let ping6 set the IPv6 traffic class like it does for IPv4 TOS

[David Gwynne]

This sets ping6 up to specify the traffic class field for the IPv6
traffic class field. The v6 traffic class is equivalent to the IPv6
TOS/DSCP field, so this uses the same getopt param and parsing to get
the value.

ok?

Index: ping.8
===================================================================
RCS file: /cvs/src/sbin/ping/ping.8,v
retrieving revision 1.59
diff -u -p -r1.59 ping.8
--- ping.8      26 Oct 2016 16:18:45 -0000      1.59
+++ ping.8      9 Nov 2018 05:05:35 -0000
@@ -87,6 +87,7 @@
 .Op Fl l Ar preload
 .Op Fl p Ar pattern
 .Op Fl s Ar packetsize
+.Op Fl T Ar toskeyword
 .Op Fl V Ar rtable
 .Op Fl w Ar maxwait
 .Ar host
@@ -221,8 +222,7 @@ which translates into 64 ICMP data bytes
 when combined with the 8 bytes of ICMP header data.
 The maximum packet size is 65467 for IPv4 and 65527 for IPv6.
 .It Fl T Ar toskeyword
-.Pq IPv4 only
-Change the TOS value.
+Change the IPv4 TOS or IPv6 Traffic Class value.
 .Ar toskeyword
 may be one of
 .Cm critical ,
Index: ping.c
===================================================================
RCS file: /cvs/src/sbin/ping/ping.c,v
retrieving revision 1.230
diff -u -p -r1.230 ping.c
--- ping.c      14 Oct 2018 19:47:53 -0000      1.230
+++ ping.c      9 Nov 2018 05:05:35 -0000
@@ -150,7 +150,7 @@ int options;
 /*                     0x0200 */
 #define        F_HDRINCL       0x0400
 #define        F_TTL           0x0800
-/*                     0x1000 */
+#define        F_TOS           0x1000
 #define        F_AUD_RECV      0x2000
 #define        F_AUD_MISS      0x4000
 
@@ -291,7 +291,7 @@ main(int argc, char *argv[])
        preload = 0;
        datap = &outpack[ECHOLEN + ECHOTMLEN];
        while ((ch = getopt(argc, argv, v6flag ?
-           "c:dEefHh:I:i:Ll:mNnp:qS:s:V:vw:" :
+           "c:dEefHh:I:i:Ll:mNnp:qS:s:T:V:vw:" :
            "DEI:LRS:c:defHi:l:np:qs:T:t:V:vw:")) != -1) {
                switch(ch) {
                case 'c':
@@ -386,6 +386,7 @@ main(int argc, char *argv[])
 #ifndef SMALL
                case 'T':
                        options |= F_HDRINCL;
+                       options |= F_TOS;
                        errno = 0;
                        errstr = NULL;
                        if (map_tos(optarg, &tos))
@@ -671,6 +672,13 @@ main(int argc, char *argv[])
                        scmsg->cmsg_level = IPPROTO_IPV6;
                        scmsg->cmsg_type = IPV6_HOPLIMIT;
                        *(int *)(CMSG_DATA(scmsg)) = hoplimit;
+               }
+
+               if (options & F_TOS) {
+                       optval = tos;
+                       if (setsockopt(s, IPPROTO_IPV6, IPV6_TCLASS, &optval,
+                           (socklen_t)sizeof(optval)) < 0)
+                               warn("setsockopt(IPV6_TVAL)"); /* XXX err? */
                }
 
                optval = 1;