Linux网络编程--客户端连接服务器端

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

#define MYPORT 3424 // the port users will be connecting to

#define BACKLOG 10 // how many pending connections queue will hold

void sigchld_handler(int s)
{
while(waitpid(-1, NULL, WNOHANG) > 0);//参考：me
}

int main(void)
{
int sockfd, new_fd; // listen on sock_fd, new connection on new_fd

struct sockaddr_in my_addr; // my address information

struct sockaddr_in their_addr; // connector's address information

socklen_t sin_size;
struct sigaction sa;
int yes=1;

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

if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) {
perror("setsockopt");
exit(1);
}

my_addr.sin_family = AF_INET; // host byte order

my_addr.sin_port = htons(MYPORT); // short, network byte order

my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP

memset(my_addr.sin_zero, '/0', sizeof my_addr.sin_zero);

if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof my_addr) == -1) {
perror("bind");
exit(1);
}

if (listen(sockfd, BACKLOG) == -1) {
perror("listen");
exit(1);
}

sa.sa_handler = sigchld_handler; // reap all dead processes

sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if (sigaction(SIGCHLD, &sa, NULL) == -1) {
perror("sigaction");
exit(1);
}

while(1) { // main accept() loop

sin_size = sizeof their_addr;
if ((new_fd = accept(sockfd, (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()) { // this is the child process

close(sockfd); // child doesn't need the listener

if (send(new_fd, "Hello,Liceven!/n", 14, 0) == -1)
perror("send");
close(new_fd);
exit(0);
}
close(new_fd); // parent doesn't need this

}

return 0;
}

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

#define PORT 3424 // the port client will be connecting to

#define MAXDATASIZE 100 // max number of bytes we can get at once

int main(int argc, char *argv[])
{
int sockfd, numbytes;
char buf[MAXDATASIZE];
struct hostent *he;
struct sockaddr_in their_addr; // connector'saddress information

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

if ((he=gethostbyname(argv[1])) == NULL) { // get the host info

herror("gethostbyname");
exit(1);
}

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

their_addr.sin_family = AF_INET; // host byte order

their_addr.sin_port = htons(PORT); // short, network byte order

their_addr.sin_addr = *((struct in_addr *)he->h_addr);
memset(their_addr.sin_zero, '/0', sizeof their_addr.sin_zero);

if (connect(sockfd, (struct sockaddr *)&their_addr,
sizeof their_addr) == -1) {
perror("connect");
exit(1);
}

if ((numbytes=recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
perror("recv");
exit(1);
}

buf[numbytes] = '/0';

printf("Received: %s",buf);

close(sockfd);

return 0;
}