TLS1.3 Padding

Add padding callback for application control
Standard block_size callback
Documentation and tests included
Configuration file/s_client/s_srver option

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3130)

1 files changed, 61 insertions, 0 deletions

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index c59aa847e4..d1a1f027d9 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -571,6 +571,9 @@ SSL *SSL_new(SSL_CTX *ctx)
     s->msg_callback_arg = ctx->msg_callback_arg;
     s->verify_mode = ctx->verify_mode;
     s->not_resumable_session_cb = ctx->not_resumable_session_cb;
+    s->record_padding_cb = ctx->record_padding_cb;
+    s->record_padding_arg = ctx->record_padding_arg;
+    s->block_padding = ctx->block_padding;
     s->sid_ctx_length = ctx->sid_ctx_length;
     OPENSSL_assert(s->sid_ctx_length <= sizeof s->sid_ctx);
     memcpy(&s->sid_ctx, &ctx->sid_ctx, sizeof(s->sid_ctx));
@@ -3889,6 +3892,64 @@ void SSL_set_not_resumable_session_callback(SSL *ssl,
                       (void (*)(void))cb);
 }
 
+void SSL_CTX_set_record_padding_callback(SSL_CTX *ctx,
+                                         size_t (*cb) (SSL *ssl, int type,
+                                                       size_t len, void *arg))
+{
+    ctx->record_padding_cb = cb;
+}
+
+void SSL_CTX_set_record_padding_callback_arg(SSL_CTX *ctx, void *arg)
+{
+    ctx->record_padding_arg = arg;
+}
+
+void *SSL_CTX_get_record_padding_callback_arg(SSL_CTX *ctx)
+{
+    return ctx->record_padding_arg;
+}
+
+int SSL_CTX_set_block_padding(SSL_CTX *ctx, size_t block_size)
+{
+    /* block size of 0 or 1 is basically no padding */
+    if (block_size == 1)
+        ctx->block_padding = 0;
+    else if (block_size <= SSL3_RT_MAX_PLAIN_LENGTH)
+        ctx->block_padding = block_size;
+    else
+        return 0;
+    return 1;
+}
+
+void SSL_set_record_padding_callback(SSL *ssl,
+                                     size_t (*cb) (SSL *ssl, int type,
+                                                   size_t len, void *arg))
+{
+    ssl->record_padding_cb = cb;
+}
+
+void SSL_set_record_padding_callback_arg(SSL *ssl, void *arg)
+{
+    ssl->record_padding_arg = arg;
+}
+
+void *SSL_get_record_padding_callback_arg(SSL *ssl)
+{
+    return ssl->record_padding_arg;
+}
+
+int SSL_set_block_padding(SSL *ssl, size_t block_size)
+{
+    /* block size of 0 or 1 is basically no padding */
+    if (block_size == 1)
+        ssl->block_padding = 0;
+    else if (block_size <= SSL3_RT_MAX_PLAIN_LENGTH)
+        ssl->block_padding = block_size;
+    else
+        return 0;
+    return 1;
+}
+
 /*
  * Allocates new EVP_MD_CTX and sets pointer to it into given pointer
  * variable, freeing EVP_MD_CTX previously stored in that variable, if any.