/*
                       SERVIDOR
                   */
                    
                   #include <stdio.h>
                   #include <stdlib.h>
                   #include <string.h>
                   #include <winsock.h>
                    
               #define BACKLOG_MAX 5
               #define BUFFER_SIZE 128
               #define EXIT_CALL_STRING "#quit"
                
               int local_socket = 0;
               int remote_socket = 0;
                
               int remote_length = 0;
               int message_length = 0;
                
               unsigned short local_port = 0;
               unsigned short remote_port = 0;
                
               char message[BUFFER_SIZE];
                
               struct sockaddr_in local_address;
               struct sockaddr_in remote_address;
                
               WSADATA wsa_data;
                
               /* Exibe uma mensagem de erro e termina o programa */
               void msg_err_exit(char *msg)
               {
                   fprintf(stderr, msg);
                   system("PAUSE");
                   exit(EXIT_FAILURE);
               }
                
               int main(int argc, char **argv)
               {
                   // inicia o Winsock 2.0 (DLL), Only for Windows
                   if (WSAStartup(MAKEWORD(2, 0), &wsa_data) != 0)
                       printf("WSAStartup() failed\n");
                
                   // criando o socket local para o servidor
                   local_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
                   if (local_socket == INVALID_SOCKET)
                   {
                       WSACleanup();
                       printf("socket() failed\n");
                   }
                
                   printf("Porta local: ");
                   scanf("%d", &local_port);
                   fflush(stdin);
                
                   // zera a estrutura local_address
                   memset(&local_address, 0, sizeof(local_address));
                
                   // internet address family
                   local_address.sin_family = AF_INET;
                
                   // porta local
                   local_address.sin_port = htons(local_port);
                
                   // endereco
                   local_address.sin_addr.s_addr = htonl(INADDR_ANY); // inet_addr("127.0.0.1")
                
                   // interligando o socket com o endereço (local)
                   if (bind(local_socket, (struct sockaddr *) &local_address, sizeof(local_address)) == SOCKET_ERROR)
                   {
                       WSACleanup();
                       closesocket(local_socket);
                       printf("bind() failed\n");
                   }
                
                  // coloca o socket para escutar as conexoes
                   if (listen(local_socket, BACKLOG_MAX) == SOCKET_ERROR)
                   {
                       WSACleanup();
                       closesocket(local_socket);
                       printf("listen() failed\n");
                   }
                
                   remote_length = sizeof(remote_address);
                
                   printf("aguardando alguma conexao...\n");
                   remote_socket = accept(local_socket, (struct sockaddr *) &remote_address, &remote_length);
                   if(remote_socket == INVALID_SOCKET)
                   {
                       WSACleanup();
                       closesocket(local_socket);
                       printf("accept() failed\n");
                   }
                
                   printf("conexao estabelecida com %s\n", inet_ntoa(remote_address.sin_addr));
                   printf("aguardando mensagens...\n");
                   do
                   {
                       // limpa o buffer
                   memset(&message, 0, BUFFER_SIZE);
            
                  // recebe a mensagem do cliente
                   message_length = recv(remote_socket, message, BUFFER_SIZE, 0);
                   if(message_length == SOCKET_ERROR)
                       printf("recv() failed\n");
           
                   // exibe a mensagem na tela
                   printf("%s: %s\n", inet_ntoa(remote_address.sin_addr), message);
               }
               while(strcmp(message, EXIT_CALL_STRING)); // sai quando receber um "#quit" do cliente
            
               printf("encerrando\n");
               WSACleanup();
               closesocket(local_socket);
               closesocket(remote_socket);
            
               system("PAUSE");
               return 0;
           }