Modbus TCP客户端和服务器示例

/* TCP Echo server example in winsock Live Server on port 8888 */ #include<stdio.h> #include<winsock2.h> #include "mbconfig.h" #pragma comment(lib, "ws2_32.lib") //Winsock Library int main(int argc, char* argv[]) { WSADATA wsa; SOCKET master, new_socket, client_socket[30], s; struct sockaddr_in server, address; int max_clients = 30, activity, addrlen, i, valread; char* message = "ECHO Daemon v1.0 \r\n"; int sendLen = 0; //size of our receive buffer, this is string length. int MAXRECV = 1024; //set of socket descriptors fd_set readfds; //1 extra for null character, string termination //char* buffer; //char* sendBuf; //buffer = (char*)malloc((MAXRECV + 1) * sizeof(char)); //sendBuf = (char*)malloc((MAXRECV + 1) * sizeof(char)); uint8_t buffer[50]; uint8_t sendBuf[50]; for (i = 0; i < 30; i++) { client_socket[i] = 0; } printf("\nInitialising Winsock..."); if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0) { printf("Failed. Error Code : %d", WSAGetLastError()); exit(EXIT_FAILURE); } printf("Initialised.\n"); //Create a socket if ((master = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) { printf("Could not create socket : %d", WSAGetLastError()); exit(EXIT_FAILURE); } printf("Socket created.\n"); //Prepare the sockaddr_in structure server.sin_family = AF_INET; server.sin_addr.s_addr = INADDR_ANY; server.sin_port = htons(502); //Bind if (bind(master, (struct sockaddr*)&server, sizeof(server)) == SOCKET_ERROR) { printf("Bind failed with error code : %d", WSAGetLastError()); exit(EXIT_FAILURE); } puts("Bind done"); //Listen to incoming connections listen(master, 3); //Accept and incoming connection puts("Waiting for incoming connections..."); addrlen = sizeof(struct sockaddr_in); while (TRUE) { //clear the socket fd set FD_ZERO(&readfds); //add master socket to fd set FD_SET(master, &readfds); //add child sockets to fd set for (i = 0; i < max_clients; i++) { s = client_socket[i]; if (s > 0) { FD_SET(s, &readfds); } } //wait for an activity on any of the sockets, timeout is NULL , so wait indefinitely activity = select(0, &readfds, NULL, NULL, NULL); if (activity == SOCKET_ERROR) { printf("select call failed with error code : %d", WSAGetLastError()); exit(EXIT_FAILURE); } //If something happened on the master socket , then its an incoming connection if (FD_ISSET(master, &readfds)) { if ((new_socket = accept(master, (struct sockaddr*)&address, (int*)&addrlen)) < 0) { perror("accept"); exit(EXIT_FAILURE); } //inform user of socket number - used in send and receive commands printf("New connection , socket fd is %d , ip is : %s , port : %d \n", new_socket, inet_ntoa(address.sin_addr), ntohs(address.sin_port)); //send new connection greeting message if (send(new_socket, message, strlen(message), 0) != strlen(message)) { perror("send failed"); } puts("Welcome message sent successfully"); //add new socket to array of sockets for (i = 0; i < max_clients; i++) { if (client_socket[i] == 0) { client_socket[i] = new_socket; printf("Adding to list of sockets at index %d \n", i); break; } } } //else its some IO operation on some other socket :) for (i = 0; i < max_clients; i++) { s = client_socket[i]; //if client presend in read sockets if (FD_ISSET(s, &readfds)) { //get details of the client getpeername(s, (struct sockaddr*)&address, (int*)&addrlen); //Check if it was for closing , and also read the incoming message //recv does not place a null terminator at the end of the string (whilst printf %s assumes there is one). valread = recv(s, buffer, MAXRECV, 0); if (valread == SOCKET_ERROR) { int error_code = WSAGetLastError(); if (error_code == WSAECONNRESET) { //Somebody disconnected , get his details and print printf("Host disconnected unexpectedly , ip %s , port %d \n", inet_ntoa(address.sin_addr), ntohs(address.sin_port)); //Close the socket and mark as 0 in list for reuse closesocket(s); client_socket[i] = 0; } else { printf("recv failed with error code : %d", error_code); } } if (valread == 0) { //Somebody disconnected , get his details and print printf("Host disconnected , ip %s , port %d \n", inet_ntoa(address.sin_addr), ntohs(address.sin_port)); //Close the socket and mark as 0 in list for reuse closesocket(s); client_socket[i] = 0; } //Echo back the message that came in else { //add null character, if you want to use with printf/puts or other string handling functions buffer[valread] = '\0'; /*printf("%s:%d - %s \n", inet_ntoa(address.sin_addr), ntohs(address.sin_port), buffer); send(s, buffer, valread, 0);*/ sendLen = ParsingClientAccessCommand(buffer, sendBuf); send(s, sendBuf, sendLen, 0); printf("接收到的数据长度：%d ，发送的数据长度：%d\n", valread, sendLen); } } } } closesocket(s); WSACleanup(); return 0; }