Add json-ipc message plumbing

Signed-off-by: Jim Ramsay <i.am@jimramsay.com>

include/json-ipc.h

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2022 Jim Ramsay
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#pragma once
+
+#include <jansson.h>
+
+struct jsonipc_request {
+	const char* method;
+	json_t* params;
+	json_t* id;
+
+	json_t* json;
+};
+
+#define IPC_CODE_SUCCESS 0
+
+struct jsonipc_error {
+	int code;
+	json_t* data;
+};
+
+#define JSONIPC_ERR_INIT {0,NULL}
+
+struct jsonipc_response {
+	int code;
+	json_t* data;
+	json_t* id;
+
+	json_t* json;
+};
+
+void jsonipc_error_set_new(struct jsonipc_error*, int code, json_t* data);
+void jsonipc_error_printf(struct jsonipc_error*, int code, const char* fmt, ...);
+void jsonipc_error_set_from_errno(struct jsonipc_error*, const char* context);
+void jsonipc_error_cleanup(struct jsonipc_error*);
+
+struct jsonipc_request* jsonipc_request_parse_new(json_t* root,
+		struct jsonipc_error* err);
+struct jsonipc_request* jsonipc_request_new(const char* method, json_t* params);
+json_t* jsonipc_request_pack(struct jsonipc_request*, json_error_t* err);
+void jsonipc_request_destroy(struct jsonipc_request*);
+
+struct jsonipc_response* jsonipc_response_parse_new(json_t* root,
+		struct jsonipc_error* err);
+struct jsonipc_response* jsonipc_response_new(int code, json_t* data,
+		json_t* id);
+struct jsonipc_response* jsonipc_error_response_new(struct jsonipc_error* err,
+		json_t* id);
+void jsonipc_response_destroy(struct jsonipc_response*);
+json_t* jsonipc_response_pack(struct jsonipc_response*, json_error_t* err);
+
+json_t* jprintf(const char* fmt, ...);
+json_t* jvprintf(const char* fmt, va_list ap);

meson.build

@@ -47,6 +47,7 @@ gbm = dependency('gbm', required: get_option('screencopy-dmabuf'))
 drm = dependency('libdrm')
 xkbcommon = dependency('xkbcommon', version: '>=1.0.0')
 wayland_client = dependency('wayland-client')
+jansson = dependency('jansson')
 
 neatvnc_version = '>=0.5.0'
 
@@ -89,6 +90,7 @@ sources = [
 	'src/buffer.c',
 	'src/pixels.c',
 	'src/transform-util.c',
+	'src/json-ipc.c',
 ]
 
 dependencies = [
@@ -102,6 +104,7 @@ dependencies = [
 	neatvnc,
 	xkbcommon,
 	client_protos,
+	jansson,
 ]
 
 config = configuration_data()

src/json-ipc.c

@@ -0,0 +1,196 @@
+/*
+ * Copyright (c) 2022 Jim Ramsay
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <string.h>
+#include <stdbool.h>
+#include <errno.h>
+#include "json-ipc.h"
+
+static const char* jsonipc_id_key = "id";
+static const char* jsonipc_method_key = "method";
+static const char* jsonipc_params_key = "params";
+static const char* jsonipc_code_key = "code";
+static const char* jsonipc_data_key = "data";
+
+void jsonipc_error_set_new(struct jsonipc_error* err, int code, json_t* data)
+{
+	if (!err)
+		return;
+	err->code = code;
+	err->data = data;
+}
+
+void jsonipc_error_printf(struct jsonipc_error* err, int code, const char* fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	jsonipc_error_set_new(err, code, json_pack("{s:o}", "error",
+				jvprintf(fmt, ap)));
+	va_end(ap);
+}
+
+void jsonipc_error_set_from_errno(struct jsonipc_error* err,
+		const char* context)
+{
+	jsonipc_error_printf(err, errno, "%s: %m", context);
+}
+
+void jsonipc_error_cleanup(struct jsonipc_error* err)
+{
+	if (!err)
+		return;
+	json_decref(err->data);
+}
+
+inline static bool is_valid_id(json_t* id)
+{
+	return id == NULL ||
+		json_is_string(id) || json_is_number(id);
+}
+
+struct jsonipc_request* jsonipc_request_parse_new(json_t* root,
+		struct jsonipc_error* err)
+{
+	struct jsonipc_request* ipc = calloc(1, sizeof(*ipc));
+	ipc->json = root;
+	json_incref(ipc->json);
+	json_error_t unpack_error;
+	if (json_unpack_ex(root, &unpack_error, 0, "{s:s, s?O, s?O}",
+				jsonipc_method_key, &ipc->method,
+				jsonipc_params_key, &ipc->params,
+				jsonipc_id_key, &ipc->id) == -1) {
+		jsonipc_error_printf(err, EINVAL, unpack_error.text);
+		goto failure;
+	}
+	if (!is_valid_id(ipc->id)) {
+		char* id = json_dumps(ipc->id, JSON_EMBED | JSON_ENCODE_ANY);
+		jsonipc_error_printf(err, EINVAL,
+				"Invalid ID \"%s\"", id);
+		free(id);
+		goto failure;
+	}
+	return ipc;
+
+failure:
+	jsonipc_request_destroy(ipc);
+	return NULL;
+}
+
+static int request_id = 1;
+struct jsonipc_request* jsonipc_request_new(const char* method, json_t* params)
+{
+	struct jsonipc_request* ipc = calloc(1, sizeof(*ipc));
+	ipc->method = method;
+	ipc->params = params;
+	json_incref(ipc->params);
+	ipc->id = json_integer(request_id++);
+	return ipc;
+}
+
+json_t* jsonipc_request_pack(struct jsonipc_request* self, json_error_t* err)
+{
+	return json_pack_ex(err, 0, "{s:s, s:O*, s:O*}",
+			jsonipc_method_key, self->method,
+			jsonipc_params_key, self->params,
+			jsonipc_id_key, self->id);
+}
+
+void jsonipc_request_destroy(struct jsonipc_request* self)
+{
+	json_decref(self->params);
+	json_decref(self->id);
+	json_decref(self->json);
+	free(self);
+}
+
+struct jsonipc_response* jsonipc_response_parse_new(json_t* root,
+		struct jsonipc_error* err)
+{
+	struct jsonipc_response* ipc = calloc(1, sizeof(*ipc));
+	ipc->json = root;
+	json_incref(ipc->json);
+	json_error_t unpack_error;
+	if (json_unpack_ex(root, &unpack_error, 0, "{s:i, s?O, s?O}",
+				jsonipc_code_key, &ipc->code,
+				jsonipc_data_key, &ipc->data,
+				jsonipc_id_key, &ipc->id) == -1) {
+		jsonipc_error_printf(err, EINVAL, unpack_error.text);
+		goto failure;
+	}
+	if (!is_valid_id(ipc->id)) {
+		char* id = json_dumps(ipc->id, JSON_EMBED | JSON_ENCODE_ANY);
+		jsonipc_error_printf(err, EINVAL,
+				"Invalid ID \"%s\"", id);
+		free(id);
+		goto failure;
+	}
+	return ipc;
+
+failure:
+	jsonipc_response_destroy(ipc);
+	return NULL;
+}
+
+struct jsonipc_response* jsonipc_response_new(int code,
+		json_t* data, json_t* id)
+{
+	struct jsonipc_response* rsp = calloc(1, sizeof(*rsp));
+	rsp->code = code;
+	json_incref(id);
+	rsp->id = id;
+	json_incref(data);
+	rsp->data = data;
+	return rsp;
+}
+
+struct jsonipc_response* jsonipc_error_response_new(
+		struct jsonipc_error* err,
+		json_t* id)
+{
+	return jsonipc_response_new(err->code, err->data, id);
+}
+
+void jsonipc_response_destroy(struct jsonipc_response* self)
+{
+	json_decref(self->data);
+	json_decref(self->json);
+	json_decref(self->id);
+	free(self);
+}
+
+json_t* jsonipc_response_pack(struct jsonipc_response* self, json_error_t* err)
+{
+	return json_pack_ex(err, 0, "{s:i, s:O*, s:O*}",
+			jsonipc_code_key, self->code,
+			jsonipc_id_key, self->id,
+			jsonipc_data_key, self->data);
+}
+
+json_t* jprintf(const char* fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	json_t* result = jvprintf(fmt, args);
+	va_end(args);
+	return result;
+}
+
+json_t* jvprintf(const char* fmt, va_list ap)
+{
+	char buffer[128];
+	int len = vsnprintf(buffer, sizeof(buffer), fmt, ap);
+	return json_stringn(buffer, len);
+}