pub key representation parsing 2/..

pubKeyRep.go

@@ -2,8 +2,11 @@ package dkim
 
 import (
 	"crypto/rsa"
+	"crypto/x509"
+	"encoding/base64"
 	"fmt"
 	"net"
+	"strings"
 )
 
 // pubKeyRep represents a parsed version of public key record
@@ -18,9 +21,84 @@ type pubKeyRep struct {
 	FlagIMustBeD bool // flag i
 }
 
-func newPubKeyFromDnsTxt(selector, domain string) (*pubKeyRep, error) {
+func newPubKeyFromDnsTxt(selector, domain string) (*pubKeyRep, VerifyOutput, error) {
 	txt, err := net.LookupTXT(selector + "._domainkey." + domain)
+	if err != nil {
+		if strings.HasSuffix(err.Error(), "no such host") {
+			return nil, PERMFAIL, ErrVerifyNoKeyForSignature
+		} else {
+			return nil, TEMPFAIL, ErrVerifyKeyUnavailable
+		}
+	}
+
+	// empty record
+	if len(txt) == 0 {
+		return nil, PERMFAIL, ErrVerifyNoKeyForSignature
+	}
+
+	pkr := new(pubKeyRep)
+	pkr.Version = "DKIM1"
+	pkr.HashAlgo = []string{"sha1", "sha256"}
+	pkr.KeyType = "rsa"
+
+	// parsing, we keep the first record
+	// TODO: if there is multiple record
+
+	p := strings.Split(txt[0], ";")
+	for i, data := range p {
+		keyVal := strings.SplitN(data, "=", 2)
+		switch strings.ToLower(strings.TrimSpace(keyVal[0])) {
+		case "v":
+			// RFC: is this tag is specified it MUST be the first in the record
+			if i != 0 {
+				return nil, PERMFAIL, ErrVerifyTagVMustBeTheFirst
+			}
+			pkr.Version = strings.TrimSpace(keyVal[1])
+			if pkr.Version != "DKIM1" {
+				return nil, PERMFAIL, ErrVerifyVersionMusBeDkim1
+			}
+		case "h":
+			p := strings.Split(strings.ToLower(keyVal[1]), ":")
+			pkr.HashAlgo = []string{}
+			for _, h := range p {
+				h = strings.TrimSpace(h)
+				if h == "sha1" || h == "sha256" {
+					pkr.HashAlgo = append(pkr.HashAlgo, h)
+				}
+			}
+			// if empty switch back to default
+			if len(pkr.HashAlgo) == 0 {
+				pkr.HashAlgo = []string{"sha1", "sha256"}
+			}
+		case "k":
+			if strings.ToLower(strings.TrimSpace(keyVal[1])) != "rsa" {
+				return nil, PERMFAIL, ErrVerifyBadKeyType
+			}
+		case "n":
+			pkr.Note = strings.TrimSpace(keyVal[1])
+		case "p":
+			rawkey := strings.TrimSpace(keyVal[1])
+			if rawkey == "" {
+				return nil, PERMFAIL, ErrVerifyRevokedKey
+			}
+			// x509.ParsePKIXPublicKey(Dkim.PublicKey.PublicKey)
+			un64, err := base64.StdEncoding.DecodeString(rawkey)
+			if err != nil {
+				return nil, PERMFAIL, ErrVerifyBadKey
+			}
+			pk, err := x509.ParsePKIXPublicKey(un64)
+			pkr.PubKey = *pk.(*rsa.PublicKey)
+		// HERE
+		case "s":
+		case "t":
+
+		}
+
+	}
+
+	// TODO: If no pubkey
+
 	fmt.Println(txt, err)
 
-	return nil, nil
+	return nil, SUCCESS, nil
 }