router: rename minvalid to lowest_found_lifetime

The variable is used across all prefix lifetimes, serving as a low-tide
mark. It stores the lowest lifetime among all prefixes.

Signed-off-by: Paul Donald <newtwen@gmail.com>
[ fix comment format ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

diff --git a/src/router.c b/src/router.c
index 7075a6a52301ae56a37872bee947584e59fa41cb..8721c37706ed884049077688d4b882a27e1d00b3 100644 (file)
--- a/src/router.c
+++ b/src/router.c
@@ -334,7 +334,7 @@ static bool parse_routes(struct odhcpd_ipaddr *n, ssize_t len)
        return found_default;
 }
 
-static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
+static int calc_adv_interval(struct interface *iface, uint32_t lowest_found_lifetime,
                                uint32_t *maxival)
 {
        uint32_t minival = iface->ra_mininterval;
@@ -342,8 +342,13 @@ static int calc_adv_interval(struct interface *iface, uint32_t minvalid,
 
        *maxival = iface->ra_maxinterval;
 
-       if (*maxival > minvalid/3)
-               *maxival = minvalid/3;
+       /* 
+        * rfc4861#section-6.2.1 : AdvDefaultLifetime Default: 3 * MaxRtrAdvInterval
+        * therefore max interval shall be no greater than 1/3 of the lowest valid
+        * lease time of all known prefixes.
+        */
+       if (*maxival > lowest_found_lifetime/3)
+               *maxival = lowest_found_lifetime/3;
 
        if (*maxival > MaxRtrAdvInterval)
                *maxival = MaxRtrAdvInterval;
@@ -452,7 +457,12 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
        size_t dns_sz = 0, search_sz = 0, pref64_sz = 0;
        size_t pfxs_cnt = 0, routes_cnt = 0;
        ssize_t valid_addr_cnt = 0, invalid_addr_cnt = 0;
-       uint32_t minvalid = UINT32_MAX, maxival, lifetime;
+       /* 
+        * lowest_found_lifetime stores the lowest lifetime of all prefixes;
+        * necessary to find shortest adv interval necessary
+        * for shortest lived prefix
+        */
+       uint32_t lowest_found_lifetime = UINT32_MAX, maxival, lifetime;
        int msecs, mtu = iface->ra_mtu, hlim = iface->ra_hoplimit;
        bool default_route = false;
        bool valid_prefix = false;
@@ -612,8 +622,8 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
                        preferred_lt = valid_lt;
                }
 
-               if (minvalid > valid_lt)
-                       minvalid = valid_lt;
+               if (lowest_found_lifetime > valid_lt)
+                       lowest_found_lifetime = valid_lt;
 
                if ((!IN6_IS_ADDR_ULA(&addr->addr.in6) || iface->default_router) && valid_lt)
                        valid_prefix = true;
@@ -638,7 +648,7 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
        iov[IOV_RA_PFXS].iov_len = pfxs_cnt * sizeof(*pfxs);
 
        /* Calculate periodic transmit */
-       msecs = calc_adv_interval(iface, minvalid, &maxival);
+       msecs = calc_adv_interval(iface, lowest_found_lifetime, &maxival);
        lifetime = calc_ra_lifetime(iface, maxival);
 
        if (!iface->have_link_local) {