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/*
* (C) 2013-2015 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.
*/
#include "dyndhcpd.h"
const static char optstring[] = "c:hi:v";
const static struct option options_long[] = {
/* name has_arg flag val */
{ "config", required_argument, NULL, 'c' },
{ "help", no_argument, NULL, 'h' },
{ "interface", required_argument, NULL, 'i' },
{ "verbose", no_argument, NULL, 'v' },
{ 0, 0, 0, 0 }
};
/*** main ***/
int main(int argc, char ** argv) {
int i, rc = EXIT_FAILURE, verbose = 0;
const char * tmp;
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;
char * template = NULL;
FILE * templatefile;
const char * templatefilename = NULL;
char * config = NULL;
FILE * configfile;
char * configfilename = NULL;
size_t fsize, length = 0;
char * pidfile = NULL, * leasesfile = NULL;
printf("Starting dyndhcpd/" VERSION " (compiled: " __DATE__ ", " __TIME__ ")\n");
/* get command line options */
while ((i = getopt_long(argc, argv, optstring, options_long, NULL)) != -1)
switch (i) {
case 'c':
templatefilename = optarg;
if (strlen(templatefilename) == 0) {
fprintf(stderr, "Requested different config file, but no name given.\n");
return EXIT_FAILURE;
}
break;
case 'h':
fprintf(stderr, "usage: %s [-c config] [-h] -i INTERFACE [-v]\n", argv[0]);
return EXIT_SUCCESS;
case 'i':
interface = optarg;
if (strlen(interface) == 0) {
fprintf(stderr, "No interface given!\n");
return EXIT_FAILURE;
}
break;
case 'v':
verbose++;
break;
}
/* bail if we are not root */
if (getuid() > 0) {
fprintf(stderr, "You need to be root!\n");
goto out;
}
/* check if dhcpd exists and is executable */
if (access(DHCPDFILE, X_OK) == -1) {
fprintf(stderr, "The dhcp daemon is not execatable!\n");
goto out;
}
/* get the domainname */
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;
}
/* give an error if we do not have an interface */
if (interface == NULL) {
fprintf(stderr, "No interface given!\n");
return EXIT_FAILURE;
}
/* initialize ifaddr */
if (getifaddrs(&ifaddr) == -1) {
fprintf(stderr, "getifaddrs() failed.\n");
return EXIT_FAILURE;
}
/* to find the correct interface */
for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
/* next iteration if requirements do not match */
if (strcmp(interface, ifa->ifa_name) != 0)
continue;
if (ifa->ifa_addr == NULL)
continue;
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
/* check if the device is up */
if (!(ifa->ifa_flags & IFF_UP)) {
fprintf(stderr, "Interface %s is down.\n", interface);
goto out;
}
/* check if the device is connected / cable is plugged in
* do warn here, but do not fail */
if (!(ifa->ifa_flags & IFF_RUNNING))
fprintf(stderr, "Warning: Interface %s is not connected.\n", interface);
/* get variables in place for address */
s4 = (struct sockaddr_in *)ifa->ifa_addr;
v_host = &s4->sin_addr;
/* convert address from binary to text form */
if (!inet_ntop(ifa->ifa_addr->sa_family, v_host, c_address, INET_ADDRSTRLEN))
fprintf(stderr, "%s: inet_ntop failed!\n", ifa->ifa_name);
/* get variables in place for netmask */
s4 = (struct sockaddr_in *)ifa->ifa_netmask;
v_mask = &s4->sin_addr;
/* convert netmask from binary to text form */
if (!inet_ntop(ifa->ifa_netmask->sa_family, v_mask, c_netmask, INET_ADDRSTRLEN))
fprintf(stderr, "%s: inet_ntop failed!\n", ifa->ifa_name);
/* calculate broadcast and net address */
s_broadcast.s_addr = v_host->s_addr |~ v_mask->s_addr;
s_netaddress.s_addr = v_host->s_addr & v_mask->s_addr;
/* check if subnet has enough addresses */
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;
}
/* calculate min and max host */
s_minhost.s_addr = htonl(ntohl(s_netaddress.s_addr) + 1);
s_maxhost.s_addr = htonl(ntohl(s_broadcast.s_addr) - 1);
/* convert missing addresses from binary to text form */
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) {
/* print information */
if (verbose)
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);
/* open the template for reading */
if (templatefilename == NULL)
templatefilename = CONFIG_TEMPLATE;
if ((templatefile = fopen(templatefilename, "r")) == NULL) {
fprintf(stderr, "Failed opening config template for reading.\n");
goto out;
}
/* seek to the and so we know the file size */
fseek(templatefile, 0, SEEK_END);
fsize = ftell(templatefile);
fseek(templatefile, 0, SEEK_SET);
/* allocate memory and read file */
template = malloc(fsize + 1);
if ((fread(template, fsize, 1, templatefile)) != 1) {
fprintf(stderr, "Failed reading config template.\n");
goto out;
}
fclose(templatefile);
template[fsize] = 0;
/* replace strings with real values */
for (tmp = template; *tmp;) {
if (*tmp == '_') {
if (strncmp("__INTERFACE__", tmp, 13) == 0) {
config = realloc(config, length + strlen(interface) + 1);
length += sprintf(config + length, interface);
tmp += 13;
} else if (strncmp("__VERSION__", tmp, 11) == 0) {
config = realloc(config, length + strlen(VERSION) + 1);
length += sprintf(config + length, VERSION);
tmp += 11;
} else if (strncmp("__DOMAINNAME__", tmp, 14) == 0) {
config = realloc(config, length + strlen(domainname) + 1);
length += sprintf(config + length, domainname);
tmp += 14;
} else if (strncmp("__ADDRESS__", tmp, 11) == 0) {
config = realloc(config, length + strlen(c_address) + 1);
length += sprintf(config + length, c_address);
tmp += 11;
} else if (strncmp("__NETADDRESS__", tmp, 14) == 0) {
config = realloc(config, length + strlen(c_netaddress) + 1);
length += sprintf(config + length, c_netaddress);
tmp += 14;
} else if (strncmp("__BROADCAST__", tmp, 13) == 0) {
config = realloc(config, length + strlen(c_broadcast) + 1);
length += sprintf(config + length, c_broadcast);
tmp += 13;
} else if (strncmp("__NETMASK__", tmp, 11) == 0) {
config = realloc(config, length + strlen(c_netmask) + 1);
length += sprintf(config + length, c_netmask);
tmp += 11;
} else if (strncmp("__MINHOST__", tmp, 11) == 0) {
config = realloc(config, length + strlen(c_minhost) + 1);
length += sprintf(config + length, c_minhost);
tmp += 11;
} else if (strncmp("__MAXHOST__", tmp, 11) == 0) {
config = realloc(config, length + strlen(c_maxhost) + 1);
length += sprintf(config + length, c_maxhost);
tmp += 11;
} else {
config = realloc(config, length + 1);
config[length++] = *tmp++;
}
} else {
config = realloc(config, length + 1);
config[length++] = *tmp++;
}
}
config = realloc(config, length + 1);
config[length++] = 0;
/* get new filename and open file for writing */
configfilename = malloc(strlen(CONFIG_OUTPUT) + strlen(interface) + 1);
sprintf(configfilename, CONFIG_OUTPUT, interface);
if ((configfile = fopen(configfilename, "w")) == NULL) {
fprintf(stderr, "Failed opening config file for writing.\n");
goto out;
}
/* actually write the final configuration to file and close it */
fputs(config, configfile);
fclose(configfile);
/* get names for pid and leases file */
pidfile = malloc(strlen(PIDFILE) + strlen(interface) + 1);
sprintf(pidfile, PIDFILE, interface);
leasesfile = malloc(strlen(LEASESFILE) + strlen(interface) + 1);
sprintf(leasesfile, LEASESFILE, interface);
/* check if leases file exists, create it if it does not */
if (access(leasesfile, R_OK) == -1) {
if (verbose)
printf("Creating leases file %s.\n", leasesfile);
fclose(fopen(leasesfile, "w"));
}
/* execute dhcp daemon, replace the current process
* dyndhcpd is cleared from memory here and code below is not execuded if
* everything goes well */
if (verbose > 1)
printf("Running: dhcpd -f -q -4 -pf %s -lf %s -cf %s %s\n",
pidfile, leasesfile, configfilename, interface);
rc = execlp(DHCPDFILE, "dhcpd", "-f", "-q", "-4",
"-pf", pidfile, "-lf", leasesfile, "-cf", configfilename, interface, NULL);
fprintf(stderr, "The dhcp daemon failed to execute.\n");
goto out;
} else {
/* failed to convert addresses from binary to string */
fprintf(stderr, "Failed converting number to string\n");
goto out;
}
}
/* we did not find an interface to work with */
fprintf(stderr, "Interface not found, link down or no address.\n");
out:
/* free memory */
if (leasesfile != NULL)
free(leasesfile);
if (pidfile != NULL)
free(pidfile);
if (configfilename != NULL)
free(configfilename);
if (config != NULL)
free(config);
if (template != NULL)
free(template);
if (ifaddr != NULL)
freeifaddrs(ifaddr);
return rc;
}
// vim: set syntax=c:
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