/*********************************************************************************
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* Copyright: (C) 2025 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: socket.c
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* Description: This file is TCP socket client example program.
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*
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* Version: 1.0.0(10/20/2025)
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* Author: Guo Wenxue <guowenxue@gmail.com>
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* ChangeLog: 1, Release initial version on "10/20/2025 09:48:51 PM"
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*
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********************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <unistd.h>
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#include <math.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <getopt.h>
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void print_usage(char *progname)
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{
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printf("%s usage: \n", progname);
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printf(" -i(--ipaddr): sepcify server IP address\n");
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printf(" -p(--port): sepcify server port.\n");
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printf(" -h(--Help): print this help information.\n");
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return ;
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}
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int main(int argc, char **argv)
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{
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int conn_fd = -1;
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int rv = -1;
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char buf[1024];
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char *servip = "127.0.0.1";
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int port = 0;
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struct sockaddr_in serv_addr;
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int ch;
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struct option opts[] = {
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{"ipaddr", required_argument, NULL, 'i'},
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{"port", required_argument, NULL, 'p'},
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{"help", no_argument, NULL, 'h'},
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{NULL, 0, NULL, 0}
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};
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/* parser command line input arguments */
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while( (ch=getopt_long(argc, argv, "i:p:h", opts, NULL)) != -1 )
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{
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switch(ch)
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{
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case 'i':
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servip=optarg;
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break;
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case 'p':
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port=atoi(optarg);
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break;
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case 'h':
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print_usage(argv[0]);
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return 0;
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}
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}
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/* socket client must specify server IP address and port */
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if( !servip || !port )
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{
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print_usage(argv[0]);
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return 1;
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}
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/* create TCP socket */
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conn_fd = socket(AF_INET, SOCK_STREAM, 0);
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if(conn_fd < 0)
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{
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printf("create socket failure: %s\n", strerror(errno));
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return 2;
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}
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/* set server IP address and port into $server_addr */
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memset(&serv_addr, 0, sizeof(serv_addr));
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serv_addr.sin_family = AF_INET;
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serv_addr.sin_port = htons(port);
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inet_aton( servip, &serv_addr.sin_addr );
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/* connect to socket server */
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if( connect(conn_fd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
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{
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printf("connect to server [%s:%d] failure: %s\n", servip, port, strerror(errno));
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return 3;
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}
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while(1)
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{
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/* send message to socket server */
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strncpy(buf, "Hello, LingYun IoT socket server!\n", sizeof(buf));
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if( write(conn_fd, buf, strlen(buf)) < 0 )
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{
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printf("Write data to server [%s:%d] failure: %s\n", servip, port, strerror(errno));
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goto cleanup;
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}
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printf("Send message to socket server okay\n");
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/* receive message from socket server */
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printf("Wating reply from socket server...\n");
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memset(buf, 0, sizeof(buf));
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rv = read(conn_fd, buf, sizeof(buf));
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if(rv < 0)
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{
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printf("Read data from server failure: %s\n", strerror(errno));
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goto cleanup;
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}
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else if( 0 == rv )
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{
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printf("Client connect to server get disconnected\n");
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goto cleanup;
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}
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printf("Receive [%d] bytes data from server: %s", rv, buf);
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printf("\n");
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sleep(3);
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}
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cleanup:
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close(conn_fd);
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return 0;
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}
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