[mdns] Fix select issue on FreeBSD.

As reported in issue #1654, using select to test for a (non-blocking) connection success crashes on FreeBSD when the number of opened file descriptor is higher than FDSET_SIZE.
Instead of returning with an error in that case, this commit uses poll instead that's not limited to the number of opened file descriptors, preventing an out-of-bound write.
This commit is contained in:
X-Ryl669 2023-09-29 17:33:23 +02:00
parent 8528073003
commit ab790c2880
1 changed files with 7 additions and 6 deletions

View File

@ -36,6 +36,7 @@
#include <net/if.h>
#include <unistd.h>
#include <fcntl.h>
#include <poll.h>
#include <event2/event.h>
@ -582,8 +583,7 @@ connection_test(int family, const char *address, const char *address_log, int po
struct addrinfo *ai;
char strport[32];
int sock;
fd_set fdset;
struct timeval timeout = { MDNS_CONNECT_TEST_TIMEOUT, 0 };
struct pollfd fd;
socklen_t len;
int flags;
int error;
@ -639,10 +639,11 @@ connection_test(int family, const char *address, const char *address_log, int po
// the case, but FreeBSD connect() sometimes returns immediate success.
if (ret != 0)
{
FD_ZERO(&fdset);
FD_SET(sock, &fdset);
ret = select(sock + 1, NULL, &fdset, NULL, &timeout);
// Use poll here since select requires using fdset that would be overflowed in FreeBSD
fd.fd = sock;
fd.events = POLLOUT;
ret = poll(&fd, 1, MDNS_CONNECT_TEST_TIMEOUT * 1000);
if (ret < 0)
{
DPRINTF(E_WARN, L_MDNS, "Connection test to %s:%d failed with select error: %s\n", address_log, port, strerror(errno));