refactor: extractSignedHeaders() handles headers removed by Go http server (#4054)

* refactor: extractSignedHeaders() handles headers removed by Go http server.
* Cleanup extractSignedHeaders() TestExtractSignedHeaders()

cmd/signature-v4-utils.go

@@ -21,6 +21,7 @@ import (
 	"encoding/hex"
 	"net/http"
 	"regexp"
+	"strconv"
 	"strings"
 	"unicode/utf8"
 
@@ -119,7 +120,14 @@ func extractSignedHeaders(signedHeaders []string, r *http.Request) (http.Header,
 		// `host` will not be found in the headers, can be found in r.Host.
 		// but its alway necessary that the list of signed headers containing host in it.
 		val, ok := reqHeaders[http.CanonicalHeaderKey(header)]
-		if !ok {
+		if ok {
+			for _, enc := range val {
+				extractedSignedHeaders.Add(header, enc)
+			}
+			continue
+		}
+		switch header {
+		case "expect":
 			// Golang http server strips off 'Expect' header, if the
 			// client sent this as part of signed headers we need to
 			// handle otherwise we would see a signature mismatch.
@@ -136,24 +144,23 @@ func extractSignedHeaders(signedHeaders []string, r *http.Request) (http.Header,
 			// be sent, for the time being keep this work around.
 			// Adding a *TODO* to remove this later when Golang server
 			// doesn't filter out the 'Expect' header.
-			if header == "expect" {
-				extractedSignedHeaders[header] = []string{"100-continue"}
-				continue
+			extractedSignedHeaders.Set(header, "100-continue")
+		case "host":
+			// Go http server removes "host" from Request.Header
+			extractedSignedHeaders.Set(header, r.Host)
+		case "transfer-encoding":
+			// Go http server removes "host" from Request.Header
+			for _, enc := range r.TransferEncoding {
+				extractedSignedHeaders.Add(header, enc)
 			}
-			// the "host" field will not be found in the header map, it can be found in req.Host.
-			// but its necessary to make sure that the "host" field exists in the list of signed parameters,
-			// the check is done above.
-			if header == "host" {
-				continue
-			}
-			if header == "transfer-encoding" {
-				extractedSignedHeaders[header] = r.TransferEncoding
-				continue
-			}
-			// If not found continue, we will stop here.
+		case "content-length":
+			// Signature-V4 spec excludes Content-Length from signed headers list for signature calculation.
+			// But some clients deviate from this rule. Hence we consider Content-Length for signature
+			// calculation to be compatible with such clients.
+			extractedSignedHeaders.Set(header, strconv.FormatInt(r.ContentLength, 10))
+		default:
 			return nil, ErrUnsignedHeaders
 		}
-		extractedSignedHeaders[header] = val
 	}
 	return extractedSignedHeaders, ErrNone
 }

cmd/signature-v4-utils_test.go

@@ -141,8 +141,9 @@ func TestExtractSignedHeaders(t *testing.T) {
 	expectedContentSha256 := "1234abcd"
 	expectedTime := UTCNow().Format(iso8601Format)
 	expectedTransferEncoding := "gzip"
+	expectedExpect := "100-continue"
 
-	r, err := http.NewRequest("GET", "http://localhost", nil)
+	r, err := http.NewRequest("GET", "http://play.minio.io:9000", nil)
 	if err != nil {
 		t.Fatal("Unable to create http.Request :", err)
 	}
@@ -150,9 +151,8 @@ func TestExtractSignedHeaders(t *testing.T) {
 
 	// Creating input http header.
 	inputHeader := r.Header
-	inputHeader.Set(signedHeaders[0], expectedHost)
-	inputHeader.Set(signedHeaders[1], expectedContentSha256)
-	inputHeader.Set(signedHeaders[2], expectedTime)
+	inputHeader.Set("x-amz-content-sha256", expectedContentSha256)
+	inputHeader.Set("x-amz-date", expectedTime)
 	// calling the function being tested.
 	extractedSignedHeaders, errCode := extractSignedHeaders(signedHeaders, r)
 	if errCode != ErrNone {
@@ -160,24 +160,24 @@ func TestExtractSignedHeaders(t *testing.T) {
 	}
 
 	// "x-amz-content-sha256" header value from the extracted result.
-	extractedContentSha256 := extractedSignedHeaders[signedHeaders[1]]
+	extractedContentSha256 := extractedSignedHeaders.Get("x-amz-content-sha256")
 	// "host" header value from the extracted result.
-	extractedHost := extractedSignedHeaders[signedHeaders[0]]
+	extractedHost := extractedSignedHeaders.Get("host")
 	//  "x-amz-date" header from the extracted result.
-	extractedDate := extractedSignedHeaders[signedHeaders[2]]
+	extractedDate := extractedSignedHeaders.Get("x-amz-date")
 	// extracted `expect` header.
-	extractedExpect := extractedSignedHeaders["expect"][0]
+	extractedExpect := extractedSignedHeaders.Get("expect")
 
-	extractedTransferEncoding := extractedSignedHeaders["transfer-encoding"][0]
+	extractedTransferEncoding := extractedSignedHeaders.Get("transfer-encoding")
 
-	if expectedHost != extractedHost[0] {
+	if expectedHost != extractedHost {
 		t.Errorf("host header mismatch: expected `%s`, got `%s`", expectedHost, extractedHost)
 	}
 	// assert the result with the expected value.
-	if expectedContentSha256 != extractedContentSha256[0] {
+	if expectedContentSha256 != extractedContentSha256 {
 		t.Errorf("x-amz-content-sha256 header mismatch: expected `%s`, got `%s`", expectedContentSha256, extractedContentSha256)
 	}
-	if expectedTime != extractedDate[0] {
+	if expectedTime != extractedDate {
 		t.Errorf("x-amz-date header mismatch: expected `%s`, got `%s`", expectedTime, extractedDate)
 	}
 	if extractedTransferEncoding != expectedTransferEncoding {
@@ -185,12 +185,12 @@ func TestExtractSignedHeaders(t *testing.T) {
 	}
 
 	// Since the list of signed headers value contained `expect`, the default value of `100-continue` will be added to extracted signed headers.
-	if extractedExpect != "100-continue" {
-		t.Errorf("expect header incorrect value: expected `%s`, got `%s`", "100-continue", extractedExpect)
+	if extractedExpect != expectedExpect {
+		t.Errorf("expect header incorrect value: expected `%s`, got `%s`", expectedExpect, extractedExpect)
 	}
 
-	// case where the headers doesn't contain the one of the signed header in the signed headers list.
-	signedHeaders = append(signedHeaders, " X-Amz-Credential")
+	// case where the headers don't contain the one of the signed header in the signed headers list.
+	signedHeaders = append(signedHeaders, "X-Amz-Credential")
 	// expected to fail with `ErrUnsignedHeaders`.
 	_, errCode = extractSignedHeaders(signedHeaders, r)
 	if errCode != ErrUnsignedHeaders {
@@ -198,7 +198,7 @@ func TestExtractSignedHeaders(t *testing.T) {
 	}
 
 	// case where the list of signed headers doesn't contain the host field.
-	signedHeaders = signedHeaders[1:]
+	signedHeaders = signedHeaders[2:5]
 	// expected to fail with `ErrUnsignedHeaders`.
 	_, errCode = extractSignedHeaders(signedHeaders, r)
 	if errCode != ErrUnsignedHeaders {

cmd/signature-v4.go

@@ -46,33 +46,26 @@ const (
 )
 
 // getCanonicalHeaders generate a list of request headers with their values
-func getCanonicalHeaders(signedHeaders http.Header, host string) string {
+func getCanonicalHeaders(signedHeaders http.Header) string {
 	var headers []string
 	vals := make(http.Header)
 	for k, vv := range signedHeaders {
 		headers = append(headers, strings.ToLower(k))
 		vals[strings.ToLower(k)] = vv
 	}
-	headers = append(headers, presignedHostHeader)
 	sort.Strings(headers)
 
 	var buf bytes.Buffer
 	for _, k := range headers {
 		buf.WriteString(k)
 		buf.WriteByte(':')
-		switch {
-		case k == presignedHostHeader:
-			buf.WriteString(host)
-			fallthrough
-		default:
-			for idx, v := range vals[k] {
-				if idx > 0 {
-					buf.WriteByte(',')
-				}
-				buf.WriteString(signV4TrimAll(v))
+		for idx, v := range vals[k] {
+			if idx > 0 {
+				buf.WriteByte(',')
 			}
-			buf.WriteByte('\n')
+			buf.WriteString(signV4TrimAll(v))
 		}
+		buf.WriteByte('\n')
 	}
 	return buf.String()
 }
@@ -83,7 +76,6 @@ func getSignedHeaders(signedHeaders http.Header) string {
 	for k := range signedHeaders {
 		headers = append(headers, strings.ToLower(k))
 	}
-	headers = append(headers, presignedHostHeader)
 	sort.Strings(headers)
 	return strings.Join(headers, ";")
 }
@@ -98,14 +90,14 @@ func getSignedHeaders(signedHeaders http.Header) string {
 //  <SignedHeaders>\n
 //  <HashedPayload>
 //
-func getCanonicalRequest(extractedSignedHeaders http.Header, payload, queryStr, urlPath, method, host string) string {
+func getCanonicalRequest(extractedSignedHeaders http.Header, payload, queryStr, urlPath, method string) string {
 	rawQuery := strings.Replace(queryStr, "+", "%20", -1)
 	encodedPath := getURLEncodedName(urlPath)
 	canonicalRequest := strings.Join([]string{
 		method,
 		encodedPath,
 		rawQuery,
-		getCanonicalHeaders(extractedSignedHeaders, host),
+		getCanonicalHeaders(extractedSignedHeaders),
 		getSignedHeaders(extractedSignedHeaders),
 		payload,
 	}, "\n")
@@ -304,7 +296,7 @@ func doesPresignedSignatureMatch(hashedPayload string, r *http.Request, region s
 	/// Verify finally if signature is same.
 
 	// Get canonical request.
-	presignedCanonicalReq := getCanonicalRequest(extractedSignedHeaders, hashedPayload, encodedQuery, req.URL.Path, req.Method, req.Host)
+	presignedCanonicalReq := getCanonicalRequest(extractedSignedHeaders, hashedPayload, encodedQuery, req.URL.Path, req.Method)
 
 	// Get string to sign from canonical request.
 	presignedStringToSign := getStringToSign(presignedCanonicalReq, t, pSignValues.Credential.getScope())
@@ -346,19 +338,6 @@ func doesSignatureMatch(hashedPayload string, r *http.Request, region string) AP
 		return ErrContentSHA256Mismatch
 	}
 
-	header := req.Header
-
-	// Signature-V4 spec excludes Content-Length from signed headers list for signature calculation.
-	// But some clients deviate from this rule. Hence we consider Content-Length for signature
-	// calculation to be compatible with such clients.
-	for _, h := range signV4Values.SignedHeaders {
-		if h == "content-length" {
-			header = cloneHeader(req.Header)
-			header.Set("content-length", strconv.FormatInt(r.ContentLength, 10))
-			break
-		}
-	}
-
 	// Extract all the signed headers along with its values.
 	extractedSignedHeaders, errCode := extractSignedHeaders(signV4Values.SignedHeaders, r)
 	if errCode != ErrNone {
@@ -401,8 +380,7 @@ func doesSignatureMatch(hashedPayload string, r *http.Request, region string) AP
 	queryStr := req.URL.Query().Encode()
 
 	// Get canonical request.
-	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, hashedPayload, queryStr, req.URL.Path, req.Method, req.Host)
-
+	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, hashedPayload, queryStr, req.URL.Path, req.Method)
 	// Get string to sign from canonical request.
 	stringToSign := getStringToSign(canonicalRequest, t, signV4Values.Credential.getScope())
 

cmd/streaming-signature-v4.go

@@ -133,7 +133,7 @@ func calculateSeedSignature(r *http.Request) (signature string, date time.Time,
 	queryStr := req.URL.Query().Encode()
 
 	// Get canonical request.
-	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, payload, queryStr, req.URL.Path, req.Method, req.Host)
+	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, payload, queryStr, req.URL.Path, req.Method)
 
 	// Get string to sign from canonical request.
 	stringToSign := getStringToSign(canonicalRequest, date, signV4Values.Credential.getScope())

cmd/test-utils_test.go

@@ -889,11 +889,12 @@ func preSignV4(req *http.Request, accessKeyID, secretAccessKey string, expires i
 	query.Set("X-Amz-Credential", credential)
 	query.Set("X-Amz-Content-Sha256", unsignedPayload)
 
-	// Headers are empty, since "host" is the only header required to be signed for Presigned URLs.
-	var extractedSignedHeaders http.Header
+	// "host" is the only header required to be signed for Presigned URLs.
+	extractedSignedHeaders := make(http.Header)
+	extractedSignedHeaders.Set("host", req.Host)
 
 	queryStr := strings.Replace(query.Encode(), "+", "%20", -1)
-	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, unsignedPayload, queryStr, req.URL.Path, req.Method, req.Host)
+	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, unsignedPayload, queryStr, req.URL.Path, req.Method)
 	stringToSign := getStringToSign(canonicalRequest, date, scope)
 	signingKey := getSigningKey(secretAccessKey, date, region)
 	signature := getSignature(signingKey, stringToSign)

cmd/web-handlers.go

@@ -868,10 +868,10 @@ func presignedGet(host, bucket, object string, expiry int64) string {
 
 	path := "/" + path.Join(bucket, object)
 
-	// Headers are empty, since "host" is the only header required to be signed for Presigned URLs.
-	var extractedSignedHeaders http.Header
-
-	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, unsignedPayload, query, path, "GET", host)
+	// "host" is the only header required to be signed for Presigned URLs.
+	extractedSignedHeaders := make(http.Header)
+	extractedSignedHeaders.Set("host", host)
+	canonicalRequest := getCanonicalRequest(extractedSignedHeaders, unsignedPayload, query, path, "GET")
 	stringToSign := getStringToSign(canonicalRequest, date, getScope(date, region))
 	signingKey := getSigningKey(secretKey, date, region)
 	signature := getSignature(signingKey, stringToSign)