bird/conf/cf-lex.l
2016-05-12 18:03:23 +02:00

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16 KiB
Text

/*
* 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_CONSTANT for a 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 <unistd.h>
#include <libgen.h>
#include <glob.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/stat.h>
#define PARSER 1
#include "nest/bird.h"
#include "nest/route.h"
#include "nest/protocol.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
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;
static int cf_hash(byte *c);
static inline struct symbol * cf_get_sym(byte *c, uint h0);
linpool *cfg_mem;
int (*cf_read_hook)(byte *buf, unsigned int max, int fd);
struct include_file_stack *ifs;
static struct include_file_stack *ifs_head;
#define MAX_INCLUDE_DEPTH 8
#define YY_INPUT(buf,result,max) result = cf_read_hook(buf, max, ifs->fd);
#define YY_NO_UNPUT
#define YY_FATAL_ERROR(msg) cf_error(msg)
static void cf_include(char *arg, int alen);
static int check_eof(void);
%}
%option noyywrap
%option noinput
%option nounput
%option noreject
%x COMMENT CCOMM CLI
ALPHA [a-zA-Z_]
DIGIT [0-9]
XIGIT [0-9a-fA-F]
ALNUM [a-zA-Z_0-9]
WHITE [ \t]
include ^{WHITE}*include{WHITE}*\".*\"{WHITE}*;
%%
{include} {
char *start, *end;
if (!ifs->depth)
cf_error("Include not allowed in CLI");
start = strchr(yytext, '"');
start++;
end = strchr(start, '"');
*end = 0;
if (start == end)
cf_error("Include with empty argument");
cf_include(start, end-start);
}
{DIGIT}+\.{DIGIT}+\.{DIGIT}+\.{DIGIT}+ {
if (!ip4_pton(yytext, &cf_lval.ip4))
cf_error("Invalid IPv4 address %s", yytext);
return IP4;
}
({XIGIT}*::|({XIGIT}*:){3,})({XIGIT}*|{DIGIT}+\.{DIGIT}+\.{DIGIT}+\.{DIGIT}+) {
if (!ip6_pton(yytext, &cf_lval.ip6))
cf_error("Invalid IPv6 address %s", yytext);
return IP6;
}
0x{XIGIT}+ {
char *e;
unsigned long int l;
errno = 0;
l = strtoul(yytext+2, &e, 16);
if (e && *e || errno == ERANGE || (unsigned long int)(unsigned int) l != l)
cf_error("Number out of range");
cf_lval.i = l;
return NUM;
}
{DIGIT}+ {
char *e;
unsigned long int l;
errno = 0;
l = strtoul(yytext, &e, 10);
if (e && *e || errno == ERANGE || (unsigned long int)(unsigned int) l != l)
cf_error("Number out of range");
cf_lval.i = l;
return NUM;
}
else: {
/* Hack to distinguish if..else from else: in case */
return ELSECOL;
}
({ALPHA}{ALNUM}*|[']({ALNUM}|[-]|[\.]|[:])*[']) {
if(*yytext == '\'') {
yytext[yyleng-1] = 0;
yytext++;
}
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_get_sym(yytext, h);
return SYM;
}
<CLI>(.|\n) {
BEGIN(INITIAL);
return CLI_MARKER;
}
\.\. {
return DDOT;
}
[={}:;,.()+*/%<>~\[\]?!\|-] {
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>> { if (check_eof()) return END; }
{WHITE}+
\n ifs->lino++;
# BEGIN(COMMENT);
\/\* BEGIN(CCOMM);
. cf_error("Unknown character");
<COMMENT>\n {
ifs->lino++;
BEGIN(INITIAL);
}
<COMMENT>.
<CCOMM>\*\/ BEGIN(INITIAL);
<CCOMM>\n ifs->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;
\[\= return PO;
\=\] return PC;
%%
static int
cf_hash(byte *c)
{
unsigned int h = 13;
while (*c)
h = (h * 37) + *c++;
return h;
}
/*
* IFS stack - it contains structures needed for recursive processing
* of include in config files. On the top of the stack is a structure
* for currently processed file. Other structures are either for
* active files interrupted because of include directive (these have
* fd and flex buffer) or for inactive files scheduled to be processed
* later (when parent requested including of several files by wildcard
* match - these do not have fd and flex buffer yet).
*
* FIXME: Most of these ifs and include functions are really sysdep/unix.
*/
static struct include_file_stack *
push_ifs(struct include_file_stack *old)
{
struct include_file_stack *ret;
ret = cfg_allocz(sizeof(struct include_file_stack));
ret->lino = 1;
ret->prev = old;
return ret;
}
static struct include_file_stack *
pop_ifs(struct include_file_stack *old)
{
yy_delete_buffer(old->buffer);
close(old->fd);
return old->prev;
}
static void
enter_ifs(struct include_file_stack *new)
{
if (!new->buffer)
{
new->fd = open(new->file_name, O_RDONLY);
if (new->fd < 0)
{
ifs = ifs->up;
cf_error("Unable to open included file %s: %m", new->file_name);
}
new->buffer = yy_create_buffer(NULL, YY_BUF_SIZE);
}
yy_switch_to_buffer(new->buffer);
}
/**
* cf_lex_unwind - unwind lexer state during error
*
* cf_lex_unwind() frees the internal state on IFS stack when the lexical
* analyzer is terminated by cf_error().
*/
void
cf_lex_unwind(void)
{
struct include_file_stack *n;
for (n = ifs; n != ifs_head; n = n->prev)
{
/* Memory is freed automatically */
if (n->buffer)
yy_delete_buffer(n->buffer);
if (n->fd)
close(n->fd);
}
ifs = ifs_head;
}
static void
cf_include(char *arg, int alen)
{
struct include_file_stack *base_ifs = ifs;
int new_depth, rv, i;
char *patt;
glob_t g = {};
new_depth = ifs->depth + 1;
if (new_depth > MAX_INCLUDE_DEPTH)
cf_error("Max include depth reached");
/* expand arg to properly handle relative filenames */
if (*arg != '/')
{
int dlen = strlen(ifs->file_name);
char *dir = alloca(dlen + 1);
patt = alloca(dlen + alen + 2);
memcpy(dir, ifs->file_name, dlen + 1);
sprintf(patt, "%s/%s", dirname(dir), arg);
}
else
patt = arg;
/* Skip globbing if there are no wildcards, mainly to get proper
response when the included config file is missing */
if (!strpbrk(arg, "?*["))
{
ifs = push_ifs(ifs);
ifs->file_name = cfg_strdup(patt);
ifs->depth = new_depth;
ifs->up = base_ifs;
enter_ifs(ifs);
return;
}
/* Expand the pattern */
rv = glob(patt, GLOB_ERR | GLOB_NOESCAPE, NULL, &g);
if (rv == GLOB_ABORTED)
cf_error("Unable to match pattern %s: %m", patt);
if ((rv != 0) || (g.gl_pathc <= 0))
return;
/*
* Now we put all found files to ifs stack in reverse order, they
* will be activated and processed in order as ifs stack is popped
* by pop_ifs() and enter_ifs() in check_eof().
*/
for(i = g.gl_pathc - 1; i >= 0; i--)
{
char *fname = g.gl_pathv[i];
struct stat fs;
if (stat(fname, &fs) < 0)
{
globfree(&g);
cf_error("Unable to stat included file %s: %m", fname);
}
if (fs.st_mode & S_IFDIR)
continue;
/* Prepare new stack item */
ifs = push_ifs(ifs);
ifs->file_name = cfg_strdup(fname);
ifs->depth = new_depth;
ifs->up = base_ifs;
}
globfree(&g);
enter_ifs(ifs);
}
static int
check_eof(void)
{
if (ifs == ifs_head)
{
/* EOF in main config file */
ifs->lino = 1; /* Why this? */
return 1;
}
ifs = pop_ifs(ifs);
enter_ifs(ifs);
return 0;
}
static struct symbol *
cf_new_sym(byte *c, uint h0)
{
uint h = h0 & (SYM_HASH_SIZE-1);
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(struct config *cfg, byte *c, uint h0)
{
uint h = h0 & (SYM_HASH_SIZE-1);
struct symbol *s, **ht;
if (ht = cfg->sym_hash)
{
for(s = ht[h]; s; s=s->next)
if (!strcmp(s->name, c) && s->scope->active)
return s;
}
if (ht = cfg->sym_fallback)
{
/* We know only top-level scope is active */
for(s = ht[h]; s; s=s->next)
if (!strcmp(s->name, c) && s->scope->active)
return s;
}
return NULL;
}
static inline struct symbol *
cf_get_sym(byte *c, uint h0)
{
return cf_find_sym(new_config, c, h0) ?: cf_new_sym(c, h0);
}
/**
* cf_find_symbol - find a symbol by name
* @cfg: specificed config
* @c: symbol name
*
* This functions searches the symbol table in the config @cfg 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(struct config *cfg, byte *c)
{
return cf_find_sym(cfg, c, cf_hash(c));
}
/**
* cf_get_symbol - get a symbol by name
* @c: symbol name
*
* This functions searches the symbol table of the currently parsed config
* (@new_config) for a symbol of given name. It returns either the already
* existing symbol or a newly allocated undefined (%SYM_VOID) symbol if no
* existing symbol is found.
*/
struct symbol *
cf_get_symbol(byte *c)
{
return cf_get_sym(c, cf_hash(c));
}
struct symbol *
cf_default_name(char *template, int *counter)
{
char buf[SYM_MAX_LEN];
struct symbol *s;
char *perc = strchr(template, '%');
for(;;)
{
bsprintf(buf, template, ++(*counter));
s = cf_get_sym(buf, cf_hash(buf));
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->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
* @c: configuration structure
*
* cf_lex_init() initializes the lexical analyzer and prepares it for
* parsing of a new input.
*/
void
cf_lex_init(int is_cli, struct config *c)
{
if (!kw_hash_inited)
cf_lex_init_kh();
ifs_head = ifs = push_ifs(NULL);
if (!is_cli)
{
ifs->file_name = c->file_name;
ifs->fd = c->file_fd;
ifs->depth = 1;
}
yyrestart(NULL);
ifs->buffer = YY_CURRENT_BUFFER;
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)
{
if (cf_symbol_is_constant(sym))
return "constant";
switch (sym->class)
{
case SYM_VOID:
return "undefined";
case SYM_PROTO:
return "protocol";
case SYM_TEMPLATE:
return "protocol template";
case SYM_FUNCTION:
return "function";
case SYM_FILTER:
return "filter";
case SYM_TABLE:
return "routing table";
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.
*/