Return S2N_ERR_CIPHER_TYPE for unknown types

Not an error case that's being exercised right now, but we need to
have s2n_errno set for all -1 return values.

Author: raycoll

error/s2n_errno.c

@@ -107,6 +107,7 @@ struct s2n_error_translation EN[] = {
     {S2N_ERR_NON_EMPTY_RENEGOTIATION_INFO, "renegotiation_info should be empty"},
     {S2N_ERR_SEND_SIZE, "Retried s2n_send() size is invalid"},
     {S2N_ERR_PRIVATE_KEY_CHECK, "Error calling RSA_check_key()"},
+    {S2N_ERR_CIPHER_TYPE, "Unknown cipher type used"},
 };
 
 const char *s2n_strerror(int error, const char *lang)

error/s2n_errno.h

@@ -105,6 +105,7 @@ typedef enum {
     S2N_ERR_DRBG,
     S2N_ERR_DRBG_REQUEST_SIZE,
     S2N_ERR_PRIVATE_KEY_CHECK,
+    S2N_ERR_CIPHER_TYPE,
     /* S2N_ERR_T_USAGE */
     S2N_ERR_NO_ALERT = S2N_ERR_T_USAGE_START,
     S2N_ERR_CLIENT_MODE,

tls/s2n_record_read.c

@@ -210,7 +210,7 @@ int s2n_record_parse(struct s2n_connection *conn)
         GUARD(cipher_suite->cipher->io.aead.decrypt(session_key, &iv, &aad, &en, &en));
         break;
     default:
-        return -1;
+        S2N_ERROR(S2N_ERR_CIPHER_TYPE);
         break;
     }
 

tls/s2n_record_write.c

@@ -250,7 +250,7 @@ int s2n_record_write(struct s2n_connection *conn, uint8_t content_type, struct s
         GUARD(cipher_suite->cipher->io.aead.encrypt(session_key, &iv, &aad, &en, &en));
         break;
     default:
-        return -1;
+        S2N_ERROR(S2N_ERR_CIPHER_TYPE);
         break;
     }