/
anchor_parser.go
110 lines (88 loc) · 2.7 KB
/
anchor_parser.go
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package anchor
import (
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"errors"
"fmt"
"github.com/getyoti/yoti-go-sdk/v3/yotiprotoattr"
"github.com/getyoti/yoti-go-sdk/v3/yotiprotocom"
"google.golang.org/protobuf/proto"
)
type anchorExtension struct {
Extension string `asn1:"tag:0,utf8"`
}
var (
sourceOID = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 47127, 1, 1, 1}
verifierOID = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 47127, 1, 1, 2}
)
// ParseAnchors takes a slice of protobuf anchors, parses them, and returns a slice of Yoti SDK Anchors
func ParseAnchors(protoAnchors []*yotiprotoattr.Anchor) []*Anchor {
var processedAnchors []*Anchor
for _, protoAnchor := range protoAnchors {
parsedCerts := parseCertificates(protoAnchor.OriginServerCerts)
anchorType, extension := getAnchorValuesFromCertificate(parsedCerts)
parsedSignedTimestamp, err := parseSignedTimestamp(protoAnchor.SignedTimeStamp)
if err != nil {
continue
}
processedAnchor := newAnchor(anchorType, parsedCerts, parsedSignedTimestamp, protoAnchor.SubType, extension)
processedAnchors = append(processedAnchors, processedAnchor)
}
return processedAnchors
}
func getAnchorValuesFromCertificate(parsedCerts []*x509.Certificate) (anchorType Type, extension string) {
defaultAnchorType := TypeUnknown
for _, cert := range parsedCerts {
for _, ext := range cert.Extensions {
var (
value string
err error
)
parsedAnchorType, value, err := parseExtension(ext)
if err != nil {
continue
} else if parsedAnchorType == TypeUnknown {
continue
}
return parsedAnchorType, value
}
}
return defaultAnchorType, ""
}
func parseExtension(ext pkix.Extension) (anchorType Type, val string, err error) {
anchorType = TypeUnknown
switch {
case ext.Id.Equal(sourceOID):
anchorType = TypeSource
case ext.Id.Equal(verifierOID):
anchorType = TypeVerifier
default:
return anchorType, "", nil
}
var ae anchorExtension
_, err = asn1.Unmarshal(ext.Value, &ae)
switch {
case err != nil:
return anchorType, "", fmt.Errorf("unable to unmarshal extension: %v", err)
case len(ae.Extension) == 0:
return anchorType, "", errors.New("empty extension")
default:
val = ae.Extension
}
return anchorType, val, nil
}
func parseSignedTimestamp(rawBytes []byte) (*yotiprotocom.SignedTimestamp, error) {
signedTimestamp := &yotiprotocom.SignedTimestamp{}
if err := proto.Unmarshal(rawBytes, signedTimestamp); err != nil {
return signedTimestamp, err
}
return signedTimestamp, nil
}
func parseCertificates(rawCerts [][]byte) (result []*x509.Certificate) {
for _, cert := range rawCerts {
parsedCertificate, _ := x509.ParseCertificate(cert)
result = append(result, parsedCertificate)
}
return result
}