badguardhome/internal/aghnet/net_linux.go
Eugene Burkov 394c2f65e0 Pull request: 3435 openwrt detect
Merge in DNS/adguard-home from 3435-openwrt-detect to master

Updates #3435.

Squashed commit of the following:

commit 04b10f407ced1c85ac8089f980d79e9bbfe14e95
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Aug 13 19:02:55 2021 +0300

    aghos: fix windows build

commit d387cec5f9cae9256dccef8c666c02f2fb7449a2
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Aug 13 18:22:12 2021 +0300

    aghos: imp code, tests

commit 2450b98522eb032ec8658f3ef2384fc77b627cc6
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Aug 13 13:43:46 2021 +0300

    all: imp code, docs

commit 7fabba3a8dc70fe61dbaa8fd5445453816fe9ac7
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Aug 13 04:04:09 2021 +0300

    all: log changes

commit 7cc1235308caf09eb4c80c05a4f328b8d6909ec7
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Aug 13 03:33:13 2021 +0300

    querylog: repl with golibs

commit 84592087d3b2aca23613950bb203ff3c862624dc
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Aug 13 03:16:37 2021 +0300

    aghos: use filewalker

commit e4f2964b0e031c7a9a053e85c0ff7c792c772929
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Aug 13 00:34:20 2021 +0300

    aghos: mv recurrentchecker from aghnet
2021-08-13 19:20:17 +03:00

179 lines
4.6 KiB
Go

//go:build linux
// +build linux
package aghnet
import (
"bufio"
"fmt"
"io"
"net"
"os"
"strings"
"github.com/AdguardTeam/AdGuardHome/internal/aghos"
"github.com/AdguardTeam/golibs/errors"
"github.com/google/renameio/maybe"
"golang.org/x/sys/unix"
)
// dhcpcdStaticConfig checks if interface is configured by /etc/dhcpcd.conf to
// have a static IP.
func (n interfaceName) dhcpcdStaticConfig(r io.Reader) (subsources []string, cont bool, err error) {
s := bufio.NewScanner(r)
ifaceFound := findIfaceLine(s, string(n))
if !ifaceFound {
return nil, true, s.Err()
}
for s.Scan() {
line := strings.TrimSpace(s.Text())
fields := strings.Fields(line)
if len(fields) >= 2 &&
fields[0] == "static" &&
strings.HasPrefix(fields[1], "ip_address=") {
return nil, false, s.Err()
}
if len(fields) > 0 && fields[0] == "interface" {
// Another interface found.
break
}
}
return nil, true, s.Err()
}
// ifacesStaticConfig checks if the interface is configured by any file of
// /etc/network/interfaces format to have a static IP.
func (n interfaceName) ifacesStaticConfig(r io.Reader) (sub []string, cont bool, err error) {
s := bufio.NewScanner(r)
for s.Scan() {
line := strings.TrimSpace(s.Text())
if len(line) == 0 || line[0] == '#' {
continue
}
// TODO(e.burkov): As man page interfaces(5) says, a line may be
// extended across multiple lines by making the last character a
// backslash. Provide extended lines support.
fields := strings.Fields(line)
fieldsNum := len(fields)
// Man page interfaces(5) declares that interface definition
// should consist of the key word "iface" followed by interface
// name, and method at fourth field.
if fieldsNum >= 4 &&
fields[0] == "iface" && fields[1] == string(n) && fields[3] == "static" {
return nil, false, nil
}
if fieldsNum >= 2 && fields[0] == "source" {
sub = append(sub, fields[1])
}
}
return sub, true, s.Err()
}
func ifaceHasStaticIP(ifaceName string) (has bool, err error) {
// TODO(a.garipov): Currently, this function returns the first
// definitive result. So if /etc/dhcpcd.conf has a static IP while
// /etc/network/interfaces doesn't, it will return true. Perhaps this
// is not the most desirable behavior.
iface := interfaceName(ifaceName)
for _, pair := range []struct {
aghos.FileWalker
filename string
}{{
FileWalker: iface.dhcpcdStaticConfig,
filename: "/etc/dhcpcd.conf",
}, {
FileWalker: iface.ifacesStaticConfig,
filename: "/etc/network/interfaces",
}} {
has, err = pair.Walk(pair.filename)
if err != nil {
return false, err
}
if has {
return true, nil
}
}
return false, ErrNoStaticIPInfo
}
func canBindPrivilegedPorts() (can bool, err error) {
cnbs, err := unix.PrctlRetInt(unix.PR_CAP_AMBIENT, unix.PR_CAP_AMBIENT_IS_SET, unix.CAP_NET_BIND_SERVICE, 0, 0)
// Don't check the error because it's always nil on Linux.
adm, _ := aghos.HaveAdminRights()
return cnbs == 1 || adm, err
}
// findIfaceLine scans s until it finds the line that declares an interface with
// the given name. If findIfaceLine can't find the line, it returns false.
func findIfaceLine(s *bufio.Scanner, name string) (ok bool) {
for s.Scan() {
line := strings.TrimSpace(s.Text())
fields := strings.Fields(line)
if len(fields) == 2 && fields[0] == "interface" && fields[1] == name {
return true
}
}
return false
}
// ifaceSetStaticIP configures the system to retain its current IP on the
// interface through dhcpdc.conf.
func ifaceSetStaticIP(ifaceName string) (err error) {
ipNet := GetSubnet(ifaceName)
if ipNet.IP == nil {
return errors.Error("can't get IP address")
}
gatewayIP := GatewayIP(ifaceName)
add := dhcpcdConfIface(ifaceName, ipNet, gatewayIP, ipNet.IP)
body, err := os.ReadFile("/etc/dhcpcd.conf")
if err != nil && !errors.Is(err, os.ErrNotExist) {
return err
}
body = append(body, []byte(add)...)
err = maybe.WriteFile("/etc/dhcpcd.conf", body, 0o644)
if err != nil {
return fmt.Errorf("writing conf: %w", err)
}
return nil
}
// dhcpcdConfIface returns configuration lines for the dhcpdc.conf files that
// configure the interface to have a static IP.
func dhcpcdConfIface(ifaceName string, ipNet *net.IPNet, gatewayIP, dnsIP net.IP) (conf string) {
var body []byte
add := fmt.Sprintf(
"\n# %[1]s added by AdGuard Home.\ninterface %[1]s\nstatic ip_address=%s\n",
ifaceName,
ipNet)
body = append(body, []byte(add)...)
if gatewayIP != nil {
add = fmt.Sprintf("static routers=%s\n", gatewayIP)
body = append(body, []byte(add)...)
}
add = fmt.Sprintf("static domain_name_servers=%s\n\n", dnsIP)
body = append(body, []byte(add)...)
return string(body)
}