From 341393b1ebb9cafad9afdd50fc364f586e77d166 Mon Sep 17 00:00:00 2001
From: Martin Boehm <martin.boehm@1mbsoftware.net>
Date: Mon, 26 Mar 2018 15:17:44 +0200
Subject: [PATCH] Define error ErrBlockNotFound and implement it in btc

---
 bchain/coins/btc/bitcoinrpc.go | 20 ++++++++++++++++++++
 bchain/types.go                | 13 ++++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/bchain/coins/btc/bitcoinrpc.go b/bchain/coins/btc/bitcoinrpc.go
index a85f24ca..b9607472 100644
--- a/bchain/coins/btc/bitcoinrpc.go
+++ b/bchain/coins/btc/bitcoinrpc.go
@@ -331,6 +331,11 @@ func (b *BitcoinRPC) GetBlockChainInfo() (string, error) {
 	return res.Result.Chain, nil
 }
 
+func isErrBlockNotFound(err error) bool {
+	return err.Error() == "Block not found" ||
+		err.Error() == "Block height out of range"
+}
+
 // GetBlockHash returns hash of block in best-block-chain at given height.
 func (b *BitcoinRPC) GetBlockHash(height uint32) (string, error) {
 	glog.V(1).Info("rpc: getblockhash ", height)
@@ -344,6 +349,9 @@ func (b *BitcoinRPC) GetBlockHash(height uint32) (string, error) {
 		return "", errors.Annotatef(err, "height %v", height)
 	}
 	if res.Error != nil {
+		if isErrBlockNotFound(res.Error) {
+			return "", bchain.ErrBlockNotFound
+		}
 		return "", errors.Annotatef(res.Error, "height %v", height)
 	}
 	return res.Result, nil
@@ -363,6 +371,9 @@ func (b *BitcoinRPC) GetBlockHeader(hash string) (*bchain.BlockHeader, error) {
 		return nil, errors.Annotatef(err, "hash %v", hash)
 	}
 	if res.Error != nil {
+		if isErrBlockNotFound(res.Error) {
+			return nil, bchain.ErrBlockNotFound
+		}
 		return nil, errors.Annotatef(res.Error, "hash %v", hash)
 	}
 	return &res.Result, nil
@@ -423,6 +434,9 @@ func (b *BitcoinRPC) GetBlockRaw(hash string) ([]byte, error) {
 		return nil, errors.Annotatef(err, "hash %v", hash)
 	}
 	if res.Error != nil {
+		if isErrBlockNotFound(res.Error) {
+			return nil, bchain.ErrBlockNotFound
+		}
 		return nil, errors.Annotatef(res.Error, "hash %v", hash)
 	}
 	return hex.DecodeString(res.Result)
@@ -443,6 +457,9 @@ func (b *BitcoinRPC) GetBlockList(hash string) (*bchain.Block, error) {
 		return nil, errors.Annotatef(err, "hash %v", hash)
 	}
 	if res.Error != nil {
+		if isErrBlockNotFound(res.Error) {
+			return nil, bchain.ErrBlockNotFound
+		}
 		return nil, errors.Annotatef(res.Error, "hash %v", hash)
 	}
 
@@ -475,6 +492,9 @@ func (b *BitcoinRPC) GetBlockFull(hash string) (*bchain.Block, error) {
 		return nil, errors.Annotatef(err, "hash %v", hash)
 	}
 	if res.Error != nil {
+		if isErrBlockNotFound(res.Error) {
+			return nil, bchain.ErrBlockNotFound
+		}
 		return nil, errors.Annotatef(res.Error, "hash %v", hash)
 	}
 	return &res.Result, nil
diff --git a/bchain/types.go b/bchain/types.go
index 64a72a2c..e482ee39 100644
--- a/bchain/types.go
+++ b/bchain/types.go
@@ -1,6 +1,17 @@
 package bchain
 
-import "fmt"
+import (
+	"errors"
+	"fmt"
+)
+
+// errors with specific meaning returned by blockchain rpc
+var (
+	// ErrBlockNotFound is returned when block is not found
+	// either unknown hash or too high height
+	// can be returned from GetBlockHash, GetBlockHeader, GetBlock
+	ErrBlockNotFound = errors.New("Block not found")
+)
 
 type ScriptSig struct {
 	// Asm string `json:"asm"`