/* * Copyright © 2009-2010 Stéphane Raimbault <stephane.raimbault@gmail.com> * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <stdio.h> #include <unistd.h> #include <string.h> #include <stdlib.h> #include <errno.h> #include <signal.h> #include <modbus.h> #if defined(_WIN32) #include <ws2tcpip.h> #else #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #endif #define NB_CONNECTION 5 modbus_t *ctx = NULL; int server_socket; modbus_mapping_t *mb_mapping; static void close_sigint(int dummy) { close(server_socket); modbus_free(ctx); modbus_mapping_free(mb_mapping); exit(dummy); } int main(void) { int master_socket; int rc; fd_set refset; fd_set rdset; /* Maximum file descriptor number */ int fdmax; ctx = modbus_new_tcp("127.0.0.1", 1502); mb_mapping = modbus_mapping_new(MODBUS_MAX_READ_BITS, 0, MODBUS_MAX_READ_REGISTERS, 0); if (mb_mapping == NULL) { fprintf(stderr, "Failed to allocate the mapping: %s\n", modbus_strerror(errno)); modbus_free(ctx); return -1; } server_socket = modbus_tcp_listen(ctx, NB_CONNECTION); signal(SIGINT, close_sigint); /* Clear the reference set of socket */ FD_ZERO(&refset); /* Add the server socket */ FD_SET(server_socket, &refset); /* Keep track of the max file descriptor */ fdmax = server_socket; for (;;) { rdset = refset; if (select(fdmax+1, &rdset, NULL, NULL, NULL) == -1) { perror("Server select() failure."); close_sigint(1); } /* Run through the existing connections looking for data to be * read */ for (master_socket = 0; master_socket <= fdmax; master_socket++) { if (FD_ISSET(master_socket, &rdset)) { if (master_socket == server_socket) { /* A client is asking a new connection */ socklen_t addrlen; struct sockaddr_in clientaddr; int newfd; /* Handle new connections */ addrlen = sizeof(clientaddr); memset(&clientaddr, 0, sizeof(clientaddr)); newfd = accept(server_socket, (struct sockaddr *)&clientaddr, &addrlen); if (newfd == -1) { perror("Server accept() error"); } else { FD_SET(newfd, &refset); if (newfd > fdmax) { /* Keep track of the maximum */ fdmax = newfd; } printf("New connection from %s:%d on socket %d\n", inet_ntoa(clientaddr.sin_addr), clientaddr.sin_port, newfd); } } else { /* An already connected master has sent a new query */ uint8_t query[MODBUS_TCP_MAX_ADU_LENGTH]; modbus_set_socket(ctx, master_socket); rc = modbus_receive(ctx, query); if (rc != -1) { modbus_reply(ctx, query, rc, mb_mapping); } else { /* Connection closed by the client, end of server */ printf("Connection closed on socket %d\n", master_socket); close(master_socket); /* Remove from reference set */ FD_CLR(master_socket, &refset); if (master_socket == fdmax) { fdmax--; } } } } } } return 0; }