Break up <??> differently, and explain why

diff --git a/src/or/ext_orport.c b/src/or/ext_orport.c
index cd8ab2d04e45a282a3be5a716136f6fb4bb2e34f..72dbaa55a7c2f400bc95d0576d659b4294eb4142 100644 (file)
--- a/src/or/ext_orport.c
+++ b/src/or/ext_orport.c
@@ -515,8 +515,11 @@ connection_ext_or_process_inbuf(or_connection_t *or_conn)
 
       /* If the transport proxy did not use the TRANSPORT command to
        * specify the transport name, mark this as unknown transport. */
-      if (!or_conn->ext_or_transport)
-        or_conn->ext_or_transport = tor_strdup("<?\?>");
+      if (!or_conn->ext_or_transport) {
+        /* We write this string this way to avoid ??>, which is a C
+         * trigraph. */
+        or_conn->ext_or_transport = tor_strdup("<?" "?>");
+      }
 
       connection_write_ext_or_command(conn, EXT_OR_CMD_BT_OKAY, NULL, 0);