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use tokio::net::UnixStream;
use tonic::transport::{Channel, Endpoint};
fn url_wants_wait_connect(url: &url::Url) -> bool {
url.query_pairs()
.filter(|(k, v)| k == "wait-connect" && v == "1")
.count()
> 0
}
/// Turn a [url::Url] to a [Channel] if it can be parsed successfully.
/// It supports the following schemes (and URLs):
/// - `grpc+http://[::1]:8000`, connecting over unencrypted HTTP/2 (h2c)
/// - `grpc+https://[::1]:8000`, connecting over encrypted HTTP/2
/// - `grpc+unix:/path/to/socket`, connecting to a unix domain socket
///
/// All URLs support adding `wait-connect=1` as a URL parameter, in which case
/// the connection is established lazily.
pub async fn channel_from_url(url: &url::Url) -> Result<Channel, self::Error> {
match url.scheme() {
"grpc+unix" => {
if url.host_str().is_some() {
return Err(Error::HostSetForUnixSocket());
}
let connector = tower::service_fn({
let url = url.clone();
move |_: tonic::transport::Uri| UnixStream::connect(url.path().to_string().clone())
});
// the URL doesn't matter
let endpoint = Endpoint::from_static("http://[::]:50051");
if url_wants_wait_connect(url) {
Ok(endpoint.connect_with_connector(connector).await?)
} else {
Ok(endpoint.connect_with_connector_lazy(connector))
}
}
_ => {
// ensure path is empty, not supported with gRPC.
if !url.path().is_empty() {
return Err(Error::PathMayNotBeSet());
}
// Stringify the URL and remove the grpc+ prefix.
// We can't use `url.set_scheme(rest)`, as it disallows
// setting something http(s) that previously wasn't.
let unprefixed_url_str = match url.to_string().strip_prefix("grpc+") {
None => return Err(Error::MissingGRPCPrefix()),
Some(url_str) => url_str.to_owned(),
};
// Use the regular tonic transport::Endpoint logic, but unprefixed_url_str,
// as tonic doesn't know about grpc+http[s].
let endpoint = Endpoint::try_from(unprefixed_url_str)?;
if url_wants_wait_connect(url) {
Ok(endpoint.connect().await?)
} else {
Ok(endpoint.connect_lazy())
}
}
}
}
/// Errors occuring when trying to connect to a backend
#[derive(Debug, thiserror::Error)]
pub enum Error {
#[error("grpc+ prefix is missing from URL")]
MissingGRPCPrefix(),
#[error("host may not be set for unix domain sockets")]
HostSetForUnixSocket(),
#[error("path may not be set")]
PathMayNotBeSet(),
#[error("transport error: {0}")]
TransportError(tonic::transport::Error),
}
impl From<tonic::transport::Error> for Error {
fn from(value: tonic::transport::Error) -> Self {
Self::TransportError(value)
}
}
#[cfg(test)]
mod tests {
use super::channel_from_url;
use test_case::test_case;
use url::Url;
/// Correct scheme to connect to a unix socket.
#[test_case("grpc+unix:///path/to/somewhere", true; "grpc valid unix socket")]
/// Connecting with wait-connect set to 0 succeeds, as that's the default.
#[test_case("grpc+unix:///path/to/somewhere?wait-connect=0", true; "grpc valid unix wait-connect=0")]
/// Connecting with wait-connect set to 1 fails, as the path doesn't exist.
#[test_case("grpc+unix:///path/to/somewhere?wait-connect=1", false; "grpc valid unix wait-connect=1")]
/// Correct scheme for unix socket, but setting a host too, which is invalid.
#[test_case("grpc+unix://host.example/path/to/somewhere", false; "grpc invalid unix socket and host")]
/// Correct scheme to connect to localhost, with port 12345
#[test_case("grpc+http://[::1]:12345", true; "grpc valid IPv6 localhost port 12345")]
/// Correct scheme to connect to localhost over http, without specifying a port.
#[test_case("grpc+http://localhost", true; "grpc valid http host without port")]
/// Correct scheme to connect to localhost over http, without specifying a port.
#[test_case("grpc+https://localhost", true; "grpc valid https host without port")]
/// Correct scheme to connect to localhost over http, but with additional path, which is invalid.
#[test_case("grpc+http://localhost/some-path", false; "grpc valid invalid host and path")]
/// Connecting with wait-connect set to 0 succeeds, as that's the default.
#[test_case("grpc+http://localhost?wait-connect=0", true; "grpc valid host wait-connect=0")]
/// Connecting with wait-connect set to 1 fails, as the host doesn't exist.
#[test_case("grpc+http://nonexist.invalid?wait-connect=1", false; "grpc valid host wait-connect=1")]
#[tokio::test]
async fn test_from_addr_tokio(uri_str: &str, is_ok: bool) {
let url = Url::parse(uri_str).expect("must parse");
assert_eq!(channel_from_url(&url).await.is_ok(), is_ok)
}
}
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