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/*
* Copyright © 2008-2014 Stéphane Raimbault <stephane.raimbault@gmail.com>
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#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/select.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#endif
#define NB_CONNECTION 5
static modbus_t *ctx = NULL;
static modbus_mapping_t *mb_mapping;
static int server_socket = -1;
static void close_sigint(int dummy)
{
if (server_socket != -1) {
close(server_socket);
}
modbus_free(ctx);
modbus_mapping_free(mb_mapping);
exit(dummy);
}
int main(void)
{
uint8_t query[MODBUS_TCP_MAX_ADU_LENGTH];
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);
if (server_socket == -1) {
fprintf(stderr, "Unable to listen TCP connection\n");
modbus_free(ctx);
return -1;
}
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)) {
continue;
}
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 {
modbus_set_socket(ctx, master_socket);
rc = modbus_receive(ctx, query);
if (rc > 0) {
modbus_reply(ctx, query, rc, mb_mapping);
} else if (rc == -1) {
/* This example server in ended on connection closing or
* any errors. */
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;
}
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