client.c

linuxFedure4环境下串口编程后台运行状态机

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 

void error(char *msg)
{
		perror(msg);
		exit(0);
}

int main(int argc, char *argv[])
{
		int sockfd, portno, n;
		struct sockaddr_in serv_addr;
		struct hostent *server;

		char buffer[256];
		if (argc < 3) {
				fprintf(stderr,"usage %s hostname port\n", argv[0]);
				exit(0);
		}
		portno = atoi(argv[2]);
		sockfd = socket(AF_INET, SOCK_STREAM, 0);
		if (sockfd < 0) 
				error("ERROR opening socket");
		server = gethostbyname(argv[1]);
		if (server == NULL) {
				fprintf(stderr,"ERROR, no such host\n");
				exit(0);
		}
		bzero((char *) &serv_addr, sizeof(serv_addr));
		serv_addr.sin_family = AF_INET;
		bcopy((char *)server->h_addr, 
						(char *)&serv_addr.sin_addr.s_addr,
						server->h_length);
		serv_addr.sin_port = htons(portno);
		if (connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0) 
				error("ERROR connecting");
		printf("Please enter the message: ");
		bzero(buffer,256);
		fgets(buffer,255,stdin);
		n = write(sockfd,buffer,strlen(buffer));
		if (n < 0) 
				error("ERROR writing to socket");
		bzero(buffer,256);
		n = read(sockfd,buffer,255);
		if (n < 0) 
				error("ERROR reading from socket");
		printf("%s\n",buffer);
		return 0;
}