| /* |
| * pcap-linux.c: Packet capture interface to the Linux kernel |
| * |
| * 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 1.50 2000-12-23 07:50:18 guy Exp $ (LBL)"; |
| #endif |
| |
| /* |
| * 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. |
| */ |
| |
| |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| #include "pcap-int.h" |
| #include "sll.h" |
| |
| #include <errno.h> |
| #include <stdlib.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 <netinet/if_ether.h> |
| |
| #ifdef HAVE_NETPACKET_PACKET_H |
| #include <netpacket/packet.h> |
| #endif |
| #ifdef SO_ATTACH_FILTER |
| #include <linux/types.h> |
| #include <linux/filter.h> |
| #endif |
| |
| #ifndef __GLIBC__ |
| typedef int socklen_t; |
| #endif |
| |
| #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_NETPACKET_PACKET_H |
| 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_NETPACKET_PACKET_H |
| 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). |
| */ |
| |
| free(handle->md.device); |
| free(handle); |
| return NULL; |
| } |
| |
| /* |
| * Okay, now we have a packet stream open. Maybe we need to handle |
| * a timeout? In that case we set the filehandle to nonblocking |
| * so pcap_read can try reading the fd and call select if no data |
| * is available at first. |
| */ |
| |
| if (to_ms > 0) { |
| int flags = fcntl(handle->fd, F_GETFL); |
| if (flags != -1) { |
| flags |= O_NONBLOCK; |
| flags = fcntl(handle->fd, F_SETFL, flags); |
| } |
| if (flags == -1) { |
| snprintf(ebuf, PCAP_ERRBUF_SIZE, "fcntl: %s", |
| pcap_strerror(errno)); |
| pcap_close(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. |
| * |
| * XXX: Can I rely on the Linux-specified behaviour of select (returning |
| * the time left in the timeval structure)? I really don't want to query |
| * the system time before each select call... |
| * |
| * pcap_read currently gets not only a packet from the kernel but also |
| * the sockaddr_ll returned as source of the packet. This way we can at |
| * some time extend tcpdump and libpcap to sniff on all devices at a time |
| * and find the right printing routine by using the information in the |
| * sockaddr_ll structure. |
| */ |
| int |
| pcap_read(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) |
| { |
| int status, packets; |
| fd_set read_fds; |
| struct timeval tv; |
| |
| /* |
| * Fill in a timeval structure for select if we need to obeye a |
| * timeout. |
| */ |
| if (handle->md.timeout > 0) { |
| tv.tv_usec = (handle->md.timeout % 1000) * 1000; |
| tv.tv_sec = (handle->md.timeout / 1000); |
| } |
| |
| /* |
| * Read packets until the packet limit has been reached or |
| * an error occured while reading. Call the user function |
| * for each received packet. |
| */ |
| for (packets = 0; max_packets == -1 || packets < max_packets;) |
| { |
| status = pcap_read_packet(handle, callback, user); |
| |
| if (status > 0) { |
| packets += status; |
| continue; |
| } else if (status == -1) |
| return -1; |
| |
| /* |
| * If no packet is available we go to sleep. FIXME: This |
| * might be better implemented using poll(?) |
| */ |
| FD_ZERO(&read_fds); |
| FD_SET(handle->fd, &read_fds); |
| status = select(handle->fd + 1, |
| &read_fds, NULL, NULL, &tv); |
| |
| if (status == -1) { |
| if (errno == EINTR) |
| return packets; |
| snprintf(handle->errbuf, sizeof(handle->errbuf), |
| "select: %s", pcap_strerror(errno)); |
| return -1; |
| } |
| else if (status == 0 || |
| (tv.tv_usec == 0 && tv.tv_sec == 0)) |
| return packets; |
| } |
| |
| return packets; |
| } |
| |
| /* |
| * 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_NETPACKET_PACKET_H |
| 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_NETPACKET_PACKET_H |
| /* |
| * 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 */ |
| |
| do { |
| fromlen = sizeof(from); |
| 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); |
| |
| /* Check if an error occured */ |
| |
| 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; |
| } |
| } |
| |
| #ifdef HAVE_NETPACKET_PACKET_H |
| /* |
| * 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_NETPACKET_PACKET_H |
| /* |
| * 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; |
| } |
| } |
| |
| /* 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; |
| } |
| |
| /* |
| * 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) |
| { |
| *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; |
| } |
| |
| /* 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; |
| } |
| |
| /* |
| * 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; |
| } |
| } |
| |
| 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)); |
| } |
| } |
| } |
| |
| /* |
| * 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: |
| 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: |
| case ARPHRD_SIT: |
| case ARPHRD_CSLIP: |
| case ARPHRD_SLIP6: |
| case ARPHRD_CSLIP6: |
| 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_NETPACKET_PACKET_H |
| 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 |
| |
| /* 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 |
| } |
| |
| #ifdef HAVE_NETPACKET_PACKET_H |
| /* |
| * 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; |
| |
| memset(&ifr, 0, sizeof(ifr)); |
| strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name)); |
| |
| if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) { |
| snprintf(ebuf, PCAP_ERRBUF_SIZE, |
| "ioctl: %s", pcap_strerror(errno)); |
| return -1; |
| } |
| |
| return ifr.ifr_ifindex; |
| } |
| |
| /* |
| * 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; |
| } |
| |
| 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)); |
| 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; |
| } |
| |
| /* |
| * 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; |
| } |
| 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; |
| } |
| |
| 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; |
| } |
| |
| return ifr.ifr_mtu; |
| } |
| |
| /* |
| * 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; |
| |
| 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; |
| } |
| |
| #ifdef HAVE_NETPACKET_PACKET_H |
| static int |
| fix_program(pcap_t *handle, struct sock_fprog *fcode) |
| { |
| 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)) { |
| |
| 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 == 2) { |
| /* |
| * 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 |