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ubgpsuite/tools/bgpgrep/bgpgrep_compile.c

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// SPDX-License-Identifier: GPL-3.0-or-later
/**
* \file bgpgrep_compile.c
*
* Filtering expression predicate compilation to VM bytecode.
*
* \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 "sys/fs.h"
#include "sys/sys.h"
#include "lexer.h"
#include "numlib.h"
#include "strlib.h"
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#define MAXCODE 8192
#define MAXLEAFLEN 8
// Expression types, in order of ascending precedence
typedef enum {
OP_NONE, // no operation
OP_OR, // -or, -o
OP_AND, // -and, -a (implicit when 2 consecutive expressions are found)
OP_NOT, // -not, !
OP_LEAF // instruction block, leaf node
} Expropc;
typedef Uint16 Expridx;
typedef struct {
Expropc opc;
union {
// Expression node
struct {
Expridx l, r; // left-right subnodes
} n;
// Expression leaf
struct {
Uint8 nc;
Bgpvmbytec c[MAXLEAFLEN];
} leaf;
};
} Exprop;
typedef struct {
// Argument list
int argc;
int argidx;
char **argv;
char *curterm;
Sint32 loopsFn;
Sint32 peerMatchFn;
Sint32 timestampCmpFn;
Uint16 ncode;
Boolean8 wasImplicitAnd;
Exprop code[MAXCODE];
} BgpgrepC;
static BgpgrepC C;
static Expridx BgpgrepC_ParseExpression(void); // Forward decl
static char *BgpgrepC_LastToken(void)
{
assert(C.argidx > 0);
return C.argv[C.argidx - 1];
}
static void BgpgrepC_UngetToken(void)
{
assert(C.argidx > 0 || C.wasImplicitAnd);
if (C.wasImplicitAnd)
C.wasImplicitAnd = FALSE;
else
C.argidx--;
}
static Boolean IsEndOfParse(void)
{
return C.argidx == C.argc && !C.wasImplicitAnd;
}
char *BgpgrepC_GetToken(void)
{
C.wasImplicitAnd = FALSE;
return (C.argidx < C.argc) ? C.argv[C.argidx++] : NULL;
}
char *BgpgrepC_CurTerm(void)
{
return C.curterm;
}
char *BgpgrepC_ExpectAnyToken(void)
{
if (C.argidx >= C.argc)
Bgpgrep_Fatal("Unexpected match expression end after '%s'", BgpgrepC_LastToken());
return C.argv[C.argidx++];
}
char *BgpgrepC_ExpectToken(const char *what)
{
if (C.argidx >= C.argc)
Bgpgrep_Fatal("Unexpected match expression end after '%s', while expecting '%s'", BgpgrepC_LastToken(), what);
char *tok = C.argv[C.argidx++];
if (strcmp(tok, what) != 0)
Bgpgrep_Fatal("Unexpected token '%s' while expecting '%s'", tok, what);
return tok;
}
static Expridx PushOp(Expridx l, Expropc opc, Expridx r)
{
if (C.ncode >= MAXCODE)
Bgpgrep_Fatal("At '%s': Expression operations limit reached, please simplify the input expression", BgpgrepC_LastToken());
Expridx idx = C.ncode++;
Exprop *op = &C.code[idx];
op->opc = opc;
op->n.l = l;
op->n.r = r;
return idx;
}
static Expridx PushLeaf(const Bgpvmbytec *c, size_t n)
{
assert(n <= MAXLEAFLEN);
if (C.ncode >= MAXCODE)
Bgpgrep_Fatal("At '%s': Expression operations limit reached, please simplify the input expression", BgpgrepC_LastToken());
Expridx idx = C.ncode++;
Exprop *op = &C.code[idx];
op->opc = OP_LEAF;
op->leaf.nc = n;
memcpy(op->leaf.c, c, n * sizeof(*op->leaf.c));
return idx;
}
static BgpType ParseBgpType(void)
{
const char *tok = BgpgrepC_ExpectAnyToken();
if (Df_stricmp(tok, "OPEN") == 0)
return BGP_OPEN;
if (Df_stricmp(tok, "UPDATE") == 0)
return BGP_UPDATE;
if (Df_stricmp(tok, "KEEPALIVE") == 0)
return BGP_KEEPALIVE;
if (Df_stricmp(tok, "NOTIFICATION") == 0)
return BGP_NOTIFICATION;
if (Df_stricmp(tok, "ROUTE_REFRESH") == 0)
return BGP_ROUTE_REFRESH;
if (Df_stricmp(tok, "CLOSE") == 0)
return BGP_CLOSE;
Bgpgrep_Fatal("-type: Unknown BGP message type: %s", tok);
}
static BgpAttrCode ParseBgpAttr(void)
{
const char *tok = BgpgrepC_ExpectAnyToken();
if (Df_stricmp(tok, "ORIGIN") == 0) return BGP_ATTR_ORIGIN;
if (Df_stricmp(tok, "AS_PATH") == 0) return BGP_ATTR_AS_PATH;
if (Df_stricmp(tok, "NEXT_HOP") == 0) return BGP_ATTR_NEXT_HOP;
if (Df_stricmp(tok, "MULTI_EXIT_DISC") == 0) return BGP_ATTR_MULTI_EXIT_DISC;
if (Df_stricmp(tok, "LOCAL_PREFI") == 0) return BGP_ATTR_LOCAL_PREF;
if (Df_stricmp(tok, "ATOMIC_AGGREGATE") == 0) return BGP_ATTR_ATOMIC_AGGREGATE;
if (Df_stricmp(tok, "AGGREGATOR") == 0) return BGP_ATTR_AGGREGATOR;
if (Df_stricmp(tok, "COMMUNITY") == 0) return BGP_ATTR_COMMUNITY;
if (Df_stricmp(tok, "ORIGINATOR_ID") == 0) return BGP_ATTR_ORIGINATOR_ID;
if (Df_stricmp(tok, "CLUSTER_LIST") == 0) return BGP_ATTR_CLUSTER_LIST;
if (Df_stricmp(tok, "DPA") == 0) return BGP_ATTR_DPA;
if (Df_stricmp(tok, "ADVERTISER") == 0) return BGP_ATTR_ADVERTISER;
if (Df_stricmp(tok, "RCID_PATH_CLUSTER_ID") == 0) return BGP_ATTR_RCID_PATH_CLUSTER_ID;
if (Df_stricmp(tok, "MP_REACH_NLRI") == 0) return BGP_ATTR_MP_REACH_NLRI;
if (Df_stricmp(tok, "MP_UNREACH_NLRI") == 0) return BGP_ATTR_MP_UNREACH_NLRI;
if (Df_stricmp(tok, "EXTENDED_COMMUNITY") == 0) return BGP_ATTR_EXTENDED_COMMUNITY;
if (Df_stricmp(tok, "AS4_PATH") == 0) return BGP_ATTR_AS4_PATH;
if (Df_stricmp(tok, "AS4_AGGREGATOR") == 0) return BGP_ATTR_AS4_AGGREGATOR;
if (Df_stricmp(tok, "SAFI_SSA") == 0) return BGP_ATTR_SAFI_SSA;
if (Df_stricmp(tok, "CONNECTOR") == 0) return BGP_ATTR_CONNECTOR;
if (Df_stricmp(tok, "AS_PATHLIMIT") == 0) return BGP_ATTR_AS_PATHLIMIT;
if (Df_stricmp(tok, "PMSI_TUNNEL") == 0) return BGP_ATTR_PMSI_TUNNEL;
if (Df_stricmp(tok, "TUNNEL_ENCAPSULATION") == 0) return BGP_ATTR_TUNNEL_ENCAPSULATION;
if (Df_stricmp(tok, "TRAFFIC_ENGINEERING") == 0) return BGP_ATTR_TRAFFIC_ENGINEERING;
if (Df_stricmp(tok, "IPV6_ADDRESS_SPECIFIC_EXTENDED_COMMUNITY") == 0) return BGP_ATTR_IPV6_ADDRESS_SPECIFIC_EXTENDED_COMMUNITY;
if (Df_stricmp(tok, "AIGP") == 0) return BGP_ATTR_AIGP;
if (Df_stricmp(tok, "PE_DISTINGUISHER_LABELS") == 0) return BGP_ATTR_PE_DISTINGUISHER_LABELS;
if (Df_stricmp(tok, "ENTROPY_LEVEL_CAPABILITY") == 0) return BGP_ATTR_ENTROPY_LEVEL_CAPABILITY;
if (Df_stricmp(tok, "LS") == 0) return BGP_ATTR_LS;
if (Df_stricmp(tok, "LARGE_COMMUNITY") == 0) return BGP_ATTR_LARGE_COMMUNITY;
if (Df_stricmp(tok, "BGPSEC_PATH") == 0) return BGP_ATTR_BGPSEC_PATH;
if (Df_stricmp(tok, "COMMUNITY_CONTAINER") == 0) return BGP_ATTR_COMMUNITY_CONTAINER;
if (Df_stricmp(tok, "PREFIX_SID") == 0) return BGP_ATTR_PREFIX_SID;
if (Df_stricmp(tok, "SET") == 0) return BGP_ATTR_SET;
char *p;
NumConvRet ret;
unsigned code = Atou(tok, &p, /*base=*/0, &ret);
if (ret != NCVENOERR || code > 0xff || *p != '\0')
Bgpgrep_Fatal("-attr: Bad attribute '%s'", tok);
return code;
}
static void AddPrefixListToTrie(Triepair *dest,
const Pfxlist *list,
NetpfxType type)
{
memset(dest, 0, sizeof(*dest));
for (const Pfxnode *n = list->head[type]; n; n = n->next[type]) {
switch (n->pfx.afi) {
case AFI_IP:
if (!dest->v4) dest->v4 = BgpgrepC_NewTrie(AFI_IP);
if (!Pat_Insert(&dest->v4->trie, PLAINPFX(&n->pfx)))
Sys_OutOfMemory();
break;
case AFI_IP6:
if (!dest->v6) dest->v6 = BgpgrepC_NewTrie(AFI_IP6);
if (!Pat_Insert(&dest->v6->trie, PLAINPFX(&n->pfx)))
Sys_OutOfMemory();
break;
default: UNREACHABLE; break;
}
}
}
static Expridx ParsePrefixOp(Bgpvmopc opc)
{
Pfxlist list;
Bgpvmbytec c[MAXLEAFLEN];
size_t nc = 0;
Triepair t;
BgpgrepC_ParsePrefixList(&list);
if (list.isEmpty)
c[nc++] = BGP_VMOP(BGP_VMOP_LOADU, 0); // empty list = always FAIL
if (list.head[WITHDRAWN]) {
AddPrefixListToTrie(&t, &list, WITHDRAWN);
c[nc++] = t.v4 ? BGP_VMOP(BGP_VMOP_LOADK, t.v4->kidx) : BGP_VMOP_LOADN;
c[nc++] = t.v6 ? BGP_VMOP(BGP_VMOP_LOADK, t.v6->kidx) : BGP_VMOP_LOADN;
c[nc++] = BGP_VMOP(opc, BGP_VMOPA_ALL_WITHDRAWN);
}
if (list.head[ANNOUNCE]) {
if (!list.areListsMatching) AddPrefixListToTrie(&t, &list, ANNOUNCE);
if (list.head[WITHDRAWN]) c[nc++] = BGP_VMOP(BGP_VMOP_JNZ, 3);
c[nc++] = t.v4 ? BGP_VMOP(BGP_VMOP_LOADK, t.v4->kidx) : BGP_VMOP_LOADN;
c[nc++] = t.v6 ? BGP_VMOP(BGP_VMOP_LOADK, t.v6->kidx) : BGP_VMOP_LOADN;
c[nc++] = BGP_VMOP(opc, BGP_VMOPA_ALL_NLRI);
}
Expridx idx = PushLeaf(c, nc);
BgpgrepC_FreePrefixList(&list);
return idx;
}
static Expridx GetTerm(void)
{
Bgpvmbytec c[MAXLEAFLEN];
size_t n = 0;
C.curterm = BgpgrepC_ExpectAnyToken();
if (strcmp(C.curterm, "(") == 0) {
Expridx e = BgpgrepC_ParseExpression();
BgpgrepC_ExpectToken(")");
return e;
} else if (strcmp(C.curterm, "!") == 0 || strcmp(C.curterm, "-not") == 0) {
return PushOp(0, OP_NOT, GetTerm());
} else if (strcmp(C.curterm, "-type") == 0) {
BgpType type = ParseBgpType();
c[n++] = BGP_VMOP(BGP_VMOP_CHKT, type);
return PushLeaf(c, n);
} else if (strcmp(C.curterm, "-attr") == 0) {
BgpAttrCode code = ParseBgpAttr();
c[n++] = BGP_VMOP(BGP_VMOP_CHKA, code);
return PushLeaf(c, n);
} else if (strcmp(C.curterm, "-aspath") == 0) {
Sint32 kidx = BgpgrepC_BakeAsRegexp();
c[n++] = BGP_VMOP(BGP_VMOP_LOADK, kidx);
c[n++] = BGP_VMOP_FASMTC;
return PushLeaf(c, n);
} else if (strcmp(C.curterm, "-peer") == 0) {
Sint32 kidx = BgpgrepC_ParsePeerExpression();
if (kidx >= 0) {
// Non-empty list, compile to a call
c[n++] = BGP_VMOP(BGP_VMOP_LOADK, kidx);
c[n++] = BGP_VMOP(BGP_VMOP_CALL, C.peerMatchFn);
} else {
// Empty list, always fails
c[n++] = BGP_VMOP(BGP_VMOP_LOADU, FALSE);
}
return PushLeaf(c, n);
} else if (strcmp(C.curterm, "-loops") == 0) {
c[n++] = BGP_VMOP(BGP_VMOP_CALL, C.loopsFn);
return PushLeaf(c, n);
} else if (strcmp(C.curterm, "-exact") == 0) {
return ParsePrefixOp(BGP_VMOP_EXCT);
} else if (strcmp(C.curterm, "-supernet") == 0) {
return ParsePrefixOp(BGP_VMOP_SUPN);
} else if (strcmp(C.curterm, "-subnet") == 0) {
return ParsePrefixOp(BGP_VMOP_SUBN);
} else if (strcmp(C.curterm, "-related") == 0) {
return ParsePrefixOp(BGP_VMOP_RELT);
} else if (strcmp(C.curterm, "-timestamp") == 0) {
Sint32 kidx = BgpgrepC_ParseTimestampExpression();
c[n++] = BGP_VMOP(BGP_VMOP_LOADK, kidx);
c[n++] = BGP_VMOP(BGP_VMOP_CALL, C.timestampCmpFn);
return PushLeaf(c, n);
} else if (strcmp(C.curterm, "-communities") == 0) {
Sint32 kidx = BgpgrepC_ParseCommunity(BGP_VMOPT_ASSUME_COMTCH);
if (kidx >= 0) {
// Non-empty list, emit COMTCH
c[n++] = BGP_VMOP(BGP_VMOP_LOADK, kidx);
c[n++] = BGP_VMOP_COMTCH;
} else {
// Empty community always fails
c[n++] = BGP_VMOP(BGP_VMOP_LOADU, FALSE);
}
return PushLeaf(c, n);
} else if (strcmp(C.curterm, "-all-communities") == 0) {
Sint32 kidx = BgpgrepC_ParseCommunity(BGP_VMOPT_ASSUME_ACOMTC);
if (kidx >= 0) {
// Non-empt list, emit ACOMTC
c[n++] = BGP_VMOP(BGP_VMOP_LOADK, kidx);
c[n++] = BGP_VMOP_ACOMTC;
} else {
// Empty list always succeeds
c[n++] = BGP_VMOP(BGP_VMOP_LOADU, TRUE);
}
return PushLeaf(c, n);
} else {
Bgpgrep_Fatal("Invalid expression term '%s'", C.curterm);
return 0;
}
}
static Expropc GetOp(void)
{
const char *tok = BgpgrepC_GetToken();
Expropc opc = OP_NONE;
if (tok) {
if (strcmp(tok, "-and") == 0 || strcmp(tok, "-a") == 0) {
opc = OP_AND;
} else if (strcmp(tok, "-or") == 0 || strcmp(tok, "-o") == 0) {
opc = OP_OR;
} else {
// Implicitly assume AND with anything else that follows
BgpgrepC_UngetToken();
// Closing ) appear due to expression grouping
// e.g. ( -type ORIGIN -or -type AGGREGATOR )
//
// In this case we should return OP_NONE to signal
// expression end, propagating out of ParseExpression()
if (strcmp(tok, ")") != 0) {
C.wasImplicitAnd = TRUE;
opc = OP_AND;
}
}
}
return opc;
}
static Expridx BgpgrepC_ParseExpressionRecurse(Expridx l, int prio)
{
while (TRUE) {
Expropc opc = GetOp();
if (opc == OP_NONE)
break;
if ((int) opc < prio) {
BgpgrepC_UngetToken();
break;
}
Expridx r = GetTerm();
while (TRUE) {
Expropc nextOpc = GetOp();
if (nextOpc == OP_NONE)
break;
BgpgrepC_UngetToken();
if (nextOpc <= opc)
break;
r = BgpgrepC_ParseExpressionRecurse(r, nextOpc);
}
l = PushOp(l, opc, r);
}
return l;
}
static Expridx BgpgrepC_ParseExpression(void)
{
Expridx l = GetTerm();
return BgpgrepC_ParseExpressionRecurse(l, OP_NONE);
}
static Boolean IsNestedBlock(Expropc outer, Expropc inner)
{
assert(inner == OP_AND || inner == OP_OR);
return outer != OP_NONE && inner != outer;
}
static Expropc BgpgrepC_CompileRecurse(Expridx idx, Expropc opc)
{
Boolean nestedBlock;
const Exprop *op = &C.code[idx];
switch (op->opc) {
case OP_AND:
nestedBlock = IsNestedBlock(opc, op->opc);
if (nestedBlock)
Bgp_VmEmit(&S.vm, BGP_VMOP_BLK);
BgpgrepC_CompileRecurse(op->n.l, op->opc);
if (C.code[op->n.l].opc != OP_AND) {
Bgp_VmEmit(&S.vm, BGP_VMOP_NOT);
Bgp_VmEmit(&S.vm, BGP_VMOP_CFAIL);
}
BgpgrepC_CompileRecurse(op->n.r, op->opc);
if (C.code[op->n.r].opc != OP_AND) {
Bgp_VmEmit(&S.vm, BGP_VMOP_NOT);
Bgp_VmEmit(&S.vm, BGP_VMOP_CFAIL);
}
if (nestedBlock) {
Bgp_VmEmit(&S.vm, BGP_VMOP(BGP_VMOP_LOADU, TRUE));
Bgp_VmEmit(&S.vm, BGP_VMOP_CPASS);
Bgp_VmEmit(&S.vm, BGP_VMOP_ENDBLK);
}
break;
case OP_OR:
nestedBlock = IsNestedBlock(opc, op->opc);
if (nestedBlock)
Bgp_VmEmit(&S.vm, BGP_VMOP_BLK);
BgpgrepC_CompileRecurse(op->n.l, op->opc);
if (C.code[op->n.l].opc != OP_OR)
Bgp_VmEmit(&S.vm, BGP_VMOP_CPASS);
BgpgrepC_CompileRecurse(op->n.r, op->opc);
if (C.code[op->n.r].opc != OP_OR)
Bgp_VmEmit(&S.vm, BGP_VMOP_CPASS);
if (nestedBlock) {
Bgp_VmEmit(&S.vm, BGP_VMOP(BGP_VMOP_LOADU, TRUE));
Bgp_VmEmit(&S.vm, BGP_VMOP_CFAIL);
Bgp_VmEmit(&S.vm, BGP_VMOP_ENDBLK);
}
break;
case OP_NOT:
BgpgrepC_CompileRecurse(op->n.r, OP_NOT);
Bgp_VmEmit(&S.vm, BGP_VMOP_NOT);
break;
case OP_LEAF:
for (unsigned i = 0; i < op->leaf.nc; i++)
Bgp_VmEmit(&S.vm, op->leaf.c[i]);
break;
default: UNREACHABLE; break;
}
return op->opc;
}
static void BgpgrepC_Compile(Expridx startIdx)
{
Expropc opc = BgpgrepC_CompileRecurse(startIdx, OP_NONE);
// Compile the very last result
switch (opc) {
case OP_OR:
Bgp_VmEmit(&S.vm, BGP_VMOP(BGP_VMOP_LOADU, TRUE));
Bgp_VmEmit(&S.vm, BGP_VMOP_CFAIL);
break;
case OP_AND:
Bgp_VmEmit(&S.vm, BGP_VMOP(BGP_VMOP_LOADU, TRUE));
Bgp_VmEmit(&S.vm, BGP_VMOP_CPASS);
break;
case OP_NOT:
case OP_LEAF:
Bgp_VmEmit(&S.vm, BGP_VMOP_CPASS);
Bgp_VmEmit(&S.vm, BGP_VMOP(BGP_VMOP_LOADU, TRUE));
Bgp_VmEmit(&S.vm, BGP_VMOP_CFAIL);
break;
default: UNREACHABLE; break;
}
}
static Boolean IsLoadNz(Bgpvmbytec bytec)
{
switch (BGP_VMOPC(bytec)) {
case BGP_VMOP_LOAD:
case BGP_VMOP_LOADU: return BGP_VMOPARG(bytec) != 0;
default: return FALSE;
}
}
static Boolean IsLoadZ(Bgpvmbytec bytec)
{
switch (BGP_VMOPC(bytec)) {
case BGP_VMOP_LOAD:
case BGP_VMOP_LOADU: return BGP_VMOPARG(bytec) == 0;
default: return FALSE;
}
}
static void BgpgrepC_Optimize(void)
{
Uint32 i, j, n;
// Perform trivial peephole optimization
Uint32 wi[4];
Bgpvmbytec w[4];
Boolean changed;
i = 0;
while (i < S.vm.progLen) { // NOTE: don't care for END
if (S.vm.prog[i] == BGP_VMOP_NOP) {
// Skip initial NOPs
i++;
continue;
}
changed = FALSE;
// Fill peephole window
for (j = 0, n = 0; n < ARRAY_SIZE(w); j++) {
if (i + j >= S.vm.progLen) // NOTE: don't care for END
break;
if (S.vm.prog[i+j] == BGP_VMOP_NOP)
continue; // do not place any NOP inside window
wi[n] = i+j;
w[n] = S.vm.prog[i+j];
n++;
}
// Trivial redundant operation elimination
for (j = 1; j < n; j++) {
// NOT-NOT = NOP
if (w[j] == BGP_VMOP_NOT && w[j-1] == BGP_VMOP_NOT) {
w[j-1] = w[j] = BGP_VMOP_NOP;
changed = TRUE;
continue;
}
// LOADU 0-NOT = LOADU 1
if (IsLoadZ(w[j-1]) && w[j] == BGP_VMOP_NOT) {
w[j-1] = BGP_VMOP_NOP;
w[j] = BGP_VMOP(BGP_VMOP_LOADU, 1);
changed = TRUE;
continue;
}
// LOADU 1-NOT = LOADU 0
if (IsLoadNz(w[j-1]) && w[j] == BGP_VMOP_NOT) {
w[j-1] = BGP_VMOP_NOP;
w[j] = BGP_VMOP(BGP_VMOP_LOADU, 0);
changed = TRUE;
continue;
}
}
if (n == 4) {
// Simplify common CFAIL and CPASS chains introduced by AND/OR blocks
static const Bgpvmbytec ncfncp[] = {
BGP_VMOP_NOT,
BGP_VMOP_CFAIL,
BGP_VMOP(BGP_VMOP_LOADU, TRUE),
BGP_VMOP_CPASS
};
static const Bgpvmbytec ncpncf[] = {
BGP_VMOP_NOT,
BGP_VMOP_CPASS,
BGP_VMOP(BGP_VMOP_LOADU, TRUE),
BGP_VMOP_CFAIL
};
if (memcmp(w, ncfncp, sizeof(ncfncp)) == 0) {
// Move CPASS up
w[0] = BGP_VMOP_NOP;
w[1] = BGP_VMOP_CPASS;
w[2] = BGP_VMOP(BGP_VMOP_LOADU, TRUE);
w[3] = BGP_VMOP_CFAIL;
changed = TRUE;
} else if (memcmp(w, ncpncf, sizeof(ncpncf)) == 0) {
// Move CFAIL up
w[0] = BGP_VMOP_NOP;
w[1] = BGP_VMOP_CFAIL;
w[2] = BGP_VMOP(BGP_VMOP_LOADU, TRUE);
w[3] = BGP_VMOP_CPASS;
changed = TRUE;
}
}
if (changed) {
// Update VM bytecode
for (j = 0; j < n; j++)
S.vm.prog[wi[j]] = w[j];
continue; // another round of peephole optimization
}
// No optimization, slide window
i++;
}
// Eliminate NOPs
for (i = 0, j = 0; i <= S.vm.progLen; i++) {
if (S.vm.prog[i] != BGP_VMOP_NOP)
S.vm.prog[j++] = S.vm.prog[i];
}
S.vm.progLen = j-1;
assert(S.vm.prog[S.vm.progLen] == BGP_VMOP_END);
}
Trielist *BgpgrepC_NewTrie(Afi afi)
{
Trielist *t = (Trielist *) malloc(sizeof(*t));
if (!t)
Sys_OutOfMemory();
memset(&t->trie, 0, sizeof(t->trie));
t->trie.afi = afi;
t->kidx = BGP_VMSETKA(&S.vm, Bgp_VmNewk(&S.vm), &t->trie);
if (t->kidx == -1)
Bgpgrep_Fatal("BGP filter variables limit hit");
t->next = S.trieList;
S.trieList = t;
return t;
}
void Bgpgrep_CompileVmProgram(int argc, char **argv)
{
// Initial compiler setup
C.argc = argc;
C.argidx = 0;
C.argv = argv;
C.ncode = 0;
C.wasImplicitAnd = FALSE;
C.loopsFn = BGP_VMSETFN(&S.vm,
Bgp_VmNewFn(&S.vm),
BgpgrepF_FindAsLoops);
C.peerMatchFn = BGP_VMSETFN(&S.vm,
Bgp_VmNewFn(&S.vm),
BgpgrepF_PeerAddrMatch);
C.timestampCmpFn = BGP_VMSETFN(&S.vm,
Bgp_VmNewFn(&S.vm),
BgpgrepF_TimestampCompare);
assert(C.loopsFn >= 0);
assert(C.peerMatchFn >= 0);
assert(C.timestampCmpFn >= 0);
// Actual compilation
if (C.argc > 0) {
Expridx r = BgpgrepC_ParseExpression();
// Make sure we've consumed the whole expression
if (!IsEndOfParse()) {
const char *last = BgpgrepC_LastToken();
const char *tok = BgpgrepC_GetToken();
if (tok)
Bgpgrep_Fatal("Unexpected '%s' after '%s'", tok, last);
else // should never happen but still...
Bgpgrep_Fatal("Unexpected match expression end after '%s'", last);
}
// Convert to bytecode
BgpgrepC_Compile(r);
BgpgrepC_Optimize();
} else {
// Trivial filter
Bgp_VmEmit(&S.vm, BGP_VMOP(BGP_VMOP_LOADU, TRUE));
Bgp_VmEmit(&S.vm, BGP_VMOP_CPASS);
S.isTrivialFilter = TRUE;
}
if (S.dumpBytecode)
Bgp_VmDumpProgram(&S.vm, STM_CONHN(STDERR), Stm_ConOps);
}
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