Feature-detect "use regular streams as an underlying socket for tls.connect()"

Hi, I'm looking for a good solution to be able to detect if this feature exists in the runtime my module is running on so I can throw if it's not supported. It was suggested on IRC to make an issue here.

I originally thought perhaps if I just construct a duplex stream and pass it into tls.connect, but it doesn't seem to throw an error on pre-1.4.1 versions. Suggestions?

// This doesn't seem to work
var supportswrappedjsstreams = (function(){
  var s = require("stream").Duplex();s._read=s._write=function(){};
  try { require("tls").connect({ stream: s }); return true; } catch { return false; }
});

// This does work, but not sure if this is going to suddenly break in the future
var supportswrappedjsstreams = (function(){
  try { require("_stream_wrap"); return true; } catch { return false; }
});

@indutny

@indutny

Not sure about the state it leaves the SSL context in, but something like:

var supportswrappedjsstreams = (function(){
  var s = require("stream").Duplex(); s._read = s._write = Function();
  require('tls').connect({socket: s});
  return require('events').listenerCount('error', s) > 0;
});

should work since TLS/streamwrap will always have to install error handlers.

Ah, yes, that does seem to work, even to weed out Node.js stuff. Thanks!

Oops, I may have closed that too early, because I only tested the pre-1.4.1 versions; it actually seems to have 0 listeners, even on 1.4.1:

$ iojs -pe 's=require("stream").Duplex();s._read=s._write=function(){};require("tls").connect({socket:s});require("events").EventEmitter.listenerCount("error",s)'
0

$ iojs -v
v1.4.1

Ah, whoops: it should be EE.listenerCount(emitter, "eventName");. My bad!

Interesting question! Why not just check the process.version? :)

Checking process.version is to user-agent sniffing as feature testing is to, uhm, feature testing. Inferring behavior from a version number seems brittle IMHO.

@mathiasbynens

@mathiasbynens the proposed check is much more brittle than version checking. We have semver, so this thing can't go away until 2.0.0 for sure.

@dougwilson

@dougwilson I think the check works now – ok to close?

The only working check that was provided here was to sniff the version and at the same time, I'm told in this thread not to sniff the version. I need clarification still: should I start version sniffing io.js features or can someone come up with a non-version-sniffing solution to this?

@dougwilson

@dougwilson Did you see my message about the order of EE.listenerCount params?

Oops, I missed it's specifics. Let me test that real quick. I'll either close this or provide an update today.

@chrisdickinson

@chrisdickinson I'm very sorry for the delay. This does not seem to work:

$ node -pe 's=require("stream").Duplex();s._read=s._write=function(){};require("tls").connect({socket:s});require("events").EventEmitter.listenerCount("error",s)'
2

$ node -v
v0.10.33

$ iojs -pe 's=require("stream").Duplex();s._read=s._write=function(){};require("tls").connect({socket:s});require("events").EventEmitter.listenerCount("error",s)'
1

$ iojs -v
v.1.4.1

$ iojs -pe 's=require("stream").Duplex();s._read=s._write=function(){};require("tls").connect({socket:s});require("events").EventEmitter.listenerCount("error",s)'
0

$ iojs -v
v.1.0.4

The value seems to be different in various versions and doing the > 0 seems to create false positives.

@dougwilson

I don't see an issue with version sniffing as long as you are conservative with major versions. Semver is for machines.

@dougwilson would you like to keep this open?

No, we can close it, because I just ended up ignoring io.js the entire time until the merge, so never ended up taking advantage of the feature since npm never let me do version detection against io.js.

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Feature-detect "use regular streams as an underlying socket for tls.connect()" #981

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Feature-detect "use regular streams as an underlying socket for tls.connect()" #981

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tellnes commented on Feb 27, 2015

chrisdickinson commented on Feb 27, 2015

dougwilson commented on Feb 27, 2015

dougwilson commented on Feb 27, 2015

chrisdickinson commented on Feb 27, 2015

indutny commented on Feb 27, 2015

mathiasbynens commented on Feb 27, 2015

indutny commented on Feb 27, 2015

chrisdickinson commented on Mar 12, 2015

dougwilson commented on Mar 12, 2015

chrisdickinson commented on Mar 12, 2015

dougwilson commented on Mar 12, 2015

dougwilson commented on Mar 14, 2015

brendanashworth commented on Sep 24, 2015

dougwilson commented on Sep 24, 2015

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