From 26c9134f356b2ba1fe512fb9812ff1a87529fb7e Mon Sep 17 00:00:00 2001
From: Anton Kaliaev <anton.kalyaev@gmail.com>
Date: Mon, 20 Apr 2020 09:56:18 +0400
Subject: [PATCH] lite2: verify ConsensusHash in rpc client

______

For contributor use:

- [ ] Wrote tests
- [ ] Updated CHANGELOG_PENDING.md
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Updated relevant documentation (`docs/`) and code comments
- [x] Re-reviewed `Files changed` in the Github PR explorer
---
 lite2/rpc/client.go | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/lite2/rpc/client.go b/lite2/rpc/client.go
index abd15adc2..da42a747a 100644
--- a/lite2/rpc/client.go
+++ b/lite2/rpc/client.go
@@ -156,7 +156,24 @@ func (c *Client) ConsensusState() (*ctypes.ResultConsensusState, error) {
 }
 
 func (c *Client) ConsensusParams(height *int64) (*ctypes.ResultConsensusParams, error) {
-	return c.next.ConsensusParams(height)
+	res, err := c.next.ConsensusParams(height)
+	if err != nil {
+		return nil, err
+	}
+
+	// Update the light client if we're behind.
+	h, err := c.updateLiteClientIfNeededTo(res.BlockHeight)
+	if err != nil {
+		return nil, err
+	}
+
+	// Verify hash.
+	if cH, tH := res.ConsensusParams.Hash(), h.ConsensusHash; !bytes.Equal(cH, tH) {
+		return nil, fmt.Errorf("params hash %X does not match trusted hash %X",
+			cH, tH)
+	}
+
+	return res, nil
 }
 
 func (c *Client) Health() (*ctypes.ResultHealth, error) {