How Can I Specify a Custom Source IP Address for HTTP Requests in Go?

Customizing IP Selection for HTTP Requests

The standard library for HTTP requests in Go does not explicitly specify the source IP address used for outgoing requests. This raises the question: can we manually specify the IP address for such requests?

Solution

Yes, we can set a custom Dialer in the Client's Transport to control the IP address used for HTTP requests. Here's how:

// Create a transport like http.DefaultTransport, but with a specified localAddr
transport := &http.Transport{
    Proxy: http.ProxyFromEnvironment,
    DialContext: (&net.Dialer{
        Timeout:   30 * time.Second,
        KeepAlive: 30 * time.Second,
        LocalAddr: localAddr, // Set the desired local address here
        DualStack: true,
    }).DialContext,
    MaxIdleConns:          100,
    IdleConnTimeout:       90 * time.Second,
    TLSHandshakeTimeout:   10 * time.Second,
    ExpectContinueTimeout: 1 * time.Second,
}

// Create an HTTP client with the custom transport
client := &http.Client{
    Transport: transport,
}

By assigning a LocalAddr to the Dialer, you can specify the source IP address that will be used for HTTP requests made through that client. This allows you to control the IP address that will be exposed to the destination server, providing flexibility in managing IP reputation or routing considerations.

The above is the detailed content of How Can I Specify a Custom Source IP Address for HTTP Requests in Go?. For more information, please follow other related articles on the PHP Chinese website!