http.get option localAddress not working #3625

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1. mscdex

   added

   httpIssues and PRs related to the http subsystem.Issues and PRs related to the http subsystem.

   on Nov 2, 2015
2. mscdex commented on Nov 2, 2015

   

   mscdex

   on Nov 2, 2015

   Contributor

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   IIRC routing on Linux uses the route with the lowest metric value when multiple routes match, which in this case would agree with what you're experiencing.
3. k1tzu commented on Nov 2, 2015

   

   k1tzu

   on Nov 2, 2015

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   Of cause it uses the route with the lowest metric! But that's the question!
   I need to send packets to both interfaces with nodejs.

   In C language it is a simplest question to resolve with SO_BINDTODEVICE socket option. And I thought nodejs do this also in some intellectual way like

    //convert localAddress to the Interface name
   #ifdef __linux__
        //SO_BINDTODEVICE to the interface
   #elif __APPLE__
        //IP_BOUND_IF  to the interface
   #endif

   No problemo
4. bnoordhuis commented on Nov 2, 2015

   

   bnoordhuis

   on Nov 2, 2015

   Member

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   Perhaps it's stating the obvious but the .localAddress option binds to an address, not an interface. There is no direct support for SO_BINDTODEVICE in node.js but you can jury-rig it with socat(1):

   # so-bindtodevice needs root
   $ socat TCP4:<address>:80,so-bindtodevice=<dev> EXEC:'node script.js',nofork,fdin=3,fdout=3
   

   With script.js looking something like this:

   var socket = require('net').Socket({ fd: 3, readable: true, writable: true });
   var req = require('http').get({
     createConnection: () => socket,
     headers: { Host: 'example.com' },
   }, res => res.pipe(process.stdout));

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5. k1tzu commented on Nov 2, 2015

   

   k1tzu

   on Nov 2, 2015

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   I've found another workaround that works. Using ffi and call to setsockopt. But I wish I could do that with nodejs only.

   var http = require('http'),
       net = require('net'),
       util = require('util'),
       ffi = require('ffi');
   
   var SOL_SOCKET = 1;
   var SO_BINDTODEVICE = 25;
   var current = ffi.Library(null, {
       'setsockopt': ['int', ['int', 'int', 'int', 'string', 'int']]
   });
   
   var remoteIp = "192.168.0.1";
   var ourIp = "192.168.0.182";
   var ourInterface = "eth1";
   
   function bindingAgent(options) {
       http.Agent.call(this, options);
       this.createConnection = bindingCreateConnection;
   }
   
   util.inherits(bindingAgent, http.Agent);
   
   function bindingCreateConnection(port, host, options) {
       var socket;
       socket = new net.Socket({handle: net._createServerHandle(ourIp)});
       var iface = ourInterface;
       var r = current.setsockopt(socket._handle.fd, SOL_SOCKET, SO_BINDTODEVICE, iface, 6);
       if (r === -1)
           throw new Error("getsockopt(SO_BINDTODEVICE) error");
   
       socket.connect(port, host);
   
       return socket;
   }
   
   var optionsAgent = {};
   var ourBindingAgent = new bindingAgent(optionsAgent);
   
   var httpReq = {};
   httpReq.port = 80;
   httpReq.host = remoteIp;
   httpReq.path = '/index.html';
   httpReq.headers = {'Referer': 'http://' + remoteIp + ':' + httpReq.port + '/index.html'};
   httpReq.agent = ourBindingAgent;
   
   var body = '';
   var creq = http.get(httpReq);
   creq.on('response', function (res) {
       res.setEncoding('utf8');
       res.on('data', function (chunk) {
           console.log(chunk);
       });
   });

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6. Fishrock123

   added

   questionIssues asking questions about Node.js.Issues asking questions about Node.js.

   on Nov 2, 2015
7. mscdex

   added

   feature requestIssues requesting new Node.js features.Issues requesting new Node.js features.

   on Nov 2, 2015
8. jasnell

   closed this as completedon Mar 22, 2016