Internet on FIRE

/*

 *	BIRD -- Configuration Lexer

 *

 *	(c) 1998--2000 Martin Mares <mj@ucw.cz>

 *

 *	Can be freely distributed and used under the terms of the GNU GPL.

 */

/**

 * DOC: Lexical analyzer

 *

 * The lexical analyzer used for configuration files and CLI commands

 * is generated using the |flex| tool accompanied by a couple of

 * functions maintaining the hash tables containing information about

 * symbols and keywords.

 *

 * Each symbol is represented by a &symbol structure containing name

 * of the symbol, its lexical scope, symbol class (%SYM_PROTO for a name of a protocol,

 * %SYM_NUMBER for a numeric constant etc.) and class dependent data.

 * When an unknown symbol is encountered, it's automatically added to the

 * symbol table with class %SYM_VOID.

 *

 * The keyword tables are generated from the grammar templates

 * using the |gen_keywords.m4| script.

 */

%{

#undef REJECT     /* Avoid name clashes */

#include <errno.h>

#include <stdlib.h>

#include <stdarg.h>

#include "nest/bird.h"

#include "nest/route.h"

#include "filter/filter.h"

#include "conf/conf.h"

#include "conf/cf-parse.tab.h"

#include "lib/string.h"

struct keyword {

  byte *name;

  int value;

  struct keyword *next;

};

#include "conf/keywords.h"

#define KW_HASH_SIZE 64

static struct keyword *kw_hash[KW_HASH_SIZE];

static int kw_hash_inited;

#define SYM_HASH_SIZE 128

#define SYM_MAX_LEN 32

struct sym_scope {

  struct sym_scope *next;		/* Next on scope stack */

  struct symbol *name;			/* Name of this scope */

  int active;				/* Currently entered */

};

static struct sym_scope *conf_this_scope;

int conf_lino;

static int cf_hash(byte *c);

static struct symbol *cf_find_sym(byte *c, unsigned int h0);

linpool *cfg_mem;

int (*cf_read_hook)(byte *buf, unsigned int max);

#define YY_INPUT(buf,result,max) result = cf_read_hook(buf, max);

#define YY_NO_UNPUT

#define YY_FATAL_ERROR(msg) cf_error(msg)

%}

%option noyywrap

%x COMMENT CCOMM CLI

ALPHA [a-zA-Z_]

DIGIT [0-9]

XIGIT [0-9a-fA-F]

ALNUM [a-zA-Z_0-9]

WHITE [ \t]

%%

{DIGIT}+\.{DIGIT}+\.{DIGIT}+\.{DIGIT}+ {

#ifdef IPV6

  if (ipv4_pton_u32(yytext, &cf_lval.i32))

    return RTRID;

  cf_error("Invalid IPv4 address %s", yytext);

#else

  if (ip_pton(yytext, &cf_lval.a))

    return IPA;

  cf_error("Invalid IP address %s", yytext);

#endif

}

({XIGIT}*::|({XIGIT}*:){3,})({XIGIT}*|{DIGIT}+\.{DIGIT}+\.{DIGIT}+\.{DIGIT}+) {

#ifdef IPV6

  if (ip_pton(yytext, &cf_lval.a))

    return IPA;

  cf_error("Invalid IP address %s", yytext);

#else

  cf_error("This is an IPv4 router, therefore IPv6 addresses are not supported");

#endif

}

0x{DIGIT}+ {

  char *e;

  long int l;

  errno = 0;

  l = strtoul(yytext+2, &e, 16);

  if (e && *e || errno == ERANGE || (long int)(int) l != l)

    cf_error("Number out of range");

  cf_lval.i = l;

  return NUM;

}

{DIGIT}+ {

  char *e;

  long int l;

  errno = 0;

  l = strtoul(yytext, &e, 10);

  if (e && *e || errno == ERANGE || (long int)(int) l != l)

    cf_error("Number out of range");

  cf_lval.i = l;

  return NUM;

}

{ALPHA}{ALNUM}* {

  unsigned int h = cf_hash(yytext);

  struct keyword *k = kw_hash[h & (KW_HASH_SIZE-1)];

  while (k)

    {

      if (!strcmp(k->name, yytext))

	{

	  if (k->value > 0)

	    return k->value;

	  else

	    {

	      cf_lval.i = -k->value;

	      return ENUM;

	    }

	}

      k=k->next;

    }

  cf_lval.s = cf_find_sym(yytext, h);

  return SYM;

}

<CLI>(.|\n) {

  BEGIN(INITIAL);

  return CLI_MARKER;

}

[={}:;,.()+*/%<>~\[\]?!-] {

  return yytext[0];

}

["][^"\n]*["] {

  yytext[yyleng-1] = 0;

  cf_lval.t = cfg_strdup(yytext+1);

  return TEXT;

}

["][^"\n]*\n	cf_error("Unterminated string");

<INITIAL,COMMENT><<EOF>>	return END;

{WHITE}+

\n	conf_lino++;

#	BEGIN(COMMENT);

\/\*	BEGIN(CCOMM);

.	cf_error("Unknown character");

<COMMENT>\n {

  conf_lino++;

  BEGIN(INITIAL);

}

<COMMENT>.

<CCOMM>\*\/	BEGIN(INITIAL);

<CCOMM>\n	conf_lino++;

<CCOMM>\/\*	cf_error("Comment nesting not supported");

<CCOMM><<EOF>>	cf_error("Unterminated comment");

<CCOMM>.

\!\= return NEQ;

\<\= return LEQ;

\>\= return GEQ;

\&\& return AND;

\|\| return OR;

%%

static int

cf_hash(byte *c)

{

  unsigned int h = 13;

  while (*c)

    h = (h * 37) + *c++;

  return h;

}

static struct symbol *

cf_new_sym(byte *c, unsigned int h)

{

  struct symbol *s, **ht;

  int l;

  if (!new_config->sym_hash)

    new_config->sym_hash = cfg_allocz(SYM_HASH_SIZE * sizeof(struct keyword *));

  ht = new_config->sym_hash;

  l = strlen(c);

  if (l > SYM_MAX_LEN)

    cf_error("Symbol too long");

  s = cfg_alloc(sizeof(struct symbol) + l);

  s->next = ht[h];

  ht[h] = s;

  s->scope = conf_this_scope;

  s->class = SYM_VOID;

  s->def = NULL;

  s->aux = 0;

  strcpy(s->name, c);

  return s;

}

static struct symbol *

cf_find_sym(byte *c, unsigned int h0)

{

  unsigned int h = h0 & (SYM_HASH_SIZE-1);

  struct symbol *s, **ht;

  if (ht = new_config->sym_hash)

    {

      for(s = ht[h]; s; s=s->next)

	if (!strcmp(s->name, c) && s->scope->active)

	  return s;

    }

  if (new_config->sym_fallback)

    {

      /* We know only top-level scope is active */

      for(s = new_config->sym_fallback[h]; s; s=s->next)

	if (!strcmp(s->name, c) && s->scope->active)

	  return s;

    }

  return cf_new_sym(c, h);

}

/**

 * cf_find_symbol - find a symbol by name

 * @c: symbol name

 *

 * This functions searches the symbol table for a symbol of given

 * name. First it examines the current scope, then the second recent

 * one and so on until it either finds the symbol and returns a pointer

 * to its &symbol structure or reaches the end of the scope chain

 * and returns %NULL to signify no match.

 */

struct symbol *

cf_find_symbol(byte *c)

{

  return cf_find_sym(c, cf_hash(c));

}

struct symbol *

cf_default_name(char *template, int *counter)

{

  char buf[32];

  struct symbol *s;

  char *perc = strchr(template, '%');

  for(;;)

    {

      bsprintf(buf, template, ++(*counter));

      s = cf_find_sym(buf, cf_hash(buf));

      if (!s)

	break;

      if (s->class == SYM_VOID)

	return s;

      if (!perc)

	break;

    }

  cf_error("Unable to generate default name");

}

/**

 * cf_define_symbol - define meaning of a symbol

 * @sym: symbol to be defined

 * @type: symbol class to assign

 * @def: class dependent data

 *

 * Defines new meaning of a symbol. If the symbol is an undefined

 * one (%SYM_VOID), it's just re-defined to the new type. If it's defined

 * in different scope, a new symbol in current scope is created and the

 * meaning is assigned to it. If it's already defined in the current scope,

 * an error is reported via cf_error().

 *

 * Result: Pointer to the newly defined symbol. If we are in the top-level

 * scope, it's the same @sym as passed to the function.

 */

struct symbol *

cf_define_symbol(struct symbol *sym, int type, void *def)

{

  if (sym->class)

    {

      if (sym->scope == conf_this_scope)

	cf_error("Symbol already defined");

      sym = cf_new_sym(sym->name, cf_hash(sym->name) & (SYM_HASH_SIZE-1));

    }

  sym->class = type;

  sym->def = def;

  return sym;

}

static void

cf_lex_init_kh(void)

{

  struct keyword *k;

  for(k=keyword_list; k->name; k++)

    {

      unsigned h = cf_hash(k->name) & (KW_HASH_SIZE-1);

      k->next = kw_hash[h];

      kw_hash[h] = k;

    }

  kw_hash_inited = 1;

}

/**

 * cf_lex_init - initialize the lexer

 * @is_cli: true if we're going to parse CLI command, false for configuration

 *

 * cf_lex_init() initializes the lexical analyzer and prepares it for

 * parsing of a new input.

 */

void

cf_lex_init(int is_cli)

{

  if (!kw_hash_inited)

    cf_lex_init_kh();

  conf_lino = 1;

  yyrestart(NULL);

  if (is_cli)

    BEGIN(CLI);

  else

    BEGIN(INITIAL);

  conf_this_scope = cfg_allocz(sizeof(struct sym_scope));

  conf_this_scope->active = 1;

}

/**

 * cf_push_scope - enter new scope

 * @sym: symbol representing scope name

 *

 * If we want to enter a new scope to process declarations inside

 * a nested block, we can just call cf_push_scope() to push a new

 * scope onto the scope stack which will cause all new symbols to be

 * defined in this scope and all existing symbols to be sought for

 * in all scopes stored on the stack.

 */

void

cf_push_scope(struct symbol *sym)

{

  struct sym_scope *s = cfg_alloc(sizeof(struct sym_scope));

  s->next = conf_this_scope;

  conf_this_scope = s;

  s->active = 1;

  s->name = sym;

}

/**

 * cf_pop_scope - leave a scope

 *

 * cf_pop_scope() pops the topmost scope from the scope stack,

 * leaving all its symbols in the symbol table, but making them

 * invisible to the rest of the config.

 */

void

cf_pop_scope(void)

{

  conf_this_scope->active = 0;

  conf_this_scope = conf_this_scope->next;

  ASSERT(conf_this_scope);

}

struct symbol *

cf_walk_symbols(struct config *cf, struct symbol *sym, int *pos)

{

  for(;;)

    {

      if (!sym)

	{

	  if (*pos >= SYM_HASH_SIZE)

	    return NULL;

	  sym = cf->sym_hash[(*pos)++];

	}

      else

	sym = sym->next;

      if (sym && sym->scope->active)

	return sym;

    }

}

/**

 * cf_symbol_class_name - get name of a symbol class

 * @sym: symbol

 *

 * This function returns a string representing the class

 * of the given symbol.

 */

char *

cf_symbol_class_name(struct symbol *sym)

{

  switch (sym->class)

    {

    case SYM_VOID:

      return "undefined";

    case SYM_PROTO:

      return "protocol";

    case SYM_NUMBER:

      return "numeric constant";

    case SYM_FUNCTION:

      return "function";

    case SYM_FILTER:

      return "filter";

    case SYM_TABLE:

      return "routing table";

    case SYM_IPA:

      return "network address";

    default:

      return "unknown type";

    }

}

/**

 * DOC: Parser

 *

 * Both the configuration and CLI commands are analyzed using a syntax

 * driven parser generated by the |bison| tool from a grammar which

 * is constructed from information gathered from grammar snippets by

 * the |gen_parser.m4| script.

 *

 * Grammar snippets are files (usually with extension |.Y|) contributed

 * by various BIRD modules in order to provide information about syntax of their

 * configuration and their CLI commands. Each snipped consists of several

 * sections, each of them starting with a special keyword: |CF_HDR| for

 * a list of |#include| directives needed by the C code, |CF_DEFINES|

 * for a list of C declarations, |CF_DECLS| for |bison| declarations

 * including keyword definitions specified as |CF_KEYWORDS|, |CF_GRAMMAR|

 * for the grammar rules, |CF_CODE| for auxiliary C code and finally

 * |CF_END| at the end of the snippet.

 *

 * To create references between the snippets, it's possible to define

 * multi-part rules by utilizing the |CF_ADDTO| macro which adds a new

 * alternative to a multi-part rule.

 *

 * CLI commands are defined using a |CF_CLI| macro. Its parameters are:

 * the list of keywords determining the command, the list of parameters,

 * help text for the parameters and help text for the command.

 *

 * Values of |enum| filter types can be defined using |CF_ENUM| with

 * the following parameters: name of filter type, prefix common for all

 * literals of this type and names of all the possible values.

 */