depot/go/nix/nar/narinfo/narinfo.go

384 lines
8.6 KiB
Go

// SPDX-FileCopyrightText: 2020 Luke Granger-Brown <depot@lukegb.com>
//
// SPDX-License-Identifier: Apache-2.0
// Package narinfo implements a simple narinfo read/writer.
package narinfo
import (
"bufio"
"crypto/md5"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"encoding/base64"
"encoding/hex"
"fmt"
"hash"
"io"
"regexp"
"sort"
"strconv"
"strings"
"github.com/numtide/go-nix/nixbase32"
)
// CompressionMethod lists the supported compression methods.
type CompressionMethod int
const (
CompressionUnknown CompressionMethod = iota
CompressionNone
CompressionXz
CompressionBzip2
CompressionGzip
CompressionBrotli
)
func (c CompressionMethod) String() string {
switch c {
case CompressionNone:
return "none"
case CompressionXz:
return "xz"
case CompressionBzip2:
return "bzip2"
case CompressionGzip:
return "gzip"
case CompressionBrotli:
return "br"
}
return "!!unknown!!"
}
func compressionFromString(s string) CompressionMethod {
switch s {
case "none", "":
return CompressionNone
case "xz":
return CompressionXz
case "bzip2":
return CompressionBzip2
case "gzip":
return CompressionGzip
case "br":
return CompressionBrotli
default:
return CompressionUnknown
}
}
// HashAlgorithm lists the supported hashing algorithms.
type HashAlgorithm int
const (
HashUnknown HashAlgorithm = iota
HashMd5
HashSha1
HashSha256
HashSha512
)
func (a HashAlgorithm) String() string {
switch a {
case HashMd5:
return "md5"
case HashSha1:
return "sha1"
case HashSha256:
return "sha256"
case HashSha512:
return "sha512"
}
return "!!unknown!!"
}
func (a HashAlgorithm) Hash() hash.Hash {
switch a {
case HashMd5:
return md5.New()
case HashSha1:
return sha1.New()
case HashSha256:
return sha256.New()
case HashSha512:
return sha512.New()
}
panic("unknown hash algorithm")
}
func (a HashAlgorithm) sizes() sizes {
sz := a.Hash().Size()
return sizes{
rawLen: sz,
base16Len: hex.EncodedLen(sz),
base32Len: nixbase32.EncodedLen(sz),
base64Len: base64.StdEncoding.EncodedLen(sz),
}
}
type sizes struct {
rawLen int
base16Len int
base32Len int
base64Len int
}
// Hash represents a hash and its algorithm.
type Hash struct {
Algorithm HashAlgorithm
Hash []byte
IsSRI bool
}
// Valid returns if this Hash contains a valid hash.
func (h Hash) Valid() bool {
return h.Algorithm != HashUnknown && len(h.Hash) == h.Algorithm.sizes().rawLen
}
func (h Hash) String() string {
if h.IsSRI {
return fmt.Sprintf("%s-%s", h.Algorithm, base64.StdEncoding.EncodeToString(h.Hash))
}
return fmt.Sprintf("%s:%s", h.Algorithm, nixbase32.EncodeToString(h.Hash))
}
func HashFromString(s string) (Hash, error) {
var h Hash
idx := strings.IndexAny(s, "-:")
if idx == -1 {
return h, fmt.Errorf("no hashtype separator")
}
h.IsSRI = s[idx] == '-'
hashtype, hashdata := s[:idx], s[idx+1:]
switch hashtype {
case "md5":
h.Algorithm = HashMd5
case "sha1":
h.Algorithm = HashSha1
case "sha256":
h.Algorithm = HashSha256
case "sha512":
h.Algorithm = HashSha512
default:
return h, fmt.Errorf("unknown hash type %v", hashtype)
}
var hashbytes []byte
sz := h.Algorithm.sizes()
// We support the same things as Nix, which is base16 (hex), base32 (why), and base64 hashes.
// For SRI, base64 is required.
switch {
case !h.IsSRI && len(hashdata) == sz.base16Len:
var err error
hashbytes, err = hex.DecodeString(hashdata)
if err != nil {
return h, fmt.Errorf("decoding hash %v as hex", hashdata)
}
case !h.IsSRI && len(hashdata) == sz.base32Len:
var err error
hashbytes, err = nixbase32.DecodeString(hashdata)
if err != nil {
return h, fmt.Errorf("decoding hash %v as nix-base32", hashdata)
}
case len(hashdata) == sz.base64Len:
var err error
hashbytes, err = base64.StdEncoding.DecodeString(hashdata)
if err != nil {
return h, fmt.Errorf("decoding hash %v as base64", hashdata)
}
default:
return h, fmt.Errorf("unknown hash type for length %d", len(hashdata))
}
h.Hash = hashbytes
return h, nil
}
// NarInfo represents the content of a .narinfo file.
type NarInfo struct {
StorePath string
URL string
Compression CompressionMethod
FileHash Hash
FileSize uint64
NarHash Hash
NarSize uint64
References []string
Deriver string
System string
Sig map[string][]byte
CA string
}
func (ni NarInfo) WriteTo(w io.Writer) error {
if ni.StorePath != "" {
if _, err := fmt.Fprintf(w, "StorePath: %s\n", ni.StorePath); err != nil {
return err
}
}
if ni.URL != "" {
if _, err := fmt.Fprintf(w, "URL: %s\n", ni.URL); err != nil {
return err
}
}
if ni.Compression != CompressionUnknown {
if _, err := fmt.Fprintf(w, "Compression: %s\n", ni.Compression); err != nil {
return err
}
}
if ni.FileHash.Valid() {
if _, err := fmt.Fprintf(w, "FileHash: %s\n", ni.FileHash); err != nil {
return err
}
}
if ni.FileSize != 0 {
if _, err := fmt.Fprintf(w, "FileSize: %d\n", ni.FileSize); err != nil {
return err
}
}
if ni.NarHash.Valid() {
if _, err := fmt.Fprintf(w, "NarHash: %s\n", ni.NarHash); err != nil {
return err
}
}
if ni.NarSize != 0 {
if _, err := fmt.Fprintf(w, "NarSize: %d\n", ni.NarSize); err != nil {
return err
}
}
if len(ni.References) != 0 {
if _, err := fmt.Fprintf(w, "References: %s\n", strings.Join(ni.References, " ")); err != nil {
return err
}
}
if ni.Deriver != "" {
if _, err := fmt.Fprintf(w, "Deriver: %s\n", ni.Deriver); err != nil {
return err
}
}
if ni.System != "" {
if _, err := fmt.Fprintf(w, "System: %s\n", ni.System); err != nil {
return err
}
}
if len(ni.Sig) != 0 {
sigKeys := make([]string, 0, len(ni.Sig))
for k := range ni.Sig {
sigKeys = append(sigKeys, k)
}
sort.Strings(sigKeys)
for _, k := range sigKeys {
v := ni.Sig[k]
if _, err := fmt.Fprintf(w, "Sig: %s:%s\n", k, base64.StdEncoding.EncodeToString(v)); err != nil {
return err
}
}
}
if ni.CA != "" {
if _, err := fmt.Fprintf(w, "CA: %s\n", ni.CA); err != nil {
return err
}
}
return nil
}
func (ni NarInfo) String() string {
var b strings.Builder
ni.WriteTo(&b)
return b.String()
}
var narLineRegexp = regexp.MustCompile(`^([A-Za-z]+): (.*)$`)
// ParseNarInfo parses NarInfo data from a Reader.
func ParseNarInfo(r io.Reader) (*NarInfo, error) {
ni := NarInfo{
Compression: CompressionBzip2,
}
s := bufio.NewScanner(r)
for s.Scan() {
submatches := narLineRegexp.FindStringSubmatch(s.Text())
switch {
case len(submatches) == 0:
continue
case len(submatches) != 3:
return nil, fmt.Errorf("failed to parse line %q: wrong number of submatches", s.Text())
}
name, value := submatches[1], submatches[2]
switch name {
case "StorePath":
ni.StorePath = value
case "URL":
ni.URL = value
case "Compression":
ni.Compression = compressionFromString(value)
if ni.Compression == CompressionUnknown {
return nil, fmt.Errorf("unknown compression method %q", value)
}
case "FileHash":
h, err := HashFromString(value)
if err != nil {
return nil, fmt.Errorf("parsing %q as FileHash: %w", value, err)
}
ni.FileHash = h
case "FileSize":
var err error
ni.FileSize, err = strconv.ParseUint(value, 10, 64)
if err != nil {
return nil, fmt.Errorf("parsing %q as FileSize: %w", value, err)
}
case "NarHash":
h, err := HashFromString(value)
if err != nil {
return nil, fmt.Errorf("parsing %q as NarHash: %w", value, err)
}
ni.NarHash = h
case "NarSize":
var err error
ni.NarSize, err = strconv.ParseUint(value, 10, 64)
if err != nil {
return nil, fmt.Errorf("parsing %q as NarSize: %w", value, err)
}
case "References":
ni.References = strings.Split(value, " ")
if len(ni.References) == 1 && ni.References[0] == "" {
ni.References = nil
}
case "Deriver":
if value != "unknown-deriver" {
ni.Deriver = value
}
case "System":
ni.System = value
case "Sig":
if ni.Sig == nil {
ni.Sig = make(map[string][]byte)
}
bits := strings.SplitN(value, ":", 2)
if len(bits) != 2 {
return nil, fmt.Errorf("parsing %q as Sig: not enough pieces", value)
}
rawVal, err := base64.StdEncoding.DecodeString(bits[1])
if err != nil {
return nil, fmt.Errorf("parsing %q as Sig: %w", value, err)
}
ni.Sig[bits[0]] = rawVal
case "CA":
ni.CA = value
}
}
if err := s.Err(); err != nil {
return nil, err
}
switch {
case ni.StorePath == "":
return nil, fmt.Errorf("StorePath missing")
case !ni.NarHash.Valid():
return nil, fmt.Errorf("NarHash missing or invalid")
case ni.URL == "":
return nil, fmt.Errorf("URL empty")
case ni.NarSize == 0:
return nil, fmt.Errorf("NAR is 0-size")
}
return &ni, nil
}