Need to lock the NilTokens List since multiple threads may be trying …

…to add to it
jstedfast · Aug 20, 2023 · 50b06a7 · 50b06a7
1 parent 6ed1bef
commit 50b06a7
Showing 1 changed file with 12 additions and 8 deletions.
diff --git a/MailKit/Net/Imap/ImapToken.cs b/MailKit/Net/Imap/ImapToken.cs
@@ -137,17 +137,21 @@ public static ImapToken Create (ImapTokenType type, ByteArrayBuilder builder)
 				}
 			} else if (type == ImapTokenType.Atom) {
 				if (builder.Equals ("NIL", true)) {
-					foreach (var token in NilTokens) {
-						value = (string) token.Value;
+					// Look for the cached NIL token that matches this capitalization.
+					lock (NilTokens) {
+						foreach (var token in NilTokens) {
+							value = (string) token.Value;
 
-						if (builder.Equals (value))
-							return token;
-					}
+							if (builder.Equals (value))
+								return token;
+						}
 
-					var nil = new ImapToken (ImapTokenType.Nil, builder.ToString ());
-					NilTokens.Add (nil);
+						// Add this new variation to our NIL token cache.
+						var nil = new ImapToken (ImapTokenType.Nil, builder.ToString ());
+						NilTokens.Add (nil);
 
-					return nil;
+						return nil;
+					}
 				}
 
 				if (builder.Equals ("FETCH", false))