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96125bf998
The longstanding prohibition against using 0.0.0.0/8 dates back to two issues with the early internet. There was an interoperability problem with BSD 4.2 in 1984, fixed in BSD 4.3 in 1986. BSD 4.2 has long since been retired. Secondly, addresses of the form 0.x.y.z were initially defined only as a source address in an ICMP datagram, indicating "node number x.y.z on this IPv4 network", by nodes that know their address on their local network, but do not yet know their network prefix, in RFC0792 (page 19). This usage of 0.x.y.z was later repealed in RFC1122 (section 3.2.2.7), because the original ICMP-based mechanism for learning the network prefix was unworkable on many networks such as Ethernet (which have longer addresses that would not fit into the 24 "node number" bits). Modern networks use reverse ARP (RFC0903) or BOOTP (RFC0951) or DHCP (RFC2131) to find their full 32-bit address and CIDR netmask (and other parameters such as default gateways). 0.x.y.z has had 16,777,215 addresses in 0.0.0.0/8 space left unused and reserved for future use, since 1989. This patch allows for these 16m new IPv4 addresses to appear within a box or on the wire. Layer 2 switches don't care. 0.0.0.0/32 is still prohibited, of course. Signed-off-by: Dave Taht <dave.taht@gmail.com> Signed-off-by: John Gilmore <gnu@toad.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
106 lines
2.3 KiB
C
106 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* Definitions of the Internet Protocol.
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*
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* Version: @(#)in.h 1.0.1 04/21/93
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*
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* Authors: Original taken from the GNU Project <netinet/in.h> file.
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* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
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*/
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#ifndef _LINUX_IN_H
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#define _LINUX_IN_H
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#include <linux/errno.h>
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#include <uapi/linux/in.h>
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static inline int proto_ports_offset(int proto)
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{
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switch (proto) {
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case IPPROTO_TCP:
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case IPPROTO_UDP:
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case IPPROTO_DCCP:
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case IPPROTO_ESP: /* SPI */
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case IPPROTO_SCTP:
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case IPPROTO_UDPLITE:
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return 0;
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case IPPROTO_AH: /* SPI */
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return 4;
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default:
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return -EINVAL;
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}
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}
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static inline bool ipv4_is_loopback(__be32 addr)
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{
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return (addr & htonl(0xff000000)) == htonl(0x7f000000);
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}
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static inline bool ipv4_is_multicast(__be32 addr)
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{
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return (addr & htonl(0xf0000000)) == htonl(0xe0000000);
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}
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static inline bool ipv4_is_local_multicast(__be32 addr)
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{
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return (addr & htonl(0xffffff00)) == htonl(0xe0000000);
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}
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static inline bool ipv4_is_lbcast(__be32 addr)
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{
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/* limited broadcast */
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return addr == htonl(INADDR_BROADCAST);
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}
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static inline bool ipv4_is_all_snoopers(__be32 addr)
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{
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return addr == htonl(INADDR_ALLSNOOPERS_GROUP);
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}
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static inline bool ipv4_is_zeronet(__be32 addr)
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{
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return (addr == 0);
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}
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/* Special-Use IPv4 Addresses (RFC3330) */
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static inline bool ipv4_is_private_10(__be32 addr)
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{
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return (addr & htonl(0xff000000)) == htonl(0x0a000000);
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}
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static inline bool ipv4_is_private_172(__be32 addr)
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{
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return (addr & htonl(0xfff00000)) == htonl(0xac100000);
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}
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static inline bool ipv4_is_private_192(__be32 addr)
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{
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return (addr & htonl(0xffff0000)) == htonl(0xc0a80000);
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}
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static inline bool ipv4_is_linklocal_169(__be32 addr)
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{
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return (addr & htonl(0xffff0000)) == htonl(0xa9fe0000);
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}
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static inline bool ipv4_is_anycast_6to4(__be32 addr)
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{
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return (addr & htonl(0xffffff00)) == htonl(0xc0586300);
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}
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static inline bool ipv4_is_test_192(__be32 addr)
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{
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return (addr & htonl(0xffffff00)) == htonl(0xc0000200);
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}
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static inline bool ipv4_is_test_198(__be32 addr)
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{
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return (addr & htonl(0xfffe0000)) == htonl(0xc6120000);
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}
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#endif /* _LINUX_IN_H */
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