transport: provide a way to get the callbacks

libgit2 implementations of smart subtransports can simply reach through
the structure, but external implementors cannot.

Add these two functions as a way for the smart subtransports to get the
callbacks as set by the user.

include/git2/sys/transport.h

@@ -211,6 +211,28 @@ GIT_EXTERN(int) git_transport_smart(
 	git_remote *owner,
 	/* (git_smart_subtransport_definition *) */ void *payload);
 
+/**
+ * Call the certificate check for this transport.
+ *
+ * @param transport a smart transport
+ * @param cert the certificate to pass to the caller
+ * @param valid whether we believe the certificate is valid
+ * @param hostname the hostname we connected to
+ * @return the return value of the callback
+ */
+GIT_EXTERN(int) git_transport_smart_certificate_check(git_transport *transport, git_cert *cert, int valid, const char *hostname);
+
+/**
+ * Call the credentials callback for this transport
+ *
+ * @param out the pointer where the creds are to be stored
+ * @param transport a smart transport
+ * @param user the user we saw on the url (if any)
+ * @param methods available methods for authentication
+ * @return the return value of the callback
+ */
+GIT_EXTERN(int) git_transport_smart_credentials(git_cred **out, git_transport *transport, const char *user, int methods);
+
 /*
  *** End of base transport interface ***
  *** Begin interface for subtransports for the smart transport ***

src/transports/smart.c

@@ -372,6 +372,20 @@ static int ref_name_cmp(const void *a, const void *b)
 	return strcmp(ref_a->head.name, ref_b->head.name);
 }
 
+int git_transport_smart_certificate_check(git_transport *transport, git_cert *cert, int valid, const char *hostname)
+{
+	transport_smart *t = (transport_smart *)transport;
+
+	return t->certificate_check_cb(cert, valid, hostname, t->message_cb_payload);
+}
+
+int git_transport_smart_credentials(git_cred **out, git_transport *transport, const char *user, int methods)
+{
+	transport_smart *t = (transport_smart *)transport;
+
+	return t->cred_acquire_cb(out, t->url, user, methods, t->cred_acquire_payload);
+}
+
 int git_transport_smart(git_transport **out, git_remote *owner, void *param)
 {
 	transport_smart *t;