C套接字编程:recv总是失败
我正在为大学考试学习C套接字编程。 我举了一个简单的例子: socket_server.cC套接字编程:recv总是失败,c,sockets,C,Sockets,我正在为大学考试学习C套接字编程。 我举了一个简单的例子: socket_server.c #include <sys/socket.h> #include <stdio.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <arpa/inet.h> #define SA struct sockaddr #define MAX
#include <sys/socket.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <arpa/inet.h>
#define SA struct sockaddr
#define MAX_MESS_LEN 16
int main(){
struct sockaddr_in my_addr, cl_addr;
int ret, len, sk, cn_sk;
char cl_ip[INET_ADDRSTRLEN + 1], msg[MAX_MESS_LEN + 1];
sk = socket(AF_INET, SOCK_STREAM, 0); //creo socket TCP/IPv4 listener
printf("socket created! :)\n");
memset(&my_addr, 0, sizeof(my_addr)); //azzero struttura my_addr
my_addr.sin_family = AF_INET; //famiglia protocolli IPv4
my_addr.sin_addr.s_addr = htonl(INADDR_ANY); //in ascolto su qualsiasi interfaccia
my_addr.sin_port = htons(1234); //porta del socket
ret = bind(sk, (SA *) &my_addr, sizeof(my_addr)); //lego il socket alla struttura indirizzo
printf("socket binded! :)\n");
ret = listen(sk, 10); //mi pongo in ascolto sul socket con massimo 10 richieste pendenti
printf("socket listening (on any interface with port 1234)! :)\n");
len = sizeof(cl_addr);
printf("socket is going to wait for a request... zzzzZZZ\n");
cn_sk = accept(sk, (SA *) &cl_addr, &len); //creo il socket connected per la richiesta in cima alla lista
printf("socket accepted request! :D\n");
inet_ntop(AF_INET, &cl_addr.sin_addr, cl_ip, INET_ADDRSTRLEN); //converto indirizzo IPv4 cl_addr.sin_addr in stringa (cl_ip)
printf("IP client: %s\n", cl_ip);
ret = recv(sk, (void *) msg, MAX_MESS_LEN, MSG_WAITALL); //attendo la ricezione di tutti i caratteri della stringa inviata sul socket dal client
msg[MAX_MESS_LEN + 1] = '\0';
printf("received data (%d bytes): %s\n", ret, msg);
if(ret == -1 || ret < MAX_MESS_LEN)
printf("recv ERROR! :(\n");
close(sk); //chiudo il server
}
也许这是一个愚蠢的问题,但服务器中的recv功能总是失败,下面是一个示例输出:
服务器:
socket created! :)
socket binded! :)
socket listening (on any interface with port 1234)! :)
socket is going to wait for a request... zzzzZZZ
socket accepted request! :D
IP client: 192.168.1.132
received data (-1 bytes): ����
recv ERROR! :(
客户:
Socket created! :)
Trying to establish a connection with 192.168.1.132 on port 1234...Connection established! :D
sending message: something to send
有什么问题吗?我不明白(我一步一步地跟着老师走
我运行的是arch linux 64位;)
谢谢您的回复
cn_sk = accept(sk, (SA *) &cl_addr, &len); //creo il socket connected per la richiesta in cima alla lista
...
ret = recv(sk, (void *) msg, MAX_MESS_LEN, MSG_WAITALL); //at
您不需要在连接到客户端的套接字上recv
,而是在侦听器套接字上sk
。如果您检查errno
,您可能会看到ENOTCONN
您不需要在连接到客户端的套接字上
recv
,而是在侦听器套接字上sk
。如果您检查errno
,您可能会看到ENOTCONN
在错误上使用perror
而不是printf
(或者以某种方式显示errno
和strerror(errno)
)。另外,使用所有警告和调试信息进行编译(gcc-Wall-g
)。然后使用调试器(gdb
)。仔细阅读的文档。在错误上使用perror
而不是printf
(或以某种方式显示errno
和strerror(errno)
)。另外,使用所有警告和调试信息进行编译(gcc-Wall-g
)。然后使用调试器(gdb
)。请仔细阅读的文档。谢谢!我不相信我为这样一个愚蠢的错误发布了一个问题,对不起:谢谢!我不相信我为这样一个愚蠢的错误发布了一个问题,对不起:P
Socket created! :)
Trying to establish a connection with 192.168.1.132 on port 1234...Connection established! :D
sending message: something to send
cn_sk = accept(sk, (SA *) &cl_addr, &len); //creo il socket connected per la richiesta in cima alla lista
...
ret = recv(sk, (void *) msg, MAX_MESS_LEN, MSG_WAITALL); //at