NFS: Add a minimum support for NFSv4

tcpdump does not support NFSv4 and prints out wrong NFS data which
always be "getattr" for NFSv4, because both NFSv4 COMPOUND procedure
and NFSv2/3 GETATTR procedure are the same value '1'.

This is a minimum support for NFSv4, which detects NFSv4 and can print
out NULL procedure or COMPOUND procedure at least.

Log of current no-NFSv4 support:
  NFS4_OK case
    18:03:38.718964 IP client.815 > server.nfs: Flags [P.], seq 192:312, ack 177, win 22430, options [nop,nop,TS val 2190058497 ecr 3789310763], length 120: NFS request xid 1660218411 116 getattr fh 0,1/53
    18:03:38.719279 IP server.nfs > client.815: Flags [P.], seq 177:261, ack 312, win 3333, options [nop,nop,TS val 3789310764 ecr 2190058497], length 84: NFS reply xid 1660218411 reply ok 80 getattr NON 1 ids 0/159 sz -719751424
  NFS4ERR_NOENT case
    18:03:44.707900 IP client.815 > server.nfs: Flags [P.], seq 312:512, ack 261, win 22430, options [nop,nop,TS val 2190064486 ecr 3789310864], length 200: NFS request xid 1676995627 196 getattr fh 0,1/53
    18:03:44.708575 IP server.nfs > client.815: Flags [P.], seq 261:361, ack 512, win 3333, options [nop,nop,TS val 3789316753 ecr 2190064486], length 100: NFS reply xid 1676995627 reply ok 96 getattr ERROR: No such file or directory

Log of this minimum NFSv4 support:
  NFS4_OK case
    18:06:18.975026 IP client.815 > server.nfs: Flags [P.], seq 488:608, ack 549, win 22430, options [nop,nop,TS val 2190218753 ecr 3789464067], length 120: NFS request xid 1861545003 116 v4 compound
    18:06:18.975276 IP server.nfs > client.815: Flags [P.], seq 549:633, ack 608, win 3333, options [nop,nop,TS val 3789471020 ecr 2190218753], length 84: NFS reply xid 1861545003 reply ok 80 v4 compound
  NFS4ERR_NOENT case
    17:51:08.684565 IP client.815 > server.nfs: Flags [P.], seq 432:632, ack 345, win 22430, options [nop,nop,TS val 2189308462 ecr 3788560729], length 200: NFS request xid 888466475 196 v4 compound
    17:51:08.685081 IP server.nfs > client.815: Flags [P.], seq 345:445, ack 632, win 3333, options [nop,nop,TS val 3788560730 ecr 2189308462], length 100: NFS reply xid 888466475 reply ok 96 v4 compound ERROR: No such file or directory

Signed-off-by: Seiichi Ikarashi <s.ikarashi@fujitsu.com>

Author: sikarash

nfs.h

@@ -53,6 +53,7 @@
 #define	NFS_PROG	100003
 #define NFS_VER2	2
 #define	NFS_VER3	3
+#define	NFS_VER4	4
 #define NFS_V2MAXDATA	8192
 #define	NFS_MAXDGRAMDATA 16384
 #define	NFS_MAXDATA	32768

print-nfs.c

@@ -571,6 +571,19 @@ nfsreq_noaddr_print(netdissect_options *ndo,
 	v3 = (GET_BE_U_4(&rp->rm_call.cb_vers) == NFS_VER3);
 	proc = GET_BE_U_4(&rp->rm_call.cb_proc);
 
+	if (GET_BE_U_4(&rp->rm_call.cb_vers) == NFS_VER4) {
+		ND_PRINT(" v4");
+		switch (proc) {
+			case 0:
+				ND_PRINT(" null");
+				break;
+			case 1:
+				ND_PRINT(" compound");
+				break;
+		}
+		return;
+	}
+
 	if (!v3 && proc < NFS_NPROCS)
 		proc =  nfsv3_procid[proc];
 
@@ -1539,6 +1552,25 @@ interp_reply(netdissect_options *ndo,
 	u_int er;
 	int nfserr = 0;
 
+	if (vers == NFS_VER4) {
+		ND_PRINT(" v4");
+		switch (proc) {
+			case 0:
+				ND_PRINT(" null");
+				break;
+			case 1:
+				ND_PRINT(" compound");
+				break;
+		}
+		dp = parserep(ndo, rp, length, &nfserr);
+		if (dp == NULL)
+			goto trunc;
+		dp = parsestatus(ndo, dp, &er, &nfserr);
+		if (dp == NULL)
+			goto trunc;
+		return;
+	}
+
 	v3 = (vers == NFS_VER3);
 
 	if (!v3 && proc < NFS_NPROCS)