AdGuardHome/helpers.go

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package main
import (
"bufio"
"context"
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"errors"
"fmt"
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"io"
"net"
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"net/http"
"net/url"
"os"
"path"
"path/filepath"
"runtime"
"strconv"
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"strings"
"syscall"
"time"
"github.com/AdguardTeam/dnsproxy/upstream"
"github.com/AdguardTeam/golibs/log"
"github.com/joomcode/errorx"
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)
// ----------------------------------
// helper functions for HTTP handlers
// ----------------------------------
func ensure(method string, handler func(http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
if r.Method != method {
http.Error(w, "This request must be "+method, http.StatusMethodNotAllowed)
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return
}
if method == "POST" || method == "PUT" || method == "DELETE" {
controlLock.Lock()
defer controlLock.Unlock()
}
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handler(w, r)
}
}
func ensurePOST(handler func(http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {
return ensure("POST", handler)
}
func ensureGET(handler func(http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {
return ensure("GET", handler)
}
// Bridge between http.Handler object and Go function
type httpHandler struct {
handler func(http.ResponseWriter, *http.Request)
}
func (h *httpHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
h.handler(w, r)
}
func ensureGETHandler(handler func(http.ResponseWriter, *http.Request)) http.Handler {
h := httpHandler{}
h.handler = ensure("GET", handler)
return &h
}
func optionalAuth(handler func(http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
if config.AuthName == "" || config.AuthPass == "" {
handler(w, r)
return
}
user, pass, ok := r.BasicAuth()
if !ok || user != config.AuthName || pass != config.AuthPass {
w.Header().Set("WWW-Authenticate", `Basic realm="dnsfilter"`)
w.WriteHeader(http.StatusUnauthorized)
w.Write([]byte("Unauthorised.\n"))
return
}
handler(w, r)
}
}
type authHandler struct {
handler http.Handler
}
func (a *authHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
optionalAuth(a.handler.ServeHTTP)(w, r)
}
func optionalAuthHandler(handler http.Handler) http.Handler {
return &authHandler{handler}
}
// -------------------
// first run / install
// -------------------
func detectFirstRun() bool {
configfile := config.ourConfigFilename
if !filepath.IsAbs(configfile) {
configfile = filepath.Join(config.ourWorkingDir, config.ourConfigFilename)
}
_, err := os.Stat(configfile)
if !os.IsNotExist(err) {
// do nothing, file exists
return false
}
return true
}
// preInstall lets the handler run only if firstRun is true, no redirects
func preInstall(handler func(http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
if !config.firstRun {
// if it's not first run, don't let users access it (for example /install.html when configuration is done)
http.Error(w, http.StatusText(http.StatusForbidden), http.StatusForbidden)
return
}
handler(w, r)
}
}
// preInstallStruct wraps preInstall into a struct that can be returned as an interface where necessary
type preInstallHandlerStruct struct {
handler http.Handler
}
func (p *preInstallHandlerStruct) ServeHTTP(w http.ResponseWriter, r *http.Request) {
preInstall(p.handler.ServeHTTP)(w, r)
}
// preInstallHandler returns http.Handler interface for preInstall wrapper
func preInstallHandler(handler http.Handler) http.Handler {
return &preInstallHandlerStruct{handler}
}
// postInstall lets the handler run only if firstRun is false, and redirects to /install.html otherwise
// it also enforces HTTPS if it is enabled and configured
func postInstall(handler func(http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {
return func(w http.ResponseWriter, r *http.Request) {
if config.firstRun &&
!strings.HasPrefix(r.URL.Path, "/install.") &&
r.URL.Path != "/favicon.ico" {
http.Redirect(w, r, "/install.html", http.StatusSeeOther) // should not be cacheable
return
}
// enforce https?
if config.TLS.ForceHTTPS && r.TLS == nil && config.TLS.Enabled && config.TLS.PortHTTPS != 0 && httpsServer.server != nil {
// yes, and we want host from host:port
host, _, err := net.SplitHostPort(r.Host)
if err != nil {
// no port in host
host = r.Host
}
// construct new URL to redirect to
newURL := url.URL{
Scheme: "https",
Host: net.JoinHostPort(host, strconv.Itoa(config.TLS.PortHTTPS)),
Path: r.URL.Path,
RawQuery: r.URL.RawQuery,
}
http.Redirect(w, r, newURL.String(), http.StatusTemporaryRedirect)
return
}
w.Header().Set("Access-Control-Allow-Origin", "*")
handler(w, r)
}
}
type postInstallHandlerStruct struct {
handler http.Handler
}
func (p *postInstallHandlerStruct) ServeHTTP(w http.ResponseWriter, r *http.Request) {
postInstall(p.handler.ServeHTTP)(w, r)
}
func postInstallHandler(handler http.Handler) http.Handler {
return &postInstallHandlerStruct{handler}
}
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// -------------------------------------------------
// helper functions for parsing parameters from body
// -------------------------------------------------
func parseParametersFromBody(r io.Reader) (map[string]string, error) {
parameters := map[string]string{}
scanner := bufio.NewScanner(r)
for scanner.Scan() {
line := scanner.Text()
if len(line) == 0 {
// skip empty lines
continue
}
parts := strings.SplitN(line, "=", 2)
if len(parts) != 2 {
return parameters, errors.New("Got invalid request body")
}
parameters[strings.TrimSpace(parts[0])] = strings.TrimSpace(parts[1])
}
return parameters, nil
}
// ------------------
// network interfaces
// ------------------
type netInterface struct {
Name string `json:"name"`
MTU int `json:"mtu"`
HardwareAddr string `json:"hardware_address"`
Addresses []string `json:"ip_addresses"`
Flags string `json:"flags"`
}
// getValidNetInterfaces returns interfaces that are eligible for DNS and/or DHCP
// invalid interface is a ppp interface or the one that doesn't allow broadcasts
func getValidNetInterfaces() ([]net.Interface, error) {
ifaces, err := net.Interfaces()
if err != nil {
return nil, fmt.Errorf("Couldn't get list of interfaces: %s", err)
}
netIfaces := []net.Interface{}
for i := range ifaces {
if ifaces[i].Flags&net.FlagPointToPoint != 0 {
// this interface is ppp, we're not interested in this one
continue
}
iface := ifaces[i]
netIfaces = append(netIfaces, iface)
}
return netIfaces, nil
}
// getValidNetInterfacesMap returns interfaces that are eligible for DNS and WEB only
// we do not return link-local addresses here
func getValidNetInterfacesForWeb() ([]netInterface, error) {
ifaces, err := getValidNetInterfaces()
if err != nil {
return nil, errorx.Decorate(err, "Couldn't get interfaces")
}
if len(ifaces) == 0 {
return nil, errors.New("couldn't find any legible interface")
}
var netInterfaces []netInterface
for _, iface := range ifaces {
addrs, e := iface.Addrs()
if e != nil {
return nil, errorx.Decorate(e, "Failed to get addresses for interface %s", iface.Name)
}
netIface := netInterface{
Name: iface.Name,
MTU: iface.MTU,
HardwareAddr: iface.HardwareAddr.String(),
}
if iface.Flags != 0 {
netIface.Flags = iface.Flags.String()
}
// we don't want link-local addresses in json, so skip them
for _, addr := range addrs {
ipnet, ok := addr.(*net.IPNet)
if !ok {
// not an IPNet, should not happen
return nil, fmt.Errorf("SHOULD NOT HAPPEN: got iface.Addrs() element %s that is not net.IPNet, it is %T", addr, addr)
}
// ignore link-local
if ipnet.IP.IsLinkLocalUnicast() {
continue
}
netIface.Addresses = append(netIface.Addresses, ipnet.IP.String())
}
if len(netIface.Addresses) != 0 {
netInterfaces = append(netInterfaces, netIface)
}
}
return netInterfaces, nil
}
// checkPortAvailable is not a cheap test to see if the port is bindable, because it's actually doing the bind momentarily
func checkPortAvailable(host string, port int) error {
ln, err := net.Listen("tcp", net.JoinHostPort(host, strconv.Itoa(port)))
if err != nil {
return err
}
ln.Close()
return nil
}
func checkPacketPortAvailable(host string, port int) error {
ln, err := net.ListenPacket("udp", net.JoinHostPort(host, strconv.Itoa(port)))
if err != nil {
return err
}
ln.Close()
return err
}
// Connect to a remote server resolving hostname using our own DNS server
func customDialContext(ctx context.Context, network, addr string) (net.Conn, error) {
log.Tracef("network:%v addr:%v", network, addr)
host, port, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
dialer := &net.Dialer{
Timeout: time.Minute * 5,
}
if net.ParseIP(host) != nil || config.DNS.Port == 0 {
con, err := dialer.DialContext(ctx, network, addr)
return con, err
}
bindhost := config.DNS.BindHost
if config.DNS.BindHost == "0.0.0.0" {
bindhost = "127.0.0.1"
}
resolverAddr := fmt.Sprintf("%s:%d", bindhost, config.DNS.Port)
r := upstream.NewResolver(resolverAddr, 30*time.Second)
addrs, e := r.LookupIPAddr(ctx, host)
log.Tracef("LookupIPAddr: %s: %v", host, addrs)
if e != nil {
return nil, e
}
var firstErr error
firstErr = nil
for _, a := range addrs {
addr = fmt.Sprintf("%s:%s", a.String(), port)
con, err := dialer.DialContext(ctx, network, addr)
if err != nil {
if firstErr == nil {
firstErr = err
}
continue
}
return con, err
}
return nil, firstErr
}
// check if error is "address already in use"
func errorIsAddrInUse(err error) bool {
errOpError, ok := err.(*net.OpError)
if !ok {
return false
}
errSyscallError, ok := errOpError.Err.(*os.SyscallError)
if !ok {
return false
}
errErrno, ok := errSyscallError.Err.(syscall.Errno)
if !ok {
return false
}
if runtime.GOOS == "windows" {
const WSAEADDRINUSE = 10048
return errErrno == WSAEADDRINUSE
}
return errErrno == syscall.EADDRINUSE
}
// ---------------------
// debug logging helpers
// ---------------------
func _Func() string {
pc := make([]uintptr, 10) // at least 1 entry needed
runtime.Callers(2, pc)
f := runtime.FuncForPC(pc[0])
return path.Base(f.Name())
}