[PATCH odhcpd 1/2] router: improve RA logging

[stijn at linux-ipv6.be]

We only set the RA lifetime to what is configured in UCI when there is a
default route and valid prefix. In any other case, we set it to 0. This
leads to confusion where people believe ra_lifetime is completely
ignored. In case there is a default route, but no valid prefix, a debug
message explains this, but if there is no default route, we silently
override ra_lifetime.

Add a debug message for the latter case, and explicitly mention
overriding ra_lifetime in both cases.

Signed-off-by: Stijn Tintel <stijn at linux-ipv6.be>
---
 src/router.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/router.c b/src/router.c
index 949cbe7..1c11849 100644
--- a/src/router.c
+++ b/src/router.c
@@ -618,17 +618,19 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
 	msecs = calc_adv_interval(iface, minvalid, &maxival);
 	lifetime = calc_ra_lifetime(iface, maxival);
 
-	if (default_route) {
-		if (!valid_prefix) {
-			syslog(LOG_WARNING, "A default route is present but there is no public prefix "
-					"on %s thus we don't announce a default route!", iface->name);
-			adv.h.nd_ra_router_lifetime = 0;
-		} else
-			adv.h.nd_ra_router_lifetime = htons(lifetime < UINT16_MAX ? lifetime : UINT16_MAX);
-
-	} else
+	if (default_route && valid_prefix) {
+		adv.h.nd_ra_router_lifetime = htons(lifetime < UINT16_MAX ? lifetime : UINT16_MAX);
+	} else {
 		adv.h.nd_ra_router_lifetime = 0;
 
+		if (default_route) {
+			syslog(LOG_WARNING, "A default route is present but there is no public prefix "
+					    "on %s thus we don't announce a default route by overriding ra_lifetime!", iface->name);
+		} else {
+			syslog(LOG_WARNING, "No default route present, overriding ra_lifetime!");
+		}
+	}
+
 	syslog(LOG_DEBUG, "Using a RA lifetime of %d seconds on %s", ntohs(adv.h.nd_ra_router_lifetime), iface->name);
 
 	/* DNS options */
-- 
2.39.1