Add Host and X-Forwarded-X headers if there's an HTTP connection involved

mirror/header.go

@@ -0,0 +1,51 @@
+package mirror
+
+import (
+	"bufio"
+	"net"
+	"net/http"
+)
+
+// AddHeaders adds headers to the connection.
+// It takes a net.Conn and a map of headers as input.
+// It only adds headers if the connection is an HTTP connection.
+// It returns a net.Conn with the headers added.
+func AddHeaders(conn net.Conn, headers map[string]string) net.Conn {
+	// read a request from the connection
+	// if the request is an HTTP request, add the headers
+	// if the request is not an HTTP request, return the connection as is
+	req, err := http.ReadRequest(bufio.NewReader(conn))
+	if err != nil {
+		return conn
+	}
+	for key, value := range headers {
+		req.Header.Add(key, value)
+	}
+	// write the request back to the connection
+	if err := req.Write(conn); err != nil {
+		return conn
+	}
+	// return the connection with the headers added
+	return conn
+}
+
+// Accept accepts a connection from the listener.
+// It takes a net.Listener as input and returns a net.Conn with the headers added.
+// It is used to accept connections from the meta listener and add headers to them.
+func (ml *Mirror) Accept() (net.Conn, error) {
+	// Accept a connection from the listener
+	conn, err := ml.MetaListener.Accept()
+	if err != nil {
+		return nil, err
+	}
+
+	host := map[string]string{
+		"Host":              ml.MetaListener.Addr().String(),
+		"X-Forwarded-For":   conn.RemoteAddr().String(),
+		"X-Forwarded-Proto": "http",
+	}
+	// Add headers to the connection
+	conn = AddHeaders(conn, host)
+
+	return conn, nil
+}