/usr/share/gocode/src/github.com/docker/libnetwork/drivers/bridge/resolvconf.go is in golang-github-docker-libnetwork-dev 0.8.0-dev.2+git20170202.599.45b4086-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 | package bridge
import (
"bytes"
"io/ioutil"
"regexp"
)
const (
ipv4NumBlock = `(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)`
ipv4Address = `(` + ipv4NumBlock + `\.){3}` + ipv4NumBlock
// This is not an IPv6 address verifier as it will accept a super-set of IPv6, and also
// will *not match* IPv4-Embedded IPv6 Addresses (RFC6052), but that and other variants
// -- e.g. other link-local types -- either won't work in containers or are unnecessary.
// For readability and sufficiency for Docker purposes this seemed more reasonable than a
// 1000+ character regexp with exact and complete IPv6 validation
ipv6Address = `([0-9A-Fa-f]{0,4}:){2,7}([0-9A-Fa-f]{0,4})`
)
var nsRegexp = regexp.MustCompile(`^\s*nameserver\s*((` + ipv4Address + `)|(` + ipv6Address + `))\s*$`)
func readResolvConf() ([]byte, error) {
resolv, err := ioutil.ReadFile("/etc/resolv.conf")
if err != nil {
return nil, err
}
return resolv, nil
}
// getLines parses input into lines and strips away comments.
func getLines(input []byte, commentMarker []byte) [][]byte {
lines := bytes.Split(input, []byte("\n"))
var output [][]byte
for _, currentLine := range lines {
var commentIndex = bytes.Index(currentLine, commentMarker)
if commentIndex == -1 {
output = append(output, currentLine)
} else {
output = append(output, currentLine[:commentIndex])
}
}
return output
}
// GetNameserversAsCIDR returns nameservers (if any) listed in
// /etc/resolv.conf as CIDR blocks (e.g., "1.2.3.4/32")
// This function's output is intended for net.ParseCIDR
func getNameserversAsCIDR(resolvConf []byte) []string {
nameservers := []string{}
for _, nameserver := range getNameservers(resolvConf) {
nameservers = append(nameservers, nameserver+"/32")
}
return nameservers
}
// GetNameservers returns nameservers (if any) listed in /etc/resolv.conf
func getNameservers(resolvConf []byte) []string {
nameservers := []string{}
for _, line := range getLines(resolvConf, []byte("#")) {
var ns = nsRegexp.FindSubmatch(line)
if len(ns) > 0 {
nameservers = append(nameservers, string(ns[1]))
}
}
return nameservers
}
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