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lib/protocol: Use constants instead of init time hashing (fixes #5624) (#5625) 

This constructs the map of hashes of zero blocks from constants instead
of calculating it at startup time. A new test verifies that the map is
correct.
This commit is contained in:
Jakob Borg 2019-03-27 20:20:30 +01:00 committed by GitHub
parent 8d1eff7e41
commit bf3834e367
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 24 additions and 2 deletions
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15
lib/protocol/protocol.go
View File

@ -41,12 +41,23 @@ const (
var BlockSizes []int
// For each block size, the hash of a block of all zeroes
var sha256OfEmptyBlock = make(map[int][sha256.Size]byte)
var sha256OfEmptyBlock = map[int][sha256.Size]byte{
128 << KiB: {0xfa, 0x43, 0x23, 0x9b, 0xce, 0xe7, 0xb9, 0x7c, 0xa6, 0x2f, 0x0, 0x7c, 0xc6, 0x84, 0x87, 0x56, 0xa, 0x39, 0xe1, 0x9f, 0x74, 0xf3, 0xdd, 0xe7, 0x48, 0x6d, 0xb3, 0xf9, 0x8d, 0xf8, 0xe4, 0x71},
256 << KiB: {0x8a, 0x39, 0xd2, 0xab, 0xd3, 0x99, 0x9a, 0xb7, 0x3c, 0x34, 0xdb, 0x24, 0x76, 0x84, 0x9c, 0xdd, 0xf3, 0x3, 0xce, 0x38, 0x9b, 0x35, 0x82, 0x68, 0x50, 0xf9, 0xa7, 0x0, 0x58, 0x9b, 0x4a, 0x90},
512 << KiB: {0x7, 0x85, 0x4d, 0x2f, 0xef, 0x29, 0x7a, 0x6, 0xba, 0x81, 0x68, 0x5e, 0x66, 0xc, 0x33, 0x2d, 0xe3, 0x6d, 0x5d, 0x18, 0xd5, 0x46, 0x92, 0x7d, 0x30, 0xda, 0xad, 0x6d, 0x7f, 0xda, 0x15, 0x41},
1 << MiB: {0x30, 0xe1, 0x49, 0x55, 0xeb, 0xf1, 0x35, 0x22, 0x66, 0xdc, 0x2f, 0xf8, 0x6, 0x7e, 0x68, 0x10, 0x46, 0x7, 0xe7, 0x50, 0xab, 0xb9, 0xd3, 0xb3, 0x65, 0x82, 0xb8, 0xaf, 0x90, 0x9f, 0xcb, 0x58},
2 << MiB: {0x56, 0x47, 0xf0, 0x5e, 0xc1, 0x89, 0x58, 0x94, 0x7d, 0x32, 0x87, 0x4e, 0xeb, 0x78, 0x8f, 0xa3, 0x96, 0xa0, 0x5d, 0xb, 0xab, 0x7c, 0x1b, 0x71, 0xf1, 0x12, 0xce, 0xb7, 0xe9, 0xb3, 0x1e, 0xee},
4 << MiB: {0xbb, 0x9f, 0x8d, 0xf6, 0x14, 0x74, 0xd2, 0x5e, 0x71, 0xfa, 0x0, 0x72, 0x23, 0x18, 0xcd, 0x38, 0x73, 0x96, 0xca, 0x17, 0x36, 0x60, 0x5e, 0x12, 0x48, 0x82, 0x1c, 0xc0, 0xde, 0x3d, 0x3a, 0xf8},
8 << MiB: {0x2d, 0xae, 0xb1, 0xf3, 0x60, 0x95, 0xb4, 0x4b, 0x31, 0x84, 0x10, 0xb3, 0xf4, 0xe8, 0xb5, 0xd9, 0x89, 0xdc, 0xc7, 0xbb, 0x2, 0x3d, 0x14, 0x26, 0xc4, 0x92, 0xda, 0xb0, 0xa3, 0x5, 0x3e, 0x74},
16 << MiB: {0x8, 0xa, 0xcf, 0x35, 0xa5, 0x7, 0xac, 0x98, 0x49, 0xcf, 0xcb, 0xa4, 0x7d, 0xc2, 0xad, 0x83, 0xe0, 0x1b, 0x75, 0x66, 0x3a, 0x51, 0x62, 0x79, 0xc8, 0xb9, 0xd2, 0x43, 0xb7, 0x19, 0x64, 0x3e},
}
func init() {
for blockSize := MinBlockSize; blockSize <= MaxBlockSize; blockSize *= 2 {
BlockSizes = append(BlockSizes, blockSize)
sha256OfEmptyBlock[blockSize] = sha256.Sum256(make([]byte, blockSize))
if _, ok := sha256OfEmptyBlock[blockSize]; !ok {
panic("missing hard coded value for sha256 of empty block")
}
}
BufferPool = newBufferPool()
}

11
lib/protocol/protocol_test.go
View File

@ -4,6 +4,7 @@ package protocol
import (
"bytes"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"errors"
@ -610,3 +611,13 @@ func TestIsEquivalent(t *testing.T) {
}
}
}
func TestSha256OfEmptyBlock(t *testing.T) {
// every block size should have a correct entry in sha256OfEmptyBlock
for blockSize := MinBlockSize; blockSize <= MaxBlockSize; blockSize *= 2 {
expected := sha256.Sum256(make([]byte, blockSize))
if sha256OfEmptyBlock[blockSize] != expected {
t.Error("missing or wrong hash for block of size", blockSize)
}
}
}