From 80f3c19bc1b989ab7ba2b917193e8bd3f998ba39 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 8 Mar 2021 18:18:33 +0100 Subject: [PATCH] scanner: introduce start condition stack Add a small initial chunk of flex start conditionals. This starts with two low-hanging fruits, numgen and j/symhash. NUMGEN and HASH start conditions are entered from flex when the corresponding expression token is encountered. Flex returns to the INIT condition when the bison parser has seen a complete numgen/hash statement. This intentionally uses a stack rather than BEGIN() to eventually support nested states. The scanner_pop_start_cond() function argument is not used yet, but will need to be used later to deal with nesting. Signed-off-by: Florian Westphal (cherry picked from commit 5896772fe3c5f01696188ea04957a825ee601b12) --- include/parser.h | 8 ++++++++ src/parser_bison.y | 11 +++++++---- src/scanner.l | 36 +++++++++++++++++++++++++++++------- 3 files changed, 44 insertions(+), 11 deletions(-) diff --git a/include/parser.h b/include/parser.h index 9baa3a4db789f..b2ebd7aa226c5 100644 --- a/include/parser.h +++ b/include/parser.h @@ -26,6 +26,12 @@ struct parser_state { struct list_head *cmds; }; +enum startcond_type { + PARSER_SC_BEGIN, + PARSER_SC_EXPR_HASH, + PARSER_SC_EXPR_NUMGEN, +}; + struct mnl_socket; extern void parser_init(struct nft_ctx *nft, struct parser_state *state, @@ -45,4 +51,6 @@ extern void scanner_push_buffer(void *scanner, const struct input_descriptor *indesc, const char *buffer); +extern void scanner_pop_start_cond(void *scanner, enum startcond_type sc); + #endif /* NFTABLES_PARSER_H */ diff --git a/src/parser_bison.y b/src/parser_bison.y index 8644f66106496..da3fafcd1eeb1 100644 --- a/src/parser_bison.y +++ b/src/parser_bison.y @@ -857,6 +857,9 @@ opt_newline : NEWLINE | /* empty */ ; +close_scope_hash : { scanner_pop_start_cond(nft->scanner, PARSER_SC_EXPR_HASH); }; +close_scope_numgen : { scanner_pop_start_cond(nft->scanner, PARSER_SC_EXPR_NUMGEN); }; + common_block : INCLUDE QUOTED_STRING stmt_separator { if (scanner_include_file(nft, scanner, $2, &@$) < 0) { @@ -4811,7 +4814,7 @@ numgen_type : INC { $$ = NFT_NG_INCREMENTAL; } | RANDOM { $$ = NFT_NG_RANDOM; } ; -numgen_expr : NUMGEN numgen_type MOD NUM offset_opt +numgen_expr : NUMGEN numgen_type MOD NUM offset_opt close_scope_numgen { $$ = numgen_expr_alloc(&@$, $2, $4, $5); } @@ -4868,17 +4871,17 @@ xfrm_expr : IPSEC xfrm_dir xfrm_spnum xfrm_state_key } ; -hash_expr : JHASH expr MOD NUM SEED NUM offset_opt +hash_expr : JHASH expr MOD NUM SEED NUM offset_opt close_scope_hash { $$ = hash_expr_alloc(&@$, $4, true, $6, $7, NFT_HASH_JENKINS); $$->hash.expr = $2; } - | JHASH expr MOD NUM offset_opt + | JHASH expr MOD NUM offset_opt close_scope_hash { $$ = hash_expr_alloc(&@$, $4, false, 0, $5, NFT_HASH_JENKINS); $$->hash.expr = $2; } - | SYMHASH MOD NUM offset_opt + | SYMHASH MOD NUM offset_opt close_scope_hash { $$ = hash_expr_alloc(&@$, $3, false, 0, $4, NFT_HASH_SYM); } diff --git a/src/scanner.l b/src/scanner.l index 8bde1fbe912d8..ec8f252fbc8c8 100644 --- a/src/scanner.l +++ b/src/scanner.l @@ -98,6 +98,8 @@ static void reset_pos(struct parser_state *state, struct location *loc) state->indesc->column = 1; } +static void scanner_push_start_cond(void *scanner, enum startcond_type type); + #define YY_USER_ACTION { \ update_pos(yyget_extra(yyscanner), yylloc, yyleng); \ update_offset(yyget_extra(yyscanner), yylloc, yyleng); \ @@ -193,6 +195,9 @@ addrstring ({macaddr}|{ip4addr}|{ip6addr}) %option yylineno %option nodefault %option warn +%option stack +%s SCANSTATE_EXPR_HASH +%s SCANSTATE_EXPR_NUMGEN %% @@ -551,15 +556,21 @@ addrstring ({macaddr}|{ip4addr}|{ip6addr}) "state" { return STATE; } "status" { return STATUS; } -"numgen" { return NUMGEN; } -"inc" { return INC; } -"mod" { return MOD; } -"offset" { return OFFSET; } +"numgen" { scanner_push_start_cond(yyscanner, SCANSTATE_EXPR_NUMGEN); return NUMGEN; } +{ + "inc" { return INC; } +} -"jhash" { return JHASH; } -"symhash" { return SYMHASH; } -"seed" { return SEED; } +"jhash" { scanner_push_start_cond(yyscanner, SCANSTATE_EXPR_HASH); return JHASH; } +"symhash" { scanner_push_start_cond(yyscanner, SCANSTATE_EXPR_HASH); return SYMHASH; } +{ + "seed" { return SEED; } +} +{ + "mod" { return MOD; } + "offset" { return OFFSET; } +} "dup" { return DUP; } "fwd" { return FWD; } @@ -973,3 +984,14 @@ void scanner_destroy(struct nft_ctx *nft) input_descriptor_list_destroy(state); yylex_destroy(nft->scanner); } + +static void scanner_push_start_cond(void *scanner, enum startcond_type type) +{ + yy_push_state((int)type, scanner); +} + +void scanner_pop_start_cond(void *scanner, enum startcond_type t) +{ + yy_pop_state(scanner); + (void)yy_top_state(scanner); /* suppress gcc warning wrt. unused function */ +} -- 2.33.0