Get rid of the RANDOM_IP_ID option and make it a sysctl. NetBSD

have already done this, so I have styled the patch on their work:

        1) introduce a ip_newid() static inline function that checks
        the sysctl and then decides if it should return a sequential
        or random IP ID.

        2) named the sysctl net.inet.ip.random_id

        3) IPv6 flow IDs and fragment IDs are now always random.
        Flow IDs and frag IDs are significantly less common in the
        IPv6 world (ie. rarely generated per-packet), so there should
        be smaller performance concerns.

The sysctl defaults to 0 (sequential IP IDs).

Reviewed by:	andre, silby, mlaier, ume
Based on:	NetBSD
MFC after:	2 months

1 files changed, 0 insertions, 5 deletions

diff --git a/sys/netinet/tcp_syncache.c b/sys/netinet/tcp_syncache.c
index 6ceff8f..9c918a9 100644
--- a/sys/netinet/tcp_syncache.c
+++ b/sys/netinet/tcp_syncache.c
@@ -38,7 +38,6 @@
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
 #include "opt_mac.h"
-#include "opt_random_ip_id.h"
 #include "opt_tcpdebug.h"
 #include "opt_tcp_sack.h"
 
@@ -958,11 +957,7 @@ syncache_add(inc, to, th, sop, m)
 		if (inc->inc_isipv6 &&
 		    (sc->sc_tp->t_inpcb->in6p_flags & IN6P_AUTOFLOWLABEL)) {
 			sc->sc_flowlabel =
-#ifdef RANDOM_IP_ID
 			    (htonl(ip6_randomflowlabel()) & IPV6_FLOWLABEL_MASK);
-#else
-			    (htonl(ip6_flow_seq++) & IPV6_FLOWLABEL_MASK);
-#endif
 		}
 #endif
 	}