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* dhcpcd - DHCP client daemon
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* Copyright (c) 2006-2013 Roy Marples <roy@marples.name>
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <arpa/inet.h>
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#include "bpf-filter.h"
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ipv4_opensocket(struct interface *ifp, int protocol)
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struct dhcp_state *state;
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struct bpf_version pv;
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struct bpf_program pf;
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fd = open(_PATH_BPF, O_RDWR | O_NONBLOCK);
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device = malloc(sizeof(char) * PATH_MAX);
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snprintf(device, PATH_MAX, "/dev/bpf%d", n++);
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fd = open(device, O_RDWR | O_NONBLOCK);
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} while (fd == -1 && errno == EBUSY);
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if (ioctl(fd, BIOCVERSION, &pv) == -1)
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if (pv.bv_major != BPF_MAJOR_VERSION ||
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pv.bv_minor < BPF_MINOR_VERSION) {
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syslog(LOG_ERR, "BPF version mismatch - recompile");
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memset(&ifr, 0, sizeof(ifr));
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strlcpy(ifr.ifr_name, ifp->name, sizeof(ifr.ifr_name));
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if (ioctl(fd, BIOCSETIF, &ifr) == -1)
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/* Get the required BPF buffer length from the kernel. */
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if (ioctl(fd, BIOCGBLEN, &buf_len) == -1)
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if (state->buffer_size != (size_t)buf_len) {
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state->buffer = malloc(buf_len);
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if (state->buffer == NULL)
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state->buffer_size = buf_len;
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state->buffer_len = state->buffer_pos = 0;
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if (ioctl(fd, BIOCIMMEDIATE, &flags) == -1)
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/* Install the DHCP filter */
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if (protocol == ETHERTYPE_ARP) {
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pf.bf_insns = UNCONST(arp_bpf_filter);
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pf.bf_len = arp_bpf_filter_len;
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fdp = &state->arp_fd;
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pf.bf_insns = UNCONST(dhcp_bpf_filter);
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pf.bf_len = dhcp_bpf_filter_len;
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fdp = &state->raw_fd;
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if (ioctl(fd, BIOCSETF, &pf) == -1)
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if (set_cloexec(fd) == -1)
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state->buffer = NULL;
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ipv4_sendrawpacket(const struct interface *ifp, int protocol,
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const void *data, ssize_t len)
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struct ether_header hw;
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const struct dhcp_state *state;
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memset(&hw, 0, ETHER_HDR_LEN);
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memset(&hw.ether_dhost, 0xff, ETHER_ADDR_LEN);
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hw.ether_type = htons(protocol);
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iov[0].iov_base = &hw;
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iov[0].iov_len = ETHER_HDR_LEN;
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iov[1].iov_base = UNCONST(data);
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iov[1].iov_len = len;
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state = D_CSTATE(ifp);
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if (protocol == ETHERTYPE_ARP)
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return writev(fd, iov, 2);
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/* BPF requires that we read the entire buffer.
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* So we pass the buffer in the API so we can loop on >1 packet. */
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ipv4_getrawpacket(struct interface *ifp, int protocol,
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void *data, ssize_t len, int *partialcsum)
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struct bpf_hdr packet;
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const unsigned char *payload;
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struct dhcp_state *state;
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state = D_STATE(ifp);
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if (protocol == ETHERTYPE_ARP)
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if (partialcsum != NULL)
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*partialcsum = 0; /* Not supported on BSD */
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if (state->buffer_len == 0) {
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bytes = read(fd, state->buffer, state->buffer_size);
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return errno == EAGAIN ? 0 : -1;
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else if ((size_t)bytes < sizeof(packet))
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state->buffer_len = bytes;
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state->buffer_pos = 0;
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memcpy(&packet, state->buffer + state->buffer_pos,
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if (packet.bh_caplen != packet.bh_datalen)
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goto next; /* Incomplete packet, drop. */
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if (state->buffer_pos + packet.bh_caplen + packet.bh_hdrlen >
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goto next; /* Packet beyond buffer, drop. */
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payload = state->buffer + packet.bh_hdrlen + ETHER_HDR_LEN;
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bytes = packet.bh_caplen - ETHER_HDR_LEN;
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memcpy(data, payload, bytes);
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state->buffer_pos += BPF_WORDALIGN(packet.bh_hdrlen +
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if (state->buffer_pos >= state->buffer_len)
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state->buffer_len = state->buffer_pos = 0;
added
removed
bpf.c
