Due to the complexity of this situation I have to reproduce this is the
smallest program I could write that produces "connect: cannot assign
requested address". The first run on my machine, it counts to ~220 and then
fails with errno 99 on all of the client processes. It then fails
immediately if I run it again, but if you wait you'll have to run it again.
Sometimes it fails with "bind: Address already in use" followed by
"connect: Connection refused" from all of the clients; this happens
non-deterministically. Please don't judge this program too harshly because
it serves only to get connect to give that errno. It requires netstat,
which is in package net-tools. The program is below as well as attached.
#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
const int PORTNUM = 2423;
const int BACKLOG = 128;
int in_socketfd;
void handle(int interrupt) {
sched_yield();
close(in_socketfd);
exit(0);
}
void server() {
// on SIGINT, exit cleanly
struct sigaction term_act;
term_act.sa_handler = handle;
sigemptyset(&term_act.sa_mask);
term_act.sa_flags = 0;
if (sigaction(SIGINT, &term_act, NULL)) {
perror("sigaction");
exit(errno);
}
in_socketfd = socket(AF_INET, SOCK_STREAM, 0);
if (in_socketfd == -1) {
perror("socket");
exit(errno);
}
struct sockaddr_in in_addr;
memset(&in_addr,0,sizeof(in_addr));
in_addr.sin_family = AF_INET;
in_addr.sin_addr.s_addr = htonl(INADDR_ANY);
in_addr.sin_port = htons(PORTNUM);
if (bind(in_socketfd, (struct sockaddr*)&in_addr,
sizeof(struct sockaddr_in))) {
perror("bind");
exit(errno);
};
if (listen(in_socketfd,BACKLOG)) {
perror("listen");
exit(errno);
}
while (1) {
struct sockaddr_in dest;
socklen_t dest_size = sizeof(struct sockaddr_in);
int socketfd = accept(in_socketfd, (struct sockaddr*) &dest,
&dest_size);
if (socketfd == -1) {
perror("accept");
exit(errno);
}
char placeholder[15];
assert(recv(socketfd, placeholder, 15, 0) == 0);
// close(socketfd);
}
}
int client() {
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
perror("socket");
return errno;
}
struct sockaddr_in dest;
memset(&dest,0,sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
dest.sin_port = htons(PORTNUM);
if (connect(sockfd,(struct sockaddr*)&dest,
sizeof(struct sockaddr_in)) == -1) {
perror("connect");
return errno;
}
close(sockfd);
return EXIT_SUCCESS;
}
#define fork_split() \
do { \
pid_t pid = fork();
#define fork_join() \
if (pid) { \
int child_ret; \
waitpid(pid, &child_ret, 0); \
ret = ret || child_ret; \
} else { \
exit(ret); \
} \
} while (0);
int test() {
int ret = EXIT_SUCCESS;
int spid = fork();
if (spid) {
// parent : clients
// wait for server to be listening
while (WEXITSTATUS(system("netstat -tapen 2>/dev/null | grep
':2423' >/dev/null")) == 1) {
sched_yield();
}
fork_split();
fork_split();
fork_split();
fork_split();
fork_split();
fork_split();
fork_split();
ret = client();
fork_join();
fork_join();
fork_join();
fork_join();
fork_join();
fork_join();
fork_join();
kill(spid, SIGINT);
int s_ret;
waitpid(spid, &s_ret,0);
return s_ret || ret;
} else {
// child : server
server();
}
return ret;
}
int main() {
int i = 0;
while (test() == EXIT_SUCCESS) {
printf("%i\n",i++);
}
}
On Fri, Apr 25, 2014 at 8:43 AM, Michael Kerrisk (man-pages) <
mtk.manpa...@gmail.com> wrote:
> William, this report is a little vague... Do you have a *minimal*
> program that demonstrates the problem?
>
#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
const int PORTNUM = 2423;
const int BACKLOG = 128;
int in_socketfd;
void handle(int interrupt) {
sched_yield();
close(in_socketfd);
exit(0);
}
void server() {
// on SIGINT, exit cleanly
struct sigaction term_act;
term_act.sa_handler = handle;
sigemptyset(&term_act.sa_mask);
term_act.sa_flags = 0;
if (sigaction(SIGINT, &term_act, NULL)) {
perror("sigaction");
exit(errno);
}
in_socketfd = socket(AF_INET, SOCK_STREAM, 0);
if (in_socketfd == -1) {
perror("socket");
exit(errno);
}
struct sockaddr_in in_addr;
memset(&in_addr,0,sizeof(in_addr));
in_addr.sin_family = AF_INET;
in_addr.sin_addr.s_addr = htonl(INADDR_ANY);
in_addr.sin_port = htons(PORTNUM);
if (bind(in_socketfd, (struct sockaddr*)&in_addr,
sizeof(struct sockaddr_in))) {
perror("bind");
exit(errno);
};
if (listen(in_socketfd,BACKLOG)) {
perror("listen");
exit(errno);
}
while (1) {
struct sockaddr_in dest;
socklen_t dest_size = sizeof(struct sockaddr_in);
int socketfd = accept(in_socketfd, (struct sockaddr*) &dest,
&dest_size);
if (socketfd == -1) {
perror("accept");
exit(errno);
}
char placeholder[15];
assert(recv(socketfd, placeholder, 15, 0) == 0);
// close(socketfd);
}
}
int client() {
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
perror("socket");
return errno;
}
struct sockaddr_in dest;
memset(&dest,0,sizeof(dest));
dest.sin_family = AF_INET;
dest.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
dest.sin_port = htons(PORTNUM);
if (connect(sockfd,(struct sockaddr*)&dest,
sizeof(struct sockaddr_in)) == -1) {
perror("connect");
return errno;
}
close(sockfd);
return EXIT_SUCCESS;
}
#define fork_split() \
do { \
pid_t pid = fork();
#define fork_join() \
if (pid) { \
int child_ret; \
waitpid(pid, &child_ret, 0); \
ret = ret || child_ret; \
} else { \
exit(ret); \
} \
} while (0);
int test() {
int ret = EXIT_SUCCESS;
int spid = fork();
if (spid) {
// parent : clients
// wait for server to be listening
while (WEXITSTATUS(system("netstat -tapen 2>/dev/null | grep ':2423' >/dev/null")) == 1) {
sched_yield();
}
fork_split();
fork_split();
fork_split();
fork_split();
fork_split();
fork_split();
fork_split();
ret = client();
fork_join();
fork_join();
fork_join();
fork_join();
fork_join();
fork_join();
fork_join();
kill(spid, SIGINT);
int s_ret;
waitpid(spid, &s_ret,0);
return s_ret || ret;
} else {
// child : server
server();
}
return ret;
}
int main() {
int i = 0;
while (test() == EXIT_SUCCESS) {
printf("%i\n",i++);
}
}
