Added new API calls for serializing/restoring the DNS cache

-  bool ndpi_address_cache_dump(struct ndpi_address_cache *cache, char *path, u_int32_t epoch_now);
-  u_int32_t ndpi_address_cache_restore(struct ndpi_address_cache *cache, char *path, u_int32_t epoch_now);

example/ndpiReader.c

@@ -6419,12 +6419,13 @@ void domainCacheTestUnit() {
   ndpi_ip_addr_t ip;
   u_int32_t epoch_now = (u_int32_t)time(NULL);
   struct ndpi_address_cache_item *ret;
-
+  const char *fname = "/tmp/cache.dump";
+
   assert(cache);
 
   memset(&ip, 0, sizeof(ip));
   ip.ipv4 = 12345678;
-  assert(ndpi_address_cache_insert(cache, ip, "nodomain.local", epoch_now, 0) == true);
+  assert(ndpi_address_cache_insert(cache, ip, "nodomain.local", epoch_now, 32) == true);
 
   ip.ipv4 = 87654321;
   assert(ndpi_address_cache_insert(cache, ip, "hello.local", epoch_now, 0) == true);
@@ -6434,7 +6435,19 @@ void domainCacheTestUnit() {
   sleep(1);
   assert(ndpi_address_cache_find(cache, ip, time(NULL)) == NULL);
 
+  assert(ndpi_address_cache_dump(cache, (char*)fname, epoch_now));
+  ndpi_term_address_cache(cache);
+
+  cache = ndpi_init_address_cache(32000);
+  assert(cache);
+  assert(ndpi_address_cache_restore(cache, (char*)fname, epoch_now) == 1);
+
+  ip.ipv4 = 12345678;
+  assert((ret = ndpi_address_cache_find(cache, ip, epoch_now)) != NULL);
+  assert(strcmp(ret->hostname, "nodomain.local") == 0);
+
   ndpi_term_address_cache(cache);
+  unlink(fname);
 }
 
 /* *********************************************** */

src/include/ndpi_api.h

@@ -2344,6 +2344,8 @@ extern "C" {
 
   struct ndpi_address_cache_item* ndpi_cache_address_find(struct ndpi_detection_module_struct *ndpi_struct,
 							  ndpi_ip_addr_t ip_addr);
+  bool ndpi_address_cache_dump(struct ndpi_address_cache *cache, char *path, u_int32_t epoch_now);
+  u_int32_t ndpi_address_cache_restore(struct ndpi_address_cache *cache, char *path, u_int32_t epoch_now);
 
   /* ******************************* */
 

src/lib/ndpi_cache.c

@@ -396,6 +396,73 @@ bool ndpi_address_cache_insert(struct ndpi_address_cache *cache,
   return(true);
 }
 
+/* ***************************************************** */
+
+bool ndpi_address_cache_dump(struct ndpi_address_cache *cache,
+			     char *path, u_int32_t epoch_now) {
+  FILE *fd = fopen(path, "w");
+  u_int i;
+
+  if(!fd) return(false);
+
+  for(i=0; i<cache->num_root_nodes; i++) {
+    struct ndpi_address_cache_item *root = cache->address_cache_root[i];
+
+    while(root != NULL) {
+      char buf[33];
+      u_char *a = (u_char*)&(root->addr);
+      u_int j, idx;
+
+      if(epoch_now && (root->expire_epoch < epoch_now))
+	continue; /* Expired epoch */
+
+      for(j=0, idx=0; j<sizeof(ndpi_ip_addr_t); j++, idx += 2)
+	snprintf(&buf[idx], sizeof(buf)-idx, "%02X", a[j]);	 
+
+      fprintf(fd, "%s\t%s\t%u\n", buf, root->hostname, root->expire_epoch);
+
+      root = root->next;
+    }
+  }
+
+  fclose(fd);
+  return(true);
+}
+
+/* ***************************************************** */
+
+/* Return the number of items restored */
+u_int32_t ndpi_address_cache_restore(struct ndpi_address_cache *cache, char *path, u_int32_t epoch_now) {
+  FILE *fd = fopen(path,  "r");
+  char ip[33], hostname[256];
+  u_int32_t epoch, num_added = 0;
+
+  if(!fd) return(false);
+
+  while(fscanf(fd, "%s\t%s\t%u\n", ip, hostname, &epoch) > 0) {    
+    if(epoch >= epoch_now) { /* Entry not yet expired */
+      u_int ttl = epoch-epoch_now;
+      ndpi_ip_addr_t addr;
+      char *a = (char*)&addr;
+      u_int i, j;
+
+      for(i=0, j=0; i<(sizeof(ndpi_ip_addr_t)*2); i += 2, j++) {
+	char buf[3];
+
+	buf[0] = ip[i], buf[1] = ip[i+1], buf[2] = '\0';
+	a[j] = strtol(buf, NULL, 16);
+      }
+
+      if(ndpi_address_cache_insert(cache, addr, hostname, epoch_now, ttl))
+	num_added++;
+    }
+  }
+
+  fclose(fd);
+
+  return(num_added);
+}
+
 /* ***************************************************** */
 /* ***************************************************** */