Implement localAddress in Agent

[mcollina]

Originally posted by @RemoQuality in https://github.com/nodejs/undici/discussions/1577:

I was trying to use undici request with option to select which IP address should be used to request but without any success.

Example how I am doing it with AXIOS: await axios(url, { httpsAgent: new https.Agent({ localAddress: "XXX.XXX.XXX.XXX", keepAlive: true, keepAliveMsecs: 30000 }) }) .then(res => {}) any possibilities of that with undici?

[mcollina]

This will be a good feature to add!

[sidwebworks]

@mcollina I would love to work on this, any suggestions as to where I should start looking to implement this?

My guess is, inside agent.js the Agent expects a factory that either returns a Client or a Pool https://github.com/nodejs/undici/blob/main/lib/agent.js#L49

And inside the client.js this is where the IP resolution happens i guess? https://github.com/nodejs/undici/blob/03cfc4be563e19fb55ec33177dcf45c45fee828c/lib/client.js#L997

Or am I just digging the wrong part of the codebase :smile:

[mcollina]

I think this should be in client.js.

[metcoder95]

Can be closed with #1659?