feat(boring): Add add_cert_compression_alg support (#44)

Cargo.toml

@@ -39,3 +39,6 @@ antidote = "1.0.0"
 linked_hash_set = "0.1"
 openssl-macros = "0.1.1"
 autocfg = "1.3.0"
+brotli = "7"
+flate2 = "1"
+zstd = "0.13"

boring/Cargo.toml

@@ -64,12 +64,18 @@ kx-client-pq-preferred = ["kx-safe-default", "kx-client-pq-supported"]
 # Implies "kx-safe-default".
 kx-client-nist-required = ["kx-safe-default"]
 
+# Certificate compression
+cert-compression = ["flate2", "brotli", "zstd"]
+
 [dependencies]
 bitflags = { workspace = true }
 foreign-types = { workspace = true }
 openssl-macros = { workspace = true }
 libc = { workspace = true }
 boring-sys = { workspace = true }
+brotli = { workspace = true, optional = true }
+flate2 = { workspace = true, optional = true }
+zstd = { workspace = true, optional = true }
 
 [dev-dependencies]
 hex = { workspace = true }

boring/src/ssl/cert_compression.rs

@@ -0,0 +1,190 @@
+use boring_sys as ffi;
+use std::{io::Read, slice};
+
+/// IANA assigned identifier of compression algorithm.
+/// See https://www.rfc-editor.org/rfc/rfc8879.html#name-compression-algorithms
+#[repr(u16)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum CertCompressionAlgorithm {
+    /// The Brotli compression algorithm.
+    Brotli = ffi::TLSEXT_cert_compression_brotli as _,
+    /// The zlib compression algorithm.
+    Zlib = ffi::TLSEXT_cert_compression_zlib as _,
+    /// The Zstandard compression algorithm.
+    Zstd = ffi::TLSEXT_cert_compression_zstd as _,
+}
+
+impl CertCompressionAlgorithm {
+    /// Returns the compression function for the algorithm.
+    pub(crate) fn compression_fn(&self) -> ffi::ssl_cert_compression_func_t {
+        match &self {
+            Self::Brotli => Some(brotli_compressor),
+            Self::Zlib => Some(zlib_compressor),
+            Self::Zstd => Some(zstd_compressor),
+        }
+    }
+
+    /// Returns the decompression function for the algorithm.
+    pub(crate) fn decompression_fn(&self) -> ffi::ssl_cert_decompression_func_t {
+        match &self {
+            Self::Brotli => Some(brotli_decompressor),
+            Self::Zlib => Some(zlib_decompressor),
+            Self::Zstd => Some(zstd_decompressor),
+        }
+    }
+}
+
+extern "C" fn brotli_compressor(
+    _ssl: *mut ffi::SSL,
+    buffer: *mut ffi::CBB,
+    in_: *const u8,
+    in_len: usize,
+) -> ::std::os::raw::c_int {
+    let mut uncompressed = unsafe { slice::from_raw_parts(in_, in_len) };
+    let mut compressed = Vec::new();
+
+    let params = brotli::enc::encode::BrotliEncoderInitParams();
+
+    if brotli::BrotliCompress(&mut uncompressed, &mut compressed, &params).is_err() {
+        return 0;
+    }
+
+    unsafe { ffi::CBB_add_bytes(buffer, compressed.as_ptr(), compressed.len()) }
+}
+
+extern "C" fn zlib_compressor(
+    _ssl: *mut ffi::SSL,
+    out: *mut ffi::CBB,
+    in_: *const u8,
+    in_len: usize,
+) -> ::std::os::raw::c_int {
+    let mut uncompressed = unsafe { slice::from_raw_parts(in_, in_len) };
+    let mut compressed = Vec::new();
+
+    let params = flate2::Compression::default();
+
+    let mut encoder = flate2::bufread::ZlibEncoder::new(&mut uncompressed, params);
+    if encoder.read_to_end(&mut compressed).is_err() {
+        return 0;
+    }
+
+    unsafe { ffi::CBB_add_bytes(out, compressed.as_ptr(), compressed.len()) }
+}
+
+extern "C" fn zstd_compressor(
+    _ssl: *mut ffi::SSL,
+    out: *mut ffi::CBB,
+    in_: *const u8,
+    in_len: usize,
+) -> ::std::os::raw::c_int {
+    let mut uncompressed = unsafe { slice::from_raw_parts(in_, in_len) };
+
+    let compressed = if let Ok(compressed) = zstd::encode_all(&mut uncompressed, 3) {
+        compressed
+    } else {
+        return 0;
+    };
+
+    unsafe { ffi::CBB_add_bytes(out, compressed.as_ptr(), compressed.len()) }
+}
+
+extern "C" fn brotli_decompressor(
+    _ssl: *mut ffi::SSL,
+    buffer: *mut *mut ffi::CRYPTO_BUFFER,
+    uncompressed_len: usize,
+    in_: *const u8,
+    in_len: usize,
+) -> ::std::os::raw::c_int {
+    let compressed = unsafe { slice::from_raw_parts(in_, in_len) };
+    let mut uncompressed = Vec::with_capacity(uncompressed_len);
+
+    if brotli::BrotliDecompress(&mut &compressed[..], &mut uncompressed).is_err() {
+        return 0;
+    }
+
+    if uncompressed.len() != uncompressed_len {
+        return 0;
+    }
+
+    unsafe {
+        *buffer = ffi::CRYPTO_BUFFER_new(
+            uncompressed.as_ptr(),
+            uncompressed_len,
+            std::ptr::null_mut(),
+        );
+
+        if buffer.is_null() {
+            return 0;
+        }
+    }
+
+    1
+}
+
+extern "C" fn zlib_decompressor(
+    _ssl: *mut ffi::SSL,
+    buffer: *mut *mut ffi::CRYPTO_BUFFER,
+    uncompressed_len: usize,
+    in_: *const u8,
+    in_len: usize,
+) -> ::std::os::raw::c_int {
+    let mut compressed = unsafe { slice::from_raw_parts(in_, in_len) };
+    let mut uncompressed = Vec::with_capacity(uncompressed_len);
+
+    let mut decoder = flate2::bufread::ZlibDecoder::new(&mut compressed);
+    if decoder.read_to_end(&mut uncompressed).is_err() {
+        return 0;
+    }
+
+    if uncompressed.len() != uncompressed_len {
+        return 0;
+    }
+
+    unsafe {
+        *buffer = ffi::CRYPTO_BUFFER_new(
+            uncompressed.as_ptr(),
+            uncompressed_len,
+            std::ptr::null_mut(),
+        );
+
+        if buffer.is_null() {
+            return 0;
+        }
+    }
+
+    1
+}
+
+extern "C" fn zstd_decompressor(
+    _ssl: *mut ffi::SSL,
+    buffer: *mut *mut ffi::CRYPTO_BUFFER,
+    uncompressed_len: usize,
+    in_: *const u8,
+    in_len: usize,
+) -> ::std::os::raw::c_int {
+    let mut compressed = unsafe { slice::from_raw_parts(in_, in_len) };
+
+    let uncompressed = if let Ok(uncompressed) = zstd::decode_all(&mut compressed) {
+        uncompressed
+    } else {
+        return 0;
+    };
+
+    if uncompressed.len() != uncompressed_len {
+        return 0;
+    }
+
+    unsafe {
+        *buffer = ffi::CRYPTO_BUFFER_new(
+            uncompressed.as_ptr(),
+            uncompressed_len,
+            std::ptr::null_mut(),
+        );
+
+        if buffer.is_null() {
+            return 0;
+        }
+    }
+
+    1
+}

boring/src/ssl/mod.rs

@@ -101,6 +101,8 @@ pub use self::async_callbacks::{
     BoxCustomVerifyFuture, BoxGetSessionFinish, BoxGetSessionFuture, BoxPrivateKeyMethodFinish,
     BoxPrivateKeyMethodFuture, BoxSelectCertFinish, BoxSelectCertFuture, ExDataFuture,
 };
+#[cfg(feature = "cert-compression")]
+pub use self::cert_compression::CertCompressionAlgorithm;
 pub use self::connector::{
     ConnectConfiguration, SslAcceptor, SslAcceptorBuilder, SslConnector, SslConnectorBuilder,
 };
@@ -109,6 +111,8 @@ pub use self::error::{Error, ErrorCode, HandshakeError};
 mod async_callbacks;
 mod bio;
 mod callbacks;
+#[cfg(feature = "cert-compression")]
+mod cert_compression;
 mod connector;
 mod error;
 mod mut_only;
@@ -1353,6 +1357,24 @@ impl SslContextBuilder {
         unsafe { cvt(ffi::SSL_CTX_use_PrivateKey(self.as_ptr(), key.as_ptr())).map(|_| ()) }
     }
 
+    /// Sets whether a certificate compression algorithm should be used.
+    #[cfg(feature = "cert-compression")]
+    #[corresponds(SSL_CTX_add_cert_compression_alg)]
+    pub fn add_cert_compression_alg(
+        &mut self,
+        alg: CertCompressionAlgorithm,
+    ) -> Result<(), ErrorStack> {
+        unsafe {
+            cvt(ffi::SSL_CTX_add_cert_compression_alg(
+                self.as_ptr(),
+                alg as _,
+                alg.compression_fn(),
+                alg.decompression_fn(),
+            ))
+            .map(|_| ())
+        }
+    }
+
     /// Sets the list of supported ciphers for protocols before TLSv1.3.
     ///
     /// The `set_ciphersuites` method controls the cipher suites for TLSv1.3 in OpenSSL.