143 lines
5.8 KiB
C
143 lines
5.8 KiB
C
/*
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* The mrouted program is covered by the license in the accompanying file
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* named "LICENSE". Use of the mrouted program represents acceptance of
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* the terms and conditions listed in that file.
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*
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* The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
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* Leland Stanford Junior University.
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*
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*
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* From: Id: dvmrp.h,v 1.3 1993/05/30 01:36:38 deering Exp $
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* $Id: dvmrp.h,v 1.2 1994/05/08 15:08:53 brezak Exp $
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*/
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/*
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* A DVMRP message consists of an IP header + an IGMP header + (for some types)
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* zero or more bytes of data.
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*
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* For REPORT messages, the data is route information; the route information
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* consists of one or more lists of the following form:
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*
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* (mask, (origin, metric), (origin, metric), ...)
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*
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* where:
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*
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* "mask" is the subnet mask for all the origins in the list.
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* It is always THREE bytes long, containing the low-order
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* three bytes of the mask (the high-order byte is always
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* 0xff and therefore need not be transmitted).
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*
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* "origin" is the number of a subnet from which multicast datagrams
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* may originate. It is from one to four bytes long,
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* depending on the value of "mask":
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* if all bytes of the mask are zero
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* the subnet number is one byte long
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* else if the low-order two bytes of the mask are zero
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* the subnet number is two bytes long
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* else if the lowest-order byte of the mask is zero
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* the subnet number is three bytes long,
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* else
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* the subnet number is four bytes long.
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*
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* "metric" is a one-byte value consisting of two subfields:
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* - the high-order bit is a flag which, when set, indicates
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* the last (origin, metric) pair of a list.
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* - the low-order seven bits contain the routing metric for
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* the corresponding origin, relative to the sender of the
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* DVMRP report. The metric may have the value of UNREACHABLE
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* added to it as a "split horizon" indication (so called
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* "poisoned reverse").
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*
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* Within a list, the origin subnet numbers must be in ascending order, and
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* the lists themselves are in order of increasing mask value. A message may
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* not exceed 576 bytes, the default maximum IP reassembly size, including
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* the IP and IGMP headers; the route information may be split across more
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* than one message if necessary, by terminating a list in one message and
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* starting a new list in the next message (repeating the same mask value,
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* if necessary).
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*
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* For NEIGHBORS messages, the data is neighboring-router information
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* consisting of one or more lists of the following form:
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*
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* (local-addr, metric, threshold, ncount, neighbor, neighbor, ...)
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*
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* where:
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*
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* "local-addr" is the sending router's address as seen by the neighbors
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* in this list; it is always four bytes long.
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* "metric" is a one-byte unsigned value, the TTL `cost' of forwarding
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* packets to any of the neighbors on this list.
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* "threshold" is a one-byte unsigned value, a lower bound on the TTL a
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* packet must have to be forwarded to any of the neighbors on
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* this list.
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* "ncount" is the number of neighbors in this list.
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* "neighbor" is the address of a neighboring router, four bytes long.
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*
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* As with REPORT messages, NEIGHBORS messages should not exceed 576 bytes,
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* including the IP and IGMP headers; split longer messages by terminating the
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* list in one and continuing in another, repeating the local-addr, etc., if
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* necessary.
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*
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* For NEIGHBORS2 messages, the data is identical to NEIGHBORS except
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* there is a flags byte before the neighbor count:
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*
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* (local-addr, metric, threshold, flags, ncount, neighbor, neighbor, ...)
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*/
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/*
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* DVMRP message types (carried in the "code" field of an IGMP header)
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*/
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#define DVMRP_PROBE 1 /* for finding neighbors */
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#define DVMRP_REPORT 2 /* for reporting some or all routes */
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#define DVMRP_ASK_NEIGHBORS 3 /* sent by mapper, asking for a list */
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/* of this router's neighbors. */
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#define DVMRP_NEIGHBORS 4 /* response to such a request */
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#define DVMRP_ASK_NEIGHBORS2 5 /* as above, want new format reply */
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#define DVMRP_NEIGHBORS2 6
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/*
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* 'flags' byte values in DVMRP_NEIGHBORS2 reply.
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*/
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#define DVMRP_NF_TUNNEL 0x01 /* neighbors reached via tunnel */
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#define DVMRP_NF_SRCRT 0x02 /* tunnel uses IP source routing */
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#define DVMRP_NF_DOWN 0x10 /* kernel state of interface */
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#define DVMRP_NF_DISABLED 0x20 /* administratively disabled */
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#define DVMRP_NF_QUERIER 0x40 /* I am the subnet's querier */
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/*
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* Limit on length of route data
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*/
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#define MAX_IP_PACKET_LEN 576
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#define MIN_IP_HEADER_LEN 20
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#define MAX_IP_HEADER_LEN 60
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#define MAX_DVMRP_DATA_LEN \
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( MAX_IP_PACKET_LEN - MAX_IP_HEADER_LEN - IGMP_MINLEN )
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/*
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* Various protocol constants (all times in seconds)
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*/
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/* address for multicast DVMRP msgs */
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#define INADDR_DVMRP_GROUP (u_long)0xe0000004 /* 224.0.0.4 */
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#define ROUTE_MAX_REPORT_DELAY 5 /* max delay for reporting changes */
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/* (This is the timer interrupt */
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/* interval; all times must be */
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/* multiples of this value.) */
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#define ROUTE_REPORT_INTERVAL 60 /* periodic route report interval */
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#define ROUTE_SWITCH_TIME 140 /* time to switch to equivalent gw */
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#define ROUTE_EXPIRE_TIME 200 /* time to mark route invalid */
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#define ROUTE_DISCARD_TIME 340 /* time to garbage collect route */
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#define LEAF_CONFIRMATION_TIME 200 /* time to consider subnet a leaf */
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#define NEIGHBOR_PROBE_INTERVAL 190 /* periodic neighbor probe interval */
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#define NEIGHBOR_EXPIRE_TIME 140 /* time to consider neighbor gone */
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#define GROUP_QUERY_INTERVAL 125 /* periodic group query interval */
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#define GROUP_EXPIRE_TIME 270 /* time to consider group gone */
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#define UNREACHABLE 32 /* "infinity" metric, must be <= 64 */
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#define DEFAULT_METRIC 1 /* default subnet/tunnel metric */
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#define DEFAULT_THRESHOLD 1 /* default subnet/tunnel threshold */
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