70 lines
1.6 KiB
Go
70 lines
1.6 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build darwin freebsd linux netbsd openbsd
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// Read system port mappings from /etc/services
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package net
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import "sync"
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var services map[string]map[string]int
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var servicesError error
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var onceReadServices sync.Once
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func readServices() {
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services = make(map[string]map[string]int)
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var file *file
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if file, servicesError = open("/etc/services"); servicesError != nil {
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return
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}
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for line, ok := file.readLine(); ok; line, ok = file.readLine() {
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// "http 80/tcp www www-http # World Wide Web HTTP"
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if i := byteIndex(line, '#'); i >= 0 {
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line = line[0:i]
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}
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f := getFields(line)
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if len(f) < 2 {
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continue
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}
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portnet := f[1] // "tcp/80"
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port, j, ok := dtoi(portnet, 0)
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if !ok || port <= 0 || j >= len(portnet) || portnet[j] != '/' {
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continue
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}
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netw := portnet[j+1:] // "tcp"
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m, ok1 := services[netw]
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if !ok1 {
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m = make(map[string]int)
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services[netw] = m
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}
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for i := 0; i < len(f); i++ {
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if i != 1 { // f[1] was port/net
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m[f[i]] = port
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}
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}
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}
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file.close()
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}
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// goLookupPort is the native Go implementation of LookupPort.
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func goLookupPort(network, service string) (port int, err error) {
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onceReadServices.Do(readServices)
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switch network {
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case "tcp4", "tcp6":
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network = "tcp"
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case "udp4", "udp6":
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network = "udp"
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}
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if m, ok := services[network]; ok {
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if port, ok = m[service]; ok {
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return
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}
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}
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return 0, &AddrError{"unknown port", network + "/" + service}
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}
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