diff --git a/library/c/api.go b/library/c/api.go
index 81ba8f57a..ccb025579 100644
--- a/library/c/api.go
+++ b/library/c/api.go
@@ -10,15 +10,15 @@ package main
 #define RET_ERR               1
 #define RET_MISSING_CALLBACK  2
 
-typedef void (*WakuCallBack) (const char* msg, size_t len_0);
+typedef void (*WakuCallBack) (const char* msg, void * user_data);
 */
 import "C"
 import (
+	"errors"
 	"fmt"
 	"unsafe"
 
 	"github.com/waku-org/go-waku/library"
-	"github.com/waku-org/go-waku/waku/v2/protocol"
 )
 
 const retOk = C.RET_OK
@@ -92,25 +92,25 @@ func main() {}
 // - dns4DomainName: the domain name resolving to the node's public IPv4 address.
 //
 //export waku_new
-func waku_new(configJSON *C.char, onErrCb C.WakuCallBack) C.int {
+func waku_new(configJSON *C.char, onErr C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.NewNode(C.GoString(configJSON))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErr, userData)
 }
 
 // Starts the waku node
 //
 //export waku_start
-func waku_start(onErrCb C.WakuCallBack) C.int {
+func waku_start(onErr C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.Start()
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErr, userData)
 }
 
 // Stops a waku node
 //
 //export waku_stop
-func waku_stop(onErrCb C.WakuCallBack) C.int {
+func waku_stop(onErr C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.Stop()
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErr, userData)
 }
 
 // Determine is a node is started or not
@@ -126,96 +126,97 @@ func waku_is_started() C.int {
 
 type fn func() (string, error)
 
-func singleFnExec(f fn, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func singleFnExec(f fn, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	result, err := f()
 	if err != nil {
-		return execErrCB(onErrCb, err)
+		return execErrCB(err, cb, userData)
 	}
-	return execOkCB(onOkCb, result)
+	return execOkCB(result, cb, userData)
 }
 
 // Obtain the peer ID of the waku node
 //
 //export waku_peerid
-func waku_peerid(onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_peerid(cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.PeerID()
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Obtain the multiaddresses the wakunode is listening to
 //
 //export waku_listen_addresses
-func waku_listen_addresses(onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_listen_addresses(cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.ListenAddresses()
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Add node multiaddress and protocol to the wakunode peerstore
 //
 //export waku_add_peer
-func waku_add_peer(address *C.char, protocolID *C.char, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_add_peer(address *C.char, protocolID *C.char, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.AddPeer(C.GoString(address), C.GoString(protocolID))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Connect to peer at multiaddress. if ms > 0, cancel the function execution if it takes longer than N milliseconds
 //
 //export waku_connect
-func waku_connect(address *C.char, ms C.int, onErrCb C.WakuCallBack) C.int {
+func waku_connect(address *C.char, ms C.int, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.Connect(C.GoString(address), int(ms))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
 
 // Connect to known peer by peerID. if ms > 0, cancel the function execution if it takes longer than N milliseconds
 //
 //export waku_connect_peerid
-func waku_connect_peerid(peerID *C.char, ms C.int, onErrCb C.WakuCallBack) C.int {
+func waku_connect_peerid(peerID *C.char, ms C.int, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.ConnectPeerID(C.GoString(peerID), int(ms))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
 
 // Close connection to a known peer by peerID
 //
 //export waku_disconnect
-func waku_disconnect(peerID *C.char, onErrCb C.WakuCallBack) C.int {
+func waku_disconnect(peerID *C.char, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.Disconnect(C.GoString(peerID))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
 
 // Get number of connected peers
 //
 //export waku_peer_cnt
-func waku_peer_cnt(onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_peer_cnt(cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		peerCnt, err := library.PeerCnt()
 		return fmt.Sprintf("%d", peerCnt), err
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Create a content topic string according to RFC 23
 //
 //export waku_content_topic
-func waku_content_topic(applicationName *C.char, applicationVersion C.uint, contentTopicName *C.char, encoding *C.char, onOkCb C.WakuCallBack) C.int {
-	contentTopic, _ := protocol.NewContentTopic(C.GoString(applicationName), uint32(applicationVersion), C.GoString(contentTopicName), C.GoString(encoding))
-	return execOkCB(onOkCb, contentTopic.String())
+func waku_content_topic(applicationName *C.char, applicationVersion C.uint, contentTopicName *C.char, encoding *C.char, onOkCb C.WakuCallBack, userData unsafe.Pointer) C.int {
+	//contentTopic, _ := protocol.NewContentTopic(C.GoString(applicationName), uint32(applicationVersion), C.GoString(contentTopicName), C.GoString(encoding))
+	return execErrCB(errors.New("OOPS"), onOkCb, userData)
+	// return execOkCB(contentTopic.String(), onOkCb, userData)
 }
 
 // Create a pubsub topic string according to RFC 23
 //
 //export waku_pubsub_topic
-func waku_pubsub_topic(name *C.char, encoding *C.char, onOkCb C.WakuCallBack) C.int {
+func waku_pubsub_topic(name *C.char, encoding *C.char, onOkCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	topic := library.PubsubTopic(C.GoString(name), C.GoString(encoding))
-	return execOkCB(onOkCb, topic)
+	return execOkCB(topic, onOkCb, userData)
 }
 
 // Get the default pubsub topic used in waku2: /waku/2/default-waku/proto
 //
 //export waku_default_pubsub_topic
-func waku_default_pubsub_topic(onOkCb C.WakuCallBack) C.int {
-	return execOkCB(onOkCb, library.DefaultPubsubTopic())
+func waku_default_pubsub_topic(onOkCb C.WakuCallBack, userData unsafe.Pointer) C.int {
+	return execOkCB(library.DefaultPubsubTopic(), onOkCb, userData)
 }
 
 // Register callback to act as signal handler and receive application signals
@@ -230,8 +231,8 @@ func waku_set_event_callback(cb C.WakuCallBack) {
 // Retrieve the list of peers known by the waku node
 //
 //export waku_peers
-func waku_peers(onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_peers(cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.Peers()
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
diff --git a/library/c/api_discovery.go b/library/c/api_discovery.go
index 31171e980..53031c257 100644
--- a/library/c/api_discovery.go
+++ b/library/c/api_discovery.go
@@ -5,7 +5,11 @@ package main
 */
 import "C"
 
-import "github.com/waku-org/go-waku/library"
+import (
+	"unsafe"
+
+	"github.com/waku-org/go-waku/library"
+)
 
 // Returns a list of objects containing the peerID, enr and multiaddresses for each node found
 //
@@ -17,17 +21,17 @@ import "github.com/waku-org/go-waku/library"
 // (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, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_dns_discovery(url *C.char, nameserver *C.char, ms C.int, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.DNSDiscovery(C.GoString(url), C.GoString(nameserver), int(ms))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Update the bootnode list used for discovering new peers via DiscoveryV5
 // The bootnodes param should contain a JSON array containing the bootnode ENRs i.e. `["enr:...", "enr:..."]`
 //
 //export waku_discv5_update_bootnodes
-func waku_discv5_update_bootnodes(bootnodes *C.char, onErrCb C.WakuCallBack) C.int {
+func waku_discv5_update_bootnodes(bootnodes *C.char, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.SetBootnodes(C.GoString(bootnodes))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
diff --git a/library/c/api_encoding.go b/library/c/api_encoding.go
index 6a9d03d29..a9c38ae96 100644
--- a/library/c/api_encoding.go
+++ b/library/c/api_encoding.go
@@ -4,24 +4,28 @@ package main
 #include <cgo_utils.h>
 */
 import "C"
-import "github.com/waku-org/go-waku/library"
+import (
+	"unsafe"
+
+	"github.com/waku-org/go-waku/library"
+)
 
 // Decode a waku message using a 32 bytes symmetric key. The key must be a hex encoded string with "0x" prefix
 //
 //export waku_decode_symmetric
-func waku_decode_symmetric(messageJSON *C.char, symmetricKey *C.char, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_decode_symmetric(messageJSON *C.char, symmetricKey *C.char, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.DecodeSymmetric(C.GoString(messageJSON), C.GoString(symmetricKey))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Decode a waku message using a secp256k1 private key. The key must be a hex encoded string with "0x" prefix
 //
 //export waku_decode_asymmetric
-func waku_decode_asymmetric(messageJSON *C.char, privateKey *C.char, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_decode_asymmetric(messageJSON *C.char, privateKey *C.char, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.DecodeAsymmetric(C.GoString(messageJSON), C.GoString(privateKey))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Encrypt a message with a secp256k1 public key.
@@ -30,10 +34,10 @@ func waku_decode_asymmetric(messageJSON *C.char, privateKey *C.char, onOkCb C.Wa
 // The message version will be set to 1
 //
 //export waku_encode_asymmetric
-func waku_encode_asymmetric(messageJSON *C.char, publicKey *C.char, optionalSigningKey *C.char, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_encode_asymmetric(messageJSON *C.char, publicKey *C.char, optionalSigningKey *C.char, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.EncodeAsymmetric(C.GoString(messageJSON), C.GoString(publicKey), C.GoString(optionalSigningKey))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Encrypt a message with a 32 bytes symmetric key
@@ -42,8 +46,8 @@ func waku_encode_asymmetric(messageJSON *C.char, publicKey *C.char, optionalSign
 // The message version will be set to 1
 //
 //export waku_encode_symmetric
-func waku_encode_symmetric(messageJSON *C.char, symmetricKey *C.char, optionalSigningKey *C.char, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_encode_symmetric(messageJSON *C.char, symmetricKey *C.char, optionalSigningKey *C.char, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.EncodeSymmetric(C.GoString(messageJSON), C.GoString(symmetricKey), C.GoString(optionalSigningKey))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
diff --git a/library/c/api_filter.go b/library/c/api_filter.go
index 4a7496990..2658ef4e0 100644
--- a/library/c/api_filter.go
+++ b/library/c/api_filter.go
@@ -4,7 +4,11 @@ package main
 #include <cgo_utils.h>
 */
 import "C"
-import "github.com/waku-org/go-waku/library"
+import (
+	"unsafe"
+
+	"github.com/waku-org/go-waku/library"
+)
 
 // Creates a subscription to a filter full node matching a content filter.
 // filterJSON must contain a JSON with this format:
@@ -20,10 +24,10 @@ import "github.com/waku-org/go-waku/library"
 // It returns a json object containing the details of the subscriptions along with any errors in case of partial failures
 //
 //export waku_filter_subscribe
-func waku_filter_subscribe(filterJSON *C.char, peerID *C.char, ms C.int, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_filter_subscribe(filterJSON *C.char, peerID *C.char, ms C.int, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.FilterSubscribe(C.GoString(filterJSON), C.GoString(peerID), int(ms))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Used to know if a service node has an active subscription for this client
@@ -32,9 +36,9 @@ func waku_filter_subscribe(filterJSON *C.char, peerID *C.char, ms C.int, onOkCb
 // (in milliseconds) is reached, or an error will be returned
 //
 //export waku_filter_ping
-func waku_filter_ping(peerID *C.char, ms C.int, onErrCb C.WakuCallBack) C.int {
+func waku_filter_ping(peerID *C.char, ms C.int, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.FilterPing(C.GoString(peerID), int(ms))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
 
 // Sends a requests to a service node to stop pushing messages matching this filter to this client.
@@ -51,9 +55,9 @@ func waku_filter_ping(peerID *C.char, ms C.int, onErrCb C.WakuCallBack) C.int {
 // (in milliseconds) is reached, or an error will be returned
 //
 //export waku_filter_unsubscribe
-func waku_filter_unsubscribe(filterJSON *C.char, peerID *C.char, ms C.int, onErrCb C.WakuCallBack) C.int {
+func waku_filter_unsubscribe(filterJSON *C.char, peerID *C.char, ms C.int, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.FilterUnsubscribe(C.GoString(filterJSON), C.GoString(peerID), int(ms))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
 
 // Sends a requests to a service node (or all service nodes) to stop pushing messages
@@ -63,8 +67,8 @@ func waku_filter_unsubscribe(filterJSON *C.char, peerID *C.char, ms C.int, onErr
 // (in milliseconds) is reached, or an error will be returned
 //
 //export waku_filter_unsubscribe_all
-func waku_filter_unsubscribe_all(peerID *C.char, ms C.int, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_filter_unsubscribe_all(peerID *C.char, ms C.int, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.FilterUnsubscribeAll(C.GoString(peerID), int(ms))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
diff --git a/library/c/api_legacy_filter.go b/library/c/api_legacy_filter.go
index 4c0893f3d..0bdcc396d 100644
--- a/library/c/api_legacy_filter.go
+++ b/library/c/api_legacy_filter.go
@@ -4,7 +4,11 @@ package main
 #include <cgo_utils.h>
 */
 import "C"
-import "github.com/waku-org/go-waku/library"
+import (
+	"unsafe"
+
+	"github.com/waku-org/go-waku/library"
+)
 
 // Creates a subscription to a light node matching a content filter and, optionally, a pubSub topic.
 // filterJSON must contain a JSON with this format:
@@ -23,9 +27,9 @@ import "github.com/waku-org/go-waku/library"
 // (in milliseconds) is reached, or an error will be returned
 //
 //export waku_legacy_filter_subscribe
-func waku_legacy_filter_subscribe(filterJSON *C.char, peerID *C.char, ms C.int, onErrCb C.WakuCallBack) C.int {
+func waku_legacy_filter_subscribe(filterJSON *C.char, peerID *C.char, ms C.int, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.LegacyFilterSubscribe(C.GoString(filterJSON), C.GoString(peerID), int(ms))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
 
 // Removes subscriptions in a light node matching a content filter and, optionally, a pubSub topic.
@@ -44,7 +48,7 @@ func waku_legacy_filter_subscribe(filterJSON *C.char, peerID *C.char, ms C.int,
 // (in milliseconds) is reached, or an error will be returned
 //
 //export waku_legacy_filter_unsubscribe
-func waku_legacy_filter_unsubscribe(filterJSON *C.char, ms C.int, onErrCb C.WakuCallBack) C.int {
+func waku_legacy_filter_unsubscribe(filterJSON *C.char, ms C.int, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.LegacyFilterUnsubscribe(C.GoString(filterJSON), int(ms))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
diff --git a/library/c/api_lightpush.go b/library/c/api_lightpush.go
index 2243f4f1e..fd726dd02 100644
--- a/library/c/api_lightpush.go
+++ b/library/c/api_lightpush.go
@@ -4,7 +4,11 @@ package main
 #include <cgo_utils.h>
 */
 import "C"
-import "github.com/waku-org/go-waku/library"
+import (
+	"unsafe"
+
+	"github.com/waku-org/go-waku/library"
+)
 
 // Publish a message using waku lightpush. Use NULL for topic to use the default pubsub topic..
 // peerID should contain the ID of a peer supporting the lightpush protocol. Use NULL to automatically select a node
@@ -12,8 +16,8 @@ import "github.com/waku-org/go-waku/library"
 // (in milliseconds) is reached, or an error will be returned
 //
 //export waku_lightpush_publish
-func waku_lightpush_publish(messageJSON *C.char, topic *C.char, peerID *C.char, ms C.int, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_lightpush_publish(messageJSON *C.char, topic *C.char, peerID *C.char, ms C.int, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.LightpushPublish(C.GoString(messageJSON), C.GoString(topic), C.GoString(peerID), int(ms))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
diff --git a/library/c/api_relay.go b/library/c/api_relay.go
index 0f84c3ce6..dc680b423 100644
--- a/library/c/api_relay.go
+++ b/library/c/api_relay.go
@@ -4,20 +4,24 @@ package main
 #include <cgo_utils.h>
 */
 import "C"
-import "github.com/waku-org/go-waku/library"
+import (
+	"unsafe"
+
+	"github.com/waku-org/go-waku/library"
+)
 
 // Determine if there are enough peers to publish a message on a topic. Use NULL
 // to verify the number of peers in the default pubsub topic
 //
 //export waku_relay_enough_peers
-func waku_relay_enough_peers(topic *C.char, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_relay_enough_peers(topic *C.char, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		result, err := library.RelayEnoughPeers(C.GoString(topic))
 		if result {
 			return "true", err
 		}
 		return "false", err
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Publish a message using waku relay and returns the message ID. Use NULL for topic to use the default pubsub topic
@@ -25,10 +29,10 @@ func waku_relay_enough_peers(topic *C.char, onOkCb C.WakuCallBack, onErrCb C.Wak
 // (in milliseconds) is reached, or an error will be returned.
 //
 //export waku_relay_publish
-func waku_relay_publish(messageJSON *C.char, topic *C.char, ms C.int, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_relay_publish(messageJSON *C.char, topic *C.char, ms C.int, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.RelayPublish(C.GoString(messageJSON), C.GoString(topic), int(ms))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Subscribe to a WakuRelay topic. Set the topic to NULL to subscribe
@@ -37,25 +41,25 @@ func waku_relay_publish(messageJSON *C.char, topic *C.char, ms C.int, onOkCb C.W
 // the message was received
 //
 //export waku_relay_subscribe
-func waku_relay_subscribe(topic *C.char, onErrCb C.WakuCallBack) C.int {
+func waku_relay_subscribe(topic *C.char, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.RelaySubscribe(C.GoString(topic))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
 
 // Returns a json response with the list of pubsub topics the node
 // is subscribed to in WakuRelay
 //
 //export waku_relay_topics
-func waku_relay_topics(onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_relay_topics(cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.RelayTopics()
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Closes the pubsub subscription to a pubsub topic
 //
 //export waku_relay_unsubscribe
-func waku_relay_unsubscribe(topic *C.char, onErrCb C.WakuCallBack) C.int {
+func waku_relay_unsubscribe(topic *C.char, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	err := library.RelayUnsubscribe(C.GoString(topic))
-	return execErrCB(onErrCb, err)
+	return execErrCB(err, onErrCb, userData)
 }
diff --git a/library/c/api_store.go b/library/c/api_store.go
index 7cf83cc4d..9a292bfd1 100644
--- a/library/c/api_store.go
+++ b/library/c/api_store.go
@@ -4,7 +4,11 @@ package main
 #include <cgo_utils.h>
 */
 import "C"
-import "github.com/waku-org/go-waku/library"
+import (
+	"unsafe"
+
+	"github.com/waku-org/go-waku/library"
+)
 
 // Query historic messages using waku store protocol.
 // queryJSON must contain a valid json string with the following format:
@@ -36,10 +40,10 @@ import "github.com/waku-org/go-waku/library"
 // (in milliseconds) is reached, or an error will be returned
 //
 //export waku_store_query
-func waku_store_query(queryJSON *C.char, peerID *C.char, ms C.int, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_store_query(queryJSON *C.char, peerID *C.char, ms C.int, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.StoreQuery(C.GoString(queryJSON), C.GoString(peerID), int(ms))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
 
 // Query historic messages stored in the localDB using waku store protocol.
@@ -70,8 +74,8 @@ func waku_store_query(queryJSON *C.char, peerID *C.char, ms C.int, onOkCb C.Waku
 // Requires the `store` option to be passed when setting up the initial configuration
 //
 //export waku_store_local_query
-func waku_store_local_query(queryJSON *C.char, onOkCb C.WakuCallBack, onErrCb C.WakuCallBack) C.int {
+func waku_store_local_query(queryJSON *C.char, cb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	return singleFnExec(func() (string, error) {
 		return library.StoreLocalQuery(C.GoString(queryJSON))
-	}, onOkCb, onErrCb)
+	}, cb, userData)
 }
diff --git a/library/c/cgo_utils.c b/library/c/cgo_utils.c
index defe95f17..c31bd804d 100644
--- a/library/c/cgo_utils.c
+++ b/library/c/cgo_utils.c
@@ -4,6 +4,6 @@
 
 // This is a bridge function to execute C callbacks.
 // It's used internally in go-waku. Do not call directly
-void _waku_execCB(WakuCallBack op, char* a, size_t b) {
-    op(a, b);
+void _waku_execCB(WakuCallBack op, char* a, void * user_data) {
+    op(a, user_data);
 }
diff --git a/library/c/cgo_utils.go b/library/c/cgo_utils.go
index 417e830f4..a1b401c46 100644
--- a/library/c/cgo_utils.go
+++ b/library/c/cgo_utils.go
@@ -3,33 +3,32 @@ package main
 /*
 #include <stdlib.h>
 #include <cgo_utils.h>
-extern void _waku_execCB(WakuCallBack op, char* a, size_t b);
+extern void _waku_execCB(WakuCallBack op, char* a, void * b);
 */
 import "C"
 import "unsafe"
 
-func execOkCB(onOkCb C.WakuCallBack, value string) C.int {
+func execOkCB(value string, onOkCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	if onOkCb == nil {
 		return retMissingCallback
 	}
 
 	val := C.CString(value)
-	valLen := C.size_t(len(value))
-	C._waku_execCB(onOkCb, val, valLen)
+	C._waku_execCB(onOkCb, val, userData)
 
 	C.free(unsafe.Pointer(val))
 
 	return retOk
 }
 
-func execErrCB(onErrCb C.WakuCallBack, err error) C.int {
+func execErrCB(err error, onErrCb C.WakuCallBack, userData unsafe.Pointer) C.int {
 	if onErrCb == nil {
 		return retMissingCallback
 	}
 
 	if err != nil {
 		errMsg := err.Error()
-		execOkCB(onErrCb, errMsg) // reusing ok cb
+		execOkCB(errMsg, onErrCb, userData) // reusing ok cb
 		return retErr
 	}
 
diff --git a/library/c/cgo_utils.h b/library/c/cgo_utils.h
index 47582ed29..2e6853be5 100644
--- a/library/c/cgo_utils.h
+++ b/library/c/cgo_utils.h
@@ -1,6 +1,4 @@
 #include <stdlib.h>
 #include <stdint.h>
 
-typedef void (*WakuCallBack) (const char* msg, size_t len_0);
-
-typedef void (*BytesCallBack) (uint8_t* data, size_t len_0);
\ No newline at end of file
+typedef void (*WakuCallBack) (const char* msg, void * user_data);
diff --git a/library/encoding.go b/library/encoding.go
index eefa54b4b..6b6e83dc0 100644
--- a/library/encoding.go
+++ b/library/encoding.go
@@ -137,7 +137,12 @@ func DecodeSymmetric(messageJSON string, symmetricKey string) (string, error) {
 	}
 
 	if msg.Version == 0 {
-		return marshalJSON(msg.Payload)
+		return marshalJSON(struct {
+			Data    []byte `json:"data"`
+			Padding []byte `json:"padding"`
+		}{
+			Data: msg.Payload,
+		})
 	} else if msg.Version > 1 {
 		return "", errors.New("unsupported wakumessage version")
 	}
@@ -182,7 +187,12 @@ func DecodeAsymmetric(messageJSON string, privateKey string) (string, error) {
 	}
 
 	if msg.Version == 0 {
-		return marshalJSON(msg.Payload)
+		return marshalJSON(struct {
+			Data    []byte `json:"data"`
+			Padding []byte `json:"padding"`
+		}{
+			Data: msg.Payload,
+		})
 	} else if msg.Version > 1 {
 		return "", errors.New("unsupported wakumessage version")
 	}
diff --git a/library/node.go b/library/node.go
index a3da4f03d..e2644ef5b 100644
--- a/library/node.go
+++ b/library/node.go
@@ -382,5 +382,16 @@ func Peers() (string, error) {
 		return "", err
 	}
 
+	for _, p := range peers {
+		addrs := []multiaddr.Multiaddr{}
+		for i := range p.Addrs {
+			_, err := p.Addrs[i].ValueForProtocol(multiaddr.P_SNI)
+			if err != nil {
+				addrs = append(addrs, p.Addrs[i])
+			}
+		}
+		p.Addrs = addrs
+	}
+
 	return marshalJSON(peers)
 }
diff --git a/library/signals.c b/library/signals.c
index 8733fbc5b..297ef1905 100644
--- a/library/signals.c
+++ b/library/signals.c
@@ -7,12 +7,12 @@
 #include <stdbool.h>
 #include "_cgo_export.h"
 
-typedef void (*callback)(const char *jsonEvent, size_t len_0);
+typedef void (*callback)(const char *jsonEvent);
 callback gCallback = 0;
 
-bool ServiceSignalEvent(const char *jsonEvent, size_t len_0) {
+bool ServiceSignalEvent(const char *jsonEvent) {
 	if (gCallback) {
-		gCallback(jsonEvent, len_0);
+		gCallback(jsonEvent);
 	}
 
 	return true;