Introduce MTU option.

The MTU option is used in Router Advertisement messages to ensure that
all nodes on a link use the same MTU value in those cases where the link
MTU is not well known.

Feedback (thank you!) and OK from florian@

diff --git a/usr.sbin/rad/frontend.c b/usr.sbin/rad/frontend.c
index b06fa43..d44701d 100644 (file)
--- a/usr.sbin/rad/frontend.c
+++ b/usr.sbin/rad/frontend.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: frontend.c,v 1.11 2018/07/18 09:10:50 florian Exp $   */
+/*     $OpenBSD: frontend.c,v 1.12 2018/07/20 17:55:09 bket Exp $      */
 
 /*
  * Copyright (c) 2018 Florian Obser <florian@openbsd.org>
@@ -887,6 +887,7 @@ void
 build_packet(struct ra_iface *ra_iface)
 {
        struct nd_router_advert         *ra;
+       struct nd_opt_mtu               *ndopt_mtu;
        struct nd_opt_prefix_info       *ndopt_pi;
        struct ra_iface_conf            *ra_iface_conf;
        struct ra_options_conf          *ra_options_conf;
@@ -904,6 +905,8 @@ build_packet(struct ra_iface *ra_iface)
        ra_options_conf = &ra_iface_conf->ra_options;
 
        len = sizeof(*ra);
+       if (ra_options_conf->mtu > 0)
+               len += sizeof(*ndopt_mtu);
        len += sizeof(*ndopt_pi) * ra_iface->prefix_count;
        if (ra_iface_conf->rdnss_count > 0)
                len += sizeof(*ndopt_rdnss) + ra_iface_conf->rdnss_count *
@@ -940,6 +943,15 @@ build_packet(struct ra_iface *ra_iface)
        ra->nd_ra_retransmit = htonl(ra_options_conf->retrans_timer);
        p += sizeof(*ra);
 
+       if (ra_options_conf->mtu > 0) {
+               ndopt_mtu = (struct nd_opt_mtu *)p;
+               ndopt_mtu->nd_opt_mtu_type = ND_OPT_MTU;
+               ndopt_mtu->nd_opt_mtu_len = 1;
+               ndopt_mtu->nd_opt_mtu_reserved = 0;
+               ndopt_mtu->nd_opt_mtu_mtu = htonl(ra_options_conf->mtu);
+               p += sizeof(*ndopt_mtu);
+       }
+
        SIMPLEQ_FOREACH(ra_prefix_conf, &ra_iface->prefixes, entry) {
                ndopt_pi = (struct nd_opt_prefix_info *)p;
                memset(ndopt_pi, 0, sizeof(*ndopt_pi));

diff --git a/usr.sbin/rad/parse.y b/usr.sbin/rad/parse.y
index 70c3819..e0a4e13 100644 (file)
--- a/usr.sbin/rad/parse.y
+++ b/usr.sbin/rad/parse.y
@@ -1,4 +1,4 @@
-/*     $OpenBSD: parse.y,v 1.5 2018/07/20 17:48:58 florian Exp $       */
+/*     $OpenBSD: parse.y,v 1.6 2018/07/20 17:55:09 bket Exp $  */
 
 /*
  * Copyright (c) 2018 Florian Obser <florian@openbsd.org>
@@ -115,7 +115,7 @@ typedef struct {
 %token DEFAULT ROUTER HOP LIMIT MANAGED ADDRESS
 %token CONFIGURATION OTHER LIFETIME REACHABLE TIME RETRANS TIMER
 %token AUTO PREFIX VALID PREFERRED LIFETIME ONLINK AUTONOMOUS
-%token ADDRESS_CONFIGURATION DNS NAMESERVER SEARCH
+%token ADDRESS_CONFIGURATION DNS NAMESERVER SEARCH MTU
 
 %token <v.string>      STRING
 %token <v.number>      NUMBER
@@ -209,6 +209,9 @@ ra_opt_block        : DEFAULT ROUTER yesno {
                | RETRANS TIMER NUMBER {
                        ra_options->retrans_timer = $3;
                }
+               | MTU NUMBER {
+                       ra_options->mtu = $2;
+               }
                ;
 
 optnl          : '\n' optnl            /* zero or more newlines */
@@ -424,6 +427,7 @@ lookup(char *s)
                {"lifetime",            LIFETIME},
                {"limit",               LIMIT},
                {"managed",             MANAGED},
+               {"mtu",                 MTU},
                {"nameserver",          NAMESERVER},
                {"no",                  NO},
                {"on-link",             ONLINK},

diff --git a/usr.sbin/rad/printconf.c b/usr.sbin/rad/printconf.c
index 1614fba..1f9e1f7 100644 (file)
--- a/usr.sbin/rad/printconf.c
+++ b/usr.sbin/rad/printconf.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: printconf.c,v 1.3 2018/07/20 13:17:02 florian Exp $   */
+/*     $OpenBSD: printconf.c,v 1.4 2018/07/20 17:55:09 bket Exp $      */
 
 /*
  * Copyright (c) 2018 Florian Obser <florian@openbsd.org>
@@ -54,6 +54,8 @@ print_ra_options(const char *indent, const struct ra_options_conf *ra_options)
        printf("%srouter lifetime %d\n", indent, ra_options->router_lifetime);
        printf("%sreachable time %u\n", indent, ra_options->reachable_time);
        printf("%sretrans timer %u\n", indent, ra_options->retrans_timer);
+       if (ra_options->mtu > 0)
+               printf("%smtu %u\n", indent, ra_options->mtu);
 }
 
 void

diff --git a/usr.sbin/rad/rad.c b/usr.sbin/rad/rad.c
index 4652e1e..7885066 100644 (file)
--- a/usr.sbin/rad/rad.c
+++ b/usr.sbin/rad/rad.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: rad.c,v 1.9 2018/07/18 14:43:34 florian Exp $ */
+/*     $OpenBSD: rad.c,v 1.10 2018/07/20 17:55:09 bket Exp $   */
 
 /*
  * Copyright (c) 2018 Florian Obser <florian@openbsd.org>
@@ -716,6 +716,7 @@ config_new_empty(void)
        xconf->ra_options.router_lifetime = 1800;
        xconf->ra_options.reachable_time = 0;
        xconf->ra_options.retrans_timer = 0;
+       xconf->ra_options.mtu = 0;
 
        return (xconf);
 }

diff --git a/usr.sbin/rad/rad.conf.5 b/usr.sbin/rad/rad.conf.5
index 36d1005..ee68834 100644 (file)
--- a/usr.sbin/rad/rad.conf.5
+++ b/usr.sbin/rad/rad.conf.5
@@ -1,4 +1,4 @@
-.\"    $OpenBSD: rad.conf.5,v 1.7 2018/07/20 13:17:02 florian Exp $
+.\"    $OpenBSD: rad.conf.5,v 1.8 2018/07/20 17:55:09 bket Exp $
 .\"
 .\" Copyright (c) 2018 Florian Obser <florian@openbsd.org>
 .\" Copyright (c) 2005 Esben Norby <norby@openbsd.org>
@@ -87,6 +87,11 @@ The default is 1800 seconds.
 .\" XXX
 .\" .It Ic retrans timer Ar number
 .\" XXX
+.It Ic mtu Ar bytes
+The MTU option is used in Router Advertisement messages to ensure that all
+nodes on a link use the same MTU value in those cases where the link MTU
+is not well known.
+The default is 0, meaning unspecified by this router.
 .El
 .Sh INTERFACES
 A list of interfaces to send advertisments on:

diff --git a/usr.sbin/rad/rad.h b/usr.sbin/rad/rad.h
index db80d7c..a8b8ba1 100644 (file)
--- a/usr.sbin/rad/rad.h
+++ b/usr.sbin/rad/rad.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: rad.h,v 1.11 2018/07/15 09:28:21 florian Exp $        */
+/*     $OpenBSD: rad.h,v 1.12 2018/07/20 17:55:09 bket Exp $   */
 
 /*
  * Copyright (c) 2018 Florian Obser <florian@openbsd.org>
@@ -76,7 +76,7 @@ enum imsg_type {
        IMSG_SOCKET_IPC
 };
 
-/* RFC 4861 Section 4.2 */
+/* RFC 4861 Sections 4.2 and 4.6.4 */
 struct ra_options_conf {
        int             dfr;                    /* is default router? */
        int             cur_hl;                 /* current hop limit */
@@ -85,6 +85,7 @@ struct ra_options_conf {
        int             router_lifetime;        /* default router lifetime */
        uint32_t        reachable_time;
        uint32_t        retrans_timer;
+       uint32_t        mtu;
 };
 
 /* RFC 4861 Section 4.6.2 */