Node.js ReadLine not waiting for a full line on socket connections?
Problem
I am trying to use Node.js's ReadLine with a socket, like so:
var net = require('net');
var rl = require('readline');
this.streamServer = net.createServer(function (socket) {
var i = rl.createInterface(socket, socket);
i.on('line', function (line) {
socket.write(line);
});
});
this.streamServer.maxConnections = 1;
this.streamServer.listen(7001);
When I telnet into port 7001 and start typing text, it is immediately echoed back to me before I ever push enter.
Why is ReadLine not waiting for a full line?
I have also tried .question() and I get the same results... The callback is fired upon reception of any data, without waiting for an end-of-line character.
Edit: This gets even stranger. When I test using the Windows telnet client, I get the behavior that I stated above. However, if I test using PuTTY as the client, ReadLine works, even on Windows. I did some packet captures. Maybe someone could shed some light on this? Unindented lines are data from the client. Indented lines are the server replies.
Using Windows Telnet
00000000 61 a
00000000 61 a
00000001 62 b
00000001 62 b
00000002 63 c
00000002 63 c
00000003 64 d
00000003 64 d
00000004 65 e
00000004 65 e
00000005 66 f
00000005 66 f
00000006 67 g
00000006 67 g
00000007 68 h
00000007 68 h
00000008 69 i
00000008 69 i
00000009 6a j
00000009 6a j
0000000A 6b k
0000000A 6b k
0000000B 6c l
0000000B 6c l
0000000C 6d m
0000000C 6d m
0000000D 6e n
0000000D 6e n
0000000E 6f o
0000000E 6f o
0000000F 70 p
0000000F 70 p
00000010 0d 0a ..
00000010 0d 0a ..
00000012 0d 0a ..
00000012 0d 0a ..
00000014 0d 0a ..
00000014 0d 0a ..
00000016 61 a
00000016 61 a
00000017 73 s
00000017 73 s
00000018 64 d
00000018 64 d
00000019 66 f
00000019 66 f
0000001A 0d 0a ..
0000001A 0d 0a ..
0000001C 61 a
0000001C 61 a
0000001D 73 s
0000001D 73 s
0000001E 64 d
0000001E 64 d
0000001F 66 f
0000001F 66 f
00000020 0d 0a ..
00000020 0d 0a ..
Using PuTTY
00000000 ff fb 1f ff fb 20 ff fb 18 ff fb 27 ff fd 01 ff ..... .. ...'....
00000010 fb 03 ff fd 03 .....
00000000 ef bf bd ef bf bd 1f ef bf bd ef bf bd 20 ef bf ........ ..... ..
00000010 bd ef bf bd 18 ef bf bd ef bf bd 27 ef bf bd ef ........ ...'....
00000020 bf bd 01 ef bf bd ef bf bd 03 ef bf bd ef bf bd ........ ........
00000030 03 .
00000015 61 62 63 64 65 66 67 abcdefg
0000001C 0d 0a ..
00000031 61 62 63 64 65 66 67 abcdefg
00000038 0d 0a ..
0000001E 61 73 64 66 asdf
00000022 0d 0a ..
0000003A 61 73 64 66 asdf
0000003E 0d 0a ..
00000024 61 73 64 66 asdf
00000028 0d 0a ..
00000040 61 73 64 66 asdf
00000044 0d 0a ..
0000002A 0d 0a ..
00000046 0d 0a ..
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Solution
This is a bug in node.js, ReadLine's Interface calls _normalWrite() on each 'data' event and _normaWrite has a comment that it should try to break on newlines, but currently it just calls _onLine().
Something along the lines of this should fix it for you:
i._normalWrite = function(b) {
if(b == undefined) {
return;
}
if(!this._line_buffer) {
this._line_buffer = '';
}
this._line_buffer += b.toString();
if(this._line_buffer.indexOf('\n') !=-1 ) {
var lines = this._line_buffer.split('\n');
// either '' or the unfinished portion of the next line
this._line_buffer = lines.pop();
lines.forEach(function(line) {
this._onLine(line + '\n');
}, this);
}
};
I haven't tested this, it may need to take \r into account also. Please let me know if it works for you, if so then one of us should send node a pull request with it.
Discussion
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