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-rw-r--r--net/websocket/frames.lua22
-rw-r--r--plugins/mod_websocket.lua182
2 files changed, 119 insertions, 85 deletions
diff --git a/net/websocket/frames.lua b/net/websocket/frames.lua
index 5e17df07..a0f3bd89 100644
--- a/net/websocket/frames.lua
+++ b/net/websocket/frames.lua
@@ -18,9 +18,7 @@ local rshift = bit.rshift;
local unpack = table.unpack or unpack; -- luacheck: ignore 113
local t_concat = table.concat;
-local s_byte = string.byte;
local s_char= string.char;
-local s_sub = string.sub;
local s_pack = string.pack;
local s_unpack = string.unpack;
@@ -30,12 +28,12 @@ if not s_pack and softreq"struct" then
end
local function read_uint16be(str, pos)
- local l1, l2 = s_byte(str, pos, pos+1);
+ local l1, l2 = str:byte(pos, pos+1);
return l1*256 + l2;
end
-- FIXME: this may lose precision
local function read_uint64be(str, pos)
- local l1, l2, l3, l4, l5, l6, l7, l8 = s_byte(str, pos, pos+7);
+ local l1, l2, l3, l4, l5, l6, l7, l8 = str:byte(pos, pos+7);
local h = lshift(l1, 24) + lshift(l2, 16) + lshift(l3, 8) + l4;
local l = lshift(l5, 24) + lshift(l6, 16) + lshift(l7, 8) + l8;
return h * 2^32 + l;
@@ -63,9 +61,15 @@ end
if s_unpack then
function read_uint16be(str, pos)
+ if type(str) ~= "string" then
+ str, pos = str:sub(pos, pos+1), 1;
+ end
return s_unpack(">I2", str, pos);
end
function read_uint64be(str, pos)
+ if type(str) ~= "string" then
+ str, pos = str:sub(pos, pos+7), 1;
+ end
return s_unpack(">I8", str, pos);
end
end
@@ -73,7 +77,7 @@ end
local function parse_frame_header(frame)
if #frame < 2 then return; end
- local byte1, byte2 = s_byte(frame, 1, 2);
+ local byte1, byte2 = frame:byte(1, 2);
local result = {
FIN = band(byte1, 0x80) > 0;
RSV1 = band(byte1, 0x40) > 0;
@@ -102,7 +106,7 @@ local function parse_frame_header(frame)
end
if result.MASK then
- result.key = { s_byte(frame, length_bytes+3, length_bytes+6) };
+ result.key = { frame:byte(length_bytes+3, length_bytes+6) };
end
return result, header_length;
@@ -121,7 +125,7 @@ local function apply_mask(str, key, from, to)
for i = from, to do
local key_index = counter%key_len + 1;
counter = counter + 1;
- data[counter] = s_char(bxor(key[key_index], s_byte(str, i)));
+ data[counter] = s_char(bxor(key[key_index], str:byte(i)));
end
return t_concat(data);
end
@@ -136,7 +140,7 @@ end
local function parse_frame(frame)
local result, pos = parse_frame_header(frame);
- if result == nil or #frame < (pos + result.length) then return; end
+ if result == nil or #frame < (pos + result.length) then return nil, nil, result; end
result.data = parse_frame_body(frame, result, pos+1);
return result, pos + result.length;
end
@@ -189,7 +193,7 @@ local function parse_close(data)
if #data >= 2 then
code = read_uint16be(data, 1);
if #data > 2 then
- message = s_sub(data, 3);
+ message = data:sub(3);
end
end
return code, message
diff --git a/plugins/mod_websocket.lua b/plugins/mod_websocket.lua
index 1a0c0046..7a5f2d03 100644
--- a/plugins/mod_websocket.lua
+++ b/plugins/mod_websocket.lua
@@ -18,6 +18,7 @@ local contains_token = require "util.http".contains_token;
local portmanager = require "core.portmanager";
local sm_destroy_session = require"core.sessionmanager".destroy_session;
local log = module._log;
+local dbuffer = require "util.dbuffer";
local websocket_frames = require"net.websocket.frames";
local parse_frame = websocket_frames.parse;
@@ -27,6 +28,9 @@ local parse_close = websocket_frames.parse_close;
local t_concat = table.concat;
+local stanza_size_limit = module:get_option_number("c2s_stanza_size_limit", 10 * 1024 * 1024);
+local frame_buffer_limit = module:get_option_number("websocket_frame_buffer_limit", 2 * stanza_size_limit);
+local frame_fragment_limit = module:get_option_number("websocket_frame_fragment_limit", 8);
local stream_close_timeout = module:get_option_number("c2s_close_timeout", 5);
local consider_websocket_secure = module:get_option_boolean("consider_websocket_secure");
local cross_domain = module:get_option("cross_domain_websocket");
@@ -136,6 +140,64 @@ local default_get_response_body = [[<!DOCTYPE html><html><head><title>Websocket<
</body></html>]]
local websocket_get_response_body = module:get_option_string("websocket_get_response_body", default_get_response_body)
+local function validate_frame(frame, max_length)
+ local opcode, length = frame.opcode, frame.length;
+
+ if max_length and length > max_length then
+ return false, 1009, "Payload too large";
+ end
+
+ -- Error cases
+ if frame.RSV1 or frame.RSV2 or frame.RSV3 then -- Reserved bits non zero
+ return false, 1002, "Reserved bits not zero";
+ end
+
+ if opcode == 0x8 and frame.data then -- close frame
+ if length == 1 then
+ return false, 1002, "Close frame with payload, but too short for status code";
+ elseif length >= 2 then
+ local status_code = parse_close(frame.data)
+ if status_code < 1000 then
+ return false, 1002, "Closed with invalid status code";
+ elseif ((status_code > 1003 and status_code < 1007) or status_code > 1011) and status_code < 3000 then
+ return false, 1002, "Closed with reserved status code";
+ end
+ end
+ end
+
+ if opcode >= 0x8 then
+ if length > 125 then -- Control frame with too much payload
+ return false, 1002, "Payload too large";
+ end
+
+ if not frame.FIN then -- Fragmented control frame
+ return false, 1002, "Fragmented control frame";
+ end
+ end
+
+ if (opcode > 0x2 and opcode < 0x8) or (opcode > 0xA) then
+ return false, 1002, "Reserved opcode";
+ end
+
+ -- Check opcode
+ if opcode == 0x2 then -- Binary frame
+ return false, 1003, "Only text frames are supported, RFC 7395 3.2";
+ elseif opcode == 0x8 then -- Close request
+ return false, 1000, "Goodbye";
+ end
+
+ -- Other (XMPP-specific) validity checks
+ if not frame.FIN then
+ return false, 1003, "Continuation frames are not supported, RFC 7395 3.3.3";
+ end
+ if opcode == 0x01 and frame.data and frame.data:byte(1, 1) ~= 60 then
+ return false, 1007, "Invalid payload start character, RFC 7395 3.3.3";
+ end
+
+ return true;
+end
+
+
function handle_request(event)
local request, response = event.request, event.response;
local conn = response.conn;
@@ -159,90 +221,40 @@ function handle_request(event)
conn:close();
end
- local dataBuffer;
- local function handle_frame(frame)
- local opcode = frame.opcode;
- local length = frame.length;
- module:log("debug", "Websocket received frame: opcode=%0x, %i bytes", frame.opcode, #frame.data);
-
- -- Error cases
- if frame.RSV1 or frame.RSV2 or frame.RSV3 then -- Reserved bits non zero
- websocket_close(1002, "Reserved bits not zero");
- return false;
- end
-
- if opcode == 0x8 then -- close frame
- if length == 1 then
- websocket_close(1002, "Close frame with payload, but too short for status code");
- return false;
- elseif length >= 2 then
- local status_code = parse_close(frame.data)
- if status_code < 1000 then
- websocket_close(1002, "Closed with invalid status code");
- return false;
- elseif ((status_code > 1003 and status_code < 1007) or status_code > 1011) and status_code < 3000 then
- websocket_close(1002, "Closed with reserved status code");
- return false;
- end
- end
- end
-
- if opcode >= 0x8 then
- if length > 125 then -- Control frame with too much payload
- websocket_close(1002, "Payload too large");
- return false;
- end
-
- if not frame.FIN then -- Fragmented control frame
- websocket_close(1002, "Fragmented control frame");
- return false;
- end
- end
-
- if (opcode > 0x2 and opcode < 0x8) or (opcode > 0xA) then
- websocket_close(1002, "Reserved opcode");
- return false;
+ local function websocket_handle_error(session, code, message)
+ if code == 1009 then -- stanza size limit exceeded
+ -- we close the session, rather than the connection,
+ -- otherwise a resuming client will simply resend the
+ -- offending stanza
+ session:close({ condition = "policy-violation", text = "stanza too large" });
+ else
+ websocket_close(code, message);
end
+ end
- if opcode == 0x0 and not dataBuffer then
- websocket_close(1002, "Unexpected continuation frame");
- return false;
- end
+ local function handle_frame(frame)
+ module:log("debug", "Websocket received frame: opcode=%0x, %i bytes", frame.opcode, #frame.data);
- if (opcode == 0x1 or opcode == 0x2) and dataBuffer then
- websocket_close(1002, "Continuation frame expected");
- return false;
+ -- Check frame makes sense
+ local frame_ok, err_status, err_text = validate_frame(frame, stanza_size_limit);
+ if not frame_ok then
+ return frame_ok, err_status, err_text;
end
- -- Valid cases
- if opcode == 0x0 then -- Continuation frame
- dataBuffer[#dataBuffer+1] = frame.data;
- elseif opcode == 0x1 then -- Text frame
- dataBuffer = {frame.data};
- elseif opcode == 0x2 then -- Binary frame
- websocket_close(1003, "Only text frames are supported");
- return;
- elseif opcode == 0x8 then -- Close request
- websocket_close(1000, "Goodbye");
- return;
- elseif opcode == 0x9 then -- Ping frame
+ local opcode = frame.opcode;
+ if opcode == 0x9 then -- Ping frame
frame.opcode = 0xA;
frame.MASK = false; -- Clients send masked frames, servers don't, see #1484
conn:write(build_frame(frame));
return "";
elseif opcode == 0xA then -- Pong frame, MAY be sent unsolicited, eg as keepalive
return "";
- else
+ elseif opcode ~= 0x1 then -- Not text frame (which is all we support)
log("warn", "Received frame with unsupported opcode %i", opcode);
return "";
end
- if frame.FIN then
- local data = t_concat(dataBuffer, "");
- dataBuffer = nil;
- return data;
- end
- return "";
+ return frame.data;
end
conn:setlistener(c2s_listener);
@@ -260,19 +272,37 @@ function handle_request(event)
session.open_stream = session_open_stream;
session.close = session_close;
- local frameBuffer = "";
+ local frameBuffer = dbuffer.new(frame_buffer_limit, frame_fragment_limit);
add_filter(session, "bytes/in", function(data)
+ if not frameBuffer:write(data) then
+ session.log("warn", "websocket frame buffer full - terminating session");
+ session:close({ condition = "resource-constraint", text = "frame buffer exceeded" });
+ return;
+ end
+
local cache = {};
- frameBuffer = frameBuffer .. data;
- local frame, length = parse_frame(frameBuffer);
+ local frame, length, partial = parse_frame(frameBuffer);
while frame do
- frameBuffer = frameBuffer:sub(length + 1);
- local result = handle_frame(frame);
- if not result then return; end
+ frameBuffer:discard(length);
+ local result, err_status, err_text = handle_frame(frame);
+ if not result then
+ websocket_handle_error(session, err_status, err_text);
+ break;
+ end
cache[#cache+1] = filter_open_close(result);
- frame, length = parse_frame(frameBuffer);
+ frame, length, partial = parse_frame(frameBuffer);
end
+
+ if partial then
+ -- The header of the next frame is already in the buffer, run
+ -- some early validation here
+ local frame_ok, err_status, err_text = validate_frame(partial, stanza_size_limit);
+ if not frame_ok then
+ websocket_handle_error(session, err_status, err_text);
+ end
+ end
+
return t_concat(cache, "");
end);
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-03 10:31:52 +0000