feat: initial goget release — modern IPv6-first download utility

internal/crypto/checksum.go

@@ -0,0 +1,150 @@
+//go:build linux || freebsd
+// +build linux freebsd
+
+package crypto
+
+import (
+	"crypto/sha256"
+	"crypto/sha512"
+	"encoding/hex"
+	"fmt"
+	"hash"
+	"io"
+	"os"
+
+	"golang.org/x/crypto/blake2b"
+	"golang.org/x/crypto/sha3"
+)
+
+// ChecksumType defines the checksum type
+type ChecksumType string
+
+const (
+	SHA256   ChecksumType = "sha256"
+	SHA512   ChecksumType = "sha512"
+	BLAKE2b  ChecksumType = "blake2b"
+	SHA3_256 ChecksumType = "sha3-256"
+	SHA3_512 ChecksumType = "sha3-512"
+	MD5      ChecksumType = "md5"
+)
+
+// ChecksumVerifier verifies a file checksum
+type ChecksumVerifier struct {
+	hashType ChecksumType
+	hasher   hash.Hash
+	expected string
+}
+
+// NewChecksumVerifier creates new verifier
+func NewChecksumVerifier(hashType ChecksumType, expected string) (*ChecksumVerifier, error) {
+	var hasher hash.Hash
+
+	switch hashType {
+	case SHA256:
+		hasher = sha256.New()
+	case SHA512:
+		hasher = sha512.New()
+	case BLAKE2b:
+		h, err := blake2b.New256(nil)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create blake2b hasher: %w", err)
+		}
+		hasher = h
+	case SHA3_256:
+		hasher = sha3.New256()
+	case SHA3_512:
+		hasher = sha3.New512()
+	case MD5:
+		return nil, fmt.Errorf("md5 is deprecated and not supported")
+	default:
+		return nil, fmt.Errorf("unsupported hash type: %s", hashType)
+	}
+
+	return &ChecksumVerifier{
+		hashType: hashType,
+		hasher:   hasher,
+		expected: expected,
+	}, nil
+}
+
+// VerifyFile verifies the checksum of a file
+func (cv *ChecksumVerifier) VerifyFile(path string) (bool, string, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return false, "", fmt.Errorf("failed to open file: %w", err)
+	}
+	defer file.Close()
+
+	cv.hasher.Reset()
+	_, err = io.Copy(cv.hasher, file)
+	if err != nil {
+		return false, "", fmt.Errorf("failed to read file: %w", err)
+	}
+
+	actual := hex.EncodeToString(cv.hasher.Sum(nil))
+	match := actual == cv.expected
+
+	return match, actual, nil
+}
+
+// VerifyReader verifies checksum from a reader (streaming)
+func (cv *ChecksumVerifier) VerifyReader(r io.Reader) (string, error) {
+	cv.hasher.Reset()
+	_, err := io.Copy(cv.hasher, r)
+	if err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(cv.hasher.Sum(nil)), nil
+}
+
+// Hasher returns the underlying hasher for streaming verification
+func (cv *ChecksumVerifier) Hasher() hash.Hash {
+	return cv.hasher
+}
+
+// Expected returns the expected checksum
+func (cv *ChecksumVerifier) Expected() string {
+	return cv.expected
+}
+
+// Type returns the hash function type
+func (cv *ChecksumVerifier) Type() ChecksumType {
+	return cv.hashType
+}
+
+// ComputeFileChecksum calculates the checksum of a file
+func ComputeFileChecksum(path string, hashType ChecksumType) (string, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	var hasher hash.Hash
+	switch hashType {
+	case SHA256:
+		hasher = sha256.New()
+	case SHA512:
+		hasher = sha512.New()
+	case BLAKE2b:
+		h, err := blake2b.New256(nil)
+		if err != nil {
+			return "", fmt.Errorf("failed to create blake2b hasher: %w", err)
+		}
+		hasher = h
+	case SHA3_256:
+		hasher = sha3.New256()
+	case SHA3_512:
+		hasher = sha3.New512()
+	default:
+		return "", fmt.Errorf("unsupported hash type: %s", hashType)
+	}
+
+	_, err = io.Copy(hasher, file)
+	if err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(hasher.Sum(nil)), nil
+}