diff options
Diffstat (limited to 'src/cfgcond.c')
-rw-r--r-- | src/cfgcond.c | 521 |
1 files changed, 521 insertions, 0 deletions
diff --git a/src/cfgcond.c b/src/cfgcond.c new file mode 100644 index 0000000..5fb7069 --- /dev/null +++ b/src/cfgcond.c @@ -0,0 +1,521 @@ +/* + * Configuration condition preprocessor + * + * Copyright 2000-2021 Willy Tarreau <w@1wt.eu> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + */ + +#include <haproxy/api.h> +#include <haproxy/arg.h> +#include <haproxy/cfgcond.h> +#include <haproxy/global.h> +#include <haproxy/tools.h> + +/* supported condition predicates */ +const struct cond_pred_kw cond_predicates[] = { + { "defined", CFG_PRED_DEFINED, ARG1(1, STR) }, + { "feature", CFG_PRED_FEATURE, ARG1(1, STR) }, + { "streq", CFG_PRED_STREQ, ARG2(2, STR, STR) }, + { "strneq", CFG_PRED_STRNEQ, ARG2(2, STR, STR) }, + { "version_atleast", CFG_PRED_VERSION_ATLEAST, ARG1(1, STR) }, + { "version_before", CFG_PRED_VERSION_BEFORE, ARG1(1, STR) }, + { "openssl_version_atleast", CFG_PRED_OSSL_VERSION_ATLEAST, ARG1(1, STR) }, + { "openssl_version_before", CFG_PRED_OSSL_VERSION_BEFORE, ARG1(1, STR) }, + { "ssllib_name_startswith", CFG_PRED_SSLLIB_NAME_STARTSWITH, ARG1(1, STR) }, + { NULL, CFG_PRED_NONE, 0 } +}; + +/* looks up a cond predicate matching the keyword in <str>, possibly followed + * by a parenthesis. Returns a pointer to it or NULL if not found. + */ +const struct cond_pred_kw *cfg_lookup_cond_pred(const char *str) +{ + const struct cond_pred_kw *ret; + int len = strcspn(str, " ("); + + for (ret = &cond_predicates[0]; ret->word; ret++) { + if (len != strlen(ret->word)) + continue; + if (strncmp(str, ret->word, len) != 0) + continue; + return ret; + } + return NULL; +} + +/* Frees <term> and its args. NULL is supported and does nothing. */ +void cfg_free_cond_term(struct cfg_cond_term *term) +{ + if (!term) + return; + + if (term->type == CCTT_PAREN) { + cfg_free_cond_expr(term->expr); + term->expr = NULL; + } + + free_args(term->args); + free(term->args); + free(term); +} + +/* Parse an indirect input text as a possible config condition term. + * Returns <0 on parsing error, 0 if the parser is desynchronized, or >0 on + * success. <term> is allocated and filled with the parsed info, and <text> + * is updated on success to point to the first unparsed character, or is left + * untouched on failure. On success, the caller must free <term> using + * cfg_free_cond_term(). An error will be set in <err> on error, and only + * in this case. In this case the first bad character will be reported in + * <errptr>. <maxdepth> corresponds to the maximum recursion depth permitted, + * it is decremented on each recursive call and the parsing will fail one + * reaching <= 0. + */ +int cfg_parse_cond_term(const char **text, struct cfg_cond_term **term, char **err, const char **errptr, int maxdepth) +{ + struct cfg_cond_term *t; + const char *in = *text; + const char *end_ptr; + int err_arg; + int nbargs; + char *end; + long val; + + while (*in == ' ' || *in == '\t') + in++; + + if (!*in) /* empty term does not parse */ + return 0; + + *term = NULL; + if (maxdepth <= 0) + goto fail0; + + t = *term = calloc(1, sizeof(**term)); + if (!t) { + memprintf(err, "memory allocation error while parsing conditional expression '%s'", *text); + goto fail1; + } + + t->type = CCTT_NONE; + t->args = NULL; + t->neg = 0; + + /* !<term> negates the term. White spaces permitted */ + while (*in == '!') { + t->neg = !t->neg; + do { in++; } while (*in == ' ' || *in == '\t'); + } + + val = strtol(in, &end, 0); + if (end != in) { + t->type = val ? CCTT_TRUE : CCTT_FALSE; + *text = end; + return 1; + } + + /* Try to parse '(' EXPR ')' */ + if (*in == '(') { + int ret; + + t->type = CCTT_PAREN; + t->args = NULL; + + do { in++; } while (*in == ' ' || *in == '\t'); + ret = cfg_parse_cond_expr(&in, &t->expr, err, errptr, maxdepth - 1); + if (ret == -1) + goto fail2; + if (ret == 0) + goto fail0; + + /* find the closing ')' */ + while (*in == ' ' || *in == '\t') + in++; + if (*in != ')') { + memprintf(err, "expected ')' after conditional expression '%s'", *text); + goto fail1; + } + do { in++; } while (*in == ' ' || *in == '\t'); + *text = in; + return 1; + } + + /* below we'll likely all make_arg_list() so we must return only via + * the <done> label which frees the arg list. + */ + t->pred = cfg_lookup_cond_pred(in); + if (t->pred) { + t->type = CCTT_PRED; + nbargs = make_arg_list(in + strlen(t->pred->word), -1, + t->pred->arg_mask, &t->args, err, + &end_ptr, &err_arg, NULL); + if (nbargs < 0) { + memprintf(err, "%s in argument %d of predicate '%s' used in conditional expression", *err, err_arg, t->pred->word); + if (errptr) + *errptr = end_ptr; + goto fail2; + } + *text = end_ptr; + return 1; + } + + fail0: + memprintf(err, "unparsable conditional expression '%s'", *text); + fail1: + if (errptr) + *errptr = *text; + fail2: + cfg_free_cond_term(*term); + *term = NULL; + return -1; +} + +/* evaluate a condition term on a .if/.elif line. The condition was already + * parsed in <term>. Returns -1 on error (in which case err is filled with a + * message, and only in this case), 0 if the condition is false, 1 if it's + * true. + */ +int cfg_eval_cond_term(const struct cfg_cond_term *term, char **err) +{ + int ret = -1; + + if (term->type == CCTT_FALSE) + ret = 0; + else if (term->type == CCTT_TRUE) + ret = 1; + else if (term->type == CCTT_PRED) { + /* here we know we have a valid predicate with valid arguments + * placed in term->args (which the caller will free). + */ + switch (term->pred->prd) { + case CFG_PRED_DEFINED: // checks if arg exists as an environment variable + ret = getenv(term->args[0].data.str.area) != NULL; + break; + + case CFG_PRED_FEATURE: { // checks if the arg matches an enabled feature + const char *p; + + ret = 0; // assume feature not found + for (p = build_features; (p = strstr(p, term->args[0].data.str.area)); p++) { + if (p > build_features && + (p[term->args[0].data.str.data] == ' ' || + p[term->args[0].data.str.data] == 0)) { + if (*(p-1) == '+') { // e.g. "+OPENSSL" + ret = 1; + break; + } + else if (*(p-1) == '-') { // e.g. "-OPENSSL" + ret = 0; + break; + } + /* it was a sub-word, let's restart from next place */ + } + } + break; + } + case CFG_PRED_STREQ: // checks if the two arg are equal + ret = strcmp(term->args[0].data.str.area, term->args[1].data.str.area) == 0; + break; + + case CFG_PRED_STRNEQ: // checks if the two arg are different + ret = strcmp(term->args[0].data.str.area, term->args[1].data.str.area) != 0; + break; + + case CFG_PRED_VERSION_ATLEAST: // checks if the current version is at least this one + ret = compare_current_version(term->args[0].data.str.area) <= 0; + break; + + case CFG_PRED_VERSION_BEFORE: // checks if the current version is older than this one + ret = compare_current_version(term->args[0].data.str.area) > 0; + break; + + case CFG_PRED_OSSL_VERSION_ATLEAST: { // checks if the current openssl version is at least this one + int opensslret = openssl_compare_current_version(term->args[0].data.str.area); + + if (opensslret < -1) /* can't parse the string or no openssl available */ + ret = -1; + else + ret = opensslret <= 0; + break; + } + case CFG_PRED_OSSL_VERSION_BEFORE: { // checks if the current openssl version is older than this one + int opensslret = openssl_compare_current_version(term->args[0].data.str.area); + + if (opensslret < -1) /* can't parse the string or no openssl available */ + ret = -1; + else + ret = opensslret > 0; + break; + } + case CFG_PRED_SSLLIB_NAME_STARTSWITH: { // checks if the current SSL library's name starts with a specified string (can be used to distinguish OpenSSL from LibreSSL or BoringSSL) + ret = openssl_compare_current_name(term->args[0].data.str.area) == 0; + break; + } + default: + memprintf(err, "internal error: unhandled conditional expression predicate '%s'", term->pred->word); + break; + } + } + else if (term->type == CCTT_PAREN) { + ret = cfg_eval_cond_expr(term->expr, err); + } + else { + memprintf(err, "internal error: unhandled condition term type %d", (int)term->type); + } + + if (ret >= 0 && term->neg) + ret = !ret; + return ret; +} + + +/* Frees <expr> and its terms and args. NULL is supported and does nothing. */ +void cfg_free_cond_and(struct cfg_cond_and *expr) +{ + struct cfg_cond_and *prev; + + while (expr) { + cfg_free_cond_term(expr->left); + prev = expr; + expr = expr->right; + free(prev); + } +} + +/* Frees <expr> and its terms and args. NULL is supported and does nothing. */ +void cfg_free_cond_expr(struct cfg_cond_expr *expr) +{ + struct cfg_cond_expr *prev; + + while (expr) { + cfg_free_cond_and(expr->left); + prev = expr; + expr = expr->right; + free(prev); + } +} + +/* Parse an indirect input text as a possible config condition sub-expr. + * Returns <0 on parsing error, 0 if the parser is desynchronized, or >0 on + * success. <expr> is filled with the parsed info, and <text> is updated on + * success to point to the first unparsed character, or is left untouched + * on failure. On success, the caller will have to free all lower-level + * allocated structs using cfg_free_cond_expr(). An error will be set in + * <err> on error, and only in this case. In this case the first bad + * character will be reported in <errptr>. <maxdepth> corresponds to the + * maximum recursion depth permitted, it is decremented on each recursive + * call and the parsing will fail one reaching <= 0. + */ +int cfg_parse_cond_and(const char **text, struct cfg_cond_and **expr, char **err, const char **errptr, int maxdepth) +{ + struct cfg_cond_and *e; + const char *in = *text; + int ret = -1; + + if (!*in) /* empty expr does not parse */ + return 0; + + *expr = NULL; + if (maxdepth <= 0) { + memprintf(err, "unparsable conditional sub-expression '%s'", in); + if (errptr) + *errptr = in; + goto done; + } + + e = *expr = calloc(1, sizeof(**expr)); + if (!e) { + memprintf(err, "memory allocation error while parsing conditional expression '%s'", *text); + goto done; + } + + ret = cfg_parse_cond_term(&in, &e->left, err, errptr, maxdepth - 1); + if (ret == -1) // parse error, error already reported + goto done; + + if (ret == 0) { + /* ret == 0, no other way to parse this */ + memprintf(err, "unparsable conditional sub-expression '%s'", in); + if (errptr) + *errptr = in; + ret = -1; + goto done; + } + + /* ret=1, we have a term in the left hand set */ + + /* find an optional '&&' */ + while (*in == ' ' || *in == '\t') + in++; + + *text = in; + if (in[0] != '&' || in[1] != '&') + goto done; + + /* we have a '&&', let's parse the right handset's subexp */ + in += 2; + while (*in == ' ' || *in == '\t') + in++; + + ret = cfg_parse_cond_and(&in, &e->right, err, errptr, maxdepth - 1); + if (ret > 0) + *text = in; + done: + if (ret < 0) { + cfg_free_cond_and(*expr); + *expr = NULL; + } + return ret; +} + +/* Parse an indirect input text as a possible config condition term. + * Returns <0 on parsing error, 0 if the parser is desynchronized, or >0 on + * success. <expr> is filled with the parsed info, and <text> is updated on + * success to point to the first unparsed character, or is left untouched + * on failure. On success, the caller will have to free all lower-level + * allocated structs using cfg_free_cond_expr(). An error will be set in + * <err> on error, and only in this case. In this case the first bad + * character will be reported in <errptr>. <maxdepth> corresponds to the + * maximum recursion depth permitted, it is decremented on each recursive call + * and the parsing will fail one reaching <= 0. + */ +int cfg_parse_cond_expr(const char **text, struct cfg_cond_expr **expr, char **err, const char **errptr, int maxdepth) +{ + struct cfg_cond_expr *e; + const char *in = *text; + int ret = -1; + + if (!*in) /* empty expr does not parse */ + return 0; + + *expr = NULL; + if (maxdepth <= 0) { + memprintf(err, "unparsable conditional expression '%s'", in); + if (errptr) + *errptr = in; + goto done; + } + + e = *expr = calloc(1, sizeof(**expr)); + if (!e) { + memprintf(err, "memory allocation error while parsing conditional expression '%s'", *text); + goto done; + } + + ret = cfg_parse_cond_and(&in, &e->left, err, errptr, maxdepth - 1); + if (ret == -1) // parse error, error already reported + goto done; + + if (ret == 0) { + /* ret == 0, no other way to parse this */ + memprintf(err, "unparsable conditional expression '%s'", in); + if (errptr) + *errptr = in; + ret = -1; + goto done; + } + + /* ret=1, we have a sub-expr in the left hand set */ + + /* find an optional '||' */ + while (*in == ' ' || *in == '\t') + in++; + + *text = in; + if (in[0] != '|' || in[1] != '|') + goto done; + + /* we have a '||', let's parse the right handset's subexp */ + in += 2; + while (*in == ' ' || *in == '\t') + in++; + + ret = cfg_parse_cond_expr(&in, &e->right, err, errptr, maxdepth - 1); + if (ret > 0) + *text = in; + done: + if (ret < 0) { + cfg_free_cond_expr(*expr); + *expr = NULL; + } + return ret; +} + +/* evaluate an sub-expression on a .if/.elif line. The expression is valid and + * was already parsed in <expr>. Returns -1 on error (in which case err is + * filled with a message, and only in this case), 0 if the condition is false, + * 1 if it's true. + */ +int cfg_eval_cond_and(struct cfg_cond_and *expr, char **err) +{ + int ret; + + /* AND: loop on terms and sub-exp's terms as long as they're TRUE + * (stop on FALSE and ERROR). + */ + while ((ret = cfg_eval_cond_term(expr->left, err)) > 0 && expr->right) + expr = expr->right; + return ret; +} + +/* evaluate an expression on a .if/.elif line. The expression is valid and was + * already parsed in <expr>. Returns -1 on error (in which case err is filled + * with a message, and only in this case), 0 if the condition is false, 1 if + * it's true. + */ +int cfg_eval_cond_expr(struct cfg_cond_expr *expr, char **err) +{ + int ret; + + /* OR: loop on sub-exps as long as they're FALSE (stop on TRUE and ERROR) */ + while ((ret = cfg_eval_cond_and(expr->left, err)) == 0 && expr->right) + expr = expr->right; + return ret; +} + +/* evaluate a condition on a .if/.elif line. The condition is already tokenized + * in <err>. Returns -1 on error (in which case err is filled with a message, + * and only in this case), 0 if the condition is false, 1 if it's true. If + * <errptr> is not NULL, it's set to the first invalid character on error. + */ +int cfg_eval_condition(char **args, char **err, const char **errptr) +{ + struct cfg_cond_expr *expr = NULL; + const char *text = args[0]; + int ret = -1; + + if (!*text) /* note: empty = false */ + return 0; + + ret = cfg_parse_cond_expr(&text, &expr, err, errptr, MAX_CFG_RECURSION); + if (ret != 0) { + if (ret == -1) // parse error, error already reported + goto done; + while (*text == ' ' || *text == '\t') + text++; + + if (*text) { + ret = -1; + memprintf(err, "unexpected character '%c' at the end of conditional expression '%s'", + *text, args[0]); + goto fail; + } + + ret = cfg_eval_cond_expr(expr, err); + goto done; + } + + /* ret == 0, no other way to parse this */ + ret = -1; + memprintf(err, "unparsable conditional expression '%s'", args[0]); + fail: + if (errptr) + *errptr = text; + done: + cfg_free_cond_expr(expr); + return ret; +} |