Merge pull request toorop#19 from terrabitz/Export-function-to-get-pa…

…rsed-header

Expose and rename newDkimHeaderFromEmail

dkim.go

@@ -202,7 +202,7 @@ func Sign(email *[]byte, options SigOptions) error {
 // error: if an error occurs during verification
 func Verify(email *[]byte, opts ...DNSOpt) (verifyOutput, error) {
 	// parse email
-	dkimHeader, err := newDkimHeaderFromEmail(email)
+	dkimHeader, err := GetHeader(email)
 	if err != nil {
 		if err == ErrDkimHeaderNotFound {
 			return NOTSIGNED, ErrDkimHeaderNotFound
@@ -254,7 +254,7 @@ func Verify(email *[]byte, opts ...DNSOpt) (verifyOutput, error) {
 	}
 
 	// compute sig
-	dkimHeaderCano, err := canonicalizeHeader(dkimHeader.RawForSign, strings.Split(dkimHeader.MessageCanonicalization, "/")[0])
+	dkimHeaderCano, err := canonicalizeHeader(dkimHeader.rawForSign, strings.Split(dkimHeader.MessageCanonicalization, "/")[0])
 	if err != nil {
 		return getVerifyOutput(TEMPFAIL, err, pubKey.FlagTesting)
 	}

dkimHeader.go

@@ -10,7 +10,7 @@ import (
 	"time"
 )
 
-type dkimHeader struct {
+type DKIMHeader struct {
 	// Version  This tag defines the version of DKIM
 	// specification that applies to the signature record.
 	// tag v
@@ -193,12 +193,12 @@ type dkimHeader struct {
 
 	// RawForsign represents the raw part (without canonicalization) of the header
 	// used for computint sig in verify process
-	RawForSign string
+	rawForSign string
 }
 
 // NewDkimHeaderBySigOptions return a new DkimHeader initioalized with sigOptions value
-func newDkimHeaderBySigOptions(options SigOptions) *dkimHeader {
-	h := new(dkimHeader)
+func newDkimHeaderBySigOptions(options SigOptions) *DKIMHeader {
+	h := new(DKIMHeader)
 	h.Version = "1"
 	h.Algorithm = options.Algo
 	h.MessageCanonicalization = options.Canonicalization
@@ -218,10 +218,10 @@ func newDkimHeaderBySigOptions(options SigOptions) *dkimHeader {
 	return h
 }
 
-// NewFromEmail return a new DkimHeader by parsing an email
+// GetHeader return a new DKIMHeader by parsing an email
 // Note: according to RFC 6376 an email can have multiple DKIM Header
 // in this case we return the last inserted or the last with d== mail from
-func newDkimHeaderFromEmail(email *[]byte) (*dkimHeader, error) {
+func GetHeader(email *[]byte) (*DKIMHeader, error) {
 	m, err := mail.ReadMessage(bytes.NewReader(*email))
 	if err != nil {
 		return nil, err
@@ -265,7 +265,7 @@ func newDkimHeaderFromEmail(email *[]byte) (*dkimHeader, error) {
 		}
 	}
 
-	var keep *dkimHeader
+	var keep *DKIMHeader
 	var keepErr error
 	//for _, dk := range m.Header[textproto.CanonicalMIMEHeaderKey("DKIM-Signature")] {
 	for _, h := range dkHeaders {
@@ -291,19 +291,19 @@ func newDkimHeaderFromEmail(email *[]byte) (*dkimHeader, error) {
 }
 
 // parseDkHeader parse raw dkim header
-func parseDkHeader(header string) (dkh *dkimHeader, err error) {
-	dkh = new(dkimHeader)
+func parseDkHeader(header string) (dkh *DKIMHeader, err error) {
+	dkh = new(DKIMHeader)
 
 	keyVal := strings.SplitN(header, ":", 2)
 
 	t := strings.LastIndex(header, "b=")
 	if t == -1 {
 		return nil, ErrDkimHeaderBTagNotFound
 	}
-	dkh.RawForSign = header[0 : t+2]
+	dkh.rawForSign = header[0 : t+2]
 	p := strings.IndexByte(header[t:], ';')
 	if p != -1 {
-		dkh.RawForSign = dkh.RawForSign + header[t+p:]
+		dkh.rawForSign = dkh.rawForSign + header[t+p:]
 	}
 
 	// Mandatory
@@ -452,7 +452,7 @@ func parseDkHeader(header string) (dkh *dkimHeader, err error) {
 
 // GetHeaderBase return base header for signers
 // Todo: some refactoring needed...
-func (d *dkimHeader) getHeaderBaseForSigning(bodyHash string) string {
+func (d *DKIMHeader) getHeaderBaseForSigning(bodyHash string) string {
 	h := "DKIM-Signature: v=" + d.Version + "; a=" + d.Algorithm + "; q=" + strings.Join(d.QueryMethods, ":") + "; c=" + d.MessageCanonicalization + ";" + CRLF + TAB
 	subh := "s=" + d.Selector + ";"
 	if len(subh)+len(d.Domain)+4 > MaxHeaderLineLength {

dkimHeader_test.go

@@ -0,0 +1,54 @@
+package dkim
+
+import (
+	"testing"
+
+	"github.com/go-test/deep"
+)
+
+func Test_GetHeader(t *testing.T) {
+	tests := []struct {
+		name    string
+		input   string
+		want    *DKIMHeader
+		wantErr bool
+	}{
+		{
+			name:  "Signed relaxed with length",
+			input: signedRelaxedRelaxedLength,
+			want: &DKIMHeader{
+				Version:                 "1",
+				Algorithm:               "rsa-sha256",
+				QueryMethods:            []string{"dns/txt"},
+				MessageCanonicalization: "relaxed/relaxed",
+				Selector:                "test",
+				Domain:                  "tmail.io",
+				Auid:                    "@tmail.io",
+				BodyLength:              5,
+				Headers:                 []string{"from", "date", "mime-version", "received", "received"},
+				BodyHash:                "GF+NsyJx/iX1Yab8k4suJkMG7DBO2lGAB9F2SCY4GWk=",
+				SignatureData: "byhiFWd0lAM1sqD1tl8S1DZtKNqgiEZp8jrGds6RRydnZkdX9rCPeL0Q5MYWBQ/JmQrml5" +
+					"pIghLwl/EshDBmNy65O6qO8pSSGgZmM3T7SRLMloex8bnrBJ4KSYcHV46639gVEWcBOKW0" +
+					"h1djZu2jaTuxGeJzlFVtw3Arf2B93cc=",
+			},
+		},
+		{
+			name:    "No signature",
+			input:   bodySimple,
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			email := []byte(tt.input)
+			got, err := GetHeader(&email)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("GetHeader() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if diff := deep.Equal(tt.want, got); diff != nil {
+				t.Error(diff)
+			}
+		})
+	}
+}