mod_proxy_http.c

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

    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;

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

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

    rp = ap_proxy_make_fake_req(origin, r);
    /* In case anyone needs to know, this is a fake request that is really a
     * response.
     */
    rp->proxyreq = PROXYREQ_RESPONSE;
    tmp_bb = apr_brigade_create(p, c->bucket_alloc);
    do {
        apr_status_t rc;

        apr_brigade_cleanup(bb);

        rc = ap_proxygetline(tmp_bb, buffer, sizeof(buffer), rp, 0, &len);
        if (len == 0) {
            /* handle one potential stray CRLF */
            rc = ap_proxygetline(tmp_bb, buffer, sizeof(buffer), rp, 0, &len);
        }
        if (len <= 0) {
            ap_log_rerror(APLOG_MARK, APLOG_ERR, rc, r,
                          "proxy: error reading status line from remote "
                          "server %s", backend->hostname);
            if (rc == APR_TIMEUP) {
                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                              "proxy: read timeout");
            }
            /*
             * 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 &&
                rc != APR_TIMEUP) {
                apr_bucket *eos;

                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
                              "proxy: Closing connection to client because"
                              " reading from backend server %s failed. Number"
                              " of keepalives %i", backend->hostname, 
                              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);
                /* 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,
                                   "proxy: NOT Closing connection to client"
                                   " although reading from backend server %s"
                                   " failed.", backend->hostname);
            }
            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;

            if (2 != sscanf(buffer, "HTTP/%u.%u", &major, &minor)) {
                major = 1;
                minor = 1;
            }
            /* If not an HTTP/1 message or
             * if the status line was > 8192 bytes
             */
            else if ((buffer[5] != '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';
            r->status = atoi(&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';
            }
            r->status_line = apr_pstrdup(p, &buffer[9]);


            /* 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, rp, buffer, sizeof(buffer), origin,
                                  &pread_len);

            if (r->headers_out == NULL) {
                ap_log_error(APLOG_MARK, APLOG_WARNING, 0,
                             r->server, "proxy: 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_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
                             "proxy: server %s returned Transfer-Encoding"
                             " and Content-Length", backend->hostname);
                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 */
            backend->close += ap_proxy_liststr(apr_table_get(r->headers_out,
                                                             "Connection"),
                                              "close");
            ap_proxy_clear_connection(p, r->headers_out);
            if ((buf = apr_table_get(r->headers_out, "Content-Type"))) {
                ap_set_content_type(r, apr_pstrdup(p, buf));
            }
            if (!ap_is_HTTP_INFO(r->status)) {
                ap_proxy_pre_http_request(origin, rp);
            }

            /* 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(r->status)) {
            interim_response++;
        }
        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.
             */
            const char *policy = apr_table_get(r->subprocess_env,
                                               "proxy-interim-response");
            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL,
                         "proxy: HTTP: received interim %d response",
                         r->status);
            if (!policy || !strcasecmp(policy, "RFC")) {
                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_error(APLOG_MARK, APLOG_WARNING, 0, NULL,
                             "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 ((r->status == 401) && (conf->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_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
                             "proxy: 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);
        }

        /* send body - but only if a body is expect