/*
* dhcpcd - DHCP client daemon
* Copyright (c) 2006-2008 Roy Marples <[email protected]>
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/uio.h>

#include <net/bpf.h>
#include <net/if.h>
#include <arpa/inet.h>

#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "common.h"
#include "dhcp.h"
#include "net.h"
#include "bpf-filter.h"

#include <rump/rump.h>
#include <rump/rump_syscalls.h>

int
open_socket(struct interface *iface, int protocol)
{
       int fd = -1;
       int *fdp = NULL;
       struct ifreq ifr;
       int buf_len = 0;
       struct bpf_version pv;
       struct bpf_program pf;
#ifdef BIOCIMMEDIATE
       int flags;
#endif
#ifdef _PATH_BPF
       fd = rump_sys_open(_PATH_BPF, O_RDWR | O_NONBLOCK);
#else
       char *device;
       int n = 0;

       device = xmalloc(sizeof(char) * PATH_MAX);
       do {
               snprintf(device, PATH_MAX, "/dev/bpf%d", n++);
               fd = rump_sys_open(device, O_RDWR | O_NONBLOCK);
       } while (fd == -1 && errno == EBUSY);
       free(device);
#endif

       if (fd == -1)
               return -1;

       if (rump_sys_ioctl(fd, BIOCVERSION, &pv) == -1)
               goto eexit;
       if (pv.bv_major != BPF_MAJOR_VERSION ||
           pv.bv_minor < BPF_MINOR_VERSION) {
               fprintf(stderr, "BPF version mismatch - recompile");
               goto eexit;
       }

       memset(&ifr, 0, sizeof(ifr));
       strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
       if (rump_sys_ioctl(fd, BIOCSETIF, &ifr) == -1)
               goto eexit;

       /* Get the required BPF buffer length from the kernel. */
       if (rump_sys_ioctl(fd, BIOCGBLEN, &buf_len) == -1)
               goto eexit;
       if (iface->buffer_size != (size_t)buf_len) {
               free(iface->buffer);
               iface->buffer_size = buf_len;
               iface->buffer = xmalloc(buf_len);
               iface->buffer_len = iface->buffer_pos = 0;
       }

#ifdef BIOCIMMEDIATE
       flags = 1;
       if (rump_sys_ioctl(fd, BIOCIMMEDIATE, &flags) == -1)
               goto eexit;
#endif

       /* Install the DHCP filter */
       if (protocol == ETHERTYPE_ARP) {
               pf.bf_insns = UNCONST(arp_bpf_filter);
               pf.bf_len = arp_bpf_filter_len;
               fdp = &iface->arp_fd;
       } else {
               pf.bf_insns = UNCONST(dhcp_bpf_filter);
               pf.bf_len = dhcp_bpf_filter_len;
               fdp = &iface->raw_fd;
       }
       if (rump_sys_ioctl(fd, BIOCSETF, &pf) == -1)
               goto eexit;
       if (fdp) {
               if (*fdp != -1)
                       rump_sys_close(*fdp);
               *fdp = fd;
       }
       return fd;

eexit:
       free(iface->buffer);
       iface->buffer = NULL;
       rump_sys_close(fd);
       return -1;
}

ssize_t
send_raw_packet(const struct interface *iface, int protocol,
   const void *data, ssize_t len)
{
       struct iovec iov[2];
       struct ether_header hw;
       int fd;

       memset(&hw, 0, ETHER_HDR_LEN);
       memset(&hw.ether_dhost, 0xff, ETHER_ADDR_LEN);
       hw.ether_type = htons(protocol);
       iov[0].iov_base = &hw;
       iov[0].iov_len = ETHER_HDR_LEN;
       iov[1].iov_base = UNCONST(data);
       iov[1].iov_len = len;
       if (protocol == ETHERTYPE_ARP)
               fd = iface->arp_fd;
       else
               fd = iface->raw_fd;
       return rump_sys_writev(fd, iov, 2);
}

/* BPF requires that we read the entire buffer.
* So we pass the buffer in the API so we can loop on >1 packet. */
ssize_t
get_raw_packet(struct interface *iface, int protocol,
   void *data, ssize_t len)
{
       int fd = -1;
       struct bpf_hdr packet;
       ssize_t bytes;
       const unsigned char *payload;

       if (protocol == ETHERTYPE_ARP)
               fd = iface->arp_fd;
       else
               fd = iface->raw_fd;

       for (;;) {
               if (iface->buffer_len == 0) {
                       bytes = rump_sys_read(fd, iface->buffer, iface->buffer_size);
                       if (bytes == -1)
                               return errno == EAGAIN ? 0 : -1;
                       else if ((size_t)bytes < sizeof(packet))
                               return -1;
                       iface->buffer_len = bytes;
                       iface->buffer_pos = 0;
               }
               bytes = -1;
               memcpy(&packet, iface->buffer + iface->buffer_pos,
                   sizeof(packet));
               if (packet.bh_caplen != packet.bh_datalen)
                       goto next; /* Incomplete packet, drop. */
               if (iface->buffer_pos + packet.bh_caplen + packet.bh_hdrlen >
                   iface->buffer_len)
                       goto next; /* Packet beyond buffer, drop. */
               payload = iface->buffer + packet.bh_hdrlen + ETHER_HDR_LEN;
               bytes = packet.bh_caplen - ETHER_HDR_LEN;
               if (bytes > len)
                       bytes = len;
               memcpy(data, payload, bytes);
next:
               iface->buffer_pos += BPF_WORDALIGN(packet.bh_hdrlen +
                   packet.bh_caplen);
               if (iface->buffer_pos >= iface->buffer_len)
                       iface->buffer_len = iface->buffer_pos = 0;
               if (bytes != -1)
                       return bytes;
       }
}

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