S3: set identity to request context, and remove obsolete code (#7523)

* list owned buckets

* simplify

* add unit tests

* no-owner buckets

* set identity id

* fallback to request header if iam is not enabled

* refactor to test

* fix comparing

* fix security vulnerability

* Update s3api_bucket_handlers.go

* Update s3api_bucket_handlers.go

* Update s3api_bucket_handlers.go

* set identity to request context

* remove SeaweedFSIsDirectoryKey

* remove obsolete

* simplify

* reuse

* refactor or remove obsolete logic on filer

* Removed the redundant check in GetOrHeadHandler

* surfacing invalid X-Amz-Tagging as a client error

* clean up

* constant

* reuse

* multiple header values

* code reuse

* err on duplicated tag key

weed/s3api/s3_constants/header.go

@@ -17,6 +17,7 @@
 package s3_constants
 
 import (
+	"context"
 	"net/http"
 	"strings"
 
@@ -44,8 +45,6 @@ const (
 	AmzObjectTaggingDirective = "X-Amz-Tagging-Directive"
 	AmzTagCount               = "x-amz-tagging-count"
 
-	SeaweedFSIsDirectoryKey          = "X-Seaweedfs-Is-Directory-Key"
-	SeaweedFSPartNumber              = "X-Seaweedfs-Part-Number"
 	SeaweedFSUploadId                = "X-Seaweedfs-Upload-Id"
 	SeaweedFSMultipartPartsCount     = "X-Seaweedfs-Multipart-Parts-Count"
 	SeaweedFSMultipartPartBoundaries = "X-Seaweedfs-Multipart-Part-Boundaries" // JSON: [{part:1,start:0,end:2,etag:"abc"},{part:2,start:2,end:3,etag:"def"}]
@@ -174,3 +173,29 @@ var PassThroughHeaders = map[string]string{
 func IsSeaweedFSInternalHeader(headerKey string) bool {
 	return strings.HasPrefix(strings.ToLower(headerKey), SeaweedFSInternalPrefix)
 }
+
+// Context keys for storing authenticated identity information
+type contextKey string
+
+const (
+	contextKeyIdentityName contextKey = "s3-identity-name"
+)
+
+// SetIdentityNameInContext stores the authenticated identity name in the request context
+// This is the secure way to propagate identity - headers can be spoofed, context cannot
+func SetIdentityNameInContext(ctx context.Context, identityName string) context.Context {
+	if identityName != "" {
+		return context.WithValue(ctx, contextKeyIdentityName, identityName)
+	}
+	return ctx
+}
+
+// GetIdentityNameFromContext retrieves the authenticated identity name from the request context
+// Returns empty string if no identity is set (unauthenticated request)
+// This is the secure way to retrieve identity - never read from headers directly
+func GetIdentityNameFromContext(r *http.Request) string {
+	if name, ok := r.Context().Value(contextKeyIdentityName).(string); ok {
+		return name
+	}
+	return ""
+}