Requesting BIP353 address from peer (#683)

The peer will only answer if there is a channel.

Optionally pass an IETF BCP 47 language tag (en, fr, de, es, ...) to indicate preference for the words that make up the address.

src/commonMain/kotlin/fr/acinq/lightning/io/Peer.kt

@@ -12,6 +12,7 @@ import fr.acinq.lightning.blockchain.fee.FeeratePerKw
 import fr.acinq.lightning.blockchain.fee.OnChainFeerates
 import fr.acinq.lightning.blockchain.mempool.MempoolSpaceClient
 import fr.acinq.lightning.channel.*
+import fr.acinq.lightning.channel.ChannelCommand.Commitment.Splice.Response
 import fr.acinq.lightning.channel.states.*
 import fr.acinq.lightning.crypto.noise.*
 import fr.acinq.lightning.db.*
@@ -117,6 +118,8 @@ data class ChannelClosing(val channelId: ByteVector32) : PeerEvent()
  */
 data class PhoenixAndroidLegacyInfoEvent(val info: PhoenixAndroidLegacyInfo) : PeerEvent()
 
+data class AddressAssigned(val address: String) : PeerEvent()
+
 /**
  * The peer we establish a connection to. This object contains the TCP socket, a flow of the channels with that peer, and watches
  * the events on those channels and processes the relevant actions. The dialogue with the peer is done in coroutines.
@@ -712,6 +715,25 @@ class Peer(
         peerConnection?.send(message)
     }
 
+    /**
+     * Request a BIP-353's compliant DNS address from our peer.
+     *
+     * This will only return if there are existing channels with the peer, otherwise it will hang. This should be handled by the caller.
+     *
+     * @param languageSubtag IETF BCP 47 language tag (en, fr, de, es, ...) to indicate preference for the words that make up the address
+     */
+    suspend fun requestAddress(languageSubtag: String): String {
+        val replyTo = CompletableDeferred<String>()
+        this.launch {
+            eventsFlow
+                .filterIsInstance<AddressAssigned>()
+                .first()
+                .let { event -> replyTo.complete(event.address) }
+        }
+        peerConnection?.send(DNSAddressRequest(nodeParams.chainHash, nodeParams.defaultOffer(walletParams.trampolineNode.id).first, languageSubtag))
+        return replyTo.await()
+    }
+
     sealed class SelectChannelResult {
         /** We have a channel that is available for payments and splicing. */
         data class Available(val channel: Normal) : SelectChannelResult()
@@ -1188,6 +1210,10 @@ class Peer(
                             }
                         }
                     }
+                    is DNSAddressResponse -> {
+                        logger.info { "bip353 dns address assigned: ${msg.address}" }
+                        _eventsFlow.emit(AddressAssigned(msg.address))
+                    }
                 }
             }
             is WatchReceived -> {

src/commonMain/kotlin/fr/acinq/lightning/wire/LightningMessages.kt

@@ -14,6 +14,8 @@ import fr.acinq.lightning.logging.*
 import fr.acinq.lightning.router.Announcements
 import fr.acinq.lightning.utils.*
 import fr.acinq.secp256k1.Hex
+import io.ktor.utils.io.charsets.*
+import io.ktor.utils.io.core.*
 import kotlin.math.max
 import kotlin.math.min
 
@@ -81,6 +83,8 @@ interface LightningMessage {
                 PayToOpenResponse.type -> PayToOpenResponse.read(stream)
                 FCMToken.type -> FCMToken.read(stream)
                 UnsetFCMToken.type -> UnsetFCMToken
+                DNSAddressRequest.type -> DNSAddressRequest.read(stream)
+                DNSAddressResponse.type -> DNSAddressResponse.read(stream)
                 PhoenixAndroidLegacyInfo.type -> PhoenixAndroidLegacyInfo.read(stream)
                 PleaseOpenChannel.type -> PleaseOpenChannel.read(stream)
                 Stfu.type -> Stfu.read(stream)
@@ -1747,6 +1751,59 @@ data class PhoenixAndroidLegacyInfo(
     }
 }
 
+/**
+ * A message to request a BIP-353's compliant DNS address from our peer. The peer may not respond, e.g. if there are no channels.
+ *
+ * @param languageSubtag IETF BCP 47 language tag (en, fr, de, es, ...) to indicate preference for the words that make up the address
+ */
+data class DNSAddressRequest(override val chainHash: BlockHash, val offer: OfferTypes.Offer, val languageSubtag: String) : LightningMessage, HasChainHash {
+
+    override val type: Long get() = DNSAddressRequest.type
+
+    override fun write(out: Output) {
+        LightningCodecs.writeBytes(chainHash.value, out)
+        val serializedOffer = OfferTypes.Offer.tlvSerializer.write(offer.records)
+        LightningCodecs.writeU16(serializedOffer.size, out)
+        LightningCodecs.writeBytes(serializedOffer, out)
+        LightningCodecs.writeU16(languageSubtag.length, out)
+        LightningCodecs.writeBytes(languageSubtag.toByteArray(charset = Charsets.UTF_8), out)
+    }
+
+    companion object : LightningMessageReader<DNSAddressRequest> {
+        const val type: Long = 35025
+
+        override fun read(input: Input): DNSAddressRequest {
+            return DNSAddressRequest(
+                chainHash = BlockHash(LightningCodecs.bytes(input, 32)),
+                offer = OfferTypes.Offer(OfferTypes.Offer.tlvSerializer.read(LightningCodecs.bytes(input, LightningCodecs.u16(input)))),
+                languageSubtag = LightningCodecs.bytes(input, LightningCodecs.u16(input)).decodeToString()
+            )
+        }
+    }
+}
+
+data class DNSAddressResponse(override val chainHash: BlockHash, val address: String) : LightningMessage, HasChainHash {
+
+    override val type: Long get() = DNSAddressResponse.type
+
+    override fun write(out: Output) {
+        LightningCodecs.writeBytes(chainHash.value, out)
+        LightningCodecs.writeU16(address.length, out)
+        LightningCodecs.writeBytes(address.toByteArray(charset = Charsets.UTF_8), out)
+    }
+
+    companion object : LightningMessageReader<DNSAddressResponse> {
+        const val type: Long = 35027
+
+        override fun read(input: Input): DNSAddressResponse {
+            return DNSAddressResponse(
+                chainHash = BlockHash(LightningCodecs.bytes(input, 32)),
+                address = LightningCodecs.bytes(input, LightningCodecs.u16(input)).decodeToString()
+            )
+        }
+    }
+}
+
 /**
  * This message is used to request a channel open from a remote node, with local contributions to the funding transaction.
  * If the remote node won't open a channel, it will respond with [PleaseOpenChannelRejected].

src/commonTest/kotlin/fr/acinq/lightning/wire/LightningCodecsTestsCommon.kt

@@ -17,6 +17,7 @@ import fr.acinq.lightning.tests.utils.LightningTestSuite
 import fr.acinq.lightning.utils.msat
 import fr.acinq.lightning.utils.sat
 import fr.acinq.lightning.utils.toByteVector
+import fr.acinq.lightning.wire.OfferTypes.Offer
 import fr.acinq.secp256k1.Hex
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.jsonArray
@@ -874,4 +875,19 @@ class LightningCodecsTestsCommon : LightningTestSuite() {
         val onionMessage = OnionMessages.buildMessage(randomKey(), randomKey(), listOf(), OnionMessages.Destination.Recipient(EncodedNodeId(randomKey().publicKey()), null), TlvStream.empty()).right!!
         assertEquals(onionMessage, OnionMessage.read(onionMessage.write()))
     }
+
+    @Test
+    fun `encode and decode dns address request`() {
+        val encoded = "lno1qgsyxjtl6luzd9t3pr62xr7eemp6awnejusgf6gw45q75vcfqqqqqqqgqyeq5ym0venx2u3qwa5hg6pqw96kzmn5d968jys3v9kxjcm9gp3xjemndphhqtnrdak3gqqkyypsmuhrtwfzm85mht4a3vcp0yrlgua3u3m5uqpc6kf7nqjz6v70qwg"
+        val offer = Offer.decode(encoded).get()
+
+        val msg = DNSAddressRequest(Chain.Testnet.chainHash, offer, "en")
+        assertEquals(msg, LightningMessage.decode(LightningMessage.encode(msg)))
+    }
+
+    @Test
+    fun `encode and decode dns address response`() {
+        val msg = DNSAddressResponse(Chain.Testnet.chainHash, "[email protected]")
+        assertEquals(msg, LightningMessage.decode(LightningMessage.encode(msg)))
+    }
 }