240.0.0.0/4 is marked as reserved and considered invalid by BIRD. At work, we are using this range internally since all RFC 1918 are full and 100.64.0.0/10 is already used too. BIRD complains loudly for each interface using this range.
This change makes it possible to use this range. I have used scope "universe". But I would be happy with "site" too. While widely discussed, I don't think 240/4 will become routable on the Internet one day. As a bonus, I added some comments and unrolled a condition for each block. I also have added some hints for the compiler to avoid using jumps in the hotpath (tested on Godbolt, see https://godbolt.org/z/rGjz336K3). --- lib/ip.c | 28 +++++++++++----------------- sysdep/config.h | 5 +++++ 2 files changed, 16 insertions(+), 17 deletions(-) diff --git a/lib/ip.c b/lib/ip.c index fcc72cafb4de..4d0dff636e17 100644 --- a/lib/ip.c +++ b/lib/ip.c @@ -85,25 +85,19 @@ ip4_classify(ip4_addr ad) u32 a = _I(ad); u32 b = a >> 24U; - if (b && b <= 0xdf) - { - if (b == 0x7f) - return IADDR_HOST | SCOPE_HOST; - else if ((b == 0x0a) || - ((a & 0xffff0000) == 0xc0a80000) || - ((a & 0xfff00000) == 0xac100000)) - return IADDR_HOST | SCOPE_SITE; - else - return IADDR_HOST | SCOPE_UNIVERSE; - } - - if (b >= 0xe0 && b <= 0xef) + if (unlikely(b == 0x00)) + return IADDR_INVALID; /* 0.0.0.0/8 This network */ + if (unlikely(b == 0x7f)) /* 127.0.0.0/8 Loopback */ + return IADDR_HOST | SCOPE_HOST; + if ((b == 0x0a) || /* 10.0.0.0/8 Private-use */ + ((a & 0xffff0000) == 0xc0a80000) || /* 192.168.0.0/16 Private-use */ + ((a & 0xfff00000) == 0xac100000)) /* 172.16.0.0/12 Private-use */ + return IADDR_HOST | SCOPE_SITE; + if (unlikely(b >= 0xe0 && b <= 0xef)) /* 224.0.0.0/4 Multicast */ return IADDR_MULTICAST | SCOPE_UNIVERSE; - - if (a == 0xffffffff) + if (unlikely(a == 0xffffffff)) /* 255.255.255.255 Limited broadcast */ return IADDR_BROADCAST | SCOPE_LINK; - - return IADDR_INVALID; + return IADDR_HOST | SCOPE_UNIVERSE; } int diff --git a/sysdep/config.h b/sysdep/config.h index b0531844af9f..4d73543c3894 100644 --- a/sysdep/config.h +++ b/sysdep/config.h @@ -30,6 +30,11 @@ */ #include "sysdep/paths.h" +/* Likely/unlikely macros */ + +#define likely(x) __builtin_expect((x),1) +#define unlikely(x) __builtin_expect((x),0) + /* Types */ #include <stdint.h> -- 2.35.1
