lakers-c: Manually reconstruct the buffer size selection for C

Workaround-For: mozilla/cbindgen#1018

shared/cbindgen.toml

@@ -7,12 +7,83 @@ header = """
  * ================================================================================================
  *  WARNING: This file is automatically generated by cbindgen. Manual edits are likely to be lost.
  * ================================================================================================
- */"""
-include_guard = "LAKERS_SHARED_H"
+ */
+
+#ifndef LAKERS_SHARED_H
+#define LAKERS_SHARED_H
+
+/* Manually implemented to work around https://github.com/mozilla/cbindgen/issues/1018 */
+
+#if defined(_MAX_MESSAGE_SIZE_LEN_1024)
+#define MAX_MESSAGE_SIZE_LEN 1024
+#elif defined(_MAX_MESSAGE_SIZE_LEN_512)
+#define MAX_MESSAGE_SIZE_LEN 512
+#elif defined(_MAX_MESSAGE_SIZE_LEN_448)
+#define MAX_MESSAGE_SIZE_LEN 448
+#elif defined(_MAX_MESSAGE_SIZE_LEN_384)
+#define MAX_MESSAGE_SIZE_LEN 384
+#else
+#define MAX_MESSAGE_SIZE_LEN 256 + 64
+#endif
+
+#if defined(_MAX_KDF_CONTENT_LEN_1024)
+#define MAX_KDF_CONTEXT_LEN 1024
+#elif defined(_MAX_KDF_CONTENT_LEN_512)
+#define MAX_KDF_CONTEXT_LEN 512
+#elif defined(_MAX_KDF_CONTENT_LEN_448)
+#define MAX_KDF_CONTEXT_LEN 448
+#elif defined(_MAX_KDF_CONTENT_LEN_384)
+#define MAX_KDF_CONTEXT_LEN 384
+#elif defined(_MAX_KDF_CONTENT_LEN_320)
+#define MAX_KDF_CONTEXT_LEN 320
+#else
+#define MAX_KDF_CONTEXT_LEN 256
+#endif
+
+#if defined(_MAX_KDF_CONTENT_LEN_1024)
+#define MAX_BUFFER_LEN 1024
+#elif defined(_MAX_KDF_CONTENT_LEN_512)
+#define MAX_BUFFER_LEN 512
+#elif defined(_MAX_KDF_CONTENT_LEN_448)
+#define MAX_BUFFER_LEN 448
+#elif defined(_MAX_KDF_CONTENT_LEN_384)
+#define MAX_BUFFER_LEN 384
+#else
+#define MAX_BUFFER_LEN 256 + 64
+#endif
+
+#if defined(_MAX_CONNID_ENCODED_LEN_24)
+#define MAX_CONNID_ENCODED_LEN 24
+#else
+#define MAX_CONNID_ENCODED_LEN 8
+#endif
+"""
+trailer = """
+#endif  /* LAKERS_SHARED_H */
+"""
+# Done manually so that the manual parts of the MAX_MESSAGE_SIZE_LEN_xxx etc
+# features can be placed after the include guard:
+# include_guard = "LAKERS_SHARED_H"
 cpp_compat = true
 
 [defines]
 "feature = large_buffers" = "LARGE_BUFFERS"
+"feature = max_message_size_len_256" = "_MAX_MESSAGE_SIZE_LEN_256"
+"feature = max_message_size_len_320" = "_MAX_MESSAGE_SIZE_LEN_320"
+"feature = max_message_size_len_384" = "_MAX_MESSAGE_SIZE_LEN_384"
+"feature = max_message_size_len_448" = "_MAX_MESSAGE_SIZE_LEN_448"
+"feature = max_message_size_len_512" = "_MAX_MESSAGE_SIZE_LEN_512"
+"feature = max_message_size_len_1024" = "_MAX_MESSAGE_SIZE_LEN_1024"
+"feature = max_kdf_content_len_320" = "_MAX_KDF_CONTENT_LEN_320"
+"feature = max_kdf_content_len_384" = "_MAX_KDF_CONTENT_LEN_384"
+"feature = max_kdf_content_len_448" = "_MAX_KDF_CONTENT_LEN_448"
+"feature = max_kdf_content_len_512" = "_MAX_KDF_CONTENT_LEN_512"
+"feature = max_kdf_content_len_1024" = "_MAX_KDF_CONTENT_LEN_1024"
+"feature = max_buffer_len_384" = "_MAX_BUFFER_LEN_384"
+"feature = max_buffer_len_448" = "_MAX_BUFFER_LEN_448"
+"feature = max_buffer_len_512" = "_MAX_BUFFER_LEN_512"
+"feature = max_buffer_len_1024" = "_MAX_BUFFER_LEN_1024"
+"feature = max_connid_encoded_len_24" = "_MAX_CONNID_ENCODED_LEN_24"
 
 [export]
 include = [

shared/src/lib.rs

@@ -32,6 +32,7 @@ use pyo3::prelude::*;
 #[cfg(feature = "python-bindings")]
 mod python_bindings;
 
+// When changing this, beware that it is re-implemented in cbindgen.toml
 pub const MAX_MESSAGE_SIZE_LEN: usize = if cfg!(feature = "max_message_size_len_1024") {
     1024
 } else if cfg!(feature = "max_message_size_len_512") {
@@ -64,6 +65,8 @@ pub const MAC_LENGTH_3: usize = MAC_LENGTH_2;
 pub const ENCODED_VOUCHER_LEN: usize = 1 + MAC_LENGTH; // 1 byte for the length of the bstr-encoded voucher
 
 // maximum supported length of connection identifier for R
+//
+// When changing this, beware that it is re-implemented in cbindgen.toml
 pub const MAX_KDF_CONTEXT_LEN: usize = if cfg!(feature = "max_kdf_content_len_1024") {
     1024
 } else if cfg!(feature = "max_kdf_content_len_512") {
@@ -78,6 +81,8 @@ pub const MAX_KDF_CONTEXT_LEN: usize = if cfg!(feature = "max_kdf_content_len_10
     256
 };
 pub const MAX_KDF_LABEL_LEN: usize = 15; // for "KEYSTREAM_2"
+
+// When changing this, beware that it is re-implemented in cbindgen.toml
 pub const MAX_BUFFER_LEN: usize = if cfg!(feature = "max_buffer_len_1024") {
     1024
 } else if cfg!(feature = "max_buffer_len_512") {
@@ -121,6 +126,8 @@ pub const MAX_EAD_SIZE_LEN: usize = 64;
 /// This length includes the leading CBOR encoding byte(s).
 // Note that when implementing larger sizes than 24, the encoding will need to use actual CBOR
 // rather than masking a known short length into a byte.
+//
+// When changing this, beware that it is re-implemented in cbindgen.toml
 const MAX_CONNID_ENCODED_LEN: usize = if cfg!(feature = "max_connid_encoded_len_24") {
     24
 } else {