How to capture http messages from Request Node library with Fiddler - node.js

Question

Regular client initiated requests to the node server are captured fine in Fiddler. However, requests sent from node to a web service are not captured. It did not help to pass in config for proxy (127.0.0.1:8888) to the request method. How can I route the request messages through Fiddler?
var http = require('http');
var request = require('request');
request.get(webserviceURL, { "auth" : {"user": "user", "pass" = "pass", sendImmediately: true },
"proxy" : { "host" : "127.0.0.1", "port" : 8888 }},
function (error, response) { console.log( "response received" );
});
Request repo: https://github.com/mikeal/request

Answer 1

I just tried to do this myself (using Fiddler and the request library from npm). Here's how I got it working:
process.env['NODE_TLS_REJECT_UNAUTHORIZED'] = '0'; // Ignore 'UNABLE_TO_VERIFY_LEAF_SIGNATURE' authorization error
// Issue the request
request(
{
method: "GET",
uri: "https://secure.somewebsite.com/",
proxy: "http://127.0.0.1:8888" // Note the fully-qualified path to Fiddler proxy. No "https" is required, even for https connections to outside.
},
function(err, response, body) {
console.log("done");
});
This is with Fiddler2 using the default port and proxy options (and no proxy authentication).

Answer 2

Fiddler works by setting your "Internet Options" (from start menu) "Connections" > "LAN Settings" > "Proxy Server" to its port, thus making all HTTP traffic (clients which obey this setting) go through it.
You should point your node.js client lib to use a proxy, the settings are written in that options dialog after you start Fiddler.

Answer 3

The proxy option should be a full url, like this:
proxy : "http://127.0.0.1:8888"

Answer 4

To do this on an ad-hoc basis, without changing your code, you can use environment variables.
Request respects:
HTTP_PROXY
HTTPS_PROXY
NO_PROXY
So, to proxy just set these in your console before running your process.
For example, to setup http and https proxy use:
set HTTP_PROXY="http://127.0.0.1:8888"
set HTTPS_PROXY="http://127.0.0.1:8888"
set NODE_TLS_REJECT_UNAUTHORIZED=0
The latter line stops issues with SSL through the fiddler proxy.

Answer 5

I've been wanting the same... an equivalent of the Network tab in chrome DevTools, only for Nodejs. Unfortunately, it doesn't appear as though one exists. I don't have Fiddler on macos, so this is how I went about stubbing the require('http') methods to log and pass though. Leaving this here in case I need it again or someone else finds it helpful. You can turn it on by attaching a debugger and require('filename')() the file containing this script.
module.exports = () => {
const http = require('http');
http._request = http.request;
global.DO_LOG_AJAX = true;
const log = str => {
if (global.DO_LOG_AJAX) {
console.debug(str);
}
};
const flushLog = (requestLines, responseLines) => {
if (global.DO_LOG_AJAX) {
log([
'----------------Begin Request-----------------------------------',
...requestLines,
'----------------End Request / Begin Response--------------------',
...responseLines,
'----------------End Reponse-------------------------------------',
].join('\n'));
}
};
let write;
let end;
http.request = (...requestParams) => {
const req = http._request(...requestParams);
const { method, path, headers, host, port } = requestParams[0];
const requestLogLines = [];
requestLogLines.push(`${method} ${path}`);
requestLogLines.push(`Host: ${host}:${port}`);
for (const header of Object.keys(headers)) {
requestLogLines.push(`${header}: ${headers[header]}`);
}
write = write || req.write;
end = end || req.end;
req.on('error', err => {
log({ err });
});
req._write = write;
req._end = end;
const requestBody = [];
req.write = (...writeParams) => {
requestBody.push(writeParams[0].toString());
return req._write(...writeParams);
};
req.end = (...endParams) => {
if (endParams[0]) {
requestBody.push(endParams[0].toString());
}
requestLogLines.push('');
requestLogLines.push(requestBody.join(''));
return req._end(...endParams);
};
const responseLogLines = [];
req.once('response', response => {
const responseBody = [];
responseLogLines.push(`${response.statusCode} ${response.statusMessage}`);
for (const header of Object.keys(response.headers)) {
responseLogLines.push(`${header}: ${response.headers[header]}`);
}
const onData = chunk => {
responseBody.push(chunk.toString());
};
const onClose = err => {
responseLogLines.push('');
responseLogLines.push(responseBody.join(''));
responseLogLines.push('');
responseLogLines.push(`--- ERROR --- ${err.toString()}`);
flushLog(requestLogLines, responseLogLines);
req.removeListener('data', onData);
};
const onEnd = () => {
responseLogLines.push('');
responseLogLines.push(responseBody.join(''));
flushLog(requestLogLines, responseLogLines);
req.removeListener('data', onData);
};
response.on('data', onData);
response.once('close', onClose);
response.once('end', onEnd);
});
return req;
};
};