Split interface and socket out into OS bpf, if-bsd and if-linux.

1 files changed, 248 insertions, 0 deletions

diff --git a/bpf.c b/bpf.c
new file mode 100644
index 00000000..b6af76d4
--- /dev/null
+++ b/bpf.c
@@ -0,0 +1,248 @@
+/*
+ * dhcpcd - DHCP client daemon
+ * Copyright 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/param.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+
+#include <net/bpf.h>
+#include <net/if.h>
+#include <netinet/in_systm.h>
+#include <netinet/in.h>
+#include <netinet/udp.h>
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "config.h"
+#include "dhcp.h"
+#include "interface.h"
+#include "logger.h"
+#include "socket.h"
+
+void
+setup_packet_filters(void)
+{
+	/* Empty function */
+}
+
+int
+open_socket(struct interface *iface, int protocol)
+{
+	int n = 0;
+	int fd = -1;
+	char *device;
+	int flags;
+	struct ifreq ifr;
+	int buf = 0;
+	struct bpf_program pf;
+
+	device = xmalloc(sizeof(char) * PATH_MAX);
+	do {
+		snprintf(device, PATH_MAX, "/dev/bpf%d",  n++);
+		fd = open(device, O_RDWR);
+	} while (fd == -1 && errno == EBUSY);
+	free(device);
+
+	if (fd == -1) {
+		logger(LOG_ERR, "unable to open a BPF device");
+		return -1;
+	}
+
+	close_on_exec(fd);
+
+	memset(&ifr, 0, sizeof(ifr));
+	strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
+	if (ioctl(fd, BIOCSETIF, &ifr) == -1) {
+		logger(LOG_ERR,
+		       "cannot attach interface `%s' to bpf device `%s': %s",
+		       iface->name, device, strerror(errno));
+		close(fd);
+		return -1;
+	}
+
+	/* Get the required BPF buffer length from the kernel. */
+	if (ioctl(fd, BIOCGBLEN, &buf) == -1) {
+		logger (LOG_ERR, "ioctl BIOCGBLEN: %s", strerror(errno));
+		close(fd);
+		return -1;
+	}
+	iface->buffer_length = buf;
+
+	flags = 1;
+	if (ioctl(fd, BIOCIMMEDIATE, &flags) == -1) {
+		logger(LOG_ERR, "ioctl BIOCIMMEDIATE: %s", strerror(errno));
+		close(fd);
+		return -1;
+	}
+
+	/* Install the DHCP filter */
+	if (protocol == ETHERTYPE_ARP) {
+		pf.bf_insns = arp_bpf_filter;
+		pf.bf_len = sizeof(arp_bpf_filter) / sizeof(arp_bpf_filter[0]);
+	} else {
+		pf.bf_insns = dhcp_bpf_filter;
+		pf.bf_len = sizeof(dhcp_bpf_filter)/sizeof(dhcp_bpf_filter[0]);
+	}
+	if (ioctl(fd, BIOCSETF, &pf) == -1) {
+		logger(LOG_ERR, "ioctl BIOCSETF: %s", strerror(errno));
+		close(fd);
+		return -1;
+	}
+
+	if (iface->fd > -1)
+		close(iface->fd);
+	iface->fd = fd;
+
+	return fd;
+}
+
+ssize_t
+send_packet(const struct interface *iface, int type,
+	    const unsigned char *data, size_t len)
+{
+	ssize_t retval = -1;
+	struct iovec iov[2];
+	struct ether_header hw;
+
+	if (iface->family == ARPHRD_ETHER) {
+		memset(&hw, 0, sizeof(hw));
+		memset(&hw.ether_dhost, 0xff, ETHER_ADDR_LEN);
+		hw.ether_type = htons(type);
+
+		iov[0].iov_base = &hw;
+		iov[0].iov_len = sizeof(hw);
+	} else {
+		logger(LOG_ERR, "unsupported interace type %d", iface->family);
+		return -1;
+	}
+	iov[1].iov_base = (unsigned char *)data;
+	iov[1].iov_len = len;
+
+	if ((retval = writev(iface->fd, iov, 2)) == -1)
+		logger(LOG_ERR, "writev: %s", strerror(errno));
+
+	return retval;
+}
+
+/* BPF requires that we read the entire buffer.
+ * So we pass the buffer in the API so we can loop on >1 dhcp packet. */
+ssize_t
+get_packet(const struct interface *iface, unsigned char *data,
+	   unsigned char *buffer, size_t *buffer_len, size_t *buffer_pos)
+{
+	union
+	{
+		unsigned char *buffer;
+		struct bpf_hdr *packet;
+	} bpf;
+	union
+	{
+		unsigned char *buffer;
+		struct ether_header *hw;
+	} hdr;
+	union
+	{
+		unsigned char *buffer;
+		struct udp_dhcp_packet *packet;
+	} pay;
+	struct timespec ts;
+	size_t len;
+	unsigned char *payload;
+	bool have_data;
+
+	bpf.buffer = buffer;
+
+	if (*buffer_pos < 1) {
+		memset(bpf.buffer, 0, iface->buffer_length);
+		*buffer_len = read(iface->fd, bpf.buffer, iface->buffer_length);
+		*buffer_pos = 0;
+		if (*buffer_len < 1) {
+			logger(LOG_ERR, "read: %s", strerror(errno));
+			ts.tv_sec = 3;
+			ts.tv_nsec = 0;
+			nanosleep(&ts, NULL);
+			return -1;
+		}
+	} else
+		bpf.buffer += *buffer_pos;
+
+	while (bpf.packet) {
+		len = 0;
+		have_data = false;
+
+		/* Ensure that the entire packet is in our buffer */
+		if (*buffer_pos +
+		    bpf.packet->bh_hdrlen +
+		    bpf.packet->bh_caplen > (unsigned)*buffer_len)
+			break;
+
+		hdr.buffer = bpf.buffer + bpf.packet->bh_hdrlen;
+		payload = hdr.buffer + sizeof(*hdr.hw);
+
+		/* If it's an ARP reply, then just send it back */
+		if (hdr.hw->ether_type == htons (ETHERTYPE_ARP)) {
+			len = bpf.packet->bh_caplen - sizeof(*hdr.hw);
+			memcpy(data, payload, len);
+			have_data = true;
+		} else {
+			if (valid_dhcp_packet(payload) >= 0) {
+				pay.buffer = payload;
+				len = ntohs(pay.packet->ip.ip_len) -
+					sizeof(pay.packet->ip) -
+					sizeof(pay.packet->udp);
+				memcpy(data, &pay.packet->dhcp, len);
+				have_data = true;
+			}
+		}
+
+		/* Update the buffer_pos pointer */
+		bpf.buffer += BPF_WORDALIGN(bpf.packet->bh_hdrlen +
+					    bpf.packet->bh_caplen);
+		if ((unsigned)(bpf.buffer - buffer) < *buffer_len)
+			*buffer_pos = bpf.buffer - buffer;
+		else
+			*buffer_pos = 0;
+
+		if (have_data)
+			return len;
+
+		if (*buffer_pos == 0)
+			break;
+	}
+
+	/* No valid packets left, so return */
+	*buffer_pos = 0;
+	return -1;
+}