/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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); }