Quelle proxy_util.c Sprache: C

/* 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.
*/

/* Utility routines for Apache proxy */
#include "mod_proxy.h"
#include "ap_mpm.h"
#include "scoreboard.h"
#include "apr_version.h"
#include "apr_strings.h"
#include "apr_hash.h"
#include "apr_atomic.h"
#include "http_core.h"
#include "proxy_util.h"
#include "ajp.h"
#include "scgi.h"

#include "mpm_common.h" /* for ap_max_mem_free */

#include "mod_http2.h" /* for http2_get_num_workers() */

#if APR_HAVE_UNISTD_H
#include <unistd.h>         /* for getpid() */
#endif

#if APR_HAVE_SYS_UN_H
#include <sys/un.h>
#endif
#if (APR_MAJOR_VERSION < 2)
#include "apr_support.h"        /* for apr_wait_for_io_or_timeout() */
#endif

APLOG_USE_MODULE(proxy);

/*
* Opaque structure containing infos for CONNECT-ing an origin server through a
* remote (forward) proxy. Saved in the (opaque) proxy_conn_rec::forward pointer
* field for backend connections kept alive, allowing for reuse when subsequent
* requests should be routed through the same remote proxy.
*/
typedef struct {
    const char   *proxy_auth;      /* Proxy authorization */
    const char   *target_host;     /* Target/origin hostname */
    apr_port_t   target_port;      /* Target/origin port */
} remote_connect_info;

/*
* Opaque structure containing a refcounted and TTL'ed address.
*/
typedef struct proxy_address {
    apr_sockaddr_t *addr;       /* Remote address info */
    const char *hostname;       /* Remote host name */
    apr_port_t hostport;        /* Remote host port */
    apr_uint32_t refcount;      /* Number of conns and/or worker using it */
    apr_uint32_t expiry;        /* Expiry timestamp (seconds to proxy_start_time) */
} proxy_address;

/* Global balancer counter */
int PROXY_DECLARE_DATA proxy_lb_workers = 0;
static int lb_workers_limit = 0;
const apr_strmatch_pattern PROXY_DECLARE_DATA *ap_proxy_strmatch_path;
const apr_strmatch_pattern PROXY_DECLARE_DATA *ap_proxy_strmatch_domain;

extern apr_global_mutex_t *proxy_mutex;

static const apr_time_t *proxy_start_time; /* epoch for expiring addresses */

static int proxy_match_ipaddr(struct dirconn_entry *This, request_rec *r);
static int proxy_match_domainname(struct dirconn_entry *This, request_rec *r);
static int proxy_match_hostname(struct dirconn_entry *This, request_rec *r);
static int proxy_match_word(struct dirconn_entry *This, request_rec *r);
static int ap_proxy_retry_worker(const char *proxy_function, proxy_worker *worker, server_rec *s);
static proxy_worker *proxy_balancer_get_best_worker(proxy_balancer *balancer,
                                                    request_rec *r,
                                                    proxy_is_best_callback_fn_t *is_best,
                                                    void *baton);

APR_IMPLEMENT_OPTIONAL_HOOK_RUN_ALL(proxy, PROXY, int, create_req,
                                   (request_rec *r, request_rec *pr), (r, pr),
                                   OK, DECLINED)

PROXY_DECLARE(apr_status_t) ap_proxy_strncpy(char *dst, const char *src,
                                             apr_size_t dlen)
{
    char *thenil;
    apr_size_t thelen;

    /* special case handling */
    if (!dlen) {
        /* XXX: APR_ENOSPACE would be better */
        return APR_EGENERAL;
    }
    if (!src) {
        *dst = '\0';
        return APR_SUCCESS;
    }
    thenil = apr_cpystrn(dst, src, dlen);
    thelen = thenil - dst;
    if (src[thelen] == '\0') {
        return APR_SUCCESS;
    }
    return APR_EGENERAL;
}

/* already called in the knowledge that the characters are hex digits */
PROXY_DECLARE(int) ap_proxy_hex2c(const char *x)
{
    int i;

#if !APR_CHARSET_EBCDIC
    int ch = x[0];

    if (apr_isdigit(ch)) {
        i = ch - '0';
    }
    else if (apr_isupper(ch)) {
        i = ch - ('A' - 10);
    }
    else {
        i = ch - ('a' - 10);
    }
    i <<= 4;

    ch = x[1];
    if (apr_isdigit(ch)) {
        i += ch - '0';
    }
    else if (apr_isupper(ch)) {
        i += ch - ('A' - 10);
    }
    else {
        i += ch - ('a' - 10);
    }
    return i;
#else /*APR_CHARSET_EBCDIC*/
    /*
     * we assume that the hex value refers to an ASCII character
     * so convert to EBCDIC so that it makes sense locally;
     *
     * example:
     *
     * client specifies %20 in URL to refer to a space char;
     * at this point we're called with EBCDIC "20"; after turning
     * EBCDIC "20" into binary 0x20, we then need to assume that 0x20
     * represents an ASCII char and convert 0x20 to EBCDIC, yielding
     * 0x40
     */
    char buf[1];

    if (1 == sscanf(x, "%2x", &i)) {
        buf[0] = i & 0xFF;
        ap_xlate_proto_from_ascii(buf, 1);
        return buf[0];
    }
    else {
        return 0;
    }
#endif /*APR_CHARSET_EBCDIC*/
}

PROXY_DECLARE(void) ap_proxy_c2hex(int ch, char *x)
{
#if !APR_CHARSET_EBCDIC
    int i;

    x[0] = '%';
    i = (ch & 0xF0) >> 4;
    if (i >= 10) {
        x[1] = ('A' - 10) + i;
    }
    else {
        x[1] = '0' + i;
    }

    i = ch & 0x0F;
    if (i >= 10) {
        x[2] = ('A' - 10) + i;
    }
    else {
        x[2] = '0' + i;
    }
#else /*APR_CHARSET_EBCDIC*/
    static const char ntoa[] = { "0123456789ABCDEF" };
    char buf[1];

    ch &= 0xFF;

    buf[0] = ch;
    ap_xlate_proto_to_ascii(buf, 1);

    x[0] = '%';
    x[1] = ntoa[(buf[0] >> 4) & 0x0F];
    x[2] = ntoa[buf[0] & 0x0F];
    x[3] = '\0';
#endif /*APR_CHARSET_EBCDIC*/
}

/*
* canonicalise a URL-encoded string
*/

/*
* Convert a URL-encoded string to canonical form.
* It decodes characters which need not be encoded,
* and encodes those which must be encoded, and does not touch
* those which must not be touched.
*/
PROXY_DECLARE(char *)ap_proxy_canonenc_ex(apr_pool_t *p, const char *x, int len,
                                          enum enctype t, int flags,
                                          int proxyreq)
{
    int i, j, ch;
    char *y;
    char *allowed;  /* characters which should not be encoded */
    char *reserved; /* characters which much not be en/de-coded */
    int forcedec = flags & PROXY_CANONENC_FORCEDEC;
    int noencslashesenc = flags & PROXY_CANONENC_NOENCODEDSLASHENCODING;

/*
* N.B. in addition to :@&=, this allows ';' in an http path
* and '?' in an ftp path -- this may be revised
*
* Also, it makes a '+' character in a search string reserved, as
* it may be form-encoded. (Although RFC 1738 doesn't allow this -
* it only permits ; / ? : @ = & as reserved chars.)
*/
    if (t == enc_path) {
        allowed = "~$-_.+!*'(),;:@&=";
    }
    else if (t == enc_search) {
        allowed = "$-_.!*'(),;:@&=";
    }
    else if (t == enc_user) {
        allowed = "$-_.+!*'(),;@&=";
    }
    else if (t == enc_fpath) {
        allowed = "$-_.+!*'(),?:@&=";
    }
    else {            /* if (t == enc_parm) */
        allowed = "$-_.+!*'(),?/:@&=";
    }

    if (t == enc_path) {
        reserved = "/";
    }
    else if (t == enc_search) {
        reserved = "+";
    }
    else {
        reserved = "";
    }

    y = apr_palloc(p, 3 * len + 1);

    for (i = 0, j = 0; i < len; i++, j++) {
/* always handle '/' first */
        ch = x[i];
        if (strchr(reserved, ch)) {
            y[j] = ch;
            continue;
        }
/*
* decode it if not already done. do not decode reverse proxied URLs
* unless specifically forced
*/
        if ((forcedec || noencslashesenc
            || (proxyreq && proxyreq != PROXYREQ_REVERSE)) && ch == '%') {
            if (!apr_isxdigit(x[i + 1]) || !apr_isxdigit(x[i + 2])) {
                return NULL;
            }
            ch = ap_proxy_hex2c(&x[i + 1]);
            if (ch != 0 && strchr(reserved, ch)) {  /* keep it encoded */
                y[j++] = x[i++];
                y[j++] = x[i++];
                y[j] = x[i];
                continue;
            }
            if (noencslashesenc && !forcedec && (proxyreq == PROXYREQ_REVERSE)) {
                /*
                 * In the reverse proxy case when we only want to keep encoded
                 * slashes untouched revert back to '%' which will cause
                 * '%' to be encoded in the following.
                 */
                ch = '%';
            }
            else {
                i += 2;
            }
        }
/* recode it, if necessary */
        if (!apr_isalnum(ch) && !strchr(allowed, ch)) {
            ap_proxy_c2hex(ch, &y[j]);
            j += 2;
        }
        else {
            y[j] = ch;
        }
    }
    y[j] = '\0';
    return y;
}

/*
* Convert a URL-encoded string to canonical form.
* It decodes characters which need not be encoded,
* and encodes those which must be encoded, and does not touch
* those which must not be touched.
*/
PROXY_DECLARE(char *)ap_proxy_canonenc(apr_pool_t *p, const char *x, int len,
                                       enum enctype t, int forcedec,
                                       int proxyreq)
{
    int flags;

    flags = forcedec ? PROXY_CANONENC_FORCEDEC : 0;
    return ap_proxy_canonenc_ex(p, x, len, t, flags, proxyreq);
}

/*
* Parses network-location.
*    urlp           on input the URL; on output the path, after the leading /
*    user           NULL if no user/password permitted
*    password       holder for password
*    host           holder for host
*    port           port number; only set if one is supplied.
*
* Returns an error string.
*/
PROXY_DECLARE(char *)
     ap_proxy_canon_netloc(apr_pool_t *p, char **const urlp, char **userp,
            char **passwordp, char **hostp, apr_port_t *port)
{
    char *addr, *scope_id, *strp, *host, *url = *urlp;
    char *user = NULL, *password = NULL;
    apr_port_t tmp_port;
    apr_status_t rv;

    if (url[0] != '/' || url[1] != '/') {
        return "Malformed URL";
    }
    host = url + 2;
    url = strchr(host, '/');
    if (url == NULL) {
        url = "";
    }
    else {
        *(url++) = '\0';    /* skip separating '/' */
    }

    /* find _last_ '@' since it might occur in user/password part */
    strp = strrchr(host, '@');

    if (strp != NULL) {
        *strp = '\0';
        user = host;
        host = strp + 1;

/* find password */
        strp = strchr(user, ':');
        if (strp != NULL) {
            *strp = '\0';
            password = ap_proxy_canonenc(p, strp + 1, strlen(strp + 1), enc_user, 1, 0);
            if (password == NULL) {
                return "Bad %-escape in URL (password)";
            }
        }

        user = ap_proxy_canonenc(p, user, strlen(user), enc_user, 1, 0);
        if (user == NULL) {
            return "Bad %-escape in URL (username)";
        }
    }
    if (userp != NULL) {
        *userp = user;
    }
    if (passwordp != NULL) {
        *passwordp = password;
    }

    /*
     * Parse the host string to separate host portion from optional port.
     * Perform range checking on port.
     */
    rv = apr_parse_addr_port(&addr, &scope_id, &tmp_port, host, p);
    if (rv != APR_SUCCESS || addr == NULL || scope_id != NULL) {
        return "Invalid host/port";
    }
    if (tmp_port != 0) { /* only update caller's port if port was specified */
        *port = tmp_port;
    }

    ap_str_tolower(addr); /* DNS names are case-insensitive */

    *urlp = url;
    *hostp = addr;

    return NULL;
}

static int proxyerror_core(request_rec *r, int statuscode, const char *message,
                           apr_status_t rv)
{
    ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(00898)
                  "%s returned by %s", message, r->uri);

    apr_table_setn(r->notes, "error-notes",
        apr_pstrcat(r->pool,
            "The proxy server could not handle the request

"
"Reason: ", ap_escape_html(r->pool, message),
"

",
            NULL));

    /* Allow "error-notes" string to be printed by ap_send_error_response() */
    apr_table_setn(r->notes, "verbose-error-to", "*");

    r->status_line = apr_psprintf(r->pool, "%3.3u Proxy Error", statuscode);
    return statuscode;
}

PROXY_DECLARE(int) ap_proxyerror(request_rec *r, int statuscode, const char *message)
{
    return proxyerror_core(r, statuscode, message, 0);
}

static const char *
     proxy_get_host_of_request(request_rec *r)
{
    char *url, *user = NULL, *password = NULL, *err, *host = NULL;
    apr_port_t port;

    if (r->hostname != NULL) {
        return r->hostname;
    }

    /* Set url to the first char after "scheme://" */
    if ((url = strchr(r->uri, ':')) == NULL || url[1] != '/' || url[2] != '/') {
        return NULL;
    }

    url = apr_pstrdup(r->pool, &url[1]);    /* make it point to "//", which is what proxy_canon_netloc expects */

    err = ap_proxy_canon_netloc(r->pool, &url, &user, &password, &host, &port);

    if (err != NULL) {
        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00899) "%s", err);
    }

    r->hostname = host;

    return host;        /* ought to return the port, too */
}

/* Return TRUE if addr represents an IP address (or an IP network address) */
PROXY_DECLARE(int) ap_proxy_is_ipaddr(struct dirconn_entry *This, apr_pool_t *p)
{
    const char *addr = This->name;
    long ip_addr[4];
    int i, quads;
    long bits;

    /*
     * if the address is given with an explicit netmask, use that
     * Due to a deficiency in apr_inet_addr(), it is impossible to parse
     * "partial" addresses (with less than 4 quads) correctly, i.e.
     * 192.168.123 is parsed as 192.168.0.123, which is not what I want.
     * I therefore have to parse the IP address manually:
     * if (proxy_readmask(This->name, &This->addr.s_addr, &This->mask.s_addr) == 0)
     * addr and mask were set by proxy_readmask()
     * return 1;
     */

    /*
     * Parse IP addr manually, optionally allowing
     * abbreviated net addresses like 192.168.
     */

    /* Iterate over up to 4 (dotted) quads. */
    for (quads = 0; quads < 4 && *addr != '\0'; ++quads) {
        char *tmp;

        if (*addr == '/' && quads > 0) {  /* netmask starts here. */
            break;
        }

        if (!apr_isdigit(*addr)) {
            return 0;       /* no digit at start of quad */
        }

        ip_addr[quads] = strtol(addr, &tmp, 0);

        if (tmp == addr) {  /* expected a digit, found something else */
            return 0;
        }

        if (ip_addr[quads] < 0 || ip_addr[quads] > 255) {
            /* invalid octet */
            return 0;
        }

        addr = tmp;

        if (*addr == '.' && quads != 3) {
            ++addr;     /* after the 4th quad, a dot would be illegal */
        }
    }

    for (This->addr.s_addr = 0, i = 0; i < quads; ++i) {
        This->addr.s_addr |= htonl(ip_addr[i] << (24 - 8 * i));
    }

    if (addr[0] == '/' && apr_isdigit(addr[1])) {   /* net mask follows: */
        char *tmp;

        ++addr;

        bits = strtol(addr, &tmp, 0);

        if (tmp == addr) {   /* expected a digit, found something else */
            return 0;
        }

        addr = tmp;

        if (bits < 0 || bits > 32) { /* netmask must be between 0 and 32 */
            return 0;
        }

    }
    else {
        /*
         * Determine (i.e., "guess") netmask by counting the
         * number of trailing .0's; reduce #quads appropriately
         * (so that 192.168.0.0 is equivalent to 192.168.)
         */
        while (quads > 0 && ip_addr[quads - 1] == 0) {
            --quads;
        }

        /* "IP Address should be given in dotted-quad form, optionally followed by a netmask (e.g., 192.168.111.0/24)"; */
        if (quads < 1) {
            return 0;
        }

        /* every zero-byte counts as 8 zero-bits */
        bits = 8 * quads;

        if (bits != 32) {     /* no warning for fully qualified IP address */
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00900)
                         "Warning: NetMask not supplied with IP-Addr; guessing: %s/%ld",
                         inet_ntoa(This->addr), bits);
        }
    }

    This->mask.s_addr = htonl(APR_INADDR_NONE << (32 - bits));

    if (*addr == '\0' && (This->addr.s_addr & ~This->mask.s_addr) != 0) {
        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00901)
                     "Warning: NetMask and IP-Addr disagree in %s/%ld",
                     inet_ntoa(This->addr), bits);
        This->addr.s_addr &= This->mask.s_addr;
        ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00902)
                     " Set to %s/%ld", inet_ntoa(This->addr), bits);
    }

    if (*addr == '\0') {
        This->matcher = proxy_match_ipaddr;
        return 1;
    }
    else {
        return (*addr == '\0'); /* okay iff we've parsed the whole string */
    }
}

/* Return TRUE if addr represents an IP address (or an IP network address) */
static int proxy_match_ipaddr(struct dirconn_entry *This, request_rec *r)
{
    int i, ip_addr[4];
    struct in_addr addr, *ip;
    const char *host = proxy_get_host_of_request(r);

    if (host == NULL) {   /* oops! */
       return 0;
    }

    memset(&addr, '\0', sizeof addr);
    memset(ip_addr, '\0', sizeof ip_addr);

    if (4 == sscanf(host, "%d.%d.%d.%d", &ip_addr[0], &ip_addr[1], &ip_addr[2], &ip_addr[3])) {
        for (addr.s_addr = 0, i = 0; i < 4; ++i) {
            /* ap_proxy_is_ipaddr() already confirmed that we have
             * a valid octet in ip_addr[i]
             */
            addr.s_addr |= htonl(ip_addr[i] << (24 - 8 * i));
        }

        if (This->addr.s_addr == (addr.s_addr & This->mask.s_addr)) {
#if DEBUGGING
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00903)
                         "1)IP-Match: %s[%s] <-> ", host, inet_ntoa(addr));
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00904)
                         "%s/", inet_ntoa(This->addr));
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00905)
                         "%s", inet_ntoa(This->mask));
#endif
            return 1;
        }
#if DEBUGGING
        else {
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00906)
                         "1)IP-NoMatch: %s[%s] <-> ", host, inet_ntoa(addr));
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00907)
                         "%s/", inet_ntoa(This->addr));
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00908)
                         "%s", inet_ntoa(This->mask));
        }
#endif
    }
    else {
        struct apr_sockaddr_t *reqaddr;

        if (apr_sockaddr_info_get(&reqaddr, host, APR_UNSPEC, 0, 0, r->pool)
            != APR_SUCCESS) {
#if DEBUGGING
            ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00909)
             "2)IP-NoMatch: hostname=%s msg=Host not found", host);
#endif
            return 0;
        }

        /* Try to deal with multiple IP addr's for a host */
        /* FIXME: This needs to be able to deal with IPv6 */
        while (reqaddr) {
            ip = (struct in_addr *) reqaddr->ipaddr_ptr;
            if (This->addr.s_addr == (ip->s_addr & This->mask.s_addr)) {
#if DEBUGGING
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00910)
                             "3)IP-Match: %s[%s] <-> ", host, inet_ntoa(*ip));
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00911)
                             "%s/", inet_ntoa(This->addr));
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00912)
                             "%s", inet_ntoa(This->mask));
#endif
                return 1;
            }
#if DEBUGGING
            else {
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00913)
                             "3)IP-NoMatch: %s[%s] <-> ", host, inet_ntoa(*ip));
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00914)
                             "%s/", inet_ntoa(This->addr));
                ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(00915)
                             "%s", inet_ntoa(This->mask));
            }
#endif
            reqaddr = reqaddr->next;
        }
    }

    return 0;
}

/* Return TRUE if addr represents a domain name */
PROXY_DECLARE(int) ap_proxy_is_domainname(struct dirconn_entry *This, apr_pool_t *p)
{
    char *addr = This->name;
    int i;

    /* Domain name must start with a '.' */
    if (addr[0] != '.') {
        return 0;
    }

    /* rfc1035 says DNS names must consist of "[-a-zA-Z0-9]" and '.' */
    for (i = 0; apr_isalnum(addr[i]) || addr[i] == '-' || addr[i] == '.'; ++i) {
        continue;
    }

#if 0
    if (addr[i] == ':') {
    ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, APLOGNO(03234)
                     "@@@@ handle optional port in proxy_is_domainname()");
    /* @@@@ handle optional port */
    }
#endif

    if (addr[i] != '\0') {
        return 0;
    }

    /* Strip trailing dots */
    for (i = strlen(addr) - 1; i > 0 && addr[i] == '.'; --i) {
        addr[i] = '\0';
    }

    This->matcher = proxy_match_domainname;
    return 1;
}

/* Return TRUE if host "host" is in domain "domain" */
static int proxy_match_domainname(struct dirconn_entry *This, request_rec *r)
{
    const char *host = proxy_get_host_of_request(r);
    int d_len = strlen(This->name), h_len;

    if (host == NULL) {      /* some error was logged already */
        return 0;
    }

    h_len = strlen(host);

    /* @@@ do this within the setup? */
    /* Ignore trailing dots in domain comparison: */
    while (d_len > 0 && This->name[d_len - 1] == '.') {
        --d_len;
    }
    while (h_len > 0 && host[h_len - 1] == '.') {
        --h_len;
    }
    return h_len > d_len
        && strncasecmp(&host[h_len - d_len], This->name, d_len) == 0;
}

/* Return TRUE if host represents a host name */
PROXY_DECLARE(int) ap_proxy_is_hostname(struct dirconn_entry *This, apr_pool_t *p)
{
    struct apr_sockaddr_t *addr;
    char *host = This->name;
    int i;

    /* Host names must not start with a '.' */
    if (host[0] == '.') {
        return 0;
    }
    /* rfc1035 says DNS names must consist of "[-a-zA-Z0-9]" and '.' */
    for (i = 0; apr_isalnum(host[i]) || host[i] == '-' || host[i] == '.'; ++i);

    if (host[i] != '\0' || apr_sockaddr_info_get(&addr, host, APR_UNSPEC, 0, 0, p) != APR_SUCCESS) {
        return 0;
    }

    This->hostaddr = addr;

    /* Strip trailing dots */
    for (i = strlen(host) - 1; i > 0 && host[i] == '.'; --i) {
        host[i] = '\0';
    }

    This->matcher = proxy_match_hostname;
    return 1;
}

/* Return TRUE if host "host" is equal to host2 "host2" */
static int proxy_match_hostname(struct dirconn_entry *This, request_rec *r)
{
    char *host = This->name;
    const char *host2 = proxy_get_host_of_request(r);
    int h2_len;
    int h1_len;

    if (host == NULL || host2 == NULL) {
        return 0; /* oops! */
    }

    h2_len = strlen(host2);
    h1_len = strlen(host);

#if 0
    struct apr_sockaddr_t *addr = *This->hostaddr;

    /* Try to deal with multiple IP addr's for a host */
    while (addr) {
        if (addr->ipaddr_ptr == ? ? ? ? ? ? ? ? ? ? ? ? ?)
            return 1;
        addr = addr->next;
    }
#endif

    /* Ignore trailing dots in host2 comparison: */
    while (h2_len > 0 && host2[h2_len - 1] == '.') {
        --h2_len;
    }
    while (h1_len > 0 && host[h1_len - 1] == '.') {
        --h1_len;
    }
    return h1_len == h2_len
        && strncasecmp(host, host2, h1_len) == 0;
}

/* Return TRUE if addr is to be matched as a word */
PROXY_DECLARE(int) ap_proxy_is_word(struct dirconn_entry *This, apr_pool_t *p)
{
    This->matcher = proxy_match_word;
    return 1;
}

/* Return TRUE if string "str2" occurs literally in "str1" */
static int proxy_match_word(struct dirconn_entry *This, request_rec *r)
{
    const char *host = proxy_get_host_of_request(r);
    return host != NULL && ap_strstr_c(host, This->name) != NULL;
}

/* Backwards-compatible interface. */
PROXY_DECLARE(int) ap_proxy_checkproxyblock(request_rec *r, proxy_server_conf *conf,
                             apr_sockaddr_t *uri_addr)
{
    return ap_proxy_checkproxyblock2(r, conf, uri_addr->hostname, uri_addr);
}

#define MAX_IP_STR_LEN (46)

PROXY_DECLARE(int) ap_proxy_checkproxyblock2(request_rec *r, proxy_server_conf *conf,
                                             const char *hostname, apr_sockaddr_t *addr)
{
    int j;

    /* XXX FIXME: conf->noproxies->elts is part of an opaque structure */
    for (j = 0; j < conf->noproxies->nelts; j++) {
        struct noproxy_entry *npent = (struct noproxy_entry *) conf->noproxies->elts;
        struct apr_sockaddr_t *conf_addr;

        ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                      "checking remote machine [%s] against [%s]",
                      hostname, npent[j].name);
        if (ap_strstr_c(hostname, npent[j].name) || npent[j].name[0] == '*') {
            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(00916)
                          "connect to remote machine %s blocked: name %s "
                          "matched", hostname, npent[j].name);
            return HTTP_FORBIDDEN;
        }

        /* No IP address checks if no IP address was passed in,
         * i.e. the forward address proxy case, where this server does
         * not resolve the hostname.  */
        if (!addr)
            continue;

        for (conf_addr = npent[j].addr; conf_addr; conf_addr = conf_addr->next) {
            char caddr[MAX_IP_STR_LEN], uaddr[MAX_IP_STR_LEN];
            apr_sockaddr_t *uri_addr;

            if (apr_sockaddr_ip_getbuf(caddr, sizeof caddr, conf_addr))
                continue;

            for (uri_addr = addr; uri_addr; uri_addr = uri_addr->next) {
                if (apr_sockaddr_ip_getbuf(uaddr, sizeof uaddr, uri_addr))
                    continue;
                ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                              "ProxyBlock comparing %s and %s", caddr, uaddr);
                if (!strcmp(caddr, uaddr)) {
                    ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(00917)
                                  "connect to remote machine %s blocked: "
                                  "IP %s matched", hostname, caddr);
                    return HTTP_FORBIDDEN;
                }
            }
        }
    }

    return OK;
}

/* set up the minimal filter set */
PROXY_DECLARE(int) ap_proxy_pre_http_request(conn_rec *c, request_rec *r)
{
    ap_add_input_filter("HTTP_IN", NULL, r, c);
    return OK;
}

PROXY_DECLARE(const char *) ap_proxy_location_reverse_map(request_rec *r,
                              proxy_dir_conf *conf, const char *url)
{
    proxy_req_conf *rconf;
    struct proxy_alias *ent;
    int i, l1, l1_orig, l2;
    char *u;

    /*
     * XXX FIXME: Make sure this handled the ambiguous case of the :<PORT>
     * after the hostname
     * XXX FIXME: Ensure the /uri component is a case sensitive match
     */
    if (r->proxyreq != PROXYREQ_REVERSE) {
        return url;
    }

    l1_orig = strlen(url);
    if (conf->interpolate_env == 1) {
        rconf = ap_get_module_config(r->request_config, &proxy_module);
        ent = (struct proxy_alias *)rconf->raliases->elts;
    }
    else {
        ent = (struct proxy_alias *)conf->raliases->elts;
    }
    for (i = 0; i < conf->raliases->nelts; i++) {
        proxy_server_conf *sconf = (proxy_server_conf *)
            ap_get_module_config(r->server->module_config, &proxy_module);
        proxy_balancer *balancer;
        const char *real = ent[i].real;

        /* Restore the url length, if it had been changed by the code below */
        l1 = l1_orig;

        /*
         * First check if mapping against a balancer and see
         * if we have such a entity. If so, then we need to
         * find the particulars of the actual worker which may
         * or may not be the right one... basically, we need
         * to find which member actually handled this request.
         */
        if (ap_proxy_valid_balancer_name((char *)real, 0) &&
            (balancer = ap_proxy_get_balancer(r->pool, sconf, real, 1))) {
            int n, l3 = 0;
            proxy_worker **worker = (proxy_worker **)balancer->workers->elts;
            const char *urlpart = ap_strchr_c(real + sizeof(BALANCER_PREFIX) - 1, '/');
            if (urlpart) {
                if (!urlpart[1])
                    urlpart = NULL;
                else
                    l3 = strlen(urlpart);
            }
            /* The balancer comparison is a bit trickier.  Given the context
             *   BalancerMember balancer://alias http://example.com/foo
             *   ProxyPassReverse /bash balancer://alias/bar
             * translate url http://example.com/foo/bar/that to /bash/that
             */
            for (n = 0; n < balancer->workers->nelts; n++) {
                l2 = strlen((*worker)->s->name_ex);
                if (urlpart) {
                    /* urlpart (l3) assuredly starts with its own '/' */
                    if ((*worker)->s->name_ex[l2 - 1] == '/')
                        --l2;
                    if (l1 >= l2 + l3
                            && strncasecmp((*worker)->s->name_ex, url, l2) == 0
                            && strncmp(urlpart, url + l2, l3) == 0) {
                        u = apr_pstrcat(r->pool, ent[i].fake, &url[l2 + l3],
                                        NULL);
                        return ap_is_url(u) ? u : ap_construct_url(r->pool, u, r);
                    }
                }
                else if (l1 >= l2 && strncasecmp((*worker)->s->name_ex, url, l2) == 0) {
                    /* edge case where fake is just "/"... avoid double slash */
                    if ((ent[i].fake[0] == '/') && (ent[i].fake[1] == 0) && (url[l2] == '/')) {
                        u = apr_pstrdup(r->pool, &url[l2]);
                    } else {
                        u = apr_pstrcat(r->pool, ent[i].fake, &url[l2], NULL);
                    }
                    return ap_is_url(u) ? u : ap_construct_url(r->pool, u, r);
                }
                worker++;
            }
        }
        else {
            const char *part = url;
            l2 = strlen(real);
            if (real[0] == '/') {
                part = ap_strstr_c(url, "://");
                if (part) {
                    part = ap_strchr_c(part+3, '/');
                    if (part) {
                        l1 = strlen(part);
                    }
                    else {
                        part = url;
                    }
                }
                else {
                    part = url;
                }
            }
            if (l2 > 0 && l1 >= l2 && strncasecmp(real, part, l2) == 0) {
                u = apr_pstrcat(r->pool, ent[i].fake, &part[l2], NULL);
                return ap_is_url(u) ? u : ap_construct_url(r->pool, u, r);
            }
        }
    }

    return url;
}

/*
* Cookies are a bit trickier to match: we've got two substrings to worry
* about, and we can't just find them with strstr 'cos of case.  Regexp
* matching would be an easy fix, but for better consistency with all the
* other matches we'll refrain and use apr_strmatch to find path=/domain=
* and stick to plain strings for the config values.
*/
PROXY_DECLARE(const char *) ap_proxy_cookie_reverse_map(request_rec *r,
                              proxy_dir_conf *conf, const char *str)
{
    proxy_req_conf *rconf = ap_get_module_config(r->request_config,
                                                 &proxy_module);
    struct proxy_alias *ent;
    apr_size_t len = strlen(str);
    const char *newpath = NULL;
    const char *newdomain = NULL;
    const char *pathp;
    const char *domainp;
    const char *pathe = NULL;
    const char *domaine = NULL;
    apr_size_t l1, l2, poffs = 0, doffs = 0;
    int i;
    int ddiff = 0;
    int pdiff = 0;
    char *tmpstr, *tmpstr_orig, *token, *last, *ret;

    if (r->proxyreq != PROXYREQ_REVERSE) {
        return str;
    }

   /*
    * Find the match and replacement, but save replacing until we've done
    * both path and domain so we know the new strlen
    */
    tmpstr_orig = tmpstr = apr_pstrdup(r->pool, str);
    while ((token = apr_strtok(tmpstr, ";", &last))) {
        /* skip leading spaces */
        while (apr_isspace(*token)) {
            ++token;
        }

        if (ap_cstr_casecmpn("path=", token, 5) == 0) {
            pathp = token + 5;
            poffs = pathp - tmpstr_orig;
            l1 = strlen(pathp);
            pathe = str + poffs + l1;
            if (conf->interpolate_env == 1) {
                ent = (struct proxy_alias *)rconf->cookie_paths->elts;
            }
            else {
                ent = (struct proxy_alias *)conf->cookie_paths->elts;
            }
            for (i = 0; i < conf->cookie_paths->nelts; i++) {
                l2 = strlen(ent[i].fake);
                if (l1 >= l2 && strncmp(ent[i].fake, pathp, l2) == 0) {
                    newpath = ent[i].real;
                    pdiff = strlen(newpath) - l1;
                    break;
                }
            }
        }
        else if (ap_cstr_casecmpn("domain=", token, 7) == 0) {
            domainp = token + 7;
            doffs = domainp - tmpstr_orig;
            l1 = strlen(domainp);
            domaine = str + doffs + l1;
            if (conf->interpolate_env == 1) {
                ent = (struct proxy_alias *)rconf->cookie_domains->elts;
            }
            else {
                ent = (struct proxy_alias *)conf->cookie_domains->elts;
            }
            for (i = 0; i < conf->cookie_domains->nelts; i++) {
                l2 = strlen(ent[i].fake);
                if (l1 >= l2 && strncasecmp(ent[i].fake, domainp, l2) == 0) {
                    newdomain = ent[i].real;
                    ddiff = strlen(newdomain) - l1;
                    break;
                }
            }
        }

        /* Iterate the remaining tokens using apr_strtok(NULL, ...) */
        tmpstr = NULL;
    }

    if (newpath) {
        ret = apr_palloc(r->pool, len + pdiff + ddiff + 1);
        l1 = strlen(newpath);
        if (newdomain) {
            l2 = strlen(newdomain);
            if (doffs > poffs) {
                memcpy(ret, str, poffs);
                memcpy(ret + poffs, newpath, l1);
                memcpy(ret + poffs + l1, pathe, str + doffs - pathe);
                memcpy(ret + doffs + pdiff, newdomain, l2);
                strcpy(ret + doffs + pdiff + l2, domaine);
            }
            else {
                memcpy(ret, str, doffs) ;
                memcpy(ret + doffs, newdomain, l2);
                memcpy(ret + doffs + l2, domaine, str + poffs - domaine);
                memcpy(ret + poffs + ddiff, newpath, l1);
                strcpy(ret + poffs + ddiff + l1, pathe);
            }
        }
        else {
            memcpy(ret, str, poffs);
            memcpy(ret + poffs, newpath, l1);
            strcpy(ret + poffs + l1, pathe);
        }
    }
    else if (newdomain) {
            ret = apr_palloc(r->pool, len + ddiff + 1);
            l2 = strlen(newdomain);
            memcpy(ret, str, doffs);
            memcpy(ret + doffs, newdomain, l2);
            strcpy(ret + doffs + l2, domaine);
    }
    else {
        ret = (char *)str; /* no change */
    }

    return ret;
}

/*
* BALANCER related...
*/

/*
* verifies that the balancer name conforms to standards.
*/
PROXY_DECLARE(int) ap_proxy_valid_balancer_name(char *name, int i)
{
    if (!i)
        i = sizeof(BALANCER_PREFIX)-1;
    return (!ap_cstr_casecmpn(name, BALANCER_PREFIX, i));
}

PROXY_DECLARE(proxy_balancer *) ap_proxy_get_balancer(apr_pool_t *p,
                                                      proxy_server_conf *conf,
                                                      const char *url,
                                                      int care)
{
    proxy_balancer *balancer;
    char *c, *uri = apr_pstrdup(p, url);
    int i;
    proxy_hashes hash;

    c = strchr(uri, ':');
    if (c == NULL || c[1] != '/' || c[2] != '/' || c[3] == '\0') {
        return NULL;
    }
    /* remove path from uri */
    if ((c = strchr(c + 3, '/'))) {
        *c = '\0';
    }
    ap_str_tolower(uri);
    hash.def = ap_proxy_hashfunc(uri, PROXY_HASHFUNC_DEFAULT);
    hash.fnv = ap_proxy_hashfunc(uri, PROXY_HASHFUNC_FNV);
    balancer = (proxy_balancer *)conf->balancers->elts;
    for (i = 0; i < conf->balancers->nelts; i++) {
        if (balancer->hash.def == hash.def && balancer->hash.fnv == hash.fnv) {
            if (!care || !balancer->s->inactive) {
                return balancer;
            }
        }
        balancer++;
    }
    return NULL;
}

PROXY_DECLARE(char *) ap_proxy_update_balancer(apr_pool_t *p,
                                                proxy_balancer *balancer,
                                                const char *url)
{
    apr_uri_t puri;
    if (!url) {
        return NULL;
    }
    if (apr_uri_parse(p, url, &puri) != APR_SUCCESS) {
        return apr_psprintf(p, "unable to parse: %s", url);
    }
    if (puri.path && PROXY_STRNCPY(balancer->s->vpath, puri.path) != APR_SUCCESS) {
        return apr_psprintf(p, "balancer %s front-end virtual-path (%s) too long",
                            balancer->s->name, puri.path);
    }
    if (puri.hostname && PROXY_STRNCPY(balancer->s->vhost, puri.hostname) != APR_SUCCESS) {
        return apr_psprintf(p, "balancer %s front-end vhost name (%s) too long",
                            balancer->s->name, puri.hostname);
    }
    return NULL;
}

#define PROXY_UNSET_NONCE '\n'

PROXY_DECLARE(char *) ap_proxy_define_balancer(apr_pool_t *p,
                                               proxy_balancer **balancer,
                                               proxy_server_conf *conf,
                                               const char *url,
                                               const char *alias,
                                               int do_malloc)
{
    proxy_balancer_method *lbmethod;
    proxy_balancer_shared *bshared;
    char *c, *q, *uri = apr_pstrdup(p, url);
    const char *sname;

    /* We should never get here without a valid BALANCER_PREFIX... */

    c = strchr(uri, ':');
    if (c == NULL || c[1] != '/' || c[2] != '/' || c[3] == '\0')
        return apr_psprintf(p, "Bad syntax for a balancer name (%s)", uri);
    /* remove path from uri */
    if ((q = strchr(c + 3, '/')))
        *q = '\0';

    ap_str_tolower(uri);
    *balancer = apr_array_push(conf->balancers);
    memset(*balancer, 0, sizeof(proxy_balancer));

    /*
     * NOTE: The default method is byrequests - if it doesn't
     * exist, that's OK at this time. We check when we share and sync
     */
    lbmethod = ap_lookup_provider(PROXY_LBMETHOD, "byrequests", "0");
    (*balancer)->lbmethod = lbmethod;

    (*balancer)->workers = apr_array_make(p, 5, sizeof(proxy_worker *));
#if APR_HAS_THREADS
    (*balancer)->gmutex = NULL;
    (*balancer)->tmutex = NULL;
#endif

    if (do_malloc)
        bshared = ap_malloc(sizeof(proxy_balancer_shared));
    else
        bshared = apr_palloc(p, sizeof(proxy_balancer_shared));

    memset(bshared, 0, sizeof(proxy_balancer_shared));

    bshared->was_malloced = (do_malloc != 0);
    PROXY_STRNCPY(bshared->lbpname, "byrequests");
    if (PROXY_STRNCPY(bshared->name, uri) != APR_SUCCESS) {
        if (do_malloc) free(bshared);
        return apr_psprintf(p, "balancer name (%s) too long", uri);
    }
    (*balancer)->lbmethod_set = 1;

    /*
     * We do the below for verification. The real sname will be
     * done post_config
     */
    ap_pstr2_alnum(p, bshared->name + sizeof(BALANCER_PREFIX) - 1,
                   &sname);
    sname = apr_pstrcat(p, conf->id, "_", sname, NULL);
    if (PROXY_STRNCPY(bshared->sname, sname) != APR_SUCCESS) {
        if (do_malloc) free(bshared);
        return apr_psprintf(p, "balancer safe-name (%s) too long", sname);
    }
    bshared->hash.def = ap_proxy_hashfunc(bshared->name, PROXY_HASHFUNC_DEFAULT);
    bshared->hash.fnv = ap_proxy_hashfunc(bshared->name, PROXY_HASHFUNC_FNV);
    (*balancer)->hash = bshared->hash;

    bshared->forcerecovery = 1;
    bshared->sticky_separator = '.';
    *bshared->nonce = PROXY_UNSET_NONCE;  /* impossible valid input */

    (*balancer)->s = bshared;
    (*balancer)->sconf = conf;

    return ap_proxy_update_balancer(p, *balancer, alias);
}

/*
* Create an already defined balancer and free up memory.
*/
PROXY_DECLARE(apr_status_t) ap_proxy_share_balancer(proxy_balancer *balancer,
                                                    proxy_balancer_shared *shm,
                                                    int i)
{
    apr_status_t rv = APR_SUCCESS;
    proxy_balancer_method *lbmethod;
    char *action = "copying";
    if (!shm || !balancer->s)
        return APR_EINVAL;

    if ((balancer->s->hash.def != shm->hash.def) ||
        (balancer->s->hash.fnv != shm->hash.fnv)) {
        memcpy(shm, balancer->s, sizeof(proxy_balancer_shared));
        if (balancer->s->was_malloced)
            free(balancer->s);
    } else {
        action = "re-using";
    }
    balancer->s = shm;
    balancer->s->index = i;
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02337)
                 "%s shm[%d] (0x%pp) for %s", action, i, (void *)shm,
                 balancer->s->name);
    /* the below should always succeed */
    lbmethod = ap_lookup_provider(PROXY_LBMETHOD, balancer->s->lbpname, "0");
    if (lbmethod) {
        balancer->lbmethod = lbmethod;
        balancer->lbmethod_set = 1;
    } else {
        ap_log_error(APLOG_MARK, APLOG_CRIT, 0, ap_server_conf, APLOGNO(02432)
                     "Cannot find LB Method: %s", balancer->s->lbpname);
        return APR_EINVAL;
    }
    if (*balancer->s->nonce == PROXY_UNSET_NONCE) {
        char nonce[APR_UUID_FORMATTED_LENGTH + 1];
        apr_uuid_t uuid;

        /* Generate a pseudo-UUID from the PRNG to use as a nonce for
         * the lifetime of the process. uuid.data is a char array so
         * this is an adequate substitute for apr_uuid_get(). */
        ap_random_insecure_bytes(uuid.data, sizeof uuid.data);
        apr_uuid_format(nonce, &uuid);
        rv = PROXY_STRNCPY(balancer->s->nonce, nonce);
    }
    return rv;
}

PROXY_DECLARE(apr_status_t) ap_proxy_initialize_balancer(proxy_balancer *balancer, server_rec *s, apr_pool_t *p)
{
#if APR_HAS_THREADS
    apr_status_t rv = APR_SUCCESS;
#endif
    ap_slotmem_provider_t *storage = balancer->storage;
    apr_size_t size;
    unsigned int num;

    if (!storage) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00918)
                     "no provider for %s", balancer->s->name);
        return APR_EGENERAL;
    }
    /*
     * for each balancer we need to init the global
     * mutex and then attach to the shared worker shm
     */
    if (!balancer->gmutex) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00919)
                     "no mutex %s", balancer->s->name);
        return APR_EGENERAL;
    }

    /* Re-open the mutex for the child. */
    rv = apr_global_mutex_child_init(&(balancer->gmutex),
                                     apr_global_mutex_lockfile(balancer->gmutex),
                                     p);
    if (rv != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s, APLOGNO(00920)
                     "Failed to reopen mutex %s in child",
                     balancer->s->name);
        return rv;
    }

    /* now attach */
    storage->attach(&(balancer->wslot), balancer->s->sname, &size, &num, p);
    if (!balancer->wslot) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00921) "slotmem_attach failed");
        return APR_EGENERAL;
    }

#if APR_HAS_THREADS
    if (balancer->tmutex == NULL) {
        rv = apr_thread_mutex_create(&(balancer->tmutex), APR_THREAD_MUTEX_DEFAULT, p);
        if (rv != APR_SUCCESS) {
            ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, APLOGNO(00922)
                         "can not create balancer thread mutex");
            return rv;
        }
    }
#endif
    return APR_SUCCESS;
}

static proxy_worker *proxy_balancer_get_best_worker(proxy_balancer *balancer,
                                                    request_rec *r,
                                                    proxy_is_best_callback_fn_t *is_best,
                                                    void *baton)
{
    int i = 0;
    int cur_lbset = 0;
    int max_lbset = 0;
    int unusable_workers = 0;
    apr_pool_t *tpool = NULL;
    apr_array_header_t *spares = NULL;
    apr_array_header_t *standbys = NULL;
    proxy_worker *worker = NULL;
    proxy_worker *best_worker = NULL;

    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(10122)
                 "proxy: Entering %s for BALANCER (%s)",
                 balancer->lbmethod->name, balancer->s->name);

    apr_pool_create(&tpool, r->pool);
    apr_pool_tag(tpool, "proxy_lb_best");

    spares = apr_array_make(tpool, 1, sizeof(proxy_worker*));
    standbys = apr_array_make(tpool, 1, sizeof(proxy_worker*));

    /* Process lbsets in order, only replacing unusable workers in a given lbset
     * with available spares from the same lbset. Hot standbys will be used as a
     * last resort when all other workers and spares are unavailable.
     */
    for (cur_lbset = 0; !best_worker && (cur_lbset <= max_lbset); cur_lbset++) {
        unusable_workers = 0;
        apr_array_clear(spares);
        apr_array_clear(standbys);

        for (i = 0; i < balancer->workers->nelts; i++) {
            worker = APR_ARRAY_IDX(balancer->workers, i, proxy_worker *);

            if (worker->s->lbset > max_lbset) {
                max_lbset = worker->s->lbset;
            }

            if (worker->s->lbset != cur_lbset) {
                continue;
            }

            /* A draining worker that is neither a spare nor a standby should be
             * considered unusable to be replaced by spares.
             */
            if (PROXY_WORKER_IS_DRAINING(worker)) {
                if (!PROXY_WORKER_IS_SPARE(worker) && !PROXY_WORKER_IS_STANDBY(worker)) {
                    unusable_workers++;
                }

                continue;
            }

            /* If the worker is in error state run retry on that worker. It will
             * be marked as operational if the retry timeout is elapsed.  The
             * worker might still be unusable, but we try anyway.
             */
            if (!PROXY_WORKER_IS_USABLE(worker)) {
                ap_proxy_retry_worker("BALANCER", worker, r->server);
            }

            if (PROXY_WORKER_IS_SPARE(worker)) {
                if (PROXY_WORKER_IS_USABLE(worker)) {
                    APR_ARRAY_PUSH(spares, proxy_worker *) = worker;
                }
            }
            else if (PROXY_WORKER_IS_STANDBY(worker)) {
                if (PROXY_WORKER_IS_USABLE(worker)) {
                    APR_ARRAY_PUSH(standbys, proxy_worker *) = worker;
                }
            }
            else if (PROXY_WORKER_IS_USABLE(worker)) {
              if (is_best(worker, best_worker, baton)) {
                best_worker = worker;
              }
            }
            else {
                unusable_workers++;
            }
        }

        /* Check if any spares are best. */
        for (i = 0; (i < spares->nelts) && (i < unusable_workers); i++) {
          worker = APR_ARRAY_IDX(spares, i, proxy_worker *);

          if (is_best(worker, best_worker, baton)) {
            best_worker = worker;
          }
        }

        /* If no workers are available, use the standbys. */
        if (!best_worker) {
            for (i = 0; i < standbys->nelts; i++) {
              worker = APR_ARRAY_IDX(standbys, i, proxy_worker *);

              if (is_best(worker, best_worker, baton)) {
                best_worker = worker;
              }
            }
        }
    }

    apr_pool_destroy(tpool);

    if (best_worker) {
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(10123)
                     "proxy: %s selected worker \"%s\" : busy %" APR_SIZE_T_FMT " : lbstatus %d",
                     balancer->lbmethod->name, best_worker->s->name_ex,
                     best_worker->s->busy, best_worker->s->lbstatus);
    }

    return best_worker;
}

PROXY_DECLARE(proxy_worker *) ap_proxy_balancer_get_best_worker(proxy_balancer *balancer,
                                                                request_rec *r,
                                                                proxy_is_best_callback_fn_t *is_best,
                                                                void *baton)
{
    return proxy_balancer_get_best_worker(balancer, r, is_best, baton);
}

/*
* CONNECTION related...
*/

static void socket_cleanup(proxy_conn_rec *conn)
{
    conn->sock = NULL;
    conn->tmp_bb = NULL;
    conn->connection = NULL;
    conn->ssl_hostname = NULL;
    apr_pool_clear(conn->scpool);
    conn->close = 0;
}

static void conn_cleanup(proxy_conn_rec *conn)
{
    socket_cleanup(conn);
    conn->address = NULL;
    conn->addr = NULL;
    conn->hostname = NULL;
    conn->port = 0;
    conn->uds_path = NULL;
    if (conn->uds_pool) {
        apr_pool_clear(conn->uds_pool);
    }
}

static apr_status_t conn_pool_cleanup(void *theworker)
{
    /* Signal that the child is exiting */
    ((proxy_worker *)theworker)->cp = NULL;
    return APR_SUCCESS;
}

static apr_pool_t *make_conn_subpool(apr_pool_t *p, const char *tag,
                                     server_rec *s)
{
    apr_pool_t *sp = NULL;
    apr_allocator_t *alloc;
    apr_thread_mutex_t *mutex;
    apr_status_t rv;

    rv = apr_allocator_create(&alloc);
    if (rv == APR_SUCCESS) {
        rv = apr_thread_mutex_create(&mutex, APR_THREAD_MUTEX_DEFAULT, p);
        if (rv == APR_SUCCESS) {
            apr_allocator_mutex_set(alloc, mutex);
            apr_allocator_max_free_set(alloc, ap_max_mem_free);
            rv = apr_pool_create_ex(&sp, p, NULL, alloc);
        }
        else {
            apr_allocator_destroy(alloc);
        }
    }
    if (rv != APR_SUCCESS) {
        ap_log_error(APLOG_MARK, APLOG_CRIT, rv, s, APLOGNO(10474)
                     "failed to create %s pool", tag);
        ap_abort_on_oom();
        return NULL; /* not reached */
    }
    apr_allocator_owner_set(alloc, sp);
    apr_pool_tag(sp, tag);

    return sp;
}

static void init_conn_pool(apr_pool_t *p, proxy_worker *worker, server_rec *s)
{
    proxy_conn_pool *cp;

    /*
     * Alloc from the same pool as worker.
     * proxy_conn_pool is permanently attached to the worker.
     */
    cp = (proxy_conn_pool *)apr_pcalloc(p, sizeof(proxy_conn_pool));
    worker->cp = cp;

    /*
     * We need a first pool (cp->pool) to maintain the connections attached to
     * the worker and a second one (cp->dns_pool) to maintain the DNS addresses
     * in use (TTL'ed, refcounted). New connections are created as/on a subpool
     * of cp->pool and new addresses as/on a subpool of cp->dns_pool, such that
     * both leaks (the subpools can be destroyed when the connections and/or
     * addresses are over) and race conditions (the creation/destruction of
     * subpools is protected by the parent pool's mutex) can be avoided.
     *
     * cp->dns_pool is created before cp->pool because when a connection on the
     * latter is destroyed it might destroy an address on the former, so when
     * the base pools are destroyed (e.g. child exit) we thusly make sure that
     * cp->dns_pool and its subpools are still alive when cp->pool gets killed.
     *
     * Both cp->dns_pool and cp->pool have their own allocator/mutex too since
     * acquiring connections and addresses don't need to contend.
     */
    cp->dns_pool = make_conn_subpool(p, "proxy_worker_dns", s);
    cp->pool = make_conn_subpool(p, "proxy_worker_cp", s);

    /* When p is cleaning up the child is exiting, signal that to e.g. avoid
     * destroying the subpools explicitely in connection_destructor() when
     * they have been destroyed already by the reslist cleanup.
     */
    apr_pool_pre_cleanup_register(p, worker, conn_pool_cleanup);
}

PROXY_DECLARE(int) ap_proxy_connection_reusable(proxy_conn_rec *conn)
{
    proxy_worker *worker = conn->worker;

    return !(conn->close || worker->s->disablereuse);
}

static proxy_conn_rec *connection_make(apr_pool_t *p, proxy_worker *worker)
{
    proxy_conn_rec *conn;

    conn = apr_pcalloc(p, sizeof(proxy_conn_rec));
    conn->pool = p;
    conn->worker = worker;

    /*
     * Create another subpool that manages the data for the
     * socket and the connection member of the proxy_conn_rec struct as we
     * destroy this data more frequently than other data in the proxy_conn_rec
     * struct like hostname and addr (at least in the case where we have
     * keepalive connections that timed out).
     *
     * XXX: this is really needed only when worker->s->is_address_reusable,
     *      otherwise conn->scpool = conn->pool would be fine. For now we
     *      can't change it since it's (kind of) part of the API.
     */
    apr_pool_create(&conn->scpool, p);
    apr_pool_tag(conn->scpool, "proxy_conn_scpool");

    return conn;
}

static void connection_cleanup(void *theconn)
{
    proxy_conn_rec *conn = (proxy_conn_rec *)theconn;
    proxy_worker *worker = conn->worker;

    /* Sanity check: Did we already return the pooled connection? */
    if (conn->inreslist) {
        ap_log_perror(APLOG_MARK, APLOG_ERR, 0, conn->pool, APLOGNO(00923)
                      "Pooled connection 0x%pp for worker %s has been"
                      " already returned to the connection pool.", conn,
                      ap_proxy_worker_name(conn->pool, worker));
        return;
    }

    if (conn->r) {
        apr_pool_destroy(conn->r->pool);
        conn->r = NULL;
    }

    /* determine if the connection should be cleared, closed or reused */
    if (!worker->s->is_address_reusable) {
        apr_pool_t *p = conn->pool;
        apr_pool_clear(p);
        conn = connection_make(p, worker);
    }
    else if (!conn->sock
             || (conn->connection
                 && conn->connection->keepalive == AP_CONN_CLOSE)
             || !ap_proxy_connection_reusable(conn)) {
        socket_cleanup(conn);
    }
    else if (conn->is_ssl) {
        /* The current ssl section/dir config of the conn is not necessarily
         * the one it will be reused for, so while the conn is in the reslist
         * reset its ssl config to the worker's, until a new user sets its own
         * ssl config eventually in proxy_connection_create() and so on.
         */
        ap_proxy_ssl_engine(conn->connection, worker->section_config, 1);
    }

    if (worker->s->hmax && worker->cp->res) {
        conn->inreslist = 1;
        apr_reslist_release(worker->cp->res, (void *)conn);
    }
    else {
        worker->cp->conn = conn;
    }
}

/* DEPRECATED */
PROXY_DECLARE(apr_status_t) ap_proxy_ssl_connection_cleanup(proxy_conn_rec *conn,
                                                            request_rec *r)
{
    apr_status_t rv;

    /*
     * If we have an existing SSL connection it might be possible that the
     * server sent some SSL message we have not read so far (e.g. an SSL
     * shutdown message if the server closed the keepalive connection while
     * the connection was held unused in our pool).
     * So ensure that if present (=> APR_NONBLOCK_READ) it is read and
     * processed. We don't expect any data to be in the returned brigade.
     */
    if (conn->sock && conn->connection) {
        rv = ap_get_brigade(conn->connection->input_filters, conn->tmp_bb,
                            AP_MODE_READBYTES, APR_NONBLOCK_READ,
                            HUGE_STRING_LEN);
        if (!APR_BRIGADE_EMPTY(conn->tmp_bb)) {
            apr_off_t len;

            rv = apr_brigade_length(conn->tmp_bb, 0, &len);
            ap_log_rerror(APLOG_MARK, APLOG_TRACE3, rv, r,
                          "SSL cleanup brigade contained %"
                          APR_OFF_T_FMT " bytes of data.", len);
            apr_brigade_cleanup(conn->tmp_bb);
        }
        if ((rv != APR_SUCCESS) && !APR_STATUS_IS_EAGAIN(rv)) {
            socket_cleanup(conn);
        }
    }
    return APR_SUCCESS;
}

/* reslist constructor */
static apr_status_t connection_constructor(void **resource, void *params,
                                           apr_pool_t *pool)
{
    apr_pool_t *p;
    proxy_conn_rec *conn;
    proxy_worker *worker = (proxy_worker *)params;

    /*
     * Create a subpool for each connection
     * This keeps the memory consumption constant
     * when it's recycled or destroyed.
     */
    apr_pool_create(&p, pool);
    apr_pool_tag(p, "proxy_conn_pool");
    conn = connection_make(p, worker);
    conn->inreslist = 1;

    *resource = conn;
    return APR_SUCCESS;
}

/* reslist destructor */
static apr_status_t connection_destructor(void *resource, void *params,
                                          apr_pool_t *pool)
{
    proxy_worker *worker = params;

    /* Destroy the pool only if not called from reslist_destroy */
    if (worker->cp) {
        proxy_conn_rec *conn = resource;
        apr_pool_destroy(conn->pool);
    }

    return APR_SUCCESS;
}

/*
* WORKER related...
*/

PROXY_DECLARE(char *) ap_proxy_worker_name(apr_pool_t *p,
                                           proxy_worker *worker)
{
    if (!(*worker->s->uds_path) || !p) {
        /* just in case */
        return worker->s->name_ex;
    }
    return apr_pstrcat(p, "unix:", worker->s->uds_path, "|", worker->s->name_ex, NULL);
}

PROXY_DECLARE(int) ap_proxy_worker_can_upgrade(apr_pool_t *p,
                                               const proxy_worker *worker,
                                               const char *upgrade,
                                               const char *dflt)
{
    /* Find in worker->s->upgrade list (if any) */
    const char *worker_upgrade = worker->s->upgrade;
    if (*worker_upgrade) {
        return (strcmp(worker_upgrade, "*") == 0
                || ap_cstr_casecmp(worker_upgrade, upgrade) == 0
                || ap_find_token(p, worker_upgrade, upgrade));
    }

    /* Compare to the provided default (if any) */
    return (dflt && ap_cstr_casecmp(dflt, upgrade) == 0);
}

/*
* Taken from ap_strcmp_match() :
* Match = 0, NoMatch = 1, Abort = -1, Inval = -2
* Based loosely on sections of wildmat.c by Rich Salz
* Hmmm... shouldn't this really go component by component?
*
* Adds handling of the "\<any>" => "<any>" unescaping.
*/
static int ap_proxy_strcmp_ematch(const char *str, const char *expected)
{
    apr_size_t x, y;

    for (x = 0, y = 0; expected[y]; ++y, ++x) {
        if (expected[y] == '$' && apr_isdigit(expected[y + 1])) {
            do {
                y += 2;
            } while (expected[y] == '$' && apr_isdigit(expected[y + 1]));
            if (!expected[y])
                return 0;
            while (str[x]) {
                int ret;
                if ((ret = ap_proxy_strcmp_ematch(&str[x++], &expected[y])) != 1)
                    return ret;
            }
            return -1;
        }
        else if (!str[x]) {
            return -1;
        }
        else if (expected[y] == '\\' && !expected[++y]) {
            /* NUL is an invalid char! */
            return -2;
        }
        if (str[x] != expected[y])
            return 1;
    }
    /* We got all the way through the worker path without a difference */
    return 0;
}

static int worker_matches(proxy_worker *worker,
                          const char *url, apr_size_t url_len,
                          apr_size_t min_match, apr_size_t *max_match,
                          unsigned int mask)
{
    apr_size_t name_len = strlen(worker->s->name_ex);
    if (name_len <= url_len
        && name_len > *max_match
        /* min_match is the length of the scheme://host part only of url,
         * so it's used as a fast path to avoid the match when url is too
         * small, but it's irrelevant when the worker host contains globs
         * (i.e. ->is_host_matchable).
         */
        && (worker->s->is_name_matchable
            ? ((mask & AP_PROXY_WORKER_IS_MATCH)
               && (worker->s->is_host_matchable || name_len >= min_match)
               && !ap_proxy_strcmp_ematch(url, worker->s->name_ex))
            : ((mask & AP_PROXY_WORKER_IS_PREFIX)
               && (name_len >= min_match)
               && !strncmp(url, worker->s->name_ex, name_len)))) {
        *max_match = name_len;
        return 1;
    }
    return 0;
}

PROXY_DECLARE(proxy_worker *) ap_proxy_get_worker_ex(apr_pool_t *p,
                                                     proxy_balancer *balancer,
                                                     proxy_server_conf *conf,
                                                     const char *url,
                                                     unsigned int mask)
{
    proxy_worker *max_worker = NULL;
    apr_size_t min_match, max_match = 0;
    apr_size_t url_len;
    const char *c;
    char *url_copy;
    int i;

    if (!url) {
        return NULL;
    }

    if (!(mask & AP_PROXY_WORKER_NO_UDS)) {
        url = ap_proxy_de_socketfy(p, url);
        if (!url) {
            return NULL;
        }
    }

    c = ap_strchr_c(url, ':');
    if (c == NULL || c[1] != '/' || c[2] != '/' || c[3] == '\0') {
        return NULL;
    }

    url_len = strlen(url);
    url_copy = apr_pstrmemdup(p, url, url_len);

    /* Default to lookup for both _PREFIX and _MATCH workers */
    if (!(mask & (AP_PROXY_WORKER_IS_PREFIX | AP_PROXY_WORKER_IS_MATCH))) {
        mask |= AP_PROXY_WORKER_IS_PREFIX | AP_PROXY_WORKER_IS_MATCH;
    }

    /*
     * We need to find the start of the path and
     * therefore we know the length of the scheme://hostname/
     * part to we can force-lowercase everything up to
     * the start of the path.
     */
    c = ap_strchr_c(c+3, '/');
    if (c) {
        char *pathstart;
        pathstart = url_copy + (c - url);
        *pathstart = '\0';
        ap_str_tolower(url_copy);
        min_match = strlen(url_copy);
        *pathstart = '/';
    }
    else {
        ap_str_tolower(url_copy);
        min_match = strlen(url_copy);
    }

    /*
     * Do a "longest match" on the worker name to find the worker that
     * fits best to the URL, but keep in mind that we must have at least
     * a minimum matching of length min_match such that
     * scheme://hostname[:port] matches between worker and url.
     */
    if (balancer) {
        proxy_worker **worker = (proxy_worker **)balancer->workers->elts;
        for (i = 0; i < balancer->workers->nelts; i++, worker++) {
            if (worker_matches(*worker, url_copy, url_len,
                               min_match, &max_match, mask)) {
                max_worker = *worker;
            }
        }
    }
    else {
        proxy_worker *worker = (proxy_worker *)conf->workers->elts;
        for (i = 0; i < conf->workers->nelts; i++, worker++) {
            if (worker_matches(worker, url_copy, url_len,
                               min_match, &max_match, mask)) {
                max_worker = worker;
            }
        }
    }

    return max_worker;
}

PROXY_DECLARE(proxy_worker *) ap_proxy_get_worker(apr_pool_t *p,
                                                  proxy_balancer *balancer,
                                                  proxy_server_conf *conf,
                                                  const char *url)
{
    return ap_proxy_get_worker_ex(p, balancer, conf, url, 0);
}

/*
* To create a worker from scratch first we define the
* specifics of the worker; this is all local data.
* We then allocate space for it if data needs to be
* shared. This allows for dynamic addition during
* config and runtime.
*/
PROXY_DECLARE(char *) ap_proxy_define_worker_ex(apr_pool_t *p,
                                             proxy_worker **worker,
                                             proxy_balancer *balancer,
                                             proxy_server_conf *conf,
                                             const char *url,
                                             unsigned int mask)
{
    apr_status_t rv;
    proxy_worker_shared *wshared;
    const char *ptr = NULL, *sockpath = NULL, *pdollars = NULL;
    apr_port_t port_of_scheme;
    int address_not_reusable = 0;
    apr_uri_t uri;

    /*
     * Look to see if we are using UDS:
--> --------------------

--> maximum size reached

--> --------------------

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