protocol: add C header work in progress and test client

The test client simply (optionally) requests a list of
hashes of an existing file.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

tests/proto-client.c

@@ -0,0 +1,77 @@
+/* Compile with:
+ *     $ make
+ *     $ gcc -o c-test-client tests/proto-client.c \
+ *         -L target/debug/deps -Wl,-rpath -Wl,target/debug/deps -lproxmox_protocol
+ *
+ * Run like:
+ *     $ ./c-test-client 'host/backup1/2019-03-06T10:06:52+01:00/foo.catar.fidx'
+ */
+
+#include <stdio.h>
+
+#include "../proxmox-protocol/proxmox-protocol.h"
+
+static bool useClient(ProxmoxBackup *client, int argc, char **argv);
+
+int
+main(int argc, char **argv)
+{
+	(void)argc;
+	(void)argv;
+
+	ProxmoxConnector *connector = proxmox_connector_new("root@pam", "127.0.0.1:8007", "local");
+	if (!connector) {
+		fprintf(stderr, "failed to create connector: %m\n");
+		return 1;
+	}
+
+	if (proxmox_connector_set_password(connector, "12341234") != 0) {
+		fprintf(stderr, "failed to set password: %m\n");
+		return 1;
+	}
+
+	proxmox_connector_set_certificate_validation(connector, false);
+
+	ProxmoxBackup *client = proxmox_connector_connect(connector);
+	if (!client) {
+		fprintf(stderr, "failed to connect\n");
+		return 1;
+	}
+
+	if (!useClient(client, argc, argv)) {
+		const char *msg = proxmox_backup_get_error(client);
+		if (msg) {
+			fprintf(stderr, "proxmox client error: %s\n", msg);
+		} else {
+			fprintf(stderr, "unknown proxmox client error\n", msg);
+		}
+	}
+
+	proxmox_backup_done(client);
+
+	return 0;
+}
+
+static bool
+useClient(ProxmoxBackup *client, int argc, char **argv)
+{
+	if (argc <= 1)
+		return true;
+
+	printf("requesting hashes for '%s'\n", argv[1]);
+	int rc = proxmox_backup_query_hashes(client, argv[1]);
+	if (rc < 0)
+		return false;
+
+	for (;;) {
+		printf("Wait iteration...\n");
+		int rc = proxmox_backup_wait_for_hashes(client);
+		if (rc < 0)
+			return false;
+		if (rc)
+			break;
+	}
+
+	printf("got hashes\n");
+	return true;
+}