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ubgpsuite/lonetix/bgp/bgp.c

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// SPDX-License-Identifier: LGPL-3.0-or-later
/**
* \file bgp/bgp.c
*
* BGP message decoding.
*
* \copyright The DoubleFourteen Code Forge (C) All Rights Reserved
* \author Lorenzo Cogotti
*/
#include "bgp/bgp_local.h"
#include "sys/sys_local.h"
#include "sys/dbg.h"
#include "sys/endian.h"
#include "sys/ip.h"
#include "sys/con.h"
#include "argv.h"
#include "numlib.h"
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static const Uint8 bgp_marker[] = {
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
};
STATIC_ASSERT(sizeof(bgp_marker) == BGP_MARKER_LEN, "Malformed 'bgp_marker'");
static THREAD_LOCAL BgpErrStat bgp_errs;
const char *Bgp_ErrorString(BgpRet code)
{
switch (code) {
case BGPEBADVM: return "Attempting operation on BGP VM under error state";
case BGPEVMNOPROG: return "Attempt to execute BGP VM with empty bytecode";
case BGPEVMBADCOMTCH: return "Bad COMMUNITY match expression";
case BGPEVMASMTCHESIZE: return "BGP VM AS_PATH match expression too complex";
case BGPEVMASNGRPLIM: return "BGP VM AS_PATH match expression group limit hit";
case BGPEVMBADASMTCH: return "Bad AS_PATH match expression";
case BGPEVMBADJMP: return "BGP VM jump instruction target is out of bounds";
case BGPEVMILL: return "Illegal instruction in BGP VM bytecode";
case BGPEVMOOM: return "BGP VM heap memory exhausted";
case BGPEVMBADENDBLK: return "Encountered ENDBLK with no corresponding BLK";
case BGPEVMUFLOW: return "BGP VM stack underflow";
case BGPEVMOFLOW: return "BGP VM stack overflow";
case BGPEVMBADFN: return "CALL instruction index is out of bounds";
case BGPEVMBADK: return "LOADK instruction index is out of bounds";
case BGPEVMMSGERR: return "Error encountered during BGP message access";
case BGPEVMBADOP: return "BGP VM instruction has invalid operand";
case BGPENOERR: return "No error";
case BGPEIO: return "Input/Output error";
case BGPEBADTYPE: return "Provided BGP message has inconsistent type";
case BGPENOADDPATH: return "Provided BGP message contains no ADD_PATH information";
case BGPEBADATTRTYPE: return "Provided BGP attribute has inconsistent type";
case BGPEBADMARKER: return "BGP message marker mismatch";
case BGPENOMEM: return "Memory allocation failure";
case BGPETRUNCMSG: return "Truncated BGP message";
case BGPEOVRSIZ: return "Oversized BGP message";
case BGPEBADOPENLEN: return "BGP OPEN message has inconsistent length";
case BGPEDUPNLRIATTR: return "Duplicate NLRI attribute detected inside UPDATE message";
case BGPEBADPFXWIDTH: return "Bad prefix width";
case BGPETRUNCPFX: return "Truncated prefix";
case BGPETRUNCATTR: return "Truncated BGP attribute";
case BGPEBADAGGR: return "Malformed AGGREGATOR attribute";
case BGPEBADAGGR4: return "Malformed AS4_AGGREGATOR attribute";
case BGPEAFIUNSUP: return "Unsupported Address Family Identifier";
case BGPESAFIUNSUP: return "Unsupported Subsequent Address Family Identifier";
case BGPEBADMRTTYPE: return "Provided MRT record has inconsistent type";
case BGPETRUNCMRT: return "Truncated MRT record";
case BGPEBADPEERIDXCNT: return "TABLE_DUMPV2 Peer Index Table record has incoherent peer entry count";
case BGPETRUNCPEERV2: return "Truncated peer entry in TABLE_DUMPV2 Peer Index Table record";
case BGPEBADRIBV2CNT: return "TABLE_DUMPV2 RIB record has incoherent RIB entry count";
case BGPETRUNCRIBV2: return "Truncated entry in TABLE_DUMPV2 RIB record";
case BGPEBADRIBV2MPREACH: return "TABLE_DUMPV2 RIB record contains an illegal MP_REACH attribute";
case BGPERIBNOMPREACH: return "IPv6 RIB entry lacks MP_REACH_NLRI attribute";
case BGPEBADPEERIDX: return "Peer entry index is out of bounds";
default: return "Unknown BGP error";
}
}
static NOINLINE NORETURN void Bgp_Quit(BgpRet code, Srcloc *loc, void *obj)
{
USED(obj);
loc->call_depth++; // include Bgp_Quit() itself
if (com_progName) {
Sys_Print(STDERR, com_progName);
Sys_Print(STDERR, ": ");
}
Sys_Print(STDERR, "Terminate called in response to an unrecoverable BGP error.\n\t");
if (loc) {
#ifndef NDEBUG
if (loc->filename && loc->line > 0) {
char buf[64];
Utoa(loc->line, buf);
Sys_Print(STDERR, "Error occurred in file ");
Sys_Print(STDERR, loc->filename);
Sys_Print(STDERR, ":");
Sys_Print(STDERR, buf);
Sys_Print(STDERR, "\n\t");
}
#endif
if (loc->func) {
Sys_Print(STDERR, "[");
Sys_Print(STDERR, loc->func);
Sys_Print(STDERR, "()]: ");
}
}
Sys_Print(STDERR, Bgp_ErrorString(code));
Sys_Print(STDERR, ".\n");
exit(EXIT_FAILURE);
}
Judgement _Bgp_SetErrStat(BgpRet code,
const char *filename,
const char *func,
unsigned long long line,
unsigned depth)
{
// Don't clobber error code on BGP message access error inside filtering VM
if (code != BGPEVMMSGERR)
bgp_errs.code = code;
if (code == BGPENOERR)
return OK; // usual case
void (*err_func)(BgpRet, Srcloc *, void *);
Srcloc loc;
err_func = bgp_errs.func;
if (err_func) {
loc.filename = filename;
loc.func = func;
loc.line = line;
loc.call_depth = depth + 1;
if (err_func == BGP_ERR_QUIT)
err_func = Bgp_Quit;
err_func(code, &loc, bgp_errs.obj);
}
return NG;
}
void Bgp_SetErrFunc(void (*func)(BgpRet, Srcloc *, void *),
void *arg)
{
bgp_errs.func = func;
bgp_errs.obj = arg;
}
BgpRet Bgp_GetErrStat(BgpErrStat *stat)
{
if (stat)
*stat = bgp_errs;
return bgp_errs.code;
}
Uint16 Bgp_CheckMsgHdr(const void *data,
size_t nbytes,
Boolean allowExtendedSize)
{
if (nbytes < BGP_HDRSIZ) {
Bgp_SetErrStat(BGPETRUNCMSG);
return 0;
}
const Bgphdr *hdr = (const Bgphdr *) data;
if (memcmp(hdr->marker, bgp_marker, BGP_MARKER_LEN) != 0) {
Bgp_SetErrStat(BGPEBADMARKER);
return 0;
}
Uint16 len = beswap16(hdr->len);
if (len < BGP_HDRSIZ) {
Bgp_SetErrStat(BGPETRUNCMSG);
return 0;
}
if (len > BGP_MSGSIZ && !allowExtendedSize) {
Bgp_SetErrStat(BGPEOVRSIZ);
return 0;
}
if (len > nbytes) {
Bgp_SetErrStat(BGPETRUNCMSG);
return 0;
}
return len;
}
Judgement Bgp_MsgFromBuf(Bgpmsg *msg,
const void *data,
size_t nbytes,
unsigned flags)
{
// Immediately initialize flags (mask away superflous ones)
msg->flags = flags & (BGPF_ADDPATH|BGPF_ASN32BIT|BGPF_EXMSG|BGPF_UNOWNED);
// Check header data for correctness
Uint16 len = Bgp_CheckMsgHdr(data, nbytes, BGP_ISEXMSG(msg->flags));
if (len == 0)
return NG; // error already set by Bgp_CheckHdr()
if (BGP_ISUNOWNED(msg->flags))
msg->buf = (Uint8 *) data; // don't copy data over
else {
// Copy over relevant data
const MemOps *memOps = BGP_MEMOPS(msg);
msg->buf = (Uint8 *) memOps->Alloc(msg->allocp, len, NULL);
if (!msg->buf)
return Bgp_SetErrStat(BGPENOMEM);
memcpy(msg->buf, data, len);
}
BGP_CLRATTRTAB(msg->table);
return Bgp_SetErrStat(BGPENOERR);
}
Judgement Bgp_ReadMsg(Bgpmsg *msg,
void *streamp,
const StmOps *ops,
unsigned flags)
{
// Immediately initialize flags (mask away superflous ones)
msg->flags = flags & (BGPF_ADDPATH|BGPF_ASN32BIT|BGPF_EXMSG|BGPF_UNOWNED);
Uint8 buf[BGP_HDRSIZ];
Sint64 n = ops->Read(streamp, buf, BGP_HDRSIZ);
if (n == 0) {
// precisely at end of stream, no error, just no more BGP messages
Bgp_SetErrStat(BGPENOERR);
return NG;
}
if (n < 0)
return Bgp_SetErrStat(BGPEIO);
if ((size_t) n != BGP_HDRSIZ)
return Bgp_SetErrStat(BGPEIO);
// Retrieve memory allocator
const MemOps *memOps = BGP_MEMOPS(msg);
// Check header and allocate message
Uint16 len = Bgp_CheckMsgHdr(buf, BGP_HDRSIZ, BGP_ISEXMSG(msg->flags));
if (len == 0)
return NG;
msg->buf = (Uint8 *) memOps->Alloc(msg->allocp, len, NULL);
if (!msg->buf)
return Bgp_SetErrStat(BGPENOMEM);
// Copy over the message
memcpy(msg->buf, buf, BGP_HDRSIZ);
len -= BGP_HDRSIZ;
n = ops->Read(streamp, msg->buf + BGP_HDRSIZ, len);
if (n < 0) {
Bgp_SetErrStat(BGPEIO);
goto fail;
}
if ((size_t) n != len) {
Bgp_SetErrStat(BGPEIO);
goto fail;
}
BGP_CLRATTRTAB(msg->table);
return Bgp_SetErrStat(BGPENOERR);
fail:
memOps->Free(msg->allocp, msg->buf);
return NG;
}
#define BGP_OPEN_MINSIZ (BGP_HDRSIZ + 1uLL + 2uLL + 2uLL + 4uLL + 1uLL)
Bgpopen *Bgp_GetMsgOpen(Bgpmsg *msg)
{
Bgphdr *hdr = BGP_HDR(msg);
if (hdr->type != BGP_OPEN) {
Bgp_SetErrStat(BGPEBADTYPE);
return NULL;
}
size_t len = beswap16(hdr->len);
if (len < BGP_OPEN_MINSIZ) {
Bgp_SetErrStat(BGPETRUNCMSG);
return NULL;
}
Bgpopen *open = (Bgpopen *) hdr;
size_t nbytes = BGP_OPEN_MINSIZ + open->parmsLen;
if (nbytes != len) {
Bgp_SetErrStat((nbytes > len) ? BGPETRUNCMSG : BGPEBADOPENLEN);
return NULL;
}
Bgp_SetErrStat(BGPENOERR);
return open;
}
#define BGP_UPDATE_MINSIZ (BGP_HDRSIZ + 2uLL + 2uLL)
Bgpupdate *Bgp_GetMsgUpdate(Bgpmsg *msg)
{
Bgphdr *hdr = BGP_HDR(msg);
if (hdr->type != BGP_UPDATE) {
Bgp_SetErrStat(BGPEBADTYPE);
return NULL;
}
Uint16 len = beswap16(hdr->len);
if (len < BGP_UPDATE_MINSIZ) {
Bgp_SetErrStat(BGPETRUNCMSG);
return NULL;
}
Bgp_SetErrStat(BGPENOERR);
return (Bgpupdate *) hdr;
}
static Boolean Bgp_SwitchMpIterator(Bgpmpiter *it)
{
if (!it->nextAttr)
return FALSE; // no additional attribute to iterate, we're done
// Switch iterator
const Bgpmpfam *family = Bgp_GetMpFamily(it->nextAttr); // sets error
if (!family)
return FALSE; // corrupted attribute
size_t nbytes;
void *routes = Bgp_GetMpRoutes(it->nextAttr, &nbytes);
if (!routes)
return FALSE; // corrupted message
// Begin subsequent iteration
Afi afi = family->afi;
Safi safi = family->safi;
if (Bgp_StartPrefixes(&it->rng, afi, safi, routes, nbytes, it->rng.isAddPath) != OK)
return FALSE; // shouldn't happen
// Switch complete, clear attribute and move on
it->nextAttr = NULL;
return TRUE;
}
Judgement Bgp_StartMsgWithdrawn(Prefixiter *it, Bgpmsg *msg)
{
Bgpupdate *update = Bgp_GetMsgUpdate(msg);
if (!update)
return NG;
Bgpwithdrawnseg *withdrawn = Bgp_GetUpdateWithdrawn(update);
if (!withdrawn)
return NG;
return Bgp_StartPrefixes(it, AFI_IP, SAFI_UNICAST,
withdrawn->nlri, beswap16(withdrawn->len),
BGP_ISADDPATH(msg->flags));
}
Judgement Bgp_StartAllMsgWithdrawn(Bgpmpiter *it, Bgpmsg *msg)
{
it->nextAttr = Bgp_GetMsgAttribute(msg, BGP_ATTR_MP_UNREACH_NLRI);
if (!it->nextAttr && Bgp_GetErrStat(NULL))
return NG;
return Bgp_StartMsgWithdrawn(&it->rng, msg);
}
void Bgp_InitMpWithdrawn(Bgpmpiter *it,
const Bgpwithdrawnseg *withdrawn,
const Bgpattr *mpUnreach,
Boolean isAddPath)
{
it->nextAttr = (Bgpattr *) mpUnreach;
Bgp_StartPrefixes(&it->rng,
AFI_IP, SAFI_UNICAST,
withdrawn->nlri, beswap16(withdrawn->len),
isAddPath);
}
void Bgp_InitMpNlri(Bgpmpiter *it,
const void *nlri,
size_t nbytes,
const Bgpattr *mpReach,
Boolean isAddPath)
{
it->nextAttr = (Bgpattr *) mpReach;
Bgp_StartPrefixes(&it->rng, AFI_IP, SAFI_UNICAST, nlri, nbytes, isAddPath);
}
Judgement Bgp_StartMsgNlri(Prefixiter *it, Bgpmsg *msg)
{
Bgpupdate *update = Bgp_GetMsgUpdate(msg);
if (!update)
return NG;
size_t nbytes;
void *nlri = Bgp_GetUpdateNlri(update, &nbytes);
if (!nlri)
return NG;
return Bgp_StartPrefixes(it, AFI_IP, SAFI_UNICAST,
nlri, nbytes,
BGP_ISADDPATH(msg->flags));
}
Judgement Bgp_StartAllMsgNlri(Bgpmpiter *it, Bgpmsg *msg)
{
it->nextAttr = Bgp_GetMsgAttribute(msg, BGP_ATTR_MP_REACH_NLRI);
if (!it->nextAttr && Bgp_GetErrStat(NULL))
return NG;
return Bgp_StartMsgNlri(&it->rng, msg);
}
Prefix *Bgp_NextMpPrefix(Bgpmpiter *it)
{
void *rawPfx;
do {
rawPfx = Bgp_NextPrefix(&it->rng); // sets error
if (!rawPfx) {
// Swap iterator if necessary and try again
if (Bgp_GetErrStat(NULL))
return NULL;
if (!Bgp_SwitchMpIterator(it))
return NULL;
}
} while (!rawPfx);
// Extended prefix info
Prefix *cur = &it->pfx;
cur->afi = it->rng.afi;
cur->safi = it->rng.safi;
if (it->rng.isAddPath) {
// ADD-PATH enabled prefix
const ApRawPrefix *pfx = (const ApRawPrefix *) rawPfx;
cur->isAddPath = TRUE;
cur->pathId = pfx->pathId;
cur->width = pfx->width;
memcpy(cur->bytes, pfx->bytes, PFXLEN(pfx->width));
} else {
// Regular prefix
const RawPrefix *pfx = (const RawPrefix *) rawPfx;
cur->isAddPath = FALSE;
cur->pathId = 0;
cur->width = pfx->width;
memcpy(cur->bytes, pfx->bytes, PFXLEN(pfx->width));
}
return cur;
}
#define BGP_NOTIFICATION_MINSIZ (BGP_HDRSIZ + 1uLL + 1uLL)
Bgpnotification *Bgp_GetNotification(Bgpmsg *msg)
{
Bgphdr *hdr = BGP_HDR(msg);
if (hdr->type != BGP_NOTIFICATION) {
Bgp_SetErrStat(BGPEBADTYPE);
return NULL;
}
Uint16 len = beswap16(hdr->len);
if (len < BGP_NOTIFICATION_MINSIZ) {
Bgp_SetErrStat(BGPETRUNCMSG);
return NULL;
}
Bgp_SetErrStat(BGPENOERR);
return (Bgpnotification *) hdr;
}
Bgpparmseg *Bgp_GetParmsFromMemory(const void *data, size_t size)
{
const size_t BGP_OPEN_PARMSOFF = BGP_OPEN_MINSIZ - BGP_HDRSIZ;
if (size < BGP_OPEN_PARMSOFF) {
Bgp_SetErrStat(BGPETRUNCMSG);
return NULL;
}
Bgpparmseg *parms = (Bgpparmseg *) ((Uint8 *) data + BGP_OPEN_PARMSOFF - 1);
size_t nbytes = BGP_OPEN_PARMSOFF + parms->len;
if (nbytes != size) {
Bgp_SetErrStat((nbytes > size) ? BGPETRUNCMSG : BGPEBADOPENLEN);
return NULL;
}
Bgp_SetErrStat(BGPENOERR);
return parms;
}
Bgpparmseg *Bgp_GetOpenParms(const Bgpopen *open)
{
assert(open->hdr.type == BGP_OPEN);
size_t len = beswap16(open->hdr.len) - BGP_HDRSIZ;
return Bgp_GetParmsFromMemory(&open->version, len);
}
Bgpwithdrawnseg *Bgp_GetWithdrawnFromMemory(const void *data, size_t size)
{
if (size < 2uLL) {
Bgp_SetErrStat(BGPETRUNCMSG);
return NULL;
}
Bgpwithdrawnseg *withdrawn = (Bgpwithdrawnseg *) data;
size -= 2;
if (size < beswap16(withdrawn->len) + 2uLL) { // also accounts for TPA length
Bgp_SetErrStat(BGPETRUNCMSG);
return NULL;
}
Bgp_SetErrStat(BGPENOERR);
return withdrawn;
}
Bgpwithdrawnseg *Bgp_GetUpdateWithdrawn(const Bgpupdate *msg)
{
assert(msg->hdr.type == BGP_UPDATE);
size_t len = beswap16(msg->hdr.len);
return Bgp_GetWithdrawnFromMemory(msg->data, len - BGP_HDRSIZ);
}
Bgpattrseg *Bgp_GetAttributesFromMemory(const void *data, size_t size)
{
Bgpwithdrawnseg *withdrawn = Bgp_GetWithdrawnFromMemory(data, size);
if (!withdrawn)
return NULL; // sets error
size_t withdrawnLen = beswap16(withdrawn->len);
Bgpattrseg *tpa = (Bgpattrseg *) &withdrawn->nlri[withdrawnLen];
size_t tpaLen = beswap16(tpa->len);
if (size < 2uLL + withdrawnLen + 2uLL + tpaLen) {
Bgp_SetErrStat(BGPETRUNCMSG);
return NULL;
}
return tpa; // error already cleared
}
Bgpattrseg *Bgp_GetUpdateAttributes(const Bgpupdate *msg)
{
assert(msg->hdr.type == BGP_UPDATE);
size_t len = beswap16(msg->hdr.len);
return Bgp_GetAttributesFromMemory(msg->data, len - BGP_HDRSIZ);
}
void *Bgp_GetNlriFromMemory(const void *nlri, size_t size, size_t *nbytes)
{
Bgpattrseg *tpa = Bgp_GetAttributesFromMemory(nlri, size);
if (!tpa)
return NULL; // error already set
size_t tpaLen = beswap16(tpa->len);
if (nbytes) {
size_t offset = &tpa->attrs[tpaLen] - (Uint8 *) nlri;
*nbytes = size - offset;
}
return &tpa->attrs[tpaLen];
}
void *Bgp_GetUpdateNlri(const Bgpupdate *msg, size_t *nbytes)
{
assert(msg->hdr.type == BGP_UPDATE);
size_t len = beswap16(msg->hdr.len);
return Bgp_GetNlriFromMemory(msg->data, len - BGP_HDRSIZ, nbytes);
}
void Bgp_ClearMsg(Bgpmsg *msg)
{
if (!BGP_ISUNOWNED(msg->flags))
BGP_MEMOPS(msg)->Free(msg->allocp, msg->buf);
msg->flags = 0;
msg->buf = NULL;
}
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