The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 1 | /* |
| 2 | * dhcpcd - DHCP client daemon |
Dmitry Shmidt | a3a2260 | 2012-07-23 16:45:46 -0700 | [diff] [blame] | 3 | * Copyright (c) 2006-2011 Roy Marples <roy@marples.name> |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
| 13 | * |
| 14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| 15 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 16 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 17 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 18 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 19 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 20 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 21 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 22 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 23 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 24 | * SUCH DAMAGE. |
| 25 | */ |
| 26 | |
| 27 | #include <sys/types.h> |
| 28 | #include <sys/ioctl.h> |
| 29 | #include <sys/socket.h> |
| 30 | #include <sys/uio.h> |
| 31 | |
| 32 | #include <net/bpf.h> |
| 33 | #include <net/if.h> |
| 34 | #include <arpa/inet.h> |
| 35 | |
| 36 | #include <errno.h> |
| 37 | #include <fcntl.h> |
| 38 | #include <paths.h> |
| 39 | #include <stdio.h> |
| 40 | #include <stdlib.h> |
| 41 | #include <string.h> |
Dmitry Shmidt | e86eee1 | 2011-01-24 16:27:51 -0800 | [diff] [blame] | 42 | #include <syslog.h> |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 43 | #include <unistd.h> |
| 44 | |
| 45 | #include "config.h" |
| 46 | #include "common.h" |
| 47 | #include "dhcp.h" |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 48 | #include "net.h" |
| 49 | #include "bpf-filter.h" |
| 50 | |
| 51 | int |
| 52 | open_socket(struct interface *iface, int protocol) |
| 53 | { |
| 54 | int fd = -1; |
| 55 | int *fdp = NULL; |
| 56 | struct ifreq ifr; |
| 57 | int buf_len = 0; |
| 58 | struct bpf_version pv; |
| 59 | struct bpf_program pf; |
| 60 | #ifdef BIOCIMMEDIATE |
| 61 | int flags; |
| 62 | #endif |
| 63 | #ifdef _PATH_BPF |
| 64 | fd = open(_PATH_BPF, O_RDWR | O_NONBLOCK); |
| 65 | #else |
| 66 | char *device; |
| 67 | int n = 0; |
| 68 | |
| 69 | device = xmalloc(sizeof(char) * PATH_MAX); |
| 70 | do { |
| 71 | snprintf(device, PATH_MAX, "/dev/bpf%d", n++); |
| 72 | fd = open(device, O_RDWR | O_NONBLOCK); |
| 73 | } while (fd == -1 && errno == EBUSY); |
| 74 | free(device); |
| 75 | #endif |
| 76 | |
| 77 | if (fd == -1) |
| 78 | return -1; |
| 79 | |
| 80 | if (ioctl(fd, BIOCVERSION, &pv) == -1) |
| 81 | goto eexit; |
| 82 | if (pv.bv_major != BPF_MAJOR_VERSION || |
| 83 | pv.bv_minor < BPF_MINOR_VERSION) { |
Dmitry Shmidt | e86eee1 | 2011-01-24 16:27:51 -0800 | [diff] [blame] | 84 | syslog(LOG_ERR, "BPF version mismatch - recompile"); |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 85 | goto eexit; |
| 86 | } |
| 87 | |
| 88 | memset(&ifr, 0, sizeof(ifr)); |
| 89 | strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name)); |
| 90 | if (ioctl(fd, BIOCSETIF, &ifr) == -1) |
| 91 | goto eexit; |
| 92 | |
| 93 | /* Get the required BPF buffer length from the kernel. */ |
| 94 | if (ioctl(fd, BIOCGBLEN, &buf_len) == -1) |
| 95 | goto eexit; |
| 96 | if (iface->buffer_size != (size_t)buf_len) { |
| 97 | free(iface->buffer); |
| 98 | iface->buffer_size = buf_len; |
| 99 | iface->buffer = xmalloc(buf_len); |
| 100 | iface->buffer_len = iface->buffer_pos = 0; |
| 101 | } |
| 102 | |
| 103 | #ifdef BIOCIMMEDIATE |
| 104 | flags = 1; |
| 105 | if (ioctl(fd, BIOCIMMEDIATE, &flags) == -1) |
| 106 | goto eexit; |
| 107 | #endif |
| 108 | |
| 109 | /* Install the DHCP filter */ |
| 110 | if (protocol == ETHERTYPE_ARP) { |
| 111 | pf.bf_insns = UNCONST(arp_bpf_filter); |
| 112 | pf.bf_len = arp_bpf_filter_len; |
| 113 | fdp = &iface->arp_fd; |
| 114 | } else { |
| 115 | pf.bf_insns = UNCONST(dhcp_bpf_filter); |
| 116 | pf.bf_len = dhcp_bpf_filter_len; |
| 117 | fdp = &iface->raw_fd; |
| 118 | } |
| 119 | if (ioctl(fd, BIOCSETF, &pf) == -1) |
| 120 | goto eexit; |
| 121 | if (set_cloexec(fd) == -1) |
| 122 | goto eexit; |
| 123 | if (fdp) { |
| 124 | if (*fdp != -1) |
| 125 | close(*fdp); |
| 126 | *fdp = fd; |
| 127 | } |
| 128 | return fd; |
| 129 | |
| 130 | eexit: |
| 131 | free(iface->buffer); |
| 132 | iface->buffer = NULL; |
| 133 | close(fd); |
| 134 | return -1; |
| 135 | } |
| 136 | |
| 137 | ssize_t |
| 138 | send_raw_packet(const struct interface *iface, int protocol, |
Dmitry Shmidt | e86eee1 | 2011-01-24 16:27:51 -0800 | [diff] [blame] | 139 | const void *data, ssize_t len) |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 140 | { |
| 141 | struct iovec iov[2]; |
| 142 | struct ether_header hw; |
| 143 | int fd; |
| 144 | |
| 145 | memset(&hw, 0, ETHER_HDR_LEN); |
| 146 | memset(&hw.ether_dhost, 0xff, ETHER_ADDR_LEN); |
| 147 | hw.ether_type = htons(protocol); |
| 148 | iov[0].iov_base = &hw; |
| 149 | iov[0].iov_len = ETHER_HDR_LEN; |
| 150 | iov[1].iov_base = UNCONST(data); |
| 151 | iov[1].iov_len = len; |
| 152 | if (protocol == ETHERTYPE_ARP) |
| 153 | fd = iface->arp_fd; |
| 154 | else |
| 155 | fd = iface->raw_fd; |
| 156 | return writev(fd, iov, 2); |
| 157 | } |
| 158 | |
| 159 | /* BPF requires that we read the entire buffer. |
| 160 | * So we pass the buffer in the API so we can loop on >1 packet. */ |
| 161 | ssize_t |
| 162 | get_raw_packet(struct interface *iface, int protocol, |
Dmitry Shmidt | a3a2260 | 2012-07-23 16:45:46 -0700 | [diff] [blame] | 163 | void *data, ssize_t len, int *partialcsum) |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 164 | { |
| 165 | int fd = -1; |
| 166 | struct bpf_hdr packet; |
| 167 | ssize_t bytes; |
| 168 | const unsigned char *payload; |
| 169 | |
| 170 | if (protocol == ETHERTYPE_ARP) |
| 171 | fd = iface->arp_fd; |
| 172 | else |
| 173 | fd = iface->raw_fd; |
| 174 | |
Dmitry Shmidt | a3a2260 | 2012-07-23 16:45:46 -0700 | [diff] [blame] | 175 | if (partialcsum != NULL) |
| 176 | *partialcsum = 0; /* Not supported on BSD */ |
| 177 | |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 178 | for (;;) { |
| 179 | if (iface->buffer_len == 0) { |
| 180 | bytes = read(fd, iface->buffer, iface->buffer_size); |
| 181 | if (bytes == -1) |
| 182 | return errno == EAGAIN ? 0 : -1; |
| 183 | else if ((size_t)bytes < sizeof(packet)) |
| 184 | return -1; |
| 185 | iface->buffer_len = bytes; |
| 186 | iface->buffer_pos = 0; |
| 187 | } |
| 188 | bytes = -1; |
| 189 | memcpy(&packet, iface->buffer + iface->buffer_pos, |
Dmitry Shmidt | e86eee1 | 2011-01-24 16:27:51 -0800 | [diff] [blame] | 190 | sizeof(packet)); |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 191 | if (packet.bh_caplen != packet.bh_datalen) |
| 192 | goto next; /* Incomplete packet, drop. */ |
| 193 | if (iface->buffer_pos + packet.bh_caplen + packet.bh_hdrlen > |
| 194 | iface->buffer_len) |
| 195 | goto next; /* Packet beyond buffer, drop. */ |
| 196 | payload = iface->buffer + packet.bh_hdrlen + ETHER_HDR_LEN; |
| 197 | bytes = packet.bh_caplen - ETHER_HDR_LEN; |
| 198 | if (bytes > len) |
| 199 | bytes = len; |
| 200 | memcpy(data, payload, bytes); |
| 201 | next: |
| 202 | iface->buffer_pos += BPF_WORDALIGN(packet.bh_hdrlen + |
Dmitry Shmidt | e86eee1 | 2011-01-24 16:27:51 -0800 | [diff] [blame] | 203 | packet.bh_caplen); |
The Android Open Source Project | f7c5421 | 2009-03-03 19:29:22 -0800 | [diff] [blame] | 204 | if (iface->buffer_pos >= iface->buffer_len) |
| 205 | iface->buffer_len = iface->buffer_pos = 0; |
| 206 | if (bytes != -1) |
| 207 | return bytes; |
| 208 | } |
| 209 | } |