From: Nick Mathewson <nickm@torproject.org>
Date: Thu, 17 Apr 2025 23:39:43 +0000 (-0400)
Subject: Add a much-needed convenience accessor for max payload len.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8ac3efda2fb27271307421d008f64787fdb12c8c;p=thirdparty%2Ftor.git

Add a much-needed convenience accessor for max payload len.
---

diff --git a/src/core/or/relay_msg.c b/src/core/or/relay_msg.c
index 8abdc2182d..d5634a304b 100644
--- a/src/core/or/relay_msg.c
+++ b/src/core/or/relay_msg.c
@@ -300,3 +300,15 @@ circuit_get_relay_format(const circuit_t *circ, const crypt_path_t *cpath)
     tor_assert_unreached();
   }
 }
+
+/**
+ * Return the maximum relay payload that can be sent to the chosen
+ * point, with the specified command.
+ */
+size_t
+circuit_get_max_relay_payload(const circuit_t *circ, const crypt_path_t *cpath,
+                              uint8_t relay_command)
+{
+  relay_cell_fmt_t fmt = circuit_get_relay_format(circ, cpath);
+  return relay_cell_max_payload_size(fmt, relay_command);
+}
diff --git a/src/core/or/relay_msg.h b/src/core/or/relay_msg.h
index 0bc98f9f3c..941c8896ef 100644
--- a/src/core/or/relay_msg.h
+++ b/src/core/or/relay_msg.h
@@ -34,6 +34,9 @@ relay_msg_t *relay_msg_decode_cell(
 /* Getters */
 relay_cell_fmt_t circuit_get_relay_format(const circuit_t *circ,
                                           const crypt_path_t *cpath);
+size_t circuit_get_max_relay_payload(const circuit_t *circ,
+                              const crypt_path_t *cpath,
+                              uint8_t relay_command);
 
 /*
  * NOTE: The following are inlined for performance reasons. These values are