ContainerRegistry: Reject other invalid characters in repository names

Author: euanh

Sources/ContainerRegistry/ImageReference.swift

@@ -116,6 +116,7 @@ extension ImageReference {
         public enum ValidationError: Error, Equatable {
             case emptyString
             case containsUppercaseLetters(String)
+            case invalidReferenceFormat(String)
         }
 
         public init(_ rawValue: String) throws {
@@ -129,6 +130,12 @@ extension ImageReference {
                 throw ValidationError.containsUppercaseLetters(rawValue)
             }
 
+            // https://github.com/opencontainers/distribution-spec/blob/main/spec.md#pulling-manifests
+            let regex = /[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*(\/[a-z0-9]+((\.|_|__|-+)[a-z0-9]+)*)*/
+            if try regex.wholeMatch(in: rawValue) == nil {
+                throw ValidationError.invalidReferenceFormat(rawValue)
+            }
+
             value = rawValue
         }
 

Tests/ContainerRegistryTests/ImageReferenceTests.swift

@@ -188,6 +188,10 @@ struct ReferenceTests {
         #expect(throws: ImageReference.Repository.ValidationError.containsUppercaseLetters("helloWorld")) {
             try ImageReference(fromString: "localhost:5555/helloWorld")
         }
+
+        #expect(throws: ImageReference.Repository.ValidationError.invalidReferenceFormat("hello^world")) {
+            try ImageReference(fromString: "localhost:5555/hello^world")
+        }
     }
 
     @Test