From 8a4dccc4ce91e26ddeda7fcb1409cdd251b17779 Mon Sep 17 00:00:00 2001
From: GagaPete <gagapeterbs@gmail.com>
Date: Wed, 4 Jul 2018 01:18:26 +0200
Subject: [PATCH] Fix CORS problems due to added headers on JS target

Before this change, missing User-Agent and Accept headers were automatically
added on all platforms. Setting the User-Agent header forces the browser to
do a CORS preflight (see 1) which fails if the HTTP endpoint is not
configured appropriate. It's not neccesary to set either header as the
browser sets them and so this commit disables that functionality on the JS
target.

1: https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#Simple_requests
---
 core/io/http_client.cpp     | 33 +++++++++++++++++++++++++++++++--
 scene/main/http_request.cpp | 20 --------------------
 2 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/core/io/http_client.cpp b/core/io/http_client.cpp
index 8d85e78226f..fcbb22b5deb 100644
--- a/core/io/http_client.cpp
+++ b/core/io/http_client.cpp
@@ -30,6 +30,7 @@
 
 #include "http_client.h"
 #include "io/stream_peer_ssl.h"
+#include "version.h"
 
 const char *HTTPClient::_methods[METHOD_MAX] = {
 	"GET",
@@ -121,16 +122,30 @@ Error HTTPClient::request_raw(Method p_method, const String &p_url, const Vector
 		request += "Host: " + conn_host + ":" + itos(conn_port) + "\r\n";
 	}
 	bool add_clen = p_body.size() > 0;
+	bool add_uagent = true;
+	bool add_accept = true;
 	for (int i = 0; i < p_headers.size(); i++) {
 		request += p_headers[i] + "\r\n";
-		if (add_clen && p_headers[i].find("Content-Length:") == 0) {
+		if (add_clen && p_headers[i].findn("Content-Length:") == 0) {
 			add_clen = false;
 		}
+		if (add_uagent && p_headers[i].findn("User-Agent:") == 0) {
+			add_uagent = false;
+		}
+		if (add_accept && p_headers[i].findn("Accept:") == 0) {
+			add_accept = false;
+		}
 	}
 	if (add_clen) {
 		request += "Content-Length: " + itos(p_body.size()) + "\r\n";
 		// Should it add utf8 encoding?
 	}
+	if (add_uagent) {
+		request += "User-Agent: GodotEngine/" + String(VERSION_FULL_BUILD) + " (" + OS::get_singleton()->get_name() + ")\r\n";
+	}
+	if (add_accept) {
+		request += "Accept: */*\r\n";
+	}
 	request += "\r\n";
 	CharString cs = request.utf8();
 
@@ -173,17 +188,31 @@ Error HTTPClient::request(Method p_method, const String &p_url, const Vector<Str
 	} else {
 		request += "Host: " + conn_host + ":" + itos(conn_port) + "\r\n";
 	}
+	bool add_uagent = true;
+	bool add_accept = true;
 	bool add_clen = p_body.length() > 0;
 	for (int i = 0; i < p_headers.size(); i++) {
 		request += p_headers[i] + "\r\n";
-		if (add_clen && p_headers[i].find("Content-Length:") == 0) {
+		if (add_clen && p_headers[i].findn("Content-Length:") == 0) {
 			add_clen = false;
 		}
+		if (add_uagent && p_headers[i].findn("User-Agent:") == 0) {
+			add_uagent = false;
+		}
+		if (add_accept && p_headers[i].findn("Accept:") == 0) {
+			add_accept = false;
+		}
 	}
 	if (add_clen) {
 		request += "Content-Length: " + itos(p_body.utf8().length()) + "\r\n";
 		// Should it add utf8 encoding?
 	}
+	if (add_uagent) {
+		request += "User-Agent: GodotEngine/" + String(VERSION_FULL_BUILD) + " (" + OS::get_singleton()->get_name() + ")\r\n";
+	}
+	if (add_accept) {
+		request += "Accept: */*\r\n";
+	}
 	request += "\r\n";
 	request += p_body;
 
diff --git a/scene/main/http_request.cpp b/scene/main/http_request.cpp
index ae21775c55d..4750e056333 100644
--- a/scene/main/http_request.cpp
+++ b/scene/main/http_request.cpp
@@ -30,8 +30,6 @@
 
 #include "http_request.h"
 
-#include "version.h"
-
 void HTTPRequest::_redirect_request(const String &p_new_url) {
 }
 
@@ -106,28 +104,10 @@ Error HTTPRequest::request(const String &p_url, const Vector<String> &p_custom_h
 
 	validate_ssl = p_ssl_validate_domain;
 
-	bool has_user_agent = false;
-	bool has_accept = false;
 	headers = p_custom_headers;
 
 	request_data = p_request_data;
 
-	for (int i = 0; i < headers.size(); i++) {
-
-		if (headers[i].findn("user-agent:") == 0)
-			has_user_agent = true;
-		if (headers[i].findn("Accept:") == 0)
-			has_accept = true;
-	}
-
-	if (!has_user_agent) {
-		headers.push_back("User-Agent: GodotEngine/" + String(VERSION_FULL_BUILD) + " (" + OS::get_singleton()->get_name() + ")");
-	}
-
-	if (!has_accept) {
-		headers.push_back("Accept: */*");
-	}
-
 	requesting = true;
 
 	if (use_threads) {