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

1 files changed, 31 insertions, 2 deletions

diff --git a/core/io/http_client.cpp b/core/io/http_client.cpp
index 8d85e78226..fcbb22b5de 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;