diff options
| author | Tomas Hozza <thozza@redhat.com> | 2019-08-01 12:19:34 +0200 |
|---|---|---|
| committer | Tomas Hozza <thozza@redhat.com> | 2019-08-05 09:24:29 +0200 |
| commit | 2d48474e03798c6bf5281301fa818b94a0b5597d (patch) | |
| tree | f76b7d0c4944dfca4ea60219075a2b7fcbbf5c52 | |
| parent | ec3b947f6edb3c77bf921419094370e71e1ad415 (diff) | |
lib/prefix.c: ipv4_broadcast_addr() didn't comply with RFC3021
The function ipv4_broadcast_addr() does not calculate correct broadcast
addresses for point-to-point connections with prefix 31. RFC3021
section 3.3 [1] specifies:
"The 255.255.255.255 IP broadcast address MUST be used for broadcast
Address Mask Replies in point-to-point links with 31-bit subnet masks"
The issue causes Zebra to print the following warning when IPv4 address
with 31 prefix (e.g. 192.168.222.240/31) is configured on a network
interface:
ZEBRA: [EC 4043309141] warning: interface VNS broadcast addr 255.255.255.255/31 != calculated 192.168.222.241, routing protocols may malfunction
The issue has been originally found in Quagga [2], but it is present also
in FRR.
[1] https://tools.ietf.org/html/rfc3021#section-3.3
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1713449
Signed-off-by: Tomas Hozza <thozza@redhat.com>
| -rw-r--r-- | lib/prefix.c | 10 | ||||
| -rw-r--r-- | lib/prefix.h | 3 |
2 files changed, 6 insertions, 7 deletions
diff --git a/lib/prefix.c b/lib/prefix.c index 1a4a914e05..85bbb18f3d 100644 --- a/lib/prefix.c +++ b/lib/prefix.c @@ -1468,11 +1468,11 @@ in_addr_t ipv4_broadcast_addr(in_addr_t hostaddr, int masklen) masklen2ip(masklen, &mask); return (masklen != IPV4_MAX_PREFIXLEN - 1) ? - /* normal case */ - (hostaddr | ~mask.s_addr) - : - /* special case for /31 */ - (hostaddr ^ ~mask.s_addr); + /* normal case */ + (hostaddr | ~mask.s_addr) + : + /* For prefix 31 return 255.255.255.255 (RFC3021) */ + htonl(0xFFFFFFFF); } /* Utility function to convert ipv4 netmask to prefixes diff --git a/lib/prefix.h b/lib/prefix.h index e338140f1a..7a7e13518a 100644 --- a/lib/prefix.h +++ b/lib/prefix.h @@ -451,8 +451,7 @@ extern void masklen2ip(const int, struct in_addr *); extern in_addr_t ipv4_network_addr(in_addr_t hostaddr, int masklen); /* given the address of a host on a network and the network mask length, * calculate the broadcast address for that network; - * special treatment for /31: returns the address of the other host - * on the network by flipping the host bit */ + * special treatment for /31 according to RFC3021 section 3.3 */ extern in_addr_t ipv4_broadcast_addr(in_addr_t hostaddr, int masklen); extern int netmask_str2prefix_str(const char *, const char *, char *); |