package getter
import (
"bufio"
"bytes"
"crypto/md5"
"crypto/sha1"
"crypto/sha256"
"crypto/sha512"
"encoding/hex"
"fmt"
"hash"
"io"
"net/url"
"os"
"path/filepath"
"strings"
urlhelper "github.com/hashicorp/go-getter/helper/url"
)
// FileChecksum helps verifying the checksum for a file.
type FileChecksum struct {
Type string
Hash hash.Hash
Value []byte
Filename string
}
// A ChecksumError is returned when a checksum differs
type ChecksumError struct {
Hash hash.Hash
Actual []byte
Expected []byte
File string
}
func (cerr *ChecksumError) Error() string {
if cerr == nil {
return "<nil>"
}
return fmt.Sprintf(
"Checksums did not match for %s.\nExpected: %s\nGot: %s\n%T",
cerr.File,
hex.EncodeToString(cerr.Expected),
hex.EncodeToString(cerr.Actual),
cerr.Hash, // ex: *sha256.digest
)
}
// checksum is a simple method to compute the checksum of a source file
// and compare it to the given expected value.
func (c *FileChecksum) checksum(source string) error {
f, err := os.Open(source)
if err != nil {
return fmt.Errorf("Failed to open file for checksum: %s", err)
}
defer f.Close()
c.Hash.Reset()
if _, err := io.Copy(c.Hash, f); err != nil {
return fmt.Errorf("Failed to hash: %s", err)
}
if actual := c.Hash.Sum(nil); !bytes.Equal(actual, c.Value) {
return &ChecksumError{
Hash: c.Hash,
Actual: actual,
Expected: c.Value,
File: source,
}
}
return nil
}
// extractChecksum will return a FileChecksum based on the 'checksum'
// parameter of u.
// ex:
// http://hashicorp.com/terraform?checksum=<checksumValue>
// http://hashicorp.com/terraform?checksum=<checksumType>:<checksumValue>
// http://hashicorp.com/terraform?checksum=file:<checksum_url>
// when checksumming from a file, extractChecksum will go get checksum_url
// in a temporary directory, parse the content of the file then delete it.
// Content of files are expected to be BSD style or GNU style.
//
// BSD-style checksum:
// MD5 (file1) = <checksum>
// MD5 (file2) = <checksum>
//
// GNU-style:
// <checksum> file1
// <checksum> *file2
//
// see parseChecksumLine for more detail on checksum file parsing
func (c *Client) extractChecksum(u *url.URL) (*FileChecksum, error) {
q := u.Query()
v := q.Get("checksum")
if v == "" {
return nil, nil
}
vs := strings.SplitN(v, ":", 2)
switch len(vs) {
case 2:
break // good
default:
// here, we try to guess the checksum from it's length
// if the type was not passed
return newChecksumFromValue(v, filepath.Base(u.EscapedPath()))
}
checksumType, checksumValue := vs[0], vs[1]
switch checksumType {
case "file":
return c.ChecksumFromFile(checksumValue, u)
default:
return newChecksumFromType(checksumType, checksumValue, filepath.Base(u.EscapedPath()))
}
}
func newChecksum(checksumValue, filename string) (*FileChecksum, error) {
c := &FileChecksum{
Filename: filename,
}
var err error
c.Value, err = hex.DecodeString(checksumValue)
if err != nil {
return nil, fmt.Errorf("invalid checksum: %s", err)
}
return c, nil
}
func newChecksumFromType(checksumType, checksumValue, filename string) (*FileChecksum, error) {
c, err := newChecksum(checksumValue, filename)
if err != nil {
return nil, err
}
c.Type = strings.ToLower(checksumType)
switch c.Type {
case "md5":
c.Hash = md5.New()
case "sha1":
c.Hash = sha1.New()
case "sha256":
c.Hash = sha256.New()
case "sha512":
c.Hash = sha512.New()
default:
return nil, fmt.Errorf(
"unsupported checksum type: %s", checksumType)
}
return c, nil
}
func newChecksumFromValue(checksumValue, filename string) (*FileChecksum, error) {
c, err := newChecksum(checksumValue, filename)
if err != nil {
return nil, err
}
switch len(c.Value) {
case md5.Size:
c.Hash = md5.New()
c.Type = "md5"
case sha1.Size:
c.Hash = sha1.New()
c.Type = "sha1"
case sha256.Size:
c.Hash = sha256.New()
c.Type = "sha256"
case sha512.Size:
c.Hash = sha512.New()
c.Type = "sha512"
default:
return nil, fmt.Errorf("Unknown type for checksum %s", checksumValue)
}
return c, nil
}
// ChecksumFromFile will return all the FileChecksums found in file
//
// ChecksumFromFile will try to guess the hashing algorithm based on content
// of checksum file
//
// ChecksumFromFile will only return checksums for files that match file
// behind src
func (c *Client) ChecksumFromFile(checksumFile string, src *url.URL) (*FileChecksum, error) {
checksumFileURL, err := urlhelper.Parse(checksumFile)
if err != nil {
return nil, err
}
tempfile, err := tmpFile("", filepath.Base(checksumFileURL.Path))
if err != nil {
return nil, err
}
defer os.Remove(tempfile)
c2 := &Client{
Ctx: c.Ctx,
Getters: c.Getters,
Decompressors: c.Decompressors,
Detectors: c.Detectors,
Pwd: c.Pwd,
Dir: false,
Src: checksumFile,
Dst: tempfile,
ProgressListener: c.ProgressListener,
}
if err = c2.Get(); err != nil {
return nil, fmt.Errorf(
"Error downloading checksum file: %s", err)
}
filename := filepath.Base(src.Path)
absPath, err := filepath.Abs(src.Path)
if err != nil {
return nil, err
}
checksumFileDir := filepath.Dir(checksumFileURL.Path)
relpath, err := filepath.Rel(checksumFileDir, absPath)
switch {
case err == nil ||
err.Error() == "Rel: can't make "+absPath+" relative to "+checksumFileDir:
// ex: on windows C:\gopath\...\content.txt cannot be relative to \
// which is okay, may be another expected path will work.
break
default:
return nil, err
}
// possible file identifiers:
options := []string{
filename, // ubuntu-14.04.1-server-amd64.iso
"*" + filename, // *ubuntu-14.04.1-server-amd64.iso Standard checksum
"?" + filename, // ?ubuntu-14.04.1-server-amd64.iso shasum -p
relpath, // dir/ubuntu-14.04.1-server-amd64.iso
"./" + relpath, // ./dir/ubuntu-14.04.1-server-amd64.iso
absPath, // fullpath; set if local
}
f, err := os.Open(tempfile)
if err != nil {
return nil, fmt.Errorf(
"Error opening downloaded file: %s", err)
}
defer f.Close()
rd := bufio.NewReader(f)
for {
line, err := rd.ReadString('\n')
if err != nil {
if err != io.EOF {
return nil, fmt.Errorf(
"Error reading checksum file: %s", err)
}
break
}
checksum, err := parseChecksumLine(line)
if err != nil || checksum == nil {
continue
}
if checksum.Filename == "" {
// filename not sure, let's try
return checksum, nil
}
// make sure the checksum is for the right file
for _, option := range options {
if option != "" && checksum.Filename == option {
// any checksum will work so we return the first one
return checksum, nil
}
}
}
return nil, fmt.Errorf("no checksum found in: %s", checksumFile)
}
// parseChecksumLine takes a line from a checksum file and returns
// checksumType, checksumValue and filename parseChecksumLine guesses the style
// of the checksum BSD vs GNU by splitting the line and by counting the parts.
// of a line.
// for BSD type sums parseChecksumLine guesses the hashing algorithm
// by checking the length of the checksum.
func parseChecksumLine(line string) (*FileChecksum, error) {
parts := strings.Fields(line)
switch len(parts) {
case 4:
// BSD-style checksum:
// MD5 (file1) = <checksum>
// MD5 (file2) = <checksum>
if len(parts[1]) <= 2 ||
parts[1][0] != '(' || parts[1][len(parts[1])-1] != ')' {
return nil, fmt.Errorf(
"Unexpected BSD-style-checksum filename format: %s", line)
}
filename := parts[1][1 : len(parts[1])-1]
return newChecksumFromType(parts[0], parts[3], filename)
case 2:
// GNU-style:
// <checksum> file1
// <checksum> *file2
return newChecksumFromValue(parts[0], parts[1])
case 0:
return nil, nil // empty line
default:
return newChecksumFromValue(parts[0], "")
}
}
