From d18c222b1aef8cb991211ae78ba187b588712091 Mon Sep 17 00:00:00 2001
From: Simon Zolin <s.zolin@adguard.com>
Date: Fri, 24 May 2019 17:15:19 +0300
Subject: [PATCH] + control: /access/list, /access/set handlers

---
 AGHTechDoc.md     | 47 +++++++++++++++++++++++++
 control.go        |  3 ++
 control_access.go | 87 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 137 insertions(+)
 create mode 100644 control_access.go

diff --git a/AGHTechDoc.md b/AGHTechDoc.md
index c6f615f3..f4e4d4c7 100644
--- a/AGHTechDoc.md
+++ b/AGHTechDoc.md
@@ -24,6 +24,9 @@ Contents:
 	* "Enable DHCP" command
 	* Static IP check/set
 	* Add a static lease
+* DNS access settings
+	* List access settings
+	* Set access settings
 
 
 ## First startup
@@ -626,3 +629,47 @@ Response:
 Error response (Client not found):
 
 	400
+
+
+## DNS access settings
+
+There are low-level settings that can block undesired DNS requests.  "Blocking" means not responding to request.
+
+There are 3 types of access settings:
+* allowed_clients: Only these clients are allowed to make DNS requests.
+* disallowed_clients: These clients are not allowed to make DNS requests.
+* blocked_hosts: These hosts are not allowed to be resolved by a DNS request.
+
+
+### List access settings
+
+Request:
+
+	GET /control/access/list
+
+Response:
+
+	200 OK
+
+	{
+		allowed_clients: ["127.0.0.1", ...]
+		disallowed_clients: ["127.0.0.1", ...]
+		blocked_hosts: ["host.com", ...]
+	}
+
+
+### Set access settings
+
+Request:
+
+	POST /control/access/set
+
+	{
+		allowed_clients: ["127.0.0.1", ...]
+		disallowed_clients: ["127.0.0.1", ...]
+		blocked_hosts: ["host.com", ...]
+	}
+
+Response:
+
+	200 OK
diff --git a/control.go b/control.go
index 77970de2..e1113968 100644
--- a/control.go
+++ b/control.go
@@ -996,6 +996,9 @@ func registerControlHandlers() {
 	http.HandleFunc("/control/dhcp/add_static_lease", postInstall(optionalAuth(ensurePOST(handleDHCPAddStaticLease))))
 	http.HandleFunc("/control/dhcp/remove_static_lease", postInstall(optionalAuth(ensurePOST(handleDHCPRemoveStaticLease))))
 
+	http.HandleFunc("/control/access/list", postInstall(optionalAuth(ensureGET(handleAccessList))))
+	http.HandleFunc("/control/access/set", postInstall(optionalAuth(ensurePOST(handleAccessSet))))
+
 	RegisterTLSHandlers()
 	RegisterClientsHandlers()
 
diff --git a/control_access.go b/control_access.go
new file mode 100644
index 00000000..0c6fd800
--- /dev/null
+++ b/control_access.go
@@ -0,0 +1,87 @@
+package main
+
+import (
+	"encoding/json"
+	"net"
+	"net/http"
+
+	"github.com/AdguardTeam/golibs/log"
+)
+
+type accessListJSON struct {
+	AllowedClients    []string `json:"allowed_clients"`
+	DisallowedClients []string `json:"disallowed_clients"`
+	BlockedHosts      []string `json:"blocked_hosts"`
+}
+
+func handleAccessList(w http.ResponseWriter, r *http.Request) {
+	log.Tracef("%s %v", r.Method, r.URL)
+
+	controlLock.Lock()
+	j := accessListJSON{
+		AllowedClients:    config.DNS.AllowedClients,
+		DisallowedClients: config.DNS.DisallowedClients,
+		BlockedHosts:      config.DNS.BlockedHosts,
+	}
+	controlLock.Unlock()
+
+	w.Header().Set("Content-Type", "application/json")
+	err := json.NewEncoder(w).Encode(j)
+	if err != nil {
+		httpError(w, http.StatusInternalServerError, "json.Encode: %s", err)
+		return
+	}
+}
+
+func checkIPCIDRArray(src []string) error {
+	for _, s := range src {
+		ip := net.ParseIP(s)
+		if ip != nil {
+			continue
+		}
+
+		_, _, err := net.ParseCIDR(s)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func handleAccessSet(w http.ResponseWriter, r *http.Request) {
+	log.Tracef("%s %v", r.Method, r.URL)
+
+	j := accessListJSON{}
+	err := json.NewDecoder(r.Body).Decode(&j)
+	if err != nil {
+		httpError(w, http.StatusBadRequest, "json.Decode: %s", err)
+		return
+	}
+
+	err = checkIPCIDRArray(j.AllowedClients)
+	if err == nil {
+		err = checkIPCIDRArray(j.DisallowedClients)
+	}
+	if err != nil {
+		httpError(w, http.StatusBadRequest, "%s", err)
+		return
+	}
+
+	config.Lock()
+	config.DNS.AllowedClients = j.AllowedClients
+	config.DNS.DisallowedClients = j.DisallowedClients
+	config.DNS.BlockedHosts = j.BlockedHosts
+	config.Unlock()
+
+	log.Tracef("Update access lists: %d, %d, %d",
+		len(j.AllowedClients), len(j.DisallowedClients), len(j.BlockedHosts))
+
+	err = writeAllConfigsAndReloadDNS()
+	if err != nil {
+		httpError(w, http.StatusBadRequest, "%s", err)
+		return
+	}
+
+	returnOK(w)
+}