A Mount dial with a network pardes does not dial (`nowhere!x`) is a bad dial address, EINVAL, not a session name that does not answer

A dial with a `!` and no `/` that was neither tcp!, quic! nor unix! was
taken for a session's name, failing as `dial failed: no answer`, EIO.
It is now refused as the malformed address it is, before any dial. A
path with a `!` in it still dials.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/9p_io.zig b/src/9p_io.zig
index a4340ddf..e199dea9 100644
--- a/src/9p_io.zig
+++ b/src/9p_io.zig
@@ -1425,6 +1425,8 @@ test "TCP addresses are numeric and normalize mapped IPv4" {
     try Client.validateDial("/tmp/pardes-owned.sock");
     try Client.validateDial("unix!/tmp/pardes-owned.sock");
     try testing.expectError(error.BadDial, Client.validateDial("unix!work"));
+    try testing.expectError(error.BadDial, Client.validateDial("nowhere!x"));
+    try Client.validateDial("/tmp/odd!name.sock");
     try testing.expectError(error.BadDial, Client.validateDial("unix!"));
     try testing.expectError(error.BadDial, Client.validateDial("unix!/tmp/a\x00b"));
     try testing.expectError(error.BadDial, Client.validateDial("tcp!localhost!5640"));
@@ -2078,6 +2080,9 @@ pub const Client = struct {
             return .{ .quic = try networkAddress(dial, false) };
         }
         const explicit_unix = std.mem.startsWith(u8, dial, "unix!");
+        // A network this does not dial (`nowhere!x`) is a malformed address,
+        // not a session named so.
+        if (!explicit_unix and std.mem.indexOfScalar(u8, dial, '/') == null and std.mem.indexOfScalar(u8, dial, '!') != null) return error.BadDial;
         const path = if (explicit_unix) dial[5..] else dial;
         if (explicit_unix and !std.mem.startsWith(u8, path, "/")) return error.BadDial;
         if (std.mem.indexOfScalar(u8, path, '/') != null) {