Merge pull request #28 from nemunaire/b/signedurl_for_custom_endpoint

Rework presign function to allow signature of clients with dedicated endpoint

presigned.go

@@ -5,6 +5,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"net/url"
+	"path"
 	"sort"
 	"strconv"
 	"strings"
@@ -24,8 +25,6 @@ type PresignedInput struct {
 	Timestamp     time.Time
 	ExtraHeaders  map[string]string
 	ExpirySeconds int
-	Protocol      string
-	Endpoint      string
 }
 
 // GeneratePresignedURL creates a Presigned URL that can be used
@@ -35,8 +34,9 @@ func (s3 *S3) GeneratePresignedURL(in PresignedInput) string {
 	var (
 		nowTime = nowTime()
 
-		protocol = defaultProtocol
+		protocol    = defaultProtocol
-		endpoint = defaultPresignedHost
+		hostname    = defaultPresignedHost
+		path_prefix = ""
 	)
 	if !in.Timestamp.IsZero() {
 		nowTime = in.Timestamp.UTC()
@@ -52,11 +52,16 @@ func (s3 *S3) GeneratePresignedURL(in PresignedInput) string {
 	b.Reset()
 
 	// Set the protocol as default if not provided.
-	if in.Protocol != "" {
+	if endpoint, _ := url.Parse(s3.Endpoint); endpoint.Host != "" {
-		protocol = in.Protocol
+		protocol = endpoint.Scheme + "://"
-	}
+		hostname = endpoint.Host
-	if in.Endpoint != "" {
+		path_prefix = path.Join("/", endpoint.Path, in.Bucket)
-		endpoint = in.Endpoint
+	} else {
+		host := bytes.Buffer{}
+		host.WriteString(in.Bucket)
+		host.WriteRune('.')
+		host.WriteString(hostname)
+		hostname = host.String()
 	}
 
 	// Add host to Headers
@@ -64,16 +69,13 @@ func (s3 *S3) GeneratePresignedURL(in PresignedInput) string {
 	for k, v := range in.ExtraHeaders {
 		signedHeaders[k] = []byte(v)
 	}
-	host := bytes.Buffer{}
+	signedHeaders["host"] = []byte(hostname)
-	host.WriteString(in.Bucket)
-	host.WriteRune('.')
-	host.WriteString(endpoint)
-	signedHeaders["host"] = host.Bytes()
 
 	// Start Canonical Request Formation
 	h := sha256.New()          // We write the canonical request directly to the SHA256 hash.
 	h.Write([]byte(in.Method)) // HTTP Verb
 	h.Write(newLine)
+	h.Write([]byte(path_prefix))
 	h.Write([]byte{'/'})
 	h.Write([]byte(in.ObjectKey)) // CanonicalURL
 	h.Write(newLine)
@@ -193,10 +195,14 @@ func (s3 *S3) GeneratePresignedURL(in PresignedInput) string {
 	b.Reset()
 
 	// Start Generating URL
-	b.WriteString(protocol)
+	if s3.Endpoint != "" {
-	b.WriteString(in.Bucket)
+		b.WriteString(s3.Endpoint)
-	b.WriteRune('.')
+		b.WriteRune('/')
-	b.WriteString(endpoint)
+		b.WriteString(in.Bucket)
+	} else {
+		b.WriteString(protocol)
+		b.WriteString(hostname)
+	}
 	b.WriteRune('/')
 	b.WriteString(in.ObjectKey)
 	b.WriteRune('?')

presigned_test.go

@@ -60,10 +60,10 @@ func TestS3_GeneratePresignedURL_Personal(t *testing.T) {
 			os.Getenv("AWS_S3_ACCESS_KEY"),
 			os.Getenv("AWS_S3_SECRET_KEY"),
 		)
+		s.Endpoint = os.Getenv("AWS_S3_ENDPOINT")
 		dontwant := ""
 		if got := s.GeneratePresignedURL(PresignedInput{
 			Bucket:        os.Getenv("AWS_S3_BUCKET"),
-			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test1.txt",
 			Method:        "GET",
 			Timestamp:     nowTime(),
@@ -81,10 +81,10 @@ func TestS3_GeneratePresignedURL_ExtraHeader(t *testing.T) {
 			os.Getenv("AWS_S3_ACCESS_KEY"),
 			os.Getenv("AWS_S3_SECRET_KEY"),
 		)
+		s.Endpoint = os.Getenv("AWS_S3_ENDPOINT")
 		dontwant := ""
 		if got := s.GeneratePresignedURL(PresignedInput{
 			Bucket:        os.Getenv("AWS_S3_BUCKET"),
-			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test2.txt",
 			Method:        "GET",
 			Timestamp:     nowTime(),
@@ -105,10 +105,10 @@ func TestS3_GeneratePresignedURL_PUT(t *testing.T) {
 			os.Getenv("AWS_S3_ACCESS_KEY"),
 			os.Getenv("AWS_S3_SECRET_KEY"),
 		)
+		s.Endpoint = os.Getenv("AWS_S3_ENDPOINT")
 		dontwant := ""
 		if got := s.GeneratePresignedURL(PresignedInput{
 			Bucket:        os.Getenv("AWS_S3_BUCKET"),
-			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test2.txt",
 			Method:        "PUT",
 			Timestamp:     nowTime(),
@@ -126,13 +126,13 @@ func BenchmarkS3_GeneratePresigned(b *testing.B) {
 		os.Getenv("AWS_S3_ACCESS_KEY"),
 		os.Getenv("AWS_S3_SECRET_KEY"),
 	)
+	s.Endpoint = os.Getenv("AWS_S3_ENDPOINT")
 
 	b.ReportAllocs()
 	b.ResetTimer()
 	for n := 0; n < b.N; n++ {
 		s.GeneratePresignedURL(PresignedInput{
 			Bucket:        os.Getenv("AWS_S3_BUCKET"),
-			Endpoint:      os.Getenv("AWS_S3_ENDPOINT"),
 			ObjectKey:     "test.txt",
 			Method:        "GET",
 			Timestamp:     nowTime(),