From 87224d2bb650812c2055ace24fee9df82259c7f8 Mon Sep 17 00:00:00 2001
From: Cory McWilliams <cory@unprompted.com>
Date: Tue, 26 Apr 2022 23:05:02 +0000
Subject: [PATCH] Add some protection against bad requests.  Also bail if we
 can't start properly.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@3870 ed5197a5-7fde-0310-b194-c3ffbd925b24
---
 core/core.js  |  2 ++
 core/httpd.js | 79 ++++++++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 71 insertions(+), 10 deletions(-)

diff --git a/core/core.js b/core/core.js
index cee3790b..537eb50e 100644
--- a/core/core.js
+++ b/core/core.js
@@ -603,6 +603,8 @@ loadSettings().then(function() {
 	httpd.registerSocketHandler("/app/socket", app.socket);
 }).catch(function(error) {
 	print('Failed to load settings.');
+	print(error);
+	exit(1);
 });
 
 exports.getSessionProcessBlob = getSessionProcessBlob;
diff --git a/core/httpd.js b/core/httpd.js
index 111529c2..210c1b2a 100644
--- a/core/httpd.js
+++ b/core/httpd.js
@@ -2,9 +2,13 @@
 
 var gHandlers = [];
 var gSocketHandlers = [];
+var gBadRequests = {};
 
 function logError(error) {
 	print("ERROR " + error);
+	if (error.stackTrace) {
+		print(error.stackTrace);
+	}
 }
 
 function addHandler(handler) {
@@ -48,7 +52,7 @@ function Request(method, uri, version, headers, body, client) {
 		this.uri = uri;
 		this.query = undefined;
 	}
-	this.version = version;
+	this.version = version || '';
 	this.headers = headers;
 	this.client = {peerName: client.peerName, tls: client.tls};
 	this.body = body;
@@ -127,7 +131,7 @@ function Response(request, client) {
 			}
 			headerString += "\r\n";
 			_started = true;
-			client.write(headerString);
+			client.write(headerString).catch(function() {});
 		},
 		end: function(data) {
 			if (_finished) {
@@ -135,25 +139,24 @@ function Response(request, client) {
 			}
 			if (data) {
 				if (_chunked) {
-					client.write(data.length.toString(16) + "\r\n" + data + "\r\n" + "0\r\n\r\n");
+					client.write(data.length.toString(16) + "\r\n" + data + "\r\n" + "0\r\n\r\n").catch(function() {});
 				} else {
-					client.write(data);
+					client.write(data).catch(function() {});
 				}
 			} else if (_chunked) {
-				client.write("0\r\n\r\n");
+				client.write("0\r\n\r\n").catch(function() {});
 			}
 			_finished = true;
 			if (!_keepAlive) {
-				client.shutdown();
+				client.shutdown().catch(function() {});
 			}
 		},
 		reportError: function(error) {
 			if (!_started) {
-				client.write("HTTP/1.1 500 Internal Server Error\r\nContent-Type: text/plain; charset=utf-8\r\n\r\n");
+				client.write("HTTP/1.1 500 Internal Server Error\r\nContent-Type: text/plain; charset=utf-8\r\n\r\n").catch(function() {});
 			}
 			if (!_finished) {
-				client.write("500 Internal Server Error\r\n\r\n" + error.stackTrace);
-				client.shutdown();
+				client.write("500 Internal Server Error\r\n\r\n" + error?.stackTrace).catch(function() {});
 			}
 			logError(client.peerName + " - - [" + new Date() + "] " + error);
 		},
@@ -175,7 +178,6 @@ function handleRequest(request, response) {
 				});
 			}
 		} catch (error) {
-			print(error);
 			response.reportError(error);
 		}
 	} else {
@@ -344,7 +346,46 @@ function webSocketAcceptResponse(key) {
 	return binary;
 }
 
+function badRequest(client, reason) {
+	var now = new Date();
+	var count = 0;
+	var old = gBadRequests[client.peerName];
+	if (!old) {
+		gBadRequests[client.peerName] = {
+			expire: new Date(now.getTime() + 10 * 60 * 1000),
+			count: 1,
+		};
+		count = 1;
+	} else {
+		old.count++;
+		count = old.count;
+	}
+	new Response({version: '1.0'}, client).reportError(reason + ': ' + count);
+	client.close();
+}
+
+function allowRequest(client) {
+	var old = gBadRequests[client.peerName];
+	if (old) {
+		var now = new Date();
+		if (old.expire < now) {
+			delete gBadRequests[client.peerName];
+			return true;
+		} else {
+			return old.count < 3;
+		}
+	} else {
+		return true;
+	}
+}
+
 function handleConnection(client) {
+	if (!allowRequest(client)) {
+		print('Rejecting client for too many bad requests: ', client.peerName);
+		client.close();
+		return;
+	}
+
 	var inputBuffer = new Uint8Array(0);
 	var request;
 	var headers = {};
@@ -378,7 +419,16 @@ function handleConnection(client) {
 		if (bodyToRead == -1) {
 			line = utf8Decode(line);
 			if (!request) {
+				if (!line) {
+					badRequest(client, 'Empty request.');
+					return false;
+				}
 				request = line.split(' ');
+				if (request.length != 3 || !request[2].startsWith('HTTP/1.')) {
+					badRequest(client, 'Bad request.');
+					request = null;
+					return false;
+				}
 				return true;
 			} else if (line) {
 				var colon = line.indexOf(':');
@@ -390,6 +440,10 @@ function handleConnection(client) {
 				if (headers["content-length"] != undefined) {
 					bodyToRead = parseInt(headers["content-length"]);
 					lineByLine = false;
+					if (bodyToRead > 16 * 1024 * 1024) {
+						badRequest(client, 'Reuqest too large: ' + bodyToRead + '.');
+						return false;
+					}
 					body = new Uint8Array(bodyToRead);
 					return true;
 				} else if (headers["connection"]
@@ -426,6 +480,7 @@ function handleConnection(client) {
 
 	client.read(function(data) {
 		if (data) {
+			const kMaxLineLength = 4096;
 			var newBuffer = new Uint8Array(inputBuffer.length + data.length);
 			newBuffer.set(inputBuffer, 0);
 			newBuffer.set(data, inputBuffer.length);
@@ -443,6 +498,10 @@ function handleConnection(client) {
 					if (end > 0 && inputBuffer[end - 1] == carriageReturn) {
 						--end;
 					}
+					if (end > kMaxLineLength || end == -1 && inputBuffer.length > kMaxLineLength) {
+						badRequest(client, 'Request too long.');
+						return;
+					}
 					if (end != -1) {
 						var line = inputBuffer.slice(0, end);
 						inputBuffer = inputBuffer.slice(realEnd + 1);