如何使用net/http在服务器中获取服务器自己的地址？

Question

我想使用Go的net/HTTP包编写一个HTTP服务器，其反应将取决于HTTP连接的服务器端IP地址。

换句话说，我正在寻找的是相当于CGI的"SERVER_ADDR"变量。

http中最近的字段。请求是"主机"，但由于只有当请求使用文字地址时，它才会等于地址，所以我不能使用它（服务器可能按名称使用）。

查看以下来源https://golang.org/src/net/http/server.go，似乎获取服务器地址的唯一方法是Hijack（）处理程序中的连接，并对同一连接上的后续请求执行后续HTTP解析，但至少可以说，这看起来非常不雅。。。

看起来理想的解决方案是将golang标准库中的http/request和http/server修改如下：

diff -u go-stock-library/request.go ./request.go
--- go-stock-library/request.go 2016-04-13 17:31:48.000000000 +0200
+++ ./request.go    2016-04-13 17:32:40.000000000 +0200
@@ -227,6 +227,15 @@
    // This field is ignored by the HTTP client.
    RemoteAddr string
+   // LocalAddr allows HTTP servers and other software to record
+   // the network address that the request was sent to, usually for
+   // logging. This field is not filled in by ReadRequest and
+   // has no defined format. The HTTP server in this package
+   // sets LocalAddr to an "IP:port" address before invoking a
+   // handler.
+   // This field is ignored by the HTTP client.
+   LocalAddr string
+
    // RequestURI is the unmodified Request-URI of the
    // Request-Line (RFC 2616, Section 5.1) as sent by the client
    // to a server. Usually the URL field should be used instead.
diff -u go-stock-library/server.go ./server.go
--- go-stock-library/server.go  2016-04-13 17:29:19.000000000 +0200
+++ ./server.go 2016-04-13 17:31:38.000000000 +0200
@@ -161,6 +161,13 @@
    // This is the value of a Handler's (*Request).RemoteAddr.
    remoteAddr string
+   // serverAddr is rwc.LocalAddr().String(). It is not populated synchronously
+   // inside the Listener's Accept goroutine, as some implementations block.
+   // It is populated immediately inside the (*conn).serve goroutine.
+   // This is the value of a Handler's (*Request).LocalAddr.
+   localAddr string
+   
+
    // tlsState is the TLS connection state when using TLS.
    // nil means not TLS.
    tlsState *tls.ConnectionState
@@ -736,6 +743,7 @@
    delete(req.Header, "Host")
    req.RemoteAddr = c.remoteAddr
+   req.LocalAddr = c.localAddr
    req.TLS = c.tlsState
    if body, ok := req.Body.(*body); ok {
        body.doEarlyClose = true
@@ -1382,6 +1390,7 @@
 // Serve a new connection.
 func (c *conn) serve() {
    c.remoteAddr = c.rwc.RemoteAddr().String()
+   c.localAddr = c.rwc.LocalAddr().String()
    defer func() {
        if err := recover(); err != nil {
            const size = 64 << 10

然后在代码中使用新的LocalAddr。

有更干净的方法吗？

Answer 1

我个人不会为了其他方式而修改标准库中的任何内容。从每个连接中解析它有什么好处吗？

可能有一种更简单的方法，但我有以下方法。

func getMyInterfaceAddr() (net.IP, error) {

    ifaces, err := net.Interfaces()
    if err != nil {
        return nil, err
    }
    addresses := []net.IP{}
    for _, iface := range ifaces {
        if iface.Flags&net.FlagUp == 0 {
            continue // interface down
        }
        if iface.Flags&net.FlagLoopback != 0 {
            continue // loopback interface
        }
        addrs, err := iface.Addrs()
        if err != nil {
            continue
        }
        for _, addr := range addrs {
            var ip net.IP
            switch v := addr.(type) {
            case *net.IPNet:
                ip = v.IP
            case *net.IPAddr:
                ip = v.IP
            }
            if ip == nil || ip.IsLoopback() {
                continue
            }
            ip = ip.To4()
            if ip == nil {
                continue // not an ipv4 address
            }
            addresses = append(addresses, ip)
        }
    }
    if len(addresses) == 0 {
        return nil, fmt.Errorf("no address Found, net.InterfaceAddrs: %v", addresses)
    }
    //only need first
    return addresses[0], nil
}