Node http-proxy-simple

Abstract

This is a Node.js extension module for implementing a very simple HTTP proxy which allows you to on-the-fly intercept and modify HTTP request/response header and payload information. It is primarily intended for development scenarios where a full-featured HTTP proxy is not necessary but the data of an own application needs to be on-the-fly modified for testing and instrumentation purposes.

Installation

Use the Node Package Manager (NPM) to install this module locally (default) or globally (with option -g):

$ npm install [-g] http-proxy-simple

Usage

var proxy = require("./http-proxy-simple").createProxyServer({
    host: "0.0.0.0",
    port: 4129
});

proxy.on("connection-open", function (cid, socket) {
   console.log("proxy: " + cid + ": TCP connection open");
});

proxy.on("connection-error", function (cid, socket, error) {
   console.log("proxy: " + cid + ": TCP connection error: " + error);
});

proxy.on("connection-close", function (cid, socket, had_error) {
   console.log("proxy: " + cid + ": TCP connection close");
});

proxy.on("http-request", function (cid, request, response) {
   console.log("proxy: " + cid + ": HTTP request: " + request.url);
});

proxy.on("http-error", function (cid, error, request, response) {
   console.log("proxy: " + cid + ": HTTP error: " + error);
});

proxy.on("http-intercept-request", function (cid, request, response, remoteRequest, performRequest) {
   console.log("proxy: " + cid + ": HTTP intercept request");
   performRequest(remoteRequest);
});

proxy.on("http-intercept-response", function (cid, request, response, remoteResponse, remoteResponseBody, performResponse) {
   console.log("proxy: " + cid + ": HTTP intercept response");
   if (   remoteResponse.headers["content-type"]
       && remoteResponse.headers["content-type"].toLowerCase() === "text/html") {
       var body = remoteResponseBody.toString("utf8");
       var css = "<style>body { border: 10px solid red !important; }</style>";
       remoteResponseBody = body.replace(/(<\/head>)/i, css + "$1");
       remoteResponse.headers["content-length"] = remoteResponseBody.length;
       console.log("proxy: " + cid + ": HTTP intercept response: MODIFIED RESPONSE BODY");
   }
   performResponse(remoteResponse, remoteResponseBody);
});

Application Programming Interface (API)

Method: createProxyServer(options: Options): ProxyServer

Create a proxy server. The following options are supported:

• host: IP address (or name) for listening for HTTP proxy requests. Defaults to 127.0.0.1.
• port: TCP port for listening for HTTP proxy requests. Defaults to 3128.
• servername: server host name for identification purposes in HTTP Via headers. Defaults to the result of os.hostname().
• id: optional software name/version pair for identification purposes in HTTP Viaheaders. Defaults to http-proxy-simple/X.X.X.
• proxy: optional upstream proxy to forward requests to. Defaults to "" (no forward proxy).

The following events are emitted:

• connection-open (cid, socket)
• connection-error (cid, socket, error)
• connection-close (cid, socket, had_error)
• http-request (cid, request, response)
• http-error (cid, error, request, response)
• http-intercept-request (cid, request, response, remoteRequest, performRequest)
• http-intercept-response (cid, request, response, remoteResponse, remoteResponseBody, performResponse)

See Also

• node http.Server
• node request

Credits

Thanks to Michael C. Axiak for its FilterNet module which inspired this module. FilterNet is more feature-packed (it also provides SSL/TLS support, compression support, etc) but had too much dependencies and especially did not support proxy forwarding.

License

Copyright (c) 2013-2019 Dr. Ralf S. Engelschall (http://engelschall.com/)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.