X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Ftypes.c;h=14afc900b3fff77cb646b6056d2477c7afad90ee;hb=2bd4b9f4167fa254b424385ee430d1402ef087b7;hp=cfe785075ed92b9cf3be56a562808a8ca3873ca6;hpb=a889f4bef2235d4358c39113a745551773f2450b;p=adns.git

diff --git a/src/types.c b/src/types.c
index cfe7850..14afc90 100644
--- a/src/types.c
+++ b/src/types.c
@@ -63,7 +63,7 @@
  * _mailbox                   (pap +pap_mailbox822)
  * _rp                        (pa)
  * _soa                       (pa,mf,cs)
- * _srv*                      (qdpl,(pap),pa,mf,di,(csp),cs)
+ * _srv*                      (qdpl,(pap),pa,mf,di,(csp),cs,postsort)
  * _flat                      (mf)
  *
  * within each section:
@@ -76,6 +76,7 @@
  *    mf_*
  *    csp_*
  *    cs_*
+ *    postsort_*
  */
 
 /*
@@ -1003,7 +1004,7 @@ static adns_status cs_soa(vbuf *vb, const void *datap) {
 }
 
 /*
- * _srv*  (pa*2,di,cs*2,qdpl)
+ * _srv*  (pa*2,di,cs*2,qdpl,postsort)
  */
 
 static adns_status qdpl_srv(adns_state ads,
@@ -1036,8 +1037,8 @@ static adns_status qdpl_srv(adns_state ads,
 }
 
 static adns_status pap_srv_begin(const parseinfo *pai, int *cbyte_io, int max,
-				 adns_rr_srvraw *rrp
-				   /* might be adns_rr_srvha* */) {
+				 adns_rr_srvha *rrp
+				   /* might be adns_rr_srvraw* */) {
   const byte *dgram= pai->dgram;
   int ti, cbyte;
 
@@ -1096,8 +1097,8 @@ static int di_srv(adns_state ads, const void *datap_a, const void *datap_b) {
   return 0;
 }
 
-static adns_status csp_srv_begin(vbuf *vb, const adns_rr_srvraw *rrp
-				   /* might be adns_rr_srvha* */) {
+static adns_status csp_srv_begin(vbuf *vb, const adns_rr_srvha *rrp
+				   /* might be adns_rr_srvraw* */) {
   char buf[30];
   sprintf(buf,"%u %u %u ", rrp->priority, rrp->weight, rrp->port);
   CSP_ADDSTR(buf);
@@ -1108,7 +1109,7 @@ static adns_status cs_srvraw(vbuf *vb, const void *datap) {
   const adns_rr_srvraw *rrp= datap;
   adns_status st;
   
-  st= csp_srv_begin(vb,rrp);  if (st) return st;
+  st= csp_srv_begin(vb,(const void*)rrp);  if (st) return st;
   return csp_domain(vb,rrp->host);
 }
 
@@ -1116,10 +1117,71 @@ static adns_status cs_srvha(vbuf *vb, const void *datap) {
   const adns_rr_srvha *rrp= datap;
   adns_status st;
 
-  st= csp_srv_begin(vb,datap);  if (st) return st;
+  st= csp_srv_begin(vb,(const void*)datap);  if (st) return st;
   return csp_hostaddr(vb,&rrp->ha);
 }
 
+static void postsort_srv(adns_state ads, void *array, int nrrs,
+			 const struct typeinfo *typei) {
+  /* we treat everything in the array as if it were an adns_rr_srvha
+   * even though the array might be of adns_rr_srvraw.  That's OK
+   * because they have the same prefix, which is all we access.
+   * We use typei->rrsz, too, rather than naive array indexing, of course.
+   */
+  char *workbegin, *workend, *search, *arrayend;
+  const adns_rr_srvha *rr;
+  union { adns_rr_srvha ha; adns_rr_srvraw raw; } rrtmp;
+  int cpriority, totalweight, runtotal;
+  long randval;
+
+  for (workbegin= array, arrayend= workbegin + typei->rrsz * nrrs;
+       workbegin < arrayend;
+       workbegin= workend) {
+    cpriority= (rr=(void*)workbegin)->priority;
+    
+    for (workend= workbegin, totalweight= 0;
+	 workend < arrayend && (rr=(void*)workend)->priority == cpriority;
+	 workend += typei->rrsz) {
+      totalweight += rr->weight;
+    }
+
+    /* Now workbegin..(workend-1) incl. are exactly all of the RRs of
+     * cpriority.  From now on, workbegin points to the `remaining'
+     * records: we select one record at a time (RFC2782 `Usage rules'
+     * and `Format of the SRV RR' subsection `Weight') to place at
+     * workbegin (swapping with the one that was there, and then
+     * advance workbegin. */
+    for (;
+	 workbegin + typei->rrsz < workend; /* don't bother if just one */
+	 workbegin += typei->rrsz) {
+      
+      randval= nrand48(ads->rand48xsubi);
+      randval %= (totalweight + 1);
+        /* makes it into 0..totalweight inclusive; with 2^10 RRs,
+	 * totalweight must be <= 2^26 so probability nonuniformity is
+	 * no worse than 1 in 2^(31-26) ie 1 in 2^5, ie
+	 *  abs(log(P_intended(RR_i) / P_actual(RR_i)) <= log(2^-5).
+	 */
+
+      for (search=workbegin, runtotal=0;
+	   (runtotal += (rr=(void*)search)->weight) < randval;
+	   search += typei->rrsz);
+      assert(search < arrayend);
+      totalweight -= rr->weight;
+      if (search != workbegin) {
+	memcpy(&rrtmp, workbegin, typei->rrsz);
+	memcpy(workbegin, search, typei->rrsz);
+	memcpy(search, &rrtmp, typei->rrsz);
+      }
+    }
+  }
+  /* tests:
+   *  dig -t srv _srv._tcp.test.iwj.relativity.greenend.org.uk.
+   *   ./adnshost_s -t srv- _sip._udp.voip.net.cam.ac.uk.
+   *   ./adnshost_s -t srv- _jabber._tcp.jabber.org
+   */
+}
+
 /*
  * _flat   (mf)
  */
@@ -1137,13 +1199,13 @@ static void mf_flat(adns_query qu, void *data) { }
 
 #define DEEP_TYPE(code,rrt,fmt,memb,parser,comparer,printer)	\
  { adns_r_##code, rrt,fmt,TYPESZ_M(memb), mf_##memb,		\
-      printer,parser,comparer, adns__qdpl_normal }
+      printer,parser,comparer, adns__qdpl_normal,0 }
 #define FLAT_TYPE(code,rrt,fmt,memb,parser,comparer,printer)	\
  { adns_r_##code, rrt,fmt,TYPESZ_M(memb), mf_flat,		\
-     printer,parser,comparer, adns__qdpl_normal }
-#define XTRA_TYPE(code,rrt,fmt,memb,parser,comparer,printer,qdpl)	\
- { adns_r_##code, rrt,fmt,TYPESZ_M(memb), mf_##memb,			\
-    printer,parser,comparer,qdpl }
+     printer,parser,comparer, adns__qdpl_normal,0 }
+#define XTRA_TYPE(code,rrt,fmt,memb,parser,comparer,printer,qdpl,postsort) \
+ { adns_r_##code, rrt,fmt,TYPESZ_M(memb), mf_##memb,			   \
+    printer,parser,comparer,qdpl,postsort }
 
 static const typeinfo typeinfos[] = {
 /* Must be in ascending order of rrtype ! */
@@ -1158,13 +1220,15 @@ DEEP_TYPE(hinfo,  "HINFO", 0, intstrpair,pa_hinfo,   0,        cs_hinfo      ),
 DEEP_TYPE(mx_raw, "MX",   "raw",intstr,  pa_mx_raw,  di_mx_raw,cs_inthost    ),
 DEEP_TYPE(txt,    "TXT",   0,   manyistr,pa_txt,     0,        cs_txt        ),
 DEEP_TYPE(rp_raw, "RP",   "raw",strpair, pa_rp,      0,        cs_rp         ),
-XTRA_TYPE(srv_raw,"SRV",  "raw",srvraw , pa_srvraw, di_srv,cs_srvraw,qdpl_srv),
+XTRA_TYPE(srv_raw,"SRV",  "raw",srvraw , pa_srvraw,  di_srv,   cs_srvraw,
+	                                               qdpl_srv, postsort_srv),
 
 FLAT_TYPE(addr,   "A",  "addr", addr,    pa_addr,    di_addr,  cs_addr       ),
 DEEP_TYPE(ns,     "NS", "+addr",hostaddr,pa_hostaddr,di_hostaddr,cs_hostaddr ),
 DEEP_TYPE(ptr,    "PTR","checked",str,   pa_ptr,     0,        cs_domain     ),
 DEEP_TYPE(mx,     "MX", "+addr",inthostaddr,pa_mx,   di_mx,    cs_inthostaddr),
-XTRA_TYPE(srv,    "SRV","+addr",srvha,   pa_srvha,  di_srv,cs_srvha, qdpl_srv),
+XTRA_TYPE(srv,    "SRV","+addr",srvha,   pa_srvha,   di_srv,   cs_srvha,
+          	                                       qdpl_srv, postsort_srv),
 
 DEEP_TYPE(soa,    "SOA","822",  soa,     pa_soa,     0,        cs_soa        ),
 DEEP_TYPE(rp,     "RP", "822",  strpair, pa_rp,      0,        cs_rp         ),