mod_headers.c

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

                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 */
};