Reputation: 7990
I've already read about how to prevent SIGPIPE
, then I write a small program to test it. Here is the code.
server.c
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
void hdl(int sig_num, siginfo_t *sig_info, void *context)
{
printf("got you, SIGPIPE!\n");
}
int main()
{
int sfd, cfd;
struct sockaddr_in saddr, caddr;
struct sigaction act;
memset (&act, '\0', sizeof(act));
act.sa_sigaction = hdl;
act.sa_flags = SA_SIGINFO;
if (sigaction(SIGPIPE, &act, NULL) < 0) {
return 1;
}
sfd= socket(AF_INET, SOCK_STREAM, 0);
saddr.sin_family=AF_INET;
saddr.sin_addr.s_addr=inet_addr("192.168.22.91");
saddr.sin_port=htons(12345);
if(bind(sfd, (struct sockaddr *)&saddr, sizeof(saddr)) )
{
printf("bind error\n");
return -1;
}
if(listen(sfd, 1))
{
printf("error\n");
return -1;
}
char buf[1024] = {0};
while(1) {
printf("Server listening...\n");
cfd=accept(sfd, (struct sockaddr *)NULL, NULL);
fcntl(cfd, F_SETFL, O_NONBLOCK);
int size = read(cfd, buf, 1024);
if(size == -1)
printf("read error\n");
sleep(2); // sleep for a while to make sure the client closed the socket
int ret;
if((ret = write(cfd, buf, strlen(buf)))<0)
{
if(errno == EPIPE)
fprintf(stderr, "SIGPIPE");
}
ret = write(cfd, buf, strlen(buf)); // write again.
printf("write return %d\n", ret);
}
close(sfd);
}
client.c
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <assert.h>
int main()
{
int ret, fd;
struct sockaddr_in sa_dst;
char buffer[] = "hello, world";
char rcv_buf[128] = {0};
fd = socket(AF_INET, SOCK_STREAM, 0);
memset(&sa_dst, 0, sizeof(struct sockaddr_in));
sa_dst.sin_family = AF_INET;
sa_dst.sin_port = htons(12345);
sa_dst.sin_addr.s_addr = inet_addr("192.168.22.91");
ret = connect(fd, (struct sockaddr *)&sa_dst, sizeof(struct sockaddr));
if(ret != -1)
{
send(fd, buffer, strlen(buffer), 0);
close(fd);
}
return 0;
}
When I run the server and the client on the same linux machine, on the server side, the first write()
returns the number of bytes written while I expect a SIGPIPE
signal because I closed the socket on the client side, the second write()
does generate a SIGPIPE
signal.
But when I ran the client on another linux machine or on a Windows machine(implement the same client with Winsock), I did't catch any SIGPIPE
signal, and the second write()
still returns the size of the buffer
. Can someone tell me what's going on?
Upvotes: 1
Views: 1339
Reputation: 226
Just Change this in SERVER and it will work
fcntl(cfd, F_SETFL, O_NONBLOCK);
int size = read(cfd, buf, 1024);
if(size == -1)
printf("read error\n");
sleep(2); // sleep for a while to make sure the client closed the socket
int ret;
ret = write(cfd, buf, strlen(buf));
sleep(2);
ret = write(cfd, buf, strlen(buf)); // write again.
printf("write return %d\n", ret);
Upvotes: 0
Reputation: 310903
It can't happen on the first write, for two reasons:
NB you're corrupting the value of errno
by calling perror(),
so testing it afterwards isn't valid.
Upvotes: 1