serialise and deserialise very basic json data, and send it between server and client

README.gmi

@@ -5,8 +5,12 @@ Note: I'm not galaxy-brained enough to do the full idea at the moment, so this i
 
 ## Build from Source
 ### Dependencies
+#### All
 * CMake
+
+#### Common Library
 * Lua 5.4
+* Jansson
 
 ### Building
 ```

client/src/main.c

@@ -1,10 +1,10 @@
 // main.c
 
 #include <stdio.h>
-#include <string.h>
 #include <unistd.h>
 #include <sys/socket.h>
 
+#include "world.h"
 #include "error.h"
 #include "sock.h"
 
@@ -15,15 +15,25 @@ int main(void) {
     err = sock_init(&sock);
     if (err) goto handle_error;
 
-    char ibuf[1028] = { 0 };
-    char obuf[1028] = { 0 };
-    strcpy(obuf, "Hello, world!\n");
+    char ibuf[1024] = { 0 };
+    char obuf[1024] = { 0 };
 
-    // Just echoing everything back for now
-    write(sock, obuf, 1028);
-    int rc = read(sock, ibuf, 1028);
+    // TODO: I skipped out on most error handling here
+    read(sock, ibuf, 1024);
 
-    if (rc > 0) printf("%s", ibuf);
+    struct json_error_t json_err;
+    struct json_t *json = json_loads(ibuf, 0, &json_err);
+
+    struct world_t world = { 0 };
+    world_deserialise(&world, json);
+
+    printf("CLIENT: (%zu %zu)\n", world.height, world.width);
+
+    struct json_t *new_json;
+    world_serialise(&world, &new_json);
+
+    json_dumpb(new_json, obuf, 1024, 0);
+    write(sock, obuf, 1024);
 
     close(sock);
     return ERR_OK;

client/src/sock.c

@@ -16,8 +16,7 @@ enum error_t sock_init(int *sockptr) {
 
     struct sockaddr_un sa = { 0 };
     sa.sun_family = AF_UNIX;
-    strcpy(sa.sun_path, "/tmp/swd.sock");
-        // Socket path should be a shared setting between server and client
+    strcpy(sa.sun_path, SOCK_PATH);
 
     if (connect(sock, (struct sockaddr *)&sa, sizeof(sa))) goto sock_error;
 

client/src/sock.h

@@ -3,6 +3,8 @@
 
 #include "error.h"
 
+#define SOCK_PATH "/tmp/swd.sock"
+
 enum error_t sock_init(int *);
 
 #endif

common/CMakeLists.txt

@@ -10,7 +10,9 @@ add_library(${PROJECT_NAME} SHARED ${SOURCES})
 target_include_directories(${PROJECT_NAME} PUBLIC ${CMAKE_SOURCE_DIR}/common/include)
 
 find_package(PkgConfig REQUIRED)
-pkg_check_modules(LUA REQUIRED lua)
 
-target_link_libraries(${PROJECT_NAME} ${LUA_LIBRARIES})
-target_include_directories(${PROJECT_NAME} PRIVATE ${LUA_INCLUDE_DIRS})
+pkg_check_modules(LUA REQUIRED lua)
+pkg_check_modules(JANSSON REQUIRED jansson)
+
+target_link_libraries(${PROJECT_NAME} ${LUA_LIBRARIES} ${JANSSON_LIBRARIES})
+target_include_directories(${PROJECT_NAME} PRIVATE ${LUA_INCLUDE_DIRS} ${JANSSON_INCLUDE_DIRS})

common/include/error.h

@@ -9,6 +9,8 @@ enum error_t {
     ERR_FORK,
     ERR_SETSID,
     ERR_SOCKET,
+    ERR_JSON_SERIALISE,
+    ERR_JSON_DESERIALISE,
     __ERR_COUNT,
 };
 

common/include/world.h

@@ -3,6 +3,8 @@
 
 #include <stdlib.h>
 
+#include <jansson.h>
+
 #include "error.h"
 #include "entity/registry.h"
 #include "entity/entity.h"
@@ -20,6 +22,20 @@ struct world_t {
 enum error_t world_init(struct world_t *, size_t, size_t);
 void world_free(struct world_t *);
 
+// json_t doesn't store the json data itself; the value of the pointer is
+// apparently needed for jansson to use the data, so I need a double pointer
+//
+// TODO
+// Right now, to serialise and deserialise again you have to call:
+// 1. world_serialise()   | world_t -> json_t
+// 2. json_dumpX()        |  json_t -> char *
+// 3. json_loadX()        |  char * -> json_t
+// 4. world_deserialise() |  json_t -> world_t
+//
+// Perhaps these two functions should go directly between world_t and char *
+enum error_t world_serialise(struct world_t *, struct json_t **);
+enum error_t world_deserialise(struct world_t *, struct json_t *);
+
 enum error_t world_register_entity(struct world_t *, char const *, char);
 enum error_t world_place_entity(struct world_t *, size_t, size_t, size_t);
 

common/src/error.c

@@ -10,6 +10,8 @@ char const *const ERROR_STRS[] = {
     "FORK",
     "SETSID",
     "SOCKET",
+    "JSON SERIALISATION",
+    "JSON DESERIALISATION",
 };
 
 

common/src/world.c

@@ -34,14 +34,50 @@ enum error_t world_init(struct world_t *self, size_t height, size_t width) {
 
 
 void world_free(struct world_t *self) {
+    assert(self != NULL);
+
     entity_registry_free(&self->registered_entities);
 }
 
 
+enum error_t world_serialise(struct world_t *self, struct json_t **json) {
+    assert(self != NULL);
+    // TODO: (de)serialise the following:
+    // struct entity_t entities[MAX_ENTITIES];
+    // struct entity_registry_t registered_entities;
+
+    struct json_t *maybe_json = json_pack("{s:I,s:I}",
+        "height", self->height,
+        "width", self->width
+    );
+    if (maybe_json == NULL) return ERR_JSON_SERIALISE;
+
+    *json = maybe_json;
+    return ERR_OK;
+}
+
+
+enum error_t world_deserialise(struct world_t *self, struct json_t *json) {
+    assert(self != NULL);
+    assert(json != NULL);
+
+    int err = json_unpack(json, "{s:I,s:I}",
+        "height", &self->height,
+        "width", &self->width
+    );
+    if (err < 0) return ERR_JSON_DESERIALISE;
+
+    return ERR_OK;
+}
+
+
 enum error_t world_register_entity(
     struct world_t *self,
     char const *name, char tile
 ) {
+    assert(self != NULL);
+    assert(name != NULL);
+
     enum error_t err;
     struct entity_registry_t *registry = &self->registered_entities;
 
@@ -57,6 +93,8 @@ enum error_t world_register_entity(
 
 
 static size_t world_find_empty_entity(struct world_t const *self) {
+    assert(self != NULL);
+
     for (size_t i = 0; i < MAX_ENTITIES; i++)
         if (self->entities[i].id == 0) return i;
 

server/src/data.h

@@ -2,8 +2,10 @@
 #define DAEMON_DATA_H
 
 #include "world.h"
+#include "opts.h"
 
 struct data_t {
+    struct options_t options;
     struct world_t world;
 
     int socket;

server/src/main.c

@@ -22,11 +22,34 @@ static void handle_signal(int signal_no) {
 }
 
 
-enum error_t game_loop(struct data_t *data) {
-    uint8_t buffer[1024] = { 0 };
+#define LOGMSG(options, fmt, ...) \
+    ((options)->daemonise ? \
+        syslog(LOG_NOTICE, (fmt), __VA_ARGS__) : \
+        (void)printf((fmt), __VA_ARGS__))
 
-    read(data->socket_accept, buffer, 1024);
-    write(data->socket_accept, buffer, 1024);
+
+enum error_t game_loop(struct data_t *data) {
+    enum error_t err = ERR_OK;
+    char obuf[1024] = { 0 };
+    char ibuf[1024] = { 0 };
+
+    // TODO: I skipped out on most error handling here
+    struct json_t *json;
+    err = world_serialise(&data->world, &json);
+    if (err != ERR_OK) return err;
+
+    json_dumpb(json, obuf, 1024, 0);
+    write(data->socket_accept, obuf, 1024);
+
+    read(data->socket_accept, ibuf, 1024);
+    json = json_loads(ibuf, 0, NULL);
+
+    struct world_t returned_world;
+    world_deserialise(&returned_world, json);
+    LOGMSG(&data->options, "SERVER: (%zu %zu) -> (%zu %zu)\n",
+        data->world.height, data->world.width,
+        returned_world.height, returned_world.width
+    );
 
     return ERR_OK;
 }
@@ -42,13 +65,12 @@ int main(int argc, char **argv) {
     signal(SIGTERM, handle_signal);
 
     // Handle commandline options
-    struct options_t options = { 0 };
-    opts_default(&options);
+    opts_default(&data.options);
 
-    err = opts_parse(&options, argc, argv);
+    err = opts_parse(&data.options, argc, argv);
     if (err) goto handle_error_pre_opts;
 
-    err = opts_init(&options);
+    err = opts_init(&data.options);
     if (err) goto handle_error;
 
     // World initialisation
@@ -61,42 +83,21 @@ int main(int argc, char **argv) {
     err = world_place_entity(&data.world, 1, 3, 7);
     if (err) goto handle_error_world;
 
-    // Temporary code because I just realised I need to properly serialise
-    // data because pointers don't work cross-socket
-    // TODO: Serialise to JSON
-    const char *fmt = "%zu (%s) (%zu, %zu) '%c'\n";
-    struct entity_t const *const entity = &data.world.entities[0];
-    struct entity_registrant_t const *const registrant =
-        &data.world.registered_entities.entities[entity->id];
-
-    if (options.daemonise)
-        syslog(LOG_NOTICE, fmt,
-            entity->id, registrant->name,
-            entity->x, entity->y,
-            registrant->tile
-        );
-    else
-        printf(fmt,
-            entity->id, registrant->name,
-            entity->x, entity->y,
-            registrant->tile
-        );
-
     // Socket handling and run gameloop
     err = sock_loop(&data, game_loop);
     if (err) goto handle_error;
 
     // Deinitialisation
     world_free(&data.world);
-    opts_free(&options);
+    opts_free(&data.options);
     return ERR_OK;
 
 handle_error_world:
     world_free(&data.world);
 
 handle_error:
-    if (options.daemonise) syslog(LOG_ERR, "%s", ERROR_STRS[err]);
-    opts_free(&options);
+    if (data.options.daemonise) syslog(LOG_ERR, "%s", ERROR_STRS[err]);
+    opts_free(&data.options);
 
 handle_error_pre_opts:
     printf("ERROR: %s\n", ERROR_STRS[err]);