FC

.gitignore

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+Makefile
+CMakeCache.txt
+CMakeFiles
+*.cmake
+install_manifest.txt
+relayd

CMakeLists.txt

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+cmake_minimum_required(VERSION 2.8)
+
+PROJECT(relayd C)
+ADD_DEFINITIONS(-Os -Wall -Werror --std=gnu99 -g3)
+
+IF(APPLE)
+  INCLUDE_DIRECTORIES(/opt/local/include)
+  LINK_DIRECTORIES(/opt/local/lib)
+ENDIF()
+
+ADD_EXECUTABLE(relayd main.c dhcp.c route.c)
+TARGET_LINK_LIBRARIES(relayd ubox)
+
+SET(CMAKE_INSTALL_PREFIX /usr)
+
+INSTALL(TARGETS relayd
+	RUNTIME DESTINATION sbin
+)

dhcp.c

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+/*
+ *   Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License v2 as published by
+ *   the Free Software Foundation.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#define _GNU_SOURCE
+#include <sys/socket.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "relayd.h"
+
+struct ip_packet {
+	struct ether_header eth;
+	struct iphdr iph;
+} __packed;
+
+
+enum {
+	DHCP_OPTION_ROUTER = 0x03,
+	DHCP_OPTION_ROUTES = 0x79,
+	DHCP_OPTION_END	= 0xff,
+};
+
+struct dhcp_option {
+	uint8_t code;
+	uint8_t len;
+	uint8_t data[];
+};
+
+struct dhcp_header {
+	uint8_t op, htype, hlen, hops;
+	uint32_t xit;
+	uint16_t secs, flags;
+	struct in_addr ciaddr, yiaddr, siaddr, giaddr;
+	unsigned char chaddr[16];
+	unsigned char sname[64];
+	unsigned char file[128];
+	uint32_t cookie;
+	uint8_t option_data[];
+} __packed;
+
+static uint16_t
+chksum(uint16_t sum, const uint8_t *data, uint16_t len)
+{
+	const uint8_t *last;
+	uint16_t t;
+
+	last = data + len - 1;
+
+	while(data < last) {
+		t = (data[0] << 8) + data[1];
+		sum += t;
+		if(sum < t)
+			sum++;
+		data += 2;
+	}
+
+	if(data == last) {
+		t = (data[0] << 8) + 0;
+		sum += t;
+		if(sum < t)
+			sum++;
+	}
+
+	return sum;
+}
+
+static void
+parse_dhcp_options(struct relayd_host *host, struct dhcp_header *dhcp, int len)
+{
+	uint8_t *end = (uint8_t *) dhcp + len;
+	struct dhcp_option *opt = (void *)dhcp->option_data;
+	static const uint8_t dest[4] = { 0, 0, 0, 0 };
+
+	while((uint8_t *) opt < end) {
+		if ((uint8_t *) opt + opt->len > end)
+			break;
+
+		opt = (void *) &opt->data[opt->len];
+		switch(opt->code) {
+		case DHCP_OPTION_ROUTER:
+			DPRINTF(2, "Found a DHCP router option, len=%d\n", opt->len);
+			if (!memcmp(opt->data, host->ipaddr, 4))
+				relayd_add_host_route(host, dest, 0);
+			else
+				relayd_add_pending_route(opt->data, dest, 0, 10000);
+			break;
+		case DHCP_OPTION_ROUTES:
+			DPRINTF(2, "Found a DHCP static routes option, len=%d\n", opt->len);
+			break;
+		case DHCP_OPTION_END:
+			opt = (void *) end;
+			continue;
+		default:
+			DPRINTF(3, "Skipping unknown DHCP option %02x\n", opt->code);
+			continue;
+		}
+
+	}
+}
+
+bool relayd_handle_dhcp_packet(struct relayd_interface *rif, void *data, int len, bool forward, bool parse)
+{
+	struct ip_packet *pkt = data;
+	struct udphdr *udp;
+	struct dhcp_header *dhcp;
+	struct relayd_host *host;
+	int udplen;
+	uint16_t sum;
+
+	if (pkt->eth.ether_type != htons(ETH_P_IP))
+		return false;
+
+	if (pkt->iph.version != 4)
+		return false;
+
+	if (pkt->iph.protocol != IPPROTO_UDP)
+		return false;
+
+	udp = (void *) ((char *) &pkt->iph + (pkt->iph.ihl << 2));
+	dhcp = (void *) (udp + 1);
+
+	udplen = ntohs(udp->len);
+	if (udplen > len - ((char *) udp - (char *) data))
+		return false;
+
+	if (udp->dest != htons(67) && udp->source != htons(67))
+		return false;
+
+	if (dhcp->op != 1 && dhcp->op != 2)
+		return false;
+
+	if (!forward)
+		return true;
+
+	if (dhcp->op == 2) {
+		host = relayd_refresh_host(rif, pkt->eth.ether_shost, (void *) &pkt->iph.saddr);
+		if (host && parse)
+			parse_dhcp_options(host, dhcp, udplen - sizeof(struct udphdr));
+	}
+
+	DPRINTF(2, "%s: handling DHCP %s\n", rif->ifname, (dhcp->op == 1 ? "request" : "response"));
+
+	dhcp->flags |= htons(DHCP_FLAG_BROADCAST);
+
+	udp->check = 0;
+	sum = udplen + IPPROTO_UDP;
+	sum = chksum(sum, (void *) &pkt->iph.saddr, 8);
+	sum = chksum(sum, (void *) udp, udplen);
+	if (sum == 0)
+		sum = 0xffff;
+
+	udp->check = htons(~sum);
+
+	relayd_forward_bcast_packet(rif, data, len);
+
+	return true;
+}
+
+