/* Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * mod_headers.c: Add/append/remove HTTP response headers * Written by Paul Sutton, paul@ukweb.com, 1 Oct 1996 * * The Header directive can be used to add/replace/remove HTTP headers * within the response message. The RequestHeader directive can be used * to add/replace/remove HTTP headers before a request message is processed. * Valid in both per-server and per-dir configurations. * * Syntax is: * * Header action header value * RequestHeader action header value * * Where action is one of: * set - set this header, replacing any old value * add - add this header, possible resulting in two or more * headers with the same name * append - append this text onto any existing header of this same * merge - merge this text onto any existing header of this same, * avoiding duplicate values * unset - remove this header * edit - transform the header value according to a regexp * * Where action is unset, the third argument (value) should not be given. * The header name can include the colon, or not. * * The Header and RequestHeader directives can only be used where allowed * by the FileInfo override. * * When the request is processed, the header directives are processed in * this order: firstly, the main server, then the virtual server handling * this request (if any), then any <Directory> sections (working downwards * from the root dir), then an <Location> sections (working down from * shortest URL component), the any <File> sections. This order is * important if any 'set' or 'unset' actions are used. For example, * the following two directives have different effect if applied in * the reverse order: * * Header append Author "John P. Doe" * Header unset Author * * Examples: * * To set the "Author" header, use * Header add Author "John P. Doe" * * To remove a header: * Header unset Author * */ #include "apr.h" #include "apr_lib.h" #include "apr_strings.h" #include "apr_buckets.h" #include "apr_hash.h" #define APR_WANT_STRFUNC #include "apr_want.h" #include "httpd.h" #include "http_config.h" #include "http_request.h" #include "http_log.h" #include "util_filter.h" #include "http_protocol.h" #include "mod_ssl.h" /* for the ssl_var_lookup optional function defn */ /* format_tag_hash is initialized during pre-config */ static apr_hash_t *format_tag_hash; typedef enum { hdr_add = 'a', /* add header (could mean multiple hdrs) */ hdr_set = 's', /* set (replace old value) */ hdr_append = 'm', /* append (merge into any old value) */ hdr_merge = 'g', /* merge (merge, but avoid duplicates) */ hdr_unset = 'u', /* unset header */ hdr_echo = 'e', /* echo headers from request to response */ hdr_edit = 'r' /* change value by regexp */ } hdr_actions; /* * magic cmd->info values */ static char hdr_in = '0'; /* RequestHeader */ static char hdr_out = '1'; /* Header onsuccess */ static char hdr_err = '2'; /* Header always */ /* * There is an array of struct format_tag per Header/RequestHeader * config directive */ typedef struct { const char* (*func)(request_rec *r,char *arg); char *arg; } format_tag; /* 'Magic' condition_var value to run action in post_read_request */ static const char* condition_early = "early"; /* * There is one "header_entry" per Header/RequestHeader config directive */ typedef struct { hdr_actions action; const char *header; apr_array_header_t *ta; /* Array of format_tag structs */ ap_regex_t *regex; const char *condition_var; const char *subs; } header_entry; /* echo_do is used for Header echo to iterate through the request headers*/ typedef struct { request_rec *r; header_entry *hdr; } echo_do; /* edit_do is used for Header edit to iterate through the request headers */ typedef struct { apr_pool_t *p; header_entry *hdr; apr_table_t *t; } edit_do; /* * headers_conf is our per-module configuration. This is used as both * a per-dir and per-server config */ typedef struct { apr_array_header_t *fixup_in; apr_array_header_t *fixup_out; apr_array_header_t *fixup_err; } headers_conf; module AP_MODULE_DECLARE_DATA headers_module; /* Pointer to ssl_var_lookup, if available. */ static APR_OPTIONAL_FN_TYPE(ssl_var_lookup) *header_ssl_lookup = NULL; /* * Tag formatting functions */ static const char *constant_item(request_rec *r, char *stuff) { return stuff; } static const char *header_request_duration(request_rec *r, char *a) { return apr_psprintf(r->pool, "D=%" APR_TIME_T_FMT, (apr_time_now() - r->request_time)); } static const char *header_request_time(request_rec *r, char *a) { return apr_psprintf(r->pool, "t=%" APR_TIME_T_FMT, r->request_time); } /* unwrap_header returns HDR with any newlines converted into * whitespace if necessary. */ static const char *unwrap_header(apr_pool_t *p, const char *hdr) { if (ap_strchr_c(hdr, APR_ASCII_LF) || ap_strchr_c(hdr, APR_ASCII_CR)) { char *ptr; hdr = ptr = apr_pstrdup(p, hdr); do { if (*ptr == APR_ASCII_LF || *ptr == APR_ASCII_CR) *ptr = APR_ASCII_BLANK; } while (*ptr++); } return hdr; } static const char *header_request_env_var(request_rec *r, char *a) { const char *s = apr_table_get(r->subprocess_env,a); if (s) return unwrap_header(r->pool, s); else return "(null)"; } static const char *header_request_ssl_var(request_rec *r, char *name) { if (header_ssl_lookup) { const char *val = header_ssl_lookup(r->pool, r->server, r->connection, r, name); if (val && val[0]) return unwrap_header(r->pool, val); else return "(null)"; } else { return "(null)"; } } /* * Config routines */ static void *create_headers_dir_config(apr_pool_t *p, char *d) { headers_conf *conf = apr_pcalloc(p, sizeof(*conf)); conf->fixup_in = apr_array_make(p, 2, sizeof(header_entry)); conf->fixup_out = apr_array_make(p, 2, sizeof(header_entry)); conf->fixup_err = apr_array_make(p, 2, sizeof(header_entry)); return conf; } static void *merge_headers_config(apr_pool_t *p, void *basev, void *overridesv) { headers_conf *newconf = apr_pcalloc(p, sizeof(*newconf)); headers_conf *base = basev; headers_conf *overrides = overridesv; newconf->fixup_in = apr_array_append(p, base->fixup_in, overrides->fixup_in); newconf->fixup_out = apr_array_append(p, base->fixup_out, overrides->fixup_out); newconf->fixup_err = apr_array_append(p, base->fixup_err, overrides->fixup_err); return newconf; } static char *parse_misc_string(apr_pool_t *p, format_tag *tag, const char **sa) { const char *s; char *d; tag->func = constant_item; s = *sa; while (*s && *s != '%') { s++; } /* * This might allocate a few chars extra if there's a backslash * escape in the format string. */ tag->arg = apr_palloc(p, s - *sa + 1); d = tag->arg; s = *sa; while (*s && *s != '%') { if (*s != '\\') { *d++ = *s++; } else { s++; switch (*s) { case '\\': *d++ = '\\'; s++; break; case 'r': *d++ = '\r'; s++; break; case 'n': *d++ = '\n'; s++; break; case 't': *d++ = '\t'; s++; break; default: /* copy verbatim */ *d++ = '\\'; /* * Allow the loop to deal with this *s in the normal * fashion so that it handles end of string etc. * properly. */ break; } } } *d = '\0'; *sa = s; return NULL; } static char *parse_format_tag(apr_pool_t *p, format_tag *tag, const char **sa) { const char *s = *sa; const char * (*tag_handler)(request_rec *,char *); /* Handle string literal/conditionals */ if (*s != '%') { return parse_misc_string(p, tag, sa); } s++; /* skip the % */ /* Pass through %% or % at end of string as % */ if ((*s == '%') || (*s == '\0')) { tag->func = constant_item; tag->arg = "%"; if (*s) s++; *sa = s; return NULL; } tag->arg = '\0'; /* grab the argument if there is one */ if (*s == '{') { ++s; tag->arg = ap_getword(p,&s,'}'); } tag_handler = (const char * (*)(request_rec *,char *))apr_hash_get(format_tag_hash, s++, 1); if (!tag_handler) { char dummy[2]; dummy[0] = s[-1]; dummy[1] = '\0'; return apr_pstrcat(p, "Unrecognized header format %", dummy, NULL); } tag->func = tag_handler; *sa = s; return NULL; } /* * A format string consists of white space, text and optional format * tags in any order. E.g., * * Header add MyHeader "Free form text %D %t more text" * * Decompose the format string into its tags. Each tag (struct format_tag) * contains a pointer to the function used to format the tag. Then save each * tag in the tag array anchored in the header_entry. */ static char *parse_format_string(apr_pool_t *p, header_entry *hdr, const char *s) { char *res; /* No string to parse with unset and echo commands */ if (hdr->action == hdr_unset || hdr->action == hdr_edit || hdr->action == hdr_echo) { return NULL; } hdr->ta = apr_array_make(p, 10, sizeof(format_tag)); while (*s) { if ((res = parse_format_tag(p, (format_tag *) apr_array_push(hdr->ta), &s))) { return res; } } return NULL; } /* handle RequestHeader and Header directive */ static APR_INLINE const char *header_inout_cmd(cmd_parms *cmd, void *indirconf, const char *action, const char *hdr, const char *value, const char *subs, const char *envclause) { headers_conf *dirconf = indirconf; const char *condition_var = NULL; const char *colon; header_entry *new; apr_array_header_t *fixup = (cmd->info == &hdr_in) ? dirconf->fixup_in : (cmd->info == &hdr_err) ? dirconf->fixup_err : dirconf->fixup_out; new = (header_entry *) apr_array_push(fixup); if (!strcasecmp(action, "set")) new->action = hdr_set; else if (!strcasecmp(action, "add")) new->action = hdr_add; else if (!strcasecmp(action, "append")) new->action = hdr_append; else if (!strcasecmp(action, "merge")) new->action = hdr_merge; else if (!strcasecmp(action, "unset")) new->action = hdr_unset; else if (!strcasecmp(action, "echo")) new->action = hdr_echo; else if (!strcasecmp(action, "edit")) new->action = hdr_edit; else return "first argument must be 'add', 'set', 'append', 'merge', " "'unset', 'echo', or 'edit'."; if (new->action == hdr_edit) { if (subs == NULL) { return "Header edit requires a match and a substitution"; } new->regex = ap_pregcomp(cmd->pool, value, AP_REG_EXTENDED); if (new->regex == NULL) { return "Header edit regex could not be compiled"; } new->subs = subs; } else { /* there's no subs, so envclause is really that argument */ if (envclause != NULL) { return "Too many arguments to directive"; } envclause = subs; } if (new->action == hdr_unset) { if (value) { if (envclause) { return "header unset takes two arguments"; } envclause = value; value = NULL; } } else if (new->action == hdr_echo) { ap_regex_t *regex; if (value) { if (envclause) { return "Header echo takes two arguments"; } envclause = value; value = NULL; } if (cmd->info != &hdr_out && cmd->info != &hdr_err) return "Header echo only valid on Header " "directives"; else { regex = ap_pregcomp(cmd->pool, hdr, AP_REG_EXTENDED | AP_REG_NOSUB); if (regex == NULL) { return "Header echo regex could not be compiled"; } } new->regex = regex; } else if (!value) return "Header requires three arguments"; /* Handle the envclause on Header */ if (envclause != NULL) { if (strcasecmp(envclause, "early") == 0) { condition_var = condition_early; } else { if (strncasecmp(envclause, "env=", 4) != 0) { return "error: envclause should be in the form env=envar"; } if ((envclause[4] == '\0') || ((envclause[4] == '!') && (envclause[5] == '\0'))) { return "error: missing environment variable name. " "envclause should be in the form env=envar "; } condition_var = envclause + 4; } } if ((colon = ap_strchr_c(hdr, ':'))) { hdr = apr_pstrmemdup(cmd->pool, hdr, colon-hdr); } new->header = hdr; new->condition_var = condition_var; return parse_format_string(cmd->pool, new, value); } /* Handle all (xxx)Header directives */ static const char *header_cmd(cmd_parms *cmd, void *indirconf, const char *args) { const char *action; const char *hdr; const char *val; const char *envclause; const char *subs; action = ap_getword_conf(cmd->pool, &args); if (cmd->info == &hdr_out) { if (!strcasecmp(action, "always")) { cmd->info = &hdr_err; action = ap_getword_conf(cmd->pool, &args); } else if (!strcasecmp(action, "onsuccess")) { action = ap_getword_conf(cmd->pool, &args); } } hdr = ap_getword_conf(cmd->pool, &args); val = *args ? ap_getword_conf(cmd->pool, &args) : NULL; subs = *args ? ap_getword_conf(cmd->pool, &args) : NULL; envclause = *args ? ap_getword_conf(cmd->pool, &args) : NULL; if (*args) { return apr_pstrcat(cmd->pool, cmd->cmd->name, " has too many arguments", NULL); } return header_inout_cmd(cmd, indirconf, action, hdr, val, subs, envclause); } /* * Process the tags in the format string. Tags may be format specifiers * (%D, %t, etc.), whitespace or text strings. For each tag, run the handler * (formatter) specific to the tag. Handlers return text strings. * Concatenate the return from each handler into one string that is * returned from this call. */ static char* process_tags(header_entry *hdr, request_rec *r) { int i; const char *s; char *str = NULL; format_tag *tag = (format_tag*) hdr->ta->elts; for (i = 0; i < hdr->ta->nelts; i++) { s = tag[i].func(r, tag[i].arg); if (str == NULL) str = apr_pstrdup(r->pool, s); else str = apr_pstrcat(r->pool, str, s, NULL); } return str ? str : ""; } static const char *process_regexp(header_entry *hdr, const char *value, apr_pool_t *pool) { unsigned int nmatch = 10; ap_regmatch_t pmatch[10]; const char *subs; char *ret; int diffsz; if (ap_regexec(hdr->regex, value, nmatch, pmatch, 0)) { /* no match, nothing to do */ return value; } subs = ap_pregsub(pool, hdr->subs, value, nmatch, pmatch); diffsz = strlen(subs) - (pmatch[0].rm_eo - pmatch[0].rm_so); ret = apr_palloc(pool, strlen(value) + 1 + diffsz); memcpy(ret, value, pmatch[0].rm_so); strcpy(ret + pmatch[0].rm_so, subs); strcat(ret, value + pmatch[0].rm_eo); return ret; } static int echo_header(echo_do *v, const char *key, const char *val) { /* If the input header (key) matches the regex, echo it intact to * r->headers_out. */ if (!ap_regexec(v->hdr->regex, key, 0, NULL, 0)) { apr_table_add(v->r->headers_out, key, val); } return 1; } static int edit_header(void *v, const char *key, const char *val) { edit_do *ed = (edit_do *)v; apr_table_addn(ed->t, key, process_regexp(ed->hdr, val, ed->p)); return 1; } static int add_them_all(void *v, const char *key, const char *val) { apr_table_t *headers = (apr_table_t *)v; apr_table_addn(headers, key, val); return 1; } static void do_headers_fixup(request_rec *r, apr_table_t *headers, apr_array_header_t *fixup, int early) { echo_do v; int i; const char *val; for (i = 0; i < fixup->nelts; ++i) { header_entry *hdr = &((header_entry *) (fixup->elts))[i]; const char *envar = hdr->condition_var; /* ignore early headers in late calls */ if (!early && (envar == condition_early)) { continue; } /* ignore late headers in early calls */ else if (early && (envar != condition_early)) { continue; } /* Have any conditional envar-controlled Header processing to do? */ else if (envar && !early) { if (*envar != '!') { if (apr_table_get(r->subprocess_env, envar) == NULL) continue; } else { if (apr_table_get(r->subprocess_env, &envar[1]) != NULL) continue; } } switch (hdr->action) { case hdr_add: apr_table_addn(headers, hdr->header, process_tags(hdr, r)); break; case hdr_append: apr_table_mergen(headers, hdr->header, process_tags(hdr, r)); break; case hdr_merge: val = apr_table_get(headers, hdr->header); if (val == NULL) { apr_table_addn(headers, hdr->header, process_tags(hdr, r)); } else { char *new_val = process_tags(hdr, r); apr_size_t new_val_len = strlen(new_val); int tok_found = 0; /* modified version of logic in ap_get_token() */ while (*val) { const char *tok_start; while (*val && apr_isspace(*val)) ++val; tok_start = val; while (*val && *val != ',') { if (*val++ == '"') while (*val) if (*val++ == '"') break; } if (new_val_len == (apr_size_t)(val - tok_start) && !strncmp(tok_start, new_val, new_val_len)) { tok_found = 1; break; } if (*val) ++val; } if (!tok_found) { apr_table_mergen(headers, hdr->header, new_val); } } break; case hdr_set: apr_table_setn(headers, hdr->header, process_tags(hdr, r)); break; case hdr_unset: apr_table_unset(headers, hdr->header); break; case hdr_echo: v.r = r; v.hdr = hdr; apr_table_do((int (*) (void *, const char *, const char *)) echo_header, (void *) &v, r->headers_in, NULL); break; case hdr_edit: if (apr_table_get(headers, hdr->header)) { edit_do ed; ed.p = r->pool; ed.hdr = hdr; ed.t = apr_table_make(r->pool, 5); apr_table_do(edit_header, (void *) &ed, headers, hdr->header, NULL); apr_table_unset(headers, hdr->header); apr_table_do(add_them_all, (void *) headers, ed.t, NULL); } break; } } } static void ap_headers_insert_output_filter(request_rec *r) { headers_conf *dirconf = ap_get_module_config(r->per_dir_config, &headers_module); if (dirconf->fixup_out->nelts || dirconf->fixup_err->nelts) { ap_add_output_filter("FIXUP_HEADERS_OUT", NULL, r, r->connection); } } /* * Make sure our error-path filter is in place. */ static void ap_headers_insert_error_filter(request_rec *r) { headers_conf *dirconf = ap_get_module_config(r->per_dir_config, &headers_module); if (dirconf->fixup_err->nelts) { ap_add_output_filter("FIXUP_HEADERS_ERR", NULL, r, r->connection); } } static apr_status_t ap_headers_output_filter(ap_filter_t *f, apr_bucket_brigade *in) { headers_conf *dirconf = ap_get_module_config(f->r->per_dir_config, &headers_module); ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, f->r->server, "headers: ap_headers_output_filter()"); /* do the fixup */ do_headers_fixup(f->r, f->r->err_headers_out, dirconf->fixup_err, 0); do_headers_fixup(f->r, f->r->headers_out, dirconf->fixup_out, 0); /* remove ourselves from the filter chain */ ap_remove_output_filter(f); /* send the data up the stack */ return ap_pass_brigade(f->next,in); } /* * Make sure we propagate any "Header always" settings on the error * path through http_protocol.c. */ static apr_status_t ap_headers_error_filter(ap_filter_t *f, apr_bucket_brigade *in) { headers_conf *dirconf; dirconf = ap_get_module_config(f->r->per_dir_config, &headers_module); ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, f->r->server, "headers: ap_headers_error_filter()"); /* * Add any header fields defined by "Header always" to r->err_headers_out. * Server-wide first, then per-directory to allow overriding. */ do_headers_fixup(f->r, f->r->err_headers_out, dirconf->fixup_err, 0); /* * We've done our bit; remove ourself from the filter chain so there's * no possibility we'll be called again. */ ap_remove_output_filter(f); /* * Pass the buck. (euro?) */ return ap_pass_brigade(f->next, in); } static apr_status_t ap_headers_fixup(request_rec *r) { headers_conf *dirconf = ap_get_module_config(r->per_dir_config, &headers_module); /* do the fixup */ if (dirconf->fixup_in->nelts) { do_headers_fixup(r, r->headers_in, dirconf->fixup_in, 0); } return DECLINED; } static apr_status_t ap_headers_early(request_rec *r) { headers_conf *dirconf = ap_get_module_config(r->per_dir_config, &headers_module); /* do the fixup */ if (dirconf->fixup_in->nelts) { do_headers_fixup(r, r->headers_in, dirconf->fixup_in, 1); } if (dirconf->fixup_err->nelts) { do_headers_fixup(r, r->err_headers_out, dirconf->fixup_err, 1); } if (dirconf->fixup_out->nelts) { do_headers_fixup(r, r->headers_out, dirconf->fixup_out, 1); } return DECLINED; } static const command_rec headers_cmds[] = { AP_INIT_RAW_ARGS("Header", header_cmd, &hdr_out, OR_FILEINFO, "an optional condition, an action, header and value " "followed by optional env clause"), AP_INIT_RAW_ARGS("RequestHeader", header_cmd, &hdr_in, OR_FILEINFO, "an action, header and value followed by optional env " "clause"), {NULL} }; static void register_format_tag_handler(const char *tag, const void *tag_handler) { apr_hash_set(format_tag_hash, tag, 1, tag_handler); } static int header_pre_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp) { format_tag_hash = apr_hash_make(p); register_format_tag_handler("D", (const void *)header_request_duration); register_format_tag_handler("t", (const void *)header_request_time); register_format_tag_handler("e", (const void *)header_request_env_var); register_format_tag_handler("s", (const void *)header_request_ssl_var); return OK; } static int header_post_config(apr_pool_t *pconf, apr_pool_t *plog, apr_pool_t *ptemp, server_rec *s) { header_ssl_lookup = APR_RETRIEVE_OPTIONAL_FN(ssl_var_lookup); return OK; } static void register_hooks(apr_pool_t *p) { ap_register_output_filter("FIXUP_HEADERS_OUT", ap_headers_output_filter, NULL, AP_FTYPE_CONTENT_SET); ap_register_output_filter("FIXUP_HEADERS_ERR", ap_headers_error_filter, NULL, AP_FTYPE_CONTENT_SET); ap_hook_pre_config(header_pre_config,NULL,NULL,APR_HOOK_MIDDLE); ap_hook_post_config(header_post_config,NULL,NULL,APR_HOOK_MIDDLE); ap_hook_insert_filter(ap_headers_insert_output_filter, NULL, NULL, APR_HOOK_LAST); ap_hook_insert_error_filter(ap_headers_insert_error_filter, NULL, NULL, APR_HOOK_LAST); ap_hook_fixups(ap_headers_fixup, NULL, NULL, APR_HOOK_LAST); ap_hook_post_read_request(ap_headers_early, NULL, NULL, APR_HOOK_FIRST); } module AP_MODULE_DECLARE_DATA headers_module = { STANDARD20_MODULE_STUFF, create_headers_dir_config, /* dir config creater */ merge_headers_config, /* dir merger --- default is to override */ NULL, /* server config */ NULL, /* merge server configs */ headers_cmds, /* command apr_table_t */ register_hooks /* register hooks */ };
.htaccess Tutorial
Find information you are looking for on the AskApache Home Page.