mirror of
https://github.com/pi-hole/dnsmasq.git
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import of dnsmasq-2.0.tar.gz
This commit is contained in:
Simon Kelley
455
src/dnsmasq.c
Normal file
455
src/dnsmasq.c
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@@ -0,0 +1,455 @@
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/* dnsmasq is Copyright (c) 2000-2003 Simon Kelley
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 dated June, 1991.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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*/
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/* See RFC1035 for details of the protocol this code talks. */
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/* Author's email: simon@thekelleys.org.uk */
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#include "dnsmasq.h"
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static int sigterm, sighup, sigusr1, sigusr2;
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static void sig_handler(int sig)
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{
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if (sig == SIGTERM)
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sigterm = 1;
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else if (sig == SIGHUP)
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sighup = 1;
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else if (sig == SIGUSR1)
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sigusr1 = 1;
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else if (sig == SIGUSR2)
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sigusr2 = 1;
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}
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int main (int argc, char **argv)
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{
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char *int_err_string;
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int cachesize = CACHESIZ;
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int port = NAMESERVER_PORT;
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int query_port = 0;
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int first_loop = 1;
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unsigned long local_ttl = 0;
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unsigned int options;
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char *runfile = RUNFILE;
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time_t resolv_changed = 0;
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time_t now, last = 0;
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struct irec *iface, *interfaces = NULL;
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char *mxname = NULL;
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char *mxtarget = NULL;
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char *lease_file = NULL;
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char *addn_hosts = NULL;
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char *domain_suffix = NULL;
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char *username = CHUSER;
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char *groupname = CHGRP;
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struct iname *if_names = NULL;
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struct iname *if_addrs = NULL;
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struct iname *if_except = NULL;
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struct iname *if_tmp;
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struct server *serv_addrs = NULL;
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char *dnamebuff, *packet;
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struct server *servers, *last_server;
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struct resolvc default_resolv = { NULL, 1, 0, RESOLVFILE };
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struct resolvc *resolv = &default_resolv;
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struct bogus_addr *bogus_addr = NULL;
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struct serverfd *serverfdp, *sfds = NULL;
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struct dhcp_context *dhcp_tmp, *dhcp = NULL;
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struct dhcp_config *dhcp_configs = NULL;
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struct dhcp_opt *dhcp_options = NULL;
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char *dhcp_file = NULL, *dhcp_sname = NULL;
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struct in_addr dhcp_next_server;
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int leasefd = 0;
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struct sigaction sigact;
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sigset_t sigmask;
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sighup = 1; /* init cache the first time through */
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sigusr1 = 0; /* but don't dump */
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sigusr2 = 0; /* or rescan interfaces */
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sigterm = 0; /* or die */
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sigact.sa_handler = sig_handler;
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sigact.sa_flags = 0;
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sigemptyset(&sigact.sa_mask);
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sigaction(SIGUSR1, &sigact, NULL);
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sigaction(SIGUSR2, &sigact, NULL);
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sigaction(SIGHUP, &sigact, NULL);
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sigaction(SIGTERM, &sigact, NULL);
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/* now block all the signals, they stay that way except
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during the call to pselect */
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sigaddset(&sigact.sa_mask, SIGUSR1);
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sigaddset(&sigact.sa_mask, SIGUSR2);
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sigaddset(&sigact.sa_mask, SIGTERM);
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sigaddset(&sigact.sa_mask, SIGHUP);
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sigprocmask(SIG_BLOCK, &sigact.sa_mask, &sigmask);
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/* These get allocated here to avoid overflowing the small stack
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on embedded systems. dnamebuff is big enough to hold one
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maximal sixed domain name and gets passed into all the processing
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code. We manage to get away with one buffer. */
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dnamebuff = safe_malloc(MAXDNAME);
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/* Size: we check after adding each record, so there must be
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memory for the largest packet, and the largest record */
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packet = safe_malloc(PACKETSZ+MAXDNAME+RRFIXEDSZ);
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dhcp_next_server.s_addr = 0;
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options = read_opts(argc, argv, dnamebuff, &resolv, &mxname, &mxtarget, &lease_file,
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&username, &groupname, &domain_suffix, &runfile,
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&if_names, &if_addrs, &if_except, &bogus_addr,
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&serv_addrs, &cachesize, &port, &query_port, &local_ttl, &addn_hosts,
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&dhcp, &dhcp_configs, &dhcp_options,
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&dhcp_file, &dhcp_sname, &dhcp_next_server);
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if (!lease_file)
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lease_file = LEASEFILE;
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else
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{
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if (!dhcp)
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{
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complain("********* dhcp-lease option set, but not dhcp-range.", NULL);
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complain("********* Are you trying to use the obsolete ISC dhcpd integration?", NULL);
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complain("********* Please configure the dnsmasq integrated DHCP server by using", NULL);
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complain("********* the \"dhcp-range\" option, and remove any other DHCP server.", NULL);
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}
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}
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if ((int_err_string = enumerate_interfaces(&interfaces, if_names, if_addrs, if_except, dhcp, port)))
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die(int_err_string, NULL);
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for (if_tmp = if_names; if_tmp; if_tmp = if_tmp->next)
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if (if_tmp->name && !if_tmp->found)
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die("unknown interface %s", if_tmp->name);
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for (if_tmp = if_addrs; if_tmp; if_tmp = if_tmp->next)
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if (!if_tmp->found)
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{
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#ifdef HAVE_IPV6
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if (if_tmp->addr.sa.sa_family == AF_INET)
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inet_ntop(AF_INET, &if_tmp->addr.in.sin_addr,
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dnamebuff, MAXDNAME);
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else
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inet_ntop(AF_INET6, &if_tmp->addr.in6.sin6_addr,
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dnamebuff, MAXDNAME);
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die("no interface with address %s", dnamebuff);
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#else
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die("no interface with address %s", inet_ntoa(if_tmp->addr.in.sin_addr));
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#endif
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}
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forward_init(1);
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cache_init(cachesize, options & OPT_LOG);
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if (dhcp)
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{
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#if !defined(HAVE_PF_PACKET) && !defined(HAVE_BPF)
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die("no DHCP support available on this OS.", NULL);
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#endif
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for (dhcp_tmp = dhcp; dhcp_tmp; dhcp_tmp = dhcp_tmp->next)
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if (!dhcp_tmp->iface)
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die("No suitable interface for DHCP service at address %s", inet_ntoa(dhcp_tmp->start));
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leasefd = lease_init(lease_file, domain_suffix, dnamebuff, packet, time(NULL), dhcp_configs);
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lease_update_dns(1); /* must follow cache_init and lease_init */
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}
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setbuf(stdout, NULL);
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if (!(options & OPT_DEBUG))
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{
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FILE *pidfile;
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struct passwd *ent_pw;
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int i;
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/* The following code "daemonizes" the process.
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See Stevens section 12.4 */
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#ifndef NO_FORK
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if (fork() != 0 )
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exit(0);
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setsid();
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if (fork() != 0)
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exit(0);
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#endif
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chdir("/");
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umask(022); /* make pidfile 0644 */
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/* write pidfile _after_ forking ! */
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if (runfile && (pidfile = fopen(runfile, "w")))
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{
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fprintf(pidfile, "%d\n", (int) getpid());
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fclose(pidfile);
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}
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umask(0);
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for (i=0; i<64; i++)
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{
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for (iface = interfaces; iface; iface = iface->next)
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if (iface->fd == i)
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break;
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if (iface)
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continue;
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for (dhcp_tmp = dhcp; dhcp_tmp; dhcp_tmp = dhcp_tmp->next)
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if (dhcp_tmp->fd == i || dhcp_tmp->rawfd == i)
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break;
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if (dhcp_tmp)
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continue;
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if (dhcp && (i == leasefd))
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continue;
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close(i);
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}
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/* Change uid and gid for security */
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if (username && (ent_pw = getpwnam(username)))
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{
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gid_t dummy;
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struct group *gp;
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/* remove all supplimentary groups */
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setgroups(0, &dummy);
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/* change group for /etc/ppp/resolv.conf
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otherwise get the group for "nobody" */
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if ((groupname && (gp = getgrnam(groupname))) ||
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(gp = getgrgid(ent_pw->pw_gid)))
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setgid(gp->gr_gid);
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/* finally drop root */
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setuid(ent_pw->pw_uid);
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}
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}
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openlog("dnsmasq",
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DNSMASQ_LOG_OPT(options & OPT_DEBUG),
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DNSMASQ_LOG_FAC(options & OPT_DEBUG));
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if (cachesize)
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syslog(LOG_INFO, "started, version %s cachesize %d", VERSION, cachesize);
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else
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syslog(LOG_INFO, "started, version %s cache disabled", VERSION);
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if (options & OPT_LOCALMX)
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syslog(LOG_INFO, "serving MX record for local hosts target %s", mxtarget);
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else if (mxname)
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syslog(LOG_INFO, "serving MX record for mailhost %s target %s",
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mxname, mxtarget);
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for (dhcp_tmp = dhcp; dhcp_tmp; dhcp_tmp = dhcp_tmp->next)
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{
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strcpy(dnamebuff, inet_ntoa(dhcp_tmp->start));
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if (dhcp_tmp->lease_time == 0)
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sprintf(packet, "infinite");
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else
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sprintf(packet, "%ds", (int)dhcp_tmp->lease_time);
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syslog(LOG_INFO, "DHCP on %s, IP range %s -- %s, lease time %s",
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dhcp_tmp->iface, dnamebuff, inet_ntoa(dhcp_tmp->end), packet);
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}
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if (getuid() == 0 || geteuid() == 0)
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syslog(LOG_WARNING, "failed to drop root privs");
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servers = last_server = check_servers(serv_addrs, interfaces, &sfds);
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while (sigterm == 0)
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{
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fd_set rset;
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if (sighup)
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{
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cache_reload(options, dnamebuff, domain_suffix, addn_hosts);
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lease_update_dns(1);
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if (resolv && (options & OPT_NO_POLL))
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servers = last_server =
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check_servers(reload_servers(resolv->name, dnamebuff, servers, query_port),
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interfaces, &sfds);
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sighup = 0;
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}
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if (sigusr1)
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{
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dump_cache(options & (OPT_DEBUG | OPT_LOG), cachesize);
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sigusr1 = 0;
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}
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if (sigusr2)
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{
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if (getuid() != 0 && port <= 1024)
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syslog(LOG_ERR, "cannot re-scan interfaces unless --user=root");
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else
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{
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syslog(LOG_INFO, "rescanning network interfaces");
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int_err_string = enumerate_interfaces(&interfaces, if_names, if_addrs, if_except, NULL, port);
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if (int_err_string)
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syslog(LOG_ERR, int_err_string, strerror(errno));
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}
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sigusr2 = 0;
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}
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FD_ZERO(&rset);
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if (!first_loop)
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{
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int maxfd = 0;
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for (serverfdp = sfds; serverfdp; serverfdp = serverfdp->next)
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{
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FD_SET(serverfdp->fd, &rset);
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if (serverfdp->fd > maxfd)
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maxfd = serverfdp->fd;
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}
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for (iface = interfaces; iface; iface = iface->next)
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{
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FD_SET(iface->fd, &rset);
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if (iface->fd > maxfd)
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maxfd = iface->fd;
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}
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for (dhcp_tmp = dhcp; dhcp_tmp; dhcp_tmp = dhcp_tmp->next)
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{
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FD_SET(dhcp_tmp->fd, &rset);
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if (dhcp_tmp->fd > maxfd)
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maxfd = dhcp_tmp->fd;
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}
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#ifdef HAVE_PSELECT
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if (pselect(maxfd+1, &rset, NULL, NULL, NULL, &sigmask) < 0)
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FD_ZERO(&rset); /* rset otherwise undefined after error */
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#else
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{
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sigset_t save_mask;
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sigprocmask(SIG_SETMASK, &sigmask, &save_mask);
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if (select(maxfd+1, &rset, NULL, NULL, NULL) < 0)
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FD_ZERO(&rset); /* rset otherwise undefined after error */
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sigprocmask(SIG_SETMASK, &save_mask, NULL);
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}
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#endif
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}
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first_loop = 0;
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now = time(NULL);
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/* Check for changes to resolv files once per second max. */
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if (last == 0 || difftime(now, last) > 1.0)
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{
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last = now;
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if (!(options & OPT_NO_POLL))
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{
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struct resolvc *res = resolv, *latest = NULL;
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time_t last_change = 0;
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struct stat statbuf;
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/* There may be more than one possible file.
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Go through and find the one which changed _last_.
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Warn of any which can't be read. */
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while (res)
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{
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if (stat(res->name, &statbuf) == -1)
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{
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if (!res->logged)
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syslog(LOG_WARNING, "failed to access %s: %m", res->name);
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res->logged = 1;
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}
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else
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{
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res->logged = 0;
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if (statbuf.st_mtime > last_change)
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{
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last_change = statbuf.st_mtime;
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latest = res;
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}
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}
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res = res->next;
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}
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if (latest && last_change > resolv_changed)
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{
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resolv_changed = last_change;
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servers = last_server =
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check_servers(reload_servers(latest->name, dnamebuff, servers, query_port),
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interfaces, &sfds);
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}
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}
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}
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for (serverfdp = sfds; serverfdp; serverfdp = serverfdp->next)
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if (FD_ISSET(serverfdp->fd, &rset))
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last_server = reply_query(serverfdp->fd, options, packet, now,
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dnamebuff, last_server, bogus_addr);
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for (dhcp_tmp = dhcp; dhcp_tmp; dhcp_tmp = dhcp_tmp->next)
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if (FD_ISSET(dhcp_tmp->fd, &rset))
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dhcp_packet(dhcp_tmp, packet, dhcp_options, dhcp_configs,
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now, dnamebuff, domain_suffix, dhcp_file,
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dhcp_sname, dhcp_next_server);
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for (iface = interfaces; iface; iface = iface->next)
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{
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if (FD_ISSET(iface->fd, &rset))
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{
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/* request packet, deal with query */
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union mysockaddr udpaddr;
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socklen_t udplen = sizeof(udpaddr);
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HEADER *header = (HEADER *)packet;
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int m, n = recvfrom(iface->fd, packet, PACKETSZ, 0, &udpaddr.sa, &udplen);
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udpaddr.sa.sa_family = iface->addr.sa.sa_family;
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#ifdef HAVE_IPV6
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if (udpaddr.sa.sa_family == AF_INET6)
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udpaddr.in6.sin6_flowinfo = htonl(0);
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#endif
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if (n >= (int)sizeof(HEADER) && !header->qr)
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{
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if (extract_request(header, (unsigned int)n, dnamebuff))
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{
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if (udpaddr.sa.sa_family == AF_INET)
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log_query(F_QUERY | F_IPV4 | F_FORWARD, dnamebuff,
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(struct all_addr *)&udpaddr.in.sin_addr);
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#ifdef HAVE_IPV6
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else
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log_query(F_QUERY | F_IPV6 | F_FORWARD, dnamebuff,
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(struct all_addr *)&udpaddr.in6.sin6_addr);
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#endif
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}
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m = answer_request (header, ((char *) header) + PACKETSZ, (unsigned int)n,
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mxname, mxtarget, options, now, local_ttl, dnamebuff);
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if (m >= 1)
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{
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/* answered from cache, send reply */
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sendto(iface->fd, (char *)header, m, 0,
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&udpaddr.sa, sa_len(&udpaddr));
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}
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else
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{
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/* cannot answer from cache, send on to real nameserver */
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last_server = forward_query(iface->fd, &udpaddr, header, n,
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options, dnamebuff, servers,
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last_server, now, local_ttl);
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}
|
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}
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|
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}
|
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}
|
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}
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syslog(LOG_INFO, "exiting on receipt of SIGTERM");
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return 0;
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}
|
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||||
|
||||
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user