check_dhcp: Make xid a bit more random

Don't just use the current time(2) to seed the PRNG that generates the
xid.  A DHCP server might be checked multiple times per second.

1 files changed, 2 insertions, 3 deletions

diff --git a/plugins-root/check_dhcp.c b/plugins-root/check_dhcp.c
index 445ddbc1..88b7ca10 100644
--- a/plugins-root/check_dhcp.c
+++ b/plugins-root/check_dhcp.c
@@ -463,10 +463,9 @@ int send_dhcp_discover(int sock){
         discover_packet.hlen=ETHERNET_HARDWARE_ADDRESS_LENGTH;
 
         /*
-         * transaction ID is supposed to be random.  We won't use the address so
-         * we don't care about high entropy here.  time(2) is good enough.
+         * transaction ID is supposed to be random.
          */
-        srand(time(NULL));
+        srand(time(NULL)^getpid());
         packet_xid=random();
         discover_packet.xid=htonl(packet_xid);