/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
- * Copyright 1998-2013 The OpenLDAP Foundation.
+ * Copyright 1998-2015 The OpenLDAP Foundation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
return LDAP_SUCCESS;
}
+#ifdef HAVE_RES_QUERY
+#define DNSBUFSIZ (64*1024)
+#define MAXHOST 254 /* RFC 1034, max length is 253 chars */
+typedef struct srv_record {
+ u_short priority;
+ u_short weight;
+ u_short port;
+ char hostname[MAXHOST];
+} srv_record;
+
+/* Linear Congruential Generator - we don't need
+ * high quality randomness, and we don't want to
+ * interfere with anyone else's use of srand().
+ *
+ * The PRNG here cycles thru 941,955 numbers.
+ */
+static float srv_seed;
+
+static void srv_srand(int seed) {
+ srv_seed = (float)seed / (float)RAND_MAX;
+}
+
+static float srv_rand() {
+ float val = 9821.0 * srv_seed + .211327;
+ srv_seed = val - (int)val;
+ return srv_seed;
+}
+
+static int srv_cmp(const void *aa, const void *bb){
+ srv_record *a=(srv_record *)aa;
+ srv_record *b=(srv_record *)bb;
+ int i = a->priority - b->priority;
+ if (i) return i;
+ return b->weight - a->weight;
+}
+
+static void srv_shuffle(srv_record *a, int n) {
+ int i, j, total = 0, r, p;
+
+ for (i=0; i<n; i++)
+ total += a[i].weight;
+
+ /* all weights are zero, do a straight Fisher-Yates shuffle */
+ if (!total) {
+ while (n) {
+ srv_record t;
+ i = srv_rand() * n--;
+ t = a[n];
+ a[n] = a[i];
+ a[i] = t;
+ }
+ return;
+ }
+
+ /* Do a shuffle per RFC2782 Page 4 */
+ p = n;
+ for (i=0; i<n-1; i++) {
+ r = srv_rand() * total;
+ for (j=0; j<p; j++) {
+ r -= a[j].weight;
+ if (r <= 0) {
+ if (j) {
+ srv_record t = a[0];
+ a[0] = a[j];
+ a[j] = t;
+ }
+ total -= a[0].weight;
+ a++;
+ p--;
+ break;
+ }
+ }
+ }
+}
+#endif /* HAVE_RES_QUERY */
+
/*
* Lookup and return LDAP servers for domain (using the DNS
* SRV record _ldap._tcp.domain).
char **list )
{
#ifdef HAVE_RES_QUERY
-#define DNSBUFSIZ (64*1024)
char *request;
char *hostlist = NULL;
+ srv_record *hostent_head=NULL;
+ int i, j;
int rc, len, cur = 0;
unsigned char reply[DNSBUFSIZ];
+ int hostent_count=0;
assert( domain != NULL );
assert( list != NULL );
-
if( *domain == '\0' ) {
return LDAP_PARAM_ERROR;
}
unsigned char *p;
char host[DNSBUFSIZ];
int status;
- u_short port;
- /* int priority, weight; */
+ u_short port, priority, weight;
/* Parse out query */
p = reply;
size = (p[0] << 8) | p[1];
p += 2;
if (type == T_SRV) {
- int buflen;
status = dn_expand(reply, reply + len, p + 6, host, sizeof(host));
if (status < 0) {
goto out;
}
- /* ignore priority and weight for now */
- /* priority = (p[0] << 8) | p[1]; */
- /* weight = (p[2] << 8) | p[3]; */
+
+ /* Get priority weight and port */
+ priority = (p[0] << 8) | p[1];
+ weight = (p[2] << 8) | p[3];
port = (p[4] << 8) | p[5];
if ( port == 0 || host[ 0 ] == '\0' ) {
goto add_size;
}
- buflen = strlen(host) + STRLENOF(":65355 ");
- hostlist = (char *) LDAP_REALLOC(hostlist, cur + buflen + 1);
- if (hostlist == NULL) {
- rc = LDAP_NO_MEMORY;
+ hostent_head = (srv_record *) LDAP_REALLOC(hostent_head, (hostent_count+1)*(sizeof(srv_record)));
+ if(hostent_head==NULL){
+ rc=LDAP_NO_MEMORY;
goto out;
}
- if (cur > 0) {
- /* not first time around */
- hostlist[cur++] = ' ';
- }
- cur += sprintf(&hostlist[cur], "%s:%hu", host, port);
+ hostent_head[hostent_count].priority=priority;
+ hostent_head[hostent_count].weight=weight;
+ hostent_head[hostent_count].port=port;
+ strncpy(hostent_head[hostent_count].hostname, host, MAXHOST-1);
+ hostent_head[hostent_count].hostname[MAXHOST-1] = '\0';
+ hostent_count++;
}
add_size:;
p += size;
}
+ if (!hostent_head) goto out;
+ qsort(hostent_head, hostent_count, sizeof(srv_record), srv_cmp);
+
+ if (!srv_seed)
+ srv_srand(time(0L));
+
+ /* shuffle records of same priority */
+ j = 0;
+ priority = hostent_head[0].priority;
+ for (i=1; i<hostent_count; i++) {
+ if (hostent_head[i].priority != priority) {
+ priority = hostent_head[i].priority;
+ if (i-j > 1)
+ srv_shuffle(hostent_head+j, i-j);
+ j = i;
+ }
+ }
+ if (i-j > 1)
+ srv_shuffle(hostent_head+j, i-j);
+
+ for(i=0; i<hostent_count; i++){
+ int buflen;
+ buflen = strlen(hostent_head[i].hostname) + STRLENOF(":65535 ");
+ hostlist = (char *) LDAP_REALLOC(hostlist, cur+buflen+1);
+ if (hostlist == NULL) {
+ rc = LDAP_NO_MEMORY;
+ goto out;
+ }
+ if(cur>0){
+ hostlist[cur++]=' ';
+ }
+ cur += sprintf(&hostlist[cur], "%s:%hd", hostent_head[i].hostname, hostent_head[i].port);
+ }
}
+
if (hostlist == NULL) {
/* No LDAP servers found in DNS. */
rc = LDAP_UNAVAILABLE;
if (request != NULL) {
LDAP_FREE(request);
}
+ if (hostent_head != NULL) {
+ LDAP_FREE(hostent_head);
+ }
if (rc != LDAP_SUCCESS && hostlist != NULL) {
LDAP_FREE(hostlist);
}
projects / openldap / blobdiff