/* dhcpd.c - DHCP server for dynamic network configuration. * * Copyright 2013 Madhur Verma * Copyright 2013 Kyungwan Han * * No Standard USE_DHCPD(NEWTOY(dhcpd, ">1P#<0>65535=67fS", TOYFLAG_SBIN|TOYFLAG_ROOTONLY)) config DHCPD bool "dhcpd" default n help usage: dhcpd [-fS] [-P N] [CONFFILE] -f Run in foreground -S Log to syslog too -P N Use port N (default 67) config DEBUG_DHCP bool "debugging messeges ON/OFF" default n depends on DHCPD */ #define FOR_dhcpd #include "toys.h" #include #include // Todo: headers not in posix #include #include #include #if CFG_DEBUG_DHCP==1 # define dbg(fmt, arg...) printf(fmt, ##arg) #else # define dbg(fmt, arg...) #endif #define flag_get(f,v,d) ((toys.optflags & (f)) ? (v) : (d)) #define flag_chk(f) ((toys.optflags & (f)) ? 1 : 0) #define LOG_SILENT 0x0 #define LOG_CONSOLE 0x1 #define LOG_SYSTEM 0x2 #define DHCP_MAGIC 0x63825363 #define DHCPDISCOVER 1 #define DHCPOFFER 2 #define DHCPREQUEST 3 #define DHCPDECLINE 4 #define DHCPACK 5 #define DHCPNAK 6 #define DHCPRELEASE 7 #define DHCPINFORM 8 #define DHCP_NUM8 (1<<8) #define DHCP_NUM16 (1<<9) #define DHCP_NUM32 DHCP_NUM16 | DHCP_NUM8 #define DHCP_STRING (1<<10) #define DHCP_STRLST (1<<11) #define DHCP_IP (1<<12) #define DHCP_IPLIST (1<<13) #define DHCP_IPPLST (1<<14) #define DHCP_STCRTS (1<<15) // DHCP option codes (partial list). See RFC 2132 and #define DHCP_OPT_PADDING 0x00 #define DHCP_OPT_HOST_NAME DHCP_STRING | 0x0c // either client informs server or server gives name to client #define DHCP_OPT_REQUESTED_IP DHCP_IP | 0x32 // sent by client if specific IP is wanted #define DHCP_OPT_LEASE_TIME DHCP_NUM32 | 0x33 #define DHCP_OPT_OPTION_OVERLOAD 0x34 #define DHCP_OPT_MESSAGE_TYPE DHCP_NUM8 | 0x35 #define DHCP_OPT_SERVER_ID DHCP_IP | 0x36 // by default server's IP #define DHCP_OPT_PARAM_REQ DHCP_STRING | 0x37 // list of options client wants #define DHCP_OPT_END 0xff GLOBALS( long port; ); typedef struct __attribute__((packed)) dhcp_msg_s { uint8_t op; uint8_t htype; uint8_t hlen; uint8_t hops; uint32_t xid; uint16_t secs; uint16_t flags; uint32_t ciaddr; uint32_t yiaddr; uint32_t nsiaddr; uint32_t ngiaddr; uint8_t chaddr[16]; uint8_t sname[64]; uint8_t file[128]; uint32_t cookie; uint8_t options[308]; } dhcp_msg_t; typedef struct __attribute__((packed)) dhcp_raw_s { struct iphdr iph; struct udphdr udph; dhcp_msg_t dhcp; } dhcp_raw_t; typedef struct static_lease_s { struct static_lease_s *next; uint32_t nip; int mac[6]; } static_lease; typedef struct { uint32_t expires; uint32_t lease_nip; uint8_t lease_mac[6]; char hostname[20]; uint8_t pad[2]; } dyn_lease; typedef struct option_val_s { char *key; uint16_t code; void *val; size_t len; } option_val_t; typedef struct __attribute__((__may_alias__)) server_config_s { char *interface; // interface to use int ifindex; uint32_t server_nip; uint32_t port; uint8_t server_mac[6]; // our MAC address (used only for ARP probing) void *options[256]; // list of DHCP options loaded from the config file /* start,end are in host order: we need to compare start <= ip <= end*/ uint32_t start_ip; // start address of leases, in host order uint32_t end_ip; // end of leases, in host order uint32_t max_lease_sec; // maximum lease time (host order) uint32_t min_lease_sec; // minimum lease time a client can request uint32_t max_leases; // maximum number of leases (including reserved addresses) uint32_t auto_time; // how long should dhcpd wait before writing a config file. // if this is zero, it will only write one on SIGUSR1 uint32_t decline_time; // how long an address is reserved if a client returns a // decline message uint32_t conflict_time; // how long an arp conflict offender is leased for uint32_t offer_time; // how long an offered address is reserved uint32_t siaddr_nip; // "next server" bootp option char *lease_file; char *pidfile; char *notify_file; // what to run whenever leases are written char *sname; // bootp server name char *boot_file; // bootp boot file option struct static_lease *static_leases; // List of ip/mac pairs to assign static leases } server_config_t; typedef struct __attribute__((__may_alias__)) server_state_s { uint8_t rqcode; int listensock; dhcp_msg_t rcvd_pkt; uint8_t* rqopt; dhcp_msg_t send_pkt; static_lease *sleases; struct arg_list *dleases; } server_state_t; struct config_keyword { char *keyword; int (*handler)(const char *str, void *var); void *var; char *def; }; static option_val_t options_list[] = { {"lease" , DHCP_NUM32 | 0x33, NULL, 0}, {"subnet" , DHCP_IP | 0x01, NULL, 0}, {"broadcast" , DHCP_IP | 0x1c, NULL, 0}, {"router" , DHCP_IP | 0x03, NULL, 0}, {"ipttl" , DHCP_NUM8 | 0x17, NULL, 0}, {"mtu" , DHCP_NUM16 | 0x1a, NULL, 0}, {"hostname" , DHCP_STRING | 0x0c, NULL, 0}, {"domain" , DHCP_STRING | 0x0f, NULL, 0}, {"search" , DHCP_STRLST | 0x77, NULL, 0}, {"nisdomain" , DHCP_STRING | 0x28, NULL, 0}, {"timezone" , DHCP_NUM32 | 0x02, NULL, 0}, {"tftp" , DHCP_STRING | 0x42, NULL, 0}, {"bootfile" , DHCP_STRING | 0x43, NULL, 0}, {"bootsize" , DHCP_NUM16 | 0x0d, NULL, 0}, {"rootpath" , DHCP_STRING | 0x11, NULL, 0}, {"wpad" , DHCP_STRING | 0xfc, NULL, 0}, {"serverid" , DHCP_IP | 0x36, NULL, 0}, {"message" , DHCP_STRING | 0x38, NULL, 0}, {"vlanid" , DHCP_NUM32 | 0x84, NULL, 0}, {"vlanpriority" , DHCP_NUM32 | 0x85, NULL, 0}, {"dns" , DHCP_IPLIST | 0x06, NULL, 0}, {"wins" , DHCP_IPLIST | 0x2c, NULL, 0}, {"nissrv" , DHCP_IPLIST | 0x29, NULL, 0}, {"ntpsrv" , DHCP_IPLIST | 0x2a, NULL, 0}, {"lprsrv" , DHCP_IPLIST | 0x09, NULL, 0}, {"swapsrv" , DHCP_IP | 0x10, NULL, 0}, {"routes" , DHCP_STCRTS | 0x21, NULL, 0}, {"staticroutes" , DHCP_STCRTS | 0x79, NULL, 0}, {"msstaticroutes" , DHCP_STCRTS | 0xf9, NULL, 0}, }; struct fd_pair { int rd; int wr; }; static server_config_t gconfig; static server_state_t gstate; static uint8_t infomode; static struct fd_pair sigfd; static int constone = 1; // calculate options size. static int dhcp_opt_size(uint8_t *optionptr) { int i = 0; for(;optionptr[i] != 0xff; i++) if(optionptr[i] != 0x00) i += optionptr[i + 1] + 2 -1; return i; } // calculates checksum for dhcp messeges. static uint16_t dhcp_checksum(void *addr, int count) { int32_t sum = 0; uint16_t tmp = 0, *source = (uint16_t *)addr; while (count > 1) { sum += *source++; count -= 2; } if (count > 0) { *(uint8_t*)&tmp = *(uint8_t*)source; sum += tmp; } while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16); return ~sum; } // gets information of INTERFACE and updates IFINDEX, MAC and IP static int get_interface(const char *interface, int *ifindex, uint32_t *oip, uint8_t *mac) { struct ifreq req; struct sockaddr_in *ip; int fd = xsocket(AF_INET, SOCK_RAW, IPPROTO_RAW); req.ifr_addr.sa_family = AF_INET; strncpy(req.ifr_name, interface, IFNAMSIZ); req.ifr_name[IFNAMSIZ-1] = '\0'; xioctl(fd, SIOCGIFFLAGS, &req); if (!(req.ifr_flags & IFF_UP)) return -1; if (oip) { xioctl(fd, SIOCGIFADDR, &req); ip = (struct sockaddr_in*) &req.ifr_addr; dbg("IP %s\n", inet_ntoa(ip->sin_addr)); *oip = ntohl(ip->sin_addr.s_addr); } if (ifindex) { xioctl(fd, SIOCGIFINDEX, &req); dbg("Adapter index %d\n", req.ifr_ifindex); *ifindex = req.ifr_ifindex; } if (mac) { xioctl(fd, SIOCGIFHWADDR, &req); memcpy(mac, req.ifr_hwaddr.sa_data, 6); dbg("MAC %02x:%02x:%02x:%02x:%02x:%02x\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]); } close(fd); return 0; } /* *logs messeges to syslog or console *opening the log is still left with applet. *FIXME: move to more relevent lib. probably libc.c */ static void infomsg(uint8_t infomode, char *s, ...) { int used; char *msg; va_list p, t; if (infomode == LOG_SILENT) return; va_start(p, s); va_copy(t, p); used = vsnprintf(NULL, 0, s, t); used++; va_end(t); msg = xmalloc(used); vsnprintf(msg, used, s, p); va_end(p); if (infomode & LOG_SYSTEM) syslog(LOG_INFO, "%s", msg); if (infomode & LOG_CONSOLE) printf("%s\n", msg); free(msg); } /* * Writes self PID in file PATH * FIXME: libc implementation only writes in /var/run * this is more generic as some implemenation may provide * arguments to write in specific file. as dhcpd does. */ static void write_pid(char *path) { int pidfile = open(path, O_CREAT | O_WRONLY | O_TRUNC, 0666); if (pidfile > 0) { char pidbuf[12]; sprintf(pidbuf, "%u", (unsigned)getpid()); write(pidfile, pidbuf, strlen(pidbuf)); close(pidfile); } } // Generic signal handler real handling is done in main funcrion. static void signal_handler(int sig) { unsigned char ch = sig; if (write(sigfd.wr, &ch, 1) != 1) dbg("can't send signal\n"); } // signal setup for SIGUSR1 SIGTERM static int setup_signal() { if (pipe((int *)&sigfd) < 0) { dbg("signal pipe failed\n"); return -1; } fcntl(sigfd.wr , F_SETFD, FD_CLOEXEC); fcntl(sigfd.rd , F_SETFD, FD_CLOEXEC); int flags = fcntl(sigfd.wr, F_GETFL); fcntl(sigfd.wr, F_SETFL, flags | O_NONBLOCK); signal(SIGUSR1, signal_handler); signal(SIGTERM, signal_handler); return 0; } // String STR to UINT32 conversion strored in VAR static int strtou32(const char *str, void *var) { char *endptr = NULL; int base = 10; errno=0; *((uint32_t*)(var)) = 0; if (str[0]=='0' && (str[1]=='x' || str[1]=='X')) { base = 16; str+=2; } long ret_val = strtol(str, &endptr, base); if (errno) infomsg(infomode, "config : Invalid num %s",str); else if (endptr && (*endptr!='\0'||endptr == str)) infomsg(infomode, "config : Not a valid num %s",str); else *((uint32_t*)(var)) = (uint32_t)ret_val; return 0; } // copy string STR in variable VAR static int strinvar(const char *str, void *var) { char **dest = var; if (*dest) free(*dest); *dest = strdup(str); return 0; } // IP String STR to binary data. static int striptovar(const char *str, void *var) { in_addr_t addr; *((uint32_t*)(var)) = 0; if(!str) { error_msg("config : NULL address string \n"); return -1; } if((addr = inet_addr(str)) == -1) { error_msg("config : wrong address %s \n",str ); return -1; } *((uint32_t*)(var)) = (uint32_t)addr; return 0; } // String to dhcp option conversion static int strtoopt(const char *str, void *var) { char *option, *valstr, *grp, *tp; uint32_t optcode = 0, inf = infomode, convtmp, mask, nip, router; uint16_t flag = 0; int count, size = ARRAY_LEN(options_list); if (!*str) return 0; if (!(option = strtok((char*)str, " \t="))) return -1; infomode = LOG_SILENT; strtou32(option, (uint32_t*)&optcode); infomode = inf; if (optcode > 0 && optcode < 256) { // raw option for (count = 0; count < size; count++) { if ((options_list[count].code & 0X00FF) == optcode) { flag = (options_list[count].code & 0XFF00); break; } } } else { //string option for (count = 0; count < size; count++) { if (!strncmp(options_list[count].key, option, strlen(options_list[count].key))) { flag = (options_list[count].code & 0XFF00); optcode = (options_list[count].code & 0X00FF); break; } } } if (count == size) { infomsg(inf, "config : Obsolete OR Unknown Option : %s", option); return -1; } if (!flag || !optcode) return -1; if (!(valstr = strtok(NULL, " \t"))) { dbg("config : option %s has no value defined.\n", option); return -1; } dbg(" value : %-20s : ", valstr); switch (flag) { case DHCP_NUM32: options_list[count].len = sizeof(uint32_t); options_list[count].val = xmalloc(sizeof(uint32_t)); strtou32(valstr, &convtmp); memcpy(options_list[count].val, &convtmp, sizeof(uint32_t)); break; case DHCP_NUM16: options_list[count].len = sizeof(uint16_t); options_list[count].val = xmalloc(sizeof(uint16_t)); strtou32(valstr, &convtmp); memcpy(options_list[count].val, &convtmp, sizeof(uint16_t)); break; case DHCP_NUM8: options_list[count].len = sizeof(uint8_t); options_list[count].val = xmalloc(sizeof(uint8_t)); strtou32(valstr, &convtmp); memcpy(options_list[count].val, &convtmp, sizeof(uint8_t)); break; case DHCP_IP: options_list[count].len = sizeof(uint32_t); options_list[count].val = xmalloc(sizeof(uint32_t)); striptovar(valstr, options_list[count].val); break; case DHCP_STRING: options_list[count].len = strlen(valstr); options_list[count].val = strdup(valstr); break; case DHCP_IPLIST: while(valstr){ options_list[count].val = xrealloc(options_list[count].val, options_list[count].len + sizeof(uint32_t)); striptovar(valstr, ((uint8_t*)options_list[count].val)+options_list[count].len); options_list[count].len += sizeof(uint32_t); valstr = strtok(NULL," \t"); } break; case DHCP_IPPLST: break; case DHCP_STCRTS: /* Option binary format: * mask [one byte, 0..32] * ip [0..4 bytes depending on mask] * router [4 bytes] * may be repeated * staticroutes 10.0.0.0/8 10.127.0.1, 10.11.12.0/24 10.11.12.1 */ grp = strtok(valstr, ",");; while(grp){ while(*grp == ' ' || *grp == '\t') grp++; tp = strchr(grp, '/'); if (!tp) error_exit("wrong formated static route option"); *tp = '\0'; mask = strtol(++tp, &tp, 10); if (striptovar(grp, (uint8_t*)&nip)<0) error_exit("wrong formated static route option"); while(*tp == ' ' || *tp == '\t' || *tp == '-') tp++; if (striptovar(tp, (uint8_t*)&router)<0) error_exit("wrong formated static route option"); options_list[count].val = xrealloc(options_list[count].val, options_list[count].len + 1 + mask/8 + 4); memcpy(((uint8_t*)options_list[count].val)+options_list[count].len, &mask, 1); options_list[count].len += 1; memcpy(((uint8_t*)options_list[count].val)+options_list[count].len, &nip, mask/8); options_list[count].len += mask/8; memcpy(((uint8_t*)options_list[count].val)+options_list[count].len, &router, 4); options_list[count].len += 4; tp = NULL; grp = strtok(NULL, ","); } break; } return 0; } // Reads Static leases from STR and updates inner structures. static int get_staticlease(const char *str, void *var) { struct static_lease_s *sltmp; char *tkmac, *tkip; int count; if (!*str) return 0; if (!(tkmac = strtok((char*)str, " \t"))) { infomsg(infomode, "config : static lease : mac not found"); return 0; } if (!(tkip = strtok(NULL, " \t"))) { infomsg(infomode, "config : static lease : no ip bind to mac %s", tkmac); return 0; } sltmp = xzalloc(sizeof(struct static_lease_s)); for (count = 0; count < 6; count++, tkmac++) { errno = 0; sltmp->mac[count] = strtol(tkmac, &tkmac, 16); if (sltmp->mac[count]>255 || sltmp->mac[count]<0 || (*tkmac && *tkmac!=':') || errno) { infomsg(infomode, "config : static lease : mac address wrong format"); free(sltmp); return 0; } } striptovar(tkip, &sltmp->nip); sltmp->next = gstate.sleases; gstate.sleases = sltmp; return 0; } static struct config_keyword keywords[] = { // keyword handler variable address default {"start" , striptovar , (void*)&gconfig.start_ip , "192.168.0.20"}, {"end" , striptovar , (void*)&gconfig.end_ip , "192.168.0.254"}, {"interface" , strinvar , (void*)&gconfig.interface , "eth0"}, {"port" , strtou32 , (void*)&gconfig.port , "67"}, {"min_lease" , strtou32 , (void*)&gconfig.min_lease_sec, "60"}, {"max_leases" , strtou32 , (void*)&gconfig.max_leases , "235"}, {"auto_time" , strtou32 , (void*)&gconfig.auto_time , "7200"}, {"decline_time" , strtou32 , (void*)&gconfig.decline_time , "3600"}, {"conflict_time", strtou32 , (void*)&gconfig.conflict_time, "3600"}, {"offer_time" , strtou32 , (void*)&gconfig.offer_time , "60"}, {"lease_file" , strinvar , (void*)&gconfig.lease_file , "/var/lib/misc/dhcpd.leases"}, //LEASES_FILE {"pidfile" , strinvar , (void*)&gconfig.pidfile , "/var/run/dhcpd.pid"}, //DPID_FILE {"siaddr" , striptovar , (void*)&gconfig.siaddr_nip , "0.0.0.0"}, {"option" , strtoopt , (void*)&gconfig.options , ""}, {"opt" , strtoopt , (void*)&gconfig.options , ""}, {"notify_file" , strinvar , (void*)&gconfig.notify_file , ""}, {"sname" , strinvar , (void*)&gconfig.sname , ""}, {"boot_file" , strinvar , (void*)&gconfig.boot_file , ""}, {"static_lease" , get_staticlease , (void*)&gconfig.static_leases, ""}, }; // Parses the server config file and updates the global server config accordingly. static int parse_server_config(char *config_file, struct config_keyword *confkey) { FILE *fs = NULL; char *confline_temp = NULL,*confline = NULL, *tk = NULL, *tokens[2] = {NULL, NULL}; int len, linelen, tcount, count, size = ARRAY_LEN(keywords); for (count = 0; count < size; count++) if (confkey[count].handler) confkey[count].handler(confkey[count].def, confkey[count].var); if (!(fs = fopen(config_file, "r"))) perror_msg("%s", config_file); for (len = 0, linelen = 0; fs;) { len = getline(&confline_temp, (size_t*) &linelen, fs); confline = confline_temp; if (len <= 0) break; for (; *confline == ' '; confline++, len--); if ((confline[0] == '#') || (confline[0] == '\n')) goto free_conf_continue; tk = strchr(confline, '#'); if (tk) { for (; *(tk-1)==' ' || *(tk-1)=='\t'; tk--); *tk = '\0'; } tk = strchr(confline, '\n'); if (tk) { for (; *(tk-1)==' ' || *(tk-1)=='\t'; tk--); *tk = '\0'; } for (tcount=0, tk=strtok(confline, " \t"); tk && (tcount < 2); tcount++, tk=strtok(NULL,(tcount==1)?"":" \t")) { while ((*tk == '\t') || (*tk == ' ')) tk++; tokens[tcount] = xstrdup(tk); } if (tcount<=1) goto free_tk0_continue; for (count = 0; count < size; count++) { if (!strcmp(confkey[count].keyword,tokens[0])) { dbg("got config : %15s : ", confkey[count].keyword); if (confkey[count].handler(tokens[1], confkey[count].var) == 0) dbg("%s \n", tokens[1]); break; } } if (tokens[1]) { free(tokens[1]); tokens[1] = NULL; } free_tk0_continue: if (tokens[0]) { free(tokens[0]); tokens[0] = NULL; } free_conf_continue: free(confline_temp); confline_temp = NULL; } if (fs) fclose(fs); return 0; } // opens UDP socket for listen static int open_listensock(void) { struct sockaddr_in addr; struct ifreq ifr; if (gstate.listensock > 0) close(gstate.listensock); dbg("Opening listen socket on *:%d %s\n", gconfig.port, gconfig.interface); gstate.listensock = xsocket(PF_INET, SOCK_DGRAM, IPPROTO_UDP); setsockopt(gstate.listensock, SOL_SOCKET, SO_REUSEADDR, &constone, sizeof(constone)); if (setsockopt(gstate.listensock, SOL_SOCKET, SO_BROADCAST, &constone, sizeof(constone)) == -1) { dbg("OPEN : brodcast ioctl failed.\n"); close(gstate.listensock); return -1; } memset(&ifr, 0, sizeof(ifr)); strncpy(ifr.ifr_name, gconfig.interface, IFNAMSIZ); ifr.ifr_name[IFNAMSIZ -1] = '\0'; setsockopt(gstate.listensock, SOL_SOCKET, SO_BINDTODEVICE, &ifr, sizeof(ifr)); memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_port = (flag_chk(FLAG_P))?htons(TT.port):htons(67); //SERVER_PORT addr.sin_addr.s_addr = INADDR_ANY ; if (bind(gstate.listensock, (struct sockaddr *) &addr, sizeof(addr))) { close(gstate.listensock); perror_exit("bind failed"); } dbg("OPEN : success\n"); return 0; } // Sends data through raw socket. static int send_packet(uint8_t broadcast) { struct sockaddr_ll dest_sll; dhcp_raw_t packet; unsigned padding; int fd, result = -1; uint8_t bmacaddr[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff}; memset(&packet, 0, sizeof(dhcp_raw_t)); memcpy(&packet.dhcp, &gstate.send_pkt, sizeof(dhcp_msg_t)); if ((fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP))) < 0) { dbg("SEND : socket failed\n"); return -1; } memset(&dest_sll, 0, sizeof(dest_sll)); dest_sll.sll_family = AF_PACKET; dest_sll.sll_protocol = htons(ETH_P_IP); dest_sll.sll_ifindex = gconfig.ifindex; dest_sll.sll_halen = 6; memcpy(dest_sll.sll_addr, (broadcast)?bmacaddr:gstate.rcvd_pkt.chaddr , 6); if (bind(fd, (struct sockaddr *) &dest_sll, sizeof(dest_sll)) < 0) { dbg("SEND : bind failed\n"); close(fd); return -1; } padding = 308 - 1 - dhcp_opt_size(gstate.send_pkt.options); packet.iph.protocol = IPPROTO_UDP; packet.iph.saddr = gconfig.server_nip; packet.iph.daddr = (broadcast || (gstate.rcvd_pkt.ciaddr == 0))?INADDR_BROADCAST:gstate.rcvd_pkt.ciaddr; packet.udph.source = htons(67);//SERVER_PORT packet.udph.dest = htons(68); //CLIENT_PORT packet.udph.len = htons(sizeof(dhcp_raw_t) - sizeof(struct iphdr) - padding); packet.iph.tot_len = packet.udph.len; packet.udph.check = dhcp_checksum(&packet, sizeof(dhcp_raw_t) - padding); packet.iph.tot_len = htons(sizeof(dhcp_raw_t) - padding); packet.iph.ihl = sizeof(packet.iph) >> 2; packet.iph.version = IPVERSION; packet.iph.ttl = IPDEFTTL; packet.iph.check = dhcp_checksum(&packet.iph, sizeof(packet.iph)); result = sendto(fd, &packet, sizeof(dhcp_raw_t) - padding, 0, (struct sockaddr *) &dest_sll, sizeof(dest_sll)); dbg("sendto %d\n", result); close(fd); if (result < 0) dbg("PACKET send error\n"); return result; } // Reads from UDP socket static int read_packet(void) { int ret; memset(&gstate.rcvd_pkt, 0, sizeof(dhcp_msg_t)); ret = read(gstate.listensock, &gstate.rcvd_pkt, sizeof(dhcp_msg_t)); if (ret < 0) { dbg("Packet read error, ignoring. \n"); return ret; // returns -1 } if (gstate.rcvd_pkt.cookie != htonl(DHCP_MAGIC)) { dbg("Packet with bad magic, ignoring. \n"); return -2; } if (gstate.rcvd_pkt.op != 1) { //BOOTPREQUEST dbg("Not a BOOT REQUEST ignoring. \n"); return -2; } if (gstate.rcvd_pkt.hlen != 6) { dbg("hlen != 6 ignoring. \n"); return -2; } dbg("Received a packet. Size : %d \n", ret); return ret; } // Preapres a dhcp packet with defaults and configs static uint8_t* prepare_send_pkt(void) { memset((void*)&gstate.send_pkt, 0, sizeof(gstate.send_pkt)); gstate.send_pkt.op = 2; //BOOTPREPLY gstate.send_pkt.htype = 1; gstate.send_pkt.hlen = 6; gstate.send_pkt.xid = gstate.rcvd_pkt.xid; gstate.send_pkt.cookie = htonl(DHCP_MAGIC); gstate.send_pkt.nsiaddr = gconfig.server_nip; memcpy(gstate.send_pkt.chaddr, gstate.rcvd_pkt.chaddr, 16); gstate.send_pkt.options[0] = DHCP_OPT_END; return gstate.send_pkt.options; } // Sets a option value in dhcp packet's option field static uint8_t* set_optval(uint8_t *optptr, uint16_t opt, void *var, size_t len) { while (*optptr != DHCP_OPT_END) optptr++; *optptr++ = (uint8_t)(opt & 0x00FF); *optptr++ = (uint8_t) len; memcpy(optptr, var, len); optptr += len; *optptr = DHCP_OPT_END; return optptr; } // Gets a option value from dhcp packet's option field static uint8_t* get_optval(uint8_t *optptr, uint16_t opt, void *var) { size_t len; uint8_t overloaded = 0; while (1) { while (*optptr == DHCP_OPT_PADDING) optptr++; if ((*optptr & 0x00FF) == DHCP_OPT_END) break; if ((*optptr & 0x00FF) == DHCP_OPT_OPTION_OVERLOAD) { overloaded = optptr[2]; optptr += optptr[1] + 2; } len = optptr[1]; if (*optptr == (opt & 0x00FF)) switch (opt & 0xFF00) { case DHCP_NUM32: // FALLTHROUGH case DHCP_IP: memcpy(var, optptr+2, sizeof(uint32_t)); optptr += len + 2; return optptr; break; case DHCP_NUM16: memcpy(var, optptr+2, sizeof(uint16_t)); optptr += len + 2; return optptr; break; case DHCP_NUM8: memcpy(var, optptr+2, sizeof(uint8_t)); optptr += len + 2; return optptr; break; case DHCP_STRING: var = xstrndup((char*) optptr, len); optptr += len + 2; return optptr; break; } optptr += len + 2; } if ((overloaded == 1) | (overloaded == 3)) get_optval((uint8_t*)&gstate.rcvd_pkt.file, opt, var); if ((overloaded == 2) | (overloaded == 3)) get_optval((uint8_t*)&gstate.rcvd_pkt.sname, opt, var); return optptr; } // Retrives Requested Parameter list from dhcp req packet. static uint8_t get_reqparam(uint8_t **list) { uint8_t len, *optptr; if(*list) free(*list); for (optptr = gstate.rcvd_pkt.options; *optptr && *optptr!=((DHCP_OPT_PARAM_REQ) & 0x00FF); optptr+=optptr[1]+2); len = *++optptr; *list = xzalloc(len+1); memcpy(*list, ++optptr, len); return len; } // Sets values of req param in dhcp offer packet. static uint8_t* set_reqparam(uint8_t *optptr, uint8_t *list) { uint8_t reqcode; int count, size = ARRAY_LEN(options_list); while (*list) { reqcode = *list++; for (count = 0; count < size; count++) { if ((options_list[count].code & 0X00FF)==reqcode) { if (!(options_list[count].len) || !(options_list[count].val)) break; for (; *optptr && *optptr!=DHCP_OPT_END; optptr+=optptr[1]+2); *optptr++ = (uint8_t) (options_list[count].code & 0x00FF); *optptr++ = (uint8_t) options_list[count].len; memcpy(optptr, options_list[count].val, options_list[count].len); optptr += options_list[count].len; *optptr = DHCP_OPT_END; break; } } } return optptr; } static void run_notify(char **argv) { struct stat sts; volatile int error = 0; pid_t pid; if (stat(argv[0], &sts) == -1 && errno == ENOENT) { infomsg(infomode, "notify file: %s : not exist.", argv[0]); return; } fflush(NULL); pid = vfork(); if (pid < 0) { dbg("Fork failed.\n"); return; } if (!pid) { execvp(argv[0], argv); error = errno; _exit(111); } if (error) { waitpid(pid, NULL, 0); errno = error; } dbg("script complete.\n"); } static int write_leasefile(void) { int fd; uint32_t curr, tmp_time; int64_t timestamp; struct arg_list *listdls = gstate.dleases; dyn_lease *dls; if ((fd = open(gconfig.lease_file, O_WRONLY | O_CREAT | O_TRUNC)) < 0) { perror_msg("can't open %s ", gconfig.lease_file); return fd; } curr = timestamp = time(NULL); timestamp = SWAP_BE64(timestamp); writeall(fd, ×tamp, sizeof(timestamp)); while (listdls) { dls = (dyn_lease*)listdls->arg; tmp_time = dls->expires; dls->expires -= curr; if ((int32_t) dls->expires < 0) goto skip; dls->expires = htonl(dls->expires); writeall(fd, dls, sizeof(dyn_lease)); skip: dls->expires = tmp_time; listdls = listdls->next; } close(fd); if (gconfig.notify_file) { char *argv[3]; argv[0] = gconfig.notify_file; argv[1] = gconfig.lease_file; argv[2] = NULL; run_notify(argv); } return 0; } // Update max lease time from options. static void set_maxlease(void) { int count, size = ARRAY_LEN(options_list); for (count = 0; count < size; count++) if (options_list[count].val && options_list[count].code == (DHCP_OPT_LEASE_TIME)) { gconfig.max_lease_sec = *((uint32_t*)options_list[count].val); break; } if (!gconfig.max_lease_sec) gconfig.max_lease_sec = (60*60*24*10);// DEFAULT_LEASE_TIME; } // Returns lease time for client. static uint32_t get_lease(uint32_t req_exp) { uint32_t now = time(NULL); req_exp = req_exp - now; if ((req_exp <= 0) || (req_exp > gconfig.max_lease_sec)) return gconfig.max_lease_sec; if (req_exp < gconfig.min_lease_sec) return gconfig.min_lease_sec; return req_exp; } // Verify ip NIP in current leases ( assigned or not) static int verifyip_in_lease(uint32_t nip, uint8_t mac[6]) { static_lease *sls; struct arg_list *listdls; for (listdls = gstate.dleases; listdls; listdls = listdls->next) { if (((dyn_lease*) listdls->arg)->lease_nip == nip) { if (((int32_t)(((dyn_lease*) listdls->arg)->expires) - time(NULL)) < 0) return 0; return -1; } if (!memcmp(((dyn_lease*) listdls->arg)->lease_mac, mac, 6)) return -1; } for (sls = gstate.sleases; sls; sls = sls->next) if (sls->nip == nip) return -2; if ((ntohl(nip) < gconfig.start_ip) || (ntohl(nip) > gconfig.end_ip)) return -3; return 0; } // add ip assigned_nip to dynamic lease. static int addip_to_lease(uint32_t assigned_nip, uint8_t mac[6], uint32_t *req_exp, char *hostname, uint8_t update) { dyn_lease *dls; struct arg_list *listdls = gstate.dleases; uint32_t now = time(NULL); while (listdls) { if (!memcmp(((dyn_lease*) listdls->arg)->lease_mac, mac, 6)) { if (update) *req_exp = get_lease(*req_exp + ((dyn_lease*) listdls->arg)->expires); ((dyn_lease*) listdls->arg)->expires = *req_exp + now; return 0; } listdls = listdls->next; } dls = xzalloc(sizeof(dyn_lease)); memcpy(dls->lease_mac, mac, 6); dls->lease_nip = assigned_nip; if (hostname) memcpy(dls->hostname, hostname, 20); if (update) *req_exp = get_lease(*req_exp + now); dls->expires = *req_exp + now; listdls = xzalloc(sizeof(struct arg_list)); listdls->next = gstate.dleases; listdls->arg = (char*)dls; gstate.dleases = listdls; return 0; } // delete ip assigned_nip from dynamic lease. static int delip_from_lease(uint32_t assigned_nip, uint8_t mac[6], uint32_t del_time) { struct arg_list *listdls = gstate.dleases; while (listdls) { if (!memcmp(((dyn_lease*) listdls->arg)->lease_mac, mac, 6)) { ((dyn_lease*) listdls->arg)->expires = del_time + time(NULL); return 0; } listdls = listdls->next; } return -1; } // returns a IP from static, dynamic leases or free ip pool, 0 otherwise. static uint32_t getip_from_pool(uint32_t req_nip, uint8_t mac[6], uint32_t *req_exp, char *hostname) { uint32_t nip = 0; static_lease *sls = gstate.sleases; struct arg_list *listdls = gstate.dleases, *tmp = NULL; if (req_nip && (!verifyip_in_lease(req_nip, mac))) nip = req_nip; if (!nip) { while (listdls) { if (!memcmp(((dyn_lease*)listdls->arg)->lease_mac, mac, 6)) { nip = ((dyn_lease*)listdls->arg)->lease_nip; if (tmp) tmp->next = listdls->next; else gstate.dleases = listdls->next; free(listdls->arg); free(listdls); if (verifyip_in_lease(nip, mac) < 0) nip = 0; break; } tmp = listdls; listdls = listdls->next; } } if (!nip) { while (sls) { if (memcmp(sls->mac, mac, 6) == 0) { nip = sls->nip; break; } sls = sls->next; } } if (!nip) { for (nip = htonl(gconfig.start_ip); ntohl(nip) <= gconfig.end_ip; ) { if (!verifyip_in_lease(nip, mac)) break; nip = ntohl(nip); nip = htonl(++nip); } if (ntohl(nip) > gconfig.end_ip) { nip = 0; infomsg(infomode, "can't find free IP in IP Pool."); } } if (nip) addip_to_lease(nip, mac, req_exp, hostname, 1); return nip; } static int read_leasefile(void) { uint32_t passed, ip; int32_t tmp_time; int64_t timestamp; dyn_lease *dls; int ret = -1, fd = open(gconfig.lease_file, O_RDONLY); if (fd < 0) return fd; dls = xzalloc(sizeof(dyn_lease)); if (read(fd, ×tamp, sizeof(timestamp)) != sizeof(timestamp)) goto error_exit; timestamp = SWAP_BE64(timestamp); passed = time(NULL) - timestamp; if ((uint64_t)passed > 12 * 60 * 60) goto error_exit; while (read(fd, dls, sizeof(dyn_lease)) == sizeof(dyn_lease)) { ip = ntohl(dls->lease_nip); if (ip >= gconfig.start_ip && ip <= gconfig.end_ip) { tmp_time = ntohl(dls->expires) - passed; if (tmp_time < 0) continue; addip_to_lease(dls->lease_nip, dls->lease_mac, (uint32_t*)&tmp_time, dls->hostname, 0); } } ret = 0; error_exit: free(dls); close(fd); return ret; } void dhcpd_main(void) { struct timeval tv; int retval; uint8_t *optptr, msgtype = 0; uint32_t waited = 0, serverid = 0, requested_nip = 0; uint32_t reqested_lease = 0, ip_pool_size = 0; char *hstname = NULL; fd_set rfds; infomode = LOG_CONSOLE; if (!(flag_chk(FLAG_f))) { daemon(0,0); infomode = LOG_SILENT; } if (flag_chk(FLAG_S)) { openlog("UDHCPD :", LOG_PID, LOG_DAEMON); infomode |= LOG_SYSTEM; } setlinebuf(stdout); parse_server_config((toys.optc==1)?toys.optargs[0]:"/etc/dhcpd.conf", keywords); //DHCPD_CONF_FILE infomsg(infomode, "toybox dhcpd started"); gconfig.start_ip = ntohl(gconfig.start_ip); gconfig.end_ip = ntohl(gconfig.end_ip); ip_pool_size = gconfig.end_ip - gconfig.start_ip + 1; if (gconfig.max_leases > ip_pool_size) { error_msg("max_leases=%u is too big, setting to %u", (unsigned) gconfig.max_leases, ip_pool_size); gconfig.max_leases = ip_pool_size; } write_pid(gconfig.pidfile); set_maxlease(); read_leasefile(); if (get_interface(gconfig.interface, &gconfig.ifindex, &gconfig.server_nip, gconfig.server_mac)<0) perror_exit("Failed to get interface %s", gconfig.interface); gconfig.server_nip = htonl(gconfig.server_nip); setup_signal(); open_listensock(); fcntl(gstate.listensock, F_SETFD, FD_CLOEXEC); for (;;) { uint32_t timestmp = time(NULL); FD_ZERO(&rfds); FD_SET(gstate.listensock, &rfds); FD_SET(sigfd.rd, &rfds); tv.tv_sec = gconfig.auto_time - waited; tv.tv_usec = 0; retval = 0; serverid = 0; msgtype = 0; int maxfd = (sigfd.rd > gstate.listensock)? sigfd.rd : gstate.listensock; dbg("select waiting ....\n"); retval = select(maxfd + 1, &rfds, NULL, NULL, (gconfig.auto_time?&tv:NULL)); if (retval < 0) { if (errno == EINTR) { waited += (unsigned) time(NULL) - timestmp; continue; } dbg("Error in select wait again...\n"); continue; } if (!retval) { // Timed out dbg("select wait Timed Out...\n"); waited = 0; write_leasefile(); if (get_interface(gconfig.interface, &gconfig.ifindex, &gconfig.server_nip, gconfig.server_mac)<0) perror_exit("Interface lost %s\n", gconfig.interface); gconfig.server_nip = htonl(gconfig.server_nip); continue; } if (FD_ISSET(sigfd.rd, &rfds)) { // Some Activity on RDFDs : is signal unsigned char sig; if (read(sigfd.rd, &sig, 1) != 1) { dbg("signal read failed.\n"); continue; } switch (sig) { case SIGUSR1: infomsg(infomode, "Received SIGUSR1"); write_leasefile(); continue; case SIGTERM: infomsg(infomode, "Received SIGTERM"); write_leasefile(); unlink(gconfig.pidfile); exit(0); break; default: break; } } if (FD_ISSET(gstate.listensock, &rfds)) { // Some Activity on RDFDs : is socket dbg("select listen sock read\n"); if (read_packet() < 0) { open_listensock(); continue; } waited += time(NULL) - timestmp; get_optval((uint8_t*)&gstate.rcvd_pkt.options, DHCP_OPT_MESSAGE_TYPE, &gstate.rqcode); if (gstate.rqcode == 0 || gstate.rqcode < DHCPDISCOVER || gstate.rqcode > DHCPINFORM) { dbg("no or bad message type option, ignoring packet.\n"); continue; } get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_SERVER_ID, &serverid); if (serverid && (serverid != gconfig.server_nip)) { dbg("server ID doesn't match, ignoring packet.\n"); continue; } switch (gstate.rqcode) { case DHCPDISCOVER: msgtype = DHCPOFFER; dbg("Message Type : DHCPDISCOVER\n"); get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_REQUESTED_IP, &requested_nip); get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_HOST_NAME, &hstname); reqested_lease = gconfig.offer_time; get_reqparam(&gstate.rqopt); optptr = prepare_send_pkt(); gstate.send_pkt.yiaddr = getip_from_pool(requested_nip, gstate.rcvd_pkt.chaddr, &reqested_lease, hstname); if(!gstate.send_pkt.yiaddr){ msgtype = DHCPNAK; optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1); send_packet(1); break; } get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_LEASE_TIME, &reqested_lease); reqested_lease = htonl(get_lease(reqested_lease + time(NULL))); optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1); optptr = set_optval(optptr, DHCP_OPT_SERVER_ID, &gconfig.server_nip, 4); optptr = set_optval(optptr, DHCP_OPT_LEASE_TIME, &reqested_lease, 4); optptr = set_reqparam(optptr, gstate.rqopt); send_packet(1); break; case DHCPREQUEST: msgtype = DHCPACK; dbg("Message Type : DHCPREQUEST\n"); optptr = prepare_send_pkt(); get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_REQUESTED_IP, &requested_nip); get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_LEASE_TIME, &reqested_lease); get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_HOST_NAME, &hstname); gstate.send_pkt.yiaddr = getip_from_pool(requested_nip, gstate.rcvd_pkt.chaddr, &reqested_lease, hstname); if (!serverid) reqested_lease = gconfig.max_lease_sec; if (!gstate.send_pkt.yiaddr) { msgtype = DHCPNAK; optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1); send_packet(1); break; } optptr = set_optval(optptr, DHCP_OPT_MESSAGE_TYPE, &msgtype, 1); optptr = set_optval(optptr, DHCP_OPT_SERVER_ID, &gconfig.server_nip, 4); reqested_lease = htonl(reqested_lease); optptr = set_optval(optptr, DHCP_OPT_LEASE_TIME, &reqested_lease, 4); send_packet(1); write_leasefile(); break; case DHCPDECLINE:// FALL THROUGH case DHCPRELEASE: dbg("Message Type : DHCPDECLINE or DHCPRELEASE \n"); get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_SERVER_ID, &serverid); if (serverid != gconfig.server_nip) break; get_optval((uint8_t*) &gstate.rcvd_pkt.options, DHCP_OPT_REQUESTED_IP, &requested_nip); delip_from_lease(requested_nip, gstate.rcvd_pkt.chaddr, (gstate.rqcode==DHCPRELEASE)?0:gconfig.decline_time); break; default: dbg("Message Type : %u\n", gstate.rqcode); break; } } } }