net/http 不适用于 ipv6 地址

Question

I'm trying to make a "GET" request to a local ipv6 address (discovered via mdns). The issue is that the request fails . Why is that?

package main

import (
    "fmt"
    "net/http"
)

func main() {
    url := "http://[fe80::cf5:b02f:27c3:2abe]:7070/kw/"
    rsp, err := http.Get(url)
    fmt.Println(rsp, err)
}

Output

<nil> Get http://[fe80::cf5:b02f:27c3:2abe]:7070/kw/: dial tcp [fe80::cf5:b02f:27c3:2abe]:7070: socket: Unknown protocol

Answer 1

You're trying to connect to an IPv6 link-local address, but these require a scope ID to be valid. The scope ID is usually the interface name or number (eg enp4s0 or wlp5s0 on Linux; 3 or 12 on Windows).

The % also needs to be escaped, because it appears in a URL. So it will appear as %25 .

So your URL should appear as:

url := "http://[fe80::cf5:b02f:27c3:2abe%25interface]:7070/kw/"

Where interface is your scope ID.

---

Also note well that while net/http will happily make HTTP requests to IPv6 link-local address literals, web browsers will not. They will, however, connect to names which resolve to properly scoped link-local addresses. They will also connect to global (and ULA) IPv6 address literals. If you will eventually have a web browser involved in your project, keep this in mind.