Merge pull request #18329 from miri64/gcoap_dns/enh/dns-caching

gcoap_dns: Add DNS cache support

sys/net/application_layer/gcoap/dns.c

@@ -23,6 +23,7 @@
 #include "net/credman.h"
 #include "net/gcoap.h"
 #include "net/af.h"
+#include "net/dns/cache.h"
 #include "net/ipv4/addr.h"
 #include "net/ipv6/addr.h"
 #include "net/sock/dns.h"
@@ -52,6 +53,14 @@ typedef struct {
      * initialized.
      */
     coap_pkt_t *pkt;
+#if IS_USED(MODULE_DNS_CACHE) || defined(DOXYGEN)
+    /**
+     * @brief   The queried hostname
+     *
+     * Only required for DNS caching and thus only available with module @ref net_dns_cache
+     */
+    const char *domain_name;
+#endif
     void *dns_buf;          /**< The buffer for the DNS message exchange */
     void *addr_out;         /**< Pointer to the resulting address */
     /**
@@ -113,9 +122,14 @@ static ssize_t _send(const void *buf, size_t len, const sock_udp_ep_t *remote,
 
 int gcoap_dns_query(const char *domain_name, void *addr_out, int family)
 {
+    int res;
+
+    if ((res = dns_cache_query(domain_name, addr_out, family)) > 0) {
+        return res;
+    }
+
     static uint8_t coap_buf[CONFIG_GCOAP_DNS_PDU_BUF_SIZE];
     static uint8_t dns_buf[CONFIG_DNS_MSG_LEN];
-    int res;
     coap_pkt_t pdu;
     _req_ctx_t req_ctx = {
         .resp_wait = MUTEX_INIT,
@@ -598,6 +612,9 @@ static int _dns_query(const char *domain_name, _req_ctx_t *req_ctx)
         domain_name,
         req_ctx->family
     );
+#if IS_USED(MODULE_DNS_CACHE)
+    req_ctx->domain_name = domain_name;
+#endif
 #if IS_USED(MODULE_GCOAP_DTLS)
     req_ctx->req_tag = _req_tag++;
 #endif
@@ -611,6 +628,16 @@ static int _dns_query(const char *domain_name, _req_ctx_t *req_ctx)
     return res;
 }
 
+static const char *_domain_name_from_ctx(_req_ctx_t *context)
+{
+#if IS_USED(MODULE_DNS_CACHE)
+    return context->domain_name;
+#else
+    (void)context;
+    return NULL;
+#endif
+}
+
 static void _resp_handler(const gcoap_request_memo_t *memo, coap_pkt_t *pdu,
                           const sock_udp_ep_t *remote)
 {
@@ -710,14 +737,20 @@ static void _resp_handler(const gcoap_request_memo_t *memo, coap_pkt_t *pdu,
     }
     switch (coap_get_content_type(pdu)) {
         case COAP_FORMAT_DNS_MESSAGE:
-        case COAP_FORMAT_NONE:
+        case COAP_FORMAT_NONE: {
+            uint32_t ttl;
+
             context->res = dns_msg_parse_reply(data, data_len, family,
-                                               context->addr_out, NULL);
-            if ((ENABLE_DEBUG) && (context->res < 0)) {
+                                               context->addr_out, &ttl);
+            if (context->res > 0) {
+                dns_cache_add(_domain_name_from_ctx(context), context->addr_out, context->res, ttl);
+            }
+            else if (ENABLE_DEBUG && (context->res < 0)) {
                 DEBUG("gcoap_dns: Unable to parse DNS reply: %d\n",
                       context->res);
             }
             break;
+        }
         default:
             context->res = -ENOMSG;
             break;

tests/gcoap_dns/main.c

@@ -533,6 +533,19 @@ static int _resp(int argc, char **argv)
     return 0;
 }
 
+static int _has_dns_cache(int argc, char **argv)
+{
+    (void)argc;
+    (void)argv;
+    if (IS_USED(MODULE_DNS_CACHE)) {
+        puts("DNS cache exists");
+    }
+    else {
+        puts("DNS cache does not exist");
+    }
+    return 0;
+}
+
 static const coap_resource_t _resources[] = {
     { "/", COAP_FETCH, _mock_dns_server, NULL },
 };
@@ -553,6 +566,7 @@ static const shell_command_t _shell_commands[] = {
     { "proxy", "Sets proxy URI for DoC queries", _proxy},
     { "query", "Sends DoC query for a hostname", _query},
     { "resp", "Set static response for mock DoC server", _resp},
+    { "has_dns_cache", "Check if DNS cache is activated", _has_dns_cache},
     { NULL, NULL, NULL }
 };
 

tests/gcoap_dns/tests/01-run.py

@@ -18,6 +18,11 @@ from testrunner.unittest import PexpectTestCase
 class TestGCoAPDNS(PexpectTestCase):
     LOGFILE = sys.stdout
 
+    def has_dns_cache(self):
+        self.spawn.sendline("has_dns_cache")
+        res = self.spawn.expect(["DNS cache does not exist", "DNS cache exists"])
+        return bool(res)
+
     def test_embedded_unittests(self):
         self.spawn.sendline("unittests")
         check_unittests(self.spawn)
@@ -162,8 +167,14 @@ class TestGCoAPDNS(PexpectTestCase):
         self.spawn.expect_exact(
             "Hostname example.org resolves to 192.0.0.1 (IPv4)"
         )
-        self.spawn.sendline("query example.org inet6")
-        self.spawn.expect_exact("Bad message")
+        if self.has_dns_cache():
+            self.spawn.sendline("query example.org inet6")
+            self.spawn.expect_exact(
+                "Hostname example.org resolves to 2001:db8::1 (IPv6)"
+            )
+        else:
+            self.spawn.sendline("query example.org inet6")
+            self.spawn.expect_exact("Bad message")
 
     def _expect_od_dump_of(self, hexbytes):
         for i in range((len(hexbytes) // 32) + 1):