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environment_linux.go
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environment_linux.go
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package netenv
import (
"bufio"
"encoding/hex"
"net"
"os"
"strings"
"sync"
"time"
"github.com/miekg/dns"
"github.com/safing/portbase/log"
"github.com/safing/portmaster/network/netutils"
)
const (
gatewaysRecheck = 2 * time.Second
nameserversRecheck = 2 * time.Second
)
var (
gateways = make([]*net.IP, 0)
gatewaysLock sync.Mutex
gatewaysExpires = time.Now()
nameservers = make([]Nameserver, 0)
nameserversLock sync.Mutex
nameserversExpires = time.Now()
)
// Gateways returns the currently active gateways.
func Gateways() []*net.IP {
// locking
gatewaysLock.Lock()
defer gatewaysLock.Unlock()
// cache
if gatewaysExpires.After(time.Now()) {
return gateways
}
// update cache expiry when finished
defer func() {
gatewaysExpires = time.Now().Add(gatewaysRecheck)
}()
// logic
newGateways := make([]*net.IP, 0)
var decoded []byte
// open file
route, err := os.Open("/proc/net/route")
if err != nil {
log.Warningf("environment: could not read /proc/net/route: %s", err)
return newGateways
}
defer route.Close()
// file scanner
scanner := bufio.NewScanner(route)
scanner.Split(bufio.ScanLines)
// parse
for scanner.Scan() {
line := strings.SplitN(scanner.Text(), "\t", 4)
if len(line) < 4 {
continue
}
if line[1] == "00000000" {
decoded, err = hex.DecodeString(line[2])
if err != nil {
log.Warningf("environment: could not parse gateway %s from /proc/net/route: %s", line[2], err)
continue
}
if len(decoded) != 4 {
log.Warningf("environment: decoded gateway %s from /proc/net/route has wrong length", decoded)
continue
}
gate := net.IPv4(decoded[3], decoded[2], decoded[1], decoded[0])
newGateways = append(newGateways, &gate)
}
}
// open file
v6route, err := os.Open("/proc/net/ipv6_route")
if err != nil {
log.Warningf("environment: could not read /proc/net/ipv6_route: %s", err)
return newGateways
}
defer v6route.Close()
// file scanner
scanner = bufio.NewScanner(v6route)
scanner.Split(bufio.ScanLines)
// parse
for scanner.Scan() {
line := strings.SplitN(scanner.Text(), " ", 6)
if len(line) < 6 {
continue
}
if line[0] == "00000000000000000000000000000000" && line[4] != "00000000000000000000000000000000" {
decoded, err := hex.DecodeString(line[4])
if err != nil {
log.Warningf("environment: could not parse gateway %s from /proc/net/ipv6_route: %s", line[2], err)
continue
}
if len(decoded) != 16 {
log.Warningf("environment: decoded gateway %s from /proc/net/ipv6_route has wrong length", decoded)
continue
}
gate := net.IP(decoded)
newGateways = append(newGateways, &gate)
}
}
return newGateways
}
// Nameservers returns the currently active nameservers.
func Nameservers() []Nameserver {
// locking
nameserversLock.Lock()
defer nameserversLock.Unlock()
// cache
if nameserversExpires.After(time.Now()) {
return nameservers
}
// update cache expiry when finished
defer func() {
nameserversExpires = time.Now().Add(nameserversRecheck)
}()
// logic
// TODO: try:
// 1. NetworkManager DBUS
// 2. /etc/resolv.conf
// 2.1. if /etc/resolv.conf has localhost nameserver, check for dnsmasq config (are there others?)
nameservers = make([]Nameserver, 0)
// get nameservers from DBUS
dbusNameservers, err := getNameserversFromDbus()
if err != nil {
log.Warningf("environment: could not get nameservers from dbus: %s", err)
} else {
nameservers = addNameservers(nameservers, dbusNameservers)
}
// get nameservers from /etc/resolv.conf
resolvconfNameservers, err := getNameserversFromResolvconf()
if err != nil {
log.Warningf("environment: could not get nameservers from resolvconf: %s", err)
} else {
nameservers = addNameservers(nameservers, resolvconfNameservers)
}
return nameservers
}
func getNameserversFromResolvconf() ([]Nameserver, error) {
// open file
resolvconf, err := os.Open("/etc/resolv.conf")
if err != nil {
log.Warningf("environment: could not read /etc/resolv.conf: %s", err)
return nil, err
}
defer resolvconf.Close()
// file scanner
scanner := bufio.NewScanner(resolvconf)
scanner.Split(bufio.ScanLines)
var searchDomains []string
var servers []net.IP
// parse
for scanner.Scan() {
line := strings.SplitN(scanner.Text(), " ", 3)
if len(line) < 2 {
continue
}
switch line[0] {
case "search":
if netutils.IsValidFqdn(dns.Fqdn(line[1])) {
searchDomains = append(searchDomains, line[1])
}
case "nameserver":
ip := net.ParseIP(line[1])
if ip != nil {
servers = append(servers, ip)
}
}
}
// build array
nameservers := make([]Nameserver, 0, len(servers))
for _, server := range servers {
nameservers = append(nameservers, Nameserver{
IP: server,
Search: searchDomains,
})
}
return nameservers, nil
}
func addNameservers(nameservers, newNameservers []Nameserver) []Nameserver {
for _, newNameserver := range newNameservers {
found := false
for _, nameserver := range nameservers {
if nameserver.IP.Equal(newNameserver.IP) {
found = true
break
}
}
if !found {
nameservers = append(nameservers, newNameserver)
}
}
return nameservers
}