/*
 * Copyright (c) 2014 Michal Labedzki for Tieto Corporation
 * 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.
 *
 */

#include <config.h>

#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>

#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>

#include "pcap/bluetooth.h"
#include "pcap-int.h"
#include "diag-control.h"

#include "pcap-bt-monitor-linux.h"

#define BT_CONTROL_SIZE 32
#define INTERFACE_NAME "bluetooth-monitor"

/*
 * Private data.
 * Currently contains nothing.
 */
struct pcap_bt_monitor {
	int	dummy;
};

/*
 * Fields and alignment must match the declaration in the Linux kernel 3.4+.
 * See struct hci_mon_hdr in include/net/bluetooth/hci_mon.h.
 */
struct hci_mon_hdr {
    uint16_t opcode;
    uint16_t index;
    uint16_t len;
} __attribute__((packed));

int
bt_monitor_findalldevs(pcap_if_list_t *devlistp, char *err_str)
{
    int         ret = 0;

    /*
     * Bluetooth is a wireless technology.
     *
     * This is a device to monitor all Bluetooth interfaces, so
     * there's no notion of "connected" or "disconnected", any
     * more than there's a notion of "connected" or "disconnected"
     * for the "any" device.
     */
    if (pcapint_add_dev(devlistp, INTERFACE_NAME,
                PCAP_IF_WIRELESS|PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE,
                "Bluetooth Linux Monitor", err_str) == NULL)
    {
        ret = PCAP_ERROR;
    }

    return ret;
}

static int
bt_monitor_read(pcap_t *handle, int max_packets _U_, pcap_handler callback, u_char *user)
{
    struct cmsghdr *cmsg;
    struct msghdr msg;
    struct iovec  iv[2];
    ssize_t ret;
    struct pcap_pkthdr pkth;
    pcap_bluetooth_linux_monitor_header *bthdr;
    u_char *pktd;
    struct hci_mon_hdr hdr;

    pktd = (u_char *)handle->buffer + BT_CONTROL_SIZE;
    bthdr = (pcap_bluetooth_linux_monitor_header*)(void *)pktd;

    iv[0].iov_base = &hdr;
    iv[0].iov_len = sizeof(hdr);
    iv[1].iov_base = pktd + sizeof(pcap_bluetooth_linux_monitor_header);
    iv[1].iov_len = handle->snapshot;

    memset(&pkth.ts, 0, sizeof(pkth.ts));
    memset(&msg, 0, sizeof(msg));
    msg.msg_iov = iv;
    msg.msg_iovlen = 2;
    msg.msg_control = handle->buffer;
    msg.msg_controllen = BT_CONTROL_SIZE;

    do {
        if (handle->break_loop)
        {
            handle->break_loop = 0;
            return PCAP_ERROR_BREAK;
        }
        ret = recvmsg(handle->fd, &msg, 0);
    } while ((ret == -1) && (errno == EINTR));

    if (ret < 0) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
            /* Nonblocking mode, no data */
            return 0;
        }
        pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
            errno, "Can't receive packet");
        return PCAP_ERROR;
    }

    pkth.caplen = (bpf_u_int32)(ret - sizeof(hdr) + sizeof(pcap_bluetooth_linux_monitor_header));
    pkth.len = pkth.caplen;

    // for musl libc CMSG_NXTHDR()
DIAG_OFF_SIGN_COMPARE
    for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
DIAG_ON_SIGN_COMPARE
        if (cmsg->cmsg_level != SOL_SOCKET) continue;

        if (cmsg->cmsg_type == SCM_TIMESTAMP) {
            memcpy(&pkth.ts, CMSG_DATA(cmsg), sizeof(pkth.ts));
        }
    }

    bthdr->adapter_id = htons(hdr.index);
    bthdr->opcode = htons(hdr.opcode);

    if (handle->fcode.bf_insns == NULL ||
        pcapint_filter(handle->fcode.bf_insns, pktd, pkth.len, pkth.caplen)) {
        callback(user, &pkth, pktd);
        return 1;
    }
    return 0;   /* didn't pass filter */
}

static int
bt_monitor_inject(pcap_t *handle, const void *buf _U_, int size _U_)
{
    snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
        "Packet injection is not supported yet on Bluetooth monitor devices");
    return PCAP_ERROR;
}

static int
bt_monitor_stats(pcap_t *handle _U_, struct pcap_stat *stats)
{
    stats->ps_recv = 0;
    stats->ps_drop = 0;
    stats->ps_ifdrop = 0;

    return 0;
}

static int
bt_monitor_activate(pcap_t* handle)
{
    struct sockaddr_hci addr;
    int err = PCAP_ERROR;
    int opt;

    if (handle->opt.rfmon) {
        /* monitor mode doesn't apply here */
        return PCAP_ERROR_RFMON_NOTSUP;
    }

    /*
     * 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;

    handle->bufsize = BT_CONTROL_SIZE + sizeof(pcap_bluetooth_linux_monitor_header) + handle->snapshot;
    handle->linktype = DLT_BLUETOOTH_LINUX_MONITOR;

    handle->read_op = bt_monitor_read;
    handle->inject_op = bt_monitor_inject;
    handle->setfilter_op = pcapint_install_bpf_program; /* no kernel filtering */
    handle->setdirection_op = NULL; /* Not implemented */
    handle->set_datalink_op = NULL; /* can't change data link type */
    handle->getnonblock_op = pcapint_getnonblock_fd;
    handle->setnonblock_op = pcapint_setnonblock_fd;
    handle->stats_op = bt_monitor_stats;

    handle->fd = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI);
    if (handle->fd < 0) {
        pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
            errno, "Can't create raw socket");
        return PCAP_ERROR;
    }

    handle->buffer = malloc(handle->bufsize);
    if (!handle->buffer) {
        pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
            errno, "Can't allocate dump buffer");
        goto close_fail;
    }

    /* Bind socket to the HCI device */
    addr.hci_family = AF_BLUETOOTH;
    addr.hci_dev = HCI_DEV_NONE;
    addr.hci_channel = HCI_CHANNEL_MONITOR;

    if (bind(handle->fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
        pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
            errno, "Can't attach to interface");
        goto close_fail;
    }

    opt = 1;
    if (setsockopt(handle->fd, SOL_SOCKET, SO_TIMESTAMP, &opt, sizeof(opt)) < 0) {
        pcapint_fmt_errmsg_for_errno(handle->errbuf, PCAP_ERRBUF_SIZE,
            errno, "Can't enable time stamp");
        goto close_fail;
    }

    handle->selectable_fd = handle->fd;

    return 0;

close_fail:
    pcapint_cleanup_live_common(handle);
    return err;
}

pcap_t *
bt_monitor_create(const char *device, char *ebuf, int *is_ours)
{
    pcap_t      *p;
    const char  *cp;

    cp = strrchr(device, '/');
    if (cp == NULL)
        cp = device;

    if (strcmp(cp, INTERFACE_NAME) != 0) {
        *is_ours = 0;
        return NULL;
    }

    *is_ours = 1;
    p = PCAP_CREATE_COMMON(ebuf, struct pcap_bt_monitor);
    if (p == NULL)
        return NULL;

    p->activate_op = bt_monitor_activate;

    return p;
}