diff options
Diffstat (limited to 'dyndhcpd.c')
| -rw-r--r-- | dyndhcpd.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/dyndhcpd.c b/dyndhcpd.c new file mode 100644 index 0000000..7316f5c --- /dev/null +++ b/dyndhcpd.c @@ -0,0 +1,244 @@ +/* + * (C) 2013 by Christian Hesse <mail@eworm.de> + * + * This software may be used and distributed according to the terms + * of the GNU General Public License, incorporated herein by reference. + * + * This is an example code skeleton provided by vim-skeleton. + */ + +#include <arpa/inet.h> +#include <sys/socket.h> +#include <net/if.h> +#include <netdb.h> +#include <ifaddrs.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> + +#include "config.h" + +/*** str_replace ***/ +char * str_replace(char * original, const char * pattern, const char * replacement) { + size_t const replen = strlen(replacement); + size_t const patlen = strlen(pattern); + size_t const orilen = strlen(original); + + size_t patcnt = 0; + const char * oriptr; + const char * patloc; + + /* find how many times the pattern occurs in the original string */ + for (oriptr = original; (patloc = strstr(oriptr, pattern)); oriptr = patloc + patlen) + patcnt++; + + /* allocate memory for the new string */ + size_t const retlen = orilen + patcnt * (replen - patlen); + char * const returned = (char *) malloc(sizeof(char) * (retlen + 1)); + + if (returned != NULL) { + /* copy the original string, + * replacing all the instances of the pattern */ + char * retptr = returned; + for (oriptr = original; (patloc = strstr(oriptr, pattern)); oriptr = patloc + patlen) { + size_t const skplen = patloc - oriptr; + /* copy the section until the occurence of the pattern */ + strncpy(retptr, oriptr, skplen); + retptr += skplen; + /* copy the replacement */ + strncpy(retptr, replacement, replen); + retptr += replen; + } + /* copy the rest of the string */ + strcpy(retptr, oriptr); + free(original); + return returned; + } + return NULL; +} + +/*** main ***/ +int main(int argc, char ** argv) { + int i, rc = EXIT_FAILURE; + + struct ifaddrs *ifaddr = NULL, *ifa; + struct sockaddr_in * s4; + struct in_addr * v_host, * v_mask; + struct in_addr s_broadcast, s_netaddress, s_minhost, s_maxhost; + char c_address[INET_ADDRSTRLEN], c_netmask[INET_ADDRSTRLEN], c_netaddress[INET_ADDRSTRLEN], c_broadcast[INET_ADDRSTRLEN], c_minhost[INET_ADDRSTRLEN], c_maxhost[INET_ADDRSTRLEN]; + char * interface = NULL; + + char hostname[254]; + char * domainname; + struct hostent *hp; + + size_t fsize; + char * config = NULL; + char * filename = NULL; + FILE * configfile; + + printf("Starting dyndhcpd/" VERSION " (compiled: " __DATE__ ", " __TIME__ ")\n"); + + for (i = 1; i < argc; i++) { + switch ((int)argv[i][0]) { + case '-': + switch ((int)argv[i][1]) { + case 'h': + fprintf(stderr, "usage: %s [-h] [-iINTERFACE]\n", argv[0]); + return EXIT_SUCCESS; + case 'i': + interface = argv[i] + 2; + if (strlen(interface) == 0) { + fprintf(stderr, "No interface given!\n"); + return EXIT_FAILURE; + } + break; + default: + fprintf(stderr, "unknown option: '%s'\n", argv[i]); + return EXIT_FAILURE; + } + break; + default: + fprintf(stderr, "unknown command line argument: '%s'\n", argv[i]); + return EXIT_FAILURE; + } + } + + if (getuid() > 0) { + fprintf(stderr, "You need to be root!\n"); + goto out; + } + + gethostname(hostname, 254); + hp = gethostbyname(hostname); + if ((domainname = strchr(hp->h_name, '.')) != NULL) + domainname++; + else { + fprintf(stderr, "Could not get domainname, using '" FALLBACKDOMAIN "\n"); + domainname = FALLBACKDOMAIN; + } + + if (interface == NULL) { + fprintf(stderr, "No interface given!\n"); + return EXIT_FAILURE; + } + + if (getifaddrs(&ifaddr) == -1) { + fprintf(stderr, "getifaddrs() failed.\n"); + return EXIT_FAILURE; + } + + for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) { + if (strcmp(interface, ifa->ifa_name) != 0) + continue; + if (ifa->ifa_addr == NULL) + continue; + if (!(ifa->ifa_flags & IFF_UP)) + continue; + if (ifa->ifa_addr->sa_family != AF_INET) + continue; + + s4 = (struct sockaddr_in *)ifa->ifa_addr; + v_host = &s4->sin_addr; + + if (!inet_ntop(ifa->ifa_addr->sa_family, v_host, c_address, INET_ADDRSTRLEN)) + fprintf(stderr, "%s: inet_ntop failed!\n", ifa->ifa_name); + + s4 = (struct sockaddr_in *)ifa->ifa_netmask; + v_mask = &s4->sin_addr; + + if (!inet_ntop(ifa->ifa_netmask->sa_family, v_mask, c_netmask, INET_ADDRSTRLEN)) + fprintf(stderr, "%s: inet_ntop failed!\n", ifa->ifa_name); + + s_broadcast.s_addr = v_host->s_addr |~ v_mask->s_addr; + s_netaddress.s_addr = v_host->s_addr & v_mask->s_addr; + + if (ntohl(s_broadcast.s_addr) - ntohl(v_host->s_addr) < ntohl(v_host->s_addr) - ntohl(s_netaddress.s_addr)) { + s_minhost.s_addr = htonl(ntohl(s_netaddress.s_addr) + 1); + s_maxhost.s_addr = htonl(ntohl(v_host->s_addr) - 1); + } else { + s_minhost.s_addr = htonl(ntohl(v_host->s_addr) + 1); + s_maxhost.s_addr = htonl(ntohl(s_broadcast.s_addr) - 1); + } + + if (inet_ntop(AF_INET, &s_broadcast, c_broadcast, INET_ADDRSTRLEN) != NULL && + inet_ntop(AF_INET, &s_netaddress, c_netaddress, INET_ADDRSTRLEN) != NULL && + inet_ntop(AF_INET, &s_minhost, c_minhost, INET_ADDRSTRLEN) != NULL && + inet_ntop(AF_INET, &s_maxhost, c_maxhost, INET_ADDRSTRLEN) != NULL) { + printf("Interface: %s\n" + "Domain: %s\n" + "Host Address: %s\n" + "Network Address: %s\n" + "Broadcast: %s\n" + "Netmask: %s\n" + "Hosts: %s - %s\n", interface, domainname, c_address, c_netaddress, c_broadcast, c_netmask, c_minhost, c_maxhost); + + + /* read the template */ + if ((configfile = fopen(CONFIG_TEMPLATE, "r")) == NULL) { + fprintf(stderr, "Failed reading config template.\n"); + goto out; + } + fseek(configfile, 0, SEEK_END); + fsize = ftell(configfile); + fseek(configfile, 0, SEEK_SET); + + config = malloc(fsize + 1); + fread(config, fsize, 1, configfile); + fclose(configfile); + config[fsize] = 0; + + if ((config = str_replace(config, "__INTERFACE__", interface)) == NULL) + goto out; + if ((config = str_replace(config, "__VERSION__", VERSION)) == NULL) + goto out; + if ((config = str_replace(config, "__DOMAINNAME__", domainname)) == NULL) + goto out; + if ((config = str_replace(config, "__ADDRESS__", c_address)) == NULL) + goto out; + if ((config = str_replace(config, "__NETADDRESS__", c_netaddress)) == NULL) + goto out; + if ((config = str_replace(config, "__BROADCAST__", c_broadcast)) == NULL) + goto out; + if ((config = str_replace(config, "__NETMASK__", c_netmask)) == NULL) + goto out; + if ((config = str_replace(config, "__MINHOST__", c_minhost)) == NULL) + goto out; + if ((config = str_replace(config, "__MAXHOST__", c_maxhost)) == NULL) + goto out; + + filename = malloc(strlen(CONFIG_OUTPUT) + strlen(interface) + 1); + sprintf(filename, CONFIG_OUTPUT, interface); + if ((configfile = fopen(filename, "w")) == NULL) { + fprintf(stderr, "Failed opening config file for writing.\n"); + goto out; + } + fputs(config, configfile); + fclose(configfile); + + execlp("/usr/bin/dhcpd", "dhcpd", "-f", "-4", "-q", "-cf", filename, interface, NULL); + + rc = EXIT_SUCCESS; + goto out; + } else { + fprintf(stderr, "Failed converting number to string\n"); + goto out; + } + + } + + fprintf(stderr, "Interface not found or no address.\n"); + +out: + if (filename != NULL) + free(filename); + if (config != NULL) + free(config); + if (ifaddr != NULL) + freeifaddrs(ifaddr); + + return rc; +} + +// vim: set syntax=c: |