Source file src/pkg/net/port_unix.go

     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 aix darwin dragonfly freebsd js,wasm linux netbsd openbsd solaris nacl
     6	
     7	// Read system port mappings from /etc/services
     8	
     9	package net
    10	
    11	import (
    12		"internal/bytealg"
    13		"sync"
    14	)
    15	
    16	var onceReadServices sync.Once
    17	
    18	func readServices() {
    19		file, err := open("/etc/services")
    20		if err != nil {
    21			return
    22		}
    23		defer file.close()
    24	
    25		for line, ok := file.readLine(); ok; line, ok = file.readLine() {
    26			// "http 80/tcp www www-http # World Wide Web HTTP"
    27			if i := bytealg.IndexByteString(line, '#'); i >= 0 {
    28				line = line[:i]
    29			}
    30			f := getFields(line)
    31			if len(f) < 2 {
    32				continue
    33			}
    34			portnet := f[1] // "80/tcp"
    35			port, j, ok := dtoi(portnet)
    36			if !ok || port <= 0 || j >= len(portnet) || portnet[j] != '/' {
    37				continue
    38			}
    39			netw := portnet[j+1:] // "tcp"
    40			m, ok1 := services[netw]
    41			if !ok1 {
    42				m = make(map[string]int)
    43				services[netw] = m
    44			}
    45			for i := 0; i < len(f); i++ {
    46				if i != 1 { // f[1] was port/net
    47					m[f[i]] = port
    48				}
    49			}
    50		}
    51	}
    52	
    53	// goLookupPort is the native Go implementation of LookupPort.
    54	func goLookupPort(network, service string) (port int, err error) {
    55		onceReadServices.Do(readServices)
    56		return lookupPortMap(network, service)
    57	}
    58	

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