From 478e9f340fe303f3171f4184f494947bf39e3dbf Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Tue, 10 Jan 2023 20:14:48 +0100
Subject: Forwarding subprotocol and target to target websocket

---
 websocket.h | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

(limited to 'websocket.h')

diff --git a/websocket.h b/websocket.h
index 85492f2..951155e 100644
--- a/websocket.h
+++ b/websocket.h
@@ -47,6 +47,8 @@ class websocket_session: public std::enable_shared_from_this<websocket_session>
  boost::beast::flat_buffer buffer_out_;
  std::string host_;
  std::string port_;
+ std::string subprotocol_;
+ std::string relative_target_;
 
 public:
  explicit websocket_session(boost::asio::io_context& ioc, beast::ssl_stream<beast::tcp_stream>&& stream, const std::string& websocket_address):
@@ -55,17 +57,32 @@ public:
   ws_in_(std::move(stream)),
   ws_app_(boost::asio::make_strand(ioc_)),
   host_{},
-  port_{}
+  port_{},
+  subprotocol_{},
+  relative_target_{}
  {
   // Parse websocket address host:port :
 
-  auto pos{websocket_address.find_last_of(':')};
+  auto colon_pos{websocket_address.find_last_of(':')};
 
-  if (pos == std::string::npos)
+  if (colon_pos == std::string::npos) {
+   std::cerr << "Warning: Bad websocket address (colon missing): " << websocket_address << std::endl;
    return;
+  }
+  
+  auto slash_pos{websocket_address.find('/')};
+  if (slash_pos == std::string::npos) {
+   std::cerr << "Warning: Bad websocket address (slash missing): " << websocket_address << std::endl;
+   return;
+  }
+  if (slash_pos <= colon_pos) {
+   std::cerr << "Warning: Bad websocket address: " << websocket_address << std::endl;
+   return;
+  }
 
-  host_ = websocket_address.substr(0, pos);
-  port_ = websocket_address.substr(pos + 1);
+  host_ = websocket_address.substr(0, colon_pos);
+  port_ = websocket_address.substr(colon_pos + 1, slash_pos - (colon_pos + 1));
+  relative_target_ = websocket_address.substr(slash_pos);
  }
 
  //
@@ -89,6 +106,9 @@ public:
               std::string{"Reichwein.IT Webserver"});
       }));
 
+  // Forward subprotocol from request to target websocket
+  subprotocol_ = std::string{req[http::field::sec_websocket_protocol]};
+
   // Accept the websocket handshake
   ws_in_.async_accept(
       req,
@@ -135,8 +155,14 @@ private:
    {
     req.set(boost::beast::http::field::user_agent, "Reichwein.IT Webserver Websocket client");
    }));
+ 
+  ws_app_.set_option(boost::beast::websocket::stream_base::decorator(
+   [this](boost::beast::websocket::request_type& req)
+   {
+    req.set(boost::beast::http::field::sec_websocket_protocol, subprotocol_);
+   }));
 
-  ws_app_.async_handshake(host_, "/",
+  ws_app_.async_handshake(host_, relative_target_,
                           beast::bind_front_handler(&websocket_session::on_handshake_app, shared_from_this()));
  }
 
-- 
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