/* * 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 struct symbol *cf_find_sym(byte *c, unsigned int 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}+ { ip4_addr a; if (!ip4_pton(yytext, &a)) cf_error("Invalid IPv4 address %s", yytext); #ifdef IPV6 cf_lval.i32 = ip4_to_u32(a); return RTRID; #else cf_lval.a = ipa_from_ip4(a); return IPA; #endif } ({XIGIT}*::|({XIGIT}*:){3,})({XIGIT}*|{DIGIT}+\.{DIGIT}+\.{DIGIT}+\.{DIGIT}+) { #ifdef IPV6 if (ipa_pton(yytext, &cf_lval.a)) return IPA; cf_error("Invalid IPv6 address %s", yytext); #else cf_error("This is an IPv4 router, therefore IPv6 addresses are not supported"); #endif } 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_find_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, 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, 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"; case SYM_ROA: return "ROA 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. */