add command module to handle request-response communications

1 files changed, 157 insertions, 0 deletions

diff --git a/src/command.c b/src/command.c
new file mode 100644
index 0000000..b1204a9
--- /dev/null
+++ b/src/command.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2023 Egor Tensin <Egor.Tensin@gmail.com>
+ * This file is part of the "cimple" project.
+ * For details, see https://github.com/egor-tensin/cimple.
+ * Distributed under the MIT License.
+ */
+
+#include "command.h"
+#include "log.h"
+#include "msg.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+struct command_dispatcher {
+	struct command_def *defs;
+	size_t numof_defs;
+	void *ctx;
+};
+
+static int copy_def(struct command_def *dest, const struct command_def *src)
+{
+	dest->name = strdup(src->name);
+	if (!dest->name) {
+		log_errno("strdup");
+		return -1;
+	}
+	dest->processor = src->processor;
+	return 0;
+}
+
+static void free_def(struct command_def *def)
+{
+	free(def->name);
+}
+
+static int copy_defs(struct command_def *dest, const struct command_def *src, size_t numof_defs)
+{
+	size_t numof_copied, i;
+	int ret = 0;
+
+	for (numof_copied = 0; numof_copied < numof_defs; ++numof_copied) {
+		ret = copy_def(&dest[numof_copied], &src[numof_copied]);
+		if (ret < 0)
+			goto free;
+	}
+
+	return 0;
+
+free:
+	for (i = 0; i < numof_copied; ++i)
+		free_def(&dest[numof_copied]);
+
+	return -1;
+}
+
+static void free_defs(struct command_def *defs, size_t numof_defs)
+{
+	size_t i;
+
+	for (i = 0; i < numof_defs; ++i)
+		free_def(&defs[i]);
+}
+
+int command_dispatcher_create(struct command_dispatcher **_dispatcher, struct command_def *defs,
+                              size_t numof_defs, void *ctx)
+{
+	struct command_dispatcher *dispatcher;
+	int ret = 0;
+
+	*_dispatcher = malloc(sizeof(struct command_dispatcher));
+	if (!*_dispatcher) {
+		log_errno("malloc");
+		return -1;
+	}
+	dispatcher = *_dispatcher;
+
+	dispatcher->defs = malloc(sizeof(struct command_def) * numof_defs);
+	if (!dispatcher->defs) {
+		log_errno("malloc");
+		goto free;
+	}
+	dispatcher->numof_defs = numof_defs;
+
+	ret = copy_defs(dispatcher->defs, defs, numof_defs);
+	if (ret < 0)
+		goto free_defs;
+
+	dispatcher->ctx = ctx;
+	return 0;
+
+free_defs:
+	free(dispatcher->defs);
+
+free:
+	free(dispatcher);
+
+	return -1;
+}
+
+void command_dispatcher_destroy(struct command_dispatcher *dispatcher)
+{
+	free_defs(dispatcher->defs, dispatcher->numof_defs);
+	free(dispatcher->defs);
+	free(dispatcher);
+}
+
+int command_dispatcher_msg_handler(const struct command_dispatcher *dispatcher, int conn_fd,
+                                   const struct msg *request)
+{
+	struct msg *response = NULL;
+	int ret = 0;
+
+	size_t numof_words = msg_get_length(request);
+	if (numof_words == 0)
+		goto unknown;
+
+	const char **words = msg_get_words(request);
+
+	for (size_t i = 0; i < dispatcher->numof_defs; ++i) {
+		struct command_def *def = &dispatcher->defs[i];
+
+		if (strcmp(def->name, words[0]))
+			continue;
+
+		ret = def->processor(conn_fd, request, dispatcher->ctx, &response);
+		goto exit;
+	}
+
+unknown:
+	log_err("Received an unknown command\n");
+	ret = -1;
+	msg_dump(request);
+	goto exit;
+
+exit:
+	if (ret < 0 && !response)
+		msg_error(&response);
+	if (response)
+		return msg_send(conn_fd, response);
+	return ret;
+}
+
+int command_dispatcher_conn_handler(int conn_fd, void *_dispatcher)
+{
+	struct command_dispatcher *dispatcher = (struct command_dispatcher *)_dispatcher;
+	struct msg *request;
+	int ret = 0;
+
+	ret = msg_recv(conn_fd, &request);
+	if (ret < 0)
+		return ret;
+
+	ret = command_dispatcher_msg_handler(dispatcher, conn_fd, request);
+	msg_free(request);
+	return ret;
+}