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net.server_epoll: Call :shutdown() on TLS sockets when supported Comment from Matthew: This fixes a potential issue where the Prosody process gets blocked on sockets waiting for them to close. Unlike non-TLS sockets, closing a TLS socket sends layer 7 data, and this can cause problems for sockets which are in the process of being cleaned up. This depends on LuaSec changes which are not yet upstream. From Martijn's original email: So first my analysis of luasec. in ssl.c the socket is put into blocking mode right before calling SSL_shutdown() inside meth_destroy(). My best guess to why this is is because meth_destroy is linked to the __close and __gc methods, which can't exactly be called multiple times and luasec does want to make sure that a tls session is shutdown as clean as possible. I can't say I disagree with this reasoning and don't want to change this behaviour. My solution to this without changing the current behaviour is to introduce a shutdown() method. I am aware that this overlaps in a conflicting way with tcp's shutdown method, but it stays close to the OpenSSL name. This method calls SSL_shutdown() in the current (non)blocking mode of the underlying socket and returns a boolean whether or not the shutdown is completed (matching SSL_shutdown()'s 0 or 1 return values), and returns the familiar ssl_ioerror() strings on error with a false for completion. This error can then be used to determine if we have wantread/wantwrite to finalize things. Once meth_shutdown() has been called once a shutdown flag will be set, which indicates to meth_destroy() that the SSL_shutdown() has been handled by the application and it shouldn't be needed to set the socket to blocking mode. I've left the SSL_shutdown() call in the LSEC_STATE_CONNECTED to prevent TOCTOU if the application reaches a timeout for the shutdown code, which might allow SSL_shutdown() to clean up anyway at the last possible moment. Another thing I've changed to luasec is the call to socket_setblocking() right before calling close(2) in socket_destroy() in usocket.c. According to the latest POSIX[0]: Note that the requirement for close() on a socket to block for up to the current linger interval is not conditional on the O_NONBLOCK setting. Which I read to mean that removing O_NONBLOCK on the socket before close doesn't impact the behaviour and only causes noise in system call tracers. I didn't touch the windows bits of this, since I don't do windows. For the prosody side of things I've made the TLS shutdown bits resemble interface:onwritable(), and put it under a combined guard of self._tls and self.conn.shutdown. The self._tls bit is there to prevent getting stuck on this condition, and self.conn.shutdown is there to prevent the code being called by instances where the patched luasec isn't deployed. The destroy() method can be called from various places and is read by me as the "we give up" error path. To accommodate for these unexpected entrypoints I've added a single call to self.conn:shutdown() to prevent the socket being put into blocking mode. I have no expectations that there is any other use here. Same as previous, the self.conn.shutdown check is there to make sure it's not called on unpatched luasec deployments and self._tls is there to make sure we don't call shutdown() on tcp sockets. I wouldn't recommend logging of the conn:shutdown() error inside close(), since a lot of clients simply close the connection before SSL_shutdown() is done.

local hex = require "util.hex";

local function parse(pkt_desc)
	local result = {};
	for line in pkt_desc:gmatch("([^\n]+)\n") do
		local b1, b2, b3, b4 = line:match("^%s*(%x%x) (%x%x) (%x%x) (%x%x)%s");
		if b1 then
			table.insert(result, b1);
			table.insert(result, b2);
			table.insert(result, b3);
			table.insert(result, b4);
		end
	end
	return hex.decode(table.concat(result));
end

local sample_packet = parse[[
      00 01 00 60     Request type and message length
      21 12 a4 42     Magic cookie
      78 ad 34 33  }
      c6 ad 72 c0  }  Transaction ID
      29 da 41 2e  }
      00 06 00 12     USERNAME attribute header
      e3 83 9e e3  }
      83 88 e3 83  }
      aa e3 83 83  }  Username value (18 bytes) and padding (2 bytes)
      e3 82 af e3  }
      82 b9 00 00  }
      00 15 00 1c     NONCE attribute header
      66 2f 2f 34  }
      39 39 6b 39  }
      35 34 64 36  }
      4f 4c 33 34  }  Nonce value
      6f 4c 39 46  }
      53 54 76 79  }
      36 34 73 41  }
      00 14 00 0b     REALM attribute header
      65 78 61 6d  }
      70 6c 65 2e  }  Realm value (11 bytes) and padding (1 byte)
      6f 72 67 00  }
      00 08 00 14     MESSAGE-INTEGRITY attribute header
      f6 70 24 65  }
      6d d6 4a 3e  }
      02 b8 e0 71  }  HMAC-SHA1 fingerprint
      2e 85 c9 a2  }
      8c a8 96 66  }
]];

describe("net.stun", function ()
	local stun = require "net.stun";

	it("works", function ()
		local packet = stun.new_packet();
		assert.is_string(packet:serialize());
	end);

	it("can decode the sample packet", function ()
		local packet = stun.new_packet():deserialize(sample_packet);
		assert(packet);
		local method, method_name = packet:get_method();
		assert.equal(1, method);
		assert.equal("binding", method_name);
		assert.equal("example.org", packet:get_attribute("realm"));
	end);

	it("can generate the sample packet", function ()
		-- These values, and the sample packet, come from RFC 5769 2.4
		local username = string.char(
			-- U+30DE KATAKANA LETTER MA
			0xE3, 0x83, 0x9E,
			-- U+30C8 KATAKANA LETTER TO
			0xE3, 0x83, 0x88,
			-- U+30EA KATAKANA LETTER RI
			0xE3, 0x83, 0xAA,
			-- U+30C3 KATAKANA LETTER SMALL TU
			0xE3, 0x83, 0x83,
			-- U+30AF KATAKANA LETTER KU
			0xE3, 0x82, 0xAF,
			-- U+30B9 KATAKANA LETTER SU
			0xE3, 0x82, 0xB9
		);

		--    Password:  "The<U+00AD>M<U+00AA>tr<U+2168>" and "TheMatrIX" (without
		--       quotes) respectively before and after SASLprep processing
		local password = "TheMatrIX";
		local realm = "example.org";

		local p3 = stun.new_packet("binding", "request");
		p3.transaction_id = hex.decode("78AD3433C6AD72C029DA412E");
		p3:add_attribute("username", username);
		p3:add_attribute("nonce", "f//499k954d6OL34oL9FSTvy64sA");
		p3:add_attribute("realm", realm);
		local key = stun.get_long_term_auth_key(realm, username, password);
		p3:add_message_integrity(key);
		assert.equal(sample_packet, p3:serialize());
	end);
end);