92 lines
2.2 KiB
Go
92 lines
2.2 KiB
Go
package jcstypes
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import (
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"strings"
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)
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// 文件的哈希值，格式：[前缀: 4个字符][哈希值: 64个字符]
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// 前缀用于区分哈希值的类型：
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//
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// - "Full"：完整文件的哈希值
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//
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// - "Comp"：将文件拆分成多个分片，每一个分片计算Hash之后再合并的哈希值
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//
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// 哈希值：SHA256哈希值，全大写的16进制字符串格式
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type FileHash string
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const (
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FullHashPrefix = "Full"
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CompositeHashPrefix = "Comp"
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EmptyHash = FileHash("Full0000000000000000000000000000000000000000000000000000000000000000")
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)
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func (h *FileHash) GetPrefix() string {
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return string((*h)[:4])
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}
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func (h *FileHash) GetHash() string {
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return string((*h)[4:])
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}
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// 由调用者保证Hash值有效
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func (h *FileHash) GetHashBytes() []byte {
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bytes, _ := hex.DecodeString(h.GetHash())
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return bytes
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}
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func (h *FileHash) GetHashPrefix(len int) string {
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return string((*h)[4 : 4+len])
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}
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func (h *FileHash) IsFullHash() bool {
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return (*h)[:4] == FullHashPrefix
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}
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func (h *FileHash) IsCompositeHash() bool {
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return (*h)[:4] == CompositeHashPrefix
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}
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func ParseHash(hashStr string) (FileHash, error) {
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if len(hashStr) != 4+64 {
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return "", fmt.Errorf("hash string length should be 4+64, but got %d", len(hashStr))
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}
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prefix := hashStr[:4]
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hash := hashStr[4:]
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if prefix != FullHashPrefix && prefix != CompositeHashPrefix {
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return "", fmt.Errorf("invalid hash prefix: %s", prefix)
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}
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if len(hash) != 64 {
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return "", fmt.Errorf("invalid hash length: %d", len(hash))
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}
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for _, c := range hash {
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if (c < '0' || c > '9') && (c < 'A' || c > 'F') {
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return "", fmt.Errorf("invalid hash character: %c", c)
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}
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}
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return FileHash(hashStr), nil
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}
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func NewFullHash(hash []byte) FileHash {
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return FileHash(FullHashPrefix + strings.ToUpper(hex.EncodeToString(hash)))
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}
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func NewFullHashFromString(hashStr string) FileHash {
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return FileHash(FullHashPrefix + strings.ToUpper(hashStr))
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}
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func CalculateCompositeHash(segmentHashes [][]byte) FileHash {
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data := make([]byte, len(segmentHashes)*32)
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for i, segmentHash := range segmentHashes {
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copy(data[i*32:], segmentHash)
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}
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hash := sha256.Sum256(data)
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return FileHash(CompositeHashPrefix + strings.ToUpper(hex.EncodeToString(hash[:])))
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}
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