Include Host header for CONNECT proxy requests (#714)

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Include `Host` header for `CONNECT` proxy requests ([#714])
 
 ## [0.9.8] - 2020-05-02
 ### Fixed

src/ConnectionRequest.jl

@@ -126,7 +126,10 @@ sockettype(url::URI, default) = url.scheme in ("wss", "https") ? SSLContext : de
 function connect_tunnel(io, target_url, req)
     target = "$(URIs.hoststring(target_url.host)):$(target_url.port)"
     @debug 1 "📡  CONNECT HTTPS tunnel to $target"
-    headers = Dict(filter(x->x.first == "Proxy-Authorization", req.headers))
+    headers = Dict("Host" => target)
+    if (auth = header(req, "Proxy-Authorization"); !isempty(auth))
+        headers["Proxy-Authorization"] = auth
+    end
     request = Request("CONNECT", target, headers)
     writeheaders(io, request)
     startread(io)

test/client.jl

@@ -408,3 +408,33 @@ end
         test(HTTP.delete(uri, headers, body; query=query), "DELETE")
     end
 end
+
+@testset "HTTP CONNECT Proxy" begin
+    @testset "Host header" begin
+        # Stores the http request passed by the client
+        req = String[]
+
+        # Trivial implementation of a proxy server
+        # We are only interested in the request passed in by the client
+        # Returns 400 after reading the http request into req
+        proxy = listen(IPv4(0), 8082)
+        @async begin
+            sock = accept(proxy)
+            while isopen(sock)
+                line = readline(sock)
+                isempty(line) && break
+
+                push!(req, line)
+            end
+            write(sock, "HTTP/1.1 400 Bad Request\r\n\r\n")
+        end
+
+        # Make the HTTP request
+        HTTP.get("https://example.com"; proxy="http://localhost:8082", retry=false, status_exception=false)
+
+        # Test if the host header exist in the request
+        @test "Host: example.com:443" in req
+
+        close(proxy)
+    end
+end