leo
e8ac4e39ce
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continuous-integration/drone/push Build is passing
* correctly handle LiveMode resp. whether or not to set/read embeds
116 lines
2.2 KiB
Go
116 lines
2.2 KiB
Go
package funcmap
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import (
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"crypto/sha256"
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"crypto/sha512"
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"encoding/base64"
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"fmt"
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"hash"
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"io"
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"io/fs"
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"os"
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"path/filepath"
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)
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// resIntegrity type implements several methods that allow getting a formatted
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// hash digest for the purpose of checking integrity of a web resource using
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// the algo specified.
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type resIntegrity struct {
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algo string
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}
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const defaultHashAlgo = "sha256"
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// New returns a new resource integrity (resIntegrity) struct for the
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// particular algorithm. Supported argument values are sha256, sha384 and
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// sha512.
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func New(algo string) *resIntegrity { //nolint:revive
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return &resIntegrity{algo: algo}
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}
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// Integrity reads the resource at path, optionally from an fs.FS if parameter
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// live is false (i.e. we're checking embedded resources), and returns a
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// pointer to the integrity string in the form <algo>-<digest>.
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func (i *resIntegrity) Integrity(path string, live bool) (*string, error) {
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r := ""
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// e is an fs.FS created from embed.FS for convenience.
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var e fs.FS
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if embedAssets != nil {
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e = *embedAssets
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}
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h, err := newHash(i.algo)
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if err != nil {
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return &r, err
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}
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if live {
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path = filepath.Join("assets", "public", path)
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f, err := os.Open(path)
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if err != nil {
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return &r, err
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}
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defer f.Close()
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_, err = io.Copy(h, f)
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if err != nil {
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return &r, err
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}
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} else {
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path = filepath.Join("assets", "public", path)
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f, err := e.Open(path)
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if err != nil {
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return &r, err
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}
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defer f.Close()
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_, err = io.Copy(h, f)
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if err != nil {
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return &r, err
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}
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}
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d, err := digest(h)
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if err != nil {
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return &r, err
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}
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r = integrity(i.algo, d)
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return &r, nil
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}
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func newHash(algo string) (hash.Hash, error) {
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switch algo {
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case "sha256":
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return sha256.New(), nil
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case "sha384":
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return sha512.New384(), nil
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case "sha512":
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return sha512.New(), nil
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default:
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return nil, fmt.Errorf("unsupported hash algorithm: %q, use either sha256, sha384 or sha512", algo)
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}
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}
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func integrity(algo string, sum []byte) string {
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if algo == "" {
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algo = defaultHashAlgo
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}
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encoded := base64.StdEncoding.EncodeToString(sum)
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return algo + "-" + encoded
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}
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func digest(h hash.Hash) ([]byte, error) {
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sum := h.Sum(nil)
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return sum, nil
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}
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