mod_proxy_http.c

        if (!strcasecmp(date_hdrs[i], key)) {
            apr_table_add(r->headers_out, key,
                          date_canon(r->pool, value));
            return;
        }
    }
    for (i = 0; transform_hdrs[i].name; ++i) {
        if (!strcasecmp(transform_hdrs[i].name, key)) {
            apr_table_add(r->headers_out, key,
                          (*transform_hdrs[i].func)(r, c, value));
            return;
       }
    }
    apr_table_add(r->headers_out, key, value);
}

/*
 * Note: pread_len is the length of the response that we've  mistakenly
 * read (assuming that we don't consider that an  error via
 * ProxyBadHeader StartBody). This depends on buffer actually being
 * local storage to the calling code in order for pread_len to make
 * any sense at all, since we depend on buffer still containing
 * what was read by ap_getline() upon return.
 */
static void ap_proxy_read_headers(request_rec *r, request_rec *rr,
                                  char *buffer, int size,
                                  conn_rec *c, int *pread_len)
{
    int len;
    char *value, *end;
    char field[MAX_STRING_LEN];
    int saw_headers = 0;
    void *sconf = r->server->module_config;
    proxy_server_conf *psc;
    proxy_dir_conf *dconf;

    dconf = ap_get_module_config(r->per_dir_config, &proxy_module);
    psc = (proxy_server_conf *) ap_get_module_config(sconf, &proxy_module);

    r->headers_out = apr_table_make(r->pool, 20);
    r->trailers_out = apr_table_make(r->pool, 5);
    *pread_len = 0;

    /*
     * Read header lines until we get the empty separator line, a read error,
     * the connection closes (EOF), or we timeout.
     */
    ap_log_rerror(APLOG_MARK, APLOG_TRACE4, 0, r,
                  "Headers received from backend:");
    while ((len = ap_getline(buffer, size, rr, 1)) > 0) {
        ap_log_rerror(APLOG_MARK, APLOG_TRACE4, 0, r, "%s", buffer);

        if (!(value = strchr(buffer, ':'))) {     /* Find the colon separator */

            /* We may encounter invalid headers, usually from buggy
             * MS IIS servers, so we need to determine just how to handle
             * them. We can either ignore them, assume that they mark the
             * start-of-body (eg: a missing CRLF) or (the default) mark
             * the headers as totally bogus and return a 500. The sole
             * exception is an extra "HTTP/1.0 200, OK" line sprinkled
             * in between the usual MIME headers, which is a favorite
             * IIS bug.
             */
             /* XXX: The mask check is buggy if we ever see an HTTP/1.10 */

            if (!apr_date_checkmask(buffer, "HTTP/#.# ###*")) {
                if (psc->badopt == bad_error) {
                    /* Nope, it wasn't even an extra HTTP header. Give up. */
                    r->headers_out = NULL;
                    return;
                }
                else if (psc->badopt == bad_body) {
                    /* if we've already started loading headers_out, then
                     * return what we've accumulated so far, in the hopes
                     * that they are useful; also note that we likely pre-read
                     * the first line of the response.
                     */
                    if (saw_headers) {
                        ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(01098)
                                      "Starting body due to bogus non-header "
                                      "in headers returned by %s (%s)",
                                      r->uri, r->method);
                        *pread_len = len;
                        return;
                    }
                    else {
                        ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(01099)
                                      "No HTTP headers returned by %s (%s)",
                                      r->uri, r->method);
                        return;
                    }
                }
            }
            /* this is the psc->badopt == bad_ignore case */
            ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(01100)
                          "Ignoring bogus HTTP header returned by %s (%s)",
                          r->uri, r->method);
            continue;
        }

        *value = '\0';
        ++value;
        /* XXX: RFC2068 defines only SP and HT as whitespace, this test is
         * wrong... and so are many others probably.
         */
        while (apr_isspace(*value))
            ++value;            /* Skip to start of value   */

        /* should strip trailing whitespace as well */
        for (end = &value[strlen(value)-1]; end > value && apr_isspace(*end); --end)
            *end = '\0';

        /* make sure we add so as not to destroy duplicated headers
         * Modify headers requiring canonicalisation and/or affected
         * by ProxyPassReverse and family with process_proxy_header
         */
        process_proxy_header(r, dconf, buffer, value);
        saw_headers = 1;

        /* the header was too long; at the least we should skip extra data */
        if (len >= size - 1) {
            while ((len = ap_getline(field, MAX_STRING_LEN, rr, 1))
                    >= MAX_STRING_LEN - 1) {
                /* soak up the extra data */
            }
            if (len == 0) /* time to exit the larger loop as well */
                break;
        }
    }
}



static int addit_dammit(void *v, const char *key, const char *val)
{
    apr_table_addn(v, key, val);
    return 1;
}

static
apr_status_t ap_proxygetline(apr_bucket_brigade *bb, char *s, int n, request_rec *r,
                             int fold, int *writen)
{
    char *tmp_s = s;
    apr_status_t rv;
    apr_size_t len;

    rv = ap_rgetline(&tmp_s, n, &len, r, fold, bb);
    apr_brigade_cleanup(bb);

    if (rv == APR_SUCCESS) {
        *writen = (int) len;
    } else if (APR_STATUS_IS_ENOSPC(rv)) {
        *writen = n;
    } else {
        *writen = -1;
    }

    return rv;
}

/*
 * Limit the number of interim responses we sent back to the client. Otherwise
 * we suffer from a memory build up. Besides there is NO sense in sending back
 * an unlimited number of interim responses to the client. Thus if we cross
 * this limit send back a 502 (Bad Gateway).
 */
#ifndef AP_MAX_INTERIM_RESPONSES
#define AP_MAX_INTERIM_RESPONSES 10
#endif

static int add_trailers(void *data, const char *key, const char *val)
{
    if (val) {
        apr_table_add((apr_table_t*)data, key, val);
    }
    return 1;
}

static
apr_status_t ap_proxy_http_process_response(apr_pool_t * p, request_rec *r,
                                            proxy_conn_rec **backend_ptr,
                                            proxy_worker *worker,
                                            proxy_server_conf *conf,
                                            char *server_portstr) {
    conn_rec *c = r->connection;
    char buffer[HUGE_STRING_LEN];
    const char *buf;
    char keepchar;
    apr_bucket *e;
    apr_bucket_brigade *bb;
    apr_bucket_brigade *pass_bb;
    int len, backasswards;
    int interim_response = 0; /* non-zero whilst interim 1xx responses
                               * are being read. */
    int pread_len = 0;
    apr_table_t *save_table;
    int backend_broke = 0;
    static const char *hop_by_hop_hdrs[] =
        {"Keep-Alive", "Proxy-Authenticate", "TE", "Trailer", "Upgrade", NULL};
    int i;
    const char *te = NULL;
    int original_status = r->status;
    int proxy_status = OK;
    const char *original_status_line = r->status_line;
    const char *proxy_status_line = NULL;
    proxy_conn_rec *backend = *backend_ptr;
    conn_rec *origin = backend->connection;
    apr_interval_time_t old_timeout = 0;
    proxy_dir_conf *dconf;
    int do_100_continue;

    dconf = ap_get_module_config(r->per_dir_config, &proxy_module);

    do_100_continue = (worker->s->ping_timeout_set
                       && ap_request_has_body(r)
                       && (PROXYREQ_REVERSE == r->proxyreq)
                       && !(apr_table_get(r->subprocess_env, "force-proxy-request-1.0")));

    bb = apr_brigade_create(p, c->bucket_alloc);
    pass_bb = apr_brigade_create(p, c->bucket_alloc);

    /* Setup for 100-Continue timeout if appropriate */
    if (do_100_continue) {
        apr_socket_timeout_get(backend->sock, &old_timeout);
        if (worker->s->ping_timeout != old_timeout) {
            apr_status_t rc;
            rc = apr_socket_timeout_set(backend->sock, worker->s->ping_timeout);
            if (rc != APR_SUCCESS) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(01101)
                              "could not set 100-Continue timeout");
            }
        }
    }

    /* Get response from the remote server, and pass it up the
     * filter chain
     */

    backend->r = make_fake_req(origin, r);
    /* In case anyone needs to know, this is a fake request that is really a
     * response.
     */
    backend->r->proxyreq = PROXYREQ_RESPONSE;
    apr_table_setn(r->notes, "proxy-source-port", apr_psprintf(r->pool, "%hu",
                   origin->local_addr->port));
    do {
        apr_status_t rc;

        apr_brigade_cleanup(bb);

        rc = ap_proxygetline(backend->tmp_bb, buffer, sizeof(buffer),
                             backend->r, 0, &len);
        if (len == 0) {
            /* handle one potential stray CRLF */
            rc = ap_proxygetline(backend->tmp_bb, buffer, sizeof(buffer),
                                 backend->r, 0, &len);
        }
        if (len <= 0) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r, APLOGNO(01102)
                          "error reading status line from remote "
                          "server %s:%d", backend->hostname, backend->port);
            if (APR_STATUS_IS_TIMEUP(rc)) {
                apr_table_setn(r->notes, "proxy_timedout", "1");
                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01103) "read timeout");
                if (do_100_continue) {
                    return ap_proxyerror(r, HTTP_SERVICE_UNAVAILABLE, "Timeout on 100-Continue");
                }
            }
            /*
             * If we are a reverse proxy request shutdown the connection
             * WITHOUT ANY response to trigger a retry by the client
             * if allowed (as for idempotent requests).
             * BUT currently we should not do this if the request is the
             * first request on a keepalive connection as browsers like
             * seamonkey only display an empty page in this case and do
             * not do a retry. We should also not do this on a
             * connection which times out; instead handle as
             * we normally would handle timeouts
             */
            if (r->proxyreq == PROXYREQ_REVERSE && c->keepalives &&
                !APR_STATUS_IS_TIMEUP(rc)) {
                apr_bucket *eos;

                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01104)
                              "Closing connection to client because"
                              " reading from backend server %s:%d failed."
                              " Number of keepalives %i", backend->hostname,
                              backend->port, c->keepalives);
                ap_proxy_backend_broke(r, bb);
                /*
                 * Add an EOC bucket to signal the ap_http_header_filter
                 * that it should get out of our way, BUT ensure that the
                 * EOC bucket is inserted BEFORE an EOS bucket in bb as
                 * some resource filters like mod_deflate pass everything
                 * up to the EOS down the chain immediately and sent the
                 * remainder of the brigade later (or even never). But in
                 * this case the ap_http_header_filter does not get out of
                 * our way soon enough.
                 */
                e = ap_bucket_eoc_create(c->bucket_alloc);
                eos = APR_BRIGADE_LAST(bb);
                while ((APR_BRIGADE_SENTINEL(bb) != eos)
                       && !APR_BUCKET_IS_EOS(eos)) {
                    eos = APR_BUCKET_PREV(eos);
                }
                if (eos == APR_BRIGADE_SENTINEL(bb)) {
                    APR_BRIGADE_INSERT_TAIL(bb, e);
                }
                else {
                    APR_BUCKET_INSERT_BEFORE(eos, e);
                }
                ap_pass_brigade(r->output_filters, bb);
                /* Mark the backend connection for closing */
                backend->close = 1;
                /* Need to return OK to avoid sending an error message */
                return OK;
            }
            else if (!c->keepalives) {
                     ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01105)
                                   "NOT Closing connection to client"
                                   " although reading from backend server %s:%d"
                                   " failed.",
                                   backend->hostname, backend->port);
            }
            return ap_proxyerror(r, HTTP_BAD_GATEWAY,
                                 "Error reading from remote server");
        }
        /* XXX: Is this a real headers length send from remote? */
        backend->worker->s->read += len;

        /* Is it an HTTP/1 response?
         * This is buggy if we ever see an HTTP/1.10
         */
        if (apr_date_checkmask(buffer, "HTTP/#.# ###*")) {
            int major, minor;
            int toclose;

            major = buffer[5] - '0';
            minor = buffer[7] - '0';

            /* If not an HTTP/1 message or
             * if the status line was > 8192 bytes
             */
            if ((major != 1) || (len >= sizeof(buffer)-1)) {
                return ap_proxyerror(r, HTTP_BAD_GATEWAY,
                apr_pstrcat(p, "Corrupt status line returned by remote "
                            "server: ", buffer, NULL));
            }
            backasswards = 0;

            keepchar = buffer[12];
            buffer[12] = '\0';
            proxy_status = atoi(&buffer[9]);
            apr_table_setn(r->notes, "proxy-status",
                           apr_pstrdup(r->pool, &buffer[9]));

            if (keepchar != '\0') {
                buffer[12] = keepchar;
            } else {
                /* 2616 requires the space in Status-Line; the origin
                 * server may have sent one but ap_rgetline_core will
                 * have stripped it. */
                buffer[12] = ' ';
                buffer[13] = '\0';
            }
            proxy_status_line = apr_pstrdup(p, &buffer[9]);

            /* The status out of the front is the same as the status coming in
             * from the back, until further notice.
             */
            r->status = proxy_status;
            r->status_line = proxy_status_line;

            ap_log_rerror(APLOG_MARK, APLOG_TRACE3, 0, r,
                          "Status from backend: %d", proxy_status);

            /* read the headers. */
            /* N.B. for HTTP/1.0 clients, we have to fold line-wrapped headers*/
            /* Also, take care with headers with multiple occurences. */

            /* First, tuck away all already existing cookies */
            save_table = apr_table_make(r->pool, 2);
            apr_table_do(addit_dammit, save_table, r->headers_out,
                         "Set-Cookie", NULL);

            /* shove the headers direct into r->headers_out */
            ap_proxy_read_headers(r, backend->r, buffer, sizeof(buffer), origin,
                                  &pread_len);

            if (r->headers_out == NULL) {
                ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(01106)
                              "bad HTTP/%d.%d header returned by %s (%s)",
                              major, minor, r->uri, r->method);
                backend->close = 1;
                /*
                 * ap_send_error relies on a headers_out to be present. we
                 * are in a bad position here.. so force everything we send out
                 * to have nothing to do with the incoming packet
                 */
                r->headers_out = apr_table_make(r->pool,1);
                r->status = HTTP_BAD_GATEWAY;
                r->status_line = "bad gateway";
                return r->status;
            }

            /* Now, add in the just read cookies */
            apr_table_do(addit_dammit, save_table, r->headers_out,
                         "Set-Cookie", NULL);

            /* and now load 'em all in */
            if (!apr_is_empty_table(save_table)) {
                apr_table_unset(r->headers_out, "Set-Cookie");
                r->headers_out = apr_table_overlay(r->pool,
                                                   r->headers_out,
                                                   save_table);
            }

            /* can't have both Content-Length and Transfer-Encoding */
            if (apr_table_get(r->headers_out, "Transfer-Encoding")
                    && apr_table_get(r->headers_out, "Content-Length")) {
                /*
                 * 2616 section 4.4, point 3: "if both Transfer-Encoding
                 * and Content-Length are received, the latter MUST be
                 * ignored";
                 *
                 * To help mitigate HTTP Splitting, unset Content-Length
                 * and shut down the backend server connection
                 * XXX: We aught to treat such a response as uncachable
                 */
                apr_table_unset(r->headers_out, "Content-Length");
                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01107)
                              "server %s:%d returned Transfer-Encoding"
                              " and Content-Length",
                              backend->hostname, backend->port);
                backend->close = 1;
            }

            /*
             * Save a possible Transfer-Encoding header as we need it later for
             * ap_http_filter to know where to end.
             */
            te = apr_table_get(r->headers_out, "Transfer-Encoding");

            /* strip connection listed hop-by-hop headers from response */
            toclose = ap_proxy_clear_connection_fn(r, r->headers_out);
            if (toclose) {
                backend->close = 1;
            }

            if ((buf = apr_table_get(r->headers_out, "Content-Type"))) {
                ap_set_content_type(r, apr_pstrdup(p, buf));
            }
            if (!ap_is_HTTP_INFO(proxy_status)) {
                ap_proxy_pre_http_request(origin, backend->r);
            }

            /* Clear hop-by-hop headers */
            for (i=0; hop_by_hop_hdrs[i]; ++i) {
                apr_table_unset(r->headers_out, hop_by_hop_hdrs[i]);
            }

            /* Delete warnings with wrong date */
            r->headers_out = ap_proxy_clean_warnings(p, r->headers_out);

            /* handle Via header in response */
            if (conf->viaopt != via_off && conf->viaopt != via_block) {
                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:" response header entry and merge it */
                apr_table_addn(r->headers_out, "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)
                );
            }

            /* cancel keepalive if HTTP/1.0 or less */
            if ((major < 1) || (minor < 1)) {
                backend->close = 1;
                origin->keepalive = AP_CONN_CLOSE;
            }
        } else {
            /* an http/0.9 response */
            backasswards = 1;
            r->status = 200;
            r->status_line = "200 OK";
            backend->close = 1;
        }

        if (ap_is_HTTP_INFO(proxy_status)) {
            interim_response++;
            /* Reset to old timeout iff we've adjusted it */
            if (do_100_continue
                && (r->status == HTTP_CONTINUE)
                && (worker->s->ping_timeout != old_timeout)) {
                    apr_socket_timeout_set(backend->sock, old_timeout);
            }
        }
        else {
            interim_response = 0;
        }
        if (interim_response) {
            /* RFC2616 tells us to forward this.
             *
             * OTOH, an interim response here may mean the backend
             * is playing sillybuggers.  The Client didn't ask for
             * it within the defined HTTP/1.1 mechanisms, and if
             * it's an extension, it may also be unsupported by us.
             *
             * There's also the possibility that changing existing
             * behaviour here might break something.
             *
             * So let's make it configurable.
             *
             * We need to set "r->expecting_100 = 1" otherwise origin
             * server behaviour will apply.
             */
            const char *policy = apr_table_get(r->subprocess_env,
                                               "proxy-interim-response");
            ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r,
                          "HTTP: received interim %d response", r->status);
            if (!policy
                    || (!strcasecmp(policy, "RFC") && ((r->expecting_100 = 1)))) {
                ap_send_interim_response(r, 1);
            }
            /* FIXME: refine this to be able to specify per-response-status
             * policies and maybe also add option to bail out with 502
             */
            else if (strcasecmp(policy, "Suppress")) {
                ap_log_rerror(APLOG_MARK, APLOG_WARNING, 0, r, APLOGNO(01108)
                              "undefined proxy interim response policy");
            }
        }
        /* Moved the fixups of Date headers and those affected by
         * ProxyPassReverse/etc from here to ap_proxy_read_headers
         */

        if ((proxy_status == 401) && (dconf->error_override)) {
            const char *buf;
            const char *wa = "WWW-Authenticate";
            if ((buf = apr_table_get(r->headers_out, wa))) {
                apr_table_set(r->err_headers_out, wa, buf);
            } else {
                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01109)
                              "origin server sent 401 without "
                              "WWW-Authenticate header");
            }
        }

        r->sent_bodyct = 1;
        /*
         * Is it an HTTP/0.9 response or did we maybe preread the 1st line of
         * the response? If so, load the extra data. These are 2 mutually
         * exclusive possibilities, that just happen to require very
         * similar behavior.
         */
        if (backasswards || pread_len) {
            apr_ssize_t cntr = (apr_ssize_t)pread_len;
            if (backasswards) {
                /*@@@FIXME:
                 * At this point in response processing of a 0.9 response,
                 * we don't know yet whether data is binary or not.
                 * mod_charset_lite will get control later on, so it cannot
                 * decide on the conversion of this buffer full of data.
                 * However, chances are that we are not really talking to an
                 * HTTP/0.9 server, but to some different protocol, therefore
                 * the best guess IMHO is to always treat the buffer as "text/x":
                 */
                ap_xlate_proto_to_ascii(buffer, len);
                cntr = (apr_ssize_t)len;
            }
            e = apr_bucket_heap_create(buffer, cntr, NULL, c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(bb, e);
        }
        /* PR 41646: get HEAD right with ProxyErrorOverride */
        if (ap_is_HTTP_ERROR(r->status) && dconf->error_override) {
            /* clear r->status for override error, otherwise ErrorDocument
             * thinks that this is a recursive error, and doesn't find the
             * custom error page
             */
            r->status = HTTP_OK;
            /* Discard body, if one is expected */
            if (!r->header_only && /* not HEAD request */
                (proxy_status != HTTP_NO_CONTENT) && /* not 204 */
                (proxy_status != HTTP_NOT_MODIFIED)) { /* not 304 */
                const char *tmp;
                /* Add minimal headers needed to allow http_in filter
                 * detecting end of body without waiting for a timeout. */
                if ((tmp = apr_table_get(r->headers_out, "Transfer-Encoding"))) {
                    apr_table_set(backend->r->headers_in, "Transfer-Encoding", tmp);
                }
                else if ((tmp = apr_table_get(r->headers_out, "Content-Length"))) {
                    apr_table_set(backend->r->headers_in, "Content-Length", tmp);
                }
                else if (te) {
                    apr_table_set(backend->r->headers_in, "Transfer-Encoding", te);
                }
                ap_discard_request_body(backend->r);
            }
            /*
             * prevent proxy_handler() from treating this as an
             * internal error.
             */
            apr_table_setn(r->notes, "proxy-error-override", "1");
            return proxy_status;
        }

        /* send body - but only if a body is expected */
        if ((!r->header_only) &&                   /* not HEAD request */
            !interim_response &&                   /* not any 1xx response */
            (proxy_status != HTTP_NO_CONTENT) &&      /* not 204 */
            (proxy_status != HTTP_NOT_MODIFIED)) {    /* not 304 */

            /* We need to copy the output headers and treat them as input
             * headers as well.  BUT, we need to do this before we remove
             * TE, so that they are preserved accordingly for
             * ap_http_filter to know where to end.
             */
            backend->r->headers_in = apr_table_clone(backend->r->pool, r->headers_out);
            /*
             * Restore Transfer-Encoding header from response if we saved
             * one before and there is none left. We need it for the
             * ap_http_filter. See above.
             */
            if (te && !apr_table_get(backend->r->headers_in, "Transfer-Encoding")) {
                apr_table_add(backend->r->headers_in, "Transfer-Encoding", te);
            }

            apr_table_unset(r->headers_out,"Transfer-Encoding");

            ap_log_rerror(APLOG_MARK, APLOG_TRACE3, 0, r, "start body send");

            /*
             * if we are overriding the errors, we can't put the content
             * of the page into the brigade
             */
            if (!dconf->error_override || !ap_is_HTTP_ERROR(proxy_status)) {
                /* read the body, pass it to the output filters */
                apr_read_type_e mode = APR_NONBLOCK_READ;
                int finish = FALSE;

                /* Handle the case where the error document is itself reverse
                 * proxied and was successful. We must maintain any previous
                 * error status so that an underlying error (eg HTTP_NOT_FOUND)
                 * doesn't become an HTTP_OK.
                 */
                if (dconf->error_override && !ap_is_HTTP_ERROR(proxy_status)
                        && ap_is_HTTP_ERROR(original_status)) {
                    r->status = original_status;
                    r->status_line = original_status_line;
                }

                do {
                    apr_off_t readbytes;
                    apr_status_t rv;

                    rv = ap_get_brigade(backend->r->input_filters, bb,
                                        AP_MODE_READBYTES, mode,
                                        conf->io_buffer_size);

                    /* ap_get_brigade will return success with an empty brigade
                     * for a non-blocking read which would block: */
                    if (mode == APR_NONBLOCK_READ
                        && (APR_STATUS_IS_EAGAIN(rv)
                            || (rv == APR_SUCCESS && APR_BRIGADE_EMPTY(bb)))) {
                        /* flush to the client and switch to blocking mode */
                        e = apr_bucket_flush_create(c->bucket_alloc);
                        APR_BRIGADE_INSERT_TAIL(bb, e);
                        if (ap_pass_brigade(r->output_filters, bb)
                            || c->aborted) {
                            backend->close = 1;
                            break;
                        }
                        apr_brigade_cleanup(bb);
                        mode = APR_BLOCK_READ;
                        continue;
                    }
                    else if (rv == APR_EOF) {
                        backend->close = 1;
                        break;
                    }
                    else if (rv != APR_SUCCESS) {
                        /* In this case, we are in real trouble because
                         * our backend bailed on us. Pass along a 502 error
                         * error bucket
                         */
                        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(01110)
                                      "error reading response");
                        ap_proxy_backend_broke(r, bb);
                        ap_pass_brigade(r->output_filters, bb);
                        backend_broke = 1;
                        backend->close = 1;
                        break;
                    }
                    /* next time try a non-blocking read */
                    mode = APR_NONBLOCK_READ;

                    if (!apr_is_empty_table(backend->r->trailers_in)) {
                        apr_table_do(add_trailers, r->trailers_out,
                                backend->r->trailers_in, NULL);
                        apr_table_clear(backend->r->trailers_in);
                    }

                    apr_brigade_length(bb, 0, &readbytes);
                    backend->worker->s->read += readbytes;
#if DEBUGGING
                    {
                    ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01111)
                                  "readbytes: %#x", readbytes);
                    }
#endif
                    /* sanity check */
                    if (APR_BRIGADE_EMPTY(bb)) {
                        break;
                    }

                    /* Switch the allocator lifetime of the buckets */
                    ap_proxy_buckets_lifetime_transform(r, bb, pass_bb);

                    /* found the last brigade? */
                    if (APR_BUCKET_IS_EOS(APR_BRIGADE_LAST(pass_bb))) {

                        /* signal that we must leave */
                        finish = TRUE;

                        /* the brigade may contain transient buckets that contain
                         * data that lives only as long as the backend connection.
                         * Force a setaside so these transient buckets become heap
                         * buckets that live as long as the request.
                         */
                        for (e = APR_BRIGADE_FIRST(pass_bb); e
                                != APR_BRIGADE_SENTINEL(pass_bb); e
                                = APR_BUCKET_NEXT(e)) {
                            apr_bucket_setaside(e, r->pool);
                        }

                        /* finally it is safe to clean up the brigade from the
                         * connection pool, as we have forced a setaside on all
                         * buckets.
                         */
                        apr_brigade_cleanup(bb);

                        /* make sure we release the backend connection as soon
                         * as we know we are done, so that the backend isn't
                         * left waiting for a slow client to eventually
                         * acknowledge the data.
                         */
                        ap_proxy_release_connection(backend->worker->s->scheme,
                                backend, r->server);
                        /* Ensure that the backend is not reused */
                        *backend_ptr = NULL;

                    }

                    /* try send what we read */
                    if (ap_pass_brigade(r->output_filters, pass_bb) != APR_SUCCESS
                        || c->aborted) {
                        /* Ack! Phbtt! Die! User aborted! */
                        /* Only close backend if we haven't got all from the
                         * backend. Furthermore if *backend_ptr is NULL it is no
                         * longer safe to fiddle around with backend as it might
                         * be already in use by another thread.
                         */
                        if (*backend_ptr) {
                            backend->close = 1;  /* this causes socket close below */
                        }
                        finish = TRUE;
                    }

                    /* make sure we always clean up after ourselves */
                    apr_brigade_cleanup(pass_bb);
                    apr_brigade_cleanup(bb);

                } while (!finish);
            }
            ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r, "end body send");
        }
        else if (!interim_response) {
            ap_log_rerror(APLOG_MARK, APLOG_TRACE2, 0, r, "header only");

            /* make sure we release the backend connection as soon
             * as we know we are done, so that the backend isn't
             * left waiting for a slow client to eventually
             * acknowledge the data.
             */
            ap_proxy_release_connection(backend->worker->s->scheme,
                    backend, r->server);
            *backend_ptr = NULL;

            /* Pass EOS bucket down the filter chain. */
            e = apr_bucket_eos_create(c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(bb, e);
            ap_pass_brigade(r->output_filters, bb);

            apr_brigade_cleanup(bb);
        }
    } while (interim_response && (interim_response < AP_MAX_INTERIM_RESPONSES));

    /* We have to cleanup bb brigade, because buckets inserted to it could be
     * created from scpool and this pool can be freed before this brigade. */
    apr_brigade_cleanup(bb);

    /* See define of AP_MAX_INTERIM_RESPONSES for why */
    if (interim_response >= AP_MAX_INTERIM_RESPONSES) {
        return ap_proxyerror(r, HTTP_BAD_GATEWAY,
                             apr_psprintf(p,
                             "Too many (%d) interim responses from origin server",
                             interim_response));
    }

    /* If our connection with the client is to be aborted, return DONE. */
    if (c->aborted || backend_broke) {
        return DONE;
    }

    return OK;
}

static
apr_status_t ap_proxy_http_cleanup(const char *scheme, request_rec *r,
                                   proxy_conn_rec *backend)
{
    ap_proxy_release_connection(scheme, backend, r->server);
    return OK;
}

/*
 * This handles http:// URLs, and other URLs using a remote proxy over http
 * If proxyhost is NULL, then contact the server directly, otherwise
 * go via the proxy.
 * Note that if a proxy is used, then URLs other than http: can be accessed,
 * also, if we have trouble which is clearly specific to the proxy, then
 * we return DECLINED so that we can try another proxy. (Or the direct
 * route.)
 */
static int proxy_http_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];
    char *scheme;
    const char *proxy_function;
    const char *u;
    proxy_conn_rec *backend = NULL;
    int is_ssl = 0;
    conn_rec *c = r->connection;
    int retry = 0;
    /*
     * Use a shorter-lived pool to reduce memory usage
     * and avoid a memory leak
     */
    apr_pool_t *p = r->pool;
    apr_uri_t *uri = apr_palloc(p, sizeof(*uri));

    /* find the scheme */
    u = strchr(url, ':');
    if (u == NULL || u[1] != '/' || u[2] != '/' || u[3] == '\0')
       return DECLINED;
    if ((u - url) > 14)
        return HTTP_BAD_REQUEST;
    scheme = apr_pstrmemdup(p, url, u - url);
    /* scheme is lowercase */
    ap_str_tolower(scheme);
    /* is it for us? */
    if (strcmp(scheme, "https") == 0) {
        if (!ap_proxy_ssl_enable(NULL)) {
            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01112)
                          "HTTPS: declining URL %s (mod_ssl not configured?)",
                          url);
            return DECLINED;
        }
        is_ssl = 1;
        proxy_function = "HTTPS";
    }
    else if (!(strcmp(scheme, "http") == 0 || (strcmp(scheme, "ftp") == 0 && proxyname))) {
        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(01113) "HTTP: declining URL %s",
                      url);
        return DECLINED; /* only interested in HTTP, or FTP via proxy */
    }
    else {
        if (*scheme == 'h')
            proxy_function = "HTTP";
        else
            proxy_function = "FTP";
    }
    ap_log_rerror(APLOG_MARK, APLOG_TRACE1, 0, r, "HTTP: serving URL %s", url);


    /* create space for state information */
    if ((status = ap_proxy_acquire_connection(proxy_function, &backend,
                                              worker, r->server)) != OK)
        goto cleanup;

    backend->is_ssl = is_ssl;

    /*
     * In the case that we are handling a reverse proxy connection and this
     * is not a request that is coming over an already kept alive connection
     * with the client, do NOT reuse the connection to the backend, because
     * we cannot forward a failure to the client in this case as the client
     * does NOT expect this in this situation.
     * Yes, this creates a performance penalty.
     */
    if ((r->proxyreq == PROXYREQ_REVERSE) && (!c->keepalives)
        && (apr_table_get(r->subprocess_env, "proxy-initial-not-pooled"))) {
        backend->close = 1;
    }

    while (retry < 2) {
        char *locurl = url;

        /* Step One: Determine Who To Connect To */
        if ((status = ap_proxy_determine_connection(p, r, conf, worker, backend,
                                                uri, &locurl, proxyname,
                                                proxyport, server_portstr,
                                                sizeof(server_portstr))) != OK)
            break;

        /* Step Two: Make the Connection */
        if (ap_proxy_check_connection(proxy_function, backend, r->server, 1,
                                      PROXY_CHECK_CONN_EMPTY)
                && ap_proxy_connect_backend(proxy_function, backend, worker,
                                            r->server)) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01114)
                          "HTTP: 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(proxy_function, backend,
                                                     c, r->server)) != OK)
                break;
            /*
             * On SSL connections set a note on the connection what CN is
             * requested, such that mod_ssl can check if it is requested to do
             * so.
             */
            if (backend->ssl_hostname) {
                apr_table_setn(backend->connection->notes,
                               "proxy-request-hostname",
                               backend->ssl_hostname);
            }
        }

        /* Step Four: Send the Request
         * On the off-chance that we forced a 100-Continue as a
         * kinda HTTP ping test, allow for retries
         */
        if ((status = ap_proxy_http_request(p, r, backend, worker,
                                        conf, uri, locurl, server_portstr)) != OK) {
            if ((status == HTTP_SERVICE_UNAVAILABLE) && worker->s->ping_timeout_set) {
                backend->close = 1;
                ap_log_rerror(APLOG_MARK, APLOG_INFO, status, r, APLOGNO(01115)
                              "HTTP: 100-Continue failed to %pI (%s)",
                              worker->cp->addr, worker->s->hostname);
                retry++;
                continue;
            } else {
                break;
            }

        }

        /* Step Five: Receive the Response... Fall thru to cleanup */
        status = ap_proxy_http_process_response(p, r, &backend, worker,
                                                conf, server_portstr);

        break;
    }

    /* Step Six: Clean Up */
cleanup:
    if (backend) {
        if (status != OK)
            backend->close = 1;
        ap_proxy_http_cleanup(proxy_function, r, backend);
    }
    return status;
}