ubgpsuite/tools/bgpgrep/bgpgrep_dump.c

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// SPDX-License-Identifier: GPL-3.0-or-later
/**
* \file bgpgrep_dump.c
*
* BGP message dump logic.
*
* \copyright The DoubleFourteen Code Forge (C) All Rights Reserved
* \author Lorenzo Cogotti
*/
#include "bgpgrep_local.h"
#include "sys/con.h"
#include "sys/endian.h"
#include <assert.h>
#include <string.h>
// NOTE: TABLE_DUMPV2 RIBs may alter S.dropMsgFrame
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static void FixBgpAttributeTableForRib(Bgpattrtab tab, Boolean isRibv2)
{
// HACK ALERT:
//
// This is an innocent hack to speed up RIBv2 dumps on BGP messages
// that were already rebuilt (e.g. non-trivial filtering was necessary).
//
// The optimization is based on the fact that we know all offsets
// we've calculated inside the rebuilt BGP attribute list are valid up to
// the occurrence of MP_REACH_NLRI or MP_UNREACH_NLRI, whichever comes
// first. Moreover what we haven't found inside the BGP message attribute
// list isn't in the RIB either.
//
// NOTE: A LOT of RIBs also include the MP_UNREACH attribute,
// which is unfortunate. We clear the MP_UNREACH_NLRI attribute during
// filtering (to avoid printing false positives), but it still messes
// with the offsets of the subsequent attributes.
//
// NOTE: There is no chance to get BGP_ATTR_UNKNOWN inside the table,
// when BGP messages are rebuilt their offset table is filled up entirely.
// We don't need thread safety over Bgpattrtab, as bgpgrep is single-threaded.
Sint16 off = tab[bgp_attrTabIdx[BGP_ATTR_MP_UNREACH_NLRI]];
Uint16 maxoff = 0xffffu;
if (off != BGP_ATTR_NOTFOUND)
maxoff = (Uint16) off;
if (isRibv2) {
off = tab[bgp_attrTabIdx[BGP_ATTR_MP_REACH_NLRI]];
if (off != BGP_ATTR_NOTFOUND && maxoff > (Uint16) off)
maxoff = (Uint16) off;
}
if (maxoff == 0xffffu) // no MP_REACH or MP_UNREACH, table is perfectly ok
return;
// Reset any offset after maxoff
for (int i = 0; i < BGP_ATTRTAB_LEN; i++) {
off = tab[i];
if (off == BGP_ATTR_NOTFOUND)
continue;
if ((Uint16) off > maxoff)
tab[i] = BGP_ATTR_UNKNOWN;
}
}
static void OutputBgp4mp(const Mrthdr *hdr, Bgpattrtab tab)
{
S.lenientBgpErrors = TRUE;
S.outFmt->DumpBgp4mp(hdr, S.outf, S.outfOps, tab);
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S.lenientBgpErrors = FALSE;
}
void BgpgrepD_Bgp4mp(void)
{
const Mrthdr *hdr = MRT_HDR(&S.rec);
const Bgp4mphdr *bgp4mp = Bgp_GetBgp4mpHdr(&S.rec, NULL);
if (BGP4MP_ISSTATECHANGE(hdr->subtype)) {
OutputBgp4mp(hdr, NULL);
return;
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}
if (!BGP4MP_ISMESSAGE(hdr->subtype))
return; // don't care for anything else
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// NOTE: Optimizing BGP4MP to avoid message rebuild isn't worth the effort
// Setup for BGP4MP
S.peerAs = BGP4MP_GETPEERADDR(hdr->subtype, &S.peerAddr, bgp4mp);
S.timestampSecs = beswap32(hdr->timestamp);
S.timestampMicrosecs = 0;
if (hdr->subtype == MRT_BGP4MP_ET)
S.timestampMicrosecs = beswap32(((const Mrthdrex *) hdr)->microsecs);
// Dump MRT data
Bgp_UnwrapBgp4mp(&S.rec, &S.msg, /*flags=*/BGPF_UNOWNED);
if (Bgp_VmExec(&S.vm, &S.msg))
OutputBgp4mp(hdr, S.msg.table);
Bgp_ClearMsg(&S.msg);
}
static void OutputZebra(const Mrthdr *hdr, Bgpattrtab tab)
{
S.lenientBgpErrors = TRUE;
S.outFmt->DumpZebra(hdr, S.outf, S.outfOps, tab);
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S.lenientBgpErrors = FALSE;
}
void BgpgrepD_Zebra(void)
{
const Mrthdr *hdr = MRT_HDR(&S.rec);
const Zebrahdr *zebra = Bgp_GetZebraHdr(&S.rec, NULL);
if (hdr->subtype == ZEBRA_STATE_CHANGE) {
OutputZebra(hdr, NULL);
return;
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}
if (!ZEBRA_ISMESSAGE(hdr->subtype))
return; // don't care for anything else
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if (S.isTrivialFilter) {
// FAST PATH - avoid rebuilding original message
BGP_CLRATTRTAB(S.msg.table);
OutputZebra(hdr, S.msg.table);
return;
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}
// FILTERING PATH - Setup filter
S.peerAs = ASN16BIT(zebra->peerAs);
S.peerAddr.family = IP4;
S.peerAddr.v4 = zebra->peerAddr;
S.timestampSecs = beswap32(hdr->timestamp);
S.timestampMicrosecs = 0;
// Filter and dump BGP data
Bgp_UnwrapZebra(&S.rec, &S.msg, /*flags=*/0);
if (Bgp_VmExec(&S.vm, &S.msg))
OutputZebra(hdr, S.msg.table);
Bgp_ClearMsg(&S.msg);
}
static void OutputRibv2(const Mrthdr *hdr,
const Mrtpeerentv2 *peerent,
const Mrtribentv2 *ent,
Bgpattrtab tab)
{
S.lenientBgpErrors = TRUE;
S.outFmt->DumpRibv2(hdr, peerent, ent, S.outf, S.outfOps, tab);
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S.lenientBgpErrors = FALSE;
}
void BgpgrepD_TableDumpv2(void)
{
const Mrthdr *hdr = MRT_HDR(&S.rec);
if (hdr->subtype == TABLE_DUMPV2_PEER_INDEX_TABLE) {
// Store record as PEER_INDEX_TABLE
Bgp_ClearMrt(&S.peerIndex);
MRT_MOVEREC(&S.peerIndex, &S.rec);
S.hasPeerIndex = TRUE;
return;
}
if (!TABLE_DUMPV2_ISRIB(hdr->subtype))
return; // don't care for anything but RIBs
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// We may only dump record if we've got a PEER_INDEX_TABLE
if (!S.hasPeerIndex)
Bgpgrep_DropRecord("SKIPPING TABLE_DUMPV2 RECORD - No PEER_INDEX_TABLE found yet");
// Scan every entry inside RIBv2
const Mrtribentv2 *ent;
const Mrtribhdrv2 *ribhdr = Bgp_GetMrtRibHdrv2(&S.rec, NULL);
Mrtribiterv2 ribents;
Bgp_StartMrtRibEntriesv2(&ribents, &S.rec);
while ((ent = Bgp_NextRibEntryv2(&ribents)) != NULL) {
// If we get a corrupted entry, we must still scan what's next
if (setjmp_fast(S.dropMsgFrame))
continue;
// Fetch Peer entry
Uint16 idx = beswap16(ent->peerIndex);
const Mrtpeerentv2 *peerent = Bgp_GetMrtPeerByIndex(&S.peerIndex, idx);
if (S.isTrivialFilter) {
// FAST PATH - avoid BGP message rebuild
BGP_CLRATTRTAB(S.msg.table);
OutputRibv2(hdr, peerent, ent, S.msg.table);
continue;
}
// FILTERING PATH
Prefix pfx;
RIBV2_GETNLRI(hdr->subtype, &pfx, ribhdr, ent);
// Setup filter
S.peerAs = MRT_GETPEERADDR(&S.peerAddr, peerent);
S.timestampSecs = beswap32(ent->originatedTime);
S.timestampMicrosecs = 0;
// Execute filter and dump RIBv2s
const Bgpattrseg *tpa = RIBV2_GETATTRIBS(hdr->subtype, ent);
Bgp_RebuildMsgFromRib(&pfx, tpa, &S.msg, /*flags=*/BGPF_RIBV2|BGPF_CLEARUNREACH);
if (Bgp_VmExec(&S.vm, &S.msg)) {
FixBgpAttributeTableForRib(S.msg.table, /*isRibv2=*/TRUE);
OutputRibv2(hdr, peerent, ent, S.msg.table);
}
Bgp_ClearMsg(&S.msg);
}
}
static void OutputRib(const Mrthdr *hdr, const Mrtribent *ent, Bgpattrtab tab)
{
S.lenientBgpErrors = TRUE;
S.outFmt->DumpRib(hdr, ent, S.outf, S.outfOps, tab);
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S.lenientBgpErrors = FALSE;
}
void BgpgrepD_TableDump(void)
{
const Mrthdr *hdr = MRT_HDR(&S.rec);
const Mrtribent *ent = Bgp_GetMrtRibHdr(&S.rec);
if (S.isTrivialFilter) {
// FAST PATH - No need to rebuild BGP
BGP_CLRATTRTAB(S.msg.table);
OutputRib(hdr, ent, S.msg.table);
return;
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}
// FILTERING PATH - Setup VM for TABLE_DUMP
S.peerAs = RIB_GETPEERADDR(hdr->subtype, &S.peerAddr, ent);
S.timestampSecs = beswap32(RIB_GETORIGINATED(hdr->subtype, ent));
S.timestampMicrosecs = 0;
// Rebuild message and execute filter
Prefix pfx;
pfx.afi = hdr->subtype;
pfx.safi = SAFI_UNICAST;
pfx.isAddPath = FALSE;
pfx.pathId = 0; // unimportant
RIB_GETPFX(hdr->subtype, PLAINPFX(&pfx), ent);
const Bgpattrseg *tpa = RIB_GETATTRIBS(hdr->subtype, ent);
Bgp_RebuildMsgFromRib(&pfx, tpa, &S.msg, /*flags=*/BGPF_CLEARUNREACH);
if (Bgp_VmExec(&S.vm, &S.msg)) {
FixBgpAttributeTableForRib(S.msg.table, /*isRibv2=*/FALSE);
OutputRib(hdr, ent, S.msg.table);
}
Bgp_ClearMsg(&S.msg);
}