| /* |
| * dhcpcd - DHCP client daemon |
| * Copyright (c) 2006-2008 Roy Marples <roy@marples.name> |
| * |
| * 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 <syslog.h> |
| #include <unistd.h> |
| |
| #include "config.h" |
| #include "common.h" |
| #include "dhcp.h" |
| #include "net.h" |
| #include "bpf-filter.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 = 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 = open(device, O_RDWR | O_NONBLOCK); |
| } while (fd == -1 && errno == EBUSY); |
| free(device); |
| #endif |
| |
| if (fd == -1) |
| return -1; |
| |
| if (ioctl(fd, BIOCVERSION, &pv) == -1) |
| goto eexit; |
| if (pv.bv_major != BPF_MAJOR_VERSION || |
| pv.bv_minor < BPF_MINOR_VERSION) { |
| syslog(LOG_ERR, "BPF version mismatch - recompile"); |
| goto eexit; |
| } |
| |
| memset(&ifr, 0, sizeof(ifr)); |
| strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name)); |
| if (ioctl(fd, BIOCSETIF, &ifr) == -1) |
| goto eexit; |
| |
| /* Get the required BPF buffer length from the kernel. */ |
| if (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 (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 (ioctl(fd, BIOCSETF, &pf) == -1) |
| goto eexit; |
| if (set_cloexec(fd) == -1) |
| goto eexit; |
| if (fdp) { |
| if (*fdp != -1) |
| close(*fdp); |
| *fdp = fd; |
| } |
| return fd; |
| |
| eexit: |
| free(iface->buffer); |
| iface->buffer = NULL; |
| close(fd); |
| return -1; |
| } |
| |
| ssize_t |
| send_raw_packet(const struct interface *iface, int protocol, |
| const void *data, ssize_t len, const uint8_t *dest_hw_addr) |
| { |
| struct iovec iov[2]; |
| struct ether_header hw; |
| int fd; |
| |
| memset(&hw, 0, ETHER_HDR_LEN); |
| if (dest_hw_addr != NULL) |
| memcpy(&hw.ether_dhost, dest_hw_addr, ETHER_ADDR_LEN); |
| else |
| 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 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 = 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; |
| } |
| } |