Add /send restrictions and return correct error codes (#1156)

* Add /send restrictions and return correct error codes

- Max 50 PDUs / 100 EDUs
- Fail the transaction when PDUs contain bad JSON

* Update whitelist

* Unbreak test

* Linting

federationapi/routing/send.go

@@ -61,6 +61,14 @@ func Send(
 			JSON: jsonerror.NotJSON("The request body could not be decoded into valid JSON. " + err.Error()),
 		}
 	}
+	// Transactions are limited in size; they can have at most 50 PDUs and 100 EDUs.
+	// https://matrix.org/docs/spec/server_server/latest#transactions
+	if len(txnEvents.PDUs) > 50 || len(txnEvents.EDUs) > 100 {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("max 50 pdus / 100 edus"),
+		}
+	}
 
 	// TODO: Really we should have a function to convert FederationRequest to txnReq
 	t.PDUs = txnEvents.PDUs
@@ -71,10 +79,10 @@ func Send(
 
 	util.GetLogger(httpReq.Context()).Infof("Received transaction %q containing %d PDUs, %d EDUs", txnID, len(t.PDUs), len(t.EDUs))
 
-	resp, err := t.processTransaction()
+	resp, jsonErr := t.processTransaction()
-	if err != nil {
+	if jsonErr != nil {
-		util.GetLogger(httpReq.Context()).WithError(err).Error("t.processTransaction failed")
+		util.GetLogger(httpReq.Context()).WithField("jsonErr", jsonErr).Error("t.processTransaction failed")
-		return util.ErrorResponse(err)
+		return *jsonErr
 	}
 
 	// https://matrix.org/docs/spec/server_server/r0.1.3#put-matrix-federation-v1-send-txnid
@@ -112,7 +120,7 @@ type txnFederationClient interface {
 		roomVersion gomatrixserverlib.RoomVersion) (res gomatrixserverlib.RespMissingEvents, err error)
 }
 
-func (t *txnReq) processTransaction() (*gomatrixserverlib.RespSend, error) {
+func (t *txnReq) processTransaction() (*gomatrixserverlib.RespSend, *util.JSONResponse) {
 	results := make(map[string]gomatrixserverlib.PDUResult)
 
 	pdus := []gomatrixserverlib.HeaderedEvent{}
@@ -136,10 +144,20 @@ func (t *txnReq) processTransaction() (*gomatrixserverlib.RespSend, error) {
 		}
 		event, err := gomatrixserverlib.NewEventFromUntrustedJSON(pdu, verRes.RoomVersion)
 		if err != nil {
-			util.GetLogger(t.context).WithError(err).Warnf("Transaction: Failed to parse event JSON of event %q", event.EventID())
+			if _, ok := err.(gomatrixserverlib.BadJSONError); ok {
-			results[event.EventID()] = gomatrixserverlib.PDUResult{
+				// Room version 6 states that homeservers should strictly enforce canonical JSON
-				Error: err.Error(),
+				// on PDUs.
+				//
+				// This enforces that the entire transaction is rejected if a single bad PDU is
+				// sent. It is unclear if this is the correct behaviour or not.
+				//
+				// See https://github.com/matrix-org/synapse/issues/7543
+				return nil, &util.JSONResponse{
+					Code: 400,
+					JSON: jsonerror.BadJSON("PDU contains bad JSON"),
+				}
 			}
+			util.GetLogger(t.context).WithError(err).Warnf("Transaction: Failed to parse event JSON of event %s", string(pdu))
 			continue
 		}
 		if err = gomatrixserverlib.VerifyAllEventSignatures(t.context, []gomatrixserverlib.Event{event}, t.keys); err != nil {
@@ -174,7 +192,8 @@ func (t *txnReq) processTransaction() (*gomatrixserverlib.RespSend, error) {
 				// Any other error should be the result of a temporary error in
 				// our server so we should bail processing the transaction entirely.
 				util.GetLogger(t.context).Warnf("Processing %s failed fatally: %s", e.EventID(), err)
-				return nil, err
+				jsonErr := util.ErrorResponse(err)
+				return nil, &jsonErr
 			} else {
 				// Auth errors mean the event is 'rejected' which have to be silent to appease sytest
 				_, rejected := err.(*gomatrixserverlib.NotAllowed)

federationapi/routing/send_test.go

@@ -337,7 +337,7 @@ func mustCreateTransaction(rsAPI api.RoomserverInternalAPI, fedClient txnFederat
 func mustProcessTransaction(t *testing.T, txn *txnReq, pdusWithErrors []string) {
 	res, err := txn.processTransaction()
 	if err != nil {
-		t.Errorf("txn.processTransaction returned an error: %s", err)
+		t.Errorf("txn.processTransaction returned an error: %v", err)
 		return
 	}
 	if len(res.PDUs) != len(txn.PDUs) {

go.mod

@@ -20,7 +20,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200518170932-783164aeeda4
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200522092705-bc8506ccbcf3
 	github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20200617141855-5539854e4abc
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20200623103809-13ff8109e137
 	github.com/matrix-org/naffka v0.0.0-20200422140631-181f1ee7401f
 	github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7
 	github.com/mattn/go-sqlite3 v2.0.2+incompatible
@@ -38,7 +38,6 @@ require (
 	github.com/yggdrasil-network/yggdrasil-go v0.3.15-0.20200530233943-aec82d7a391b
 	go.uber.org/atomic v1.4.0
 	golang.org/x/crypto v0.0.0-20200221231518-2aa609cf4a9d
-	golang.org/x/mobile v0.0.0-20200329125638-4c31acba0007 // indirect
 	gopkg.in/h2non/bimg.v1 v1.0.18
 	gopkg.in/yaml.v2 v2.2.8
 )

go.sum

@@ -4,7 +4,6 @@ github.com/AndreasBriese/bbloom v0.0.0-20190306092124-e2d15f34fcf9/go.mod h1:bOv
 github.com/Arceliar/phony v0.0.0-20191006174943-d0c68492aca0 h1:p3puK8Sl2xK+2FnnIvY/C0N1aqJo2kbEsdAzU+Tnv48=
 github.com/Arceliar/phony v0.0.0-20191006174943-d0c68492aca0/go.mod h1:6Lkn+/zJilRMsKmbmG1RPoamiArC6HS73xbwRyp3UyI=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
-github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/Kubuxu/go-os-helper v0.0.1/go.mod h1:N8B+I7vPCT80IcP58r50u4+gEEcsZETFUpAzWW2ep1Y=
 github.com/Shopify/sarama v1.26.1 h1:3jnfWKD7gVwbB1KSy/lE0szA9duPuSFLViK0o/d3DgA=
 github.com/Shopify/sarama v1.26.1/go.mod h1:NbSGBSSndYaIhRcBtY9V0U7AyH+x71bG668AuWys/yU=
@@ -372,10 +371,8 @@ github.com/matrix-org/go-sqlite3-js v0.0.0-20200522092705-bc8506ccbcf3 h1:Yb+Wlf
 github.com/matrix-org/go-sqlite3-js v0.0.0-20200522092705-bc8506ccbcf3/go.mod h1:e+cg2q7C7yE5QnAXgzo512tgFh1RbQLC0+jozuegKgo=
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26 h1:Hr3zjRsq2bhrnp3Ky1qgx/fzCtCALOoGYylh2tpS9K4=
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26/go.mod h1:3fxX6gUjWyI/2Bt7J1OLhpCzOfO/bB3AiX0cJtEKud0=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200616150727-7ac22b6f8e65 h1:2CcCcBnWdDPDOqFKiGOM+mi/KDDZXSTKmvFy/0/+ZJI=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200623103809-13ff8109e137 h1:+eBh4L04+08IslvFM071TNrQTggU317GsQKzZ1SGEVo=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200616150727-7ac22b6f8e65/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200623103809-13ff8109e137/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200617141855-5539854e4abc h1:Oxidxr/H1Nh8aOFWAhTzQYLDOc9OuoJwfDjgEHpyqNE=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200617141855-5539854e4abc/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
 github.com/matrix-org/naffka v0.0.0-20200422140631-181f1ee7401f h1:pRz4VTiRCO4zPlEMc3ESdUOcW4PXHH4Kj+YDz1XyE+Y=
 github.com/matrix-org/naffka v0.0.0-20200422140631-181f1ee7401f/go.mod h1:y0oDTjZDv5SM9a2rp3bl+CU+bvTRINQsdb7YlDql5Go=
 github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7 h1:ntrLa/8xVzeSs8vHFHK25k0C+NV74sYMJnNSg5NoSRo=
@@ -590,7 +587,6 @@ golang.org/x/crypto v0.0.0-20190225124518-7f87c0fbb88b/go.mod h1:6SG95UA2DQfeDnf
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190426145343-a29dc8fdc734/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20190611184440-5c40567a22f8/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20190618222545-ea8f1a30c443/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
@@ -601,18 +597,9 @@ golang.org/x/crypto v0.0.0-20200204104054-c9f3fb736b72/go.mod h1:LzIPMQfyMNhhGPh
 golang.org/x/crypto v0.0.0-20200221231518-2aa609cf4a9d h1:1ZiEyfaQIg3Qh0EoqpwAakHVhecoE5wlSg5GjnafJGw=
 golang.org/x/crypto v0.0.0-20200221231518-2aa609cf4a9d/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
-golang.org/x/exp v0.0.0-20190731235908-ec7cb31e5a56/go.mod h1:JhuoJpWY28nO4Vef9tZUw9qufEGTyX1+7lmHxV5q5G4=
-golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
-golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/lint v0.0.0-20190227174305-5b3e6a55c961/go.mod h1:wehouNa3lNwaWXcvxsM5YxQ5yQlVC4a0KAMCusXpPoU=
 golang.org/x/lint v0.0.0-20190313153728-d0100b6bd8b3/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
-golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
-golang.org/x/mobile v0.0.0-20200329125638-4c31acba0007 h1:JxsyO7zPDWn1rBZW8FV5RFwCKqYeXnyaS/VQPLpXu6I=
-golang.org/x/mobile v0.0.0-20200329125638-4c31acba0007/go.mod h1:skQtrUTUwhdJvXM/2KKJzY8pDgNr9I/FOMqDVRPBUS4=
-golang.org/x/mod v0.1.0/go.mod h1:0QHyrYULN0/3qlju5TqG8bIK38QM8yzMo5ekMj3DlcY=
-golang.org/x/mod v0.1.1-0.20191105210325-c90efee705ee/go.mod h1:QqPTAvyqsEbceGzBzNggFXnrqF1CaUcvgkdR5Ot7KZg=
-golang.org/x/mod v0.1.1-0.20191209134235-331c550502dd/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -682,10 +669,6 @@ golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd h1:/e+gpKk9r3dJobndpTytxS2gOy6m5uvpg+ISQoEcusQ=
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
-golang.org/x/tools v0.0.0-20190312151545-0bb0c0a6e846/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
-golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.0.0-20200117012304-6edc0a871e69 h1:yBHHx+XZqXJBm6Exke3N7V9gnlsyXxoCPEb1yVenjfk=
-golang.org/x/tools v0.0.0-20200117012304-6edc0a871e69/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=

sytest-whitelist

@@ -317,6 +317,8 @@ Invalid JSON integers
 Invalid JSON special values
 Invalid JSON floats
 Outbound federation will ignore a missing event with bad JSON for room version 6
+Server correctly handles transactions that break edu limits
+Server rejects invalid JSON in a version 6 room
 Can download without a file name over federation
 POST /media/r0/upload can create an upload
 GET /media/r0/download can fetch the value again