beast: websocket handshake differs from curl output, fails with obscure server

beast version 67

note I have replaced the host with [host] throughout, I can privately share the real host to help testing

I’m using this curl command to handshake with a server based on a pascal websocket server (http://www.esegece.com/websockets/)

curl -v -i -N -H "Connection: Upgrade" -H "Upgrade: websocket" -H "Host: [host]" -H "Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==" -H "Sec-WebSocket-Version: 13" https://[host]

I am trying to do the same handshake with beast, even copying the curl headers:

        beast::websocket::response_type res;
        ws.handshake_ex(res, host, "/",
                        [](beast::websocket::request_type &m)
                        {
                            m.insert(beast::http::field::accept, "*/*");
                            m.insert(beast::http::field::user_agent, "curl/7.47.0");
                            std::cout << m << std::endl;
                        },
                        ec);

        std::cout << res << std::endl;

the server accepts the curl connection but rejects the beast connection. the server’s logs show that the headers are received with extra newlines or something like newlines in the case of beast:

server logs for curl connection:

Recv: GET / HTTP/1.1
Host: [host]
User-Agent: curl/7.47.0
Accept: */*
Connection: Upgrade
Upgrade: websocket
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Sec-WebSocket-Version: 13

Sent: HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
Server: sgcWebSockets 3.5

server logs for beast:

Recv: GET
Recv:  /
Recv:  HTTP/1.1

Recv: Host: [host]

Recv: Upgrade: websocket

Recv: Connection: upgrade

Recv: Sec-WebSocket-Key: lD7oPd7/ryIbKDcgimpDAA==

Recv: Sec-WebSocket-Version: 13

Recv: Accept: */*

Recv: User-Agent: curl/7.47.0

Recv: 

Sent: HTTP/1.1 302 Moved Temporarily
Connection: close
Content-Length: 0
Date: Tue, 27 Jun 2017 17:01:11 GMT
Server: sgcWebSockets 3.5
Location: login
Set-Cookie: IDHTTPSESSIONID=ANv2nTA6vZ8PuVx; Path=/

I also tested beast using mitmproxy (https://mitmproxy.org/) instead of connecting to the server directly, and it works correctly in this case, as I assume mitmproxy is putting the headers together. I assume my problem has to do with the extra newlines in the beast output. This may be standards-compliant (I don’t know), but it’s making my server unhappy. Is there a way to change this?