github.com/letsencrypt/trillian@v1.1.2-0.20180615153820-ae375a99d36a/testonly/integration/port.go (about)

     1  // Copyright 2017 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package integration
    16  
    17  import (
    18  	"fmt"
    19  	"net"
    20  )
    21  
    22  // listen opens a random high numbered port for listening.
    23  func listen() (string, net.Listener, error) {
    24  	lis, err := net.Listen("tcp", "127.0.0.1:0")
    25  	if err != nil {
    26  		return "", nil, fmt.Errorf("failed to listen: %v", err)
    27  	}
    28  	_, port, err := net.SplitHostPort(lis.Addr().String())
    29  	if err != nil {
    30  		return "", nil, fmt.Errorf("unrecognized format for listen address %v: %v", lis.Addr().String(), err)
    31  	}
    32  	addr := "localhost:" + port
    33  	return addr, lis, nil
    34  }