mirror of
https://github.com/matrix-construct/construct
synced 2024-10-30 02:18:58 +01:00
3f6cbacc41
The random_socket function isn't used, and the code can only be compiled if the function is optimised away (because it's static and unused) otherwise it will fail to link when "ipv4_addr" and "ipv6_addr" are not found. Fix this by modifying ipv4_addr and ipv6_addr so that they're not external variables.
972 lines
24 KiB
C
972 lines
24 KiB
C
/*
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* A rewrite of Darren Reeds original res.c As there is nothing
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* left of Darrens original code, this is now licensed by the hybrid group.
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* (Well, some of the function names are the same, and bits of the structs..)
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* You can use it where it is useful, free even. Buy us a beer and stuff.
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*
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* The authors takes no responsibility for any damage or loss
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* of property which results from the use of this software.
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*
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* $Id: res.c 3301 2007-03-28 15:04:06Z jilles $
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* from Hybrid Id: res.c 459 2006-02-12 22:21:37Z db $
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*
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* July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
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* added callbacks and reference counting of returned hostents.
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* --Bleep (Thomas Helvey <tomh@inxpress.net>)
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*
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* This was all needlessly complicated for irc. Simplified. No more hostent
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* All we really care about is the IP -> hostname mappings. Thats all.
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*
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* Apr 28, 2003 --cryogen and Dianora
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*
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* DNS server flooding lessened, AAAA-or-A lookup removed, ip6.int support
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* removed, various robustness fixes
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*
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* 2006 --jilles and nenolod
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*
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* Resend queries to other servers if the DNS server replies with an error or
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* an invalid response. Also, avoid servers that return errors or invalid
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* responses.
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*
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* October 2012 --mr_flea
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*
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* ircd-ratbox changes for random IDs merged back in.
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*
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* January 2016 --kaniini
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*/
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#include <ratbox_lib.h>
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#include "setup.h"
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#include "res.h"
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#include "reslib.h"
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#if (CHAR_BIT != 8)
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#error this code needs to be able to address individual octets
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#endif
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static PF res_readreply;
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#define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
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#define RES_MAXALIASES 35 /* maximum aliases allowed */
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#define RES_MAXADDRS 35 /* maximum addresses allowed */
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#define AR_TTL 600 /* TTL in seconds for dns cache entries */
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/* RFC 1104/1105 wasn't very helpful about what these fields
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* should be named, so for now, we'll just name them this way.
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* we probably should look at what named calls them or something.
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*/
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#define TYPE_SIZE (size_t)2
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#define CLASS_SIZE (size_t)2
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#define TTL_SIZE (size_t)4
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#define RDLENGTH_SIZE (size_t)2
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#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
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#ifdef RB_IPV6
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struct in6_addr ipv6_addr;
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#endif
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struct in_addr ipv4_addr;
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struct reslist
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{
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rb_dlink_node node;
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int id;
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time_t ttl;
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char type;
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char queryname[IRCD_RES_HOSTLEN + 1]; /* name currently being queried */
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char retries; /* retry counter */
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char sends; /* number of sends (>1 means resent) */
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time_t sentat;
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time_t timeout;
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int lastns; /* index of last server sent to */
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struct rb_sockaddr_storage addr;
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char *name;
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struct DNSQuery *query; /* query callback for this request */
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};
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static rb_fde_t *res_fd;
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static rb_dlink_list request_list = { NULL, NULL, 0 };
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static int ns_failure_count[IRCD_MAXNS]; /* timeouts and invalid/failed replies */
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static void rem_request(struct reslist *request);
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static struct reslist *make_request(struct DNSQuery *query);
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static void gethost_byname_type_fqdn(const char *name, struct DNSQuery *query,
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int type);
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static void do_query_name(struct DNSQuery *query, const char *name, struct reslist *request, int);
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static void do_query_number(struct DNSQuery *query, const struct rb_sockaddr_storage *,
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struct reslist *request);
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static void query_name(struct reslist *request);
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static int send_res_msg(const char *buf, int len, int count);
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static void resend_query(struct reslist *request);
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static int check_question(struct reslist *request, HEADER * header, char *buf, char *eob);
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static int proc_answer(struct reslist *request, HEADER * header, char *, char *);
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static struct reslist *find_id(int id);
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static struct DNSReply *make_dnsreply(struct reslist *request);
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static int generate_random_port(void);
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static uint16_t generate_random_id(void);
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#ifdef RES_MIN
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#undef RES_MIN
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#endif
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#define RES_MIN(a, b) ((a) < (b) ? (a) : (b))
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static rb_fde_t *
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random_socket(int family)
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{
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rb_fde_t *F;
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int nport;
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int i;
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rb_socklen_t len;
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struct rb_sockaddr_storage sockaddr;
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F = rb_socket(family, SOCK_DGRAM, 0, "UDP resolver socket");
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if(F == NULL)
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return NULL;
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memset(&sockaddr, 0, sizeof(sockaddr));
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SET_SS_FAMILY(&sockaddr, family);
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#ifdef RB_IPV6
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if(family == AF_INET6)
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{
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struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)&sockaddr;
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memcpy(&in6->sin6_addr, &ipv6_addr, sizeof(struct in6_addr));
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len = (rb_socklen_t) sizeof(struct sockaddr_in6);
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}
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else
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#endif
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{
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struct sockaddr_in *in = (struct sockaddr_in *)&sockaddr;
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in->sin_addr.s_addr = ipv4_addr.s_addr;
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len = (rb_socklen_t) sizeof(struct sockaddr_in);
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}
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for(i = 0; i < 10; i++)
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{
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nport = htons(generate_random_port());
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if(family == AF_INET)
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((struct sockaddr_in *)&sockaddr)->sin_port = nport;
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#ifdef RB_IPV6
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else
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((struct sockaddr_in6 *)&sockaddr)->sin6_port = nport;
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#endif
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if(bind(rb_get_fd(F), (struct sockaddr *)&sockaddr, len) == 0)
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return F;
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}
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rb_close(F);
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return NULL;
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}
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/*
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* int
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* res_ourserver(inp)
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* looks up "inp" in irc_nsaddr_list[]
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* returns:
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* server ID or -1 for not found
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* author:
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* paul vixie, 29may94
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* revised for ircd, cryogen(stu) may03
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* slightly modified for charybdis, mr_flea oct12
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*/
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static int res_ourserver(const struct rb_sockaddr_storage *inp)
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{
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#ifdef RB_IPV6
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const struct sockaddr_in6 *v6;
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const struct sockaddr_in6 *v6in = (const struct sockaddr_in6 *)inp;
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#endif
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const struct sockaddr_in *v4;
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const struct sockaddr_in *v4in = (const struct sockaddr_in *)inp;
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int ns;
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for (ns = 0; ns < irc_nscount; ns++)
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{
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const struct rb_sockaddr_storage *srv = &irc_nsaddr_list[ns];
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if (srv->ss_family != inp->ss_family)
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continue;
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#ifdef RB_IPV6
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v6 = (const struct sockaddr_in6 *)srv;
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#endif
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v4 = (const struct sockaddr_in *)srv;
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/* could probably just memcmp(srv, inp, srv.ss_len) here
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* but we'll err on the side of caution - stu
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*/
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switch (srv->ss_family)
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{
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#ifdef RB_IPV6
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case AF_INET6:
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if (v6->sin6_port == v6in->sin6_port)
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if ((memcmp(&v6->sin6_addr.s6_addr, &v6in->sin6_addr.s6_addr,
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sizeof(struct in6_addr)) == 0) ||
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(memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
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sizeof(struct in6_addr)) == 0))
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{
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return ns;
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}
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break;
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#endif
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case AF_INET:
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if (v4->sin_port == v4in->sin_port)
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if ((v4->sin_addr.s_addr == INADDR_ANY)
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|| (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
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{
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return ns;
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}
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break;
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default:
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break;
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}
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}
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return -1;
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}
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/*
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* timeout_query_list - Remove queries from the list which have been
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* there too long without being resolved.
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*/
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static time_t timeout_query_list(time_t now)
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{
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rb_dlink_node *ptr;
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rb_dlink_node *next_ptr;
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struct reslist *request;
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time_t next_time = 0;
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time_t timeout = 0;
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RB_DLINK_FOREACH_SAFE(ptr, next_ptr, request_list.head)
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{
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request = ptr->data;
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timeout = request->sentat + request->timeout;
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if (now >= timeout)
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{
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ns_failure_count[request->lastns]++;
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request->sentat = now;
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request->timeout += request->timeout;
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resend_query(request);
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}
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if ((next_time == 0) || timeout < next_time)
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{
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next_time = timeout;
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}
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}
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return (next_time > now) ? next_time : (now + AR_TTL);
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}
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/*
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* timeout_resolver - check request list
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*/
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static void timeout_resolver(void *notused)
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{
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timeout_query_list(rb_current_time());
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}
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static struct ev_entry *timeout_resolver_ev = NULL;
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/*
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* start_resolver - do everything we need to read the resolv.conf file
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* and initialize the resolver file descriptor if needed
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*/
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static void start_resolver(void)
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{
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int i;
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irc_res_init();
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for (i = 0; i < irc_nscount; i++)
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ns_failure_count[i] = 0;
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if (res_fd == NULL)
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{
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if ((res_fd = rb_socket(irc_nsaddr_list[0].ss_family, SOCK_DGRAM, 0,
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"UDP resolver socket")) == NULL)
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return;
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/* At the moment, the resolver FD data is global .. */
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rb_setselect(res_fd, RB_SELECT_READ, res_readreply, NULL);
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timeout_resolver_ev = rb_event_add("timeout_resolver", timeout_resolver, NULL, 1);
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}
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}
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/*
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* init_resolver - initialize resolver and resolver library
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*/
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void init_resolver(void)
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{
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#ifdef HAVE_SRAND48
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srand48(rb_current_time());
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#endif
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start_resolver();
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}
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/*
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* restart_resolver - reread resolv.conf, reopen socket
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*/
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void restart_resolver(void)
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{
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rb_close(res_fd);
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res_fd = NULL;
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rb_event_delete(timeout_resolver_ev); /* -ddosen */
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start_resolver();
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}
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/*
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* add_local_domain - Add the domain to hostname, if it is missing
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* (as suggested by eps@TOASTER.SFSU.EDU)
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*/
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void add_local_domain(char *hname, size_t size)
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{
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/* try to fix up unqualified names */
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if (strchr(hname, '.') == NULL)
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{
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if (irc_domain[0])
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{
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size_t len = strlen(hname);
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if ((strlen(irc_domain) + len + 2) < size)
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{
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hname[len++] = '.';
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strcpy(hname + len, irc_domain);
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}
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}
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}
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}
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/*
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* rem_request - remove a request from the list.
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* This must also free any memory that has been allocated for
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* temporary storage of DNS results.
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*/
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static void rem_request(struct reslist *request)
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{
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rb_dlinkDelete(&request->node, &request_list);
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rb_free(request->name);
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rb_free(request);
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}
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/*
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* make_request - Create a DNS request record for the server.
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*/
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static struct reslist *make_request(struct DNSQuery *query)
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{
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struct reslist *request = rb_malloc(sizeof(struct reslist));
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request->sentat = rb_current_time();
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request->retries = 3;
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request->timeout = 4; /* start at 4 and exponential inc. */
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request->query = query;
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/*
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* generate a unique id
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* NOTE: we don't have to worry about converting this to and from
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* network byte order, the nameserver does not interpret this value
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* and returns it unchanged
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*
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* we generate an id per request now (instead of per send) to allow
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* late replies to be used.
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*/
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request->id = generate_random_id();
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rb_dlinkAdd(request, &request->node, &request_list);
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return request;
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}
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/*
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* retryfreq - determine how many queries to wait before resending
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* if there have been that many consecutive timeouts
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*/
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static int retryfreq(int timeouts)
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{
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switch (timeouts)
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{
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case 1:
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return 3;
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case 2:
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return 9;
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case 3:
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return 27;
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case 4:
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return 81;
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default:
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return 243;
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}
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}
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/*
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* send_res_msg - sends msg to a nameserver.
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* This should reflect /etc/resolv.conf.
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* Returns number of nameserver successfully sent to
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* or -1 if no successful sends.
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*/
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static int send_res_msg(const char *msg, int len, int rcount)
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{
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int i;
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int ns;
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static int retrycnt;
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retrycnt++;
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/* First try a nameserver that seems to work.
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* Every once in a while, try a possibly broken one to check
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* if it is working again.
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*/
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for (i = 0; i < irc_nscount; i++)
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{
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ns = (i + rcount - 1) % irc_nscount;
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if (ns_failure_count[ns] && retrycnt % retryfreq(ns_failure_count[ns]))
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continue;
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if (sendto(rb_get_fd(res_fd), msg, len, 0,
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(struct sockaddr *)&(irc_nsaddr_list[ns]),
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GET_SS_LEN(&irc_nsaddr_list[ns])) == len)
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return ns;
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}
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/* No known working nameservers, try some broken one. */
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for (i = 0; i < irc_nscount; i++)
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{
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ns = (i + rcount - 1) % irc_nscount;
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if (!ns_failure_count[ns])
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continue;
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if (sendto(rb_get_fd(res_fd), msg, len, 0,
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(struct sockaddr *)&(irc_nsaddr_list[ns]),
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GET_SS_LEN(&irc_nsaddr_list[ns])) == len)
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return ns;
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}
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return -1;
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}
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|
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/*
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* find_id - find a dns request id (id is determined by dn_mkquery)
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*/
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static struct reslist *find_id(int id)
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{
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rb_dlink_node *ptr;
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struct reslist *request;
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RB_DLINK_FOREACH(ptr, request_list.head)
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{
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request = ptr->data;
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if (request->id == id)
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return (request);
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}
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return (NULL);
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}
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|
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static uint16_t
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generate_random_id(void)
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{
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uint16_t id;
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|
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do
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{
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rb_get_random(&id, sizeof(id));
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if(id == 0xffff)
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continue;
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}
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while(find_id(id));
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return id;
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}
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|
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static int
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generate_random_port(void)
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{
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uint16_t port;
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|
|
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while(1)
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{
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rb_get_random(&port, sizeof(port));
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if(port > 1024)
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break;
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}
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return (int)port;
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}
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|
|
|
/*
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|
* gethost_byname_type - get host address from name, adding domain if needed
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|
*/
|
|
void gethost_byname_type(const char *name, struct DNSQuery *query, int type)
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|
{
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char fqdn[IRCD_RES_HOSTLEN + 1];
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assert(name != 0);
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rb_strlcpy(fqdn, name, sizeof fqdn);
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add_local_domain(fqdn, IRCD_RES_HOSTLEN);
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gethost_byname_type_fqdn(fqdn, query, type);
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}
|
|
|
|
/*
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* gethost_byname_type_fqdn - get host address from fqdn
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|
*/
|
|
static void gethost_byname_type_fqdn(const char *name, struct DNSQuery *query,
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int type)
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{
|
|
assert(name != 0);
|
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do_query_name(query, name, NULL, type);
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|
}
|
|
|
|
/*
|
|
* gethost_byaddr - get host name from address
|
|
*/
|
|
void gethost_byaddr(const struct rb_sockaddr_storage *addr, struct DNSQuery *query)
|
|
{
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|
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);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
const unsigned char *cp;
|
|
|
|
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);
|
|
}
|
|
|
|
if (addr->ss_family == AF_INET)
|
|
{
|
|
const struct sockaddr_in *v4 = (const struct sockaddr_in *)addr;
|
|
cp = (const unsigned char *)&v4->sin_addr.s_addr;
|
|
|
|
sprintf(request->queryname, "%u.%u.%u.%u.in-addr.arpa", (unsigned int)(cp[3]),
|
|
(unsigned int)(cp[2]), (unsigned int)(cp[1]), (unsigned int)(cp[0]));
|
|
}
|
|
#ifdef RB_IPV6
|
|
else if (addr->ss_family == AF_INET6)
|
|
{
|
|
const struct sockaddr_in6 *v6 = (const struct sockaddr_in6 *)addr;
|
|
cp = (const unsigned char *)&v6->sin6_addr.s6_addr;
|
|
|
|
(void)sprintf(request->queryname, "%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.ip6.arpa",
|
|
(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));
|
|
}
|
|
#endif
|
|
|
|
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 (request->addr.ss_family == 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);
|
|
}
|