ngx_http_upstream.c

Nginx是一个高性能的HTTP和反向代理服务器

    c->log->action = "sending request to upstream";

    rc = ngx_output_chain(&u->output, u->request_sent ? NULL : u->request_bufs);

    u->request_sent = 1;

    if (rc == NGX_ERROR) {
        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
        return;
    }

    if (c->write->timer_set) {
        ngx_del_timer(c->write);
    }

    if (rc == NGX_AGAIN) {
        ngx_add_timer(c->write, u->conf->send_timeout);

        if (ngx_handle_write_event(c->write, u->conf->send_lowat) == NGX_ERROR)
        {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }

        return;
    }

    /* rc == NGX_OK */

    if (c->tcp_nopush == NGX_TCP_NOPUSH_SET) {
        if (ngx_tcp_push(c->fd) == NGX_ERROR) {
            ngx_log_error(NGX_LOG_CRIT, c->log, ngx_socket_errno,
                          ngx_tcp_push_n " failed");
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }

        c->tcp_nopush = NGX_TCP_NOPUSH_UNSET;
    }

    ngx_add_timer(c->read, u->conf->read_timeout);

#if 1
    if (c->read->ready) {

        /* post aio operation */

        /*
         * TODO comment
         * although we can post aio operation just in the end
         * of ngx_http_upstream_connect() CHECK IT !!!
         * it's better to do here because we postpone header buffer allocation
         */

        ngx_http_upstream_process_header(c->read);
        return;
    }
#endif

    c->write->handler = ngx_http_upstream_dummy_handler;

    if (ngx_handle_write_event(c->write, 0) == NGX_ERROR) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
    }
}


static void
ngx_http_upstream_send_request_handler(ngx_event_t *wev)
{
    ngx_connection_t     *c;
    ngx_http_request_t   *r;
    ngx_http_upstream_t  *u;

    c = wev->data;
    r = c->data;
    u = r->upstream;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, wev->log, 0,
                   "http upstream send request handler");

    if (wev->timedout) {
        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_TIMEOUT);
        return;
    }

#if (NGX_HTTP_SSL)

    if (u->ssl && c->ssl == NULL) {
        ngx_http_upstream_ssl_init_connection(r, u, c);
        return;
    }

#endif

    if (u->header_sent) {
        wev->handler = ngx_http_upstream_dummy_handler;

        (void) ngx_handle_write_event(wev, 0);

        return;
    }

    ngx_http_upstream_send_request(r, u);
}


static void
ngx_http_upstream_process_header(ngx_event_t *rev)
{
    ssize_t                         n;
    ngx_int_t                       rc;
    ngx_str_t                      *uri, args;
    ngx_uint_t                      i, flags;
    ngx_list_part_t                *part;
    ngx_table_elt_t                *h;
    ngx_connection_t               *c;
    ngx_http_request_t             *r;
    ngx_http_upstream_t            *u;
    ngx_http_err_page_t            *err_page;
    ngx_http_core_loc_conf_t       *clcf;
    ngx_http_upstream_header_t     *hh;
    ngx_http_upstream_main_conf_t  *umcf;

    c = rev->data;
    r = c->data;
    u = r->upstream;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, rev->log, 0,
                   "http upstream process header");

    c->log->action = "reading response header from upstream";

    if (rev->timedout) {
        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_TIMEOUT);
        return;
    }

    if (!u->request_sent && ngx_http_upstream_test_connect(c) != NGX_OK) {
        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
        return;
    }

    if (u->buffer.start == NULL) {
        u->buffer.start = ngx_palloc(r->pool, u->conf->buffer_size);
        if (u->buffer.start == NULL) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }

        u->buffer.pos = u->buffer.start;
        u->buffer.last = u->buffer.start;
        u->buffer.end = u->buffer.start + u->conf->buffer_size;
        u->buffer.temporary = 1;

        u->buffer.tag = u->output.tag;

        if (ngx_list_init(&u->headers_in.headers, r->pool, 8,
                          sizeof(ngx_table_elt_t))
            != NGX_OK)
        {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }

#if 0
        if (u->cache) {
            u->buffer.pos += u->cache->ctx.header_size;
            u->buffer.last = u->buffer.pos;
        }
#endif
    }

    n = c->recv(c, u->buffer.last, u->buffer.end - u->buffer.last);

    if (n == NGX_AGAIN) {
#if 0
        ngx_add_timer(rev, u->read_timeout);
#endif

        if (ngx_handle_read_event(rev, 0) == NGX_ERROR) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }

        return;
    }

    if (n == 0) {
        ngx_log_error(NGX_LOG_ERR, rev->log, 0,
                      "upstream prematurely closed connection");
    }

    if (n == NGX_ERROR || n == 0) {
        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
        return;
    }

    u->buffer.last += n;

#if 0
    u->valid_header_in = 0;

    u->peer.cached = 0;
#endif

    rc = u->process_header(r);

    if (rc == NGX_AGAIN) {
#if 0
        ngx_add_timer(rev, u->read_timeout);
#endif

        if (u->buffer.pos == u->buffer.end) {
            ngx_log_error(NGX_LOG_ERR, rev->log, 0,
                          "upstream sent too big header");

            ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_INVALID_HEADER);
            return;
        }

        if (ngx_handle_read_event(rev, 0) == NGX_ERROR) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }

        return;
    }

    if (rc == NGX_HTTP_UPSTREAM_INVALID_HEADER) {
        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_INVALID_HEADER);
        return;
    }

    if (rc == NGX_ERROR) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
    }

    /* rc == NGX_OK */

    if (u->headers_in.status_n >= NGX_HTTP_BAD_REQUEST
        && r->subrequest_in_memory)
    {
        u->buffer.last = u->buffer.pos;
    }

    if (u->headers_in.status_n == NGX_HTTP_INTERNAL_SERVER_ERROR) {

        if (u->peer.tries > 1
            && (u->conf->next_upstream & NGX_HTTP_UPSTREAM_FT_HTTP_500))
        {
            ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_HTTP_500);
            return;
        }

#if (NGX_HTTP_CACHE)

        if (u->peer.tries == 0
            && u->stale
            && (u->conf->use_stale & NGX_HTTP_UPSTREAM_FT_HTTP_500))
        {
            ngx_http_upstream_finalize_request(r, u,
                                              ngx_http_send_cached_response(r));
            return;
        }

#endif
    }

    if (u->headers_in.status_n == NGX_HTTP_NOT_FOUND) {

        if (u->peer.tries > 1
            && u->conf->next_upstream & NGX_HTTP_UPSTREAM_FT_HTTP_404)
        {
            ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_HTTP_404);
            return;
        }

        if (u->conf->intercept_404) {
            ngx_http_upstream_finalize_request(r, u, NGX_HTTP_NOT_FOUND);
            return;
        }
    }


    if (u->headers_in.status_n >= NGX_HTTP_BAD_REQUEST
        && u->conf->intercept_errors)
    {
        clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

        if (clcf->error_pages) {

            err_page = clcf->error_pages->elts;
            for (i = 0; i < clcf->error_pages->nelts; i++) {
                if (err_page[i].status == (ngx_int_t) u->headers_in.status_n) {

                    if (u->headers_in.status_n == NGX_HTTP_UNAUTHORIZED) {

                        r->headers_out.www_authenticate =
                                        ngx_list_push(&r->headers_out.headers);

                        if (r->headers_out.www_authenticate == NULL) {
                            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
                            return;
                        }

                        *r->headers_out.www_authenticate =
                                               *u->headers_in.www_authenticate;
                    }

                    ngx_http_upstream_finalize_request(r, u,
                                                       u->headers_in.status_n);
                    return;
                }
            }
        }
    }

    umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);

    if (u->headers_in.x_accel_redirect) {

        ngx_http_upstream_finalize_request(r, u, NGX_DECLINED);

        part = &u->headers_in.headers.part;
        h = part->elts;

        for (i = 0; /* void */; i++) {

            if (i >= part->nelts) {
                if (part->next == NULL) {
                    break;
                }

                part = part->next;
                h = part->elts;
                i = 0;
            }

            hh = ngx_hash_find(&umcf->headers_in_hash, h[i].hash,
                               h[i].lowcase_key, h[i].key.len);

            if (hh && hh->redirect) {
                if (hh->copy_handler(r, &h[i], hh->conf) != NGX_OK) {
                    ngx_http_finalize_request(r,
                                              NGX_HTTP_INTERNAL_SERVER_ERROR);
                    return;
                }
            }
        }

        uri = &u->headers_in.x_accel_redirect->value;
        args.len = 0;
        args.data = NULL;
        flags = 0;

        if (ngx_http_parse_unsafe_uri(r, uri, &args, &flags) != NGX_OK) {
            ngx_http_finalize_request(r, NGX_HTTP_NOT_FOUND);
            return;
        }

        if (flags & NGX_HTTP_ZERO_IN_URI) {
            r->zero_in_uri = 1;
        }

        if (r->method != NGX_HTTP_HEAD) {
            r->method = NGX_HTTP_GET;
        }

        ngx_http_internal_redirect(r, uri, &args);
        return;
    }

    part = &u->headers_in.headers.part;
    h = part->elts;

    for (i = 0; /* void */; i++) {

        if (i >= part->nelts) {
            if (part->next == NULL) {
                break;
            }

            part = part->next;
            h = part->elts;
            i = 0;
        }

        if (ngx_hash_find(&u->conf->hide_headers_hash, h[i].hash,
                          h[i].lowcase_key, h[i].key.len))
        {
            continue;
        }

        hh = ngx_hash_find(&umcf->headers_in_hash, h[i].hash,
                           h[i].lowcase_key, h[i].key.len);

        if (hh) {
            if (hh->copy_handler(r, &h[i], hh->conf) != NGX_OK) {
                ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
                return;
            }

            continue;
        }

        if (ngx_http_upstream_copy_header_line(r, &h[i], 0) != NGX_OK) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }
    }

    if (r->headers_out.server && r->headers_out.server->value.data == NULL) {
        r->headers_out.server->hash = 0;
    }

    if (r->headers_out.date && r->headers_out.date->value.data == NULL) {
        r->headers_out.date->hash = 0;
    }

    r->headers_out.status = u->headers_in.status_n;
    r->headers_out.status_line = u->headers_in.status_line;

    u->headers_in.content_length_n = r->headers_out.content_length_n;

    if (r->headers_out.content_length_n != -1) {
        u->length = (size_t) r->headers_out.content_length_n;

    } else {
        u->length = NGX_MAX_SIZE_T_VALUE;
    }

    if (!r->subrequest_in_memory) {
        ngx_http_upstream_send_response(r, u);
        return;
    }

    /* subrequest content in memory */

    if (u->input_filter == NULL) {
        u->input_filter_init = ngx_http_upstream_non_buffered_filter_init;
        u->input_filter = ngx_http_upstream_non_buffered_filter;
        u->input_filter_ctx = r;
    }

    if (u->input_filter_init(u->input_filter_ctx) == NGX_ERROR) {