/* dhcpd.c * * udhcp DHCP client * * Russ Dill July 2001 * * Converted to busybox by Glenn McGrath August 2002 * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * 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., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if __GLIBC__ >=2 && __GLIBC_MINOR >= 1 #include #include #else #include #include #include #endif #include "libbb.h" static int state; static unsigned long requested_ip; /* = 0 */ static unsigned long server_addr; static unsigned long timeout; static int packet_num; /* = 0 */ static int fd_main; /* #define DEBUG */ #define VERSION "0.9.7" #define LISTEN_NONE 0 #define LISTEN_KERNEL 1 #define LISTEN_RAW 2 static int listen_mode; #define DEFAULT_SCRIPT "/usr/share/udhcpc/default.script" #define DHCP_END 0xFF #define TYPE_MASK 0x0F #define BROADCAST_FLAG 0x8000 #define SERVER_PORT 67 #define DHCP_MAGIC 0x63825363 #define BOOTREQUEST 1 #define BOOTREPLY 2 #define ETH_10MB 1 #define ETH_10MB_LEN 6 #define OPTION_FIELD 0 #define FILE_FIELD 1 #define SNAME_FIELD 2 #define INIT_SELECTING 0 #define REQUESTING 1 #define BOUND 2 #define RENEWING 3 #define REBINDING 4 #define INIT_REBOOT 5 #define RENEW_REQUESTED 6 #define RELEASED 7 #define CLIENT_PORT 68 #define DHCPDISCOVER 1 #define DHCPOFFER 2 #define DHCPREQUEST 3 #define DHCPDECLINE 4 #define DHCPACK 5 #define DHCPNAK 6 #define DHCPRELEASE 7 #define DHCPINFORM 8 /* DHCP option codes (partial list) */ #define DHCP_PADDING 0x00 #define DHCP_SUBNET 0x01 #define DHCP_TIME_OFFSET 0x02 #define DHCP_ROUTER 0x03 #define DHCP_TIME_SERVER 0x04 #define DHCP_NAME_SERVER 0x05 #define DHCP_DNS_SERVER 0x06 #define DHCP_LOG_SERVER 0x07 #define DHCP_COOKIE_SERVER 0x08 #define DHCP_LPR_SERVER 0x09 #define DHCP_HOST_NAME 0x0c #define DHCP_BOOT_SIZE 0x0d #define DHCP_DOMAIN_NAME 0x0f #define DHCP_SWAP_SERVER 0x10 #define DHCP_ROOT_PATH 0x11 #define DHCP_IP_TTL 0x17 #define DHCP_MTU 0x1a #define DHCP_BROADCAST 0x1c #define DHCP_NTP_SERVER 0x2a #define DHCP_WINS_SERVER 0x2c #define DHCP_REQUESTED_IP 0x32 #define DHCP_LEASE_TIME 0x33 #define DHCP_OPTION_OVER 0x34 #define DHCP_MESSAGE_TYPE 0x35 #define DHCP_SERVER_ID 0x36 #define DHCP_PARAM_REQ 0x37 #define DHCP_MESSAGE 0x38 #define DHCP_MAX_SIZE 0x39 #define DHCP_T1 0x3a #define DHCP_T2 0x3b #define DHCP_VENDOR 0x3c #define DHCP_CLIENT_ID 0x3d /* miscellaneous defines */ #define MAC_BCAST_ADDR (unsigned char *) "\xff\xff\xff\xff\xff\xff" #define OPT_CODE 0 #define OPT_LEN 1 #define OPT_DATA 2 enum { OPTION_IP = 1, OPTION_IP_PAIR, OPTION_STRING, OPTION_BOOLEAN, OPTION_U8, OPTION_U16, OPTION_S16, OPTION_U32, OPTION_S32 }; #define OPTION_REQ 0x10 /* have the client request this option */ #define OPTION_LIST 0x20 /* There can be a list of 1 or more of these */ #ifdef SYSLOG # define LOG(level, str, args...) do { printf(str, ## args); \ printf("\n"); \ syslog(level, str, ## args); } while(0) # define OPEN_LOG(name) openlog(name, 0, 0) # define CLOSE_LOG() closelog() #else # define LOG_EMERG "EMERGENCY!" # define LOG_ALERT "ALERT!" # define LOG_CRIT "critical!" # define LOG_WARNING "warning" # define LOG_ERR "error" # define LOG_INFO "info" # define LOG_DEBUG "debug" # define LOG(level, str, args...) do { printf("%s, " str "\n", level, ## args); } while(0) # define OPEN_LOG(name) # define CLOSE_LOG() #endif #ifdef DEBUG # undef DEBUG # define DEBUG(level, str, args...) LOG(level, str, ## args) # define DEBUGGING #else # define DEBUG(level, str, args...) #endif struct dhcpMessage { u_int8_t op; u_int8_t htype; u_int8_t hlen; u_int8_t hops; u_int32_t xid; u_int16_t secs; u_int16_t flags; u_int32_t ciaddr; u_int32_t yiaddr; u_int32_t siaddr; u_int32_t giaddr; u_int8_t chaddr[16]; u_int8_t sname[64]; u_int8_t file[128]; u_int32_t cookie; u_int8_t options[308]; /* 312 - cookie */ }; struct client_config_t { char foreground; /* Do not fork */ char quit_after_lease; /* Quit after obtaining lease */ char abort_if_no_lease; /* Abort if no lease */ char *interface; /* The name of the interface to use */ char *pidfile; /* Optionally store the process ID */ char *script; /* User script to run at dhcp events */ unsigned char *clientid; /* Optional client id to use */ unsigned char *hostname; /* Optional hostname to use */ int ifindex; /* Index number of the interface to use */ unsigned char arp[6]; /* Our arp address */ }; struct client_config_t client_config = { /* Default options. */ abort_if_no_lease:0, foreground:0, quit_after_lease:0, interface:"eth0", pidfile:NULL, script:DEFAULT_SCRIPT, clientid:NULL, hostname:NULL, ifindex:0, arp:"\0\0\0\0\0\0", /* appease gcc-3.0 */ }; struct dhcp_option { char name[10]; char flags; unsigned char code; }; struct udp_dhcp_packet { struct iphdr ip; struct udphdr udp; struct dhcpMessage data; }; static const struct dhcp_option options[] = { /* name[10] flags code */ {"subnet", OPTION_IP | OPTION_REQ, 0x01}, {"timezone", OPTION_S32, 0x02}, {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03}, {"timesvr", OPTION_IP | OPTION_LIST, 0x04}, {"namesvr", OPTION_IP | OPTION_LIST, 0x05}, {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06}, {"logsvr", OPTION_IP | OPTION_LIST, 0x07}, {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08}, {"lprsvr", OPTION_IP | OPTION_LIST, 0x09}, {"hostname", OPTION_STRING | OPTION_REQ, 0x0c}, {"bootsize", OPTION_U16, 0x0d}, {"domain", OPTION_STRING | OPTION_REQ, 0x0f}, {"swapsvr", OPTION_IP, 0x10}, {"rootpath", OPTION_STRING, 0x11}, {"ipttl", OPTION_U8, 0x17}, {"mtu", OPTION_U16, 0x1a}, {"broadcast", OPTION_IP | OPTION_REQ, 0x1c}, {"ntpsrv", OPTION_IP | OPTION_LIST, 0x2a}, {"wins", OPTION_IP | OPTION_LIST, 0x2c}, {"requestip", OPTION_IP, 0x32}, {"lease", OPTION_U32, 0x33}, {"dhcptype", OPTION_U8, 0x35}, {"serverid", OPTION_IP, 0x36}, {"message", OPTION_STRING, 0x38}, {"tftp", OPTION_STRING, 0x42}, {"bootfile", OPTION_STRING, 0x43}, {"", 0x00, 0x00} }; /* Lengths of the different option types */ static const unsigned char option_lengths[] = { [OPTION_IP] = 4, [OPTION_IP_PAIR] = 8, [OPTION_BOOLEAN] = 1, [OPTION_STRING] = 1, [OPTION_U8] = 1, [OPTION_U16] = 2, [OPTION_S16] = 2, [OPTION_U32] = 4, [OPTION_S32] = 4 }; /* get a rough idea of how long an option will be (rounding up...) */ static const unsigned char max_option_length[] = { [OPTION_IP] = sizeof("255.255.255.255 "), [OPTION_IP_PAIR] = sizeof("255.255.255.255 ") * 2, [OPTION_STRING] = 1, [OPTION_BOOLEAN] = sizeof("yes "), [OPTION_U8] = sizeof("255 "), [OPTION_U16] = sizeof("65535 "), [OPTION_S16] = sizeof("-32768 "), [OPTION_U32] = sizeof("4294967295 "), [OPTION_S32] = sizeof("-2147483684 "), }; /* return the position of the 'end' option (no bounds checking) */ static int end_option(unsigned char *optionptr) { int i = 0; while (optionptr[i] != DHCP_END) { if (optionptr[i] == DHCP_PADDING) i++; else i += optionptr[i + OPT_LEN] + 2; } return i; } /* add an option string to the options (an option string contains an option code, * length, then data) */ static int add_option_string(unsigned char *optionptr, unsigned char *string) { int end = end_option(optionptr); /* end position + string length + option code/length + end option */ if (end + string[OPT_LEN] + 2 + 1 >= 308) { LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]); return 0; } DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]); memcpy(optionptr + end, string, string[OPT_LEN] + 2); optionptr[end + string[OPT_LEN] + 2] = DHCP_END; return string[OPT_LEN] + 2; } /* add a one to four byte option to a packet */ static int add_simple_option(unsigned char *optionptr, unsigned char code, u_int32_t data) { char length = 0; int i; unsigned char option[2 + 4]; unsigned char *u8; u_int16_t *u16; u_int32_t *u32; u_int32_t aligned; u8 = (unsigned char *) &aligned; u16 = (u_int16_t *) & aligned; u32 = &aligned; for (i = 0; options[i].code; i++) if (options[i].code == code) { length = option_lengths[options[i].flags & TYPE_MASK]; } if (!length) { DEBUG(LOG_ERR, "Could not add option 0x%02x", code); return 0; } option[OPT_CODE] = code; option[OPT_LEN] = length; switch (length) { case 1: *u8 = data; break; case 2: *u16 = data; break; case 4: *u32 = data; break; } memcpy(option + 2, &aligned, length); return add_option_string(optionptr, option); } static u_int16_t checksum(void *addr, int count) { /* Compute Internet Checksum for "count" bytes * beginning at location "addr". */ register int32_t sum = 0; u_int16_t *source = (u_int16_t *) addr; while (count > 1) { /* This is the inner loop */ sum += *source++; count -= 2; } /* Add left-over byte, if any */ if (count > 0) { sum += *(unsigned char *) source; } /* Fold 32-bit sum to 16 bits */ while (sum >> 16) { sum = (sum & 0xffff) + (sum >> 16); } return ~sum; } /* Constuct a ip/udp header for a packet, and specify the source and dest hardware address */ static int raw_packet(struct dhcpMessage *payload, u_int32_t source_ip, int source_port, u_int32_t dest_ip, int dest_port, unsigned char *dest_arp, int ifindex) { int l_fd; int result; struct sockaddr_ll dest; struct udp_dhcp_packet packet; if ((l_fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) { DEBUG(LOG_ERR, "socket call failed: %s", strerror(errno)); return -1; } memset(&dest, 0, sizeof(dest)); memset(&packet, 0, sizeof(packet)); dest.sll_family = AF_PACKET; dest.sll_protocol = htons(ETH_P_IP); dest.sll_ifindex = ifindex; dest.sll_halen = 6; memcpy(dest.sll_addr, dest_arp, 6); if (bind(l_fd, (struct sockaddr *) &dest, sizeof(struct sockaddr_ll)) < 0) { DEBUG(LOG_ERR, "bind call failed: %s", strerror(errno)); close(l_fd); return -1; } packet.ip.protocol = IPPROTO_UDP; packet.ip.saddr = source_ip; packet.ip.daddr = dest_ip; packet.udp.source = htons(source_port); packet.udp.dest = htons(dest_port); packet.udp.len = htons(sizeof(packet.udp) + sizeof(struct dhcpMessage)); /* cheat on the psuedo-header */ packet.ip.tot_len = packet.udp.len; memcpy(&(packet.data), payload, sizeof(struct dhcpMessage)); packet.udp.check = checksum(&packet, sizeof(struct udp_dhcp_packet)); packet.ip.tot_len = htons(sizeof(struct udp_dhcp_packet)); packet.ip.ihl = sizeof(packet.ip) >> 2; packet.ip.version = IPVERSION; packet.ip.ttl = IPDEFTTL; packet.ip.check = checksum(&(packet.ip), sizeof(packet.ip)); result = sendto(l_fd, &packet, sizeof(struct udp_dhcp_packet), 0, (struct sockaddr *) &dest, sizeof(dest)); if (result <= 0) { DEBUG(LOG_ERR, "write on socket failed: %s", strerror(errno)); } close(l_fd); return result; } /* Let the kernel do all the work for packet generation */ static int kernel_packet(struct dhcpMessage *payload, u_int32_t source_ip, int source_port, u_int32_t dest_ip, int dest_port) { int n = 1; int l_fd, result; struct sockaddr_in client; if ((l_fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) { return -1; } if (setsockopt(l_fd, SOL_SOCKET, SO_REUSEADDR, (char *) &n, sizeof(n)) == -1) { return -1; } memset(&client, 0, sizeof(client)); client.sin_family = AF_INET; client.sin_port = htons(source_port); client.sin_addr.s_addr = source_ip; if (bind(l_fd, (struct sockaddr *) &client, sizeof(struct sockaddr)) == -1) { return -1; } memset(&client, 0, sizeof(client)); client.sin_family = AF_INET; client.sin_port = htons(dest_port); client.sin_addr.s_addr = dest_ip; if (connect(l_fd, (struct sockaddr *) &client, sizeof(struct sockaddr)) == -1) { return -1; } result = write(l_fd, payload, sizeof(struct dhcpMessage)); close(l_fd); return result; } /* initialize a packet with the proper defaults */ static void init_packet(struct dhcpMessage *packet, char type) { struct vendor { char vendor, length; char str[sizeof("udhcp " VERSION)]; } vendor_id = { DHCP_VENDOR, sizeof("udhcp " VERSION) - 1, "udhcp " VERSION}; memset(packet, 0, sizeof(struct dhcpMessage)); switch (type) { case DHCPDISCOVER: case DHCPREQUEST: case DHCPRELEASE: case DHCPINFORM: packet->op = BOOTREQUEST; break; case DHCPOFFER: case DHCPACK: case DHCPNAK: packet->op = BOOTREPLY; } packet->htype = ETH_10MB; packet->hlen = ETH_10MB_LEN; packet->cookie = htonl(DHCP_MAGIC); packet->options[0] = DHCP_END; add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type); memcpy(packet->chaddr, client_config.arp, 6); add_option_string(packet->options, client_config.clientid); if (client_config.hostname) { add_option_string(packet->options, client_config.hostname); } add_option_string(packet->options, (unsigned char *) &vendor_id); } /* Add a paramater request list for stubborn DHCP servers. Pull the data * from the struct in options.c. Don't do bounds checking here because it * goes towards the head of the packet. */ static void add_requests(struct dhcpMessage *packet) { int end = end_option(packet->options); int i, len = 0; packet->options[end + OPT_CODE] = DHCP_PARAM_REQ; for (i = 0; options[i].code; i++) { if (options[i].flags & OPTION_REQ) { packet->options[end + OPT_DATA + len++] = options[i].code; } } packet->options[end + OPT_LEN] = len; packet->options[end + OPT_DATA + len] = DHCP_END; } /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */ static inline int send_discover(unsigned long xid, unsigned long requested) { struct dhcpMessage packet; init_packet(&packet, DHCPDISCOVER); packet.xid = xid; if (requested) { add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); } add_requests(&packet); DEBUG(LOG_DEBUG, "Sending discover..."); return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); } /* Broadcasts a DHCP request message */ static inline int send_selecting(unsigned long xid, unsigned long server, unsigned long requested) { struct dhcpMessage packet; struct in_addr addr; init_packet(&packet, DHCPREQUEST); packet.xid = xid; add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); add_simple_option(packet.options, DHCP_SERVER_ID, server); add_requests(&packet); addr.s_addr = requested; DEBUG(LOG_DEBUG, "Sending select for %s...", inet_ntoa(addr)); return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); } /* Unicasts or broadcasts a DHCP renew message */ static int send_renew(unsigned long xid, unsigned long server, unsigned long ciaddr) { struct dhcpMessage packet; init_packet(&packet, DHCPREQUEST); packet.xid = xid; packet.ciaddr = ciaddr; add_requests(&packet); DEBUG(LOG_DEBUG, "Sending renew..."); if (server) { return kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT); } return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); } /* Create a random xid */ static unsigned long random_xid(void) { static int initialized; if (!initialized) { srand(time(0)); initialized++; } return rand(); } /* just a little helper */ static void change_mode(int new_mode) { DEBUG(LOG_INFO, "entering %s listen mode", new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none"); close(fd_main); fd_main = -1; listen_mode = new_mode; } /* SIGUSR1 handler (renew) */ static void renew_requested(int sig) { sig = 0; LOG(LOG_INFO, "Received SIGUSR1"); if (state == BOUND || state == RENEWING || state == REBINDING || state == RELEASED) { change_mode(LISTEN_KERNEL); packet_num = 0; state = RENEW_REQUESTED; } if (state == RELEASED) { change_mode(LISTEN_RAW); state = INIT_SELECTING; } /* Kill any timeouts because the user wants this to hurry along */ timeout = 0; } /* get an option with bounds checking (warning, not aligned). */ static unsigned char *get_option(struct dhcpMessage *packet, int code) { int i, length; unsigned char *optionptr; int over = 0, done = 0, curr = OPTION_FIELD; optionptr = packet->options; i = 0; length = 308; while (!done) { if (i >= length) { LOG(LOG_WARNING, "bogus packet, option fields too long."); return NULL; } if (optionptr[i + OPT_CODE] == code) { if (i + 1 + optionptr[i + OPT_LEN] >= length) { LOG(LOG_WARNING, "bogus packet, option fields too long."); return NULL; } return optionptr + i + 2; } switch (optionptr[i + OPT_CODE]) { case DHCP_PADDING: i++; break; case DHCP_OPTION_OVER: if (i + 1 + optionptr[i + OPT_LEN] >= length) { LOG(LOG_WARNING, "bogus packet, option fields too long."); return NULL; } over = optionptr[i + 3]; i += optionptr[OPT_LEN] + 2; break; case DHCP_END: if (curr == OPTION_FIELD && over & FILE_FIELD) { optionptr = packet->file; i = 0; length = 128; curr = FILE_FIELD; } else if (curr == FILE_FIELD && over & SNAME_FIELD) { optionptr = packet->sname; i = 0; length = 64; curr = SNAME_FIELD; } else { done = 1; } break; default: i += optionptr[OPT_LEN + i] + 2; } } return NULL; } static int sprintip(char *dest, char *pre, unsigned char *ip) { return sprintf(dest, "%s%d.%d.%d.%d ", pre, ip[0], ip[1], ip[2], ip[3]); } /* Fill dest with the text of option 'option'. */ static inline void fill_options(char *dest, unsigned char *option, const struct dhcp_option *type_p) { int type, optlen; u_int16_t val_u16; int16_t val_s16; u_int32_t val_u32; int32_t val_s32; int len = option[OPT_LEN - 2]; dest += sprintf(dest, "%s=", type_p->name); type = type_p->flags & TYPE_MASK; optlen = option_lengths[type]; for (;;) { switch (type) { case OPTION_IP_PAIR: dest += sprintip(dest, "", option); *(dest++) = '/'; option += 4; optlen = 4; case OPTION_IP: /* Works regardless of host byte order. */ dest += sprintip(dest, "", option); break; case OPTION_BOOLEAN: dest += sprintf(dest, *option ? "yes " : "no "); break; case OPTION_U8: dest += sprintf(dest, "%u ", *option); break; case OPTION_U16: memcpy(&val_u16, option, 2); dest += sprintf(dest, "%u ", ntohs(val_u16)); break; case OPTION_S16: memcpy(&val_s16, option, 2); dest += sprintf(dest, "%d ", ntohs(val_s16)); break; case OPTION_U32: memcpy(&val_u32, option, 4); dest += sprintf(dest, "%lu ", (unsigned long) ntohl(val_u32)); break; case OPTION_S32: memcpy(&val_s32, option, 4); dest += sprintf(dest, "%ld ", (long) ntohl(val_s32)); break; case OPTION_STRING: memcpy(dest, option, len); dest[len] = '\0'; return; /* Short circuit this case */ } option += optlen; len -= optlen; if (len <= 0) { break; } } } static char *find_env(const char *prefix, char *defaultstr) { extern char **environ; char **ptr; const int len = strlen(prefix); for (ptr = environ; *ptr != NULL; ptr++) { if (strncmp(prefix, *ptr, len) == 0) { return *ptr; } } return defaultstr; } /* put all the paramaters into an environment */ static char **fill_envp(struct dhcpMessage *packet) { /* supported options are easily added here */ int num_options = 0; int i, j; char **envp; unsigned char *temp; char over = 0; if (packet == NULL) { num_options = 0; } else { for (i = 0; options[i].code; i++) { if (get_option(packet, options[i].code)) { num_options++; } } if (packet->siaddr) { num_options++; } if ((temp = get_option(packet, DHCP_OPTION_OVER))) { over = *temp; } if (!(over & FILE_FIELD) && packet->file[0]) { num_options++; } if (!(over & SNAME_FIELD) && packet->sname[0]) { num_options++; } } envp = xmalloc((num_options + 5) * sizeof(char *)); envp[0] = xmalloc(sizeof("interface=") + strlen(client_config.interface)); sprintf(envp[0], "interface=%s", client_config.interface); envp[1] = find_env("PATH", "PATH=/bin:/usr/bin:/sbin:/usr/sbin"); envp[2] = find_env("HOME", "HOME=/"); if (packet == NULL) { envp[3] = NULL; return envp; } envp[3] = xmalloc(sizeof("ip=255.255.255.255")); sprintip(envp[3], "ip=", (unsigned char *) &packet->yiaddr); for (i = 0, j = 4; options[i].code; i++) { if ((temp = get_option(packet, options[i].code))) { envp[j] = xmalloc(max_option_length[(&options[i])->flags & TYPE_MASK] * (temp[OPT_LEN - 2] / option_lengths[(&options[i])->flags & TYPE_MASK]) + strlen((&options[i])->name) + 2); fill_options(envp[j], temp, &options[i]); j++; } } if (packet->siaddr) { envp[j] = xmalloc(sizeof("siaddr=255.255.255.255")); sprintip(envp[j++], "siaddr=", (unsigned char *) &packet->yiaddr); } if (!(over & FILE_FIELD) && packet->file[0]) { /* watch out for invalid packets */ packet->file[sizeof(packet->file) - 1] = '\0'; envp[j] = xmalloc(sizeof("boot_file=") + strlen(packet->file)); sprintf(envp[j++], "boot_file=%s", packet->file); } if (!(over & SNAME_FIELD) && packet->sname[0]) { /* watch out for invalid packets */ packet->sname[sizeof(packet->sname) - 1] = '\0'; envp[j] = xmalloc(sizeof("sname=") + strlen(packet->sname)); sprintf(envp[j++], "sname=%s", packet->sname); } envp[j] = NULL; return envp; } /* Call a script with a par file and env vars */ static void run_script(struct dhcpMessage *packet, const char *name) { int pid; char **envp; if (client_config.script == NULL) { return; } /* call script */ pid = fork(); if (pid) { waitpid(pid, NULL, 0); return; } else if (pid == 0) { envp = fill_envp(packet); /* close fd's? */ /* exec script */ DEBUG(LOG_INFO, "execle'ing %s", client_config.script); execle(client_config.script, client_config.script, name, NULL, envp); LOG(LOG_ERR, "script %s failed: %s", client_config.script, strerror(errno)); exit(1); } } /* SIGUSR2 handler (release) */ static void release_requested(int sig) { sig = 0; LOG(LOG_INFO, "Received SIGUSR2"); /* send release packet */ if (state == BOUND || state == RENEWING || state == REBINDING) { struct dhcpMessage packet; init_packet(&packet, DHCPRELEASE); packet.xid = random_xid(); packet.ciaddr = requested_ip; add_simple_option(packet.options, DHCP_REQUESTED_IP, requested_ip); add_simple_option(packet.options, DHCP_SERVER_ID, server_addr); DEBUG(LOG_DEBUG, "Sending release..."); kernel_packet(&packet, requested_ip, CLIENT_PORT, server_addr, SERVER_PORT); run_script(NULL, "deconfig"); } change_mode(LISTEN_NONE); state = RELEASED; timeout = 0x7fffffff; } static int pidfile_acquire(char *pidfile) { int pid_fd; if (pidfile == NULL) { return -1; } pid_fd = open(pidfile, O_CREAT | O_WRONLY, 0644); if (pid_fd < 0) { LOG(LOG_ERR, "Unable to open pidfile %s: %s\n", pidfile, strerror(errno)); } else { lockf(pid_fd, F_LOCK, 0); } return pid_fd; } static void pidfile_write_release(int pid_fd) { FILE *out; if (pid_fd < 0) { return; } if ((out = fdopen(pid_fd, "w")) != NULL) { fprintf(out, "%d\n", getpid()); fclose(out); } lockf(pid_fd, F_UNLCK, 0); close(pid_fd); } /* Exit and cleanup */ static void exit_client(int retval) { unlink(client_config.pidfile); if (client_config.pidfile) { unlink(client_config.pidfile); } CLOSE_LOG(); exit(retval); } /* SIGTERM handler */ static void terminate(int sig) { sig = 0; LOG(LOG_INFO, "Received SIGTERM"); exit_client(0); } static inline int read_interface(char *interface, int *ifindex, u_int32_t * addr, unsigned char *arp) { int l_fd; struct ifreq ifr; struct sockaddr_in *s_in; memset(&ifr, 0, sizeof(struct ifreq)); if ((l_fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) >= 0) { ifr.ifr_addr.sa_family = AF_INET; strcpy(ifr.ifr_name, interface); if (addr) { if (ioctl(l_fd, SIOCGIFADDR, &ifr) == 0) { s_in = (struct sockaddr_in *) &ifr.ifr_addr; *addr = s_in->sin_addr.s_addr; DEBUG(LOG_INFO, "%s (our ip) = %s", ifr.ifr_name, inet_ntoa(s_in->sin_addr)); } else { LOG(LOG_ERR, "SIOCGIFADDR failed!: %s", strerror(errno)); return -1; } } if (ioctl(l_fd, SIOCGIFINDEX, &ifr) == 0) { DEBUG(LOG_INFO, "adapter index %d", ifr.ifr_ifindex); *ifindex = ifr.ifr_ifindex; } else { LOG(LOG_ERR, "SIOCGIFINDEX failed!: %s", strerror(errno)); return -1; } if (ioctl(l_fd, SIOCGIFHWADDR, &ifr) == 0) { memcpy(arp, ifr.ifr_hwaddr.sa_data, 6); DEBUG(LOG_INFO, "adapter hardware address %02x:%02x:%02x:%02x:%02x:%02x", arp[0], arp[1], arp[2], arp[3], arp[4], arp[5]); } else { LOG(LOG_ERR, "SIOCGIFHWADDR failed!: %s", strerror(errno)); return -1; } } else { LOG(LOG_ERR, "socket failed!: %s", strerror(errno)); return -1; } close(l_fd); return 0; } static inline int listen_socket(unsigned int ip, int port, char *inf) { struct ifreq interface; int l_fd; struct sockaddr_in addr; int n = 1; DEBUG(LOG_INFO, "Opening listen socket on 0x%08x:%d %s\n", ip, port, inf); if ((l_fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) { DEBUG(LOG_ERR, "socket call failed: %s", strerror(errno)); return -1; } memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_port = htons(port); addr.sin_addr.s_addr = ip; if (setsockopt(l_fd, SOL_SOCKET, SO_REUSEADDR, (char *) &n, sizeof(n)) == -1) { close(l_fd); return -1; } if (setsockopt(l_fd, SOL_SOCKET, SO_BROADCAST, (char *) &n, sizeof(n)) == -1) { close(l_fd); return -1; } strncpy(interface.ifr_ifrn.ifrn_name, inf, IFNAMSIZ); if (setsockopt (l_fd, SOL_SOCKET, SO_BINDTODEVICE, (char *) &interface, sizeof(interface)) < 0) { close(l_fd); return -1; } if (bind(l_fd, (struct sockaddr *) &addr, sizeof(struct sockaddr)) == -1) { close(l_fd); return -1; } return l_fd; } static int raw_socket(int ifindex) { int l_fd; struct sockaddr_ll sock; DEBUG(LOG_INFO, "Opening raw socket on ifindex %d\n", ifindex); if ((l_fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) { DEBUG(LOG_ERR, "socket call failed: %s", strerror(errno)); return -1; } sock.sll_family = AF_PACKET; sock.sll_protocol = htons(ETH_P_IP); sock.sll_ifindex = ifindex; if (bind(l_fd, (struct sockaddr *) &sock, sizeof(sock)) < 0) { DEBUG(LOG_ERR, "bind call failed: %s", strerror(errno)); close(l_fd); return -1; } return l_fd; } /* read a packet from socket fd, return -1 on read error, -2 on packet error */ static int get_packet(struct dhcpMessage *packet, int l_fd) { int bytes; int i; const char broken_vendors[][8] = { "MSFT 98", "" }; char unsigned *vendor; memset(packet, 0, sizeof(struct dhcpMessage)); bytes = read(l_fd, packet, sizeof(struct dhcpMessage)); if (bytes < 0) { DEBUG(LOG_INFO, "couldn't read on listening socket, ignoring"); return -1; } if (ntohl(packet->cookie) != DHCP_MAGIC) { LOG(LOG_ERR, "received bogus message, ignoring"); return -2; } DEBUG(LOG_INFO, "Received a packet"); if (packet->op == BOOTREQUEST && (vendor = get_option(packet, DHCP_VENDOR))) { for (i = 0; broken_vendors[i][0]; i++) { if (vendor[OPT_LEN - 2] == (unsigned char) strlen(broken_vendors[i]) && !strncmp(vendor, broken_vendors[i], vendor[OPT_LEN - 2])) { DEBUG(LOG_INFO, "broken client (%s), forcing broadcast", broken_vendors[i]); packet->flags |= htons(BROADCAST_FLAG); } } } return bytes; } static inline int get_raw_packet(struct dhcpMessage *payload, int l_fd) { int bytes; struct udp_dhcp_packet packet; u_int32_t source, dest; u_int16_t check; memset(&packet, 0, sizeof(struct udp_dhcp_packet)); bytes = read(l_fd, &packet, sizeof(struct udp_dhcp_packet)); if (bytes < 0) { DEBUG(LOG_INFO, "couldn't read on raw listening socket -- ignoring"); usleep(500000); /* possible down interface, looping condition */ return -1; } if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) { DEBUG(LOG_INFO, "message too short, ignoring"); return -1; } if (bytes < ntohs(packet.ip.tot_len)) { DEBUG(LOG_INFO, "Truncated packet"); return -1; } /* ignore any extra garbage bytes */ bytes = ntohs(packet.ip.tot_len); /* Make sure its the right packet for us, and that it passes sanity checks */ if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION || packet.ip.ihl != sizeof(packet.ip) >> 2 || packet.udp.dest != htons(CLIENT_PORT) || bytes > (int) sizeof(struct udp_dhcp_packet) || ntohs(packet.udp.len) != (short) (bytes - sizeof(packet.ip))) { DEBUG(LOG_INFO, "unrelated/bogus packet"); return -1; } /* check IP checksum */ check = packet.ip.check; packet.ip.check = 0; if (check != checksum(&(packet.ip), sizeof(packet.ip))) { DEBUG(LOG_INFO, "bad IP header checksum, ignoring"); return -1; } /* verify the UDP checksum by replacing the header with a psuedo header */ source = packet.ip.saddr; dest = packet.ip.daddr; check = packet.udp.check; packet.udp.check = 0; memset(&packet.ip, 0, sizeof(packet.ip)); packet.ip.protocol = IPPROTO_UDP; packet.ip.saddr = source; packet.ip.daddr = dest; packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */ if (check && check != checksum(&packet, bytes)) { DEBUG(LOG_ERR, "packet with bad UDP checksum received, ignoring"); return -1; } memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp))); if (ntohl(payload->cookie) != DHCP_MAGIC) { LOG(LOG_ERR, "received bogus message (bad magic) -- ignoring"); return -1; } DEBUG(LOG_INFO, "oooooh!!! got some!"); return bytes - (sizeof(packet.ip) + sizeof(packet.udp)); } int udhcpc_main(int argc, char *argv[]) { unsigned char *temp, *message; unsigned long t1 = 0, t2 = 0, xid = 0; unsigned long start = 0, lease; fd_set rfds; int retval; struct timeval tv; int c, len; struct dhcpMessage packet; struct in_addr temp_addr; int pid_fd; time_t now; static struct option l_options[] = { {"clientid", required_argument, 0, 'c'}, {"foreground", no_argument, 0, 'f'}, {"hostname", required_argument, 0, 'H'}, {"help", no_argument, 0, 'h'}, {"interface", required_argument, 0, 'i'}, {"now", no_argument, 0, 'n'}, {"pidfile", required_argument, 0, 'p'}, {"quit", no_argument, 0, 'q'}, {"request", required_argument, 0, 'r'}, {"script", required_argument, 0, 's'}, {"version", no_argument, 0, 'v'}, {0, 0, 0, 0} }; /* get options */ while (1) { int option_index = 0; c = getopt_long(argc, argv, "c:fH:i:np:qr:s:v", l_options, &option_index); if (c == -1) { break; } switch (c) { case 'c': len = strlen(optarg); if (len > 255) { len = 255; } if (client_config.clientid) { free(client_config.clientid); } client_config.clientid = xmalloc(len + 2); client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID; client_config.clientid[OPT_LEN] = len; client_config.clientid[OPT_DATA] = '\0'; strncpy(client_config.clientid + 3, optarg, len - 1); break; case 'f': client_config.foreground = 1; break; case 'H': len = strlen(optarg); if (len > 255) { len = 255; } if (client_config.hostname) { free(client_config.hostname); } client_config.hostname = xmalloc(len + 2); client_config.hostname[OPT_CODE] = DHCP_HOST_NAME; client_config.hostname[OPT_LEN] = len; strncpy(client_config.hostname + 2, optarg, len); break; case 'i': client_config.interface = optarg; break; case 'n': client_config.abort_if_no_lease = 1; break; case 'p': client_config.pidfile = optarg; break; case 'q': client_config.quit_after_lease = 1; break; case 'r': requested_ip = inet_addr(optarg); break; case 's': client_config.script = optarg; break; case 'v': printf("udhcpcd, version %s\n\n", VERSION); exit_client(0); break; default: show_usage(); } } OPEN_LOG("udhcpc"); LOG(LOG_INFO, "udhcp client (v%s) started", VERSION); pid_fd = pidfile_acquire(client_config.pidfile); pidfile_write_release(pid_fd); if (read_interface (client_config.interface, &client_config.ifindex, NULL, client_config.arp) < 0) { exit_client(1); } if (!client_config.clientid) { client_config.clientid = xmalloc(6 + 3); client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID; client_config.clientid[OPT_LEN] = 7; client_config.clientid[OPT_DATA] = 1; memcpy(client_config.clientid + 3, client_config.arp, 6); } /* setup signal handlers */ signal(SIGUSR1, renew_requested); signal(SIGUSR2, release_requested); signal(SIGTERM, terminate); state = INIT_SELECTING; run_script(NULL, "deconfig"); change_mode(LISTEN_RAW); for (;;) { tv.tv_sec = timeout - time(0); tv.tv_usec = 0; FD_ZERO(&rfds); if (listen_mode != LISTEN_NONE && fd_main < 0) { if (listen_mode == LISTEN_KERNEL) { fd_main = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface); } else { fd_main = raw_socket(client_config.ifindex); } if (fd_main < 0) { LOG(LOG_ERR, "FATAL: couldn't listen on socket, %s", strerror(errno)); exit_client(0); } } if (fd_main >= 0) { FD_SET(fd_main, &rfds); } if (tv.tv_sec > 0) { DEBUG(LOG_INFO, "Waiting on select...\n"); retval = select(fd_main + 1, &rfds, NULL, NULL, &tv); } else { retval = 0; /* If we already timed out, fall through */ } now = time(0); if (retval == 0) { /* timeout dropped to zero */ switch (state) { case INIT_SELECTING: if (packet_num < 3) { if (packet_num == 0) { xid = random_xid(); } /* send discover packet */ send_discover(xid, requested_ip); /* broadcast */ timeout = now + ((packet_num == 2) ? 10 : 2); packet_num++; } else { if (client_config.abort_if_no_lease) { LOG(LOG_INFO, "No lease, failing."); exit_client(1); } /* wait to try again */ packet_num = 0; timeout = now + 60; } break; case RENEW_REQUESTED: case REQUESTING: if (packet_num < 3) { /* send request packet */ if (state == RENEW_REQUESTED) { send_renew(xid, server_addr, requested_ip); /* unicast */ } else { send_selecting(xid, server_addr, requested_ip); /* broadcast */ } timeout = now + ((packet_num == 2) ? 10 : 2); packet_num++; } else { /* timed out, go back to init state */ state = INIT_SELECTING; timeout = now; packet_num = 0; change_mode(LISTEN_RAW); } break; case BOUND: /* Lease is starting to run out, time to enter renewing state */ state = RENEWING; change_mode(LISTEN_KERNEL); DEBUG(LOG_INFO, "Entering renew state"); /* fall right through */ case RENEWING: /* Either set a new T1, or enter REBINDING state */ if ((t2 - t1) <= (lease / 14400 + 1)) { /* timed out, enter rebinding state */ state = REBINDING; timeout = now + (t2 - t1); DEBUG(LOG_INFO, "Entering rebinding state"); } else { /* send a request packet */ send_renew(xid, server_addr, requested_ip); /* unicast */ t1 = (t2 - t1) / 2 + t1; timeout = t1 + start; } break; case REBINDING: /* Either set a new T2, or enter INIT state */ if ((lease - t2) <= (lease / 14400 + 1)) { /* timed out, enter init state */ state = INIT_SELECTING; LOG(LOG_INFO, "Lease lost, entering init state"); run_script(NULL, "deconfig"); timeout = now; packet_num = 0; change_mode(LISTEN_RAW); } else { /* send a request packet */ send_renew(xid, 0, requested_ip); /* broadcast */ t2 = (lease - t2) / 2 + t2; timeout = t2 + start; } break; case RELEASED: /* yah, I know, *you* say it would never happen */ timeout = 0x7fffffff; break; } } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd_main, &rfds)) { /* a packet is ready, read it */ if (listen_mode == LISTEN_KERNEL) { len = get_packet(&packet, fd_main); } else { len = get_raw_packet(&packet, fd_main); } if (len == -1 && errno != EINTR) { DEBUG(LOG_INFO, "error on read, %s, reopening socket", strerror(errno)); change_mode(listen_mode); /* just close and reopen */ } if (len < 0) { continue; } if (packet.xid != xid) { DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)", (unsigned long) packet.xid, xid); continue; } if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) { DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring"); continue; } switch (state) { case INIT_SELECTING: /* Must be a DHCPOFFER to one of our xid's */ if (*message == DHCPOFFER) { if ((temp = get_option(&packet, DHCP_SERVER_ID))) { memcpy(&server_addr, temp, 4); xid = packet.xid; requested_ip = packet.yiaddr; /* enter requesting state */ state = REQUESTING; timeout = now; packet_num = 0; } else { DEBUG(LOG_ERR, "No server ID in message"); } } break; case RENEW_REQUESTED: case REQUESTING: case RENEWING: case REBINDING: if (*message == DHCPACK) { if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) { LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease"); lease = 60 * 60; } else { memcpy(&lease, temp, 4); lease = ntohl(lease); } /* enter bound state */ t1 = lease / 2; /* little fixed point for n * .875 */ t2 = (lease * 0x7) >> 3; temp_addr.s_addr = packet.yiaddr; LOG(LOG_INFO, "Lease of %s obtained, lease time %ld", inet_ntoa(temp_addr), lease); start = now; timeout = t1 + start; requested_ip = packet.yiaddr; run_script(&packet, ((state == RENEWING || state == REBINDING) ? "renew" : "bound")); state = BOUND; change_mode(LISTEN_NONE); { int pid_fd2; if (client_config.quit_after_lease) { exit_client(0); } else if (!client_config.foreground) { pid_fd2 = pidfile_acquire(client_config.pidfile); /* hold lock during fork. */ if (daemon(0, 0) == -1) { perror("fork"); exit_client(1); } client_config.foreground = 1; /* Do not fork again. */ pidfile_write_release(pid_fd2); } } } else if (*message == DHCPNAK) { /* return to init state */ LOG(LOG_INFO, "Received DHCP NAK"); run_script(&packet, "nak"); if (state != REQUESTING) { run_script(NULL, "deconfig"); } state = INIT_SELECTING; timeout = now; requested_ip = 0; packet_num = 0; change_mode(LISTEN_RAW); sleep(3); /* avoid excessive network traffic */ } break; /* case BOUND, RELEASED: - ignore all packets */ } } else if (retval == -1 && errno == EINTR) { /* a signal was caught */ } else { /* An error occured */ DEBUG(LOG_ERR, "Error on select"); } } return 0; }