From 10db4811a3baea65021eec40dab6243f49bfd79f Mon Sep 17 00:00:00 2001
From: chrysn <chrysn@fsfe.org>
Date: Wed, 22 Jan 2025 14:24:51 +0100
Subject: [PATCH] shared: Replace quadruple_sizes feature with large_buffers

---
 lakers-python/Cargo.toml |  2 +-
 shared/Cargo.toml        | 28 +++++++++++++++-------------
 shared/cbindgen.toml     |  2 +-
 shared/src/lib.rs        | 16 +++-------------
 4 files changed, 20 insertions(+), 28 deletions(-)

diff --git a/lakers-python/Cargo.toml b/lakers-python/Cargo.toml
index 9c155478..7cc1dbd4 100644
--- a/lakers-python/Cargo.toml
+++ b/lakers-python/Cargo.toml
@@ -11,7 +11,7 @@ license.workspace = true
 pyo3 = { version = "0.22", features = ["extension-module"] }
 lakers = { package = "lakers", path = "../lib", default-features = false, features = [ "log" ] }
 lakers-ead-authz = { path = "../ead/lakers-ead-authz", features = [ "log" ] }
-lakers-shared = { path = "../shared", features = ["python-bindings", "quadruple_sizes"] }
+lakers-shared = { path = "../shared", features = ["python-bindings", "large_buffers"] }
 lakers-crypto = { path = "../crypto", default-features = false, features = ["rustcrypto"] }
 log = "0.4"
 pyo3-log = "0.11.0"
diff --git a/shared/Cargo.toml b/shared/Cargo.toml
index 514e91c9..da67fe4f 100644
--- a/shared/Cargo.toml
+++ b/shared/Cargo.toml
@@ -26,19 +26,21 @@ rstest = "0.21.0"
 default = [  ]
 python-bindings = ["pyo3", "hex"]
 
-## For all arbitrarily limited buffers, pick 4x the current default.
+## For all arbitrarily limited buffers, pick the maximum.
 ##
-## On the long run, this might be replaced with a more fine-grained feature set
-## picking the minimum size of all the items, or even an option to generalize,
-## but this provides an easy way to allow unconstrained systems to stomach
-## larger sizes (especially for experimentation) without making sizes explode
-## on embedded.
-quadruple_sizes = []
+## This provides an easy way to allow unconstrained systems to stomach larger
+## sizes (especially for experimentation).
+large_buffers = [
+    "max_message_size_len_1024",
+    "max_kdf_content_len_1024",
+    "max_buffer_len_1024",
+    "max_connid_encoded_len_24",
+]
 
 ## Precise control of `MAX_MESSAGE_SIZE_LEN`.
 ##
-## If any of those is set, they override the default of 192 (as well as
-## `quadruple_sizes`). If multiple are set, the highest wins.
+## If any of those is set, they override the default of 192. If multiple are
+## set, the highest wins.
 
 max_message_size_len_256 = []
 max_message_size_len_320 = []
@@ -49,8 +51,8 @@ max_message_size_len_1024 = []
 
 ## Precise control of `MAX_KDF_CONTENT_LEN`.
 ##
-## If any of those is set, they override the default of 256 (as well as
-## `quadruple_sizes`). If multiple are set, the highest wins.
+## If any of those is set, they override the default of 256. If multiple are
+## set, the highest wins.
 
 max_kdf_content_len_320 = []
 max_kdf_content_len_384 = []
@@ -60,8 +62,8 @@ max_kdf_content_len_1024 = []
 
 ## Precise control of `MAX_BUFFER_LEN`.
 ##
-## If any of those is set, they override the default of 320 (as well as
-## `quadruple_sizes`). If multiple are set, the highest wins.
+## If any of those is set, they override the default of 320. If multiple are
+## set, the highest wins.
 
 max_buffer_len_384 = []
 max_buffer_len_448 = []
diff --git a/shared/cbindgen.toml b/shared/cbindgen.toml
index ff11b562..8b6f2b8f 100644
--- a/shared/cbindgen.toml
+++ b/shared/cbindgen.toml
@@ -12,7 +12,7 @@ include_guard = "LAKERS_SHARED_H"
 cpp_compat = true
 
 [defines]
-"feature = quadruple_sizes" = "QUADRUPLE_SIZES"
+"feature = large_buffers" = "LARGE_BUFFERS"
 
 [export]
 include = [
diff --git a/shared/src/lib.rs b/shared/src/lib.rs
index 676c98db..01a4f7ed 100644
--- a/shared/src/lib.rs
+++ b/shared/src/lib.rs
@@ -32,16 +32,6 @@ use pyo3::prelude::*;
 #[cfg(feature = "python-bindings")]
 mod python_bindings;
 
-/// Configured upscaling applied to fixed-size buffers
-///
-/// Do not rely on this: It is only pub because cbindgen needs it.
-#[cfg(not(feature = "quadruple_sizes"))]
-#[doc(hidden)]
-pub const SCALE_FACTOR: usize = 1;
-#[cfg(feature = "quadruple_sizes")]
-#[doc(hidden)]
-pub const SCALE_FACTOR: usize = 4;
-
 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") {
@@ -56,7 +46,7 @@ pub const MAX_MESSAGE_SIZE_LEN: usize = if cfg!(feature = "max_message_size_len_
     256
 } else {
     // need 128 to handle EAD fields, and 192 for the EAD_1 voucher
-    SCALE_FACTOR * (128 + 64)
+    128 + 64
 };
 
 pub const ID_CRED_LEN: usize = 4;
@@ -85,7 +75,7 @@ pub const MAX_KDF_CONTEXT_LEN: usize = if cfg!(feature = "max_kdf_content_len_10
 } else if cfg!(feature = "max_kdf_content_len_320") {
     320
 } else {
-    SCALE_FACTOR * 256
+    256
 };
 pub const MAX_KDF_LABEL_LEN: usize = 15; // for "KEYSTREAM_2"
 pub const MAX_BUFFER_LEN: usize = if cfg!(feature = "max_buffer_len_1024") {
@@ -97,7 +87,7 @@ pub const MAX_BUFFER_LEN: usize = if cfg!(feature = "max_buffer_len_1024") {
 } else if cfg!(feature = "max_buffer_len_384") {
     384
 } else {
-    SCALE_FACTOR * 256 + 64
+    256 + 64
 };
 pub const CBOR_BYTE_STRING: u8 = 0x58u8;
 pub const CBOR_TEXT_STRING: u8 = 0x78u8;