reused evp context

transform_aes.c

@@ -43,6 +43,8 @@
 typedef unsigned char n2n_aes_ivec_t[N2N_AES_IVEC_SIZE];
 
 typedef struct transop_aes {
+    EVP_CIPHER_CTX	*enc_ctx;	/* openssl's reusable evp_* encryption context */
+    EVP_CIPHER_CTX	*dec_ctx;	/* openssl's reusable evp_* decryption context */
     const EVP_CIPHER	*cipher;	/* cipher to use: e.g. EVP_aes_128_cbc */
     uint8_t  		key[32];	/* the pure key data for payload encryption & decryption */
     AES_KEY             iv_enc_key;     /* key used to encrypt the IV */
@@ -52,6 +54,9 @@ typedef struct transop_aes {
 static int transop_deinit_aes(n2n_trans_op_t *arg) {
     transop_aes_t *priv = (transop_aes_t *)arg->priv;
 
+    EVP_CIPHER_CTX_free(priv->enc_ctx);
+    EVP_CIPHER_CTX_free(priv->dec_ctx);
+
     if(priv)
         free(priv);
 
@@ -145,10 +150,9 @@ static int transop_encode_aes( n2n_trans_op_t * arg,
 
             set_aes_cbc_iv(priv, enc_ivec, iv_seed);
 
-    	    EVP_CIPHER_CTX *ctx;
+    	    EVP_CIPHER_CTX *ctx = priv->enc_ctx;
 	    int evp_len;
 	    int evp_ciphertext_len;
-	    if ((ctx = EVP_CIPHER_CTX_new())) {
 	    if (1 == EVP_EncryptInit_ex(ctx, priv->cipher, NULL, priv->key, enc_ivec)) {
 		if (1 == EVP_CIPHER_CTX_set_padding(ctx, 0)) {
 		    if (1 == EVP_EncryptUpdate(ctx, outbuf + TRANSOP_AES_PREAMBLE_SIZE, &evp_len, assembly, len2)) {
@@ -166,9 +170,7 @@ static int transop_encode_aes( n2n_trans_op_t * arg,
 		    traceEvent(TRACE_ERROR, "encode_aes openssl padding setup: %s\n", openssl_err_as_string());
 	    } else
 	        traceEvent(TRACE_ERROR, "encode_aes openssl init: %s\n", openssl_err_as_string());
-            } else
-	        traceEvent(TRACE_ERROR, "encode_aes openssl context creation: %s\n", openssl_err_as_string());
-	    EVP_CIPHER_CTX_free(ctx);
+	    EVP_CIPHER_CTX_reset(ctx);
 
             len2 += TRANSOP_AES_PREAMBLE_SIZE; /* size of data carried in UDP. */
         } else
@@ -216,10 +218,9 @@ static int transop_decode_aes( n2n_trans_op_t * arg,
 
                 set_aes_cbc_iv(priv, dec_ivec, iv_seed);
 
-	        EVP_CIPHER_CTX *ctx;
+	        EVP_CIPHER_CTX *ctx = priv->dec_ctx;
 	        int evp_len;
 	        int evp_plaintext_len;
-	        if ((ctx = EVP_CIPHER_CTX_new())) {
 	        if (1 == EVP_DecryptInit_ex(ctx, priv->cipher, NULL, priv->key, dec_ivec)) {
 		    if (1 == EVP_CIPHER_CTX_set_padding(ctx, 0)) {
 		        if (1 == EVP_DecryptUpdate(ctx, assembly, &evp_len, inbuf + TRANSOP_AES_PREAMBLE_SIZE, len)) {
@@ -237,9 +238,7 @@ static int transop_decode_aes( n2n_trans_op_t * arg,
 		        traceEvent(TRACE_ERROR, "decode_aes openssl padding setup: %s\n", openssl_err_as_string());
 		} else
 	            traceEvent(TRACE_ERROR, "decode_aes openssl init: %s\n", openssl_err_as_string());
-	        } else
-	            traceEvent(TRACE_ERROR, "decode_aes openssl context creation: %s\n", openssl_err_as_string());
-	        EVP_CIPHER_CTX_free(ctx);
+		EVP_CIPHER_CTX_reset(ctx);
 
                 /* last byte is how much was padding: max value should be
                  * AES_BLOCKSIZE-1 */
@@ -369,7 +368,17 @@ int n2n_transop_aes_cbc_init(const n2n_edge_conf_t *conf, n2n_trans_op_t *ttt) {
   }
   ttt->priv = priv;
 
-  /* Setup the key */
+  /* Setup openssl's reusable evp_* contexts for encryption and decryption*/
+  if (!(priv->enc_ctx = EVP_CIPHER_CTX_new())) {
+    traceEvent(TRACE_ERROR, "openssl's evp_* encryption context creation: %s\n", openssl_err_as_string());
+    return(-1);
+  }
+  if (!(priv->dec_ctx = EVP_CIPHER_CTX_new())) {
+    traceEvent(TRACE_ERROR, "openssl's evp_* decryption context creation: %s\n", openssl_err_as_string());
+    return(-1);
+  }
+
+  /* Setup the cipher and key */
   return(setup_aes_key(priv, encrypt_key, encrypt_key_len));
 }