feat(server): added receive function for udp and tcp servers

include/cosms-core/networking/server.h

@@ -16,10 +16,13 @@
 #endif
 
 typedef enum {
+    COSMS_CORE_SERVER_CONNECTION_CLOSED = 1,
     COSMS_CORE_SERVER_OK = 0,
     COSMS_CORE_SERVER_FAILED_TO_CREATE_SOCKET = -1,
     COSMS_CORE_SERVER_COULD_NOT_BIND_ADDRESS = -2,
-    COSMS_CORE_SERVER_UNKNOWN_ERROR = -3
+    COSMS_CORE_SERVER_UNKNOWN_ERROR = -3,
+    COSMS_CORE_SERVER_TYPE_NOT_SUPPORTED = -4,
+    COSMS_CORE_SERVER_FAILED_TO_RECEIVE = -5
 } CosmsCoreServerError;
 
 struct cosms_core_server {
@@ -33,6 +36,17 @@ struct cosms_core_server {
     #endif
 };
 
+struct cosms_core_server_client {
+    struct sockaddr_in address;
+    int address_length;
+    
+    #if defined(__linux__)
+    int socket;
+    #elif defined(_WIN32)
+    SOCKET socket;
+    #endif  
+};
+
 /**
  * @brief Creates a new server of specified type.
  *
@@ -51,6 +65,18 @@ CosmsCoreServerError cosms_core_server_create(struct cosms_core_server *new_serv
  */
 CosmsCoreServerError cosms_core_server_destroy(struct cosms_core_server *current_server);
 
+/**
+ * @brief Receives message from client.
+ *
+ * @param current_server Pointer to 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
+ * @param received_bytes the amount of bytes received from the client (can be NULL)
+ * @return COSMS_CORE_SERVER_OK or COSMS_CORE_SERVER_CONNECTION_CLOSED on success, or negative error code
+ */
+CosmsCoreServerError cosms_core_server_receive(struct cosms_core_server *current_server, struct cosms_core_server_client *client, char *buffer, unsigned int buffer_size, unsigned int *received_bytes);
+
 /**
  * @brief Converts error code to a string that can be used for printing/logging errors.
  *

src/networking/server.c

@@ -7,6 +7,7 @@
  * http://www.apache.org/licenses/LICENSE-2.0
  */
 #include "cosms-core/networking/server.h"
+#include <winsock2.h>
 
 #if defined(__linux__)
 #include <unistd.h>
@@ -27,17 +28,7 @@ CosmsCoreServerError cosms_core_server_create(struct cosms_core_server *new_serv
     address.sin_addr.s_addr = INADDR_ANY;
     address.sin_port = htons(port);
 
-    #if defined(__linux__)
+    #if defined(_WIN32)
-    new_server->listening_socket = socket(domain, type, 0);
-    if (new_server->listening_socket == -1) {
-        return COSMS_CORE_SERVER_FAILED_TO_CREATE_SOCKET;
-    }
-
-    int result = bind(new_server->listening_socket, (struct sockaddr*)&address, sizeof(address));
-    if (result == -1) {
-        return COSMS_CORE_SERVER_COULD_NOT_BIND_ADDRESS;
-    }
-    #elif defined(_WIN32)
     if (cosms_core_server_initialized_winsock_instances == 0) {
         WSADATA data;
         if (WSAStartup(MAKEWORD(2, 2), &data) == 0) {
@@ -46,6 +37,7 @@ CosmsCoreServerError cosms_core_server_create(struct cosms_core_server *new_serv
     }
 
     cosms_core_server_initialized_winsock_instances += 1;
+    #endif
 
     new_server->listening_socket = socket(domain, type, 0);
     if (new_server->listening_socket == INVALID_SOCKET) {
@@ -53,10 +45,9 @@ CosmsCoreServerError cosms_core_server_create(struct cosms_core_server *new_serv
     }
 
     int result = bind(new_server->listening_socket, (struct sockaddr*)&address, sizeof(address));
-    if (result == SOCKET_ERROR) {
+    if (result == -1) {
         return COSMS_CORE_SERVER_COULD_NOT_BIND_ADDRESS;
     }
-    #endif
 
     return COSMS_CORE_SERVER_OK;
 }
@@ -85,11 +76,40 @@ CosmsCoreServerError cosms_core_server_destroy(struct cosms_core_server *current
     return COSMS_CORE_SERVER_OK;
 }
 
+/**
+ * @brief Receives message from client.
+ */
+CosmsCoreServerError cosms_core_server_receive(struct cosms_core_server *current_server, struct cosms_core_server_client *client, char *buffer, unsigned int buffer_size, unsigned int *received_bytes) {
+    int bytes_received = 0;
+    if (current_server->type == SOCK_STREAM) {
+        bytes_received = recv(client->socket, buffer, buffer_size, 0);
+    } else {
+        bytes_received = recvfrom(current_server->listening_socket, buffer, buffer_size, 0, (struct sockaddr*)&client->address, &client->address_length);
+    }
+
+    if (bytes_received == -1) {
+        return COSMS_CORE_SERVER_FAILED_TO_RECEIVE;
+    } 
+    
+    if (bytes_received == 0) {
+        return COSMS_CORE_SERVER_CONNECTION_CLOSED;
+    }
+
+    if (received_bytes != NULL) {
+        (*received_bytes) = bytes_received;
+    }
+
+    return COSMS_CORE_SERVER_OK;
+}
+
 /**
  * @brief Converts error code to a string that can be used for printing/logging errors.
  */
 const char *cosms_core_server_error_string(CosmsCoreServerError error) {
     switch (error) {
+        case COSMS_CORE_SERVER_CONNECTION_CLOSED:
+            return "cosms-core-server connection was closed";
+
         case COSMS_CORE_SERVER_OK:
             return "cosms-core-server everything ok";