sresolv: caching SRES_RECORD_ERR in case a CNAME is returned, too

Tracing the CNAMEs when doing cache lookups.

darcs-hash:20090123171341-db55f-dff8ddee2ac53bfba9dbb4bd1279380b2c63cf35.gz

libsofia-sip-ua/sresolv/example.com

@@ -42,6 +42,11 @@ _sips._udp	SRV 3 100 5061 sip00
 		SRV 4 50 5051 sip02
 		SRV 5 10 5061 sip01
 
+cloop	CNAME	cloop0
+cloop0	CNAME	cloop1
+cloop1	CNAME	cloop2
+cloop2	CNAME	cloop0
+
 sip	CNAME	sip00
 
 subnet  A6	0 3ff0:0::

libsofia-sip-ua/sresolv/sres.c

@@ -495,7 +495,9 @@ static int sres_decode_msg(sres_resolver_t *res,
 
 static char const *sres_toplevel(char buf[], size_t bsize, char const *domain);
 
-static sres_record_t *sres_create_record(sres_resolver_t *, sres_message_t *m);
+static sres_record_t *sres_create_record(sres_resolver_t *,
+					 sres_message_t *m,
+					 int nth);
 
 static sres_record_t *sres_init_rr_soa(sres_cache_t *cache,
 				       sres_soa_record_t *,
@@ -3539,7 +3541,7 @@ sres_decode_msg(sres_resolver_t *res,
 
   total = errorcount + m->m_ancount + m->m_nscount + m->m_arcount;
 
-  answers = su_zalloc(chome, (total + 1) * sizeof answers[0]);
+  answers = su_zalloc(chome, (total + 2) * sizeof answers[0]);
   if (!answers)
     return -1;
 
@@ -3548,7 +3550,7 @@ sres_decode_msg(sres_resolver_t *res,
     if (i < errorcount)
       rr = error = sres_create_error_rr(res->res_cache, query, err);
     else
-      rr = sres_create_record(res, m);
+      rr = sres_create_record(res, m, i - errorcount);
 
     if (!rr) {
       SU_DEBUG_5(("sres_create_record: %s\n", m->m_error));
@@ -3565,12 +3567,31 @@ sres_decode_msg(sres_resolver_t *res,
   }
 
   if (i < total) {
+    SU_DEBUG_5(("sres_decode_msg: %s\n", "less records than promised"));
     for (i = 0; i < total; i++)
       sres_cache_free_record(res->res_cache, answers[i]);
     su_free(chome, answers);
     return -1;
   }
 
+  if (m->m_ancount > 0 && errorcount == 0 && query->q_type < sres_qtype_tsig) {
+    char b0[8], b1[8];
+    for (i = 0; i < m->m_ancount; i++) {
+      if (query->q_type == answers[i]->sr_type)
+	break;
+    }
+
+    if (i == m->m_ancount) {
+      /* The queried request was not found. CNAME? */
+      SU_DEBUG_5(("sres_decode_msg: sent query %s, got %s\n",
+		  sres_record_type(query->q_type, b0),
+		  sres_record_type(answers[0]->sr_type, b1)));
+      rr = sres_create_error_rr(res->res_cache, query, err = SRES_RECORD_ERR);
+      memmove(answers + 1, answers, (sizeof answers[0]) * total++);
+      answers[errorcount++] = rr;
+    }
+  }
+
   for (i = 0; i < total; i++) {
     rr = answers[i];
 
@@ -3591,7 +3612,7 @@ sres_decode_msg(sres_resolver_t *res,
 
 static
 sres_record_t *
-sres_create_record(sres_resolver_t *res, sres_message_t *m)
+sres_create_record(sres_resolver_t *res, sres_message_t *m, int nth)
 {
   sres_cache_t *cache = res->res_cache;
   sres_record_t *sr, sr0[1];
@@ -3614,7 +3635,11 @@ sres_create_record(sres_resolver_t *res, sres_message_t *m)
 
   name[len] = 0;
 
-  SU_DEBUG_9(("RR received %s %s %s %d rdlen=%d\n", name,
+  SU_DEBUG_9(("%s RR received %s %s %s %d rdlen=%d\n",
+	      nth < m->m_ancount ? "ANSWER" :
+	      nth < m->m_ancount + m->m_nscount ? "AUTHORITY" :
+	      "ADDITIONAL",
+	      name,
 	      sres_record_type(sr->sr_type, btype),
 	      sres_record_class(sr->sr_class, bclass),
 	      sr->sr_ttl, sr->sr_rdlen));

libsofia-sip-ua/sresolv/sres_cache.c

@@ -169,15 +169,98 @@ void sres_cache_unref(sres_cache_t *cache)
   su_home_unref(cache->cache_home);
 }
 
+struct frame {
+  struct frame *previous;
+  char const *domain;
+};
+
+/** Count or get matching records from cache */
+static int
+sres_cache_get0(sres_htable_t *htable,
+		sres_rr_hash_entry_t **iter,
+		uint16_t type,
+		char const *domain,
+		time_t now,
+		sres_record_t **cached,
+		int len,
+		struct frame *previous)
+{
+  sres_cname_record_t *cname = NULL;
+  int dcount = 0, derrorcount = 0, ccount = 0;
+
+  for (; iter && *iter; iter = sres_htable_next(htable, iter)) {
+    sres_record_t *rr = (*iter)->rr;
+
+    if (rr == NULL)
+      continue;
+    if (now > (*iter)->rr_expires)
+      continue;
+    if (rr->sr_name == NULL)
+      continue;
+    if (!su_casematch(rr->sr_name, domain))
+      continue;
+
+    if (rr->sr_type == type || type == sres_qtype_any) {
+      if (rr->sr_status == SRES_RECORD_ERR && type == sres_qtype_any)
+	continue;
+      if (cached) {
+	if (dcount >= len)
+	  return -1;
+	cached[dcount] = rr, rr->sr_refcount++;
+      }
+      dcount++;
+      if (rr->sr_status)
+	derrorcount++;
+    }
+
+    if (type != sres_type_cname && rr->sr_type == sres_type_cname) {
+      if (rr->sr_status == 0)
+	cname = rr->sr_cname;
+    }
+  }
+
+  if (cname && dcount == derrorcount) {
+    /* Nothing found, trace CNAMEs */
+    struct frame *f, frame = { previous, domain };
+    unsigned hash = sres_hash_key(domain = cname->cn_cname);
+
+    if (cached) {
+      if (dcount >= len)
+	return -1;
+      cached[dcount] = (sres_record_t *)cname;
+      cname->cn_record->r_refcount++;
+    }
+    dcount++;
+
+    /* Check for cname loops */
+    for (f = previous; f; f = f->previous) {
+      if (su_casematch(domain, f->domain))
+	break;
+    }
+
+    if (f == NULL) {
+      ccount = sres_cache_get0(htable, sres_htable_hash(htable, hash),
+			       type, domain, now,
+			       cached ? cached + dcount : NULL,
+			       cached ? len - dcount : 0,
+			       &frame);
+    }
+    if (ccount < 0)
+      return ccount;
+  }
+
+  return dcount + ccount;
+}
+
 /** Get a list of matching records from cache. */
 int sres_cache_get(sres_cache_t *cache,
 		   uint16_t type,
 		   char const *domain,
 		   sres_record_t ***return_cached)
 {
-  sres_record_t **result = NULL, *rr = NULL;
-  sres_rr_hash_entry_t **rr_iter, **rr_iter2;
-  int result_size, rr_count = 0;
+  sres_record_t **result = NULL;
+  sres_rr_hash_entry_t **slot;
+  int result_size, i, j;
   unsigned hash;
   time_t now;
   char b[8];
@@ -198,28 +281,16 @@ int sres_cache_get(sres_cache_t *cache,
   time(&now);
 
   /* First pass: just count the number of rr:s for array allocation */
-  rr_iter2 = sres_htable_hash(cache->cache_hash, hash);
-
-  /* Find the domain records from the hash table */
-  for (rr_iter = rr_iter2;
-       rr_iter && *rr_iter;
-       rr_iter = sres_htable_next(cache->cache_hash, rr_iter)) {
-    rr = (*rr_iter)->rr;
-
-    if (rr != NULL &&
-	now <= (*rr_iter)->rr_expires &&
-        (type == sres_qtype_any || rr->sr_type == type) &&
-        rr->sr_name != NULL &&
-        su_casematch(rr->sr_name, domain))
-      rr_count++;
-  }
+  slot = sres_htable_hash(cache->cache_hash, hash);
 
-  if (rr_count == 0) {
+  i = sres_cache_get0(cache->cache_hash, slot, type, domain, now,
+		      NULL, 0, NULL);
+  if (i <= 0) {
     UNLOCK(cache);
     return 0;
   }
 
-  result_size = (sizeof *result) * (rr_count + 1);
+  result_size = (sizeof *result) * (i + 1);
   result = su_zalloc(cache->cache_home, result_size);
   if (result == NULL) {
     UNLOCK(cache);
@@ -227,35 +298,30 @@ int sres_cache_get(sres_cache_t *cache,
   }
 
   /* Second pass: add the rr pointers to the allocated array */
-
-  for (rr_iter = rr_iter2, rr_count = 0;
-       rr_iter && *rr_iter;
-       rr_iter = sres_htable_next(cache->cache_hash, rr_iter)) {
-    rr = (*rr_iter)->rr;
-
-    if (rr != NULL &&
-	now <= (*rr_iter)->rr_expires &&
-        (type == sres_qtype_any || rr->sr_type == type) &&
-        rr->sr_name != NULL &&
-        su_casematch(rr->sr_name, domain)) {
-      SU_DEBUG_9(("rr found in cache: %s %02d\n",
-		  rr->sr_name, rr->sr_type));
-
-      result[rr_count++] = rr;
-      rr->sr_refcount++;
+  j = sres_cache_get0(cache->cache_hash, slot, type, domain, now,
+		      result, i, NULL);
+  if (i != j) {
+    /* Uh-oh. */
+    SU_DEBUG_9(("%s(%p, %s, \"%s\") got %d != %d\n", "sres_cache_get",
+		(void *)cache, sres_record_type(type, b), domain, i, j));
+    for (i = 0; i < result_size; i++) {
+      if (result[i])
+	result[i]->sr_refcount--;
     }
+    su_free(cache->cache_home, result);
+    return 0;
   }
 
-  result[rr_count] = NULL;
+  result[i] = NULL;
 
   UNLOCK(cache);
 
   SU_DEBUG_9(("%s(%p, %s, \"%s\") returned %d entries\n", "sres_cache_get",
-	      (void *)cache, sres_record_type(type, b), domain, rr_count));
+	      (void *)cache, sres_record_type(type, b), domain, i));
 
   *return_cached = result;
 
-  return rr_count;
+  return i;
 }
 
 sres_record_t *

libsofia-sip-ua/sresolv/test_sresolv.c

@@ -90,6 +90,10 @@ typedef unsigned _int32 uint32_t;
 #include <signal.h>
 #endif
 
+#include <sofia-sip/su_log.h>
+
+extern su_log_t sresolv_log[];
+
 char const name[] = "test_sresolv";
 
 struct sres_context_s
@@ -982,24 +986,133 @@ int test_srv(sres_context_t *ctx)
 int test_cname(sres_context_t *ctx)
 {
   sres_resolver_t *res = ctx->resolver;
-  sres_record_t **result;
-  const sres_cname_record_t *rr;
+  sres_record_t **result, *sr;
+  const sres_cname_record_t *cn;
   char const *domain = "sip.example.com";
 
   BEGIN();
 
+  TEST_1(sres_query(res, test_answer, ctx, sres_type_naptr, domain));
+  TEST_RUN(ctx);
+
+  TEST_1(result = ctx->result);
+  TEST_1(sr = result[0]);
+  TEST_1(sr->sr_record->r_status == SRES_RECORD_ERR);
+  TEST_1(cn = result[1]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "sip00.example.com.");
+
+  sres_free_answers(res, ctx->result), ctx->result = NULL;
+
+  TEST_1(result = sres_cached_answers(res, sres_type_naptr, domain));
+  TEST_1(sr = result[0]);
+  TEST_1(sr->sr_record->r_status == SRES_RECORD_ERR);
+  TEST_1(cn = result[1]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "sip00.example.com.");
+
+  sres_free_answers(res, result), ctx->result = NULL;
+
+  TEST_1(result = sres_cached_answers(res, sres_qtype_any, domain));
+  TEST_1(cn = result[0]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "sip00.example.com.");
+  /* We might have A record, or then not */
+
+  sres_free_answers(res, result), ctx->result = NULL;
+
+  TEST_1(sres_query(res, test_answer, ctx, sres_type_a, domain));
+  TEST_RUN(ctx);
+
+  TEST_1(result = ctx->result);
+  TEST_1(cn = result[0]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "sip00.example.com.");
+  TEST_1(sr = result[1]);
+  TEST(sr->sr_record->r_class, sres_class_in);
+  TEST(sr->sr_record->r_type, sres_type_a);
+
+  sres_free_answers(res, ctx->result), ctx->result = NULL;
+
+  TEST_1(result = sres_cached_answers(res, sres_type_a, domain));
+  TEST_1(cn = result[0]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "sip00.example.com.");
+  TEST_1(sr = result[1]);
+  TEST(sr->sr_record->r_class, sres_class_in);
+  TEST(sr->sr_record->r_type, sres_type_a);
+
+  sres_free_answers(res, result);
+
+  domain = "cloop.example.com";
+
   TEST_1(sres_query(res, test_answer, ctx, sres_type_a, domain));
   TEST_RUN(ctx);
 
   TEST_1(result = ctx->result);
-  TEST_1(rr = result[0]->sr_cname);
-  TEST(rr->cn_record->r_class, sres_class_in);
-  TEST(rr->cn_record->r_type, sres_type_cname);
-  TEST(rr->cn_record->r_ttl, 60);
-  TEST_S(rr->cn_cname, "sip00.example.com.");
+  TEST_1(sr = result[0]);
+  TEST_1(sr->sr_record->r_status == SRES_RECORD_ERR);
+  TEST_1(cn = result[1]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop0.example.com.");
+  TEST_1(cn = result[2]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop1.example.com.");
+  TEST_1(cn = result[3]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop2.example.com.");
+  TEST_1(cn = result[4]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop0.example.com.");
+  TEST_1(result[5] == NULL);
 
   sres_free_answers(res, ctx->result), ctx->result = NULL;
 
+  TEST_1(result = sres_cached_answers(res, sres_type_a, domain));
+  TEST_1(sr = result[0]);
+  TEST_1(sr->sr_record->r_status == SRES_RECORD_ERR);
+  TEST_1(cn = result[1]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop0.example.com.");
+  TEST_1(cn = result[2]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop1.example.com.");
+  TEST_1(cn = result[3]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop2.example.com.");
+  TEST_1(cn = result[4]->sr_cname);
+  TEST(cn->cn_record->r_class, sres_class_in);
+  TEST(cn->cn_record->r_type, sres_type_cname);
+  TEST(cn->cn_record->r_ttl, 60);
+  TEST_S(cn->cn_cname, "cloop0.example.com.");
+  TEST_1(result[5] == NULL);
+
+  sres_free_answers(res, result);
+
   END();
 }
 
@@ -1892,10 +2005,6 @@ void usage(int exitcode)
   exit(exitcode);
 }
 
-#include <sofia-sip/su_log.h>
-
-extern su_log_t sresolv_log[];
-
 int main(int argc, char **argv)
 {
   int i;