socket初学者 数据多次发送接收问题，请高手帮忙。多谢了
代码功能说明：
为了研究下send,recv的同步关系，写了一段代码如下。
connect后，client在 while里send 1,2,3,4,5 5个data, server端在while里读取。
报错：
client端
while start
str= 0,len=1
str= 1,len=1
send出错！: Connection reset by peer
server端
读第一个时就直接报错：“recv出错！: Transport endpoint is not connected”。请高手帮忙解疑释惑。
下面是代码：
//client的
#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 SERVPORT 3333
#define MAXDATASIZE 100 /*每次最大数据传输量 */
//return the length of result string. support only 10 radix for easy use and better performance
int my_itoa(int val, char* buf)
{
const unsigned int radix = 10;
char* p;
unsigned int a; //every digit
int len;
char* b; //start of the digit char
char temp;
unsigned int u;
p = buf;
if (val < 0)
{
*p++ = '-';
val = 0 - val;
}
u = (unsigned int)val;
b = p;
do
{
a = u % radix;
u /= radix;
*p++ = a + '0';
} while (u > 0);
len = (int)(p - buf);
*p-- = 0;
//swap
do
{
temp = *p;
*p = *b;
*b = temp;
--p;
++b;
} while (b < p);
return len;
}
main(int argc, char *argv[]){
int sockfd, recvbytes;
char buf[MAXDATASIZE] = {0};
struct hostent *host;
struct sockaddr_in serv_addr;
int i=0;
if (argc < 2) {
fprintf(stderr,"Please enter the server's hostname! ");
exit(1);
}
if((host=gethostbyname(argv[1]))==NULL) {
herror("gethostbyname出错！");
exit(1);
}
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
perror("socket创建出错！");
exit(1);
}
serv_addr.sin_family=AF_INET;
serv_addr.sin_port=htons(SERVPORT);
serv_addr.sin_addr = *((struct in_addr *)host->h_addr);
bzero(&(serv_addr.sin_zero),8);
if (connect(sockfd, (struct sockaddr *)&serv_addr,sizeof(struct sockaddr)) == -1) {
perror("connect出错！");
exit(1);
}
/* if ((recvbytes=recv(sockfd, buf, MAXDATASIZE, 0)) ==-1) {
perror("recv出错！");
exit(1);
}
buf[recvbytes] = "\0";
printf("Received: %s,recvbytes=%d ",buf,recvbytes);
*/
//printf("cmd is %s, length =%d",argv[2],strlen(argv[2]));
printf("while start \n");
while(i<5)
{
char str[10];
int len;
memset(str,0,10);
len = my_itoa(i,str);
printf("str= %s,len=%d \n",str,len);
if (send(sockfd, str,len+1, 0) == -1)
perror("send出错！");
i++;
sleep(1);
}
printf("while end \n");
close(sockfd);
}
//server端的代码
#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 SERVPORT 3333 /*服务器监听端口号 */
#define BACKLOG 10 /* 最大同时连接请求数 */
#define MAXDATASIZE 100
void main()
{
int sockfd,client_fd; /*sock_fd：监听socket；client_fd：数据传输socket */
struct sockaddr_in my_addr; /* 本机地址信息 */
struct sockaddr_in remote_addr; /* 客户端地址信息 */
int sin_size;
int recvbytes;
char buf[MAXDATASIZE] = {0};
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket创建出错！"); 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出错！");
exit(1);
}
if (listen(sockfd, BACKLOG) == -1) {
perror("listen出错！");
exit(1);
}
//accept
sin_size = sizeof(struct sockaddr_in);
if ((client_fd = accept(sockfd, (struct sockaddr *)&remote_addr, &sin_size)) == -1) {
perror("accept出错");
}
//printf("received a connection from %s ", inet_ntoa(remote_addr.sin_addr));
printf("received a connection from\n");
while(1) {
//recv
memset(buf,0,MAXDATASIZE);
if ((recvbytes=recv(sockfd, buf, MAXDATASIZE, 0)) ==-1) {
perror("recv出错！");
//exit(1);
}
if(recvbytes > 0) // there is data
{
printf("Received: %s,recvbytes=%d \n",buf,recvbytes);
//do something
}
}
}
[解决办法]
请注意你的服务器
if((recvbytes=recv(sockfd, buf, MAXDATASIZE, 0)) ==-1)
这个语句，应该改为
if ((recvbytes=recv(client_fd, buf, MAXDATASIZE, 0)) ==-1)
调用accept函数之后，实际用于通信的fd是client_fd，而sockfd只是用于listen（监听）而已。
linux+gcc 测试传输无误。
[解决办法]
在你的CLIENT端,SEND后面加一个LOG,看是否执行完第一次后,是否走完了SEND吧.
