/* Copyright 1998 by the Massachusetts Institute of Technology.
*
* Permission to use, copy, modify, and distribute this
* software and its documentation for any purpose and without
* fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting
* documentation, and that the name of M.I.T. not be used in
* advertising or publicity pertaining to distribution of the
* software without specific, written prior permission.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is"
* without express or implied warranty.
*/
static const char rcsid[] = "$Id: ares_init.c,v 1.7 1999/10/23 19:28:13 danw Exp $";
#include <sys/types.h>
#include <sys/time.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#include <netdb.h>
#include "ares.h"
#include "ares_private.h"
static int init_by_options(ares_channel channel, struct ares_options *options,
int optmask);
static int init_by_environment(ares_channel channel);
static int init_by_resolv_conf(ares_channel channel);
static int init_by_defaults(ares_channel channel);
static int config_domain(ares_channel channel, char *str);
static int config_lookup(ares_channel channel, const char *str);
static int config_nameserver(struct server_state **servers, int *nservers,
const char *str);
static int config_sortlist(struct apattern **sortlist, int *nsort,
const char *str);
static int set_search(ares_channel channel, const char *str);
static int set_options(ares_channel channel, const char *str);
static char *try_config(char *s, char *opt);
static const char *try_option(const char *p, const char *q, const char *opt);
static int ip_addr(const char *s, int len, struct in_addr *addr);
static void natural_mask(struct apattern *pat);
int ares_init(ares_channel *channelptr)
{
return ares_init_options(channelptr, NULL, 0);
}
int ares_init_options(ares_channel *channelptr, struct ares_options *options,
int optmask)
{
ares_channel channel;
int i, status;
struct server_state *server;
struct timeval tv;
channel = malloc(sizeof(struct ares_channeldata));
if (!channel)
return ARES_ENOMEM;
/* Set everything to distinguished values so we know they haven't
* been set yet.
*/
channel->flags = -1;
channel->timeout = -1;
channel->tries = -1;
channel->ndots = -1;
channel->udp_port = -1;
channel->tcp_port = -1;
channel->nservers = -1;
channel->ndomains = -1;
channel->nsort = -1;
channel->lookups = NULL;
/* Initialize configuration by each of the four sources, from highest
* precedence to lowest.
*/
status = init_by_options(channel, options, optmask);
if (status == ARES_SUCCESS)
status = init_by_environment(channel);
if (status == ARES_SUCCESS)
status = init_by_resolv_conf(channel);
if (status == ARES_SUCCESS)
status = init_by_defaults(channel);
if (status != ARES_SUCCESS)
{
/* Something failed; clean up memory we may have allocated. */
if (channel->nservers != -1)
free(channel->servers);
if (channel->ndomains != -1)
{
for (i = 0; i < channel->ndomains; i++)
free(channel->domains[i]);
free(channel->domains);
}
if (channel->nsort != -1)
free(channel->sortlist);
free(channel->lookups);
free(channel);
return status;
}
/* Trim to one server if ARES_FLAG_PRIMARY is set. */
if ((channel->flags & ARES_FLAG_PRIMARY) && channel->nservers > 1)
channel->nservers = 1;
/* Initialize server states. */
for (i = 0; i < channel->nservers; i++)
{
server = &channel->servers[i];
server->udp_socket = -1;
server->tcp_socket = -1;
server->tcp_lenbuf_pos = 0;
server->tcp_buffer = NULL;
server->qhead = NULL;
server->qtail = NULL;
}
/* Choose a somewhat random query ID. The main point is to avoid
* collisions with stale queries. An attacker trying to spoof a DNS
* answer also has to guess the query ID, but it's only a 16-bit
* field, so there's not much to be done about that.
*/
gettimeofday(&tv, NULL);
channel->next_id = (tv.tv_sec ^ tv.tv_usec ^ getpid()) & 0xffff;
channel->queries = NULL;
*channelptr = channel;
return ARES_SUCCESS;
}
static int init_by_options(ares_channel channel, struct ares_options *options,
int optmask)
{
int i;
/* Easy stuff. */
if ((optmask & ARES_OPT_FLAGS) && channel->flags == -1)
channel->flags = options->flags;
if ((optmask & ARES_OPT_TIMEOUT) && channel->timeout == -1)
channel->timeout = options->timeout;
if ((optmask & ARES_OPT_TRIES) && channel->tries == -1)
channel->tries = options->tries;
if ((optmask & ARES_OPT_NDOTS) && channel->ndots == -1)
channel->ndots = options->ndots;
if ((optmask & ARES_OPT_UDP_PORT) && channel->udp_port == -1)
channel->udp_port = options->udp_port;
if ((optmask & ARES_OPT_TCP_PORT) && channel->tcp_port == -1)
channel->tcp_port = options->tcp_port;
/* Copy the servers, if given. */
if ((optmask & ARES_OPT_SERVERS) && channel->nservers == -1)
{
channel->servers =
malloc(options->nservers * sizeof(struct server_state));
if (!channel->servers && options->nservers != 0)
return ARES_ENOMEM;
for (i = 0; i < options->nservers; i++)
channel->servers[i].addr = options->servers[i];
channel->nservers = options->nservers;
}
/* Copy the domains, if given. Keep channel->ndomains consistent so
* we can clean up in case of error.
*/
if ((optmask & ARES_OPT_DOMAINS) && channel->ndomains == -1)
{
channel->domains = malloc(options->ndomains * sizeof(char *));
if (!channel->domains && options->ndomains != 0)
return ARES_ENOMEM;
for (i = 0; i < options->ndomains; i++)
{
channel->ndomains = i;
channel->domains[i] = strdup(options->domains[i]);
if (!channel->domains[i])
return ARES_ENOMEM;
}
channel->ndomains = options->ndomains;
}
/* Set lookups, if given. */
if ((optmask & ARES_OPT_LOOKUPS) && !channel->lookups)
{
channel->lookups = strdup(options->lookups);
if (!channel->lookups)
return ARES_ENOMEM;
}
return ARES_SUCCESS;
}
static int init_by_environment(ares_channel channel)
{
const char *localdomain, *res_options;
int status;
localdomain = getenv("LOCALDOMAIN");
if (localdomain && channel->ndomains == -1)
{
status = set_search(channel, localdomain);
if (status != ARES_SUCCESS)
return status;
}
res_options = getenv("RES_OPTIONS");
if (res_options)
{
status = set_options(channel, res_options);
if (status != ARES_SUCCESS)
return status;
}
return ARES_SUCCESS;
}
static int init_by_resolv_conf(ares_channel channel)
{
FILE *fp;
char *line = NULL, *p;
int linesize, status, nservers = 0, nsort = 0;
struct server_state *servers = NULL;
struct apattern *sortlist = NULL;
fp = fopen(PATH_RESOLV_CONF, "r");
if (!fp)
return (errno == ENOENT) ? ARES_SUCCESS : ARES_EFILE;
while ((status = ares__read_line(fp, &line, &linesize)) == ARES_SUCCESS)
{
if ((p = try_config(line, "domain")) && channel->ndomains == -1)
status = config_domain(channel, p);
else if ((p = try_config(line, "lookup")) && !channel->lookups)
status = config_lookup(channel, p);
else if ((p = try_config(line, "search")) && channel->ndomains == -1)
status = set_search(channel, p);
else if ((p = try_config(line, "nameserver")) && channel->nservers == -1)
status = config_nameserver(&servers, &nservers, p);
else if ((p = try_config(line, "sortlist")) && channel->nsort == -1)
status = config_sortlist(&sortlist, &nsort, p);
else if ((p = try_config(line, "options")))
status = set_options(channel, p);
else
status = ARES_SUCCESS;
if (status != ARES_SUCCESS)
break;
}
free(line);
fclose(fp);
/* Handle errors. */
if (status != ARES_EOF)
{
free(servers);
free(sortlist);
return status;
}
/* If we got any name server entries, fill them in. */
if (servers)
{
channel->servers = servers;
channel->nservers = nservers;
}
/* If we got any sortlist entries, fill them in. */
if (sortlist)
{
channel->sortlist = sortlist;
channel->nsort = nsort;
}
return ARES_SUCCESS;
}
static int init_by_defaults(ares_channel channel)
{
char hostname[MAXHOSTNAMELEN + 1];
if (channel->flags == -1)
channel->flags = 0;
if (channel->timeout == -1)
channel->timeout = DEFAULT_TIMEOUT;
if (channel->tries == -1)
channel->tries = DEFAULT_TRIES;
if (channel->ndots == -1)
channel->ndots = 1;
if (channel->udp_port == -1)
channel->udp_port = htons(NAMESERVER_PORT);
if (channel->tcp_port == -1)
channel->tcp_port = htons(NAMESERVER_PORT);
if (channel->nservers == -1)
{
/* If nobody specified servers, try a local named. */
channel->servers = malloc(sizeof(struct server_state));
if (!channel->servers)
return ARES_ENOMEM;
channel->servers[0].addr.s_addr = htonl(INADDR_LOOPBACK);
channel->nservers = 1;
}
if (channel->ndomains == -1)
{
/* Derive a default domain search list from the kernel hostname,
* or set it to empty if the hostname isn't helpful.
*/
if (gethostname(hostname, sizeof(hostname)) == -1
|| !strchr(hostname, '.'))
{
channel->domains = malloc(0);
channel->ndomains = 0;
}
else
{
channel->domains = malloc(sizeof(char *));
if (!channel->domains)
return ARES_ENOMEM;
channel->ndomains = 0;
channel->domains[0] = strdup(strchr(hostname, '.') + 1);
if (!channel->domains[0])
return ARES_ENOMEM;
channel->ndomains = 1;
}
}
if (channel->nsort == -1)
{
channel->sortlist = NULL;
channel->nsort = 0;
}
if (!channel->lookups)
{
channel->lookups = strdup("bf");
if (!channel->lookups)
return ARES_ENOMEM;
}
return ARES_SUCCESS;
}
static int config_domain(ares_channel channel, char *str)
{
char *q;
/* Set a single search domain. */
q = str;
while (*q && !isspace((unsigned char)*q))
q++;
*q = 0;
return set_search(channel, str);
}
static int config_lookup(ares_channel channel, const char *str)
{
char lookups[3], *l;
const char *p;
/* Set the lookup order. Only the first letter of each work
* is relevant, and it has to be "b" for DNS or "f" for the
* host file. Ignore everything else.
*/
l = lookups;
p = str;
while (*p)
{
if ((*p == 'b' || *p == 'f') && l < lookups + 2)
*l++ = *p;
while (*p && !isspace((unsigned char)*p))
p++;
while (isspace((unsigned char)*p))
p++;
}
*l = 0;
channel->lookups = strdup(lookups);
return (channel->lookups) ? ARES_SUCCESS : ARES_ENOMEM;
}
static int config_nameserver(struct server_state **servers, int *nservers,
const char *str)
{
struct in_addr addr;
struct server_state *newserv;
/* Add a nameserver entry, if this is a valid address. */
addr.s_addr = inet_addr(str);
if (addr.s_addr == INADDR_NONE)
return ARES_SUCCESS;
newserv = realloc(*servers, (*nservers + 1) * sizeof(struct server_state));
if (!newserv)
return ARES_ENOMEM;
newserv[*nservers].addr = addr;
*servers = newserv;
(*nservers)++;
return ARES_SUCCESS;
}
static int config_sortlist(struct apattern **sortlist, int *nsort,
const char *str)
{
struct apattern pat, *newsort;
const char *q;
/* Add sortlist entries. */
while (*str && *str != ';')
{
q = str;
while (*q && *q != '/' && *q != ';' && !isspace((unsigned char)*q))
q++;
if (ip_addr(str, q - str, &pat.addr) == 0)
{
/* We have a pattern address; now determine the mask. */
if (*q == '/')
{
str = q + 1;
while (*q && *q != ';' && !isspace((unsigned char)*q))
q++;
if (ip_addr(str, q - str, &pat.mask) != 0)
natural_mask(&pat);
}
else
natural_mask(&pat);
/* Add this pattern to our list. */
newsort = realloc(*sortlist, (*nsort + 1) * sizeof(struct apattern));
if (!newsort)
return ARES_ENOMEM;
newsort[*nsort] = pat;
*sortlist = newsort;
(*nsort)++;
}
else
{
while (*q && *q != ';' && !isspace((unsigned char)*q))
q++;
}
str = q;
while (isspace((unsigned char)*str))
str++;
}
return ARES_SUCCESS;
}
static int set_search(ares_channel channel, const char *str)
{
int n;
const char *p, *q;
/* Count the domains given. */
n = 0;
p = str;
while (*p)
{
while (*p && !isspace((unsigned char)*p))
p++;
while (isspace((unsigned char)*p))
p++;
n++;
}
channel->domains = malloc(n * sizeof(char *));
if (!channel->domains && n)
return ARES_ENOMEM;
/* Now copy the domains. */
n = 0;
p = str;
while (*p)
{
channel->ndomains = n;
q = p;
while (*q && !isspace((unsigned char)*q))
q++;
channel->domains[n] = malloc(q - p + 1);
if (!channel->domains[n])
return ARES_ENOMEM;
memcpy(channel->domains[n], p, q - p);
channel->domains[n][q - p] = 0;
p = q;
while (isspace((unsigned char)*p))
p++;
n++;
}
channel->ndomains = n;
return ARES_SUCCESS;
}
static int set_options(ares_channel channel, const char *str)
{
const char *p, *q, *val;
p = str;
while (*p)
{
q = p;
while (*q && !isspace((unsigned char)*q))
q++;
val = try_option(p, q, "ndots:");
if (val && channel->ndots == -1)
channel->ndots = atoi(val);
val = try_option(p, q, "retrans:");
if (val && channel->timeout == -1)
channel->timeout = atoi(val);
val = try_option(p, q, "retry:");
if (val && channel->tries == -1)
channel->tries = atoi(val);
p = q;
while (isspace((unsigned char)*p))
p++;
}
return ARES_SUCCESS;
}
static char *try_config(char *s, char *opt)
{
int len;
len = strlen(opt);
if (strncmp(s, opt, len) != 0 || !isspace((unsigned char)s[len]))
return NULL;
s += len;
while (isspace((unsigned char)*s))
s++;
return s;
}
static const char *try_option(const char *p, const char *q, const char *opt)
{
int len;
len = strlen(opt);
return (q - p > len && strncmp(p, opt, len) == 0) ? p + len : NULL;
}
static int ip_addr(const char *s, int len, struct in_addr *addr)
{
char ipbuf[16];
/* Four octets and three periods yields at most 15 characters. */
if (len > 15)
return -1;
memcpy(ipbuf, s, len);
ipbuf[len] = 0;
addr->s_addr = inet_addr(ipbuf);
if (addr->s_addr == INADDR_NONE && strcmp(ipbuf, "255.255.255.255") != 0)
return -1;
return 0;
}
static void natural_mask(struct apattern *pat)
{
struct in_addr addr;
/* Store a host-byte-order copy of pat in a struct in_addr. Icky,
* but portable.
*/
addr.s_addr = ntohl(pat->addr.s_addr);
/* This is out of date in the CIDR world, but some people might
* still rely on it.
*/
if (IN_CLASSA(addr.s_addr))
pat->mask.s_addr = htonl(IN_CLASSA_NET);
else if (IN_CLASSB(addr.s_addr))
pat->mask.s_addr = htonl(IN_CLASSB_NET);
else
pat->mask.s_addr = htonl(IN_CLASSC_NET);
}
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