transport: see if cert/cred callbacks exist before calling them

Custom transports may want to ask libgit2 to invoke a configured
credential or certificate callback; however they likely do not know if a
callback was actually configured.  Return a sentinal value
(GIT_PASSTHROUGH) if there is no callback configured instead of crashing.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/transports/smart.c b/src/transports/smart.c
index e972d30ba..9fcbdcf21 100644
--- a/src/transports/smart.c
+++ b/src/transports/smart.c
@@ -481,6 +481,11 @@ int git_transport_smart_certificate_check(git_transport *transport, git_cert *ce
 {
 	transport_smart *t = (transport_smart *)transport;
 
+	assert(transport && cert && hostname);
+
+	if (!t->certificate_check_cb)
+		return GIT_PASSTHROUGH;
+
 	return t->certificate_check_cb(cert, valid, hostname, t->message_cb_payload);
 }
 
@@ -488,6 +493,11 @@ int git_transport_smart_credentials(git_cred **out, git_transport *transport, co
 {
 	transport_smart *t = (transport_smart *)transport;
 
+	assert(out && transport);
+
+	if (!t->cred_acquire_cb)
+		return GIT_PASSTHROUGH;
+
 	return t->cred_acquire_cb(out, t->url, user, methods, t->cred_acquire_payload);
 }