AdGuardHome/internal/dhcpd/http.go
Ainar Garipov 313fd7107f Pull request: all: imp code, err handling
Closes .

Squashed commit of the following:

commit a5b50ee011a995f4ab3d93314acd6f0ca82d99cf
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Mar 15 14:05:25 2021 +0300

    all: imp code

commit bc610f8f438549e8c6b04c8a213b5422dda2aff5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Mar 12 20:00:14 2021 +0300

    all: imp code, err handling
2021-03-15 14:19:04 +03:00

583 lines
15 KiB
Go

package dhcpd
import (
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"net"
"net/http"
"os"
"strings"
"github.com/AdguardTeam/AdGuardHome/internal/sysutil"
"github.com/AdguardTeam/AdGuardHome/internal/util"
"github.com/AdguardTeam/golibs/log"
)
func httpError(r *http.Request, w http.ResponseWriter, code int, format string, args ...interface{}) {
text := fmt.Sprintf(format, args...)
log.Info("DHCP: %s %s: %s", r.Method, r.URL, text)
http.Error(w, text, code)
}
type v4ServerConfJSON struct {
GatewayIP net.IP `json:"gateway_ip"`
SubnetMask net.IP `json:"subnet_mask"`
RangeStart net.IP `json:"range_start"`
RangeEnd net.IP `json:"range_end"`
LeaseDuration uint32 `json:"lease_duration"`
}
func v4JSONToServerConf(j *v4ServerConfJSON) V4ServerConf {
if j == nil {
return V4ServerConf{}
}
return V4ServerConf{
GatewayIP: j.GatewayIP,
SubnetMask: j.SubnetMask,
RangeStart: j.RangeStart,
RangeEnd: j.RangeEnd,
LeaseDuration: j.LeaseDuration,
}
}
type v6ServerConfJSON struct {
RangeStart net.IP `json:"range_start"`
LeaseDuration uint32 `json:"lease_duration"`
}
func v6JSONToServerConf(j *v6ServerConfJSON) V6ServerConf {
if j == nil {
return V6ServerConf{}
}
return V6ServerConf{
RangeStart: j.RangeStart,
LeaseDuration: j.LeaseDuration,
}
}
// dhcpStatusResponse is the response for /control/dhcp/status endpoint.
type dhcpStatusResponse struct {
Enabled bool `json:"enabled"`
IfaceName string `json:"interface_name"`
V4 V4ServerConf `json:"v4"`
V6 V6ServerConf `json:"v6"`
Leases []Lease `json:"leases"`
StaticLeases []Lease `json:"static_leases"`
}
func (s *Server) handleDHCPStatus(w http.ResponseWriter, r *http.Request) {
status := &dhcpStatusResponse{
Enabled: s.conf.Enabled,
IfaceName: s.conf.InterfaceName,
V4: V4ServerConf{},
V6: V6ServerConf{},
}
s.srv4.WriteDiskConfig4(&status.V4)
s.srv6.WriteDiskConfig6(&status.V6)
status.Leases = s.Leases(LeasesDynamic)
status.StaticLeases = s.Leases(LeasesStatic)
w.Header().Set("Content-Type", "application/json")
err := json.NewEncoder(w).Encode(status)
if err != nil {
httpError(r, w, http.StatusInternalServerError, "Unable to marshal DHCP status json: %s", err)
return
}
}
func (s *Server) enableDHCP(ifaceName string) (code int, err error) {
var hasStaticIP bool
hasStaticIP, err = sysutil.IfaceHasStaticIP(ifaceName)
if err != nil {
if errors.Is(err, os.ErrPermission) {
// ErrPermission may happen here on Linux systems where
// AdGuard Home is installed using Snap. That doesn't
// necessarily mean that the machine doesn't have
// a static IP, so we can assume that it has and go on.
// If the machine doesn't, we'll get an error later.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/2667.
//
// TODO(a.garipov): I was thinking about moving this
// into IfaceHasStaticIP, but then we wouldn't be able
// to log it. Think about it more.
log.Info("error while checking static ip: %s; "+
"assuming machine has static ip and going on", err)
hasStaticIP = true
} else if errors.Is(err, sysutil.ErrNoStaticIPInfo) {
// Couldn't obtain a definitive answer. Assume static
// IP an go on.
log.Info("can't check for static ip; " +
"assuming machine has static ip and going on")
hasStaticIP = true
} else {
err = fmt.Errorf("checking static ip: %w", err)
return http.StatusInternalServerError, err
}
}
if !hasStaticIP {
err = sysutil.IfaceSetStaticIP(ifaceName)
if err != nil {
err = fmt.Errorf("setting static ip: %w", err)
return http.StatusInternalServerError, err
}
}
err = s.Start()
if err != nil {
return http.StatusBadRequest, fmt.Errorf("starting dhcp server: %w", err)
}
return 0, nil
}
type dhcpServerConfigJSON struct {
V4 *v4ServerConfJSON `json:"v4"`
V6 *v6ServerConfJSON `json:"v6"`
InterfaceName string `json:"interface_name"`
Enabled nullBool `json:"enabled"`
}
func (s *Server) handleDHCPSetConfig(w http.ResponseWriter, r *http.Request) {
conf := dhcpServerConfigJSON{}
conf.Enabled = boolToNullBool(s.conf.Enabled)
conf.InterfaceName = s.conf.InterfaceName
err := json.NewDecoder(r.Body).Decode(&conf)
if err != nil {
httpError(r, w, http.StatusBadRequest,
"failed to parse new dhcp config json: %s", err)
return
}
var s4 DHCPServer
var s6 DHCPServer
v4Enabled := false
v6Enabled := false
if conf.V4 != nil {
v4Conf := v4JSONToServerConf(conf.V4)
v4Conf.Enabled = conf.Enabled == nbTrue
if len(v4Conf.RangeStart) == 0 {
v4Conf.Enabled = false
}
v4Enabled = v4Conf.Enabled
v4Conf.InterfaceName = conf.InterfaceName
c4 := V4ServerConf{}
s.srv4.WriteDiskConfig4(&c4)
v4Conf.notify = c4.notify
v4Conf.ICMPTimeout = c4.ICMPTimeout
s4, err = v4Create(v4Conf)
if err != nil {
httpError(r, w, http.StatusBadRequest,
"invalid dhcpv4 configuration: %s", err)
return
}
}
if conf.V6 != nil {
v6Conf := v6JSONToServerConf(conf.V6)
v6Conf.Enabled = conf.Enabled == nbTrue
if len(v6Conf.RangeStart) == 0 {
v6Conf.Enabled = false
}
// Don't overwrite the RA/SLAAC settings from the config file.
//
// TODO(a.garipov): Perhaps include them into the request to
// allow changing them from the HTTP API?
v6Conf.RASLAACOnly = s.conf.Conf6.RASLAACOnly
v6Conf.RAAllowSLAAC = s.conf.Conf6.RAAllowSLAAC
v6Enabled = v6Conf.Enabled
v6Conf.InterfaceName = conf.InterfaceName
v6Conf.notify = s.onNotify
s6, err = v6Create(v6Conf)
if err != nil {
httpError(r, w, http.StatusBadRequest,
"invalid dhcpv6 configuration: %s", err)
return
}
}
if conf.Enabled == nbTrue && !v4Enabled && !v6Enabled {
httpError(r, w, http.StatusBadRequest,
"dhcpv4 or dhcpv6 configuration must be complete")
return
}
s.Stop()
if conf.Enabled != nbNull {
s.conf.Enabled = conf.Enabled == nbTrue
}
if conf.InterfaceName != "" {
s.conf.InterfaceName = conf.InterfaceName
}
if s4 != nil {
s.srv4 = s4
}
if s6 != nil {
s.srv6 = s6
}
s.conf.ConfigModified()
s.dbLoad()
if s.conf.Enabled {
var code int
code, err = s.enableDHCP(conf.InterfaceName)
if err != nil {
httpError(r, w, code, "enabling dhcp: %s", err)
return
}
}
}
type netInterfaceJSON struct {
Name string `json:"name"`
GatewayIP net.IP `json:"gateway_ip"`
HardwareAddr string `json:"hardware_address"`
Addrs4 []net.IP `json:"ipv4_addresses"`
Addrs6 []net.IP `json:"ipv6_addresses"`
Flags string `json:"flags"`
}
func (s *Server) handleDHCPInterfaces(w http.ResponseWriter, r *http.Request) {
response := map[string]netInterfaceJSON{}
ifaces, err := util.GetValidNetInterfaces()
if err != nil {
httpError(r, w, http.StatusInternalServerError, "Couldn't get interfaces: %s", err)
return
}
for _, iface := range ifaces {
if iface.Flags&net.FlagLoopback != 0 {
// it's a loopback, skip it
continue
}
if iface.Flags&net.FlagBroadcast == 0 {
// this interface doesn't support broadcast, skip it
continue
}
var addrs []net.Addr
addrs, err = iface.Addrs()
if err != nil {
httpError(r, w, http.StatusInternalServerError, "Failed to get addresses for interface %s: %s", iface.Name, err)
return
}
jsonIface := netInterfaceJSON{
Name: iface.Name,
HardwareAddr: iface.HardwareAddr.String(),
}
if iface.Flags != 0 {
jsonIface.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
httpError(r, w, http.StatusInternalServerError, "SHOULD NOT HAPPEN: got iface.Addrs() element %s that is not net.IPNet, it is %T", addr, addr)
return
}
// ignore link-local
if ipnet.IP.IsLinkLocalUnicast() {
continue
}
if ipnet.IP.To4() != nil {
jsonIface.Addrs4 = append(jsonIface.Addrs4, ipnet.IP)
} else {
jsonIface.Addrs6 = append(jsonIface.Addrs6, ipnet.IP)
}
}
if len(jsonIface.Addrs4)+len(jsonIface.Addrs6) != 0 {
jsonIface.GatewayIP = sysutil.GatewayIP(iface.Name)
response[iface.Name] = jsonIface
}
}
err = json.NewEncoder(w).Encode(response)
if err != nil {
httpError(r, w, http.StatusInternalServerError, "Failed to marshal json with available interfaces: %s", err)
return
}
}
// dhcpSearchOtherResult contains information about other DHCP server for
// specific network interface.
type dhcpSearchOtherResult struct {
Found string `json:"found,omitempty"`
Error string `json:"error,omitempty"`
}
// dhcpStaticIPStatus contains information about static IP address for DHCP
// server.
type dhcpStaticIPStatus struct {
Static string `json:"static"`
IP string `json:"ip,omitempty"`
Error string `json:"error,omitempty"`
}
// dhcpSearchV4Result contains information about DHCPv4 server for specific
// network interface.
type dhcpSearchV4Result struct {
OtherServer dhcpSearchOtherResult `json:"other_server"`
StaticIP dhcpStaticIPStatus `json:"static_ip"`
}
// dhcpSearchV6Result contains information about DHCPv6 server for specific
// network interface.
type dhcpSearchV6Result struct {
OtherServer dhcpSearchOtherResult `json:"other_server"`
}
// dhcpSearchResult is a response for /control/dhcp/find_active_dhcp endpoint.
type dhcpSearchResult struct {
V4 dhcpSearchV4Result `json:"v4"`
V6 dhcpSearchV6Result `json:"v6"`
}
// Perform the following tasks:
// . Search for another DHCP server running
// . Check if a static IP is configured for the network interface
// Respond with results
func (s *Server) handleDHCPFindActiveServer(w http.ResponseWriter, r *http.Request) {
// This use of ReadAll is safe, because request's body is now limited.
body, err := ioutil.ReadAll(r.Body)
if err != nil {
msg := fmt.Sprintf("failed to read request body: %s", err)
log.Error(msg)
http.Error(w, msg, http.StatusBadRequest)
return
}
interfaceName := strings.TrimSpace(string(body))
if interfaceName == "" {
msg := "empty interface name specified"
log.Error(msg)
http.Error(w, msg, http.StatusBadRequest)
return
}
result := dhcpSearchResult{
V4: dhcpSearchV4Result{
OtherServer: dhcpSearchOtherResult{},
StaticIP: dhcpStaticIPStatus{},
},
V6: dhcpSearchV6Result{
OtherServer: dhcpSearchOtherResult{},
},
}
found4, err4 := CheckIfOtherDHCPServersPresentV4(interfaceName)
isStaticIP, err := sysutil.IfaceHasStaticIP(interfaceName)
if err != nil {
result.V4.StaticIP.Static = "error"
result.V4.StaticIP.Error = err.Error()
} else if !isStaticIP {
result.V4.StaticIP.Static = "no"
result.V4.StaticIP.IP = util.GetSubnet(interfaceName).String()
}
if found4 {
result.V4.OtherServer.Found = "yes"
} else if err4 != nil {
result.V4.OtherServer.Found = "error"
result.V4.OtherServer.Error = err4.Error()
}
found6, err6 := CheckIfOtherDHCPServersPresentV6(interfaceName)
if found6 {
result.V6.OtherServer.Found = "yes"
} else if err6 != nil {
result.V6.OtherServer.Found = "error"
result.V6.OtherServer.Error = err6.Error()
}
w.Header().Set("Content-Type", "application/json")
err = json.NewEncoder(w).Encode(result)
if err != nil {
httpError(r, w, http.StatusInternalServerError, "Failed to marshal DHCP found json: %s", err)
return
}
}
func (s *Server) handleDHCPAddStaticLease(w http.ResponseWriter, r *http.Request) {
lj := Lease{}
err := json.NewDecoder(r.Body).Decode(&lj)
if err != nil {
httpError(r, w, http.StatusBadRequest, "json.Decode: %s", err)
return
}
if lj.IP == nil {
httpError(r, w, http.StatusBadRequest, "invalid IP")
return
}
ip4 := lj.IP.To4()
if ip4 == nil {
lj.IP = lj.IP.To16()
err = s.srv6.AddStaticLease(lj)
if err != nil {
httpError(r, w, http.StatusBadRequest, "%s", err)
}
return
}
lj.IP = ip4
err = s.srv4.AddStaticLease(lj)
if err != nil {
httpError(r, w, http.StatusBadRequest, "%s", err)
return
}
}
func (s *Server) handleDHCPRemoveStaticLease(w http.ResponseWriter, r *http.Request) {
lj := Lease{}
err := json.NewDecoder(r.Body).Decode(&lj)
if err != nil {
httpError(r, w, http.StatusBadRequest, "json.Decode: %s", err)
return
}
if lj.IP == nil {
httpError(r, w, http.StatusBadRequest, "invalid IP")
return
}
ip4 := lj.IP.To4()
if ip4 == nil {
lj.IP = lj.IP.To16()
err = s.srv6.RemoveStaticLease(lj)
if err != nil {
httpError(r, w, http.StatusBadRequest, "%s", err)
}
return
}
lj.IP = ip4
err = s.srv4.RemoveStaticLease(lj)
if err != nil {
httpError(r, w, http.StatusBadRequest, "%s", err)
return
}
}
func (s *Server) handleReset(w http.ResponseWriter, r *http.Request) {
s.Stop()
err := os.Remove(s.conf.DBFilePath)
if err != nil && !errors.Is(err, os.ErrNotExist) {
log.Error("dhcp: removing %q: %s", s.conf.DBFilePath, err)
}
oldconf := s.conf
s.conf = ServerConfig{}
s.conf.WorkDir = oldconf.WorkDir
s.conf.HTTPRegister = oldconf.HTTPRegister
s.conf.ConfigModified = oldconf.ConfigModified
s.conf.DBFilePath = oldconf.DBFilePath
v4conf := V4ServerConf{}
v4conf.ICMPTimeout = 1000
v4conf.notify = s.onNotify
s.srv4, _ = v4Create(v4conf)
v6conf := V6ServerConf{}
v6conf.notify = s.onNotify
s.srv6, _ = v6Create(v6conf)
s.conf.ConfigModified()
}
func (s *Server) registerHandlers() {
s.conf.HTTPRegister(http.MethodGet, "/control/dhcp/status", s.handleDHCPStatus)
s.conf.HTTPRegister(http.MethodGet, "/control/dhcp/interfaces", s.handleDHCPInterfaces)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/set_config", s.handleDHCPSetConfig)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/find_active_dhcp", s.handleDHCPFindActiveServer)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/add_static_lease", s.handleDHCPAddStaticLease)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/remove_static_lease", s.handleDHCPRemoveStaticLease)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/reset", s.handleReset)
}
// jsonError is a generic JSON error response.
//
// TODO(a.garipov): Merge together with the implementations in .../home and
// other packages after refactoring the web handler registering.
type jsonError struct {
// Message is the error message, an opaque string.
Message string `json:"message"`
}
// notImplemented returns a handler that replies to any request with an HTTP 501
// Not Implemented status and a JSON error with the provided message msg.
//
// TODO(a.garipov): Either take the logger from the server after we've
// refactored logging or make this not a method of *Server.
func (s *Server) notImplemented(msg string) (f func(http.ResponseWriter, *http.Request)) {
return func(w http.ResponseWriter, _ *http.Request) {
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusNotImplemented)
err := json.NewEncoder(w).Encode(&jsonError{
Message: msg,
})
if err != nil {
log.Debug("writing 501 json response: %s", err)
}
}
}
func (s *Server) registerNotImplementedHandlers() {
h := s.notImplemented("dhcp is not supported on windows")
s.conf.HTTPRegister(http.MethodGet, "/control/dhcp/status", h)
s.conf.HTTPRegister(http.MethodGet, "/control/dhcp/interfaces", h)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/set_config", h)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/find_active_dhcp", h)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/add_static_lease", h)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/remove_static_lease", h)
s.conf.HTTPRegister(http.MethodPost, "/control/dhcp/reset", h)
}