http://blog.cafarelli.fr/2013/04/backporting-apache-support-for-websockets-reverse-proxy-aka-getting-gateone-to-work-behind-apache/
https://cafarelli.fr/gentoo/apache-2.2.31-wstunnel.patch
https://bz.apache.org/bugzilla/show_bug.cgi?id=58503

Index: modules/proxy/config.m4
--- modules/proxy/config.m4.orig	2009-09-24 00:20:00.000000000 +0200
+++ modules/proxy/config.m4	2016-04-30 14:54:41.903080391 +0200
@@ -18,6 +18,7 @@
 proxy_http_objs="mod_proxy_http.lo"
 proxy_scgi_objs="mod_proxy_scgi.lo"
 proxy_ajp_objs="mod_proxy_ajp.lo ajp_header.lo ajp_link.lo ajp_msg.lo ajp_utils.lo"
+proxy_wstunnel_objs="mod_proxy_wstunnel.lo"
 proxy_balancer_objs="mod_proxy_balancer.lo"
 
 case "$host" in
@@ -29,6 +30,7 @@
     proxy_http_objs="$proxy_http_objs mod_proxy.la"
     proxy_scgi_objs="$proxy_scgi_objs mod_proxy.la"
     proxy_ajp_objs="$proxy_ajp_objs mod_proxy.la"
+    proxy_wstunnel_objs="$proxy_wstunnel_objs mod_proxy.la"
     proxy_balancer_objs="$proxy_balancer_objs mod_proxy.la"
     ;;
 esac
@@ -37,6 +39,7 @@
 APACHE_MODULE(proxy_ftp, Apache proxy FTP module, $proxy_ftp_objs, , $proxy_mods_enable)
 APACHE_MODULE(proxy_http, Apache proxy HTTP module, $proxy_http_objs, , $proxy_mods_enable)
 APACHE_MODULE(proxy_scgi, Apache proxy SCGI module, $proxy_scgi_objs, , $proxy_mods_enable)
+APACHE_MODULE(proxy_wstunnel, Apache proxy Websocket Tunnel module, $proxy_wstunnel_objs, , $proxy_mods_enable)
 APACHE_MODULE(proxy_ajp, Apache proxy AJP module, $proxy_ajp_objs, , $proxy_mods_enable)
 APACHE_MODULE(proxy_balancer, Apache proxy BALANCER module, $proxy_balancer_objs, , $proxy_mods_enable)
 
Index: modules/proxy/mod_proxy.h
--- modules/proxy/mod_proxy.h.orig	2015-07-15 18:10:27.000000000 +0200
+++ modules/proxy/mod_proxy.h	2016-04-30 14:54:41.903080391 +0200
@@ -792,6 +792,46 @@
                                                 server_rec *server);
 #endif
 
+/**
+ * Create a HTTP request header brigade,  old_cl_val and old_te_val as required.
+ * @parama p              pool
+ * @param header_brigade  header brigade to use/fill
+ * @param r               request
+ * @param p_conn          proxy connection rec
+ * @param worker          selected worker
+ * @param conf            per-server proxy config
+ * @param uri             uri
+ * @param url             url
+ * @param server_portstr  port as string
+ * @param old_cl_val      stored old content-len val
+ * @param old_te_val      stored old TE val
+ * @return                OK or HTTP_EXPECTATION_FAILED
+ */
+PROXY_DECLARE(int) ap_proxy_create_hdrbrgd(apr_pool_t *p,
+                                           apr_bucket_brigade *header_brigade,
+                                           request_rec *r,
+                                           proxy_conn_rec *p_conn,
+                                           proxy_worker *worker,
+                                           proxy_server_conf *conf,
+                                           apr_uri_t *uri,
+                                           char *url, char *server_portstr,
+                                           char **old_cl_val,
+                                           char **old_te_val);
+
+/**
+ * @param bucket_alloc  bucket allocator
+ * @param r             request
+ * @param p_conn        proxy connection
+ * @param origin        connection rec of origin
+ * @param  bb           brigade to send to origin
+ * @param  flush        flush
+ * @return              status (OK)
+ */
+PROXY_DECLARE(int) ap_proxy_pass_brigade(apr_bucket_alloc_t *bucket_alloc,
+                                         request_rec *r, proxy_conn_rec *p_conn,
+                                         conn_rec *origin, apr_bucket_brigade *bb,
+                                         int flush);
+
 #define PROXY_LBMETHOD "proxylbmethod"
 
 /* The number of dynamic workers that can be added when reconfiguring.
Index: modules/proxy/mod_proxy_wstunnel.c
--- modules/proxy/mod_proxy_wstunnel.c.orig	2016-04-30 14:54:41.903080391 +0200
+++ modules/proxy/mod_proxy_wstunnel.c	2016-04-30 14:55:54.131652877 +0200
@@ -0,0 +1,424 @@
+/* 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.
+ */
+
+#include "mod_proxy.h"
+
+module AP_MODULE_DECLARE_DATA proxy_wstunnel_module;
+
+/*
+ * Canonicalise http-like URLs.
+ * scheme is the scheme for the URL
+ * url is the URL starting with the first '/'
+ * def_port is the default port for this scheme.
+ */
+static int proxy_wstunnel_canon(request_rec *r, char *url)
+{
+    char *host, *path, sport[7];
+    char *search = NULL;
+    const char *err;
+    char *scheme;
+    apr_port_t port, def_port;
+
+    /* ap_port_of_scheme() */
+    if (strncasecmp(url, "ws:", 3) == 0) {
+        url += 3;
+        scheme = "ws:";
+        def_port = apr_uri_port_of_scheme("http");
+    }
+    else if (strncasecmp(url, "wss:", 4) == 0) {
+        url += 4;
+        scheme = "wss:";
+        def_port = apr_uri_port_of_scheme("https");
+    }
+    else {
+        return DECLINED;
+    }
+
+    port = def_port;
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "canonicalising URL %s", url);
+
+    /*
+     * do syntactic check.
+     * We break the URL into host, port, path, search
+     */
+    err = ap_proxy_canon_netloc(r->pool, &url, NULL, NULL, &host, &port);
+    if (err) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, "AH02439: " "error parsing URL %s: %s",
+                      url, err);
+        return HTTP_BAD_REQUEST;
+    }
+
+    /*
+     * now parse path/search args, according to rfc1738:
+     * process the path. With proxy-nocanon set (by
+     * mod_proxy) we use the raw, unparsed uri
+     */
+    if (apr_table_get(r->notes, "proxy-nocanon")) {
+        path = url;   /* this is the raw path */
+    }
+    else {
+        path = ap_proxy_canonenc(r->pool, url, strlen(url), enc_path, 0,
+                                 r->proxyreq);
+        search = r->args;
+    }
+    if (path == NULL)
+        return HTTP_BAD_REQUEST;
+
+    apr_snprintf(sport, sizeof(sport), ":%d", port);
+
+    if (ap_strchr_c(host, ':')) {
+        /* if literal IPv6 address */
+        host = apr_pstrcat(r->pool, "[", host, "]", NULL);
+    }
+    r->filename = apr_pstrcat(r->pool, "proxy:", scheme, "//", host, sport,
+                              "/", path, (search) ? "?" : "",
+                              (search) ? search : "", NULL);
+    return OK;
+}
+
+
+static int proxy_wstunnel_transfer(request_rec *r, conn_rec *c_i, conn_rec *c_o,
+                                     apr_bucket_brigade *bb, char *name)
+{
+    int rv;
+#ifdef DEBUGGING
+    apr_off_t len;
+#endif
+
+    do {
+        apr_brigade_cleanup(bb);
+        rv = ap_get_brigade(c_i->input_filters, bb, AP_MODE_READBYTES,
+                            APR_NONBLOCK_READ, AP_IOBUFSIZE);
+        if (rv == APR_SUCCESS) {
+            if (c_o->aborted) {
+                rv = APR_EPIPE;
+                break;
+            }
+            if (APR_BRIGADE_EMPTY(bb)) {
+                break;
+            }
+#ifdef DEBUGGING
+            len = -1;
+            apr_brigade_length(bb, 0, &len);
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "AH02440: "
+                          "read %" APR_OFF_T_FMT
+                          " bytes from %s", len, name);
+#endif
+            rv = ap_pass_brigade(c_o->output_filters, bb);
+            if (rv == APR_SUCCESS) {
+                apr_brigade_cleanup(bb);
+                ap_fflush(c_o->output_filters, bb);
+            }
+            else {
+                ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, "AH02441: "
+                              "error on %s - ap_pass_brigade",
+                              name);
+            }
+        } else if (!APR_STATUS_IS_EAGAIN(rv) && !APR_STATUS_IS_EOF(rv)) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, r, "AH02442: "
+                          "error on %s - ap_get_brigade",
+                          name);
+        }
+    } while (rv == APR_SUCCESS);
+    apr_brigade_cleanup(bb);
+
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, rv, r, "wstunnel_transfer complete");
+
+    if (APR_STATUS_IS_EAGAIN(rv)) {
+        rv = APR_SUCCESS;
+    }
+   
+    return rv;
+}
+
+/* Search thru the input filters and remove the reqtimeout one */
+static void remove_reqtimeout(ap_filter_t *next)
+{
+    ap_filter_t *reqto = NULL;
+    ap_filter_rec_t *filter;
+
+    filter = ap_get_input_filter_handle("reqtimeout");
+    if (!filter) {
+        return;
+    }
+
+    while (next) {
+        if (next->frec == filter) {
+            reqto = next;
+            break;
+        }
+        next = next->next;
+    }
+    if (reqto) {
+        ap_remove_input_filter(reqto);
+    }
+}
+
+/*
+ * process the request and write the response.
+ */
+static int ap_proxy_wstunnel_request(apr_pool_t *p, request_rec *r,
+                                proxy_conn_rec *conn,
+                                proxy_worker *worker,
+                                proxy_server_conf *conf,
+                                apr_uri_t *uri,
+                                char *url, char *server_portstr)
+{
+    apr_status_t rv = APR_SUCCESS;
+    apr_pollset_t *pollset;
+    apr_pollfd_t pollfd;
+    const apr_pollfd_t *signalled;
+    apr_int32_t pollcnt, pi;
+    apr_int16_t pollevent;
+    conn_rec *c = r->connection;
+    apr_socket_t *sock = conn->sock;
+    conn_rec *backconn = conn->connection;
+    char *buf;
+    apr_bucket_brigade *header_brigade;
+    apr_bucket *e;
+    char *old_cl_val = NULL;
+    char *old_te_val = NULL;
+    apr_bucket_brigade *bb = apr_brigade_create(p, c->bucket_alloc);
+    apr_socket_t *client_socket = ap_get_module_config(c->conn_config, &core_module);
+
+    header_brigade = apr_brigade_create(p, backconn->bucket_alloc);
+
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "sending request");
+
+    rv = ap_proxy_create_hdrbrgd(p, header_brigade, r, conn,
+                                 worker, conf, uri, url, server_portstr,
+                                 &old_cl_val, &old_te_val);
+    if (rv != OK) {
+        return rv;
+    }
+
+    buf = apr_pstrcat(p, "Upgrade: WebSocket", CRLF, "Connection: Upgrade", CRLF, CRLF, NULL);
+    ap_xlate_proto_to_ascii(buf, strlen(buf));
+    e = apr_bucket_pool_create(buf, strlen(buf), p, c->bucket_alloc);
+    APR_BRIGADE_INSERT_TAIL(header_brigade, e);
+
+    if ((rv = ap_proxy_pass_brigade(c->bucket_alloc, r, conn, backconn,
+                                    header_brigade, 1)) != OK)
+        return rv;
+
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "setting up poll()");
+
+    if ((rv = apr_pollset_create(&pollset, 2, p, 0)) != APR_SUCCESS) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, "AH02443: "
+                      "error apr_pollset_create()");
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+#if 0
+    apr_socket_opt_set(sock, APR_SO_NONBLOCK, 1);
+    apr_socket_opt_set(sock, APR_SO_KEEPALIVE, 1);
+    apr_socket_opt_set(client_socket, APR_SO_NONBLOCK, 1);
+    apr_socket_opt_set(client_socket, APR_SO_KEEPALIVE, 1);
+#endif
+
+    pollfd.p = p;
+    pollfd.desc_type = APR_POLL_SOCKET;
+    pollfd.reqevents = APR_POLLIN | APR_POLLHUP;
+    pollfd.desc.s = sock;
+    pollfd.client_data = NULL;
+    apr_pollset_add(pollset, &pollfd);
+
+    pollfd.desc.s = client_socket;
+    apr_pollset_add(pollset, &pollfd);
+
+    remove_reqtimeout(c->input_filters);
+
+    r->output_filters = c->output_filters;
+    r->proto_output_filters = c->output_filters;
+    r->input_filters = c->input_filters;
+    r->proto_input_filters = c->input_filters;
+
+    /* This handler should take care of the entire connection; make it so that
+     * nothing else is attempted on the connection after returning. */
+    c->keepalive = AP_CONN_CLOSE;
+
+    while (1) { /* Infinite loop until error (one side closes the connection) */
+        if ((rv = apr_pollset_poll(pollset, -1, &pollcnt, &signalled))
+            != APR_SUCCESS) {
+            if (APR_STATUS_IS_EINTR(rv)) {
+                continue;
+            }
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, "AH02444: " "error apr_poll()");
+            return HTTP_INTERNAL_SERVER_ERROR;
+        }
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "AH02445: "
+                      "woke from poll(), i=%d", pollcnt);
+
+        for (pi = 0; pi < pollcnt; pi++) {
+            const apr_pollfd_t *cur = &signalled[pi];
+
+            if (cur->desc.s == sock) {
+                pollevent = cur->rtnevents;
+                if (pollevent & (APR_POLLIN | APR_POLLHUP)) {
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "AH02446: "
+                                  "sock was readable");
+                    rv = proxy_wstunnel_transfer(r, backconn, c, bb, "sock");
+                }
+                else if (pollevent & APR_POLLERR) {
+                    rv = APR_EPIPE;
+                    ap_log_rerror(APLOG_MARK, APLOG_NOTICE, 0, r, "AH02447: "
+                       "err/hup on backconn");
+                }
+                else { 
+                    rv = APR_EGENERAL;
+                    ap_log_rerror(APLOG_MARK, APLOG_NOTICE, 0, r, "AH02605: "
+                            "unknown event on backconn %d", pollevent);
+                }
+            }
+            else if (cur->desc.s == client_socket) {
+                pollevent = cur->rtnevents;
+                if (pollevent & (APR_POLLIN | APR_POLLHUP)) {
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "AH02448: "
+                                  "client was readable");
+                    rv = proxy_wstunnel_transfer(r, c, backconn, bb, "client");
+                }
+                else if (pollevent & APR_POLLERR) {
+                    rv = APR_EPIPE;
+                    c->aborted = 1;
+                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "AH02607: "
+                            "error on client conn");
+                }
+                else { 
+                    rv = APR_EGENERAL;
+                    ap_log_rerror(APLOG_MARK, APLOG_NOTICE, 0, r, "AH02606: "
+                            "unknown event on client conn %d", pollevent);
+                }
+            }
+            else {
+                rv = APR_EBADF;
+                ap_log_rerror(APLOG_MARK, APLOG_INFO, 0, r, "AH02449: "
+                              "unknown socket in pollset");
+            }
+
+        }
+        if (rv != APR_SUCCESS) {
+            break;
+        }
+    }
+
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                  "finished with poll() - cleaning up");
+
+    return OK;
+}
+
+/*
+ */
+static int proxy_wstunnel_handler(request_rec *r, proxy_worker *worker,
+                             proxy_server_conf *conf,
+                             char *url, const char *proxyname,
+                             apr_port_t proxyport)
+{
+    int status;
+    char server_portstr[32];
+    proxy_conn_rec *backend = NULL;
+    char *scheme;
+    int retry;
+    conn_rec *c = r->connection;
+    apr_pool_t *p = r->pool;
+    apr_uri_t *uri;
+    int is_ssl = 0;
+
+    if (strncasecmp(url, "wss:", 4) == 0) {
+        scheme = "WSS";
+        is_ssl = 1;
+    }
+    else if (strncasecmp(url, "ws:", 3) == 0) {
+        scheme = "WS";
+    }
+    else {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "AH02450: " "declining URL %s", url);
+        return DECLINED;
+    }
+
+    uri = apr_palloc(p, sizeof(*uri));
+    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, "AH02451: " "serving URL %s", url);
+
+    /* create space for state information */
+    status = ap_proxy_acquire_connection(scheme, &backend, worker,
+                                         r->server);
+    if (status != OK) {
+        if (backend) {
+            backend->close = 1;
+            ap_proxy_release_connection(scheme, backend, r->server);
+        }
+        return status;
+    }
+
+    backend->is_ssl = is_ssl;
+    backend->close = 0;
+
+    retry = 0;
+    while (retry < 2) {
+        char *locurl = url;
+        /* Step One: Determine Who To Connect To */
+        status = ap_proxy_determine_connection(p, r, conf, worker, backend,
+                                               uri, &locurl, proxyname, proxyport,
+                                               server_portstr,
+                                               sizeof(server_portstr));
+
+        if (status != OK)
+            break;
+
+        /* Step Two: Make the Connection */
+        if (ap_proxy_connect_backend(scheme, backend, worker, r->server)) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, "AH02452: "
+                          "failed to make connection to backend: %s",
+                          backend->hostname);
+            status = HTTP_SERVICE_UNAVAILABLE;
+            break;
+        }
+        /* Step Three: Create conn_rec */
+        if (!backend->connection) {
+            if ((status = ap_proxy_connection_create(scheme, backend,
+                                                     c, r->server)) != OK)
+                break;
+        }
+
+        backend->close = 1; /* must be after ap_proxy_determine_connection */
+
+
+        /* Step Three: Process the Request */
+        status = ap_proxy_wstunnel_request(p, r, backend, worker, conf, uri, locurl,
+                                      server_portstr);
+        break;
+    }
+
+    /* Do not close the socket */
+    ap_proxy_release_connection(scheme, backend, r->server);
+    return status;
+}
+
+static void ap_proxy_http_register_hook(apr_pool_t *p)
+{
+    proxy_hook_scheme_handler(proxy_wstunnel_handler, NULL, NULL, APR_HOOK_FIRST);
+    proxy_hook_canon_handler(proxy_wstunnel_canon, NULL, NULL, APR_HOOK_FIRST);
+}
+
+module AP_MODULE_DECLARE_DATA proxy_wstunnel_module = {
+    STANDARD20_MODULE_STUFF,
+    NULL,                       /* create per-directory config structure */
+    NULL,                       /* merge per-directory config structures */
+    NULL,                       /* create per-server config structure */
+    NULL,                       /* merge per-server config structures */
+    NULL,                       /* command apr_table_t */
+    ap_proxy_http_register_hook /* register hooks */
+};
Index: modules/proxy/proxy_util.c
--- modules/proxy/proxy_util.c.orig	2015-07-15 18:10:27.000000000 +0200
+++ modules/proxy/proxy_util.c	2016-04-30 14:54:41.903080391 +0200
@@ -2797,3 +2797,329 @@
     }
     return rv;
 }
+
+/* Clear all connection-based headers from the incoming headers table */
+typedef struct header_dptr {
+    apr_pool_t *pool;
+    apr_table_t *table;
+    apr_time_t time;
+} header_dptr;
+
+static int clear_conn_headers(void *data, const char *key, const char *val)
+{
+    apr_table_t *headers = ((header_dptr*)data)->table;
+    apr_pool_t *pool = ((header_dptr*)data)->pool;
+    const char *name;
+    char *next = apr_pstrdup(pool, val);
+    while (*next) {
+        name = next;
+        while (*next && !apr_isspace(*next) && (*next != ',')) {
+            ++next;
+        }
+        while (*next && (apr_isspace(*next) || (*next == ','))) {
+            *next++ = '\0';
+        }
+        apr_table_unset(headers, name);
+    }
+    return 1;
+}
+
+static void proxy_clear_connection(apr_pool_t *p, apr_table_t *headers)
+{
+    header_dptr x;
+    x.pool = p;
+    x.table = headers;
+    apr_table_unset(headers, "Proxy-Connection");
+    apr_table_do(clear_conn_headers, &x, headers, "Connection", NULL);
+    apr_table_unset(headers, "Connection");
+}
+
+PROXY_DECLARE(int) ap_proxy_create_hdrbrgd(apr_pool_t *p,
+                                            apr_bucket_brigade *header_brigade,
+                                            request_rec *r,
+                                            proxy_conn_rec *p_conn,
+                                            proxy_worker *worker,
+                                            proxy_server_conf *conf,
+                                            apr_uri_t *uri,
+                                            char *url, char *server_portstr,
+                                            char **old_cl_val,
+                                            char **old_te_val)
+{
+    conn_rec *c = r->connection;
+    int counter;
+    char *buf;
+    const apr_array_header_t *headers_in_array;
+    const apr_table_entry_t *headers_in;
+    apr_table_t *headers_in_copy;
+    apr_bucket *e;
+    int do_100_continue;
+    conn_rec *origin = p_conn->connection;
+    proxy_dir_conf *dconf = ap_get_module_config(r->per_dir_config, &proxy_module);
+
+    /*
+     * To be compliant, we only use 100-Continue for requests with bodies.
+     * We also make sure we won't be talking HTTP/1.0 as well.
+     */
+    do_100_continue = (worker->ping_timeout_set
+                       && !r->header_only
+                       && (apr_table_get(r->headers_in, "Content-Length")
+                          || apr_table_get(r->headers_in, "Transfer-Encoding"))
+                       && (PROXYREQ_REVERSE == r->proxyreq)
+                       && !(apr_table_get(r->subprocess_env, "force-proxy-request-1.0")));
+
+    if (apr_table_get(r->subprocess_env, "force-proxy-request-1.0")) {
+        /*
+         * According to RFC 2616 8.2.3 we are not allowed to forward an
+         * Expect: 100-continue to an HTTP/1.0 server. Instead we MUST return
+         * a HTTP_EXPECTATION_FAILED
+         */
+        if (r->expecting_100) {
+            return HTTP_EXPECTATION_FAILED;
+        }
+        buf = apr_pstrcat(p, r->method, " ", url, " HTTP/1.0" CRLF, NULL);
+        p_conn->close = 1;
+    } else {
+        buf = apr_pstrcat(p, r->method, " ", url, " HTTP/1.1" CRLF, NULL);
+    }
+    if (apr_table_get(r->subprocess_env, "proxy-nokeepalive")) {
+        origin->keepalive = AP_CONN_CLOSE;
+        p_conn->close = 1;
+    }
+    ap_xlate_proto_to_ascii(buf, strlen(buf));
+    e = apr_bucket_pool_create(buf, strlen(buf), p, c->bucket_alloc);
+    APR_BRIGADE_INSERT_TAIL(header_brigade, e);
+    if (conf->preserve_host == 0) {
+        if (ap_strchr_c(uri->hostname, ':')) { /* if literal IPv6 address */
+            if (uri->port_str && uri->port != DEFAULT_HTTP_PORT) {
+                buf = apr_pstrcat(p, "Host: [", uri->hostname, "]:",
+                                  uri->port_str, CRLF, NULL);
+            } else {
+                buf = apr_pstrcat(p, "Host: [", uri->hostname, "]", CRLF, NULL);
+            }
+        } else {
+            if (uri->port_str && uri->port != DEFAULT_HTTP_PORT) {
+                buf = apr_pstrcat(p, "Host: ", uri->hostname, ":",
+                                  uri->port_str, CRLF, NULL);
+            } else {
+                buf = apr_pstrcat(p, "Host: ", uri->hostname, CRLF, NULL);
+            }
+        }
+    }
+    else {
+        /* don't want to use r->hostname, as the incoming header might have a
+         * port attached
+         */
+        const char* hostname = apr_table_get(r->headers_in,"Host");
+        if (!hostname) {
+            hostname =  r->server->server_hostname;
+            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, "AH01092: "
+                          "no HTTP 0.9 request (with no host line) "
+                          "on incoming request and preserve host set "
+                          "forcing hostname to be %s for uri %s",
+                          hostname, r->uri);
+        }
+        buf = apr_pstrcat(p, "Host: ", hostname, CRLF, NULL);
+    }
+    ap_xlate_proto_to_ascii(buf, strlen(buf));
+    e = apr_bucket_pool_create(buf, strlen(buf), p, c->bucket_alloc);
+    APR_BRIGADE_INSERT_TAIL(header_brigade, e);
+
+    /* handle Via */
+    if (conf->viaopt == via_block) {
+        /* Block all outgoing Via: headers */
+        apr_table_unset(r->headers_in, "Via");
+    } else if (conf->viaopt != via_off) {
+        const char *server_name = ap_get_server_name(r);
+        /* If USE_CANONICAL_NAME_OFF was configured for the proxy virtual host,
+         * then the server name returned by ap_get_server_name() is the
+         * origin server name (which does make too much sense with Via: headers)
+         * so we use the proxy vhost's name instead.
+         */
+        if (server_name == r->hostname)
+            server_name = r->server->server_hostname;
+        /* Create a "Via:" request header entry and merge it */
+        /* Generate outgoing Via: header with/without server comment: */
+        apr_table_mergen(r->headers_in, "Via",
+                         (conf->viaopt == via_full)
+                         ? apr_psprintf(p, "%d.%d %s%s (%s)",
+                                        HTTP_VERSION_MAJOR(r->proto_num),
+                                        HTTP_VERSION_MINOR(r->proto_num),
+                                        server_name, server_portstr,
+                                        AP_SERVER_BASEVERSION)
+                         : apr_psprintf(p, "%d.%d %s%s",
+                                        HTTP_VERSION_MAJOR(r->proto_num),
+                                        HTTP_VERSION_MINOR(r->proto_num),
+                                        server_name, server_portstr)
+                         );
+    }
+
+    /* Use HTTP/1.1 100-Continue as quick "HTTP ping" test
+     * to backend
+     */
+    if (do_100_continue) {
+        apr_table_mergen(r->headers_in, "Expect", "100-Continue");
+        r->expecting_100 = 1;
+    }
+
+    /* X-Forwarded-*: handling
+     *
+     * XXX Privacy Note:
+     * -----------------
+     *
+     * These request headers are only really useful when the mod_proxy
+     * is used in a reverse proxy configuration, so that useful info
+     * about the client can be passed through the reverse proxy and on
+     * to the backend server, which may require the information to
+     * function properly.
+     *
+     * In a forward proxy situation, these options are a potential
+     * privacy violation, as information about clients behind the proxy
+     * are revealed to arbitrary servers out there on the internet.
+     *
+     * The HTTP/1.1 Via: header is designed for passing client
+     * information through proxies to a server, and should be used in
+     * a forward proxy configuation instead of X-Forwarded-*. See the
+     * ProxyVia option for details.
+     */
+    if (PROXYREQ_REVERSE == r->proxyreq) {
+        const char *buf;
+
+        /* Add X-Forwarded-For: so that the upstream has a chance to
+         * determine, where the original request came from.
+         */
+        apr_table_mergen(r->headers_in, "X-Forwarded-For",
+                         c->remote_ip);
+
+        /* Add X-Forwarded-Host: so that upstream knows what the
+         * original request hostname was.
+         */
+        if ((buf = apr_table_get(r->headers_in, "Host"))) {
+            apr_table_mergen(r->headers_in, "X-Forwarded-Host", buf);
+        }
+
+        /* Add X-Forwarded-Server: so that upstream knows what the
+         * name of this proxy server is (if there are more than one)
+         * XXX: This duplicates Via: - do we strictly need it?
+         */
+        apr_table_mergen(r->headers_in, "X-Forwarded-Server",
+                         r->server->server_hostname);
+    }
+
+    proxy_run_fixups(r);
+    /*
+     * Make a copy of the headers_in table before clearing the connection
+     * headers as we need the connection headers later in the http output
+     * filter to prepare the correct response headers.
+     *
+     * Note: We need to take r->pool for apr_table_copy as the key / value
+     * pairs in r->headers_in have been created out of r->pool and
+     * p might be (and actually is) a longer living pool.
+     * This would trigger the bad pool ancestry abort in apr_table_copy if
+     * apr is compiled with APR_POOL_DEBUG.
+     */
+    headers_in_copy = apr_table_copy(r->pool, r->headers_in);
+    proxy_clear_connection(p, headers_in_copy);
+    /* send request headers */
+    headers_in_array = apr_table_elts(headers_in_copy);
+    headers_in = (const apr_table_entry_t *) headers_in_array->elts;
+    for (counter = 0; counter < headers_in_array->nelts; counter++) {
+        if (headers_in[counter].key == NULL
+            || headers_in[counter].val == NULL
+
+            /* Already sent */
+            || !strcasecmp(headers_in[counter].key, "Host")
+
+            /* Clear out hop-by-hop request headers not to send
+             * RFC2616 13.5.1 says we should strip these headers
+             */
+            || !strcasecmp(headers_in[counter].key, "Keep-Alive")
+            || !strcasecmp(headers_in[counter].key, "TE")
+            || !strcasecmp(headers_in[counter].key, "Trailer")
+            || !strcasecmp(headers_in[counter].key, "Upgrade")
+
+            ) {
+            continue;
+        }
+        /* Do we want to strip Proxy-Authorization ?
+         * If we haven't used it, then NO
+         * If we have used it then MAYBE: RFC2616 says we MAY propagate it.
+         * So let's make it configurable by env.
+         */
+        if (!strcasecmp(headers_in[counter].key,"Proxy-Authorization")) {
+            if (r->user != NULL) { /* we've authenticated */
+                if (!apr_table_get(r->subprocess_env, "Proxy-Chain-Auth")) {
+                    continue;
+                }
+            }
+        }
+
+        /* Skip Transfer-Encoding and Content-Length for now.
+         */
+        if (!strcasecmp(headers_in[counter].key, "Transfer-Encoding")) {
+            *old_te_val = headers_in[counter].val;
+            continue;
+        }
+        if (!strcasecmp(headers_in[counter].key, "Content-Length")) {
+            *old_cl_val = headers_in[counter].val;
+            continue;
+        }
+
+        /* for sub-requests, ignore freshness/expiry headers */
+        if (r->main) {
+            if (    !strcasecmp(headers_in[counter].key, "If-Match")
+                || !strcasecmp(headers_in[counter].key, "If-Modified-Since")
+                || !strcasecmp(headers_in[counter].key, "If-Range")
+                || !strcasecmp(headers_in[counter].key, "If-Unmodified-Since")
+                || !strcasecmp(headers_in[counter].key, "If-None-Match")) {
+                continue;
+            }
+        }
+
+        buf = apr_pstrcat(p, headers_in[counter].key, ": ",
+                          headers_in[counter].val, CRLF,
+                          NULL);
+        ap_xlate_proto_to_ascii(buf, strlen(buf));
+        e = apr_bucket_pool_create(buf, strlen(buf), p, c->bucket_alloc);
+        APR_BRIGADE_INSERT_TAIL(header_brigade, e);
+    }
+    return OK;
+}
+
+PROXY_DECLARE(int) ap_proxy_pass_brigade(apr_bucket_alloc_t *bucket_alloc,
+                                         request_rec *r, proxy_conn_rec *p_conn,
+                                         conn_rec *origin, apr_bucket_brigade *bb,
+                                         int flush)
+{
+    apr_status_t status;
+    apr_off_t transferred;
+
+    if (flush) {
+        apr_bucket *e = apr_bucket_flush_create(bucket_alloc);
+        APR_BRIGADE_INSERT_TAIL(bb, e);
+    }
+    apr_brigade_length(bb, 0, &transferred);
+    if (transferred != -1)
+        p_conn->worker->s->transferred += transferred;
+    status = ap_pass_brigade(origin->output_filters, bb);
+    if (status != APR_SUCCESS) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, status, r->server,
+                     "proxy: pass request body failed to %pI (%s)",
+                      p_conn->addr, p_conn->hostname);
+        if (origin->aborted) {
+            const char *ssl_note;
+
+            if (((ssl_note = apr_table_get(origin->notes, "SSL_connect_rv"))
+                 != NULL) && (strcmp(ssl_note, "err") == 0)) {
+                return ap_proxyerror(r, HTTP_INTERNAL_SERVER_ERROR,
+                                     "Error during SSL Handshake with"
+                                     " remote server");
+            }
+            return APR_STATUS_IS_TIMEUP(status) ? HTTP_GATEWAY_TIME_OUT : HTTP_BAD_GATEWAY;
+        }
+        else {
+            return HTTP_BAD_REQUEST;
+        }
+    }
+    apr_brigade_cleanup(bb);
+    return OK;
+}
