diff options
Diffstat (limited to 'lib/libpcap/libpcap/pcap-netfilter-linux.c')
-rw-r--r-- | lib/libpcap/libpcap/pcap-netfilter-linux.c | 761 |
1 files changed, 761 insertions, 0 deletions
diff --git a/lib/libpcap/libpcap/pcap-netfilter-linux.c b/lib/libpcap/libpcap/pcap-netfilter-linux.c new file mode 100644 index 0000000..91bad37 --- /dev/null +++ b/lib/libpcap/libpcap/pcap-netfilter-linux.c @@ -0,0 +1,761 @@ +/* + * Copyright (c) 2011 Jakub Zawadzki + * All rights reserved. + * + * 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 name of the author may not be used to endorse or promote + * products derived from this software without specific prior written + * permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif + +#include "pcap-int.h" + +#ifdef NEED_STRERROR_H +#include "strerror.h" +#endif + +#include <errno.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <sys/socket.h> +#include <arpa/inet.h> + +#include <time.h> +#include <sys/time.h> +#include <netinet/in.h> +#include <linux/types.h> + +#include <linux/netlink.h> +#include <linux/netfilter.h> +#include <linux/netfilter/nfnetlink.h> +#include <linux/netfilter/nfnetlink_log.h> +#include <linux/netfilter/nfnetlink_queue.h> + +/* NOTE: if your program drops privilages after pcap_activate() it WON'T work with nfqueue. + * It took me quite some time to debug ;/ + * + * Sending any data to nfnetlink socket requires CAP_NET_ADMIN privilages, + * and in nfqueue we need to send verdict reply after recving packet. + * + * In tcpdump you can disable dropping privilages with -Z root + */ + +#include "pcap-netfilter-linux.h" + +#define HDR_LENGTH (NLMSG_LENGTH(NLMSG_ALIGN(sizeof(struct nfgenmsg)))) + +#define NFLOG_IFACE "nflog" +#define NFQUEUE_IFACE "nfqueue" + +typedef enum { OTHER = -1, NFLOG, NFQUEUE } nftype_t; + +/* + * Private data for capturing on Linux netfilter sockets. + */ +struct pcap_netfilter { + u_int packets_read; /* count of packets read with recvfrom() */ + u_int packets_nobufs; /* ENOBUFS counter */ +}; + +static int nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict); + + +static int +netfilter_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user) +{ + struct pcap_netfilter *handlep = handle->priv; + register u_char *bp, *ep; + int count = 0; + int len; + + /* + * Has "pcap_breakloop()" been called? + */ + if (handle->break_loop) { + /* + * Yes - clear the flag that indicates that it + * has, and return PCAP_ERROR_BREAK to indicate + * that we were told to break out of the loop. + */ + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + len = handle->cc; + if (len == 0) { + /* + * The buffer is empty; refill it. + * + * We ignore EINTR, as that might just be due to a signal + * being delivered - if the signal should interrupt the + * loop, the signal handler should call pcap_breakloop() + * to set handle->break_loop (we ignore it on other + * platforms as well). + */ + do { + len = recv(handle->fd, handle->buffer, handle->bufsize, 0); + if (handle->break_loop) { + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } + if (errno == ENOBUFS) + handlep->packets_nobufs++; + } while ((len == -1) && (errno == EINTR || errno == ENOBUFS)); + + if (len < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "Can't receive packet"); + return PCAP_ERROR; + } + + bp = (unsigned char *)handle->buffer; + } else + bp = handle->bp; + ep = bp + len; + while (bp < ep) { + const struct nlmsghdr *nlh = (const struct nlmsghdr *) bp; + uint32_t msg_len; + nftype_t type = OTHER; + /* + * Has "pcap_breakloop()" been called? + * If so, return immediately - if we haven't read any + * packets, clear the flag and return PCAP_ERROR_BREAK + * to indicate that we were told to break out of the loop, + * otherwise leave the flag set, so that the *next* call + * will break out of the loop without having read any + * packets, and return the number of packets we've + * processed so far. + */ + if (handle->break_loop) { + handle->bp = bp; + handle->cc = ep - bp; + if (count == 0) { + handle->break_loop = 0; + return PCAP_ERROR_BREAK; + } else + return count; + } + if (ep - bp < NLMSG_SPACE(0)) { + /* + * There's less than one netlink message left + * in the buffer. Give up. + */ + break; + } + + if (nlh->nlmsg_len < sizeof(struct nlmsghdr) || (u_int)len < nlh->nlmsg_len) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %d) (nlmsg_len: %u)", len, nlh->nlmsg_len); + return -1; + } + + if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_ULOG && + NFNL_MSG_TYPE(nlh->nlmsg_type) == NFULNL_MSG_PACKET) + type = NFLOG; + else if (NFNL_SUBSYS_ID(nlh->nlmsg_type) == NFNL_SUBSYS_QUEUE && + NFNL_MSG_TYPE(nlh->nlmsg_type) == NFQNL_MSG_PACKET) + type = NFQUEUE; + + if (type != OTHER) { + const unsigned char *payload = NULL; + struct pcap_pkthdr pkth; + + const struct nfgenmsg *nfg = NULL; + int id = 0; + + if (handle->linktype != DLT_NFLOG) { + const struct nfattr *payload_attr = NULL; + + if (nlh->nlmsg_len < HDR_LENGTH) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Malformed message: (nlmsg_len: %u)", nlh->nlmsg_len); + return -1; + } + + nfg = NLMSG_DATA(nlh); + if (nlh->nlmsg_len > HDR_LENGTH) { + struct nfattr *attr = NFM_NFA(nfg); + int attr_len = nlh->nlmsg_len - NLMSG_ALIGN(HDR_LENGTH); + + while (NFA_OK(attr, attr_len)) { + if (type == NFQUEUE) { + switch (NFA_TYPE(attr)) { + case NFQA_PACKET_HDR: + { + const struct nfqnl_msg_packet_hdr *pkt_hdr = (const struct nfqnl_msg_packet_hdr *) NFA_DATA(attr); + + id = ntohl(pkt_hdr->packet_id); + break; + } + case NFQA_PAYLOAD: + payload_attr = attr; + break; + } + + } else if (type == NFLOG) { + switch (NFA_TYPE(attr)) { + case NFULA_PAYLOAD: + payload_attr = attr; + break; + } + } + attr = NFA_NEXT(attr, attr_len); + } + } + + if (payload_attr) { + payload = NFA_DATA(payload_attr); + pkth.len = pkth.caplen = NFA_PAYLOAD(payload_attr); + } + + } else { + payload = NLMSG_DATA(nlh); + pkth.caplen = pkth.len = nlh->nlmsg_len-NLMSG_ALIGN(sizeof(struct nlmsghdr)); + } + + if (payload) { + /* pkth.caplen = min (payload_len, handle->snapshot); */ + + gettimeofday(&pkth.ts, NULL); + if (handle->fcode.bf_insns == NULL || + bpf_filter(handle->fcode.bf_insns, payload, pkth.len, pkth.caplen)) + { + handlep->packets_read++; + callback(user, &pkth, payload); + count++; + } + } + + if (type == NFQUEUE) { + /* XXX, possible responses: NF_DROP, NF_ACCEPT, NF_STOLEN, NF_QUEUE, NF_REPEAT, NF_STOP */ + /* if type == NFQUEUE, handle->linktype is always != DLT_NFLOG, + so nfg is always initialized to NLMSG_DATA(nlh). */ + if (nfg != NULL) + nfqueue_send_verdict(handle, ntohs(nfg->res_id), id, NF_ACCEPT); + } + } + + msg_len = NLMSG_ALIGN(nlh->nlmsg_len); + /* + * If the message length would run past the end of the + * buffer, truncate it to the remaining space in the + * buffer. + */ + if (msg_len > ep - bp) + msg_len = ep - bp; + + bp += msg_len; + if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) { + handle->bp = bp; + handle->cc = ep - bp; + if (handle->cc < 0) + handle->cc = 0; + return count; + } + } + + handle->cc = 0; + return count; +} + +static int +netfilter_set_datalink(pcap_t *handle, int dlt) +{ + handle->linktype = dlt; + return 0; +} + +static int +netfilter_stats_linux(pcap_t *handle, struct pcap_stat *stats) +{ + struct pcap_netfilter *handlep = handle->priv; + + stats->ps_recv = handlep->packets_read; + stats->ps_drop = handlep->packets_nobufs; + stats->ps_ifdrop = 0; + return 0; +} + +static int +netfilter_inject_linux(pcap_t *handle, const void *buf _U_, size_t size _U_) +{ + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Packet injection is not supported on netfilter devices"); + return (-1); +} + +struct my_nfattr { + uint16_t nfa_len; + uint16_t nfa_type; + void *data; +}; + +static int +netfilter_send_config_msg(const pcap_t *handle, uint16_t msg_type, int ack, u_int8_t family, u_int16_t res_id, const struct my_nfattr *mynfa) +{ + char buf[1024] __attribute__ ((aligned)); + memset(buf, 0, sizeof(buf)); + + struct nlmsghdr *nlh = (struct nlmsghdr *) buf; + struct nfgenmsg *nfg = (struct nfgenmsg *) (buf + sizeof(struct nlmsghdr)); + + struct sockaddr_nl snl; + static unsigned int seq_id; + + if (!seq_id) + seq_id = time(NULL); + ++seq_id; + + nlh->nlmsg_len = NLMSG_LENGTH(sizeof(struct nfgenmsg)); + nlh->nlmsg_type = msg_type; + nlh->nlmsg_flags = NLM_F_REQUEST | (ack ? NLM_F_ACK : 0); + nlh->nlmsg_pid = 0; /* to kernel */ + nlh->nlmsg_seq = seq_id; + + nfg->nfgen_family = family; + nfg->version = NFNETLINK_V0; + nfg->res_id = htons(res_id); + + if (mynfa) { + struct nfattr *nfa = (struct nfattr *) (buf + NLMSG_ALIGN(nlh->nlmsg_len)); + + nfa->nfa_type = mynfa->nfa_type; + nfa->nfa_len = NFA_LENGTH(mynfa->nfa_len); + memcpy(NFA_DATA(nfa), mynfa->data, mynfa->nfa_len); + nlh->nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len) + NFA_ALIGN(nfa->nfa_len); + } + + memset(&snl, 0, sizeof(snl)); + snl.nl_family = AF_NETLINK; + + if (sendto(handle->fd, nlh, nlh->nlmsg_len, 0, (struct sockaddr *) &snl, sizeof(snl)) == -1) + return -1; + + if (!ack) + return 0; + + /* waiting for reply loop */ + do { + socklen_t addrlen = sizeof(snl); + int len; + + /* ignore interrupt system call error */ + do { + len = recvfrom(handle->fd, buf, sizeof(buf), 0, (struct sockaddr *) &snl, &addrlen); + } while ((len == -1) && (errno == EINTR)); + + if (len <= 0) + return len; + + if (addrlen != sizeof(snl) || snl.nl_family != AF_NETLINK) { + errno = EINVAL; + return -1; + } + + nlh = (struct nlmsghdr *) buf; + if (snl.nl_pid != 0 || seq_id != nlh->nlmsg_seq) /* if not from kernel or wrong sequence skip */ + continue; + + while ((u_int)len >= NLMSG_SPACE(0) && NLMSG_OK(nlh, (u_int)len)) { + if (nlh->nlmsg_type == NLMSG_ERROR || (nlh->nlmsg_type == NLMSG_DONE && nlh->nlmsg_flags & NLM_F_MULTI)) { + if (nlh->nlmsg_len < NLMSG_ALIGN(sizeof(struct nlmsgerr))) { + errno = EBADMSG; + return -1; + } + errno = -(*((int *)NLMSG_DATA(nlh))); + return (errno == 0) ? 0 : -1; + } + nlh = NLMSG_NEXT(nlh, len); + } + } while (1); + + return -1; /* never here */ +} + +static int +nflog_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) +{ + return netfilter_send_config_msg(handle, (NFNL_SUBSYS_ULOG << 8) | NFULNL_MSG_CONFIG, 1, family, group_id, mynfa); +} + +static int +nflog_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int8_t family) +{ + struct nfulnl_msg_config_cmd msg; + struct my_nfattr nfa; + + msg.command = cmd; + + nfa.data = &msg; + nfa.nfa_type = NFULA_CFG_CMD; + nfa.nfa_len = sizeof(msg); + + return nflog_send_config_msg(handle, family, group_id, &nfa); +} + +static int +nflog_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) +{ + struct nfulnl_msg_config_mode msg; + struct my_nfattr nfa; + + msg.copy_range = htonl(copy_range); + msg.copy_mode = copy_mode; + + nfa.data = &msg; + nfa.nfa_type = NFULA_CFG_MODE; + nfa.nfa_len = sizeof(msg); + + return nflog_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); +} + +static int +nfqueue_send_verdict(const pcap_t *handle, uint16_t group_id, u_int32_t id, u_int32_t verdict) +{ + struct nfqnl_msg_verdict_hdr msg; + struct my_nfattr nfa; + + msg.id = htonl(id); + msg.verdict = htonl(verdict); + + nfa.data = &msg; + nfa.nfa_type = NFQA_VERDICT_HDR; + nfa.nfa_len = sizeof(msg); + + return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_VERDICT, 0, AF_UNSPEC, group_id, &nfa); +} + +static int +nfqueue_send_config_msg(const pcap_t *handle, uint8_t family, u_int16_t group_id, const struct my_nfattr *mynfa) +{ + return netfilter_send_config_msg(handle, (NFNL_SUBSYS_QUEUE << 8) | NFQNL_MSG_CONFIG, 1, family, group_id, mynfa); +} + +static int +nfqueue_send_config_cmd(const pcap_t *handle, uint16_t group_id, u_int8_t cmd, u_int16_t pf) +{ + struct nfqnl_msg_config_cmd msg; + struct my_nfattr nfa; + + msg.command = cmd; + msg.pf = htons(pf); + + nfa.data = &msg; + nfa.nfa_type = NFQA_CFG_CMD; + nfa.nfa_len = sizeof(msg); + + return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); +} + +static int +nfqueue_send_config_mode(const pcap_t *handle, uint16_t group_id, u_int8_t copy_mode, u_int32_t copy_range) +{ + struct nfqnl_msg_config_params msg; + struct my_nfattr nfa; + + msg.copy_range = htonl(copy_range); + msg.copy_mode = copy_mode; + + nfa.data = &msg; + nfa.nfa_type = NFQA_CFG_PARAMS; + nfa.nfa_len = sizeof(msg); + + return nfqueue_send_config_msg(handle, AF_UNSPEC, group_id, &nfa); +} + +static int +netfilter_activate(pcap_t* handle) +{ + const char *dev = handle->opt.device; + unsigned short groups[32]; + int group_count = 0; + nftype_t type = OTHER; + int i; + + if (strncmp(dev, NFLOG_IFACE, strlen(NFLOG_IFACE)) == 0) { + dev += strlen(NFLOG_IFACE); + type = NFLOG; + + } else if (strncmp(dev, NFQUEUE_IFACE, strlen(NFQUEUE_IFACE)) == 0) { + dev += strlen(NFQUEUE_IFACE); + type = NFQUEUE; + } + + if (type != OTHER && *dev == ':') { + dev++; + while (*dev) { + long int group_id; + char *end_dev; + + if (group_count == 32) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Maximum 32 netfilter groups! dev: %s", + handle->opt.device); + return PCAP_ERROR; + } + + group_id = strtol(dev, &end_dev, 0); + if (end_dev != dev) { + if (group_id < 0 || group_id > 65535) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Netfilter group range from 0 to 65535 (got %ld)", + group_id); + return PCAP_ERROR; + } + + groups[group_count++] = (unsigned short) group_id; + dev = end_dev; + } + if (*dev != ',') + break; + dev++; + } + } + + if (type == OTHER || *dev) { + pcap_snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, + "Can't get netfilter group(s) index from %s", + handle->opt.device); + return PCAP_ERROR; + } + + /* if no groups, add default: 0 */ + if (!group_count) { + groups[0] = 0; + group_count = 1; + } + + /* + * Turn a negative snapshot value (invalid), a snapshot value of + * 0 (unspecified), or a value bigger than the normal maximum + * value, into the maximum allowed value. + * + * If some application really *needs* a bigger snapshot + * length, we should just increase MAXIMUM_SNAPLEN. + */ + if (handle->snapshot <= 0 || handle->snapshot > MAXIMUM_SNAPLEN) + handle->snapshot = MAXIMUM_SNAPLEN; + + /* Initialize some components of the pcap structure. */ + handle->bufsize = 128 + handle->snapshot; + handle->offset = 0; + handle->read_op = netfilter_read_linux; + handle->inject_op = netfilter_inject_linux; + handle->setfilter_op = install_bpf_program; /* no kernel filtering */ + handle->setdirection_op = NULL; + handle->set_datalink_op = netfilter_set_datalink; + handle->getnonblock_op = pcap_getnonblock_fd; + handle->setnonblock_op = pcap_setnonblock_fd; + handle->stats_op = netfilter_stats_linux; + + /* Create netlink socket */ + handle->fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); + if (handle->fd < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "Can't create raw socket"); + return PCAP_ERROR; + } + + if (type == NFLOG) { + handle->linktype = DLT_NFLOG; + handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2); + if (handle->dlt_list != NULL) { + handle->dlt_list[0] = DLT_NFLOG; + handle->dlt_list[1] = DLT_IPV4; + handle->dlt_count = 2; + } + + } else + handle->linktype = DLT_IPV4; + + handle->buffer = malloc(handle->bufsize); + if (!handle->buffer) { + pcap_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE, + errno, "Can't allocate dump buffer"); + goto close_fail; + } + + if (type == NFLOG) { + if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "NFULNL_CFG_CMD_PF_UNBIND"); + goto close_fail; + } + + if (nflog_send_config_cmd(handle, 0, NFULNL_CFG_CMD_PF_BIND, AF_INET) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "NFULNL_CFG_CMD_PF_BIND"); + goto close_fail; + } + + /* Bind socket to the nflog groups */ + for (i = 0; i < group_count; i++) { + if (nflog_send_config_cmd(handle, groups[i], NFULNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "Can't listen on group group index"); + goto close_fail; + } + + if (nflog_send_config_mode(handle, groups[i], NFULNL_COPY_PACKET, handle->snapshot) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "NFULNL_COPY_PACKET"); + goto close_fail; + } + } + + } else { + if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_UNBIND, AF_INET) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_UNBIND"); + goto close_fail; + } + + if (nfqueue_send_config_cmd(handle, 0, NFQNL_CFG_CMD_PF_BIND, AF_INET) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "NFQNL_CFG_CMD_PF_BIND"); + goto close_fail; + } + + /* Bind socket to the nfqueue groups */ + for (i = 0; i < group_count; i++) { + if (nfqueue_send_config_cmd(handle, groups[i], NFQNL_CFG_CMD_BIND, AF_UNSPEC) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "Can't listen on group group index"); + goto close_fail; + } + + if (nfqueue_send_config_mode(handle, groups[i], NFQNL_COPY_PACKET, handle->snapshot) < 0) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, + "NFQNL_COPY_PACKET"); + goto close_fail; + } + } + } + + if (handle->opt.rfmon) { + /* + * Monitor mode doesn't apply to netfilter devices. + */ + pcap_cleanup_live_common(handle); + return PCAP_ERROR_RFMON_NOTSUP; + } + + if (handle->opt.buffer_size != 0) { + /* + * Set the socket buffer size to the specified value. + */ + if (setsockopt(handle->fd, SOL_SOCKET, SO_RCVBUF, &handle->opt.buffer_size, sizeof(handle->opt.buffer_size)) == -1) { + pcap_fmt_errmsg_for_errno(handle->errbuf, + PCAP_ERRBUF_SIZE, errno, "SO_RCVBUF"); + goto close_fail; + } + } + + handle->selectable_fd = handle->fd; + return 0; + +close_fail: + pcap_cleanup_live_common(handle); + return PCAP_ERROR; +} + +pcap_t * +netfilter_create(const char *device, char *ebuf, int *is_ours) +{ + const char *cp; + pcap_t *p; + + /* Does this look like an netfilter device? */ + cp = strrchr(device, '/'); + if (cp == NULL) + cp = device; + + /* Does it begin with NFLOG_IFACE or NFQUEUE_IFACE? */ + if (strncmp(cp, NFLOG_IFACE, sizeof NFLOG_IFACE - 1) == 0) + cp += sizeof NFLOG_IFACE - 1; + else if (strncmp(cp, NFQUEUE_IFACE, sizeof NFQUEUE_IFACE - 1) == 0) + cp += sizeof NFQUEUE_IFACE - 1; + else { + /* Nope, doesn't begin with NFLOG_IFACE nor NFQUEUE_IFACE */ + *is_ours = 0; + return NULL; + } + + /* + * Yes - is that either the end of the name, or is it followed + * by a colon? + */ + if (*cp != ':' && *cp != '\0') { + /* Nope */ + *is_ours = 0; + return NULL; + } + + /* OK, it's probably ours. */ + *is_ours = 1; + + p = pcap_create_common(ebuf, sizeof (struct pcap_netfilter)); + if (p == NULL) + return (NULL); + + p->activate_op = netfilter_activate; + return (p); +} + +int +netfilter_findalldevs(pcap_if_list_t *devlistp, char *err_str) +{ + int sock; + + sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER); + if (sock < 0) { + /* if netlink is not supported this is not fatal */ + if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT) + return 0; + pcap_fmt_errmsg_for_errno(err_str, PCAP_ERRBUF_SIZE, + errno, "Can't open netlink socket"); + return -1; + } + close(sock); + + /* + * The notion of "connected" vs. "disconnected" doesn't apply. + * XXX - what about "up" and "running"? + */ + if (add_dev(devlistp, NFLOG_IFACE, + PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, + "Linux netfilter log (NFLOG) interface", err_str) == NULL) + return -1; + if (add_dev(devlistp, NFQUEUE_IFACE, + PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE, + "Linux netfilter queue (NFQUEUE) interface", err_str) == NULL) + return -1; + return 0; +} |