mirror of
https://github.com/matrix-construct/construct
synced 2024-08-30 21:35:18 +02:00
912 lines
22 KiB
C
912 lines
22 KiB
C
/*
|
|
* A rewrite of Darren Reeds original res.c As there is nothing
|
|
* left of Darrens original code, this is now licensed by the hybrid group.
|
|
* (Well, some of the function names are the same, and bits of the structs..)
|
|
* You can use it where it is useful, free even. Buy us a beer and stuff.
|
|
*
|
|
* The authors takes no responsibility for any damage or loss
|
|
* of property which results from the use of this software.
|
|
*
|
|
* July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
|
|
* added callbacks and reference counting of returned hostents.
|
|
* --Bleep (Thomas Helvey <tomh@inxpress.net>)
|
|
*
|
|
* This was all needlessly complicated for irc. Simplified. No more hostent
|
|
* All we really care about is the IP -> hostname mappings. Thats all.
|
|
*
|
|
* Apr 28, 2003 --cryogen and Dianora
|
|
*
|
|
* DNS server flooding lessened, AAAA-or-A lookup removed, ip6.int support
|
|
* removed, various robustness fixes
|
|
*
|
|
* 2006 --jilles and nenolod
|
|
*
|
|
* Resend queries to other servers if the DNS server replies with an error or
|
|
* an invalid response. Also, avoid servers that return errors or invalid
|
|
* responses.
|
|
*
|
|
* October 2012 --mr_flea
|
|
*
|
|
* ircd-ratbox changes for random IDs merged back in.
|
|
*
|
|
* January 2016 --kaniini
|
|
*/
|
|
|
|
#include <rb_lib.h>
|
|
#include "setup.h"
|
|
#include "res.h"
|
|
#include "reslib.h"
|
|
|
|
#if (CHAR_BIT != 8)
|
|
#error this code needs to be able to address individual octets
|
|
#endif
|
|
|
|
static PF res_readreply;
|
|
|
|
#define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
|
|
#define RES_MAXALIASES 35 /* maximum aliases allowed */
|
|
#define RES_MAXADDRS 35 /* maximum addresses allowed */
|
|
#define AR_TTL 600 /* TTL in seconds for dns cache entries */
|
|
|
|
/* RFC 1104/1105 wasn't very helpful about what these fields
|
|
* should be named, so for now, we'll just name them this way.
|
|
* we probably should look at what named calls them or something.
|
|
*/
|
|
#define TYPE_SIZE (size_t)2
|
|
#define CLASS_SIZE (size_t)2
|
|
#define TTL_SIZE (size_t)4
|
|
#define RDLENGTH_SIZE (size_t)2
|
|
#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
|
|
|
|
#ifdef RB_IPV6
|
|
struct in6_addr ipv6_addr;
|
|
#endif
|
|
struct in_addr ipv4_addr;
|
|
|
|
struct reslist
|
|
{
|
|
rb_dlink_node node;
|
|
int id;
|
|
time_t ttl;
|
|
char type;
|
|
char queryname[IRCD_RES_HOSTLEN + 1]; /* name currently being queried */
|
|
char retries; /* retry counter */
|
|
char sends; /* number of sends (>1 means resent) */
|
|
time_t sentat;
|
|
time_t timeout;
|
|
int lastns; /* index of last server sent to */
|
|
struct rb_sockaddr_storage addr;
|
|
char *name;
|
|
struct DNSQuery *query; /* query callback for this request */
|
|
};
|
|
|
|
static rb_fde_t *res_fd;
|
|
static rb_dlink_list request_list = { NULL, NULL, 0 };
|
|
static int ns_failure_count[IRCD_MAXNS]; /* timeouts and invalid/failed replies */
|
|
|
|
static void rem_request(struct reslist *request);
|
|
static struct reslist *make_request(struct DNSQuery *query);
|
|
static void gethost_byname_type_fqdn(const char *name, struct DNSQuery *query,
|
|
int type);
|
|
static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, int);
|
|
static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *,
|
|
struct reslist *request);
|
|
static void query_name(struct reslist *request);
|
|
static int send_res_msg(const char *buf, int len, int count);
|
|
static void resend_query(struct reslist *request);
|
|
static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob);
|
|
static int proc_answer(struct reslist *request, HEADER * header, char *, char *);
|
|
static struct reslist *find_id(int id);
|
|
static struct DNSReply *make_dnsreply(struct reslist *request);
|
|
static uint16_t generate_random_id(void);
|
|
|
|
#ifdef RES_MIN
|
|
#undef RES_MIN
|
|
#endif
|
|
|
|
#define RES_MIN(a, b) ((a) < (b) ? (a) : (b))
|
|
|
|
/*
|
|
* int
|
|
* res_ourserver(inp)
|
|
* looks up "inp" in irc_nsaddr_list[]
|
|
* returns:
|
|
* server ID or -1 for not found
|
|
* author:
|
|
* paul vixie, 29may94
|
|
* revised for ircd, cryogen(stu) may03
|
|
* slightly modified for charybdis, mr_flea oct12
|
|
*/
|
|
static int
|
|
res_ourserver(const struct rb_sockaddr_storage *inp)
|
|
{
|
|
#ifdef RB_IPV6
|
|
const struct sockaddr_in6 *v6;
|
|
const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp;
|
|
#endif
|
|
const struct sockaddr_in *v4;
|
|
const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp;
|
|
int ns;
|
|
|
|
for(ns = 0; ns < irc_nscount; ns++)
|
|
{
|
|
const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns];
|
|
#ifdef RB_IPV6
|
|
v6 = (const struct sockaddr_in6 *)srv;
|
|
#endif
|
|
v4 = (const struct sockaddr_in *)srv;
|
|
|
|
/* could probably just memcmp(srv, inp, srv.ss_len) here
|
|
* but we'll air on the side of caution - stu
|
|
*/
|
|
switch (GET_SS_FAMILY(srv))
|
|
{
|
|
#ifdef RB_IPV6
|
|
case AF_INET6:
|
|
if(GET_SS_FAMILY(srv) == GET_SS_FAMILY(inp))
|
|
if(v6->sin6_port == v6in->sin6_port)
|
|
if((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
|
|
sizeof(struct in6_addr)) == 0) ||
|
|
(memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
|
|
sizeof(struct in6_addr)) == 0))
|
|
return 1;
|
|
break;
|
|
#endif
|
|
case AF_INET:
|
|
if(GET_SS_FAMILY(srv) == GET_SS_FAMILY(inp))
|
|
if(v4->sin_port == v4in->sin_port)
|
|
if((v4->sin_addr.s_addr == INADDR_ANY)
|
|
|| (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
|
|
return 1;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* timeout_query_list - Remove queries from the list which have been
|
|
* there too long without being resolved.
|
|
*/
|
|
static time_t timeout_query_list(time_t now)
|
|
{
|
|
rb_dlink_node *ptr;
|
|
rb_dlink_node *next_ptr;
|
|
struct reslist *request;
|
|
time_t next_time = 0;
|
|
time_t timeout = 0;
|
|
|
|
RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
|
|
{
|
|
request = ptr->data;
|
|
timeout = request->sentat + request->timeout;
|
|
|
|
if (now >= timeout)
|
|
{
|
|
ns_failure_count[request->lastns]++;
|
|
request->sentat = now;
|
|
request->timeout += request->timeout;
|
|
resend_query(request);
|
|
}
|
|
|
|
if ((next_time == 0) || timeout < next_time)
|
|
{
|
|
next_time = timeout;
|
|
}
|
|
}
|
|
|
|
return (next_time > now) ? next_time : (now + AR_TTL);
|
|
}
|
|
|
|
/*
|
|
* timeout_resolver - check request list
|
|
*/
|
|
static void timeout_resolver(void *notused)
|
|
{
|
|
timeout_query_list(rb_current_time());
|
|
}
|
|
|
|
static struct ev_entry *timeout_resolver_ev = NULL;
|
|
|
|
/*
|
|
* start_resolver - do everything we need to read the resolv.conf file
|
|
* and initialize the resolver file descriptor if needed
|
|
*/
|
|
static void start_resolver(void)
|
|
{
|
|
int i;
|
|
|
|
irc_res_init();
|
|
for (i = 0; i < irc_nscount; i++)
|
|
ns_failure_count[i] = 0;
|
|
|
|
if (res_fd == NULL)
|
|
{
|
|
if ((res_fd = rb_socket(GET_SS_FAMILY(&irc_nsaddr_list[0]), SOCK_DGRAM, 0,
|
|
"UDP resolver socket")) == NULL)
|
|
return;
|
|
|
|
/* At the moment, the resolver FD data is global .. */
|
|
rb_setselect(res_fd, RB_SELECT_READ, res_readreply, NULL);
|
|
timeout_resolver_ev = rb_event_add("timeout_resolver", timeout_resolver, NULL, 1);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* init_resolver - initialize resolver and resolver library
|
|
*/
|
|
void init_resolver(void)
|
|
{
|
|
#ifdef HAVE_SRAND48
|
|
srand48(rb_current_time());
|
|
#endif
|
|
start_resolver();
|
|
}
|
|
|
|
/*
|
|
* restart_resolver - reread resolv.conf, reopen socket
|
|
*/
|
|
void restart_resolver(void)
|
|
{
|
|
rb_close(res_fd);
|
|
res_fd = NULL;
|
|
rb_event_delete(timeout_resolver_ev); /* -ddosen */
|
|
start_resolver();
|
|
}
|
|
|
|
/*
|
|
* add_local_domain - Add the domain to hostname, if it is missing
|
|
* (as suggested by eps@TOASTER.SFSU.EDU)
|
|
*/
|
|
void add_local_domain(char *hname, size_t size)
|
|
{
|
|
/* try to fix up unqualified names */
|
|
if (strchr(hname, '.') == NULL)
|
|
{
|
|
if (irc_domain[0])
|
|
{
|
|
size_t len = strlen(hname);
|
|
|
|
if ((strlen(irc_domain) + len + 2) < size)
|
|
{
|
|
hname[len++] = '.';
|
|
strcpy(hname + len, irc_domain);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* rem_request - remove a request from the list.
|
|
* This must also free any memory that has been allocated for
|
|
* temporary storage of DNS results.
|
|
*/
|
|
static void rem_request(struct reslist *request)
|
|
{
|
|
rb_dlinkDelete(&request->node, &request_list);
|
|
rb_free(request->name);
|
|
rb_free(request);
|
|
}
|
|
|
|
/*
|
|
* make_request - Create a DNS request record for the server.
|
|
*/
|
|
static struct reslist *make_request(struct DNSQuery *query)
|
|
{
|
|
struct reslist *request = rb_malloc(sizeof(struct reslist));
|
|
|
|
request->sentat = rb_current_time();
|
|
request->retries = 3;
|
|
request->timeout = 4; /* start at 4 and exponential inc. */
|
|
request->query = query;
|
|
|
|
/*
|
|
* generate a unique id
|
|
* NOTE: we don't have to worry about converting this to and from
|
|
* network byte order, the nameserver does not interpret this value
|
|
* and returns it unchanged
|
|
*
|
|
* we generate an id per request now (instead of per send) to allow
|
|
* late replies to be used.
|
|
*/
|
|
request->id = generate_random_id();
|
|
|
|
rb_dlinkAdd(request, &request->node, &request_list);
|
|
|
|
return request;
|
|
}
|
|
|
|
/*
|
|
* retryfreq - determine how many queries to wait before resending
|
|
* if there have been that many consecutive timeouts
|
|
*
|
|
* This is a cubic backoff btw, if anyone didn't pick up on it. --Elizafox
|
|
*/
|
|
static int retryfreq(int timeouts)
|
|
{
|
|
switch (timeouts)
|
|
{
|
|
case 1:
|
|
return 3;
|
|
case 2:
|
|
return 9;
|
|
case 3:
|
|
return 27;
|
|
case 4:
|
|
return 81;
|
|
default:
|
|
return 243;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* send_res_msg - sends msg to a nameserver.
|
|
* This should reflect /etc/resolv.conf.
|
|
* Returns number of nameserver successfully sent to
|
|
* or -1 if no successful sends.
|
|
*/
|
|
static int send_res_msg(const char *msg, int len, int rcount)
|
|
{
|
|
int i;
|
|
int ns;
|
|
static int retrycnt;
|
|
|
|
retrycnt++;
|
|
/* First try a nameserver that seems to work.
|
|
* Every once in a while, try a possibly broken one to check
|
|
* if it is working again.
|
|
*/
|
|
for (i = 0; i < irc_nscount; i++)
|
|
{
|
|
ns = (i + rcount - 1) % irc_nscount;
|
|
if (ns_failure_count[ns] && retrycnt % retryfreq(ns_failure_count[ns]))
|
|
continue;
|
|
if (sendto(rb_get_fd(res_fd), msg, len, 0,
|
|
(struct sockaddr *)&(irc_nsaddr_list[ns]),
|
|
GET_SS_LEN(&irc_nsaddr_list[ns])) == len)
|
|
return ns;
|
|
}
|
|
|
|
/* No known working nameservers, try some broken one. */
|
|
for (i = 0; i < irc_nscount; i++)
|
|
{
|
|
ns = (i + rcount - 1) % irc_nscount;
|
|
if (!ns_failure_count[ns])
|
|
continue;
|
|
if (sendto(rb_get_fd(res_fd), msg, len, 0,
|
|
(struct sockaddr *)&(irc_nsaddr_list[ns]),
|
|
GET_SS_LEN(&irc_nsaddr_list[ns])) == len)
|
|
return ns;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* find_id - find a dns request id (id is determined by dn_mkquery)
|
|
*/
|
|
static struct reslist *find_id(int id)
|
|
{
|
|
rb_dlink_node *ptr;
|
|
struct reslist *request;
|
|
|
|
RB_DLINK_FOREACH(ptr, request_list.head)
|
|
{
|
|
request = ptr->data;
|
|
|
|
if (request->id == id)
|
|
return (request);
|
|
}
|
|
|
|
return (NULL);
|
|
}
|
|
|
|
static uint16_t
|
|
generate_random_id(void)
|
|
{
|
|
uint16_t id;
|
|
|
|
do
|
|
{
|
|
rb_get_random(&id, sizeof(id));
|
|
if(id == 0xffff)
|
|
continue;
|
|
}
|
|
while(find_id(id));
|
|
return id;
|
|
}
|
|
|
|
/*
|
|
* gethost_byname_type - get host address from name, adding domain if needed
|
|
*/
|
|
void gethost_byname_type(const char *name, struct DNSQuery *query, int type)
|
|
{
|
|
char fqdn[IRCD_RES_HOSTLEN + 1];
|
|
assert(name != 0);
|
|
|
|
rb_strlcpy(fqdn, name, sizeof fqdn);
|
|
add_local_domain(fqdn, IRCD_RES_HOSTLEN);
|
|
gethost_byname_type_fqdn(fqdn, query, type);
|
|
}
|
|
|
|
/*
|
|
* gethost_byname_type_fqdn - get host address from fqdn
|
|
*/
|
|
static void gethost_byname_type_fqdn(const char *name, struct DNSQuery *query,
|
|
int type)
|
|
{
|
|
assert(name != 0);
|
|
do_query_name(query, name, NULL, type);
|
|
}
|
|
|
|
/*
|
|
* gethost_byaddr - get host name from address
|
|
*/
|
|
void gethost_byaddr(const struct rb_sockaddr_storage *addr, struct DNSQuery *query)
|
|
{
|
|
do_query_number(query, addr, NULL);
|
|
}
|
|
|
|
/*
|
|
* do_query_name - nameserver lookup name
|
|
*/
|
|
static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request,
|
|
int type)
|
|
{
|
|
if (request == NULL)
|
|
{
|
|
request = make_request(query);
|
|
request->name = rb_strdup(name);
|
|
}
|
|
|
|
rb_strlcpy(request->queryname, name, sizeof(request->queryname));
|
|
request->type = type;
|
|
query_name(request);
|
|
}
|
|
|
|
/* Build an rDNS style query - if suffix is NULL, use the appropriate .arpa zone */
|
|
void build_rdns(char *buf, size_t size, const struct rb_sockaddr_storage *addr, const char *suffix)
|
|
{
|
|
const unsigned char *cp;
|
|
|
|
if (GET_SS_FAMILY(addr) == AF_INET)
|
|
{
|
|
const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr;
|
|
cp = (const unsigned char *)&v4->sin_addr.s_addr;
|
|
|
|
(void) snprintf(buf, size, "%u.%u.%u.%u.%s",
|
|
(unsigned int)(cp[3]),
|
|
(unsigned int)(cp[2]),
|
|
(unsigned int)(cp[1]),
|
|
(unsigned int)(cp[0]),
|
|
suffix == NULL ? "in-addr.arpa" : suffix);
|
|
}
|
|
#ifdef RB_IPV6
|
|
else if (GET_SS_FAMILY(addr) == AF_INET6)
|
|
{
|
|
const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr;
|
|
cp = (const unsigned char *)&v6->sin6_addr.s6_addr;
|
|
|
|
(void) snprintf(buf, size,
|
|
"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%s",
|
|
(unsigned int)(cp[15] & 0xf), (unsigned int)(cp[15] >> 4),
|
|
(unsigned int)(cp[14] & 0xf), (unsigned int)(cp[14] >> 4),
|
|
(unsigned int)(cp[13] & 0xf), (unsigned int)(cp[13] >> 4),
|
|
(unsigned int)(cp[12] & 0xf), (unsigned int)(cp[12] >> 4),
|
|
(unsigned int)(cp[11] & 0xf), (unsigned int)(cp[11] >> 4),
|
|
(unsigned int)(cp[10] & 0xf), (unsigned int)(cp[10] >> 4),
|
|
(unsigned int)(cp[9] & 0xf), (unsigned int)(cp[9] >> 4),
|
|
(unsigned int)(cp[8] & 0xf), (unsigned int)(cp[8] >> 4),
|
|
(unsigned int)(cp[7] & 0xf), (unsigned int)(cp[7] >> 4),
|
|
(unsigned int)(cp[6] & 0xf), (unsigned int)(cp[6] >> 4),
|
|
(unsigned int)(cp[5] & 0xf), (unsigned int)(cp[5] >> 4),
|
|
(unsigned int)(cp[4] & 0xf), (unsigned int)(cp[4] >> 4),
|
|
(unsigned int)(cp[3] & 0xf), (unsigned int)(cp[3] >> 4),
|
|
(unsigned int)(cp[2] & 0xf), (unsigned int)(cp[2] >> 4),
|
|
(unsigned int)(cp[1] & 0xf), (unsigned int)(cp[1] >> 4),
|
|
(unsigned int)(cp[0] & 0xf), (unsigned int)(cp[0] >> 4),
|
|
suffix == NULL ? "ip6.arpa" : suffix);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* do_query_number - Use this to do reverse IP# lookups.
|
|
*/
|
|
static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *addr,
|
|
struct reslist *request)
|
|
{
|
|
if (request == NULL)
|
|
{
|
|
request = make_request(query);
|
|
memcpy(&request->addr, addr, sizeof(struct rb_sockaddr_storage));
|
|
request->name = (char *)rb_malloc(IRCD_RES_HOSTLEN + 1);
|
|
}
|
|
|
|
build_rdns(request->queryname, IRCD_RES_HOSTLEN + 1, addr, NULL);
|
|
|
|
request->type = T_PTR;
|
|
query_name(request);
|
|
}
|
|
|
|
/*
|
|
* query_name - generate a query based on class, type and name.
|
|
*/
|
|
static void query_name(struct reslist *request)
|
|
{
|
|
char buf[MAXPACKET];
|
|
int request_len = 0;
|
|
int ns;
|
|
|
|
memset(buf, 0, sizeof(buf));
|
|
|
|
if ((request_len =
|
|
irc_res_mkquery(request->queryname, C_IN, request->type, (unsigned char *)buf, sizeof(buf))) > 0)
|
|
{
|
|
HEADER *header = (HEADER *)(void *)buf;
|
|
header->id = request->id;
|
|
++request->sends;
|
|
|
|
ns = send_res_msg(buf, request_len, request->sends);
|
|
if (ns != -1)
|
|
request->lastns = ns;
|
|
}
|
|
}
|
|
|
|
static void resend_query(struct reslist *request)
|
|
{
|
|
if (--request->retries <= 0)
|
|
{
|
|
(*request->query->callback) (request->query->ptr, NULL);
|
|
rem_request(request);
|
|
return;
|
|
}
|
|
|
|
switch (request->type)
|
|
{
|
|
case T_PTR:
|
|
do_query_number(NULL, &request->addr, request);
|
|
break;
|
|
case T_A:
|
|
#ifdef RB_IPV6
|
|
case T_AAAA:
|
|
#endif
|
|
do_query_name(NULL, request->name, request, request->type);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* check_question - check if the reply really belongs to the
|
|
* name we queried (to guard against late replies from previous
|
|
* queries with the same id).
|
|
*/
|
|
static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob)
|
|
{
|
|
char hostbuf[IRCD_RES_HOSTLEN + 1]; /* working buffer */
|
|
unsigned char *current; /* current position in buf */
|
|
int n; /* temp count */
|
|
|
|
current = (unsigned char *)buf + sizeof(HEADER);
|
|
if (header->qdcount != 1)
|
|
return 0;
|
|
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf,
|
|
sizeof(hostbuf));
|
|
if (n <= 0)
|
|
return 0;
|
|
if (strcasecmp(hostbuf, request->queryname))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* proc_answer - process name server reply
|
|
*/
|
|
static int proc_answer(struct reslist *request, HEADER * header, char *buf, char *eob)
|
|
{
|
|
char hostbuf[IRCD_RES_HOSTLEN + 100]; /* working buffer */
|
|
unsigned char *current; /* current position in buf */
|
|
int type; /* answer type */
|
|
int n; /* temp count */
|
|
int rd_length;
|
|
struct sockaddr_in *v4; /* conversion */
|
|
#ifdef RB_IPV6
|
|
struct sockaddr_in6 *v6;
|
|
#endif
|
|
current = (unsigned char *)buf + sizeof(HEADER);
|
|
|
|
for (; header->qdcount > 0; --header->qdcount)
|
|
{
|
|
if ((n = irc_dn_skipname(current, (unsigned char *)eob)) < 0)
|
|
return 0;
|
|
|
|
current += (size_t) n + QFIXEDSZ;
|
|
}
|
|
|
|
/*
|
|
* process each answer sent to us blech.
|
|
*/
|
|
while (header->ancount > 0 && (char *)current < eob)
|
|
{
|
|
header->ancount--;
|
|
|
|
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current, hostbuf,
|
|
sizeof(hostbuf));
|
|
|
|
if (n < 0)
|
|
{
|
|
/*
|
|
* broken message
|
|
*/
|
|
return (0);
|
|
}
|
|
else if (n == 0)
|
|
{
|
|
/*
|
|
* no more answers left
|
|
*/
|
|
return (0);
|
|
}
|
|
|
|
hostbuf[IRCD_RES_HOSTLEN] = '\0';
|
|
|
|
/* With Address arithmetic you have to be very anal
|
|
* this code was not working on alpha due to that
|
|
* (spotted by rodder/jailbird/dianora)
|
|
*/
|
|
current += (size_t) n;
|
|
|
|
if (!(((char *)current + ANSWER_FIXED_SIZE) < eob))
|
|
break;
|
|
|
|
type = irc_ns_get16(current);
|
|
current += TYPE_SIZE;
|
|
|
|
(void) irc_ns_get16(current);
|
|
current += CLASS_SIZE;
|
|
|
|
request->ttl = irc_ns_get32(current);
|
|
current += TTL_SIZE;
|
|
|
|
rd_length = irc_ns_get16(current);
|
|
current += RDLENGTH_SIZE;
|
|
|
|
/*
|
|
* Wait to set request->type until we verify this structure
|
|
*/
|
|
switch (type)
|
|
{
|
|
case T_A:
|
|
if (request->type != T_A)
|
|
return (0);
|
|
|
|
/*
|
|
* check for invalid rd_length or too many addresses
|
|
*/
|
|
if (rd_length != sizeof(struct in_addr))
|
|
return (0);
|
|
v4 = (struct sockaddr_in *)&request->addr;
|
|
SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in));
|
|
v4->sin_family = AF_INET;
|
|
memcpy(&v4->sin_addr, current, sizeof(struct in_addr));
|
|
return (1);
|
|
break;
|
|
#ifdef RB_IPV6
|
|
case T_AAAA:
|
|
if (request->type != T_AAAA)
|
|
return (0);
|
|
if (rd_length != sizeof(struct in6_addr))
|
|
return (0);
|
|
SET_SS_LEN(&request->addr, sizeof(struct sockaddr_in6));
|
|
v6 = (struct sockaddr_in6 *)&request->addr;
|
|
v6->sin6_family = AF_INET6;
|
|
memcpy(&v6->sin6_addr, current, sizeof(struct in6_addr));
|
|
return (1);
|
|
break;
|
|
#endif
|
|
case T_PTR:
|
|
if (request->type != T_PTR)
|
|
return (0);
|
|
n = irc_dn_expand((unsigned char *)buf, (unsigned char *)eob, current,
|
|
hostbuf, sizeof(hostbuf));
|
|
if (n < 0)
|
|
return (0); /* broken message */
|
|
else if (n == 0)
|
|
return (0); /* no more answers left */
|
|
|
|
rb_strlcpy(request->name, hostbuf, IRCD_RES_HOSTLEN + 1);
|
|
|
|
return (1);
|
|
break;
|
|
case T_CNAME:
|
|
/* real answer will follow */
|
|
current += rd_length;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
return (1);
|
|
}
|
|
|
|
/*
|
|
* res_read_single_reply - read a dns reply from the nameserver and process it.
|
|
* Return value: 1 if a packet was read, 0 otherwise
|
|
*/
|
|
static int res_read_single_reply(rb_fde_t *F, void *data)
|
|
{
|
|
char buf[sizeof(HEADER) + MAXPACKET]
|
|
/* Sparc and alpha need 16bit-alignment for accessing header->id
|
|
* (which is uint16_t). Because of the header = (HEADER*) buf;
|
|
* lateron, this is neeeded. --FaUl
|
|
*/
|
|
#if defined(__sparc__) || defined(__alpha__)
|
|
__attribute__ ((aligned(16)))
|
|
#endif
|
|
;
|
|
HEADER *header;
|
|
struct reslist *request = NULL;
|
|
struct DNSReply *reply = NULL;
|
|
int rc;
|
|
int answer_count;
|
|
socklen_t len = sizeof(struct rb_sockaddr_storage);
|
|
struct rb_sockaddr_storage lsin;
|
|
int ns;
|
|
|
|
rc = recvfrom(rb_get_fd(F), buf, sizeof(buf), 0, (struct sockaddr *)&lsin, &len);
|
|
|
|
/* No packet */
|
|
if (rc == 0 || rc == -1)
|
|
return 0;
|
|
|
|
/* Too small */
|
|
if (rc <= (int)(sizeof(HEADER)))
|
|
return 1;
|
|
|
|
/*
|
|
* convert DNS reply reader from Network byte order to CPU byte order.
|
|
*/
|
|
header = (HEADER *)(void *)buf;
|
|
header->ancount = ntohs(header->ancount);
|
|
header->qdcount = ntohs(header->qdcount);
|
|
header->nscount = ntohs(header->nscount);
|
|
header->arcount = ntohs(header->arcount);
|
|
|
|
/*
|
|
* response for an id which we have already received an answer for
|
|
* just ignore this response.
|
|
*/
|
|
if (0 == (request = find_id(header->id)))
|
|
return 1;
|
|
|
|
/*
|
|
* check against possibly fake replies
|
|
*/
|
|
ns = res_ourserver(&lsin);
|
|
if (ns == -1)
|
|
return 1;
|
|
|
|
if (ns != request->lastns)
|
|
{
|
|
/*
|
|
* We'll accept the late reply, but penalize it a little more to make
|
|
* sure a laggy server doesn't end up favored.
|
|
*/
|
|
ns_failure_count[ns] += 3;
|
|
}
|
|
|
|
|
|
if (!check_question(request, header, buf, buf + rc))
|
|
return 1;
|
|
|
|
if ((header->rcode != NO_ERRORS) || (header->ancount == 0))
|
|
{
|
|
/*
|
|
* RFC 2136 states that in the event of a server returning SERVFAIL
|
|
* or NOTIMP, the request should be resent to the next server.
|
|
* Additionally, if the server refuses our query, resend it as well.
|
|
* -- mr_flea
|
|
*/
|
|
if (SERVFAIL == header->rcode || NOTIMP == header->rcode ||
|
|
REFUSED == header->rcode)
|
|
{
|
|
ns_failure_count[ns]++;
|
|
resend_query(request);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Either a fatal error was returned or no answer. Cancel the
|
|
* request.
|
|
*/
|
|
if (NXDOMAIN == header->rcode)
|
|
{
|
|
/* If the rcode is NXDOMAIN, treat it as a good response. */
|
|
ns_failure_count[ns] /= 4;
|
|
}
|
|
(*request->query->callback) (request->query->ptr, NULL);
|
|
rem_request(request);
|
|
}
|
|
return 1;
|
|
}
|
|
/*
|
|
* If this fails there was an error decoding the received packet.
|
|
* -- jilles
|
|
*/
|
|
answer_count = proc_answer(request, header, buf, buf + rc);
|
|
|
|
if (answer_count)
|
|
{
|
|
if (request->type == T_PTR)
|
|
{
|
|
if (request->name == NULL)
|
|
{
|
|
/*
|
|
* Got a PTR response with no name, something strange is
|
|
* happening. Try another DNS server.
|
|
*/
|
|
ns_failure_count[ns]++;
|
|
resend_query(request);
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Lookup the 'authoritative' name that we were given for the
|
|
* ip#.
|
|
*/
|
|
#ifdef RB_IPV6
|
|
if (GET_SS_FAMILY(&request->addr) == AF_INET6)
|
|
gethost_byname_type_fqdn(request->name, request->query, T_AAAA);
|
|
else
|
|
#endif
|
|
gethost_byname_type_fqdn(request->name, request->query, T_A);
|
|
rem_request(request);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* got a name and address response, client resolved
|
|
*/
|
|
reply = make_dnsreply(request);
|
|
(*request->query->callback) (request->query->ptr, reply);
|
|
rb_free(reply);
|
|
rem_request(request);
|
|
}
|
|
|
|
ns_failure_count[ns] /= 4;
|
|
}
|
|
else
|
|
{
|
|
/* Invalid or corrupt reply - try another resolver. */
|
|
ns_failure_count[ns]++;
|
|
resend_query(request);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static void
|
|
res_readreply(rb_fde_t *F, void *data)
|
|
{
|
|
while (res_read_single_reply(F, data))
|
|
;
|
|
rb_setselect(F, RB_SELECT_READ, res_readreply, NULL);
|
|
}
|
|
|
|
static struct DNSReply *
|
|
make_dnsreply(struct reslist *request)
|
|
{
|
|
struct DNSReply *cp;
|
|
lrb_assert(request != 0);
|
|
|
|
cp = (struct DNSReply *)rb_malloc(sizeof(struct DNSReply));
|
|
|
|
cp->h_name = request->name;
|
|
memcpy(&cp->addr, &request->addr, sizeof(cp->addr));
|
|
return (cp);
|
|
}
|