From 14a1da417fff2540f5b8df781df04526af6e208b Mon Sep 17 00:00:00 2001
From: Dave Collins <davec@conformal.com>
Date: Thu, 16 May 2013 09:07:04 -0500
Subject: [PATCH] Enforce max block payload size of 1MB.
This commit changes MsgBlock to enforce a 1MB max payload per the spec.
Previously it was only limited to the max overall message size. While
here, also enforce max payloads per message type (instead of only the max
overall message payload) when writing messages.
---
fakemessage_test.go | 13 ++++++++++---
message.go | 15 +++++++++++++--
message_test.go | 16 ++++++++++++----
msgblock.go | 7 +++++--
msgblock_test.go | 2 +-
test_coverage.txt | 4 ++--
6 files changed, 43 insertions(+), 14 deletions(-)
diff --git a/fakemessage_test.go b/fakemessage_test.go
index 36eac01a..c1676ee9 100644
--- a/fakemessage_test.go
+++ b/fakemessage_test.go
@@ -15,6 +15,7 @@ type fakeMessage struct {
command string
payload []byte
forceEncodeErr bool
+ forceLenErr bool
}
// BtcDecode doesn't do anything. It just satisfies the btcwire.Message
@@ -45,8 +46,14 @@ func (msg *fakeMessage) Command() string {
return msg.command
}
-// MaxPayloadLength simply returns 0. It is only here to satisfy the
-// btcwire.Message interface.
+// MaxPayloadLength returns the length of the payload field of fake message
+// or a smaller value if the forceLenErr flag of the fake message is set. It
+// satisfies the btcwire.Message interface.
func (msg *fakeMessage) MaxPayloadLength(pver uint32) uint32 {
- return 0
+ lenp := uint32(len(msg.payload))
+ if msg.forceLenErr {
+ return lenp - 1
+ }
+
+ return lenp
}
diff --git a/message.go b/message.go
index 80b748a9..06c65f1a 100644
--- a/message.go
+++ b/message.go
@@ -15,7 +15,7 @@ import (
// header. Shorter commands must be zero padded.
const commandSize = 12
-// maxMessagePayload is the maximum byes a message can be regardless of other
+// maxMessagePayload is the maximum bytes a message can be regardless of other
// individual limits imposed by messages themselves.
const maxMessagePayload = (1024 * 1024 * 32) // 32MB
@@ -158,6 +158,7 @@ func discardInput(r io.Reader, n uint32) {
func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet BitcoinNet) error {
var command [commandSize]byte
+ // Enforce max command size.
cmd := msg.Command()
if len(cmd) > commandSize {
str := fmt.Sprintf("command [%s] is too long [max %v]",
@@ -166,6 +167,7 @@ func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet BitcoinNet) erro
}
copy(command[:], []byte(cmd))
+ // Encode the message payload.
var bw bytes.Buffer
err := msg.BtcEncode(&bw, pver)
if err != nil {
@@ -174,7 +176,7 @@ func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet BitcoinNet) erro
payload := bw.Bytes()
lenp := len(payload)
- // Enforce maximum message payload.
+ // Enforce maximum overall message payload.
if lenp > maxMessagePayload {
str := fmt.Sprintf("message payload is too large - encoded "+
"%d bytes, but maximum message payload is %d bytes",
@@ -182,6 +184,15 @@ func WriteMessage(w io.Writer, msg Message, pver uint32, btcnet BitcoinNet) erro
return messageError("WriteMessage", str)
}
+ // Enforce maximum message payload based on the message type.
+ mpl := msg.MaxPayloadLength(pver)
+ if uint32(lenp) > mpl {
+ str := fmt.Sprintf("message payload is too large - encoded "+
+ "%d bytes, but maximum message payload size for "+
+ "messages of type [%s] is %d.", lenp, cmd, mpl)
+ return messageError("WriteMessage", str)
+ }
+
// Create header for the message.
hdr := messageHeader{}
hdr.magic = btcnet
diff --git a/message_test.go b/message_test.go
index e3483fc2..9186bdbd 100644
--- a/message_test.go
+++ b/message_test.go
@@ -317,10 +317,16 @@ func TestWriteMessageWireErrors(t *testing.T) {
// Fake message with a problem during encoding
encodeErrMsg := &fakeMessage{forceEncodeErr: true}
- // Fake message that has a payload which exceed max.
- exceedPayload := make([]byte, btcwire.MaxMessagePayload+1)
- exceedPayloadErrMsg := &fakeMessage{payload: exceedPayload}
+ // Fake message that has payload which exceeds max overall message size.
+ exceedOverallPayload := make([]byte, btcwire.MaxMessagePayload+1)
+ exceedOverallPayloadErrMsg := &fakeMessage{payload: exceedOverallPayload}
+ // Fake message that has payload which exceeds max allowed per message.
+ exceedPayload := make([]byte, 1)
+ exceedPayloadErrMsg := &fakeMessage{payload: exceedPayload, forceLenErr: true}
+
+ // Fake message that is used to force errors in the header and payload
+ // writes.
bogusPayload := []byte{0x01, 0x02, 0x03, 0x04}
bogusMsg := &fakeMessage{command: "bogus", payload: bogusPayload}
@@ -335,7 +341,9 @@ func TestWriteMessageWireErrors(t *testing.T) {
{badCommandMsg, pver, btcnet, 0, btcwireErr},
// Force error in payload encode.
{encodeErrMsg, pver, btcnet, 0, btcwireErr},
- // Force error due to exceeding max payload size.
+ // Force error due to exceeding max overall message payload size.
+ {exceedOverallPayloadErrMsg, pver, btcnet, 0, btcwireErr},
+ // Force error due to exceeding max payload for message type.
{exceedPayloadErrMsg, pver, btcnet, 0, btcwireErr},
// Force error in header write.
{bogusMsg, pver, btcnet, 0, io.ErrShortWrite},
diff --git a/msgblock.go b/msgblock.go
index b87496c2..e3ecc488 100644
--- a/msgblock.go
+++ b/msgblock.go
@@ -12,6 +12,9 @@ import (
// MaxBlocksPerMsg is the maximum number of blocks allowed per message.
const MaxBlocksPerMsg = 500
+// maxBlockPayload is the maximum bytes a block message can be.
+const maxBlockPayload = (1024 * 1024) // 1MB
+
// TxLoc holds locator data for the offset and length of where a transaction is
// located within a MsgBlock data buffer.
type TxLoc struct {
@@ -131,8 +134,8 @@ func (msg *MsgBlock) Command() string {
// receiver. This is part of the Message interface implementation.
func (msg *MsgBlock) MaxPayloadLength(pver uint32) uint32 {
// Block header at 81 bytes + max transactions which can vary up to the
- // max message payload.
- return maxMessagePayload
+ // maxBlockPayload (including the block header).
+ return maxBlockPayload
}
// BlockSha computes the block identifier hash for this block.
diff --git a/msgblock_test.go b/msgblock_test.go
index bd5082a5..780a657e 100644
--- a/msgblock_test.go
+++ b/msgblock_test.go
@@ -35,7 +35,7 @@ func TestBlock(t *testing.T) {
// Ensure max payload is expected value for latest protocol version.
// Num addresses (varInt) + max allowed addresses.
- wantPayload := uint32(1024 * 1024 * 32)
+ wantPayload := uint32(1024 * 1024)
maxPayload := msg.MaxPayloadLength(pver)
if maxPayload != wantPayload {
t.Errorf("MaxPayloadLength: wrong max payload length for "+
diff --git a/test_coverage.txt b/test_coverage.txt
index 69c5b942..fce68621 100644
--- a/test_coverage.txt
+++ b/test_coverage.txt
@@ -1,6 +1,6 @@
github.com/conformal/btcwire/message.go ReadMessage 100.00% (37/37)
-github.com/conformal/btcwire/message.go WriteMessage 100.00% (27/27)
+github.com/conformal/btcwire/message.go WriteMessage 100.00% (31/31)
github.com/conformal/btcwire/msgtx.go MsgTx.BtcDecode 100.00% (25/25)
github.com/conformal/btcwire/msgversion.go MsgVersion.BtcDecode 100.00% (25/25)
github.com/conformal/btcwire/msgtx.go MsgTx.Copy 100.00% (24/24)
@@ -149,5 +149,5 @@ github.com/conformal/btcwire/msgversion.go NewMsgVersion 100.00% (1/1)
github.com/conformal/btcwire/netaddress.go NetAddress.AddService 100.00% (1/1)
github.com/conformal/btcwire/shahash.go ShaHash.IsEqual 100.00% (1/1)
github.com/conformal/btcwire/invvect.go NewInvVect 100.00% (1/1)
-github.com/conformal/btcwire --------------------------------- 100.00% (923/923)
+github.com/conformal/btcwire --------------------------------- 100.00% (927/927)