linux socket连接中 ERRNO错误

#include <stdio.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <strings.h>
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <errno.h>
#define PORT 1234
#define SERVER "10.1.70.21" int main()
{
int fd = socket(AF_INET, SOCK_STREAM, );
int nfd;
int ret;
struct sockaddr_in server_addr, client_addr;
bzero(&server_addr, sizeof(server_addr)); server_addr.sin_family =AF_INET;
server_addr.sin_port = htons(PORT);
inet_pton(AF_INET, SERVER, &server_addr.sin_addr);
//bind(fd, (struct sockaddr *)&server_addr, sizeof(server_addr));
errno = ;
ret = connect(fd, (struct sockaddr*)&server_addr, sizeof(server_addr));
if(ret == -)
{
perror("connect: ");
}
char buf[];
while()
{
bzero(buf, );
ret = read(STDIN_FILENO, buf, sizeof(buf));
printf("ret: %d, buf: %s", ret, buf);
ret = write(fd, buf, ret);
printf("ret:%d\n", ret);
if(ret < )
{
perror("write error");
}
ret = read(fd, buf, );
if(ret < )
{
perror("ret");
}
write(STDOUT_FILENO, buf, ret);
}
return ;
}

#include <stdio.h>
#include <sys/types.h> /* See NOTES */
#include <sys/socket.h>
#include <strings.h>
#include <unistd.h>
#include <netinet/in.h>
#include <string.h>
#include <errno.h>
//server端监听端口
#define PORT 3388
int main()
{
int fd = socket(AF_INET, SOCK_STREAM, );//创建一个socket
int nfd;
struct sockaddr_in server_addr, client_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family =AF_INET; //ipv4
server_addr.sin_port = htons(PORT);//端口
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//监听本主机的所有ip bind(fd, (struct sockaddr *)&server_addr, sizeof(server_addr));//绑定
listen(fd, );//监听socket连接，30为三次握手队列大小
char buf[];
// 把server_addr.sin_addr的地址转换成字符串（点分十进制表示）
inet_ntop(AF_INET, &server_addr.sin_addr, buf, sizeof(buf));
printf("%s\n", buf);//一般输出为0.0.0.0
pid_t pid;
while()
{
bzero(buf, sizeof(buf));//buf清零，相当于memset(buf, 0, sizeof(buf)); socklen_t len= sizeof(client_addr);
nfd = accept(fd, (struct sockaddr*)&client_addr, &len);//接收socket连接
inet_ntop(AF_INET, &client_addr.sin_addr, buf, sizeof(buf));//获取socket连接客户端的ip
printf("accept connetc %s port %d\n", buf, ntohs(client_addr.sin_port)); pid = fork();
//子进程
if(pid == )
{
while()
{ int ret = read(nfd, buf, sizeof(buf));
if(ret <= )
{
perror("ret");
return ;
}
write(STDOUT_FILENO, buf, ret);
write(nfd, buf, ret);
}
}
}
return ;
}