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![Hannes Frederic Sowa](/assets/img/avatar_default.png)
Sockets marked with IP_PMTUDISC_INTERFACE won't do path mtu discovery, their sockets won't accept and install new path mtu information and they will always use the interface mtu for outgoing packets. It is guaranteed that the packet is not fragmented locally. But we won't set the DF-Flag on the outgoing frames. Florian Weimer had the idea to use this flag to ensure DNS servers are never generating outgoing fragments. They may well be fragmented on the path, but the server never stores or usees path mtu values, which could well be forged in an attack. (The root of the problem with path MTU discovery is that there is no reliable way to authenticate ICMP Fragmentation Needed But DF Set messages because they are sent from intermediate routers with their source addresses, and the IMCP payload will not always contain sufficient information to identify a flow.) Recent research in the DNS community showed that it is possible to implement an attack where DNS cache poisoning is feasible by spoofing fragments. This work was done by Amir Herzberg and Haya Shulman: <https://sites.google.com/site/hayashulman/files/fragmentation-poisoning.pdf> This issue was previously discussed among the DNS community, e.g. <http://www.ietf.org/mail-archive/web/dnsext/current/msg01204.html>, without leading to fixes. This patch depends on the patch "ipv4: fix DO and PROBE pmtu mode regarding local fragmentation with UFO/CORK" for the enforcement of the non-fragmentable checks. If other users than ip_append_page/data should use this semantic too, we have to add a new flag to IPCB(skb)->flags to suppress local fragmentation and check for this in ip_finish_output. Many thanks to Florian Weimer for the idea and feedback while implementing this patch. Cc: David S. Miller <davem@davemloft.net> Suggested-by: Florian Weimer <fweimer@redhat.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
281 lines
8.9 KiB
C
281 lines
8.9 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _UAPI_LINUX_IN_H
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#define _UAPI_LINUX_IN_H
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#include <linux/types.h>
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#include <linux/socket.h>
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/* Standard well-defined IP protocols. */
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enum {
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IPPROTO_IP = 0, /* Dummy protocol for TCP */
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#define IPPROTO_IP IPPROTO_IP
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IPPROTO_ICMP = 1, /* Internet Control Message Protocol */
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#define IPPROTO_ICMP IPPROTO_ICMP
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IPPROTO_IGMP = 2, /* Internet Group Management Protocol */
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#define IPPROTO_IGMP IPPROTO_IGMP
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IPPROTO_IPIP = 4, /* IPIP tunnels (older KA9Q tunnels use 94) */
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#define IPPROTO_IPIP IPPROTO_IPIP
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IPPROTO_TCP = 6, /* Transmission Control Protocol */
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#define IPPROTO_TCP IPPROTO_TCP
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IPPROTO_EGP = 8, /* Exterior Gateway Protocol */
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#define IPPROTO_EGP IPPROTO_EGP
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IPPROTO_PUP = 12, /* PUP protocol */
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#define IPPROTO_PUP IPPROTO_PUP
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IPPROTO_UDP = 17, /* User Datagram Protocol */
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#define IPPROTO_UDP IPPROTO_UDP
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IPPROTO_IDP = 22, /* XNS IDP protocol */
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#define IPPROTO_IDP IPPROTO_IDP
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IPPROTO_TP = 29, /* SO Transport Protocol Class 4 */
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#define IPPROTO_TP IPPROTO_TP
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IPPROTO_DCCP = 33, /* Datagram Congestion Control Protocol */
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#define IPPROTO_DCCP IPPROTO_DCCP
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IPPROTO_IPV6 = 41, /* IPv6-in-IPv4 tunnelling */
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#define IPPROTO_IPV6 IPPROTO_IPV6
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IPPROTO_RSVP = 46, /* RSVP Protocol */
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#define IPPROTO_RSVP IPPROTO_RSVP
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IPPROTO_GRE = 47, /* Cisco GRE tunnels (rfc 1701,1702) */
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#define IPPROTO_GRE IPPROTO_GRE
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IPPROTO_ESP = 50, /* Encapsulation Security Payload protocol */
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#define IPPROTO_ESP IPPROTO_ESP
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IPPROTO_AH = 51, /* Authentication Header protocol */
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#define IPPROTO_AH IPPROTO_AH
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IPPROTO_MTP = 92, /* Multicast Transport Protocol */
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#define IPPROTO_MTP IPPROTO_MTP
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IPPROTO_BEETPH = 94, /* IP option pseudo header for BEET */
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#define IPPROTO_BEETPH IPPROTO_BEETPH
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IPPROTO_ENCAP = 98, /* Encapsulation Header */
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#define IPPROTO_ENCAP IPPROTO_ENCAP
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IPPROTO_PIM = 103, /* Protocol Independent Multicast */
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#define IPPROTO_PIM IPPROTO_PIM
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IPPROTO_COMP = 108, /* Compression Header Protocol */
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#define IPPROTO_COMP IPPROTO_COMP
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IPPROTO_SCTP = 132, /* Stream Control Transport Protocol */
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#define IPPROTO_SCTP IPPROTO_SCTP
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IPPROTO_UDPLITE = 136, /* UDP-Lite (RFC 3828) */
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#define IPPROTO_UDPLITE IPPROTO_UDPLITE
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IPPROTO_RAW = 255, /* Raw IP packets */
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#define IPPROTO_RAW IPPROTO_RAW
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IPPROTO_MAX
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};
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/* Internet address. */
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struct in_addr {
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__be32 s_addr;
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};
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#define IP_TOS 1
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#define IP_TTL 2
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#define IP_HDRINCL 3
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#define IP_OPTIONS 4
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#define IP_ROUTER_ALERT 5
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#define IP_RECVOPTS 6
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#define IP_RETOPTS 7
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#define IP_PKTINFO 8
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#define IP_PKTOPTIONS 9
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#define IP_MTU_DISCOVER 10
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#define IP_RECVERR 11
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#define IP_RECVTTL 12
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#define IP_RECVTOS 13
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#define IP_MTU 14
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#define IP_FREEBIND 15
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#define IP_IPSEC_POLICY 16
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#define IP_XFRM_POLICY 17
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#define IP_PASSSEC 18
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#define IP_TRANSPARENT 19
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/* BSD compatibility */
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#define IP_RECVRETOPTS IP_RETOPTS
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/* TProxy original addresses */
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#define IP_ORIGDSTADDR 20
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#define IP_RECVORIGDSTADDR IP_ORIGDSTADDR
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#define IP_MINTTL 21
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#define IP_NODEFRAG 22
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/* IP_MTU_DISCOVER values */
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#define IP_PMTUDISC_DONT 0 /* Never send DF frames */
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#define IP_PMTUDISC_WANT 1 /* Use per route hints */
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#define IP_PMTUDISC_DO 2 /* Always DF */
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#define IP_PMTUDISC_PROBE 3 /* Ignore dst pmtu */
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/* Always use interface mtu (ignores dst pmtu) but don't set DF flag.
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* Also incoming ICMP frag_needed notifications will be ignored on
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* this socket to prevent accepting spoofed ones.
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*/
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#define IP_PMTUDISC_INTERFACE 4
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#define IP_MULTICAST_IF 32
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#define IP_MULTICAST_TTL 33
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#define IP_MULTICAST_LOOP 34
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#define IP_ADD_MEMBERSHIP 35
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#define IP_DROP_MEMBERSHIP 36
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#define IP_UNBLOCK_SOURCE 37
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#define IP_BLOCK_SOURCE 38
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#define IP_ADD_SOURCE_MEMBERSHIP 39
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#define IP_DROP_SOURCE_MEMBERSHIP 40
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#define IP_MSFILTER 41
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#define MCAST_JOIN_GROUP 42
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#define MCAST_BLOCK_SOURCE 43
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#define MCAST_UNBLOCK_SOURCE 44
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#define MCAST_LEAVE_GROUP 45
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#define MCAST_JOIN_SOURCE_GROUP 46
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#define MCAST_LEAVE_SOURCE_GROUP 47
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#define MCAST_MSFILTER 48
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#define IP_MULTICAST_ALL 49
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#define IP_UNICAST_IF 50
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#define MCAST_EXCLUDE 0
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#define MCAST_INCLUDE 1
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/* These need to appear somewhere around here */
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#define IP_DEFAULT_MULTICAST_TTL 1
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#define IP_DEFAULT_MULTICAST_LOOP 1
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/* Request struct for multicast socket ops */
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struct ip_mreq {
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struct in_addr imr_multiaddr; /* IP multicast address of group */
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struct in_addr imr_interface; /* local IP address of interface */
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};
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struct ip_mreqn {
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struct in_addr imr_multiaddr; /* IP multicast address of group */
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struct in_addr imr_address; /* local IP address of interface */
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int imr_ifindex; /* Interface index */
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};
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struct ip_mreq_source {
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__be32 imr_multiaddr;
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__be32 imr_interface;
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__be32 imr_sourceaddr;
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};
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struct ip_msfilter {
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__be32 imsf_multiaddr;
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__be32 imsf_interface;
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__u32 imsf_fmode;
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__u32 imsf_numsrc;
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__be32 imsf_slist[1];
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};
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#define IP_MSFILTER_SIZE(numsrc) \
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(sizeof(struct ip_msfilter) - sizeof(__u32) \
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+ (numsrc) * sizeof(__u32))
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struct group_req {
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__u32 gr_interface; /* interface index */
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struct __kernel_sockaddr_storage gr_group; /* group address */
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};
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struct group_source_req {
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__u32 gsr_interface; /* interface index */
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struct __kernel_sockaddr_storage gsr_group; /* group address */
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struct __kernel_sockaddr_storage gsr_source; /* source address */
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};
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struct group_filter {
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__u32 gf_interface; /* interface index */
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struct __kernel_sockaddr_storage gf_group; /* multicast address */
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__u32 gf_fmode; /* filter mode */
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__u32 gf_numsrc; /* number of sources */
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struct __kernel_sockaddr_storage gf_slist[1]; /* interface index */
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};
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#define GROUP_FILTER_SIZE(numsrc) \
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(sizeof(struct group_filter) - sizeof(struct __kernel_sockaddr_storage) \
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+ (numsrc) * sizeof(struct __kernel_sockaddr_storage))
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struct in_pktinfo {
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int ipi_ifindex;
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struct in_addr ipi_spec_dst;
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struct in_addr ipi_addr;
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};
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/* Structure describing an Internet (IP) socket address. */
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#define __SOCK_SIZE__ 16 /* sizeof(struct sockaddr) */
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struct sockaddr_in {
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__kernel_sa_family_t sin_family; /* Address family */
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__be16 sin_port; /* Port number */
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struct in_addr sin_addr; /* Internet address */
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/* Pad to size of `struct sockaddr'. */
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unsigned char __pad[__SOCK_SIZE__ - sizeof(short int) -
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sizeof(unsigned short int) - sizeof(struct in_addr)];
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};
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#define sin_zero __pad /* for BSD UNIX comp. -FvK */
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/*
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* Definitions of the bits in an Internet address integer.
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* On subnets, host and network parts are found according
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* to the subnet mask, not these masks.
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*/
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#define IN_CLASSA(a) ((((long int) (a)) & 0x80000000) == 0)
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#define IN_CLASSA_NET 0xff000000
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#define IN_CLASSA_NSHIFT 24
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#define IN_CLASSA_HOST (0xffffffff & ~IN_CLASSA_NET)
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#define IN_CLASSA_MAX 128
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#define IN_CLASSB(a) ((((long int) (a)) & 0xc0000000) == 0x80000000)
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#define IN_CLASSB_NET 0xffff0000
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#define IN_CLASSB_NSHIFT 16
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#define IN_CLASSB_HOST (0xffffffff & ~IN_CLASSB_NET)
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#define IN_CLASSB_MAX 65536
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#define IN_CLASSC(a) ((((long int) (a)) & 0xe0000000) == 0xc0000000)
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#define IN_CLASSC_NET 0xffffff00
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#define IN_CLASSC_NSHIFT 8
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#define IN_CLASSC_HOST (0xffffffff & ~IN_CLASSC_NET)
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#define IN_CLASSD(a) ((((long int) (a)) & 0xf0000000) == 0xe0000000)
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#define IN_MULTICAST(a) IN_CLASSD(a)
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#define IN_MULTICAST_NET 0xF0000000
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#define IN_EXPERIMENTAL(a) ((((long int) (a)) & 0xf0000000) == 0xf0000000)
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#define IN_BADCLASS(a) IN_EXPERIMENTAL((a))
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/* Address to accept any incoming messages. */
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#define INADDR_ANY ((unsigned long int) 0x00000000)
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/* Address to send to all hosts. */
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#define INADDR_BROADCAST ((unsigned long int) 0xffffffff)
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/* Address indicating an error return. */
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#define INADDR_NONE ((unsigned long int) 0xffffffff)
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/* Network number for local host loopback. */
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#define IN_LOOPBACKNET 127
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/* Address to loopback in software to local host. */
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#define INADDR_LOOPBACK 0x7f000001 /* 127.0.0.1 */
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#define IN_LOOPBACK(a) ((((long int) (a)) & 0xff000000) == 0x7f000000)
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/* Defines for Multicast INADDR */
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#define INADDR_UNSPEC_GROUP 0xe0000000U /* 224.0.0.0 */
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#define INADDR_ALLHOSTS_GROUP 0xe0000001U /* 224.0.0.1 */
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#define INADDR_ALLRTRS_GROUP 0xe0000002U /* 224.0.0.2 */
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#define INADDR_MAX_LOCAL_GROUP 0xe00000ffU /* 224.0.0.255 */
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/* <asm/byteorder.h> contains the htonl type stuff.. */
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#include <asm/byteorder.h>
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#endif /* _UAPI_LINUX_IN_H */
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