128 lines
3.1 KiB
Go
128 lines
3.1 KiB
Go
package etchosts
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import (
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"bytes"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"regexp"
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)
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// Record Structure for a single host record
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type Record struct {
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Hosts string
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IP string
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}
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// WriteTo writes record to file and returns bytes written or error
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func (r Record) WriteTo(w io.Writer) (int64, error) {
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n, err := fmt.Fprintf(w, "%s\t%s\n", r.IP, r.Hosts)
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return int64(n), err
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}
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// Default hosts config records slice
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var defaultContent = []Record{
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{Hosts: "localhost", IP: "127.0.0.1"},
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{Hosts: "localhost ip6-localhost ip6-loopback", IP: "::1"},
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{Hosts: "ip6-localnet", IP: "fe00::0"},
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{Hosts: "ip6-mcastprefix", IP: "ff00::0"},
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{Hosts: "ip6-allnodes", IP: "ff02::1"},
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{Hosts: "ip6-allrouters", IP: "ff02::2"},
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}
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// Build function
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// path is path to host file string required
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// IP, hostname, and domainname set main record leave empty for no master record
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// extraContent is an array of extra host records.
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func Build(path, IP, hostname, domainname string, extraContent []Record) error {
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content := bytes.NewBuffer(nil)
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if IP != "" {
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//set main record
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var mainRec Record
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mainRec.IP = IP
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if domainname != "" {
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mainRec.Hosts = fmt.Sprintf("%s.%s %s", hostname, domainname, hostname)
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} else {
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mainRec.Hosts = hostname
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}
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if _, err := mainRec.WriteTo(content); err != nil {
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return err
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}
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}
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// Write defaultContent slice to buffer
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for _, r := range defaultContent {
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if _, err := r.WriteTo(content); err != nil {
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return err
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}
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}
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// Write extra content from function arguments
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for _, r := range extraContent {
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if _, err := r.WriteTo(content); err != nil {
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return err
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}
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}
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return ioutil.WriteFile(path, content.Bytes(), 0644)
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}
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// Add adds an arbitrary number of Records to an already existing /etc/hosts file
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func Add(path string, recs []Record) error {
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if len(recs) == 0 {
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return nil
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}
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f, err := os.Open(path)
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if err != nil {
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return err
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}
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content := bytes.NewBuffer(nil)
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_, err = content.ReadFrom(f)
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if err != nil {
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return err
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}
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for _, r := range recs {
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if _, err := r.WriteTo(content); err != nil {
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return err
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}
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}
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return ioutil.WriteFile(path, content.Bytes(), 0644)
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}
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// Delete deletes an arbitrary number of Records already existing in /etc/hosts file
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func Delete(path string, recs []Record) error {
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if len(recs) == 0 {
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return nil
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}
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old, err := ioutil.ReadFile(path)
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if err != nil {
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return err
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}
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regexpStr := fmt.Sprintf("\\S*\\t%s\\n", regexp.QuoteMeta(recs[0].Hosts))
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for _, r := range recs[1:] {
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regexpStr = regexpStr + "|" + fmt.Sprintf("\\S*\\t%s\\n", regexp.QuoteMeta(r.Hosts))
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}
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var re = regexp.MustCompile(regexpStr)
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return ioutil.WriteFile(path, re.ReplaceAll(old, []byte("")), 0644)
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}
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// Update all IP addresses where hostname matches.
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// path is path to host file
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// IP is new IP address
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// hostname is hostname to search for to replace IP
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func Update(path, IP, hostname string) error {
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old, err := ioutil.ReadFile(path)
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if err != nil {
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return err
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}
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var re = regexp.MustCompile(fmt.Sprintf("(\\S*)(\\t%s)", regexp.QuoteMeta(hostname)))
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return ioutil.WriteFile(path, re.ReplaceAll(old, []byte(IP+"$2")), 0644)
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}
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