thodg/libgit2

diff --git a/include/git2/transport.h b/include/git2/transport.h
index 81ebf4d..fe4883f 100644
--- a/include/git2/transport.h
+++ b/include/git2/transport.h
@@ -31,13 +31,16 @@ GIT_BEGIN_DECL
 /** Authentication type requested */
 typedef enum {
 	/* git_cred_userpass_plaintext */
-	GIT_CREDTYPE_USERPASS_PLAINTEXT =     (1u << 0),
+	GIT_CREDTYPE_USERPASS_PLAINTEXT = (1u << 0),
 
 	/* git_cred_ssh_key */
 	GIT_CREDTYPE_SSH_KEY = (1u << 1),
 
 	/* git_cred_ssh_custom */
-	GIT_CREDTYPE_SSH_CUSTOM =          (1u << 2),
+	GIT_CREDTYPE_SSH_CUSTOM = (1u << 2),
+
+	/* git_cred_default */
+	GIT_CREDTYPE_DEFAULT = (1u << 3),
 } git_credtype_t;
 
 /* The base structure for all credential types */
@@ -48,7 +51,7 @@ struct git_cred {
 	void (*free)(git_cred *cred);
 };
 
-/* A plaintext username and password */
+/** A plaintext username and password */
 typedef struct {
 	git_cred parent;
 	char *username;
@@ -84,6 +87,9 @@ typedef struct git_cred_ssh_custom {
 	void *sign_data;
 } git_cred_ssh_custom;
 
+/** A key for NTLM/Kerberos "default" credentials */
+typedef struct git_cred git_cred_default;
+
 /**
  * Check whether a credential object contains username information.
  *
@@ -151,6 +157,14 @@ GIT_EXTERN(int) git_cred_ssh_custom_new(
 	void *sign_data);
 
 /**
+ * Create a "default" credential usable for Negotiate mechanisms like NTLM
+ * or Kerberos authentication.
+ *
+ * @return 0 for success or an error code for failure
+ */
+GIT_EXTERN(int) git_cred_default_new(git_cred **out);
+
+/**
  * Signature of a function which acquires a credential object.
  *
  * @param cred The newly created credential object.
diff --git a/src/remote.c b/src/remote.c
index c0f35e5..d072eb9 100644
--- a/src/remote.c
+++ b/src/remote.c
@@ -82,29 +82,35 @@ static int ensure_remote_name_is_valid(const char *name)
 	return error;
 }
 
-static int get_check_cert(git_repository *repo)
+static int get_check_cert(int *out, git_repository *repo)
 {
 	git_config *cfg;
 	const char *val;
-	int check_cert;
+	int error = 0;
+
+	assert(out && repo);
 
-	assert(repo);
+	/* By default, we *DO* want to verify the certificate. */
+	*out = 1;
 
 	/* Go through the possible sources for SSL verification settings, from
 	 * most specific to least specific. */
 
 	/* GIT_SSL_NO_VERIFY environment variable */
-	if ((val = getenv("GIT_SSL_NO_VERIFY")) &&
-		!git_config_parse_bool(&check_cert, val))
-		return !check_cert;
+	if (val = getenv("GIT_SSL_NO_VERIFY"))
+		return git_config_parse_bool(out, val);
 
 	/* http.sslVerify config setting */
-	if (!git_repository_config__weakptr(&cfg, repo) &&
-		!git_config_get_bool(&check_cert, cfg, "http.sslVerify"))
-		return check_cert;
+	if ((error = git_repository_config__weakptr(&cfg, repo)) < 0)
+		return error;
 
-	/* By default, we *DO* want to verify the certificate. */
-	return 1;
+	if ((error = git_config_get_bool(out, cfg, "http.sslVerify")) == 0)
+		return 0;
+	else if (error != GIT_ENOTFOUND)
+		return error;
+
+	giterr_clear();
+	return 0;
 }
 
 static int create_internal(git_remote **out, git_repository *repo, const char *name, const char *url, const char *fetch)
@@ -120,9 +126,11 @@ static int create_internal(git_remote **out, git_repository *repo, const char *n
 	GITERR_CHECK_ALLOC(remote);
 
 	remote->repo = repo;
-	remote->check_cert = (unsigned)get_check_cert(repo);
 	remote->update_fetchhead = 1;
 
+	if (get_check_cert(&remote->check_cert, repo) < 0)
+		goto on_error;
+
 	if (git_vector_init(&remote->refs, 32, NULL) < 0)
 		goto on_error;
 
@@ -314,11 +322,13 @@ int git_remote_load(git_remote **out, git_repository *repo, const char *name)
 	GITERR_CHECK_ALLOC(remote);
 
 	memset(remote, 0x0, sizeof(git_remote));
-	remote->check_cert = (unsigned)get_check_cert(repo);
 	remote->update_fetchhead = 1;
 	remote->name = git__strdup(name);
 	GITERR_CHECK_ALLOC(remote->name);
 
+	if ((error = get_check_cert(&remote->check_cert, repo)) < 0)
+		goto cleanup;
+
 	if ((git_vector_init(&remote->refs, 32, NULL) < 0) ||
 	    (git_vector_init(&remote->refspecs, 2, NULL) < 0) ||
 	    (git_vector_init(&remote->active_refspecs, 2, NULL) < 0)) {
@@ -610,13 +620,14 @@ int git_remote_connect(git_remote *remote, git_direction direction)
 	git_transport *t;
 	const char *url;
 	int flags = GIT_TRANSPORTFLAGS_NONE;
+	int error;
 
 	assert(remote);
 
 	t = remote->transport;
 
 	url = git_remote__urlfordirection(remote, direction);
-	if (url == NULL ) {
+	if (url == NULL) {
 		giterr_set(GITERR_INVALID,
 			"Malformed remote '%s' - missing URL", remote->name);
 		return -1;
@@ -624,17 +635,17 @@ int git_remote_connect(git_remote *remote, git_direction direction)
 
 	/* A transport could have been supplied in advance with
 	 * git_remote_set_transport */
-	if (!t && git_transport_new(&t, remote, url) < 0)
-		return -1;
+	if (!t && (error = git_transport_new(&t, remote, url)) < 0)
+		return error;
 
 	if (t->set_callbacks &&
-		t->set_callbacks(t, remote->callbacks.progress, NULL, remote->callbacks.payload) < 0)
+		(error = t->set_callbacks(t, remote->callbacks.progress, NULL, remote->callbacks.payload)) < 0)
 		goto on_error;
 
 	if (!remote->check_cert)
 		flags |= GIT_TRANSPORTFLAGS_NO_CHECK_CERT;
 
-	if (t->connect(t, url, remote->callbacks.credentials, remote->callbacks.payload, direction, flags) < 0)
+	if ((error = t->connect(t, url, remote->callbacks.credentials, remote->callbacks.payload, direction, flags)) < 0)
 		goto on_error;
 
 	remote->transport = t;
@@ -647,7 +658,7 @@ on_error:
 	if (t == remote->transport)
 		remote->transport = NULL;
 
-	return -1;
+	return error;
 }
 
 int git_remote_ls(const git_remote_head ***out, size_t *size, git_remote *remote)
@@ -661,6 +672,7 @@ int git_remote__get_http_proxy(git_remote *remote, bool use_ssl, char **proxy_ur
 {
 	git_config *cfg;
 	const char *val;
+	int error;
 
 	assert(remote);
 
@@ -669,8 +681,8 @@ int git_remote__get_http_proxy(git_remote *remote, bool use_ssl, char **proxy_ur
 
 	*proxy_url = NULL;
 
-	if (git_repository_config__weakptr(&cfg, remote->repo) < 0)
-		return -1;
+	if ((error = git_repository_config__weakptr(&cfg, remote->repo)) < 0)
+		return error;
 
 	/* Go through the possible sources for proxy configuration, from most specific
 	 * to least specific. */
@@ -679,28 +691,33 @@ int git_remote__get_http_proxy(git_remote *remote, bool use_ssl, char **proxy_ur
 	if (remote->name && 0 != *(remote->name)) {
 		git_buf buf = GIT_BUF_INIT;
 
-		if (git_buf_printf(&buf, "remote.%s.proxy", remote->name) < 0)
-			return -1;
+		if ((error = git_buf_printf(&buf, "remote.%s.proxy", remote->name)) < 0)
+			return error;
 
-		if (!git_config_get_string(&val, cfg, git_buf_cstr(&buf)) &&
+		if ((error = git_config_get_string(&val, cfg, git_buf_cstr(&buf))) == 0 &&
 			val && ('\0' != *val)) {
 			git_buf_free(&buf);
 
 			*proxy_url = git__strdup(val);
 			GITERR_CHECK_ALLOC(*proxy_url);
 			return 0;
-		}
+		} else if (error != GIT_ENOTFOUND)
+			return error;
 
+		giterr_clear();
 		git_buf_free(&buf);
 	}
 
 	/* http.proxy config setting */
-	if (!git_config_get_string(&val, cfg, "http.proxy") &&
+	if ((error = git_config_get_string(&val, cfg, "http.proxy")) == 0 &&
 		val && ('\0' != *val)) {
 		*proxy_url = git__strdup(val);
 		GITERR_CHECK_ALLOC(*proxy_url);
 		return 0;
-	}
+	} else if (error != GIT_ENOTFOUND)
+		return error;
+
+	giterr_clear();
 
 	/* HTTP_PROXY / HTTPS_PROXY environment variables */
 	val = use_ssl ? getenv("HTTPS_PROXY") : getenv("HTTP_PROXY");
diff --git a/src/transports/cred.c b/src/transports/cred.c
index cc7fdab..05d2c8d 100644
--- a/src/transports/cred.c
+++ b/src/transports/cred.c
@@ -29,6 +29,10 @@ int git_cred_has_username(git_cred *cred)
 		ret = !!c->username;
 		break;
 	}
+	case GIT_CREDTYPE_DEFAULT: {
+		ret = 0;
+		break;
+	}
 	}
 
 	return ret;
@@ -115,6 +119,13 @@ static void ssh_custom_free(struct git_cred *cred)
 	git__free(c);
 }
 
+static void default_free(struct git_cred *cred)
+{
+	git_cred_default *c = (git_cred_default *)cred;
+
+	git__free(c);
+}
+
 int git_cred_ssh_key_new(
 	git_cred **cred,
 	const char *username,
@@ -191,3 +202,19 @@ int git_cred_ssh_custom_new(
 	*cred = &c->parent;
 	return 0;
 }
+
+int git_cred_default_new(git_cred **cred)
+{
+	git_cred_default *c;
+
+	assert(cred);
+
+	c = git__calloc(1, sizeof(git_cred_default));
+	GITERR_CHECK_ALLOC(c);
+
+	c->credtype = GIT_CREDTYPE_DEFAULT;
+	c->free = default_free;
+
+	*cred = c;
+	return 0;
+}
diff --git a/src/transports/smart_protocol.c b/src/transports/smart_protocol.c
index 7288a48..3bf1f93 100644
--- a/src/transports/smart_protocol.c
+++ b/src/transports/smart_protocol.c
@@ -49,7 +49,7 @@ int git_smart__store_refs(transport_smart *t, int flushes)
 
 		if (error == GIT_EBUFS) {
 			if ((recvd = gitno_recv(buf)) < 0)
-				return -1;
+				return recvd;
 
 			if (recvd == 0 && !flush) {
 				giterr_set(GITERR_NET, "Early EOF");
@@ -164,10 +164,10 @@ static int recv_pkt(git_pkt **out, gitno_buffer *buf)
 			break; /* return the pkt */
 
 		if (error < 0 && error != GIT_EBUFS)
-			return -1;
+			return error;
 
 		if ((ret = gitno_recv(buf)) < 0)
-			return -1;
+			return ret;
 	} while (error);
 
 	gitno_consume(buf, line_end);
@@ -184,10 +184,11 @@ static int store_common(transport_smart *t)
 {
 	git_pkt *pkt = NULL;
 	gitno_buffer *buf = &t->buffer;
+	int error;
 
 	do {
-		if (recv_pkt(&pkt, buf) < 0)
-			return -1;
+		if ((error = recv_pkt(&pkt, buf)) < 0)
+			return error;
 
 		if (pkt->type == GIT_PKT_ACK) {
 			if (git_vector_insert(&t->common, pkt) < 0)
@@ -227,6 +228,7 @@ static int fetch_setup_walk(git_revwalk **out, git_repository *repo)
 
 		if (git_reference_type(ref) == GIT_REF_SYMBOLIC)
 			continue;
+
 		if (git_revwalk_push(walk, git_reference_target(ref)) < 0)
 			goto on_error;
 
@@ -436,10 +438,10 @@ static int no_sideband(transport_smart *t, struct git_odb_writepack *writepack, 
 		gitno_consume_n(buf, buf->offset);
 
 		if ((recvd = gitno_recv(buf)) < 0)
-			return -1;
+			return recvd;
 	} while(recvd > 0);
 
-	if (writepack->commit(writepack, stats))
+	if (writepack->commit(writepack, stats) < 0)
 		return -1;
 
 	return 0;
@@ -697,7 +699,7 @@ static int parse_report(gitno_buffer *buf, git_push *push)
 
 		if (error == GIT_EBUFS) {
 			if ((recvd = gitno_recv(buf)) < 0)
-				return -1;
+				return recvd;
 
 			if (recvd == 0) {
 				giterr_set(GITERR_NET, "Early EOF");
diff --git a/src/transports/winhttp.c b/src/transports/winhttp.c
index a25fa30..673cd0f 100644
--- a/src/transports/winhttp.c
+++ b/src/transports/winhttp.c
@@ -52,6 +52,7 @@ static const int no_check_cert_flags = SECURITY_FLAG_IGNORE_CERT_CN_INVALID |
 
 typedef enum {
 	GIT_WINHTTP_AUTH_BASIC = 1,
+	GIT_WINHTTP_AUTH_NEGOTIATE = 2,
 } winhttp_authmechanism_t;
 
 typedef struct {
@@ -138,6 +139,22 @@ on_error:
 	return error;
 }
 
+static int apply_default_credentials(HINTERNET request)
+{
+	/* If we are explicitly asked to deliver default credentials, turn set
+	 * the security level to low which will guarantee they are delivered.
+	 * The default is "medium" which applies to the intranet and sounds
+	 * like it would correspond to Internet Explorer security zones, but
+	 * in fact does not.
+	 */
+	DWORD data = WINHTTP_AUTOLOGON_SECURITY_LEVEL_LOW;
+
+	if (!WinHttpSetOption(request, WINHTTP_OPTION_AUTOLOGON_POLICY, &data, sizeof(DWORD)))
+		return -1;
+
+	return 0;
+}
+
 static int winhttp_stream_connect(winhttp_stream *s)
 {
 	winhttp_subtransport *t = OWNING_SUBTRANSPORT(s);
@@ -317,6 +334,11 @@ static int winhttp_stream_connect(winhttp_stream *s)
 		t->auth_mechanism == GIT_WINHTTP_AUTH_BASIC &&
 		apply_basic_credential(s->request, t->cred) < 0)
 		goto on_error;
+	else if (t->cred &&
+		t->cred->credtype == GIT_CREDTYPE_DEFAULT &&
+		t->auth_mechanism == GIT_WINHTTP_AUTH_NEGOTIATE &&
+		apply_default_credentials(s->request) < 0)
+		goto on_error;
 
 	/* If no other credentials have been applied and the URL has username and
 	 * password, use those */
@@ -361,6 +383,12 @@ static int parse_unauthorized_response(
 		*auth_mechanism = GIT_WINHTTP_AUTH_BASIC;
 	}
 
+	if ((WINHTTP_AUTH_SCHEME_NTLM & supported) ||
+		(WINHTTP_AUTH_SCHEME_NEGOTIATE & supported)) {
+		*allowed_types |= GIT_CREDTYPE_DEFAULT;
+		*auth_mechanism = GIT_WINHTTP_AUTH_NEGOTIATE;
+	}
+
 	return 0;
 }
 
@@ -640,8 +668,8 @@ replay:
 				(!t->cred || 0 == (t->cred->credtype & allowed_types))) {
 
 				if (t->owner->cred_acquire_cb(&t->cred, t->owner->url, t->connection_data.user, allowed_types, 
-								t->owner->cred_acquire_payload) < 0)
-					return -1;
+					t->owner->cred_acquire_payload) < 0)
+					return GIT_EUSER;
 
 				assert(t->cred);
 
diff --git a/tests/online/clone.c b/tests/online/clone.c
index aa3d6b2..d036a5a 100644
--- a/tests/online/clone.c
+++ b/tests/online/clone.c
@@ -183,6 +183,39 @@ void test_online_clone__custom_remote_callbacks(void)
 	cl_assert(callcount > 0);
 }
 
+static int cred_failure_cb(
+	git_cred **cred,
+	const char *url,
+	const char *username_from_url,
+	unsigned int allowed_types,
+	void *data)
+{
+	return -1;
+}
+
+void test_online_clone__cred_callback_failure_is_euser(void)
+{
+	const char *remote_url = cl_getenv("GITTEST_REMOTE_URL");
+	const char *remote_user = cl_getenv("GITTEST_REMOTE_USER");
+	const char *remote_default = cl_getenv("GITTEST_REMOTE_DEFAULT");
+	int error;
+
+	if (!remote_url) {
+		printf("GITTEST_REMOTE_URL unset; skipping clone test\n");
+		return;
+	}
+
+	if (!remote_user && !remote_default) {
+		printf("GITTEST_REMOTE_USER and GITTEST_REMOTE_DEFAULT unset; skipping clone test\n");
+		return;
+	}
+
+	g_options.remote_callbacks.credentials = cred_failure_cb;
+
+	cl_git_fail(error = git_clone(&g_repo, remote_url, "./foo", &g_options));
+	cl_assert_equal_i(error, GIT_EUSER);
+}
+
 void test_online_clone__credentials(void)
 {
 	/* Remote URL environment variable must be set.  User and password are optional.  */
diff --git a/tests/online/push.c b/tests/online/push.c
index aeb1ab4..be505c3 100644
--- a/tests/online/push.c
+++ b/tests/online/push.c
@@ -9,14 +9,17 @@
 
 static git_repository *_repo;
 
+static char *_remote_url;
+
 static char *_remote_ssh_key;
 static char *_remote_ssh_pubkey;
 static char *_remote_ssh_passphrase;
 
-static char *_remote_url;
 static char *_remote_user;
 static char *_remote_pass;
 
+static char *_remote_default;
+
 static int cred_acquire_cb(git_cred **,	const char *, const char *, unsigned int, void *);
 
 static git_remote *_remote;
@@ -47,11 +50,21 @@ static int cred_acquire_cb(
 	GIT_UNUSED(user_from_url);
 	GIT_UNUSED(payload);
 
+	if (GIT_CREDTYPE_DEFAULT & allowed_types) {
+		if (!_remote_default) {
+			printf("GITTEST_REMOTE_DEFAULT must be set to use NTLM/Negotiate credentials\n");
+			return -1;
+		}
+
+		return git_cred_default_new(cred);
+	}
+
 	if (GIT_CREDTYPE_SSH_KEY & allowed_types) {
 		if (!_remote_user || !_remote_ssh_pubkey || !_remote_ssh_key || !_remote_ssh_passphrase) {
 			printf("GITTEST_REMOTE_USER, GITTEST_REMOTE_SSH_PUBKEY, GITTEST_REMOTE_SSH_KEY and GITTEST_REMOTE_SSH_PASSPHRASE must be set\n");
 			return -1;
 		}
+
 		return git_cred_ssh_key_new(cred, _remote_user, _remote_ssh_pubkey, _remote_ssh_key, _remote_ssh_passphrase);
 	}
 
@@ -298,6 +311,7 @@ void test_online_push__initialize(void)
 	_remote_ssh_key = cl_getenv("GITTEST_REMOTE_SSH_KEY");
 	_remote_ssh_pubkey = cl_getenv("GITTEST_REMOTE_SSH_PUBKEY");
 	_remote_ssh_passphrase = cl_getenv("GITTEST_REMOTE_SSH_PASSPHRASE");
+	_remote_default = cl_getenv("GITTEST_REMOTE_DEFAULT");
 	_remote = NULL;
 
 	if (_remote_url) {