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platform_system_core/libnetutils/dhcpclient.c

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/*
* 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.
*/
#define LOG_TAG "DHCP"
#include <dirent.h>
#include <errno.h>
#include <poll.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include <android/log.h>
#include <cutils/properties.h>
#include <netutils/ifc.h>
#include "dhcpmsg.h"
#include "packet.h"
#define VERBOSE 2
static int verbose = 1;
static char errmsg[2048];
typedef unsigned long long msecs_t;
#if VERBOSE
void dump_dhcp_msg();
#endif
msecs_t get_msecs(void)
{
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts)) {
return 0;
} else {
return (((msecs_t) ts.tv_sec) * ((msecs_t) 1000)) +
(((msecs_t) ts.tv_nsec) / ((msecs_t) 1000000));
}
}
void printerr(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vsnprintf(errmsg, sizeof(errmsg), fmt, ap);
va_end(ap);
ALOGD("%s", errmsg);
}
const char *dhcp_lasterror()
{
return errmsg;
}
int fatal(const char *reason)
{
printerr("%s: %s\n", reason, strerror(errno));
return -1;
// exit(1);
}
const char *ipaddr(in_addr_t addr)
{
struct in_addr in_addr;
in_addr.s_addr = addr;
return inet_ntoa(in_addr);
}
extern int ipv4NetmaskToPrefixLength(in_addr_t mask);
typedef struct dhcp_info dhcp_info;
struct dhcp_info {
uint32_t type;
uint32_t ipaddr;
uint32_t gateway;
uint32_t prefixLength;
uint32_t dns1;
uint32_t dns2;
uint32_t serveraddr;
uint32_t lease;
};
dhcp_info last_good_info;
void get_dhcp_info(uint32_t *ipaddr, uint32_t *gateway, uint32_t *prefixLength,
uint32_t *dns1, uint32_t *dns2, uint32_t *server,
uint32_t *lease)
{
*ipaddr = last_good_info.ipaddr;
*gateway = last_good_info.gateway;
*prefixLength = last_good_info.prefixLength;
*dns1 = last_good_info.dns1;
*dns2 = last_good_info.dns2;
*server = last_good_info.serveraddr;
*lease = last_good_info.lease;
}
static int dhcp_configure(const char *ifname, dhcp_info *info)
{
last_good_info = *info;
return ifc_configure(ifname, info->ipaddr, info->prefixLength, info->gateway,
info->dns1, info->dns2);
}
static const char *dhcp_type_to_name(uint32_t type)
{
switch(type) {
case DHCPDISCOVER: return "discover";
case DHCPOFFER: return "offer";
case DHCPREQUEST: return "request";
case DHCPDECLINE: return "decline";
case DHCPACK: return "ack";
case DHCPNAK: return "nak";
case DHCPRELEASE: return "release";
case DHCPINFORM: return "inform";
default: return "???";
}
}
void dump_dhcp_info(dhcp_info *info)
{
char addr[20], gway[20];
ALOGD("--- dhcp %s (%d) ---",
dhcp_type_to_name(info->type), info->type);
strcpy(addr, ipaddr(info->ipaddr));
strcpy(gway, ipaddr(info->gateway));
ALOGD("ip %s gw %s prefixLength %d", addr, gway, info->prefixLength);
if (info->dns1) ALOGD("dns1: %s", ipaddr(info->dns1));
if (info->dns2) ALOGD("dns2: %s", ipaddr(info->dns2));
ALOGD("server %s, lease %d seconds",
ipaddr(info->serveraddr), info->lease);
}
int decode_dhcp_msg(dhcp_msg *msg, int len, dhcp_info *info)
{
uint8_t *x;
unsigned int opt;
int optlen;
memset(info, 0, sizeof(dhcp_info));
if (len < (DHCP_MSG_FIXED_SIZE + 4)) return -1;
len -= (DHCP_MSG_FIXED_SIZE + 4);
if (msg->options[0] != OPT_COOKIE1) return -1;
if (msg->options[1] != OPT_COOKIE2) return -1;
if (msg->options[2] != OPT_COOKIE3) return -1;
if (msg->options[3] != OPT_COOKIE4) return -1;
x = msg->options + 4;
while (len > 2) {
opt = *x++;
if (opt == OPT_PAD) {
len--;
continue;
}
if (opt == OPT_END) {
break;
}
optlen = *x++;
len -= 2;
if (optlen > len) {
break;
}
switch(opt) {
case OPT_SUBNET_MASK:
if (optlen >= 4) {
in_addr_t mask;
memcpy(&mask, x, 4);
info->prefixLength = ipv4NetmaskToPrefixLength(mask);
}
break;
case OPT_GATEWAY:
if (optlen >= 4) memcpy(&info->gateway, x, 4);
break;
case OPT_DNS:
if (optlen >= 4) memcpy(&info->dns1, x + 0, 4);
if (optlen >= 8) memcpy(&info->dns2, x + 4, 4);
break;
case OPT_LEASE_TIME:
if (optlen >= 4) {
memcpy(&info->lease, x, 4);
info->lease = ntohl(info->lease);
}
break;
case OPT_SERVER_ID:
if (optlen >= 4) memcpy(&info->serveraddr, x, 4);
break;
case OPT_MESSAGE_TYPE:
info->type = *x;
break;
default:
break;
}
x += optlen;
len -= optlen;
}
info->ipaddr = msg->yiaddr;
return 0;
}
#if VERBOSE
static void hex2str(char *buf, size_t buf_size, const unsigned char *array, int len)
{
int i;
char *cp = buf;
char *buf_end = buf + buf_size;
for (i = 0; i < len; i++) {
cp += snprintf(cp, buf_end - cp, " %02x ", array[i]);
}
}
void dump_dhcp_msg(dhcp_msg *msg, int len)
{
unsigned char *x;
unsigned int n,c;
int optsz;
const char *name;
char buf[2048];
ALOGD("===== DHCP message:");
if (len < DHCP_MSG_FIXED_SIZE) {
ALOGD("Invalid length %d, should be %d", len, DHCP_MSG_FIXED_SIZE);
return;
}
len -= DHCP_MSG_FIXED_SIZE;
if (msg->op == OP_BOOTREQUEST)
name = "BOOTREQUEST";
else if (msg->op == OP_BOOTREPLY)
name = "BOOTREPLY";
else
name = "????";
ALOGD("op = %s (%d), htype = %d, hlen = %d, hops = %d",
name, msg->op, msg->htype, msg->hlen, msg->hops);
ALOGD("xid = 0x%08x secs = %d, flags = 0x%04x optlen = %d",
ntohl(msg->xid), ntohs(msg->secs), ntohs(msg->flags), len);
ALOGD("ciaddr = %s", ipaddr(msg->ciaddr));
ALOGD("yiaddr = %s", ipaddr(msg->yiaddr));
ALOGD("siaddr = %s", ipaddr(msg->siaddr));
ALOGD("giaddr = %s", ipaddr(msg->giaddr));
c = msg->hlen > 16 ? 16 : msg->hlen;
hex2str(buf, sizeof(buf), msg->chaddr, c);
ALOGD("chaddr = {%s}", buf);
for (n = 0; n < 64; n++) {
unsigned char x = msg->sname[n];
if ((x < ' ') || (x > 127)) {
if (x == 0) break;
msg->sname[n] = '.';
}
}
msg->sname[63] = 0;
for (n = 0; n < 128; n++) {
unsigned char x = msg->file[n];
if ((x < ' ') || (x > 127)) {
if (x == 0) break;
msg->file[n] = '.';
}
}
msg->file[127] = 0;
ALOGD("sname = '%s'", msg->sname);
ALOGD("file = '%s'", msg->file);
if (len < 4) return;
len -= 4;
x = msg->options + 4;
while (len > 2) {
if (*x == 0) {
x++;
len--;
continue;
}
if (*x == OPT_END) {
break;
}
len -= 2;
optsz = x[1];
if (optsz > len) break;
if (x[0] == OPT_DOMAIN_NAME || x[0] == OPT_MESSAGE) {
if ((unsigned int)optsz < sizeof(buf) - 1) {
n = optsz;
} else {
n = sizeof(buf) - 1;
}
memcpy(buf, &x[2], n);
buf[n] = '\0';
} else {
hex2str(buf, sizeof(buf), &x[2], optsz);
}
if (x[0] == OPT_MESSAGE_TYPE)
name = dhcp_type_to_name(x[2]);
else
name = NULL;
ALOGD("op %d len %d {%s} %s", x[0], optsz, buf, name == NULL ? "" : name);
len -= optsz;
x = x + optsz + 2;
}
}
#endif
static int send_message(int sock, int if_index, dhcp_msg *msg, int size)
{
#if VERBOSE > 1
dump_dhcp_msg(msg, size);
#endif
return send_packet(sock, if_index, msg, size, INADDR_ANY, INADDR_BROADCAST,
PORT_BOOTP_CLIENT, PORT_BOOTP_SERVER);
}
static int is_valid_reply(dhcp_msg *msg, dhcp_msg *reply, int sz)
{
if (sz < DHCP_MSG_FIXED_SIZE) {
if (verbose) ALOGD("Wrong size %d != %d\n", sz, DHCP_MSG_FIXED_SIZE);
return 0;
}
if (reply->op != OP_BOOTREPLY) {
if (verbose) ALOGD("Wrong Op %d != %d\n", reply->op, OP_BOOTREPLY);
return 0;
}
if (reply->xid != msg->xid) {
if (verbose) ALOGD("Wrong Xid 0x%x != 0x%x\n", ntohl(reply->xid),
ntohl(msg->xid));
return 0;
}
if (reply->htype != msg->htype) {
if (verbose) ALOGD("Wrong Htype %d != %d\n", reply->htype, msg->htype);
return 0;
}
if (reply->hlen != msg->hlen) {
if (verbose) ALOGD("Wrong Hlen %d != %d\n", reply->hlen, msg->hlen);
return 0;
}
if (memcmp(msg->chaddr, reply->chaddr, msg->hlen)) {
if (verbose) ALOGD("Wrong chaddr %x != %x\n", *(reply->chaddr),*(msg->chaddr));
return 0;
}
return 1;
}
#define STATE_SELECTING 1
#define STATE_REQUESTING 2
#define TIMEOUT_INITIAL 4000
#define TIMEOUT_MAX 32000
int dhcp_init_ifc(const char *ifname)
{
dhcp_msg discover_msg;
dhcp_msg request_msg;
dhcp_msg reply;
dhcp_msg *msg;
dhcp_info info;
int s, r, size;
int valid_reply;
uint32_t xid;
unsigned char hwaddr[6];
struct pollfd pfd;
unsigned int state;
unsigned int timeout;
int if_index;
xid = (uint32_t) get_msecs();
if (ifc_get_hwaddr(ifname, hwaddr)) {
return fatal("cannot obtain interface address");
}
if (ifc_get_ifindex(ifname, &if_index)) {
return fatal("cannot obtain interface index");
}
s = open_raw_socket(ifname, hwaddr, if_index);
timeout = TIMEOUT_INITIAL;
state = STATE_SELECTING;
info.type = 0;
goto transmit;
for (;;) {
pfd.fd = s;
pfd.events = POLLIN;
pfd.revents = 0;
r = poll(&pfd, 1, timeout);
if (r == 0) {
#if VERBOSE
printerr("TIMEOUT\n");
#endif
if (timeout >= TIMEOUT_MAX) {
printerr("timed out\n");
if ( info.type == DHCPOFFER ) {
printerr("no acknowledgement from DHCP server\nconfiguring %s with offered parameters\n", ifname);
return dhcp_configure(ifname, &info);
}
errno = ETIME;
close(s);
return -1;
}
timeout = timeout * 2;
transmit:
size = 0;
msg = NULL;
switch(state) {
case STATE_SELECTING:
msg = &discover_msg;
size = init_dhcp_discover_msg(msg, hwaddr, xid);
break;
case STATE_REQUESTING:
msg = &request_msg;
size = init_dhcp_request_msg(msg, hwaddr, xid, info.ipaddr, info.serveraddr);
break;
default:
r = 0;
}
if (size != 0) {
r = send_message(s, if_index, msg, size);
if (r < 0) {
printerr("error sending dhcp msg: %s\n", strerror(errno));
}
}
continue;
}
if (r < 0) {
if ((errno == EAGAIN) || (errno == EINTR)) {
continue;
}
return fatal("poll failed");
}
errno = 0;
r = receive_packet(s, &reply);
if (r < 0) {
if (errno != 0) {
ALOGD("receive_packet failed (%d): %s", r, strerror(errno));
if (errno == ENETDOWN || errno == ENXIO) {
return -1;
}
}
continue;
}
#if VERBOSE > 1
dump_dhcp_msg(&reply, r);
#endif
decode_dhcp_msg(&reply, r, &info);
if (state == STATE_SELECTING) {
valid_reply = is_valid_reply(&discover_msg, &reply, r);
} else {
valid_reply = is_valid_reply(&request_msg, &reply, r);
}
if (!valid_reply) {
printerr("invalid reply\n");
continue;
}
if (verbose) dump_dhcp_info(&info);
switch(state) {
case STATE_SELECTING:
if (info.type == DHCPOFFER) {
state = STATE_REQUESTING;
timeout = TIMEOUT_INITIAL;
xid++;
goto transmit;
}
break;
case STATE_REQUESTING:
if (info.type == DHCPACK) {
printerr("configuring %s\n", ifname);
close(s);
return dhcp_configure(ifname, &info);
} else if (info.type == DHCPNAK) {
printerr("configuration request denied\n");
close(s);
return -1;
} else {
printerr("ignoring %s message in state %d\n",
dhcp_type_to_name(info.type), state);
}
break;
}
}
close(s);
return 0;
}
int do_dhcp(char *iname)
{
if (ifc_set_addr(iname, 0)) {
printerr("failed to set ip addr for %s to 0.0.0.0: %s\n", iname, strerror(errno));
return -1;
}
if (ifc_up(iname)) {
printerr("failed to bring up interface %s: %s\n", iname, strerror(errno));
return -1;
}
return dhcp_init_ifc(iname);
}
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