Add transport support for dnsaddr #1450
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different generator has their own types
transports/dns/src/lib.rs
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| @@ -170,7 +176,56 @@ where | |||
| }) | |||
| .next() | |||
| .ok_or_else(|| DnsErr::ResolveFail(name)) | |||
| }.left_future() | |||
| }.boxed().left_future() | |||
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You normally don't have to box the future. Just put an async block around the entire code instead of having two distinct async blocks.
Since this is a lot of code, it might be worth moving it to a separate freestanding function.
| assert_eq!(addr.len(), 3); | ||
| // TODO: ipfs | ||
| // match addr[2] { | ||
| // Protocol::Ipfs(_) => (), |
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I'll file another PR to add the ipfs support.
transports/dns/src/lib.rs
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| use trust_dns_client::udp::UdpClientConnection; | ||
| use trust_dns_client::client::{SyncClient, Client}; | ||
| use trust_dns_proto::rr::domain::Name; | ||
| use futures::stream::FuturesOrdered; |
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Please merge with the use futures:: above.
transports/dns/src/lib.rs
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| @@ -238,6 +225,90 @@ where TErr: error::Error + 'static | |||
| } | |||
| } | |||
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| async fn resolve_dns<T>(p: Protocol<'_>, suffix: Multiaddr) -> Result<Multiaddr, DnsErr<T::Error>> | |||
| where | |||
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These where bounds shouldn't be necessary.
| where |
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Updated at fcc3d6a .
If T: Transport is removed we'll get the error:
error[E0220]: associated type `Error` not found for `T`
--> transports/dns/src/lib.rs:228:89
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228 | async fn resolve_dns<T>(p: Protocol<'_>, suffix: Multiaddr) -> Result<Multiaddr, DnsErr<T::Error>>
| ^^^^^^^^ associated type `Error` not found
transports/dns/src/lib.rs
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| { | ||
| match p { | ||
| Protocol::Dns4(ref n) | Protocol::Dns6(ref n) => { | ||
| let name = n.to_string(); |
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| let name = n.to_string(); |
transports/dns/src/lib.rs
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| T::Dial: Send | ||
| { | ||
| match p { | ||
| Protocol::Dns4(ref n) | Protocol::Dns6(ref n) => { |
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| Protocol::Dns4(ref n) | Protocol::Dns6(ref n) => { | |
| Protocol::Dns4(ref name) | Protocol::Dns6(ref name) => { |
transports/dns/src/lib.rs
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| Err(e) => Err(e) | ||
| }.map_err(|_| { | ||
| error!("DNS resolver crashed"); | ||
| DnsErr::ResolveFail(name.clone()) |
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| DnsErr::ResolveFail(name.clone()) | |
| DnsErr::ResolveFail(name.to_string()) |
transports/dns/src/lib.rs
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| if suffix.len() == 0 { | ||
| Ok(resolved_addrs[0].clone()) | ||
| } else { | ||
| // TODO: suffix matching |
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I'd that this is out of scope of this function.
| } | ||
| Protocol::Dnsaddr(ref n) => { | ||
| let conn = UdpClientConnection::new("8.8.8.8:53".parse().unwrap()).unwrap(); // TODO: error handling | ||
| let client = SyncClient::new(conn); // TODO: should use async client? |
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// TODO: should use async client?
Yes!
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Hmm...
I've added trust-dns in order to query TXT records. I'm trying to switch the SyncClient to AsyncClient but I think AsyncClient can not be used for rust-libp2p because a background future is required for the client. 🤔
https://docs.rs/trust-dns-client/0.19.3/trust_dns_client/#async-usage
// Create a new client, the bg is a background future which handles
// the multiplexing of the DNS requests to the server.
// the client is a handle to an unbounded queue for sending requests via the
// background. The background must be scheduled to run before the client can
// send any dns requests
let client = AsyncClient::connect(stream);
// await the connection to be established
let (mut client, bg) = runtime.block_on(client).expect("connection failed");
// make sure to run the background task
runtime.spawn(bg);======
Do you know other library what can query TXT records asynchronously? 💦
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I think AsyncClient can not be used for rust-libp2p because a background future is required for the client.
That makes it more difficult to implement, but normally not impossible.
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The idea is not to run the background future in the background, but to run it alongside with the "front" one. I don't have more precise guidelines without looking deeply into details (which I don't really have the time right now to do) though.
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I've thought for a while about this but I can not come up anything to address the issue... hmm... 🤔💦
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Superseded by #1931. |
Related issue: #967
Related PR: #1356
https://github.com/multiformats/multiaddr/blob/master/protocols/DNSADDR.md