pcap-netfilter-linux.c

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/*
 * 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 privileges 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 privileges,
 *       and in nfqueue we need to send verdict reply after recving packet.
 *
 *       In tcpdump you can disable dropping privileges 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;
    ssize_t 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 = (int)(ep - bp);
            if (count == 0) {
                handle->break_loop = 0;
                return PCAP_ERROR_BREAK;
            } else
                return count;
        }
        /*
         * NLMSG_SPACE(0) might be signed or might be unsigned,
         * depending on whether the kernel defines NLMSG_ALIGNTO
         * as 4, which older kernels do, or as 4U, which newer
         * kernels do.
         *
         * ep - bp is of type ptrdiff_t, which is signed.
         *
         * To squelch warnings, we cast both to size_t, which
         * is unsigned; ep >= bp, so the cast is safe.
         */
        if ((size_t)(ep - bp) < (size_t)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) {
            snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Message truncated: (got: %zd) (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) {
                    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 ||
                        pcap_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.
         *
         * To squelch warnings, we cast ep - bp to uint32_t, which
         * is unsigned and is the type of msg_len; ep >= bp, and
         * len should fit in 32 bits (either it's set from an int
         * or it's set from a recv() call with a buffer size that's
         * an int, and we're assuming either ILP32 or LP64), so
         * the cast is safe.
         */
        if (msg_len > (uint32_t)(ep - bp))
            msg_len = (uint32_t)(ep - bp);
 
        bp += msg_len;
        if (count >= max_packets && !PACKET_COUNT_IS_UNLIMITED(max_packets)) {
            handle->bp = bp;
            handle->cc = (int)(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_, int size _U_)
{
    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 {
            /*
             * The buffer is not so big that its size won't
             * fit into an int.
             */
            len = (int)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) {
                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) {
                    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) {
        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 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 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, 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;
}