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/*
* (C) 2013-2014 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"
#include "version.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(s_netaddress.s_addr) < 2) {
fprintf(stderr, "We do not have addresses to serve, need a netmask with 30 bit minimum.\n");
goto out;
}
s_minhost.s_addr = htonl(ntohl(s_netaddress.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 opening config template for reading.\n");
goto out;
}
fseek(configfile, 0, SEEK_END);
fsize = ftell(configfile);
fseek(configfile, 0, SEEK_SET);
config = malloc(fsize + 1);
if ((fread(config, fsize, 1, configfile)) != 1) {
fprintf(stderr, "Failed reading config template.\n");
goto out;
}
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", "-d", "-q", "-4", "-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, link down 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:
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