feat: expose dns discovery thru c-bindings

examples/c-bindings/main.c

@@ -86,6 +86,14 @@ int main(int argc, char *argv[])
   if (isError(response))
     return 1;
 
+
+  /*
+  // To use dns discovery, and retrieve nodes from a enrtree url
+  response = waku_dns_discovery("enrtree://AOGECG2SPND25EEFMAJ5WF3KSGJNSGV356DSTL2YVLLZWIV6SAYBM@test.waku.nodes.status.im", "", 0); // Discover Nodes
+  if (isError(response))
+    return 1;
+  printf("Discovered nodes: %s\n", response);
+  */
   
   /*
   // To see a store query in action:

library/README.md

@@ -1018,6 +1018,38 @@ An `error` message otherwise.
 }
 ```
 
+## DNS Discovery
+
+### `extern char* waku_dns_discovery(char* url, char* nameserver, int timeoutMs)`
+Returns a list of multiaddress given a url to a DNS discoverable ENR tree
+
+**Parameters**
+
+1. `char* url`: URL containing a discoverable ENR tree
+2. `char* nameserver`: The nameserver to resolve the ENR tree url. 
+   If `NULL` or empty, it will automatically use the default system dns.
+3. `int timeoutMs`: Timeout value in milliseconds to execute the call.
+   If the function execution takes longer than this value,
+   the execution will be canceled and an error returned.
+   Use `0` for no timeout.
+
+**Returns**
+
+A [`JsonResponse`](#jsonresponse-type).
+If the execution is successful, the `result` field contains an array with multiaddresses.
+An `error` message otherwise.
+
+```json
+{
+  "result": [
+    "/ip4/134.209.139.210/tcp/30303/p2p/16Uiu2HAmPLe7Mzm8TsYUubgCAW1aJoeFScxrLj8ppHFivPo97bUZ",
+    "/ip4/104.154.239.128/tcp/30303/p2p/16Uiu2HAmJb2e28qLXxT5kZxVUUoJt72EMzNGXB47Rxx5hw3q4YjS",
+    "/ip4/47.242.210.73/tcp/30303/p2p/16Uiu2HAkvWiyFsgRhuJEb9JfjYxEkoHLgnUQmr1N5mKWnYjxYRVm"
+  ]
+}
+```
+
+
 ## Utils
 
 ### `extern char* waku_utils_base64_encode(char* data)`

library/api_discovery.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"C"
+
+	mobile "github.com/status-im/go-waku/mobile"
+)
+
+// RetrieveNodes returns a list of multiaddress given a url to a DNS discoverable ENR tree
+// The nameserver can optionally be specified to resolve the enrtree url. Otherwise NULL or
+// empty to automatically use the default system dns.
+// If ms is greater than 0, the subscription must happen before the timeout
+// (in milliseconds) is reached, or an error will be returned
+//
+//export waku_dns_discovery
+func waku_dns_discovery(url *C.char, nameserver *C.char, ms C.int) *C.char {
+	response := mobile.DnsDiscovery(C.GoString(url), C.GoString(nameserver), int(ms))
+	return C.CString(response)
+}

mobile/api_discovery.go

@@ -0,0 +1,39 @@
+package gowaku
+
+import (
+	"context"
+	"time"
+
+	"github.com/status-im/go-waku/waku/v2/dnsdisc"
+)
+
+func DnsDiscovery(url string, nameserver string, ms int) string {
+	var ctx context.Context
+	var cancel context.CancelFunc
+
+	if ms > 0 {
+		ctx, cancel = context.WithTimeout(context.Background(), time.Duration(int(ms))*time.Millisecond)
+		defer cancel()
+	} else {
+		ctx = context.Background()
+	}
+
+	var dnsDiscOpt []dnsdisc.DnsDiscoveryOption
+	if nameserver != "" {
+		dnsDiscOpt = append(dnsDiscOpt, dnsdisc.WithNameserver(nameserver))
+	}
+
+	nodes, err := dnsdisc.RetrieveNodes(ctx, url, dnsDiscOpt...)
+	if err != nil {
+		return MakeJSONResponse(err)
+	}
+
+	var ma []string
+	for _, n := range nodes {
+		for _, addr := range n.Addresses {
+			ma = append(ma, addr.String())
+		}
+	}
+
+	return PrepareJSONResponse(ma, nil)
+}