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package hosts
import (
"bufio"
"fmt"
"io"
"net"
"strings"
)
// LocalNames represent host names that are considered local.
var LocalNames = []string{
"localhost",
"localhost.localdomain",
"local",
"broadcasthost",
"ip6-localhost",
"ip6-loopback",
"ip6-localnet",
"ip6-mcastprefix",
"ip6-allnodes",
"ip6-allrouters",
"ip6-allhosts",
"0.0.0.0",
}
// DefaultParser is the default parser
var DefaultParser = &Parser{IgnoredHosts: LocalNames}
// Parser represents a hosts parser.
type Parser struct {
IgnoredHosts []string
}
// Hosts represents a hosts file.
type Hosts map[string][]net.IPAddr
// Parse uses DefaultParser to parse hosts from reader r.
func Parse(r io.Reader) (Hosts, error) {
return DefaultParser.Parse(r)
}
// Get returns the IP addresses of name.
func (h Hosts) Get(name string) ([]net.IPAddr, bool) {
ipAddrs, ok := h[name]
return ipAddrs, ok
}
// Del deletes the hosts entry of name.
func (h Hosts) Del(name string) {
delete(h, name)
}
func (p *Parser) ignore(name string) bool {
for _, ignored := range p.IgnoredHosts {
if ignored == name {
return true
}
}
return false
}
// Parse parses hosts from reader r.
func (p *Parser) Parse(r io.Reader) (Hosts, error) {
entries := make(map[string][]net.IPAddr)
scanner := bufio.NewScanner(r)
n := 0
for scanner.Scan() {
n++
line := scanner.Text()
fields := strings.Fields(line)
if len(fields) < 2 {
continue
}
ip := fields[0]
if strings.HasPrefix(ip, "#") {
continue
}
ipAddr, err := net.ResolveIPAddr("", ip)
if err != nil {
return nil, fmt.Errorf("line %d: invalid ip address: %s - %s", n, fields[0], line)
}
for _, name := range fields[1:] {
if strings.HasPrefix(name, "#") {
break
}
if p.ignore(name) {
continue
}
entries[name] = append(entries[name], *ipAddr)
}
}
return entries, nil
}
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