关于C#：Socket编程：接收/读取问题

Socket programming: recv/read issue

编辑：下面的代码已修复，可以正确接收和发送，并且考虑到已发送和接收到的消息的实际字节数(这要归功于EJP)

我正在Unix中使用C编程。

我有应该交换消息的服务器和客户端。虽然客户端似乎可以很好地发送消息，但是服务器没有收到客户端正在发送的消息。我试过使用recv()和read()(我知道它们实际上是同一件事，但是在recv()上带有额外的标志)，但是我没有运气，而且我不确定问题的根源。

每次发送消息后，我都会在客户端代码中放入sleep(3)，但是我看到，一旦客户端和服务器连接，服务器将立即关闭，而无需等待传入的消息。我在做什么错？

这是客户端代码：

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#define SERVER_TCP_PORT 11112
#define MAX_DATA_SIZE 500

int main(int argc, char * argv[])
{
int sockfd;
char * host;
char msg[MAX_DATA_SIZE];/* ="get my msg!\
";*/
int msg_len;

struct hostent * hp;
struct sockaddr_in client_address, server_address;

printf("y halo thar\
");

// looking up from the host database
if (argc == 2)
host = argv[1];
else
exit(1);
printf("sdf\
");

hp = gethostbyname(host);
if (!hp)
exit(1);
printf("host found\
");

// setting up address and port structure information
bzero((char * ) &server_address, sizeof(server_address)); // copy zeroes into string
server_address.sin_family = AF_INET;
bcopy(hp->h_addr, (char *) &server_address.sin_addr, hp->h_length);
server_address.sin_port = htons(SERVER_TCP_PORT);
printf("set\
");

// opening up socket
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
exit(1);
printf("opened\
");

// connecting
if (connect(sockfd, (struct sockaddr *) &server_address, sizeof(server_address)) < 0)
exit(1);
printf("connected\
");

int i;

for (i = 0; i < MAX_DATA_SIZE; ++i)
{
msg[i] = '.';
}

msg[MAX_DATA_SIZE-1] = '\\0';

for(i = 0; i < 11; i++)
{
// send message to connected socket
msg_len = write(sockfd, msg, MAX_DATA_SIZE);
if(msg_len < 1)
printf("notsent\
");
else
printf("%i bytes sent\
", msg_len);

// recieve messages from connected socket
msg_len = read(sockfd, msg, MAX_DATA_SIZE);
if (msg_len < 1)
printf("not recieved\
");
else
{
printf("%i bytes received\
", msg_len);
printf(msg);
printf("\
");

}
}

// close connection
close(sockfd);
printf("closed\
");

}

这是服务器端

#define SERVER_TCP_PORT 11112
#define MAX_DATA_SIZE 500

int main()
{

printf("o halo thar\
");

int sockfd, new_sockfd;
int client_addr_len;
char msg [MAX_DATA_SIZE];
int msg_len;
char got_msg [11] ="got ur msg\\0";
struct sockaddr_in server_address, client_address;

// setting up address and port structure information
bzero((char * ) &server_address, sizeof(server_address)); // copy zeroes into string
server_address.sin_family = AF_INET;
server_address.sin_addr.s_addr = htonl(INADDR_ANY);
server_address.sin_port = htons(SERVER_TCP_PORT);

// opening up socket
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
exit(1);
printf("socket is opened\
");

// binding
if (bind(sockfd, (struct sockaddr *) &server_address, sizeof(server_address)) < 0)
exit(1);
printf("socket is bound\
");

// listening
listen(sockfd,5);
printf("listening\
");

// block and wait for an incoming connection

client_addr_len = sizeof(client_address);
new_sockfd = accept(sockfd, (struct sockaddr *) &client_address, &client_addr_len);
if (new_sockfd < 0)
exit(1);

printf("accepted\
");

int i;

for( i = 0; i < 11; i++)
{
// recieve messages from connected socket
printf("waiting\
");
msg_len = read(new_sockfd, msg, MAX_DATA_SIZE);
if (msg_len < 1)
{
printf("no msg recieved\
");
}
else
{
printf("bytes recieved: %i\
", msg_len);
}

// send message to connected socket
msg_len = write(new_sockfd, got_msg, sizeof(got_msg));
if (msg_len < 1)
printf("not sent\
");
else
printf("%i bytes sent\
", msg_len);
}

// close connection
close(sockfd);
printf("socket closed. BYE! \
");

}

在服务器代码中，问题出在以下一行：

1	msg_len = read(sockfd, msg, MAX_DATA_SIZE);

您正在sockfd上调用read，但是您需要在new_sockfd(accept()返回的套接字)上调用read或recv。 new_sockfd是连接到客户端的一个(sockfd用于接受其他连接-例如，如果另一个客户端连接)。