[#106] Add chunk uploading

Signed-off-by: Artem Tataurov <a.tataurov@yadro.com>

api/headers.go

@@ -1,5 +1,7 @@
 package api
 
+import "net/http"
+
 // Standard S3 HTTP request/response constants.
 const (
 	MetadataPrefix              = "X-Amz-Meta-"
@@ -39,11 +41,13 @@ const (
 	IfMatch            = "If-Match"
 	IfNoneMatch        = "If-None-Match"
 
+	AmzContentSha256             = "X-Amz-Content-Sha256"
 	AmzCopyIfModifiedSince       = "X-Amz-Copy-Source-If-Modified-Since"
 	AmzCopyIfUnmodifiedSince     = "X-Amz-Copy-Source-If-Unmodified-Since"
 	AmzCopyIfMatch               = "X-Amz-Copy-Source-If-Match"
 	AmzCopyIfNoneMatch           = "X-Amz-Copy-Source-If-None-Match"
 	AmzACL                       = "X-Amz-Acl"
+	AmzDecodedContentLength      = "X-Amz-Decoded-Content-Length"
 	AmzGrantFullControl          = "X-Amz-Grant-Full-Control"
 	AmzGrantRead                 = "X-Amz-Grant-Read"
 	AmzGrantWrite                = "X-Amz-Grant-Write"
@@ -78,9 +82,13 @@ const (
 	AccessControlRequestMethod  = "Access-Control-Request-Method"
 	AccessControlRequestHeaders = "Access-Control-Request-Headers"
 
+	AwsChunked = "aws-chunked"
+
 	Vary = "Vary"
 
 	DefaultLocationConstraint = "default"
+
+	StreamingContentSHA256 = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD"
 )
 
 // S3 request query params.
@@ -107,3 +115,12 @@ var SystemMetadata = map[string]struct{}{
 	LastModified:       {},
 	ETag:               {},
 }
+
+func IsSignedStreamingV4(r *http.Request) bool {
+	// The Content-Encoding must have "aws-chunked" as part of its value.
+	// https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-streaming.html
+	// Minio does not set this value, thus for compatibility reasons
+	// we do not check it.
+	return r.Header.Get(AmzContentSha256) == StreamingContentSHA256 &&
+		r.Method == http.MethodPut
+}