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haproxy/src/http_rules.c
Willy Tarreau bc1223be79 MINOR: http-rules: add a new "ignore-empty" option to redirects. 
Sometimes it is convenient to remap large sets of URIs to new ones (e.g.
after a site migration for example). This can be achieved using
"http-request redirect" combined with maps, but one difficulty there is
that non-matching entries will return an empty response. In order to
avoid this, duplicating the operation as an ACL condition ending in
"-m found" is possible but it becomes complex and error-prone while it's
known that an empty URL is not valid in a location header.

This patch addresses this by improving the redirect rules to be able to
simply ignore the rule and skip to the next one if the result of the
evaluation of the "location" expression is empty. However in order not
to break existing setups, it requires a new "ignore-empty" keyword.

There used to be an ACT_FLAG_FINAL on redirect rules that's used during
the parsing to emit a warning if followed by another rule, so here we
only set it if the option is not there. The http_apply_redirect_rule()
function now returns a 3rd value to mention that it did nothing and
that this was not an error, so that callers can just ignore the rule.
The regular "redirect" rules were not modified however since this does
not apply there.

The map_redirect VTC was completed with such a test and updated to 2.5
and an example was added into the documentation.
2021-09-02 17:06:18 +02:00

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/*
* HTTP rules parsing and registration
*
* Copyright 2000-2018 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 <sys/types.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
#include <haproxy/acl.h>
#include <haproxy/action.h>
#include <haproxy/api.h>
#include <haproxy/arg.h>
#include <haproxy/capture-t.h>
#include <haproxy/cfgparse.h>
#include <haproxy/chunk.h>
#include <haproxy/global.h>
#include <haproxy/http.h>
#include <haproxy/http_rules.h>
#include <haproxy/log.h>
#include <haproxy/pool.h>
#include <haproxy/proxy.h>
#include <haproxy/sample.h>
#include <haproxy/tools.h>
#include <haproxy/version.h>
/* List head of all known action keywords for "http-request" */
struct action_kw_list http_req_keywords = {
.list = LIST_HEAD_INIT(http_req_keywords.list)
};
/* List head of all known action keywords for "http-response" */
struct action_kw_list http_res_keywords = {
.list = LIST_HEAD_INIT(http_res_keywords.list)
};
/* List head of all known action keywords for "http-after-response" */
struct action_kw_list http_after_res_keywords = {
.list = LIST_HEAD_INIT(http_after_res_keywords.list)
};
/*
* Return the struct http_req_action_kw associated to a keyword.
*/
struct action_kw *action_http_req_custom(const char *kw)
{
return action_lookup(&http_req_keywords.list, kw);
}
/*
* Return the struct http_res_action_kw associated to a keyword.
*/
struct action_kw *action_http_res_custom(const char *kw)
{
return action_lookup(&http_res_keywords.list, kw);
}
/*
* Return the struct http_after_res_action_kw associated to a keyword.
*/
struct action_kw *action_http_after_res_custom(const char *kw)
{
return action_lookup(&http_after_res_keywords.list, kw);
}
/* parse an "http-request" rule */
struct act_rule *parse_http_req_cond(const char **args, const char *file, int linenum, struct proxy *proxy)
{
struct act_rule *rule;
const struct action_kw *custom = NULL;
int cur_arg;
rule = calloc(1, sizeof(*rule));
if (!rule) {
ha_alert("parsing [%s:%d]: out of memory.\n", file, linenum);
goto out_err;
}
rule->from = ACT_F_HTTP_REQ;
if (((custom = action_http_req_custom(args[0])) != NULL)) {
char *errmsg = NULL;
cur_arg = 1;
/* try in the module list */
rule->kw = custom;
if (custom->flags & KWF_EXPERIMENTAL) {
if (!experimental_directives_allowed) {
ha_alert("parsing [%s:%d] : '%s' action is experimental, must be allowed via a global 'expose-experimental-directives'\n",
file, linenum, custom->kw);
goto out_err;
}
mark_tainted(TAINTED_CONFIG_EXP_KW_DECLARED);
}
if (custom->parse(args, &cur_arg, proxy, rule, &errmsg) == ACT_RET_PRS_ERR) {
ha_alert("parsing [%s:%d] : error detected in %s '%s' while parsing 'http-request %s' rule : %s.\n",
file, linenum, proxy_type_str(proxy), proxy->id, args[0], errmsg);
free(errmsg);
goto out_err;
}
else if (errmsg) {
ha_warning("parsing [%s:%d] : %s.\n", file, linenum, errmsg);
free(errmsg);
}
}
else {
const char *best = action_suggest(args[0], &http_req_keywords.list, NULL);
action_build_list(&http_req_keywords.list, &trash);
ha_alert("parsing [%s:%d]: 'http-request' expects %s, but got '%s'%s.%s%s%s\n",
file, linenum, trash.area,
args[0], *args[0] ? "" : " (missing argument)",
best ? " Did you mean '" : "",
best ? best : "",
best ? "' maybe ?" : "");
goto out_err;
}
if (strcmp(args[cur_arg], "if") == 0 || strcmp(args[cur_arg], "unless") == 0) {
struct acl_cond *cond;
char *errmsg = NULL;
if ((cond = build_acl_cond(file, linenum, &proxy->acl, proxy, args+cur_arg, &errmsg)) == NULL) {
ha_alert("parsing [%s:%d] : error detected while parsing an 'http-request %s' condition : %s.\n",
file, linenum, args[0], errmsg);
free(errmsg);
goto out_err;
}
rule->cond = cond;
}
else if (*args[cur_arg]) {
ha_alert("parsing [%s:%d]: 'http-request %s' expects"
" either 'if' or 'unless' followed by a condition but found '%s'.\n",
file, linenum, args[0], args[cur_arg]);
goto out_err;
}
return rule;
out_err:
free(rule);
return NULL;
}
/* parse an "http-respose" rule */
struct act_rule *parse_http_res_cond(const char **args, const char *file, int linenum, struct proxy *proxy)
{
struct act_rule *rule;
const struct action_kw *custom = NULL;
int cur_arg;
rule = calloc(1, sizeof(*rule));
if (!rule) {
ha_alert("parsing [%s:%d]: out of memory.\n", file, linenum);
goto out_err;
}
rule->from = ACT_F_HTTP_RES;
if (((custom = action_http_res_custom(args[0])) != NULL)) {
char *errmsg = NULL;
cur_arg = 1;
/* try in the module list */
rule->kw = custom;
if (custom->flags & KWF_EXPERIMENTAL) {
if (!experimental_directives_allowed) {
ha_alert("parsing [%s:%d] : '%s' action is experimental, must be allowed via a global 'expose-experimental-directives'\n",
file, linenum, custom->kw);
goto out_err;
}
mark_tainted(TAINTED_CONFIG_EXP_KW_DECLARED);
}
if (custom->parse(args, &cur_arg, proxy, rule, &errmsg) == ACT_RET_PRS_ERR) {
ha_alert("parsing [%s:%d] : error detected in %s '%s' while parsing 'http-response %s' rule : %s.\n",
file, linenum, proxy_type_str(proxy), proxy->id, args[0], errmsg);
free(errmsg);
goto out_err;
}
else if (errmsg) {
ha_warning("parsing [%s:%d] : %s.\n", file, linenum, errmsg);
free(errmsg);
}
}
else {
const char *best = action_suggest(args[0], &http_res_keywords.list, NULL);
action_build_list(&http_res_keywords.list, &trash);
ha_alert("parsing [%s:%d]: 'http-response' expects %s, but got '%s'%s.%s%s%s\n",
file, linenum, trash.area,
args[0], *args[0] ? "" : " (missing argument)",
best ? " Did you mean '" : "",
best ? best : "",
best ? "' maybe ?" : "");
goto out_err;
}
if (strcmp(args[cur_arg], "if") == 0 || strcmp(args[cur_arg], "unless") == 0) {
struct acl_cond *cond;
char *errmsg = NULL;
if ((cond = build_acl_cond(file, linenum, &proxy->acl, proxy, args+cur_arg, &errmsg)) == NULL) {
ha_alert("parsing [%s:%d] : error detected while parsing an 'http-response %s' condition : %s.\n",
file, linenum, args[0], errmsg);
free(errmsg);
goto out_err;
}
rule->cond = cond;
}
else if (*args[cur_arg]) {
ha_alert("parsing [%s:%d]: 'http-response %s' expects"
" either 'if' or 'unless' followed by a condition but found '%s'.\n",
file, linenum, args[0], args[cur_arg]);
goto out_err;
}
return rule;
out_err:
free(rule);
return NULL;
}
/* parse an "http-after-response" rule */
struct act_rule *parse_http_after_res_cond(const char **args, const char *file, int linenum, struct proxy *proxy)
{
struct act_rule *rule;
const struct action_kw *custom = NULL;
int cur_arg;
rule = calloc(1, sizeof(*rule));
if (!rule) {
ha_alert("parsing [%s:%d]: out of memory.\n", file, linenum);
goto out_err;
}
rule->from = ACT_F_HTTP_RES;
if (((custom = action_http_after_res_custom(args[0])) != NULL)) {
char *errmsg = NULL;
cur_arg = 1;
/* try in the module list */
rule->kw = custom;
if (custom->parse(args, &cur_arg, proxy, rule, &errmsg) == ACT_RET_PRS_ERR) {
ha_alert("parsing [%s:%d] : error detected in %s '%s' while parsing 'http-after-response %s' rule : %s.\n",
file, linenum, proxy_type_str(proxy), proxy->id, args[0], errmsg);
free(errmsg);
goto out_err;
}
else if (errmsg) {
ha_warning("parsing [%s:%d] : %s.\n", file, linenum, errmsg);
free(errmsg);
}
}
else {
const char *best = action_suggest(args[0], &http_after_res_keywords.list, NULL);
action_build_list(&http_after_res_keywords.list, &trash);
ha_alert("parsing [%s:%d]: 'http-after-response' expects %s, but got '%s'%s.%s%s%s\n",
file, linenum, trash.area,
args[0], *args[0] ? "" : " (missing argument)",
best ? " Did you mean '" : "",
best ? best : "",
best ? "' maybe ?" : "");
goto out_err;
}
if (strcmp(args[cur_arg], "if") == 0 || strcmp(args[cur_arg], "unless") == 0) {
struct acl_cond *cond;
char *errmsg = NULL;
if ((cond = build_acl_cond(file, linenum, &proxy->acl, proxy, args+cur_arg, &errmsg)) == NULL) {
ha_alert("parsing [%s:%d] : error detected while parsing an 'http-after-response %s' condition : %s.\n",
file, linenum, args[0], errmsg);
free(errmsg);
goto out_err;
}
rule->cond = cond;
}
else if (*args[cur_arg]) {
ha_alert("parsing [%s:%d]: 'http-after-response %s' expects"
" either 'if' or 'unless' followed by a condition but found '%s'.\n",
file, linenum, args[0], args[cur_arg]);
goto out_err;
}
return rule;
out_err:
free(rule);
return NULL;
}
/* Parses a redirect rule. Returns the redirect rule on success or NULL on error,
* with <err> filled with the error message. If <use_fmt> is not null, builds a
* dynamic log-format rule instead of a static string. Parameter <dir> indicates
* the direction of the rule, and equals 0 for request, non-zero for responses.
*/
struct redirect_rule *http_parse_redirect_rule(const char *file, int linenum, struct proxy *curproxy,
const char **args, char **errmsg, int use_fmt, int dir)
{
struct redirect_rule *rule;
int cur_arg;
int type = REDIRECT_TYPE_NONE;
int code = 302;
const char *destination = NULL;
const char *cookie = NULL;
int cookie_set = 0;
unsigned int flags = (!dir ? REDIRECT_FLAG_FROM_REQ : REDIRECT_FLAG_NONE);
struct acl_cond *cond = NULL;
cur_arg = 0;
while (*(args[cur_arg])) {
if (strcmp(args[cur_arg], "location") == 0) {
if (!*args[cur_arg + 1])
goto missing_arg;
type = REDIRECT_TYPE_LOCATION;
cur_arg++;
destination = args[cur_arg];
}
else if (strcmp(args[cur_arg], "prefix") == 0) {
if (!*args[cur_arg + 1])
goto missing_arg;
type = REDIRECT_TYPE_PREFIX;
cur_arg++;
destination = args[cur_arg];
}
else if (strcmp(args[cur_arg], "scheme") == 0) {
if (!*args[cur_arg + 1])
goto missing_arg;
type = REDIRECT_TYPE_SCHEME;
cur_arg++;
destination = args[cur_arg];
}
else if (strcmp(args[cur_arg], "set-cookie") == 0) {
if (!*args[cur_arg + 1])
goto missing_arg;
cur_arg++;
cookie = args[cur_arg];
cookie_set = 1;
}
else if (strcmp(args[cur_arg], "clear-cookie") == 0) {
if (!*args[cur_arg + 1])
goto missing_arg;
cur_arg++;
cookie = args[cur_arg];
cookie_set = 0;
}
else if (strcmp(args[cur_arg], "code") == 0) {
if (!*args[cur_arg + 1])
goto missing_arg;
cur_arg++;
code = atol(args[cur_arg]);
if (code < 301 || code > 308 || (code > 303 && code < 307)) {
memprintf(errmsg,
"'%s': unsupported HTTP code '%s' (must be one of 301, 302, 303, 307 or 308)",
args[cur_arg - 1], args[cur_arg]);
return NULL;
}
}
else if (strcmp(args[cur_arg], "drop-query") == 0) {
flags |= REDIRECT_FLAG_DROP_QS;
}
else if (strcmp(args[cur_arg], "append-slash") == 0) {
flags |= REDIRECT_FLAG_APPEND_SLASH;
}
else if (strcmp(args[cur_arg], "ignore-empty") == 0) {
flags |= REDIRECT_FLAG_IGNORE_EMPTY;
}
else if (strcmp(args[cur_arg], "if") == 0 ||
strcmp(args[cur_arg], "unless") == 0) {
cond = build_acl_cond(file, linenum, &curproxy->acl, curproxy, (const char **)args + cur_arg, errmsg);
if (!cond) {
memprintf(errmsg, "error in condition: %s", *errmsg);
return NULL;
}
break;
}
else {
memprintf(errmsg,
"expects 'code', 'prefix', 'location', 'scheme', 'set-cookie', 'clear-cookie', 'drop-query', 'ignore-empty' or 'append-slash' (was '%s')",
args[cur_arg]);
return NULL;
}
cur_arg++;
}
if (type == REDIRECT_TYPE_NONE) {
memprintf(errmsg, "redirection type expected ('prefix', 'location', or 'scheme')");
return NULL;
}
if (dir && type != REDIRECT_TYPE_LOCATION) {
memprintf(errmsg, "response only supports redirect type 'location'");
return NULL;
}
rule = calloc(1, sizeof(*rule));
if (!rule) {
memprintf(errmsg, "parsing [%s:%d]: out of memory.", file, linenum);
return NULL;
}
rule->cond = cond;
LIST_INIT(&rule->rdr_fmt);
if (!use_fmt) {
/* old-style static redirect rule */
rule->rdr_str = strdup(destination);
rule->rdr_len = strlen(destination);
}
else {
/* log-format based redirect rule */
/* Parse destination. Note that in the REDIRECT_TYPE_PREFIX case,
* if prefix == "/", we don't want to add anything, otherwise it
* makes it hard for the user to configure a self-redirection.
*/
curproxy->conf.args.ctx = ARGC_RDR;
if (!(type == REDIRECT_TYPE_PREFIX && destination[0] == '/' && destination[1] == '\0')) {
if (!parse_logformat_string(destination, curproxy, &rule->rdr_fmt, LOG_OPT_HTTP,
dir ? (curproxy->cap & PR_CAP_FE) ? SMP_VAL_FE_HRS_HDR : SMP_VAL_BE_HRS_HDR
: (curproxy->cap & PR_CAP_FE) ? SMP_VAL_FE_HRQ_HDR : SMP_VAL_BE_HRQ_HDR,
errmsg)) {
return NULL;
}
free(curproxy->conf.lfs_file);
curproxy->conf.lfs_file = strdup(curproxy->conf.args.file);
curproxy->conf.lfs_line = curproxy->conf.args.line;
}
}
if (cookie) {
/* depending on cookie_set, either we want to set the cookie, or to clear it.
* a clear consists in appending "; path=/; Max-Age=0;" at the end.
*/
rule->cookie_len = strlen(cookie);
if (cookie_set) {
rule->cookie_str = malloc(rule->cookie_len + 10);
memcpy(rule->cookie_str, cookie, rule->cookie_len);
memcpy(rule->cookie_str + rule->cookie_len, "; path=/;", 10);
rule->cookie_len += 9;
} else {
rule->cookie_str = malloc(rule->cookie_len + 21);
memcpy(rule->cookie_str, cookie, rule->cookie_len);
memcpy(rule->cookie_str + rule->cookie_len, "; path=/; Max-Age=0;", 21);
rule->cookie_len += 20;
}
}
rule->type = type;
rule->code = code;
rule->flags = flags;
LIST_INIT(&rule->list);
return rule;
missing_arg:
memprintf(errmsg, "missing argument for '%s'", args[cur_arg]);
return NULL;
}
__attribute__((constructor))
static void __http_rules_init(void)
{
}
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/
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