从服务器发送到客户端
每当客户端执行recv()命令时,我都试图从服务器向客户端发送数据。由于现在的代码,我无法让客户打印它收到的任何数据。我无法弄清楚我的服务器或客户端是否有问题,所以我们将不胜感激。谢谢!从服务器发送到客户端
client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#define ECHO_PORT 9999
#define BUF_SIZE 4096
int main(int argc, char* argv[])
{
if (argc != 3)
{
fprintf(stderr, "usage: %s <server-ip> <port>",argv[0]);
return EXIT_FAILURE;
}
char buf[BUF_SIZE];
int status, sock, sock2;
struct addrinfo hints;
memset(&hints, 0, sizeof(struct addrinfo));
struct addrinfo *servinfo; //will point to the results
hints.ai_family = AF_INET; //IPv4
hints.ai_socktype = SOCK_STREAM; //TCP stream sockets
hints.ai_flags = AI_PASSIVE; //fill in my IP for me
if ((status = getaddrinfo(argv[1], argv[2], &hints, &servinfo)) != 0)
{
fprintf(stderr, "getaddrinfo error: %s \n", gai_strerror(status));
return EXIT_FAILURE;
}
if ((sock = socket(servinfo->ai_family, servinfo->ai_socktype, servinfo->ai_protocol)) == -1)
{
fprintf(stderr, "Socket failed");
return EXIT_FAILURE;
}
if ((connect(sock, (struct sockaddr *) servinfo->ai_addr, servinfo->ai_addrlen)) != 0)
{
fprintf(stderr, "Connection failed");
return EXIT_FAILURE;
}
if ((sock2 = socket(servinfo->ai_family, servinfo->ai_socktype, servinfo->ai_protocol)) == -1)
{
fprintf(stderr, "Socket failed");
return EXIT_FAILURE;
}
if ((connect(sock2, (struct sockaddr *) servinfo->ai_addr, servinfo->ai_addrlen)) != 0)
{
fprintf(stderr, "Connection failed");
return EXIT_FAILURE;
}
while (1) {
//char msg[BUF_SIZE] = "ashudfshuhafhu";
//char msg[BUF_SIZE];
//fgets(msg, BUF_SIZE, stdin);
//int i = 2;
//if (strlen(msg) == i)
// break;
int bytes_received;
// fprintf(stdout, "Sending %s", msg);
//send(sock, msg , strlen(msg), 0);
if((bytes_received = recv(sock, buf, BUF_SIZE, 0)) > 1)
{
buf[bytes_received] = '\0';
fprintf(stdout, "Received %s", buf);
}
}
freeaddrinfo(servinfo);
close(sock);
return EXIT_SUCCESS;
}
Server.c
#include <netinet/in.h>
#include <netinet/ip.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
#define ECHO_PORT 9999
#define BUF_SIZE 4096
int close_socket(int sock)
{
if (close(sock))
{
fprintf(stderr, "Failed closing socket.\n");
return 1;
}
return 0;
}
int main(int argc, char* argv[])
{
int sock, client_sock;
ssize_t readret;
socklen_t cli_size;
struct timeval tv;
struct sockaddr_in addr, cli_addr;
char buf[BUF_SIZE] = "wetwetwetwetwetwetwetwet";
fd_set readfds, writefds;
fd_set activereadfds, activewritefds;
cli_size = sizeof(&cli_addr);
tv.tv_sec = 5;
tv.tv_usec = 0;
fprintf(stdout, "----- Echo Server -----\n");
/* all networked programs must create a socket */
if ((sock = socket(PF_INET, SOCK_STREAM, 0)) == -1)
{
fprintf(stderr, "Failed creating socket.\n");
return EXIT_FAILURE;
}
addr.sin_family = AF_INET;
addr.sin_port = htons(ECHO_PORT);
addr.sin_addr.s_addr = INADDR_ANY;
/* servers bind sockets to ports---notify the OS they accept connections */
if (bind(sock, (struct sockaddr *) &addr, sizeof(addr)))
{
close_socket(sock);
fprintf(stderr, "Failed binding socket.\n");
return EXIT_FAILURE;
}
if (listen(sock, 5))
{
close_socket(sock);
fprintf(stderr, "Error listening on socket.\n");
return EXIT_FAILURE;
}
FD_ZERO(&readfds);
FD_SET(sock, &activereadfds);
while (1)
{
fprintf(stdout,"in here.\n");
readfds = activereadfds;
writefds = activewritefds;
FD_ZERO(&activereadfds);
FD_ZERO(&activewritefds);
if (select(51, &readfds, &writefds, NULL, &tv) < 0)
{
perror("select");
return EXIT_FAILURE;
}
for (int i = 0; i < 10; ++i)
{
if (FD_ISSET (i, &readfds))
{
if (i == sock)
{
fprintf(stdout, "main loop. \n");
client_sock = accept(sock,
(struct sockaddr *) &cli_addr, &cli_size);
FD_SET(client_sock, &activereadfds);
FD_SET(client_sock, &activewritefds);
if (client_sock < 0)
{
perror("accept");
return EXIT_FAILURE;
}
} else {
fprintf(stdout, "second loop \n");
readret = send(i,buf, strlen(buf),0);
if (readret < 0)
fprintf(stdout, "yay");
}
}
if (FD_ISSET(i, &writefds))
{ fprintf(stdout, "ugh \n");
readret = send(i,buf,BUF_SIZE,0);
//if (readret > 0)
//while((readret = recv(i, buf, BUF_SIZE, 0)) >= 1)
// {
//if (send(i, buf, readret, 0) != readret)
//{
// close_socket(i);
// close_socket(sock);
// fprintf(stderr, "Error sending to client.\n");
// return EXIT_FAILURE;
//}
}
}
}
close_socket(sock);
return EXIT_SUCCESS;
}
您的服务器发送仅当插槽中安装阅读,并作为客户端是永远发送,服务器也不是。服务器发送应在客户端套接字在
writefds
中启动时发生,但实际上这不是使用该功能的正确方式。真的,你应该只发送,并且只有加入并担心writefds
如果send()
导致EAGAIN/EWOULDBLOCK。-
你可以在客户端得到一个未被发现的错误:
if((bytes_received = recv(sock, buf, BUF_SIZE, 0)) > 1) { buf[bytes_received] = '\0'; fprintf(stdout, "Received %s", buf); }
这应该继续:
else if (bytes_received == 0) { fprintf(stdout, "peer disconnected\n"); break; } else // < 0: error { fprintf(stdout, "recv() error %s\n", strerror(errno)); break; }
你需要,只要你从得到一个错误打印这样实际的错误系统调用。
为什么客户端必须发送服务器发送? –
我已经在第一段中正确解释了这一点。 – EJP
对于误解我表示抱歉,但我想知道服务器如何知道什么时候发送到套接字,特别是如何以我现在拥有它的方式将'socketfid'添加到'writefds'不是一种好的做法。 –
调试器告诉你什么当你通过代码? (当你阅读它时,你的客户端代码对你有多大的意义) –
当我阅读它时,代码对我来说是有意义的,但那可能是因为我是套接字编程的新手。 –