packet: Introduce a new function to access crypto

And remove most of the direct access to the structure throughout the code

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Daiki Ueno <dueno@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

include/libssh/crypto.h

@@ -136,6 +136,7 @@ struct ssh_crypto_struct {
     char *kex_methods[SSH_KEX_METHODS];
     enum ssh_key_exchange_e kex_type;
     enum ssh_mac_e mac_type; /* Mac operations to use for key gen */
+    enum ssh_crypto_direction_e used; /* Is this crypto still used for either of directions? */
 };
 
 struct ssh_cipher_struct {

include/libssh/packet.h

@@ -83,5 +83,7 @@ unsigned char *ssh_packet_encrypt(ssh_session session,
                                   unsigned int len);
 int ssh_packet_hmac_verify(ssh_session session,ssh_buffer buffer,
                            unsigned char *mac, enum ssh_hmac_e type);
+struct ssh_crypto_struct *ssh_packet_get_current_crypto(ssh_session session,
+        enum ssh_crypto_direction_e direction);
 
 #endif /* PACKET_H_ */

include/libssh/wrapper.h

@@ -61,6 +61,12 @@ struct ssh_hmac_struct {
   enum ssh_hmac_e hmac_type;
 };
 
+enum ssh_crypto_direction_e {
+    SSH_DIRECTION_IN = 1,
+    SSH_DIRECTION_OUT = 2,
+    SSH_DIRECTION_BOTH = 3,
+};
+
 struct ssh_cipher_struct;
 
 typedef struct ssh_mac_ctx_struct *ssh_mac_ctx;