add tools::http for generic HTTP GET and move HttpsConnector there

...to avoid having the tools:: module depend on api2.

The get_string function is based directly on hyper and thus relatively
simple, not supporting redirects for example.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>

src/tools/http.rs

@@ -0,0 +1,100 @@
+use anyhow::{Error, format_err, bail};
+use lazy_static::lazy_static;
+use std::task::{Context, Poll};
+use std::os::unix::io::AsRawFd;
+
+use hyper::{Uri, Body};
+use hyper::client::{Client, HttpConnector};
+use openssl::ssl::{SslConnector, SslMethod};
+use futures::*;
+
+use crate::tools::{
+    async_io::EitherStream,
+    socket::{
+        set_tcp_keepalive,
+        PROXMOX_BACKUP_TCP_KEEPALIVE_TIME,
+    },
+};
+
+lazy_static! {
+    static ref HTTP_CLIENT: Client<HttpsConnector, Body> = {
+        let connector = SslConnector::builder(SslMethod::tls()).unwrap().build();
+        let httpc = HttpConnector::new();
+        let https = HttpsConnector::with_connector(httpc, connector);
+        Client::builder().build(https)
+    };
+}
+
+pub async fn get_string<U: AsRef<str>>(uri: U) -> Result<String, Error> {
+    let res = HTTP_CLIENT.get(uri.as_ref().parse()?).await?;
+
+    let status = res.status();
+    if !status.is_success() {
+        bail!("Got bad status '{}' from server", status)
+    }
+
+    let buf = hyper::body::to_bytes(res).await?;
+    String::from_utf8(buf.to_vec())
+        .map_err(|err| format_err!("Error converting HTTP result data: {}", err))
+}
+
+#[derive(Clone)]
+pub struct HttpsConnector {
+    http: HttpConnector,
+    ssl_connector: std::sync::Arc<SslConnector>,
+}
+
+impl HttpsConnector {
+    pub fn with_connector(mut http: HttpConnector, ssl_connector: SslConnector) -> Self {
+        http.enforce_http(false);
+
+        Self {
+            http,
+            ssl_connector: std::sync::Arc::new(ssl_connector),
+        }
+    }
+}
+
+type MaybeTlsStream = EitherStream<
+    tokio::net::TcpStream,
+    tokio_openssl::SslStream<tokio::net::TcpStream>,
+>;
+
+impl hyper::service::Service<Uri> for HttpsConnector {
+    type Response = MaybeTlsStream;
+    type Error = Error;
+    type Future = std::pin::Pin<Box<
+        dyn Future<Output = Result<Self::Response, Self::Error>> + Send + 'static
+    >>;
+
+    fn poll_ready(&mut self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        // This connector is always ready, but others might not be.
+        Poll::Ready(Ok(()))
+    }
+
+    fn call(&mut self, dst: Uri) -> Self::Future {
+        let mut this = self.clone();
+        async move {
+            let is_https = dst
+                .scheme()
+                .ok_or_else(|| format_err!("missing URL scheme"))?
+                == "https";
+            let host = dst
+                .host()
+                .ok_or_else(|| format_err!("missing hostname in destination url?"))?
+                .to_string();
+
+            let config = this.ssl_connector.configure();
+            let conn = this.http.call(dst).await?;
+
+            let _ = set_tcp_keepalive(conn.as_raw_fd(), PROXMOX_BACKUP_TCP_KEEPALIVE_TIME);
+
+            if is_https {
+                let conn = tokio_openssl::connect(config?, &host, conn).await?;
+                Ok(MaybeTlsStream::Right(conn))
+            } else {
+                Ok(MaybeTlsStream::Left(conn))
+            }
+        }.boxed()
+    }
+}