Try to fix cookie issue: concatenate multiple cookie headers

Dockerfile

@@ -1,4 +1,4 @@
-FROM rust:1.57-bullseye as builder
+FROM rust:1.58-buster as builder
 
 RUN apt-get update && \
     apt-get install -y libssl-dev pkg-config

src/reverse_proxy.rs

@@ -72,22 +72,34 @@ fn create_proxied_request<B>(
 		.uri(forward_uri(forward_url, &request)?)
 		.version(hyper::Version::HTTP_11);
 
-	*builder.headers_mut().unwrap() = remove_hop_headers(request.headers());
+	let headers = builder.headers_mut().unwrap();
+
+	*headers = remove_hop_headers(request.headers());
 
 	// If request does not have host header, add it from original URI authority
-	if let header::Entry::Vacant(entry) = builder.headers_mut().unwrap().entry(header::HOST) {
+	if let header::Entry::Vacant(entry) = headers.entry(header::HOST) {
 		if let Some(authority) = request.uri().authority() {
 			entry.insert(authority.as_str().parse()?);
 		}
 	}
 
+	// Concatenate cookie headers into single header
+	// (HTTP/2 allows several cookie headers, but we are proxying to
+	// HTTP/1.1 that does not)
+	let mut cookie_concat = vec![];
+	while let Some(cookie) = headers.remove(header::COOKIE) {
+		if !cookie_concat.is_empty() {
+			cookie_concat.extend(b"; ");
+		}
+		cookie_concat.extend_from_slice(cookie.as_bytes());
+	}
+	if !cookie_concat.is_empty() {
+		headers.insert(header::COOKIE, cookie_concat.try_into()?);
+	}
+
 	// Add forwarding information in the headers
 	let x_forwarded_for_header_name = "x-forwarded-for";
-	match builder
-		.headers_mut()
-		.unwrap()
-		.entry(x_forwarded_for_header_name)
-	{
+	match headers.entry(x_forwarded_for_header_name) {
 		header::Entry::Vacant(entry) => {
 			entry.insert(client_ip.to_string().parse()?);
 		}
@@ -98,7 +110,7 @@ fn create_proxied_request<B>(
 		}
 	}
 
-	builder.headers_mut().unwrap().insert(
+	headers.insert(
 		HeaderName::from_bytes(b"x-forwarded-proto")?,
 		"https".try_into()?,
 	);
@@ -107,14 +119,8 @@ fn create_proxied_request<B>(
 	if let Some(conn) = request.headers().get(header::CONNECTION) {
 		if conn.to_str()?.to_lowercase() == "upgrade" {
 			if let Some(upgrade) = request.headers().get(header::UPGRADE) {
-				builder
-					.headers_mut()
-					.unwrap()
-					.insert(header::CONNECTION, "Upgrade".try_into()?);
-				builder
-					.headers_mut()
-					.unwrap()
-					.insert(header::UPGRADE, upgrade.clone());
+				headers.insert(header::CONNECTION, "Upgrade".try_into()?);
+				headers.insert(header::UPGRADE, upgrade.clone());
 			}
 		}
 	}