From 8f463cf35ca0cdad6238871c3dd98ce4751a7631 Mon Sep 17 00:00:00 2001
From: Anton Kaliaev <anton.kalyaev@gmail.com>
Date: Tue, 28 Apr 2020 14:05:09 +0400
Subject: [PATCH] p2p: set RecvMessageCapacity to maxMsgSize in all reactors

to prevent malicious nodes from sending us large messages (~21MB, which
is the default `RecvMessageCapacity`)

This allows us to remove unnecessary `maxMsgSize` check in `decodeMsg`. Since each channel has a msg capacity set to `maxMsgSize`, there's no need to check it again in `decodeMsg`.

Closes #1503
---
 blockchain/v0/reactor.go |  3 ---
 blockchain/v1/reactor.go |  3 ---
 blockchain/v2/reactor.go |  3 ---
 consensus/reactor.go     |  3 ---
 evidence/reactor.go      |  4 +---
 mempool/reactor.go       | 10 ++++------
 p2p/pex/pex_reactor.go   | 10 ++++------
 7 files changed, 9 insertions(+), 27 deletions(-)

diff --git a/blockchain/v0/reactor.go b/blockchain/v0/reactor.go
index 247222160..c82457bee 100644
--- a/blockchain/v0/reactor.go
+++ b/blockchain/v0/reactor.go
@@ -394,9 +394,6 @@ func RegisterBlockchainMessages(cdc *amino.Codec) {
 }
 
 func decodeMsg(bz []byte) (msg BlockchainMessage, err error) {
-	if len(bz) > maxMsgSize {
-		return msg, fmt.Errorf("msg exceeds max size (%d > %d)", len(bz), maxMsgSize)
-	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
 }
diff --git a/blockchain/v1/reactor.go b/blockchain/v1/reactor.go
index 28a314b8a..315dbffbf 100644
--- a/blockchain/v1/reactor.go
+++ b/blockchain/v1/reactor.go
@@ -539,9 +539,6 @@ func RegisterBlockchainMessages(cdc *amino.Codec) {
 }
 
 func decodeMsg(bz []byte) (msg BlockchainMessage, err error) {
-	if len(bz) > maxMsgSize {
-		return msg, fmt.Errorf("msg exceeds max size (%d > %d)", len(bz), maxMsgSize)
-	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
 }
diff --git a/blockchain/v2/reactor.go b/blockchain/v2/reactor.go
index ff89ee94c..d68b27a41 100644
--- a/blockchain/v2/reactor.go
+++ b/blockchain/v2/reactor.go
@@ -453,9 +453,6 @@ func RegisterBlockchainMessages(cdc *amino.Codec) {
 }
 
 func decodeMsg(bz []byte) (msg BlockchainMessage, err error) {
-	if len(bz) > maxMsgSize {
-		return msg, fmt.Errorf("msg exceeds max size (%d > %d)", len(bz), maxMsgSize)
-	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
 }
diff --git a/consensus/reactor.go b/consensus/reactor.go
index c8c344ac8..99f40ac0b 100644
--- a/consensus/reactor.go
+++ b/consensus/reactor.go
@@ -1404,9 +1404,6 @@ func RegisterMessages(cdc *amino.Codec) {
 }
 
 func decodeMsg(bz []byte) (msg Message, err error) {
-	if len(bz) > maxMsgSize {
-		return msg, fmt.Errorf("msg exceeds max size (%d > %d)", len(bz), maxMsgSize)
-	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
 }
diff --git a/evidence/reactor.go b/evidence/reactor.go
index 8314fa0ef..2a9554707 100644
--- a/evidence/reactor.go
+++ b/evidence/reactor.go
@@ -51,6 +51,7 @@ func (evR *Reactor) GetChannels() []*p2p.ChannelDescriptor {
 		{
 			ID:       EvidenceChannel,
 			Priority: 5,
+			RecvMessageCapacity: maxMsgSize,
 		},
 	}
 }
@@ -235,9 +236,6 @@ func RegisterMessages(cdc *amino.Codec) {
 }
 
 func decodeMsg(bz []byte) (msg Message, err error) {
-	if len(bz) > maxMsgSize {
-		return msg, fmt.Errorf("msg exceeds max size (%d > %d)", len(bz), maxMsgSize)
-	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
 }
diff --git a/mempool/reactor.go b/mempool/reactor.go
index fda12c021..d64bb7868 100644
--- a/mempool/reactor.go
+++ b/mempool/reactor.go
@@ -137,10 +137,12 @@ func (memR *Reactor) OnStart() error {
 // GetChannels implements Reactor.
 // It returns the list of channels for this reactor.
 func (memR *Reactor) GetChannels() []*p2p.ChannelDescriptor {
+	maxMsgSize := calcMaxMsgSize(memR.config.MaxTxBytes)
 	return []*p2p.ChannelDescriptor{
 		{
-			ID:       MempoolChannel,
-			Priority: 5,
+			ID:                  MempoolChannel,
+			Priority:            5,
+			RecvMessageCapacity: maxMsgSize,
 		},
 	}
 }
@@ -271,10 +273,6 @@ func RegisterMessages(cdc *amino.Codec) {
 }
 
 func (memR *Reactor) decodeMsg(bz []byte) (msg Message, err error) {
-	maxMsgSize := calcMaxMsgSize(memR.config.MaxTxBytes)
-	if l := len(bz); l > maxMsgSize {
-		return msg, ErrTxTooLarge{maxMsgSize, l}
-	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
 }
diff --git a/p2p/pex/pex_reactor.go b/p2p/pex/pex_reactor.go
index d06814195..8bdb0d77f 100644
--- a/p2p/pex/pex_reactor.go
+++ b/p2p/pex/pex_reactor.go
@@ -180,9 +180,10 @@ func (r *Reactor) OnStop() {
 func (r *Reactor) GetChannels() []*conn.ChannelDescriptor {
 	return []*conn.ChannelDescriptor{
 		{
-			ID:                PexChannel,
-			Priority:          1,
-			SendQueueCapacity: 10,
+			ID:                  PexChannel,
+			Priority:            1,
+			SendQueueCapacity:   10,
+			RecvMessageCapacity: maxMsgSize,
 		},
 	}
 }
@@ -771,9 +772,6 @@ func RegisterMessages(cdc *amino.Codec) {
 }
 
 func decodeMsg(bz []byte) (msg Message, err error) {
-	if len(bz) > maxMsgSize {
-		return msg, fmt.Errorf("msg exceeds max size (%d > %d)", len(bz), maxMsgSize)
-	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
 }