From c5aa9789124ebd50f96fb6335359cfa9f0d64b00 Mon Sep 17 00:00:00 2001
From: Michael Friedrich <michael.friedrich@icinga.com>
Date: Fri, 6 Sep 2019 14:19:53 +0200
Subject: [PATCH] Rewrite error handling in
 HttpServerConnection#EnsureValidHeaders()

Throwing local exceptions unnecessarily pollutes the exception
stack with immediate unwinding. Avoid this pattern at all cost within
Boost.Coroutines. MSVC may handle exceptions differently and cause
problems with stack unwinding.

refs #7431
refs #7351
---
 lib/remote/httpserverconnection.cpp | 42 +++++++++++++----------------
 1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/lib/remote/httpserverconnection.cpp b/lib/remote/httpserverconnection.cpp
index 01b32f403..cca0ff799 100644
--- a/lib/remote/httpserverconnection.cpp
+++ b/lib/remote/httpserverconnection.cpp
@@ -146,43 +146,37 @@ bool EnsureValidHeaders(
 {
 	namespace http = boost::beast::http;
 
-	bool httpError = true;
+	bool httpError = false;
+	String errorMsg;
 
-	try {
-		boost::system::error_code ec;
+	boost::system::error_code ec;
 
-		http::async_read_header(stream, buf, parser, yc[ec]);
+	http::async_read_header(stream, buf, parser, yc[ec]);
 
-		if (ec) {
-			/**
-			 * Unfortunately there's no way to tell an HTTP protocol error
-			 * from an error on a lower layer:
-			 *
-			 * <https://github.com/boostorg/beast/issues/643>
-			 */
-			throw std::invalid_argument(ec.message());
-		}
+	if (ec) {
+		errorMsg = ec.message();
+		httpError = true;
+	}
 
-		httpError = false;
+	switch (parser.get().version()) {
+	case 10:
+	case 11:
+		break;
+	default:
+		errorMsg = "Unsupported HTTP version";
+	}
 
-		switch (parser.get().version()) {
-		case 10:
-		case 11:
-			break;
-		default:
-			throw std::invalid_argument("Unsupported HTTP version");
-		}
-	} catch (const std::invalid_argument& ex) {
+	if (!errorMsg.IsEmpty() || httpError) {
 		response.result(http::status::bad_request);
 
 		if (!httpError && parser.get()[http::field::accept] == "application/json") {
 			HttpUtility::SendJsonBody(response, nullptr, new Dictionary({
 				{ "error", 400 },
-				{ "status", String("Bad Request: ") + ex.what() }
+				{ "status", String("Bad Request: ") + errorMsg }
 			}));
 		} else {
 			response.set(http::field::content_type, "text/html");
-			response.body() = String("<h1>Bad Request</h1><p><pre>") + ex.what() + "</pre></p>";
+			response.body() = String("<h1>Bad Request</h1><p><pre>") + errorMsg + "</pre></p>";
 			response.set(http::field::content_length, response.body().size());
 		}