/*      $NetBSD: pcap-bt-monitor-linux.c,v 1.8 2024/09/02 15:33:37 christos Exp $       */

/*
* 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 <sys/cdefs.h>
__RCSID("$NetBSD: pcap-bt-monitor-linux.c,v 1.8 2024/09/02 15:33:37 christos Exp $");

#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;
}

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