Fixes a compatibility issue in OSPFv2 PtP links.

BIRD used zero netmask in hello packets on all PtP links, not just on
unnumbered ones. This patch fixes it and adds option 'ptp netmask'
for overriding the default behavior.

Thanks to Alexander V. Chernikov for the original patch.

4 files changed, 10 insertions, 2 deletions

diff --git a/proto/ospf/config.Y b/proto/ospf/config.Y
index b16d46a9..2cc0b963 100644
--- a/proto/ospf/config.Y
+++ b/proto/ospf/config.Y
@@ -131,7 +131,7 @@ CF_KEYWORDS(NONE, SIMPLE, AUTHENTICATION, STRICT, CRYPTOGRAPHIC)
 CF_KEYWORDS(ELIGIBLE, POLL, NETWORKS, HIDDEN, VIRTUAL, CHECK, LINK)
 CF_KEYWORDS(RX, BUFFER, LARGE, NORMAL, STUBNET, HIDDEN, SUMMARY, TAG, EXTERNAL)
 CF_KEYWORDS(WAIT, DELAY, LSADB, ECMP, LIMIT, WEIGHT, NSSA, TRANSLATOR, STABILITY)
-CF_KEYWORDS(GLOBAL, LSID, ROUTER, SELF, INSTANCE, REAL)
+CF_KEYWORDS(GLOBAL, LSID, ROUTER, SELF, INSTANCE, REAL, NETMASK)
 
 %type <t> opttext
 %type <ld> lsadb_args
@@ -290,6 +290,7 @@ ospf_iface_item:
  | TYPE POINTOMULTIPOINT { OSPF_PATT->type = OSPF_IT_PTMP ; }
  | TYPE PTMP { OSPF_PATT->type = OSPF_IT_PTMP ; }
  | REAL BROADCAST bool { OSPF_PATT->real_bcast = $3; if (OSPF_VERSION != 2) cf_error("Real broadcast option requires OSPFv2"); }
+ | PTP NETMASK bool { OSPF_PATT->ptp_netmask = $3; if (OSPF_VERSION != 2) cf_error("Real netmask option requires OSPFv2"); }
  | TRANSMIT DELAY expr { OSPF_PATT->inftransdelay = $3 ; if (($3<=0) || ($3>65535)) cf_error("Transmit delay must be in range 1-65535"); }
  | PRIORITY expr { OSPF_PATT->priority = $2 ; if (($2<0) || ($2>255)) cf_error("Priority must be in range 0-255"); }
  | STRICT NONBROADCAST bool { OSPF_PATT->strictnbma = $3 ; }
@@ -364,6 +365,7 @@ ospf_iface_start:
   OSPF_PATT->type = OSPF_IT_UNDEF;
   init_list(&OSPF_PATT->nbma_list);
   OSPF_PATT->autype = OSPF_AUTH_NONE;
+  OSPF_PATT->ptp_netmask = 2; /* not specified */
   reset_passwords();
  }
 ;
diff --git a/proto/ospf/hello.c b/proto/ospf/hello.c
index 6ec5c511..d5aa1b95 100644
--- a/proto/ospf/hello.c
+++ b/proto/ospf/hello.c
@@ -253,7 +253,8 @@ ospf_hello_send(struct ospf_iface *ifa, int kind, struct ospf_neighbor *dirn)
 #ifdef OSPFv2
   pkt->netmask = ipa_mkmask(ifa->addr->pxlen);
   ipa_hton(pkt->netmask);
-  if ((ifa->type == OSPF_IT_VLINK) || (ifa->type == OSPF_IT_PTP))
+  if ((ifa->type == OSPF_IT_VLINK) ||
+      ((ifa->type == OSPF_IT_PTP) && !ifa->ptp_netmask))
     pkt->netmask = IPA_NONE;
 #endif
 
diff --git a/proto/ospf/iface.c b/proto/ospf/iface.c
index 39084cef..9050f7b1 100644
--- a/proto/ospf/iface.c
+++ b/proto/ospf/iface.c
@@ -537,6 +537,9 @@ ospf_iface_new(struct ospf_area *oa, struct ifa *addr, struct ospf_iface_patt *i
 #ifdef OSPFv2
   ifa->autype = ip->autype;
   ifa->passwords = ip->passwords;
+  ifa->ptp_netmask = !(addr->flags & IA_PEER);
+  if (ip->ptp_netmask < 2)
+    ifa->ptp_netmask = ip->ptp_netmask;
 #endif
 
 #ifdef OSPFv3
diff --git a/proto/ospf/ospf.h b/proto/ospf/ospf.h
index 7111a13d..d924e657 100644
--- a/proto/ospf/ospf.h
+++ b/proto/ospf/ospf.h
@@ -273,6 +273,7 @@ struct ospf_iface
   u16 rxbuf;			/* Buffer size */
   u8 check_link;		/* Whether iface link change is used */
   u8 ecmp_weight;		/* Weight used for ECMP */
+  u8 ptp_netmask;		/* Send real netmask for P2P */
 };
 
 struct ospf_md5
@@ -810,6 +811,7 @@ struct ospf_iface_patt
   u8 check_link;
   u8 ecmp_weight;
   u8 real_bcast;		/* Not really used in OSPFv3 */
+  u8 ptp_netmask;		/* bool but 2 for unspecified */
 
 #ifdef OSPFv2
   list *passwords;