Pull request #1005: home: imp large req handling

Merge in DNS/adguard-home from 2675-larger-requests to master

Updates #2675.

Squashed commit of the following:

commit 2b45c9bfdc817980204b11de768b425fb72a6488
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Feb 15 13:38:44 2021 +0300

    home: imp names

commit dad39ae7ee35346ea91f15665acc93ba0b5653df
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Feb 15 13:31:53 2021 +0300

    home: imp large req handling

CHANGELOG.md

@@ -23,8 +23,8 @@ and this project adheres to
   longer prevent the DHCP server from starting ([#2667]).
 - The server name sent by clients of TLS APIs is not only checked when
   `strict_sni_check` is enabled ([#2664]).
-- HTTP API request body size limit for the `POST /control/access/set` HTTP API
-  is increased ([#2666]).
+- HTTP API request body size limit for the `POST /control/access/set` and `POST
+  /control/filtering/set_rules` HTTP APIs is increased ([#2666], [#2675]).
 
 ### Fixed
 
@@ -45,6 +45,7 @@ and this project adheres to
 [#2664]: https://github.com/AdguardTeam/AdGuardHome/issues/2664
 [#2666]: https://github.com/AdguardTeam/AdGuardHome/issues/2666
 [#2667]: https://github.com/AdguardTeam/AdGuardHome/issues/2667
+[#2675]: https://github.com/AdguardTeam/AdGuardHome/issues/2675
 [#2678]: https://github.com/AdguardTeam/AdGuardHome/issues/2678
 
 

internal/home/middlewares.go

@@ -22,8 +22,30 @@ func withMiddlewares(h http.Handler, middlewares ...middleware) (wrapped http.Ha
 	return wrapped
 }
 
-// RequestBodySizeLimit is maximum request body length in bytes.
-const RequestBodySizeLimit = 64 * 1024
+// defaultReqBodySzLim is the default maximum request body size.
+const defaultReqBodySzLim = 64 * 1024
+
+// largerReqBodySzLim is the maximum request body size for APIs expecting larger
+// requests.
+const largerReqBodySzLim = 4 * 1024 * 1024
+
+// expectsLargerRequests shows if this request should use a larger body size
+// limit.  These are exceptions for poorly designed current APIs as well as APIs
+// that are designed to expect large files and requests.  Remove once the new,
+// better APIs are up.
+//
+// See https://github.com/AdguardTeam/AdGuardHome/issues/2666 and
+// https://github.com/AdguardTeam/AdGuardHome/issues/2675.
+func expectsLargerRequests(r *http.Request) (ok bool) {
+	m := r.Method
+	if m != http.MethodPost {
+		return false
+	}
+
+	p := r.URL.Path
+	return p == "/control/access/set" ||
+		p == "/control/filtering/set_rules"
+}
 
 // limitRequestBody wraps underlying handler h, making it's request's body Read
 // method limited.
@@ -31,16 +53,12 @@ func limitRequestBody(h http.Handler) (limited http.Handler) {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		var err error
 
-		var bodySizeLimit int64 = RequestBodySizeLimit
-		if u := r.URL; u.Path == "/control/access/set" {
-			// An exception for a poorly designed API.  Remove once
-			// the new, better API is up.
-			//
-			// See https://github.com/AdguardTeam/AdGuardHome/issues/2666.
-			bodySizeLimit *= 4
+		var szLim int64 = defaultReqBodySzLim
+		if expectsLargerRequests(r) {
+			szLim = largerReqBodySzLim
 		}
 
-		r.Body, err = aghio.LimitReadCloser(r.Body, bodySizeLimit)
+		r.Body, err = aghio.LimitReadCloser(r.Body, szLim)
 		if err != nil {
 			log.Error("limitRequestBody: %s", err)
 

internal/home/middlewares_test.go

@@ -14,7 +14,7 @@ import (
 
 func TestLimitRequestBody(t *testing.T) {
 	errReqLimitReached := &aghio.LimitReachedError{
-		Limit: RequestBodySizeLimit,
+		Limit: defaultReqBodySzLim,
 	}
 
 	testCases := []struct {
@@ -29,8 +29,8 @@ func TestLimitRequestBody(t *testing.T) {
 		wantErr: nil,
 	}, {
 		name:    "so_big",
-		body:    string(make([]byte, RequestBodySizeLimit+1)),
-		want:    make([]byte, RequestBodySizeLimit),
+		body:    string(make([]byte, defaultReqBodySzLim+1)),
+		want:    make([]byte, defaultReqBodySzLim),
 		wantErr: errReqLimitReached,
 	}, {
 		name:    "empty",