Merge pull request #835 from Ralith/stateless

[WIP] Expose bindings needed for TLS1.3 stateless handshakes

4 files changed, 142 insertions, 0 deletions

diff --git a/openssl-sys/src/lib.rs b/openssl-sys/src/lib.rs
index 7f3af1d7..77f69188 100644
--- a/openssl-sys/src/lib.rs
+++ b/openssl-sys/src/lib.rs
@@ -18,6 +18,11 @@ mod ossl110;
 #[cfg(ossl110)]
 pub use ossl110::*;
 
+#[cfg(ossl111)]
+mod ossl111;
+#[cfg(ossl111)]
+pub use ossl111::*;
+
 #[cfg(libressl)]
 mod libressl;
 #[cfg(libressl)]
@@ -1430,6 +1435,8 @@ pub const GEN_URI: c_int = 6;
 pub const GEN_IPADD: c_int = 7;
 pub const GEN_RID: c_int = 8;
 
+pub const DTLS1_COOKIE_LENGTH: c_uint = 256;
+
 // macros
 pub unsafe fn BIO_get_mem_data(b: *mut BIO, pp: *mut *mut c_char) -> c_long {
     BIO_ctrl(b, BIO_CTRL_INFO, 0, pp as *mut c_void)
@@ -2762,4 +2769,33 @@ extern "C" {
     pub fn FIPS_mode_set(onoff: c_int) -> c_int;
     #[cfg(not(libressl))]
     pub fn FIPS_mode() -> c_int;
+
+    pub fn SSL_CTX_set_cookie_generate_cb(
+        s: *mut SSL_CTX,
+        cb: Option<extern "C" fn(
+            ssl: *mut SSL,
+            cookie: *mut c_uchar,
+            cookie_len: *mut c_uint
+        ) -> c_int>
+    );
+
+    #[cfg(ossl110)]
+    pub fn SSL_CTX_set_cookie_verify_cb(
+        s: *mut SSL_CTX,
+        cb: Option<extern "C" fn(
+            ssl: *mut SSL,
+            cookie: *const c_uchar,
+            cookie_len: c_uint
+        ) -> c_int>
+    );
+
+    #[cfg(not(ossl110))]
+    pub fn SSL_CTX_set_cookie_verify_cb(
+        s: *mut SSL_CTX,
+        cb: Option<extern "C" fn(
+            ssl: *mut SSL,
+            cookie: *mut c_uchar,
+            cookie_len: c_uint
+        ) -> c_int>
+    );
 }
diff --git a/openssl-sys/src/ossl111.rs b/openssl-sys/src/ossl111.rs
new file mode 100644
index 00000000..c22d506c
--- /dev/null
+++ b/openssl-sys/src/ossl111.rs
@@ -0,0 +1,11 @@
+use libc::{c_int, c_ulong};
+
+use ossl110::*;
+
+pub const SSL_COOKIE_LENGTH: c_int = 255;
+
+pub const SSL_OP_ENABLE_MIDDLEBOX_COMPAT: c_ulong = 0x00100000;
+
+extern "C" {
+    pub fn SSL_stateless(s: *mut SSL) -> c_int;
+}
diff --git a/openssl/src/ssl/callbacks.rs b/openssl/src/ssl/callbacks.rs
index c06d32a0..424bdc1a 100644
--- a/openssl/src/ssl/callbacks.rs
+++ b/openssl/src/ssl/callbacks.rs
@@ -361,3 +361,53 @@ where
 
     callback(ssl, line);
 }
+
+pub extern "C" fn raw_cookie_generate<F>(
+    ssl: *mut ffi::SSL,
+    cookie: *mut c_uchar,
+    cookie_len: *mut c_uint
+) -> c_int
+where
+    F: Fn(&mut SslRef, &mut [u8]) -> Result<usize, ErrorStack> + 'static + Sync + Send
+{
+    unsafe {
+        let ssl_ctx = ffi::SSL_get_SSL_CTX(ssl as *const _);
+        let callback = ffi::SSL_CTX_get_ex_data(ssl_ctx, get_callback_idx::<F>());
+        let ssl = SslRef::from_ptr_mut(ssl);
+        let callback = &*(callback as *mut F);
+        // We subtract 1 from DTLS1_COOKIE_LENGTH as the ostensible value, 256, is erroneous but retained for
+        // compatibility. See comments in dtls1.h.
+        let slice = slice::from_raw_parts_mut(cookie as *mut u8, ffi::DTLS1_COOKIE_LENGTH as usize - 1);
+        match callback(ssl, slice) {
+            Ok(len) => {
+                *cookie_len = len as c_uint;
+                1
+            }
+            Err(_) => 0,
+        }
+    }
+}
+
+#[cfg(ossl110)]
+type CookiePtr = *const c_uchar;
+
+#[cfg(not(ossl110))]
+type CookiePtr = *mut c_uchar;
+
+pub extern "C" fn raw_cookie_verify<F>(
+    ssl: *mut ffi::SSL,
+    cookie: CookiePtr,
+    cookie_len: c_uint
+) -> c_int
+where
+    F: Fn(&mut SslRef, &[u8]) -> bool + 'static + Sync + Send
+{
+    unsafe {
+        let ssl_ctx = ffi::SSL_get_SSL_CTX(ssl as *const _);
+        let callback = ffi::SSL_CTX_get_ex_data(ssl_ctx, get_callback_idx::<F>());
+        let ssl = SslRef::from_ptr_mut(ssl);
+        let callback = &*(callback as *mut F);
+        let slice = slice::from_raw_parts(cookie as *const c_uchar as *const u8, cookie_len as usize);
+        callback(ssl, slice) as c_int
+    }
+}
diff --git a/openssl/src/ssl/mod.rs b/openssl/src/ssl/mod.rs
index fb7db988..91b97818 100644
--- a/openssl/src/ssl/mod.rs
+++ b/openssl/src/ssl/mod.rs
@@ -1311,6 +1311,51 @@ impl SslContextBuilder {
         }
     }
 
+    /// Sets the callback for generating an application cookie for stateless handshakes.
+    ///
+    /// The callback will be called with the SSL context and a slice into which the cookie
+    /// should be written. The callback should return the number of bytes written.
+    ///
+    /// This corresponds to `SSL_CTX_set_cookie_generate_cb`.
+    pub fn set_cookie_generate_cb<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &mut [u8]) -> Result<usize, ErrorStack> + 'static + Sync + Send
+    {
+        unsafe {
+            let callback = Box::new(callback);
+            ffi::SSL_CTX_set_ex_data(
+                self.as_ptr(),
+                get_callback_idx::<F>(),
+                mem::transmute(callback),
+            );
+            ffi::SSL_CTX_set_cookie_generate_cb(self.as_ptr(), Some(raw_cookie_generate::<F>))
+        }
+    }
+
+    /// Sets the callback for verifying an application cookie for stateless handshakes.
+    ///
+    /// The callback will be called with the SSL context and the cookie supplied by the
+    /// client. It should return true if and only if the cookie is valid.
+    ///
+    /// Note that the OpenSSL implementation independently verifies the integrity of
+    /// application cookies using an HMAC before invoking the supplied callback.
+    ///
+    /// This corresponds to `SSL_CTX_set_cookie_verify_cb`.
+    pub fn set_cookie_verify_cb<F>(&mut self, callback: F)
+    where
+        F: Fn(&mut SslRef, &[u8]) -> bool + 'static + Sync + Send
+    {
+        unsafe {
+            let callback = Box::new(callback);
+            ffi::SSL_CTX_set_ex_data(
+                self.as_ptr(),
+                get_callback_idx::<F>(),
+                mem::transmute(callback),
+            );
+            ffi::SSL_CTX_set_cookie_verify_cb(self.as_ptr(), Some(raw_cookie_verify::<F>))
+        }
+    }
+
     /// Sets the extra data at the specified index.
     ///
     /// This can be used to provide data to callbacks registered with the context. Use the