dns_srv_order to order srv records
git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@10039 ec53bebd-3082-4978-b11e-865c3cabbd6b
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@@ -1,5 +1,5 @@
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/*
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* Copyright (c) 1995 - 2000 Kungliga Tekniska H<>gskolan
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* Copyright (c) 1995 - 2001 Kungliga Tekniska H<>gskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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@@ -43,6 +43,8 @@
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#endif
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#include "resolve.h"
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#include <assert.h>
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RCSID("$Id$");
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#if defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND)
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@@ -360,6 +362,109 @@ dns_lookup(const char *domain, const char *type_name)
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return dns_lookup_int(domain, C_IN, type);
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}
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static int
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compare_srv(const void *a, const void *b)
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{
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const struct resource_record *const* aa = a, *const* bb = b;
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if((*aa)->u.srv->priority == (*bb)->u.srv->priority)
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return ((*aa)->u.srv->weight - (*bb)->u.srv->weight);
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return ((*aa)->u.srv->priority - (*bb)->u.srv->priority);
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}
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#ifndef HAVE_RANDOM
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#define random() rand()
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#endif
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/* try to rearrange the srv-records by the algorithm in RFC2782 */
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void
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dns_srv_order(struct dns_reply *r)
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{
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struct resource_record **srvs, **ss, **headp;
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struct resource_record *rr;
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int num_srv = 0;
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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char state[256], *oldstate;
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#endif
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for(rr = r->head; rr; rr = rr->next)
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if(rr->type == T_SRV)
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num_srv++;
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if(num_srv == 0)
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return;
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srvs = malloc(num_srv * sizeof(*srvs));
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if(srvs == NULL)
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return; /* XXX not much to do here */
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/* unlink all srv-records from the linked list and put them in
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a vector */
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for(ss = srvs, headp = &r->head; *headp; )
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if((*headp)->type == T_SRV) {
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*ss = *headp;
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*headp = (*headp)->next;
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(*ss)->next = NULL;
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ss++;
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} else
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headp = &(*headp)->next;
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/* sort them by priority and weight */
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qsort(srvs, num_srv, sizeof(*srvs), compare_srv);
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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oldstate = initstate(time(NULL), state, sizeof(state));
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#endif
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headp = &r->head;
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for(ss = srvs; ss < srvs + num_srv; ) {
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int sum, rnd, count;
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struct resource_record **ee, **tt;
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/* find the last record with the same priority and count the
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sum of all weights */
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for(sum = 0, tt = ss; tt < srvs + num_srv; tt++) {
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if(*tt == NULL)
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continue;
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if((*tt)->u.srv->priority != (*ss)->u.srv->priority)
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break;
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sum += (*tt)->u.srv->weight;
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}
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ee = tt;
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/* ss is now the first record of this priority and ee is the
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first of the next */
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while(ss < ee) {
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rnd = random() % (sum + 1);
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for(count = 0, tt = ss; ; tt++) {
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if(*tt == NULL)
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continue;
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count += (*tt)->u.srv->weight;
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if(count >= rnd)
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break;
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}
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assert(tt < ee);
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/* insert the selected record at the tail (of the head) of
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the list */
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(*tt)->next = *headp;
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*headp = *tt;
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headp = &(*tt)->next;
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sum -= (*tt)->u.srv->weight;
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*tt = NULL;
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while(*ss == NULL)
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ss++;
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}
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}
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#if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
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setstate(oldstate);
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#endif
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free(srvs);
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return;
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}
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#else /* NOT defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND) */
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struct dns_reply *
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@@ -373,6 +478,12 @@ dns_free_data(struct dns_reply *r)
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{
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}
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int
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dns_srv_order(struct dns_reply *r)
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{
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return 0;
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}
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#endif
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#ifdef TEST
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@@ -386,6 +497,9 @@ main(int argc, char **argv)
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printf("No reply.\n");
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return 1;
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}
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if(r->q.type == T_SRV)
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dns_srv_order(r);
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for(rr = r->head; rr;rr=rr->next){
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printf("%s %s %d ", rr->domain, dns_type_to_string(rr->type), rr->ttl);
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switch(rr->type){
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@@ -1,5 +1,5 @@
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/*
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* Copyright (c) 1995 - 2000 Kungliga Tekniska H<>gskolan
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* Copyright (c) 1995 - 2001 Kungliga Tekniska H<>gskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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@@ -142,5 +142,6 @@ struct dns_reply* dns_lookup(const char *, const char *);
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void dns_free_data(struct dns_reply *);
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int dns_string_to_type(const char *name);
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const char *dns_type_to_string(int type);
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void dns_srv_order(struct dns_reply*);
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#endif /* __RESOLVE_H__ */
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