linux 通信几例

//命令lsof -i:5999

//简单服务器

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>

#define MYPORT 5999

#define BACKLOG 10

int main(){
	int sock_fd, new_fd;
	struct sockaddr_in my_addr, their_addr;
	int sin_size;
	if((sock_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
		perror("socket");
		exit(1);
	}
	my_addr.sin_family = AF_INET;
	my_addr.sin_port = htons(MYPORT);
	my_addr.sin_addr.s_addr = INADDR_ANY;

	bzero(&(my_addr.sin_zero), 8);
	if(bind(sock_fd, (struct sockaddr*)&my_addr, sizeof(struct sockaddr)) == -1){
		perror("bind");
		exit(1);
	}
	if(listen(sock_fd, BACKLOG) == -1){
		perror("listen");
		exit(1);
	}
	while(1){
		sin_size = sizeof(struct sockaddr_in);
		if((new_fd = accept(sock_fd, (struct sockaddr *)&their_addr, &sin_size)) == -1){
			perror("accept");
			continue;
		}
		printf("server.got connection from %s\n",inet_ntoa(their_addr.sin_addr));
		if(!fork()){
			if(send(new_fd, "Hello,world!\n", 14, 0) == -1){
				perror("send");
				close(new_fd);
				exit(0);
			}
		}
		while(waitpid(-1, NULL, WNOHANG) > 0);
	}
}

//简单客户端

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

#define PORT 5999

#define MAXDATASIZE 100

int main(int argc, char *argv[]){
	int sockfd, numbytes;
	char buf[MAXDATASIZE];

	struct hostent *he;
	struct sockaddr_in their_addr;

	if(argc != 2){
		fprintf(stderr, "usage: client hostname\n");
		exit(1);
	}

	if((he = gethostbyname(argv[1])) == NULL){
		perror("gethostbyname");
		exit(1);
	}
//	printf();

	if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
		perror("socket");
		exit(1);
	}

	their_addr.sin_family = AF_INET;
	their_addr.sin_port = htons(PORT);

	//their_addr.sin_addr = *((struct in_addr*)he->h_addr);
	their_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
	bzero(&(their_addr.sin_zero), 8);

	if(connect(sockfd, (struct sockaddr *)&their_addr, sizeof(struct sockaddr)) == -1){
		perror("connect");
		exit(1);
	}
	if((numbytes = recv(sockfd, buf, MAXDATASIZE, 0)) == -1){
		perror("recv");
		exit(1);
	}
	buf[numbytes] = '\0';
	printf("Received: %s", buf);
	close(sockfd);
	return 0;
}

//epoll 服务器端

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/epoll.h>
#include <sys/wait.h>

#define SERVPORT 5999
#define BACKLOG 10 //最大同时连接请求数

void setnonblocking(int sock){
	int opts;
	opts = fcntl(sock, F_GETFL);
	if(opts < 0){
		perror("fcntl(sock, GETFL)");
		exit(1);
	}
	opts = opts | O_NONBLOCK;
	if(fcntl(sock, F_SETFL, opts) < 0){
		perror("fcntl(sock, SETFL, opts)");
		exit(1);
	}
}

void do_use_fd(int client_fd){
	char msg[50];
	const char str[] = "God bless you!\n";
	recv(client_fd, msg, 50, 0);
	printf("get from client msg %s\n", msg);
	if(send(client_fd, str, sizeof(str), 0) == -1)
			perror("send");
	close(client_fd);
}

int main(){
	int sockfd;
	struct sockaddr_in my_addr;
	struct sockaddr_in their_addr;
	
	if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
		perror("socket");
		exit(1);
	}
	my_addr.sin_family = AF_INET;
	my_addr.sin_port = htons(SERVPORT);
	my_addr.sin_addr.s_addr = INADDR_ANY;
	bzero(&(my_addr.sin_zero), 8);
	if(bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1){
		perror("bind");
		exit(1);
	}
	if(listen(sockfd, BACKLOG) == -1){
		perror("listen");
		exit(1);
	}
	size_t sin_size = sizeof(struct sockaddr_in);
	#define MAX_EVENTS 10
	struct epoll_event ev, events[MAX_EVENTS];
	int conn_sock, nfds, epollfd;

	epollfd = epoll_create(10);
	if(epollfd == -1){
		perror("epoll_create");
		exit(EXIT_FAILURE);
	}
	ev.events = EPOLLIN;
	ev.data.fd = sockfd;
	if(epoll_ctl(epollfd, EPOLL_CTL_ADD, sockfd, &ev) == -1){
		perror("epoll_ctl: sockfd");
		exit(EXIT_FAILURE);
	}
	for(;;){
		nfds = epoll_wait(epollfd, events, MAX_EVENTS, -1);
		if(nfds == -1){
			perror("epoll_wait");
			exit(EXIT_FAILURE);
		}
		int i;
		for(i = 0; i < nfds; ++i){
			if(events[i].data.fd == sockfd){
				conn_sock = accept(sockfd,
						(struct sockaddr *)&their_addr, &sin_size);
				if(conn_sock == -1){
					perror("accept");
					exit(EXIT_FAILURE);
				}
				setnonblocking(conn_sock);
				ev.events = EPOLLIN | EPOLLET;
				ev.data.fd = conn_sock;
				if(epoll_ctl(epollfd, EPOLL_CTL_ADD, conn_sock,
							&ev) == -1){
						perror("epoll_ctl: conn_sock");
						exit(EXIT_FAILURE);
				}
			}else{
				do_use_fd(events[i].data.fd);
			}
		}
	}
}

//epoll 客户端
#include <stdio.h>
#include <errno.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <string.h>
#define PORT 5999
#define MSG 50
int main(){
	int sockfd;
	char msg[MSG];
	struct sockaddr_in their_addr;
	if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
		perror("socket() failed");
		exit(1);
	}
	their_addr.sin_family = AF_INET;
	their_addr.sin_port = htons(PORT);
	their_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
	bzero(&their_addr.sin_zero, 8);
	if(connect(sockfd, (struct sockaddr *)&their_addr, sizeof(struct sockaddr)) == -1){
		perror("connect error");
		exit(1);
	}
	send(sockfd, "HELLO", 20, 0);
	recv(sockfd, msg, MSG, 0);
	printf("%s\n", msg);
	close(sockfd);
}

//管道

#include <stdlib.h>
#include <time.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#define MAXMSG 0xff


int main(){
	int fd_req[2];/*声明了两个管道描述符，一个用来发询问信息*/
	int fd_ans[2];/*       一个用来回答                  */
	pid_t pid;
	char msg[MAXMSG];
	
	if(pipe(fd_req) < 0 || pipe(fd_ans) < 0){
		perror("init pipe fault...\n");
		return -1;
	}
	
	if((pid = fork()) < 0){
		perror("init fork fault...\n");
	}
	
	if(pid > 0){//father process
		close(fd_req[1]);
		close(fd_ans[0]);
		int res, ask;
		printf("Enter a number between 1-1000: ");
		scanf("%d", &res);                        //输入答案
		write(fd_ans[1], "start", MAXMSG);        //给子进程解锁
		while(1){
			read(fd_req[0], msg, MAXMSG);
			if(strcmp(msg, "end") == 0){          //结束标识，则结束。
				close(fd_req[0]);
				close(fd_ans[1]);
				return 0;
			}
			ask = atoi(msg);
			if(res > ask)
				write(fd_ans[1], "yes", MAXMSG);
			else
				write(fd_ans[1], "no", MAXMSG);
		}
	}else{
		int from = 0, to = 1024, mid;
		read(fd_ans[0], msg, MAXMSG);           //首先阻塞子进程，直到父进程发消息
		while(1){
			 mid = (from + to) / 2;
			 sprintf(msg, "%d", mid);
			 
			 write(fd_req[1], msg, MAXMSG); //询问
			 printf("Is the number bigger than %d(yes/no)?\n", mid);
			 
			 read(fd_ans[0], msg, MAXMSG);  //回答
			 printf("%s\n", msg);
			 
			 if(strcmp(msg, "yes") == 0)
			 	from = mid;
			 else
			 	to = mid;

			 if(from + 1 == to){
			 	printf("I have succeeded in guessing your number!  ans = %d\n", to);
			 	write(fd_req[1], "end", MAXMSG);
			 	return ;
			 }
		}
	}
}

#include <stdio.h>
#include <pthread.h>
#include <errno.h>
#include <semaphore.h>
#include <stdlib.h>

#define TIME1 200
#define TIME2 199

int apple_num(int from, int to){
	if(to >= from)
		return to - from;
	return to + 6 - from;
}

sem_t sem_apple, sem_space;
pthread_mutex_t producer_mutex, customer_mutex;
int from = 0, to = 0;
void * producer(void *args){
	int time = TIME1;
	while(time--){
		pthread_mutex_lock(&producer_mutex);
		sem_wait(&sem_space);
		to = (to + 1) % 6;
		printf("生产一个，当前苹果数目%d个\n", apple_num(from, to));
		sem_post(&sem_apple);
		pthread_mutex_unlock(&producer_mutex);
	}
}
void * customer(void *args){
	int time = TIME2;
	while(time--){
		pthread_mutex_lock(&customer_mutex);
		sem_wait(&sem_apple);
		from = (from + 1) % 6;
		printf("消费一个，当前苹果数目%d个\n", apple_num(from, to));
		sem_post(&sem_space);
		pthread_mutex_unlock(&customer_mutex);
	}
}
int main(){
	
	pthread_t id1[3], id2[3];
	//int ret1, ret2;
	sem_init(&sem_apple, 0, 0);
	sem_init(&sem_space, 0, 5);
	pthread_mutex_init(&producer_mutex, NULL);
	pthread_mutex_init(&customer_mutex, NULL);
	int i;
	for(i = 0; i < 3; i++){
		if(pthread_create(&id1[i], NULL, (void *)producer, NULL) != 0){
			perror("pthread_create()");
			exit(1);		
		}
		if(pthread_create(&id2[i], NULL, (void *)customer, NULL) != 0){
			perror("pthread_create()");
			exit(1);
		}
	}

	for(i = 0; i < 3; i++){
		pthread_join(id1[i], NULL);
		pthread_join(id2[i], NULL);
	}
	sem_destroy(&sem_apple);
	sem_destroy(&sem_space);
        return 0;
}