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