Merge pull request #4476 from minus7/master

Fix hanging arp_check

1 files changed, 10 insertions, 4 deletions

diff --git a/src/firejail/arp.c b/src/firejail/arp.c
index bbab9a6d9..c259fc0ad 100644
--- a/src/firejail/arp.c
+++ b/src/firejail/arp.c
@@ -20,6 +20,7 @@
 #include "firejail.h"
 #include <sys/socket.h>
 #include <sys/ioctl.h>
+#include <sys/time.h>
 #include <linux/if_ether.h>                       //TCP/IP Protocol Suite for Linux
 #include <net/if.h>
 #include <netinet/in.h>
@@ -188,9 +189,14 @@ int arp_check(const char *dev, uint32_t destaddr) {
         FD_SET(sock, &fds);
         int maxfd = sock;
         struct timeval ts;
-        ts.tv_sec = 0; // 0.5 seconds wait time
-        ts.tv_usec = 500000;
+        gettimeofday(&ts, NULL);
+        double timerend = ts.tv_sec + ts.tv_usec / 1000000.0 + 0.5;
         while (1) {
+                gettimeofday(&ts, NULL);
+                double now = ts.tv_sec + ts.tv_usec / 1000000.0;
+                double timeout = timerend - now;
+                ts.tv_sec = timeout;
+                ts.tv_usec = (timeout - ts.tv_sec) * 1000000;
                 int nready = select(maxfd + 1,  &fds, (fd_set *) 0, (fd_set *) 0, &ts);
                 if (nready < 0)
                         errExit("select");
@@ -201,8 +207,8 @@ int arp_check(const char *dev, uint32_t destaddr) {
                         }
                         if (sendto (sock, frame, 14 + sizeof(ArpHdr), 0, (struct sockaddr *) &addr, sizeof (addr)) <= 0)
                                 errExit("send");
-                        ts.tv_sec = 0; // 0.5 seconds wait time
-                        ts.tv_usec = 500000;
+                        gettimeofday(&ts, NULL);
+                        timerend = ts.tv_sec + ts.tv_usec / 1000000.0 + 0.5;
                         fflush(0);
                 }
                 else {