feat(dns): Implement resolving /dnsaddr for wasm target

Cargo.toml

@@ -54,6 +54,7 @@ members = [
     "swarm-test",
     "swarm",
     "transports/dns",
+    "transports/dns-websys",
     "transports/noise",
     "transports/plaintext",
     "transports/pnet",
@@ -82,6 +83,7 @@ libp2p-connection-limits = { version = "0.7.0", path = "misc/connection-limits"
 libp2p-core = { version = "0.44.0", path = "core" }
 libp2p-dcutr = { version = "0.15.0", path = "protocols/dcutr" }
 libp2p-dns = { version = "0.45.0", path = "transports/dns" }
+libp2p-dns-websys = { version = "0.1.0-alpha", path = "transports/dns-websys" }
 libp2p-floodsub = { version = "0.48.0", path = "protocols/floodsub" }
 libp2p-gossipsub = { version = "0.50.0", path = "protocols/gossipsub" }
 libp2p-identify = { version = "0.48.0", path = "protocols/identify" }

transports/dns-websys/CHANGELOG.md

@@ -0,0 +1,9 @@
+## 0.1.0-alpha
+
+- Support DNS transport for wasm32 targets that resolves DNS components over DNS-over-HTTPS (DoH).
+  `/dnsaddr` is always resolved, however `/dns`, `/dns4` and `/dns6` are governed by the
+  `DnsResolution` policy (default to `DnsResolutionAuto`): addresses containing a explicit protocols
+  (i.e. `webrtc-direct`) are resolved to `/ip4`/`/ip6`, while the rest are passed through to the inner
+  transport unchanged, since browsers resolve those hostnames natively and need
+  the hostname preserved for SNI.
+  See [PR XXXX](https://github.com/libp2p/rust-libp2p/pull/XXXX).

transports/dns-websys/Cargo.toml

@@ -0,0 +1,32 @@
+[package]
+name = "libp2p-dns-websys"
+edition.workspace = true
+rust-version = { workspace = true }
+description = "DNS transport implementation via DNS-over-HTTPS for libp2p under WASM environment"
+version = "0.1.0-alpha"
+license = "MIT"
+repository = "https://github.com/libp2p/rust-libp2p"
+keywords = ["peer-to-peer", "libp2p", "networking"]
+categories = ["network-programming", "asynchronous"]
+
+[dependencies]
+futures = { workspace = true }
+js-sys = "0.3.77"
+libp2p-core = { workspace = true }
+parking_lot = "0.12.5"
+send_wrapper = { version = "0.6.0", features = ["futures"] }
+serde = { version = "1.0.228", features = ["derive"] }
+serde_json = "1.0.150"
+smallvec = "1.15.1"
+thiserror = { workspace = true }
+tracing = { workspace = true }
+url = "2.5.4"
+wasm-bindgen = "0.2.100"
+wasm-bindgen-futures = { workspace = true }
+web-sys = { version = "0.3.77", features = ["AbortSignal", "Headers", "Request", "RequestInit", "Response", "Window", "WorkerGlobalScope"] }
+
+[package.metadata.docs.rs]
+all-features = true
+
+[lints]
+workspace = true