port_unix.go

Documentation: net

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build darwin dragonfly freebsd linux netbsd openbsd solaris nacl
     6  
     7  // Read system port mappings from /etc/services
     8  
     9  package net
    10  
    11  import "sync"
    12  
    13  var onceReadServices sync.Once
    14  
    15  func readServices() {
    16  	file, err := open("/etc/services")
    17  	if err != nil {
    18  		return
    19  	}
    20  	defer file.close()
    21  
    22  	for line, ok := file.readLine(); ok; line, ok = file.readLine() {
    23  		// "http 80/tcp www www-http # World Wide Web HTTP"
    24  		if i := byteIndex(line, '#'); i >= 0 {
    25  			line = line[:i]
    26  		}
    27  		f := getFields(line)
    28  		if len(f) < 2 {
    29  			continue
    30  		}
    31  		portnet := f[1] // "80/tcp"
    32  		port, j, ok := dtoi(portnet)
    33  		if !ok || port <= 0 || j >= len(portnet) || portnet[j] != '/' {
    34  			continue
    35  		}
    36  		netw := portnet[j+1:] // "tcp"
    37  		m, ok1 := services[netw]
    38  		if !ok1 {
    39  			m = make(map[string]int)
    40  			services[netw] = m
    41  		}
    42  		for i := 0; i < len(f); i++ {
    43  			if i != 1 { // f[1] was port/net
    44  				m[f[i]] = port
    45  			}
    46  		}
    47  	}
    48  }
    49  
    50  // goLookupPort is the native Go implementation of LookupPort.
    51  func goLookupPort(network, service string) (port int, err error) {
    52  	onceReadServices.Do(readServices)
    53  	return lookupPortMap(network, service)
    54  }
    55
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