Add a lightning-dns-resolver crate which answers bLIP 32 queries

When a lightning node wishes to send payments to a BIP 353 human
readable name (using BOLT 12), it first has to resolve that name to
a DNS TXT record. bLIP 32 defines a way to do so over onion
messages, and this completes our implementation thereof by adding
the server side.

It operates by simply accepting new messages and spawning tokio
tasks to do DNS lookups using the `dnsse_prover` crate. It also
contains full end-to-end tests of the BIP 353 -> BOLT 12 -> payment
logic using the new server code to do the resolution.

Note that because we now have a workspace crate which sets the
"lightning/dnssec" feature in its `dev-dependencies`, a naive
`cargo test` will test the "dnssec" feature.

Author: TheBlueMatt

.gitignore

@@ -12,5 +12,6 @@ lightning/net_graph-*.bin
 lightning-rapid-gossip-sync/res/full_graph.lngossip
 lightning-custom-message/target
 lightning-transaction-sync/target
+lightning-dns-resolver/target
 no-std-check/target
 msrv-no-dev-deps-check/target

Cargo.toml

@@ -15,6 +15,7 @@ members = [
     "lightning-custom-message",
     "lightning-transaction-sync",
     "lightning-macros",
+    "lightning-dns-resolver",
     "possiblyrandom",
 ]
 

ci/ci-tests.sh

@@ -54,6 +54,7 @@ WORKSPACE_MEMBERS=(
 	lightning-custom-message
 	lightning-transaction-sync
 	lightning-macros
+	lightning-dns-resolver
 	possiblyrandom
 )
 
@@ -64,10 +65,6 @@ for DIR in "${WORKSPACE_MEMBERS[@]}"; do
 	cargo doc -p "$DIR" --document-private-items
 done
 
-echo -e "\n\nChecking and testing lightning crate with dnssec feature"
-cargo test -p lightning --verbose --color always --features dnssec
-cargo check -p lightning --verbose --color always --features dnssec
-
 echo -e "\n\nChecking and testing Block Sync Clients with features"
 
 cargo test -p lightning-block-sync --verbose --color always --features rest-client

lightning-dns-resolver/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "lightning-dns-resolver"
+version = "0.1.0"
+authors = ["Matt Corallo"]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/lightningdevkit/rust-lightning/"
+description = "A crate which implements DNSSEC resolution for lightning clients over bLIP 32 using `tokio` and the `dnssec-prover` crate."
+edition = "2021"
+
+[dependencies]
+lightning = { version = "0.0.124", path = "../lightning", default-features = false }
+dnssec-prover = { version = "0.6", default-features = false, features = [ "std", "tokio" ] }
+tokio = { version = "1.0", default-features = false, features = ["rt"] }
+
+[dev-dependencies]
+bitcoin = { version = "0.32" }
+tokio = { version = "1.0", default-features = false, features = ["macros", "time"] }
+lightning = { version = "0.0.124", path = "../lightning", features = ["dnssec", "_test_utils"] }