openldap/sme9/openldap-dns-priority.patch

Implement priority/weight for DNS SRV records

From RFC 2782:

  A client MUST attempt to contact the target host with the
  lowest-numbered priority it can reach.

This patch sorts the DNS SRV records by their priority, and
additionally gives records with a larger weight a higher probability
of appearing earlier. This way, the DNS SRV records are tried in the
order of their priority.

Author: James M Leddy <james.leddy@redhat.com>
Upstream ITS: #7027
Resolves: #733078

---
 libraries/libldap/dnssrv.c |  106 ++++++++++++++++++++++++++++++++++----------
 1 files changed, 83 insertions(+), 23 deletions(-)

diff --git a/libraries/libldap/dnssrv.c b/libraries/libldap/dnssrv.c
index 16b1544..40f93b4 100644
--- a/libraries/libldap/dnssrv.c
+++ b/libraries/libldap/dnssrv.c
@@ -174,6 +174,46 @@ int ldap_domain2dn(
        return LDAP_SUCCESS;
 }
 
+#ifdef HAVE_RES_QUERY
+#define DNSBUFSIZ (64*1024)
+typedef struct srv_record {
+    u_short priority;
+    u_short weight;
+    u_short port;
+    char hostname[DNSBUFSIZ];
+} srv_record;
+
+
+static int srv_cmp(const void *aa, const void *bb){
+    srv_record *a=(srv_record *)aa;
+    srv_record *b=(srv_record *)bb;
+    u_long total;
+    
+    if(a->priority < b->priority) {
+       return -1;
+    }
+    if(a->priority > b->priority) {
+       return 1;
+    }
+    if(a->priority == b->priority){
+       /* targets with same priority are in psudeo random order */
+       if (a->weight == 0 && b->weight == 0) {
+           if (rand() % 2) {
+               return -1;
+           } else {
+               return 1;
+           }
+       }
+       total = a->weight + b->weight;
+       if (rand() % total < a->weight) {
+           return -1;
+       } else {
+           return 1;
+       }
+    }
+}
+#endif /* HAVE_RES_QUERY */
+
 /*
  * Lookup and return LDAP servers for domain (using the DNS
  * SRV record _ldap._tcp.domain).
@@ -183,15 +223,16 @@ int ldap_domain2hostlist(
        char **list )
 {
 #ifdef HAVE_RES_QUERY
-#define DNSBUFSIZ (64*1024)
-    char *request;
-    char *hostlist = NULL;
+    char *request; 
+   char *hostlist = NULL;
+    srv_record *hostent_head=NULL;
+    int i;
     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;
        }
@@ -223,8 +264,7 @@ int ldap_domain2hostlist(
        unsigned char *p;
        char host[DNSBUFSIZ];
        int status;
-       u_short port;
-       /* int priority, weight; */
+       u_short port, priority, weight; 
 
        /* Parse out query */
        p = reply;
@@ -263,40 +303,56 @@ int ldap_domain2hostlist(
            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;
-                   goto out;
+               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,255);
+               hostent_count=hostent_count+1;
            }
 add_size:;
            p += size;
        }
     }
+    qsort(hostent_head, hostent_count, sizeof(srv_record), srv_cmp);
+
+    for(i=0; i<hostent_count; i++){
+       int buflen;
+        buflen = strlen(hostent_head[i].hostname) + STRLENOF(":65355" );
+        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;
-       goto out;
+         /* No LDAP servers found in DNS. */
+         rc = LDAP_UNAVAILABLE;
+         goto out;
     }
 
     rc = LDAP_SUCCESS;
@@ -308,8 +364,12 @@ add_size:;
     if (request != NULL) {
        LDAP_FREE(request);
     }
+    if (hostent_head != NULL) {
+       LDAP_FREE(hostent_head);
+    }
     if (rc != LDAP_SUCCESS && hostlist != NULL) {
        LDAP_FREE(hostlist);
+       
     }
     return rc;
 #else
-- 
1.7.6

1	vip-ire	1.1	Implement priority/weight for DNS SRV records
2
3			From RFC 2782:
4
5			A client MUST attempt to contact the target host with the
6			lowest-numbered priority it can reach.
7
8			This patch sorts the DNS SRV records by their priority, and
9			additionally gives records with a larger weight a higher probability
10			of appearing earlier. This way, the DNS SRV records are tried in the
11			order of their priority.
12
13			Author: James M Leddy <james.leddy@redhat.com>
14			Upstream ITS: #7027
15			Resolves: #733078
16
17			---
18			libraries/libldap/dnssrv.c \| 106 ++++++++++++++++++++++++++++++++++----------
19			1 files changed, 83 insertions(+), 23 deletions(-)
20
21			diff --git a/libraries/libldap/dnssrv.c b/libraries/libldap/dnssrv.c
22			index 16b1544..40f93b4 100644
23			--- a/libraries/libldap/dnssrv.c
24			+++ b/libraries/libldap/dnssrv.c
25			@@ -174,6 +174,46 @@ int ldap_domain2dn(
26			return LDAP_SUCCESS;
27			}
28
29			+#ifdef HAVE_RES_QUERY
30			+#define DNSBUFSIZ (64*1024)
31			+typedef struct srv_record {
32			+ u_short priority;
33			+ u_short weight;
34			+ u_short port;
35			+ char hostname[DNSBUFSIZ];
36			+} srv_record;
37			+
38			+
39			+static int srv_cmp(const void aa, const void bb){
40			+ srv_record a=(srv_record )aa;
41			+ srv_record b=(srv_record )bb;
42			+ u_long total;
43			+
44			+ if(a->priority < b->priority) {
45			+ return -1;
46			+ }
47			+ if(a->priority > b->priority) {
48			+ return 1;
49			+ }
50			+ if(a->priority == b->priority){
51			+ /* targets with same priority are in psudeo random order */
52			+ if (a->weight == 0 && b->weight == 0) {
53			+ if (rand() % 2) {
54			+ return -1;
55			+ } else {
56			+ return 1;
57			+ }
58			+ }
59			+ total = a->weight + b->weight;
60			+ if (rand() % total < a->weight) {
61			+ return -1;
62			+ } else {
63			+ return 1;
64			+ }
65			+ }
66			+}
67			+#endif /* HAVE_RES_QUERY */
68			+
69			/*
70			* Lookup and return LDAP servers for domain (using the DNS
71			* SRV record _ldap._tcp.domain).
72			@@ -183,15 +223,16 @@ int ldap_domain2hostlist(
73			char **list )
74			{
75			#ifdef HAVE_RES_QUERY
76			-#define DNSBUFSIZ (64*1024)
77			- char *request;
78			- char *hostlist = NULL;
79			+ char *request;
80			+ char *hostlist = NULL;
81			+ srv_record *hostent_head=NULL;
82			+ int i;
83			int rc, len, cur = 0;
84			unsigned char reply[DNSBUFSIZ];
85			+ int hostent_count=0;
86
87			assert( domain != NULL );
88			assert( list != NULL );
89			-
90			if( *domain == '\0' ) {
91			return LDAP_PARAM_ERROR;
92			}
93			@@ -223,8 +264,7 @@ int ldap_domain2hostlist(
94			unsigned char *p;
95			char host[DNSBUFSIZ];
96			int status;
97			- u_short port;
98			- /* int priority, weight; */
99			+ u_short port, priority, weight;
100
101			/* Parse out query */
102			p = reply;
103			@@ -263,40 +303,56 @@ int ldap_domain2hostlist(
104			size = (p[0] << 8) \| p[1];
105			p += 2;
106			if (type == T_SRV) {
107			- int buflen;
108			status = dn_expand(reply, reply + len, p + 6, host, sizeof(host));
109			if (status < 0) {
110			goto out;
111			}
112			- /* ignore priority and weight for now */
113			- /* priority = (p[0] << 8) \| p[1]; */
114			- /* weight = (p[2] << 8) \| p[3]; */
115			+
116			+ /* Get priority weight and port */
117			+ priority = (p[0] << 8) \| p[1];
118			+ weight = (p[2] << 8) \| p[3];
119			port = (p[4] << 8) \| p[5];
120
121			if ( port == 0 \|\| host[ 0 ] == '\0' ) {
122			goto add_size;
123			}
124
125			- buflen = strlen(host) + STRLENOF(":65355 ");
126			- hostlist = (char *) LDAP_REALLOC(hostlist, cur + buflen + 1);
127			- if (hostlist == NULL) {
128			- rc = LDAP_NO_MEMORY;
129			- goto out;
130			+ hostent_head = (srv_record ) LDAP_REALLOC(hostent_head, (hostent_count+1)(sizeof(srv_record)));
131			+ if(hostent_head==NULL){
132			+ rc=LDAP_NO_MEMORY;
133			+ goto out;
134			+
135			}
136			- if (cur > 0) {
137			- /* not first time around */
138			- hostlist[cur++] = ' ';
139			- }
140			- cur += sprintf(&hostlist[cur], "%s:%hu", host, port);
141			+ hostent_head[hostent_count].priority=priority;
142			+ hostent_head[hostent_count].weight=weight;
143			+ hostent_head[hostent_count].port=port;
144			+ strncpy(hostent_head[hostent_count].hostname, host,255);
145			+ hostent_count=hostent_count+1;
146			}
147			add_size:;
148			p += size;
149			}
150			}
151			+ qsort(hostent_head, hostent_count, sizeof(srv_record), srv_cmp);
152			+
153			+ for(i=0; i<hostent_count; i++){
154			+ int buflen;
155			+ buflen = strlen(hostent_head[i].hostname) + STRLENOF(":65355" );
156			+ hostlist = (char *) LDAP_REALLOC(hostlist, cur+buflen+1);
157			+ if (hostlist == NULL) {
158			+ rc = LDAP_NO_MEMORY;
159			+ goto out;
160			+ }
161			+ if(cur>0){
162			+ hostlist[cur++]=' ';
163			+ }
164			+ cur += sprintf(&hostlist[cur], "%s:%hd", hostent_head[i].hostname, hostent_head[i].port);
165			+ }
166			+
167			if (hostlist == NULL) {
168			- /* No LDAP servers found in DNS. */
169			- rc = LDAP_UNAVAILABLE;
170			- goto out;
171			+ /* No LDAP servers found in DNS. */
172			+ rc = LDAP_UNAVAILABLE;
173			+ goto out;
174			}
175
176			rc = LDAP_SUCCESS;
177			@@ -308,8 +364,12 @@ add_size:;
178			if (request != NULL) {
179			LDAP_FREE(request);
180			}
181			+ if (hostent_head != NULL) {
182			+ LDAP_FREE(hostent_head);
183			+ }
184			if (rc != LDAP_SUCCESS && hostlist != NULL) {
185			LDAP_FREE(hostlist);
186			+
187			}
188			return rc;
189			#else
190			--
191			1.7.6
192