARP_H -#include <net/if_arp.h> -#else -#include <linux/if_arp.h> + +#ifdef HAVE_CONFIG_H +#include "config.h" #endif -#include <linux/if_ether.h> -#include <netinet/in.h> +#include "pcap-int.h" +#include "sll.h" #include <errno.h> -#include <malloc.h> -#include <stdio.h> #include <stdlib.h> -#include <string.h> #include <unistd.h> +#include <fcntl.h> +#include <string.h> +#include <sys/socket.h> +#include <sys/ioctl.h> +#include <sys/utsname.h> +#include <net/if.h> +#include <netinet/in.h> +#include <linux/if_ether.h> +#include <net/if_arp.h> -static struct ifreq saved_ifr; +#ifdef HAVE_NETPACKET_PACKET_H +# include <netpacket/packet.h> -#include "pcap-int.h" + /* + * We assume this means we really do have PF_PACKET sockets. + */ +# define HAVE_PF_PACKET_SOCKETS +#else + /* + * Oh, joy. Some Linux distributions have 2.2 or later kernels and + * libc5. On at least one of those systems (Slackware 4.0), it + * appears that "/usr/include/sys/socket.h" includes <linux/socket.h>, + * which means it picks up all the AF_, PF_, and SO_ definitions + * appropriate for the current kernel; however, it also appears that + * they did not see fit to provide a "/usr/include/netpacket/packet.h" + * file. + * + * However, you should be able to get the right definitions by including + * <linux/if_packet.h>. + * + * So if this system has PF_PACKET defined but doesn't have the + * <netpacket/packet.h> header file, we include <linux/if_packet.h> + * instead. + */ +# ifdef PF_PACKET +# include <linux/if_packet.h> -#include "gnuc.h" -#ifdef HAVE_OS_PROTO_H -#include "os-proto.h" + /* + * However, on at least some Linux distributions (for example, Red Hat + * 5.2), there's no <netpacket/packet.h> file, but PF_PACKET is defined + * if you include <sys/socket.h>, but <linux/if_packet.h> doesn't define + * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of + * the PACKET_xxx stuff. + * + * So we check whether PACKET_HOST is defined, and assume that we have + * PF_PACKET sockets only if it is defined. + */ +# ifdef PACKET_HOST +# define HAVE_PF_PACKET_SOCKETS +# endif /* PACKET_HOST */ +# endif /* PF_PACKET */ +#endif /* HAVE_NETPACKET_PACKET_H */ + +#ifdef SO_ATTACH_FILTER +#include <linux/types.h> +#include <linux/filter.h> #endif -void linux_restore_ifr(void); +#ifndef __GLIBC__ +typedef int socklen_t; +#endif -int -pcap_stats(pcap_t *p, struct pcap_stat *ps) +#ifndef MSG_TRUNC +#define MSG_TRUNC 0 +#endif + +#define MAX_LINKHEADER_SIZE 256 + +/* + * When capturing on all interfaces we use this as the buffer size. + * Should be bigger then all MTUs that occur in real life. + * 64kB should be enough for now. + */ +#define BIGGER_THAN_ALL_MTUS (64*1024) + +/* + * Prototypes for internal functions + */ +static int map_arphrd_to_dlt(int arptype ); +static int live_open_old(pcap_t *, char *, int, int, char *); +static int live_open_new(pcap_t *, char *, int, int, char *); +static int pcap_read_packet(pcap_t *, pcap_handler, u_char *); + +/* + * Wrap some ioctl calls + */ +#ifdef HAVE_PF_PACKET_SOCKETS +static int iface_get_id(int fd, const char *device, char *ebuf); +#endif +static int iface_get_mtu(int fd, const char *device, char *ebuf); +static int iface_get_arptype(int fd, const char *device, char *ebuf); +#ifdef HAVE_PF_PACKET_SOCKETS +static int iface_bind(int fd, int ifindex, char *ebuf); +#endif +static int iface_bind_old(int fd, const char *device, char *ebuf); + +#ifdef SO_ATTACH_FILTER +static int fix_program(pcap_t *handle, struct sock_fprog *fcode); +static int fix_offset(struct bpf_insn *p); +#endif + +/* + * Get a handle for a live capture from the given device. You can + * pass NULL as device to get all packages (without link level + * information of course). If you pass 1 as promisc the interface + * will be set to promiscous mode (XXX: I think this usage should + * be deprecated and functions be added to select that later allow + * modification of that values -- Torsten). + * + * See also pcap(3). + */ +pcap_t * +pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf) { + /* Allocate a handle for this session. */ + + pcap_t *handle = malloc(sizeof(*handle)); + if (handle == NULL) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s", + pcap_strerror(errno)); + return NULL; + } + + /* Initialize some components of the pcap structure. */ + + memset(handle, 0, sizeof(*handle)); + handle->snapshot = snaplen; + handle->md.timeout = to_ms; + + /* + * NULL and "any" are special devices which give us the hint to + * monitor all devices. + */ + if (!device || strcmp(device, "any") == 0) { + device = NULL; + handle->md.device = strdup("any"); + } else + handle->md.device = strdup(device); + + if (handle->md.device == NULL) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, "strdup: %s", + pcap_strerror(errno) ); + free(handle); + return NULL; + } + + /* + * 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). + */ - *ps = p->md.stat; - return (0); + free(handle->md.device); + free(handle); + return NULL; + } + + return handle; } +/* + * 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. + */ int -pcap_read(pcap_t *p, int cnt, pcap_handler callback, u_char *user) +pcap_read(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) { - register int cc; - register int bufsize; - register int caplen; - register u_char *bp; - struct sockaddr from; - int fromlen; - - bp = p->buffer + p->offset; - bufsize = p->bufsize; - if (p->md.pad > 0) { - memset(bp, 0, p->md.pad); - bp += p->md.pad; - bufsize -= p->md.pad; - } + /* + * 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) +{ + 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 */ -again: do { fromlen = sizeof(from); - cc = recvfrom(p->fd, bp, bufsize, 0, &from, &fromlen); - if (cc < 0) { - /* Don't choke when we get ptraced */ - switch (errno) { + packet_len = recvfrom( + handle->fd, handle->buffer + offset + handle->offset, + handle->md.readlen - offset, MSG_TRUNC, + (struct sockaddr *) &from, &fromlen); + } while (packet_len == -1 && errno == EINTR); - case EINTR: - goto again; + /* Check if an error occured */ - case EWOULDBLOCK: - return (0); /* XXX */ - } - sprintf(p->errbuf, "read: %s", pcap_strerror(errno)); - return (-1); + 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; } - } while (strcmp(p->md.device, from.sa_data)); - - /* If we need have leading zero bytes, adjust count */ - cc += p->md.pad; - bp = p->buffer + p->offset; - - /* If we need to step over leading junk, adjust count and pointer */ - cc -= p->md.skip; - bp += p->md.skip; - - /* Captured length can't exceed our read buffer size */ - caplen = cc; - if (caplen > bufsize) - caplen = bufsize; - - /* Captured length can't exceed the snapshot length */ - if (caplen > p->snapshot) - caplen = p->snapshot; - - if (p->fcode.bf_insns == NULL || - bpf_filter(p->fcode.bf_insns, bp, cc, caplen)) { - struct pcap_pkthdr h; - - ++p->md.stat.ps_recv; - /* Get timestamp */ - if (ioctl(p->fd, SIOCGSTAMP, &h.ts) < 0) { - sprintf(p->errbuf, "SIOCGSTAMP: %s", - pcap_strerror(errno)); - return (-1); + } + +#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; + + hdrp = (struct sll_header *)handle->buffer; + + /* + * 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) { + if (bpf_filter(handle->fcode.bf_insns, handle->buffer, + packet_len, caplen) == 0) + { + /* rejected by filter */ + return 0; } - h.len = cc; - h.caplen = caplen; - (*callback)(user, &h, bp); - return (1); } - return (0); + + /* 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; + + /* Call the user supplied callback function */ + handle->md.stat.ps_recv++; + callback(userdata, &pcap_header, handle->buffer + handle->offset); + + return 1; } -pcap_t * -pcap_open_live(char *device, int snaplen, int promisc, int to_ms, char *ebuf) +/* + * Get the statistics for the given packet capture handle. + * FIXME: Currently does not report the number of dropped packets. + */ +int +pcap_stats(pcap_t *handle, struct pcap_stat *stats) { - register int fd, broadcast; - register pcap_t *p; - struct ifreq ifr; - struct sockaddr sa; - - p = (pcap_t *)malloc(sizeof(*p)); - if (p == NULL) { - sprintf(ebuf, "malloc: %s", pcap_strerror(errno)); - return (NULL); + *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; } - memset(p, 0, sizeof(*p)); - fd = -1; - fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL)); - if (fd < 0) { - sprintf(ebuf, "socket: %s", pcap_strerror(errno)); - goto bad; + /* 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; } - p->fd = fd; - - /* Bind to the interface name */ - memset(&sa, 0, sizeof(sa)); - sa.sa_family = AF_INET; - (void)strncpy(sa.sa_data, device, sizeof(sa.sa_data)); - if (bind(p->fd, &sa, sizeof(sa))) { - sprintf(ebuf, "bind: %s: %s", device, pcap_strerror(errno)); - goto bad; + + /* + * 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; + } } - memset(&ifr, 0, sizeof(ifr)); - strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); - if (ioctl(p->fd, SIOCGIFHWADDR, &ifr) < 0 ) { - sprintf(ebuf, "SIOCGIFHWADDR: %s", pcap_strerror(errno)); - goto bad; + if (can_filter_in_kernel) { + if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER, + &fcode, sizeof(fcode)) == 0) + { + /* 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)); + } + } } - broadcast = 0; - switch (ifr.ifr_hwaddr.sa_family) { + /* + * 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 + * function maps the ARPHRD_xxx constant to an appropriate + * DLT_xxx constant. + * + * Returns -1 if unable to map the type; we print a message and, + * if we're using PF_PACKET/SOCK_RAW rather than PF_INET/SOCK_PACKET, + * we fall back on using PF_PACKET/SOCK_DGRAM. + */ +static int map_arphrd_to_dlt(int arptype) +{ + switch (arptype) { case ARPHRD_ETHER: case ARPHRD_METRICOM: - p->linktype = DLT_EN10MB; - p->offset = 2; - ++broadcast; - break; - - case ARPHRD_EETHER: - p->linktype = DLT_EN3MB; - ++broadcast; - break; - - case ARPHRD_AX25: - p->linktype = DLT_AX25; - ++broadcast; - break; - - case ARPHRD_PRONET: - p->linktype = DLT_PRONET; - break; - - case ARPHRD_CHAOS: - p->linktype = DLT_CHAOS; - break; - - case ARPHRD_IEEE802: - p->linktype = DLT_IEEE802; - ++broadcast; - break; - - case ARPHRD_ARCNET: - p->linktype = DLT_ARCNET; - ++broadcast; - break; - - case ARPHRD_SLIP: + case ARPHRD_LOOPBACK: return DLT_EN10MB; + case ARPHRD_EETHER: return DLT_EN3MB; + case ARPHRD_AX25: return DLT_AX25; + case ARPHRD_PRONET: return DLT_PRONET; + case ARPHRD_CHAOS: return DLT_CHAOS; +#ifndef ARPHRD_IEEE802_TR +#define ARPHRD_IEEE802_TR 800 /* From Linux 2.4 */ +#endif + case ARPHRD_IEEE802_TR: + case ARPHRD_IEEE802: return DLT_IEEE802; + case ARPHRD_ARCNET: return DLT_ARCNET; + case ARPHRD_FDDI: return DLT_FDDI; + +#ifndef ARPHRD_ATM /* FIXME: How to #include this? */ +#define ARPHRD_ATM 19 +#endif + case ARPHRD_ATM: return DLT_ATM_CLIP; + + case ARPHRD_PPP: + /* 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: case ARPHRD_CSLIP: case ARPHRD_SLIP6: case ARPHRD_CSLIP6: - case ARPHRD_PPP: - p->linktype = DLT_RAW; - break; - - case ARPHRD_LOOPBACK: - p->linktype = DLT_NULL; - p->md.pad = 2; - p->md.skip = 12; - break; - -#ifdef ARPHRD_FDDI - /* Not all versions of the kernel has this define */ - case ARPHRD_FDDI: - p->linktype = DLT_FDDI; - ++broadcast; - break; + case ARPHRD_SLIP: return DLT_RAW; + } + + return -1; +} + +/* ===== 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 + int sock_fd = -1, device_id, mtu, arptype; + 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); + + /* + * 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; + handle->linktype = map_arphrd_to_dlt(arptype); + if (handle->linktype == -1 || + (handle->linktype == DLT_EN10MB && + (strncmp("isdn", device, 4) == 0 || + strncmp("isdY", device, 4) == 0)) || + (handle->linktype == DLT_RAW && + (strncmp("ippp", device, 4) == 0))) { + /* + * Unknown interface type (-1), or an ISDN + * device (whose link-layer type we + * can only determine by using APIs + * that may be different on different + * kernels) - reopen in cooked mode. + * + * XXX - do that with DLT_RAW as well? + */ + 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. + */ + fprintf(stderr, + "Warning: arptype %d not " + "supported by libpcap - " + "falling back to cooked " + "socket\n", + 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; + } + } #endif -#ifdef notdef - case ARPHRD_LOCALTLK: - case ARPHRD_NETROM: - case ARPHRD_APPLETLK: - case ARPHRD_DLCI: - case ARPHRD_RSRVD: - case ARPHRD_ADAPT: - case ARPHRD_TUNNEL: - case ARPHRD_TUNNEL6: - case ARPHRD_FRAD: - case ARPHRD_SKIP: - /* XXX currently do not know what to do with these... */ - abort(); + /* Compute the buffersize */ + + mtu = iface_get_mtu(sock_fd, device, ebuf); + if (mtu == -1) + break; + handle->bufsize = MAX_LINKHEADER_SIZE + mtu; + + /* Fill in the pcap structure */ + + handle->fd = sock_fd; + handle->offset = 0; + + handle->buffer = malloc(handle->bufsize); + if (!handle->buffer) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "malloc: %s", pcap_strerror(errno)); + break; + } + + /* + * This is a 2.2 or later kernel, as it has PF_PACKET; + * "recvfrom()", when passed the MSG_TRUNC flag, will + * return the actual length of the packet, not the + * number of bytes from the packet copied to userland, + * so we can safely pass it a byte count based on the + * snapshot length. + */ + handle->md.readlen = handle->snapshot; + 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; #endif +} - default: - sprintf(ebuf, "unknown physical layer type 0x%x", - ifr.ifr_hwaddr.sa_family); - goto bad; - } +#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; - /* Base the buffer size on the interface MTU */ memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); - if (ioctl(p->fd, SIOCGIFMTU, &ifr) < 0 ) { - sprintf(ebuf, "SIOCGIFMTU: %s", pcap_strerror(errno)); - goto bad; + + if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "ioctl: %s", pcap_strerror(errno)); + return -1; } - /* Leave room for link header (which is never large under linux...) */ - p->bufsize = ifr.ifr_mtu + 64; + return ifr.ifr_ifindex; +} - p->buffer = (u_char *)malloc(p->bufsize + p->offset); - if (p->buffer == NULL) { - sprintf(ebuf, "malloc: %s", pcap_strerror(errno)); - goto bad; +/* + * 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; } - /* XXX */ - if (promisc && broadcast) { + 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. + */ memset(&ifr, 0, sizeof(ifr)); - strcpy(ifr.ifr_name, device); - if (ioctl(p->fd, SIOCGIFFLAGS, &ifr) < 0 ) { - sprintf(ebuf, "SIOCGIFFLAGS: %s", pcap_strerror(errno)); - goto bad; + 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) +{ + int sock_fd = -1, mtu, arptype; + struct utsname utsname; + 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; + } + } + + /* Compute the buffersize */ + + mtu = iface_get_mtu(sock_fd, device, ebuf); + if (mtu == -1) + break; + handle->bufsize = MAX_LINKHEADER_SIZE + mtu; + if (handle->bufsize < handle->snapshot) + handle->bufsize = handle->snapshot; + + /* All done - fill in the pcap handle */ + + arptype = iface_get_arptype(sock_fd, device, ebuf); + if (arptype == -1) + break; + + handle->fd = sock_fd; + handle->offset = 0; + handle->linktype = map_arphrd_to_dlt(arptype); + /* + * 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. + */ + if (handle->linktype == -1) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "interface type of %s not supported", device); + break; + } + handle->buffer = malloc(handle->bufsize); + if (!handle->buffer) { + snprintf(ebuf, PCAP_ERRBUF_SIZE, + "malloc: %s", pcap_strerror(errno)); + break; } - saved_ifr = ifr; - ifr.ifr_flags |= IFF_PROMISC; - if (ioctl(p->fd, SIOCSIFFLAGS, &ifr) < 0 ) { - sprintf(ebuf, "SIOCSIFFLAGS: %s", pcap_strerror(errno)); - goto bad; + + /* + * This might be a 2.0[.x] kernel - check. + */ + if (uname(&utsname) < 0 || + strncmp(utsname.release, "2.0", 3) == 0) { + /* + * 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. + * + * 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. + */ + handle->md.readlen = handle->bufsize; + } else { + /* + * This is a 2.2[.x] or later kernel (although + * why we're using SOCK_PACKET on such a system + * is unknown to me). + * + * We can safely pass "recvfrom()" a byte count + * based on the snapshot length. + */ + handle->md.readlen = handle->snapshot; } - ifr.ifr_flags &= ~IFF_PROMISC; - atexit(linux_restore_ifr); + 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; } - p->md.device = strdup(device); - if (p->md.device == NULL) { - sprintf(ebuf, "malloc: %s", pcap_strerror(errno)); - goto bad; + 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; } - p->snapshot = snaplen; - - return (p); -bad: - if (fd >= 0) - (void)close(fd); - if (p->buffer != NULL) - free(p->buffer); - if (p->md.device != NULL) - free(p->md.device); - free(p); - return (NULL); + + return ifr.ifr_mtu; } -int -pcap_setfilter(pcap_t *p, struct bpf_program *fp) +/* + * Get the hardware type of the given interface as ARPHRD_xxx constant. + */ +static int +iface_get_arptype(int fd, const char *device, char *ebuf) { + struct ifreq ifr; - p->fcode = *fp; - return (0); + 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; } -void -linux_restore_ifr(void) +#ifdef HAVE_PF_PACKET_SOCKETS +static int +fix_program(pcap_t *handle, struct sock_fprog *fcode) { - register int fd; + 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)) { - fd = socket(PF_INET, SOCK_PACKET, htons(0x0003)); - if (fd < 0) - fprintf(stderr, "linux socket: %s", pcap_strerror(errno)); - else if (ioctl(fd, SIOCSIFFLAGS, &saved_ifr) < 0) - fprintf(stderr, "linux SIOCSIFFLAGS: %s", pcap_strerror(errno)); + 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; } +#endif |