feat(server): implemented listen and accept for tcp servers

include/cosms-core/networking/server.h

@@ -11,8 +11,12 @@
 
 #if defined(__linux__)
 #include <arpa/inet.h>
+
+#define COSMS_CORE_SERVER_INVALID_SOCKET -1
 #elif defined(_WIN32)
 #include <winsock2.h>
+
+#define COSMS_CORE_SERVER_INVALID_SOCKET (SOCKET)(0)
 #endif
 
 typedef enum {
@@ -23,7 +27,9 @@ typedef enum {
     COSMS_CORE_SERVER_UNKNOWN_ERROR = -3,
     COSMS_CORE_SERVER_TYPE_NOT_SUPPORTED = -4,
     COSMS_CORE_SERVER_FAILED_TO_RECEIVE = -5,
-    COSMS_CORE_SERVER_FAILED_TO_SEND = -6
+    COSMS_CORE_SERVER_FAILED_TO_SEND = -6,
+    COSMS_CORE_SERVER_FAILED_TO_ACCEPT = -7,
+    COSMS_CORE_SERVER_COULD_NOT_SET_MODE = -8
 } CosmsCoreServerError;
 
 struct cosms_core_server {
@@ -66,10 +72,41 @@ CosmsCoreServerError cosms_core_server_create(struct cosms_core_server *new_serv
  */
 CosmsCoreServerError cosms_core_server_destroy(struct cosms_core_server *current_server);
 
+/**
+ * @brief Sets server in listening state so it can listen for incomming connections (tcp only).
+ *
+ * @param current_server Pointer to an active server struct (must not be NULL)
+ * @param backlog How many clients will be put in the backlog before connections are declined
+ * @return COSMS_CORE_SERVER_OK on success, or negative error code
+ */
+inline CosmsCoreServerError cosms_core_server_listen(struct cosms_core_server *current_server, unsigned int backlog) {
+    int result = listen(current_server->listening_socket, backlog);
+    if (result == -1) {
+        return COSMS_CORE_SERVER_COULD_NOT_SET_MODE;
+    }
+
+    return COSMS_CORE_SERVER_OK;
+}
+/**
+ * @brief Accepts incomming connection (tcp only)
+ *
+ * @param current_server Pointer to an active server struct (must not be NULL)
+ * @param client Pointer to client struct to store the connected client in
+ * @return COSMS_CORE_SERVER_OK on success, or negative error code
+ */
+inline CosmsCoreServerError cosms_core_server_accept(struct cosms_core_server *current_server, struct cosms_core_server_client *client) {
+    client->socket = accept(current_server->listening_socket, (struct sockaddr*)&client->address, &client->address_length);
+    if (client->socket == COSMS_CORE_SERVER_INVALID_SOCKET) {
+        return COSMS_CORE_SERVER_FAILED_TO_ACCEPT;
+    }
+    
+    return COSMS_CORE_SERVER_OK;
+}
+
 /**
  * @brief Receives message from client.
  *
- * @param current_server Pointer to active server struct (must not be NULL)
+ * @param current_server Pointer to an active server struct (must not be NULL)
  * @param client Pointer to client struct (must be connected to server when using tcp)
  * @param buffer to store the received message in (must not be NULL)
  * @param buffer_size the size of the buffer to store the message in
@@ -80,7 +117,7 @@ CosmsCoreServerError cosms_core_server_receive(struct cosms_core_server *current
 /**
  * @brief Sends message to client.
  *
- * @param current_server Pointer to active server struct (must not be NULL)
+ * @param current_server Pointer to an active server struct (must not be NULL)
  * @param client Pointer to client struct (must be connected to server when using tcp)
  * @param buffer containing the message to send to the client
  * @param buffer_size the size of the buffer to send to the client

src/networking/server.c

@@ -7,7 +7,6 @@
  * http://www.apache.org/licenses/LICENSE-2.0
  */
 #include "cosms-core/networking/server.h"
-#include <winsock2.h>
 
 #if defined(__linux__)
 #include <unistd.h>
@@ -40,7 +39,7 @@ CosmsCoreServerError cosms_core_server_create(struct cosms_core_server *new_serv
     #endif
 
     new_server->listening_socket = socket(domain, type, 0);
-    if (new_server->listening_socket == INVALID_SOCKET) {
+    if (new_server->listening_socket == COSMS_CORE_SERVER_INVALID_SOCKET) {
         return COSMS_CORE_SERVER_FAILED_TO_CREATE_SOCKET;
     }
 
@@ -140,6 +139,12 @@ const char *cosms_core_server_error_string(CosmsCoreServerError error) {
         case COSMS_CORE_SERVER_UNKNOWN_ERROR:
             return "cosms-core-server unkown error occured";
 
+        case COSMS_CORE_SERVER_FAILED_TO_ACCEPT:
+            return "cosms-core-server failed to accept new connection";
+
+        case COSMS_CORE_SERVER_COULD_NOT_SET_MODE:
+            return "cosms-core-server could not set mode of server socket";
+
         default:
             return NULL;
     }