无法通过套接字发送或接收数据

我尝试制作一个简单的服务器-客户端套接字通信，但服务器似乎无法正常工作。无论何时发送或接收，我都会收到此错误：

非套接字上的套接字操作：非套接字上的套接字运算

奇怪的是，这只会在服务器发送时出现。客户端似乎还好：

//server
#include <iostream>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <arpa/inet.h>
using namespace std;
int main(){
const int PORT = 5000;
int serverfd, clientfd, opt=1, n_send, n_recv;
sockaddr_in server_address, client_address;
char recvbuf[1024], sendbuf[1024];
bzero(&server_address , sizeof(server_address));
inet_pton(AF_INET, "127.0.0.1",&server_address.sin_addr);
int x = INADDR_ANY;
server_address.sin_family = AF_INET;
server_address.sin_port = htons(PORT);
socklen_t addrSize = sizeof(server_address);
if((serverfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
if((setsockopt(serverfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) < 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
if((bind(serverfd, (sockaddr*)&server_address, sizeof(server_address)))< 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
if((listen(serverfd, 1))< 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
if((clientfd = accept(serverfd, (sockaddr *)&server_address, (socklen_t*)&addrSize) < 0)){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
while (true){
cout << "SAY TO CLIENT: ";
bzero(sendbuf, sizeof(sendbuf));
cin >> sendbuf;
cout << endl;
send(clientfd, sendbuf, strlen(sendbuf), 0);
errno = 0;
bzero(recvbuf, sizeof(recvbuf));
if((n_recv = recv(clientfd, recvbuf, sizeof(recvbuf), MSG_WAITALL))< 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
cout << recvbuf << endl;
}
return 0;
}

//client
#include <iostream>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <arpa/inet.h>
using namespace std;
int main(){
const int PORT = 5000;
int sockfd, n_send, n_recv;
char recvbuf[1024], sendbuf[1024];
sockaddr_in server_address;
bzero(&server_address, sizeof(server_address));
server_address.sin_family= AF_INET;
server_address.sin_port = htons(PORT);
inet_pton(AF_INET, "127.0.0.1", &server_address.sin_addr);
if((sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
if(connect(sockfd, (sockaddr *) &server_address, sizeof(server_address))<0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
while (true){
if((n_recv = recv(sockfd, recvbuf, sizeof(recvbuf), MSG_WAITALL)) < 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
cout << "Server: " << recvbuf << endl;
cout << "Say to server: ";
cin >> sendbuf;
cout << endl;
if((n_send = send(sockfd, sendbuf, sizeof(sendbuf), 0)) < 0){
perror(strerror(errno));
exit(EXIT_FAILURE);
}
}
return 0;
}