shared: Extend size features to other buffers that are easily exceeded

shared/Cargo.toml

@@ -45,3 +45,22 @@ max_message_size_len_320 = []
 max_message_size_len_384 = []
 max_message_size_len_448 = []
 max_message_size_len_512 = []
+
+## 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.
+
+max_kdf_content_len_320 = []
+max_kdf_content_len_384 = []
+max_kdf_content_len_448 = []
+max_kdf_content_len_512 = []
+
+## 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.
+
+max_buffer_len_384 = []
+max_buffer_len_448 = []
+max_buffer_len_512 = []

shared/src/lib.rs

@@ -72,9 +72,27 @@ 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
-pub const MAX_KDF_CONTEXT_LEN: usize = SCALE_FACTOR * 256;
+pub const MAX_KDF_CONTEXT_LEN: usize = if cfg!(feature = "max_kdf_content_len_512") {
+    512
+} else if cfg!(feature = "max_kdf_content_len_448") {
+    448
+} else if cfg!(feature = "max_kdf_content_len_384") {
+    384
+} else if cfg!(feature = "max_kdf_content_len_320") {
+    320
+} else {
+    SCALE_FACTOR * 256
+};
 pub const MAX_KDF_LABEL_LEN: usize = 15; // for "KEYSTREAM_2"
-pub const MAX_BUFFER_LEN: usize = SCALE_FACTOR * 256 + 64;
+pub const MAX_BUFFER_LEN: usize = if cfg!(feature = "max_buffer_len_512") {
+    512
+} else if cfg!(feature = "max_buffer_len_448") {
+    448
+} else if cfg!(feature = "max_buffer_len_384") {
+    384
+} else {
+    SCALE_FACTOR * 256 + 64
+};
 pub const CBOR_BYTE_STRING: u8 = 0x58u8;
 pub const CBOR_TEXT_STRING: u8 = 0x78u8;
 pub const CBOR_UINT_1BYTE: u8 = 0x18u8;