240 lines
6.7 KiB
C
240 lines
6.7 KiB
C
/*
|
|
* Copyright 2008, The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <sys/uio.h>
|
|
#include <sys/socket.h>
|
|
#include <netinet/in.h>
|
|
#include <netinet/ip.h>
|
|
#include <netinet/udp.h>
|
|
#include <linux/if_packet.h>
|
|
#include <linux/if_ether.h>
|
|
#include <errno.h>
|
|
|
|
#ifdef ANDROID
|
|
#define LOG_TAG "DHCP"
|
|
#include <cutils/log.h>
|
|
#else
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#define LOGD printf
|
|
#define LOGW printf
|
|
#endif
|
|
|
|
#include "dhcpmsg.h"
|
|
|
|
int fatal();
|
|
|
|
int open_raw_socket(const char *ifname, uint8_t *hwaddr, int if_index)
|
|
{
|
|
int s, flag;
|
|
struct sockaddr_ll bindaddr;
|
|
|
|
if((s = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) {
|
|
return fatal("socket(PF_PACKET)");
|
|
}
|
|
|
|
memset(&bindaddr, 0, sizeof(bindaddr));
|
|
bindaddr.sll_family = AF_PACKET;
|
|
bindaddr.sll_protocol = htons(ETH_P_IP);
|
|
bindaddr.sll_halen = ETH_ALEN;
|
|
memcpy(bindaddr.sll_addr, hwaddr, ETH_ALEN);
|
|
bindaddr.sll_ifindex = if_index;
|
|
|
|
if (bind(s, (struct sockaddr *)&bindaddr, sizeof(bindaddr)) < 0) {
|
|
return fatal("Cannot bind raw socket to interface");
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
static uint32_t checksum(void *buffer, unsigned int count, uint32_t startsum)
|
|
{
|
|
uint16_t *up = (uint16_t *)buffer;
|
|
uint32_t sum = startsum;
|
|
uint32_t upper16;
|
|
|
|
while (count > 1) {
|
|
sum += *up++;
|
|
count -= 2;
|
|
}
|
|
if (count > 0) {
|
|
sum += (uint16_t) *(uint8_t *)up;
|
|
}
|
|
while ((upper16 = (sum >> 16)) != 0) {
|
|
sum = (sum & 0xffff) + upper16;
|
|
}
|
|
return sum;
|
|
}
|
|
|
|
static uint32_t finish_sum(uint32_t sum)
|
|
{
|
|
return ~sum & 0xffff;
|
|
}
|
|
|
|
int send_packet(int s, int if_index, struct dhcp_msg *msg, int size,
|
|
uint32_t saddr, uint32_t daddr, uint32_t sport, uint32_t dport)
|
|
{
|
|
struct iphdr ip;
|
|
struct udphdr udp;
|
|
struct iovec iov[3];
|
|
uint32_t udpsum;
|
|
uint16_t temp;
|
|
struct msghdr msghdr;
|
|
struct sockaddr_ll destaddr;
|
|
|
|
ip.version = IPVERSION;
|
|
ip.ihl = sizeof(ip) >> 2;
|
|
ip.tos = 0;
|
|
ip.tot_len = htons(sizeof(ip) + sizeof(udp) + size);
|
|
ip.id = 0;
|
|
ip.frag_off = 0;
|
|
ip.ttl = IPDEFTTL;
|
|
ip.protocol = IPPROTO_UDP;
|
|
ip.check = 0;
|
|
ip.saddr = saddr;
|
|
ip.daddr = daddr;
|
|
ip.check = finish_sum(checksum(&ip, sizeof(ip), 0));
|
|
|
|
udp.source = htons(sport);
|
|
udp.dest = htons(dport);
|
|
udp.len = htons(sizeof(udp) + size);
|
|
udp.check = 0;
|
|
|
|
/* Calculate checksum for pseudo header */
|
|
udpsum = checksum(&ip.saddr, sizeof(ip.saddr), 0);
|
|
udpsum = checksum(&ip.daddr, sizeof(ip.daddr), udpsum);
|
|
temp = htons(IPPROTO_UDP);
|
|
udpsum = checksum(&temp, sizeof(temp), udpsum);
|
|
temp = udp.len;
|
|
udpsum = checksum(&temp, sizeof(temp), udpsum);
|
|
|
|
/* Add in the checksum for the udp header */
|
|
udpsum = checksum(&udp, sizeof(udp), udpsum);
|
|
|
|
/* Add in the checksum for the data */
|
|
udpsum = checksum(msg, size, udpsum);
|
|
udp.check = finish_sum(udpsum);
|
|
|
|
iov[0].iov_base = (char *)&ip;
|
|
iov[0].iov_len = sizeof(ip);
|
|
iov[1].iov_base = (char *)&udp;
|
|
iov[1].iov_len = sizeof(udp);
|
|
iov[2].iov_base = (char *)msg;
|
|
iov[2].iov_len = size;
|
|
memset(&destaddr, 0, sizeof(destaddr));
|
|
destaddr.sll_family = AF_PACKET;
|
|
destaddr.sll_protocol = htons(ETH_P_IP);
|
|
destaddr.sll_ifindex = if_index;
|
|
destaddr.sll_halen = ETH_ALEN;
|
|
memcpy(destaddr.sll_addr, "\xff\xff\xff\xff\xff\xff", ETH_ALEN);
|
|
|
|
msghdr.msg_name = &destaddr;
|
|
msghdr.msg_namelen = sizeof(destaddr);
|
|
msghdr.msg_iov = iov;
|
|
msghdr.msg_iovlen = sizeof(iov) / sizeof(struct iovec);
|
|
msghdr.msg_flags = 0;
|
|
msghdr.msg_control = 0;
|
|
msghdr.msg_controllen = 0;
|
|
return sendmsg(s, &msghdr, 0);
|
|
}
|
|
|
|
int receive_packet(int s, struct dhcp_msg *msg)
|
|
{
|
|
int nread;
|
|
int is_valid;
|
|
struct dhcp_packet {
|
|
struct iphdr ip;
|
|
struct udphdr udp;
|
|
struct dhcp_msg dhcp;
|
|
} packet;
|
|
int dhcp_size;
|
|
uint32_t sum;
|
|
uint16_t temp;
|
|
uint32_t saddr, daddr;
|
|
|
|
nread = read(s, &packet, sizeof(packet));
|
|
if (nread < 0) {
|
|
return -1;
|
|
}
|
|
/*
|
|
* The raw packet interface gives us all packets received by the
|
|
* network interface. We need to filter out all packets that are
|
|
* not meant for us.
|
|
*/
|
|
is_valid = 0;
|
|
if (nread < (int)(sizeof(struct iphdr) + sizeof(struct udphdr))) {
|
|
#if VERBOSE
|
|
LOGD("Packet is too small (%d) to be a UDP datagram", nread);
|
|
#endif
|
|
} else if (packet.ip.version != IPVERSION || packet.ip.ihl != (sizeof(packet.ip) >> 2)) {
|
|
#if VERBOSE
|
|
LOGD("Not a valid IP packet");
|
|
#endif
|
|
} else if (nread < ntohs(packet.ip.tot_len)) {
|
|
#if VERBOSE
|
|
LOGD("Packet was truncated (read %d, needed %d)", nread, ntohs(packet.ip.tot_len));
|
|
#endif
|
|
} else if (packet.ip.protocol != IPPROTO_UDP) {
|
|
#if VERBOSE
|
|
LOGD("IP protocol (%d) is not UDP", packet.ip.protocol);
|
|
#endif
|
|
} else if (packet.udp.dest != htons(PORT_BOOTP_CLIENT)) {
|
|
#if VERBOSE
|
|
LOGD("UDP dest port (%d) is not DHCP client", ntohs(packet.udp.dest));
|
|
#endif
|
|
} else {
|
|
is_valid = 1;
|
|
}
|
|
|
|
if (!is_valid) {
|
|
return -1;
|
|
}
|
|
|
|
/* Seems like it's probably a valid DHCP packet */
|
|
/* validate IP header checksum */
|
|
sum = finish_sum(checksum(&packet.ip, sizeof(packet.ip), 0));
|
|
if (sum != 0) {
|
|
LOGW("IP header checksum failure (0x%x)", packet.ip.check);
|
|
return -1;
|
|
}
|
|
/*
|
|
* Validate the UDP checksum.
|
|
* Since we don't need the IP header anymore, we "borrow" it
|
|
* to construct the pseudo header used in the checksum calculation.
|
|
*/
|
|
dhcp_size = ntohs(packet.udp.len) - sizeof(packet.udp);
|
|
saddr = packet.ip.saddr;
|
|
daddr = packet.ip.daddr;
|
|
nread = ntohs(packet.ip.tot_len);
|
|
memset(&packet.ip, 0, sizeof(packet.ip));
|
|
packet.ip.saddr = saddr;
|
|
packet.ip.daddr = daddr;
|
|
packet.ip.protocol = IPPROTO_UDP;
|
|
packet.ip.tot_len = packet.udp.len;
|
|
temp = packet.udp.check;
|
|
packet.udp.check = 0;
|
|
sum = finish_sum(checksum(&packet, nread, 0));
|
|
packet.udp.check = temp;
|
|
if (temp != sum) {
|
|
LOGW("UDP header checksum failure (0x%x should be 0x%x)", sum, temp);
|
|
return -1;
|
|
}
|
|
memcpy(msg, &packet.dhcp, dhcp_size);
|
|
return dhcp_size;
|
|
}
|