ngx_http_upstream.c

Nginx是一个高性能的HTTP和反向代理服务器

        ngx_resolve_name_done(ctx);
        ngx_http_finalize_request(r, NGX_HTTP_BAD_GATEWAY);
        return;
    }

    ur = r->upstream->resolved;
    ur->naddrs = ctx->naddrs;
    ur->addrs = ctx->addrs;

#if (NGX_DEBUG)
    {
    in_addr_t   addr;
    ngx_uint_t  i;

    for (i = 0; i < ctx->naddrs; i++) {
        addr = ntohl(ur->addrs[i]);

        ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "name was resolved to %ud.%ud.%ud.%ud",
                       (addr >> 24) & 0xff, (addr >> 16) & 0xff,
                       (addr >> 8) & 0xff, addr & 0xff);
    }
    }
#endif

    if (ngx_http_upstream_create_round_robin_peer(r, ur) != NGX_OK) {
        ngx_resolve_name_done(ctx);
        ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
    }

    ngx_resolve_name_done(ctx);

    ngx_http_upstream_connect(r, r->upstream);
}


static void
ngx_http_upstream_rd_check_broken_connection(ngx_http_request_t *r)
{
    ngx_http_upstream_check_broken_connection(r, r->connection->read);
}


static void
ngx_http_upstream_wr_check_broken_connection(ngx_http_request_t *r)
{
    ngx_http_upstream_check_broken_connection(r, r->connection->write);
}


static void
ngx_http_upstream_check_broken_connection(ngx_http_request_t *r,
    ngx_event_t *ev)
{
    int                  n;
    char                 buf[1];
    ngx_err_t            err;
    ngx_connection_t     *c;
    ngx_http_upstream_t  *u;

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ev->log, 0,
                   "http upstream check client, write event:%d, \"%V\"",
                   ev->write, &r->uri);

    c = r->connection;
    u = r->upstream;

    if (c->error) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_CLIENT_CLOSED_REQUEST);
        return;
    }

    if (u->peer.connection == NULL) {
        return;
    }

#if (NGX_HAVE_KQUEUE)

    if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {

        if (!ev->pending_eof) {
            return;
        }

        ev->eof = 1;
        c->error = 1;

        if (ev->kq_errno) {
            ev->error = 1;
        }

        if (!u->cacheable && !u->store && u->peer.connection) {
            ngx_log_error(NGX_LOG_INFO, ev->log, ev->kq_errno,
                          "kevent() reported that client closed prematurely "
                          "connection, so upstream connection is closed too");
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_CLIENT_CLOSED_REQUEST);
            return;
        }

        ngx_log_error(NGX_LOG_INFO, ev->log, ev->kq_errno,
                      "kevent() reported that client closed "
                      "prematurely connection");

        if (u->peer.connection == NULL) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_CLIENT_CLOSED_REQUEST);
            return;
        }

        return;
    }

#endif

    n = recv(c->fd, buf, 1, MSG_PEEK);

    err = ngx_socket_errno;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ev->log, err,
                   "http upstream recv(): %d", n);

    /*
     * we do not need to disable the write event because
     * that event has NGX_USE_CLEAR_EVENT type
     */

    if (ev->write && (n >= 0 || err == NGX_EAGAIN)) {
        return;
    }

    if ((ngx_event_flags & NGX_USE_LEVEL_EVENT) && ev->active) {
        if (ngx_del_event(ev, NGX_READ_EVENT, 0) == NGX_ERROR) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }
    }

    if (n > 0) {
        return;
    }

    if (n == -1) {
        if (err == NGX_EAGAIN) {
            return;
        }

        ev->error = 1;

    } else { /* n == 0 */
        err = 0;
    }

    ev->eof = 1;
    c->error = 1;

    if (!u->cacheable && !u->store && u->peer.connection) {
        ngx_log_error(NGX_LOG_INFO, ev->log, err,
                      "client closed prematurely connection, "
                      "so upstream connection is closed too");
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_CLIENT_CLOSED_REQUEST);
        return;
    }

    ngx_log_error(NGX_LOG_INFO, ev->log, err,
                  "client closed prematurely connection");

    if (u->peer.connection == NULL) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_CLIENT_CLOSED_REQUEST);
        return;
    }
}


static void
ngx_http_upstream_connect(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
    ngx_int_t          rc;
    ngx_time_t        *tp;
    ngx_connection_t  *c;

    r->connection->log->action = "connecting to upstream";

    r->connection->single_connection = 0;

    if (u->state && u->state->response_sec) {
        tp = ngx_timeofday();
        u->state->response_sec = tp->sec - u->state->response_sec;
        u->state->response_msec = tp->msec - u->state->response_msec;
    }

    u->state = ngx_array_push(r->upstream_states);
    if (u->state == NULL) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
    }

    ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));

    tp = ngx_timeofday();
    u->state->response_sec = tp->sec;
    u->state->response_msec = tp->msec;

    rc = ngx_event_connect_peer(&u->peer);

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http upstream connect: %i", rc);

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

    u->state->peer = u->peer.name;

    if (rc == NGX_BUSY) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "no live upstreams");
        ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_NOLIVE);
        return;
    }

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

    /* rc == NGX_OK || rc == NGX_AGAIN */

    c = u->peer.connection;

    c->data = r;

    c->write->handler = ngx_http_upstream_send_request_handler;
    c->read->handler = ngx_http_upstream_process_header;

    c->sendfile &= r->connection->sendfile;
    u->output.sendfile = c->sendfile;

    c->pool = r->pool;
    c->read->log = c->write->log = c->log = r->connection->log;

    /* init or reinit the ngx_output_chain() and ngx_chain_writer() contexts */

    u->writer.out = NULL;
    u->writer.last = &u->writer.out;
    u->writer.connection = c;
    u->writer.limit = 0;

    if (u->request_sent) {
        if (ngx_http_upstream_reinit(r, u) != NGX_OK) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }
    }

    if (r->request_body
        && r->request_body->buf
        && r->request_body->temp_file
        && r == r->main)
    {
        /*
         * the r->request_body->buf can be reused for one request only,
         * the subrequests should allocate their own temporay bufs
         */

        u->output.free = ngx_alloc_chain_link(r->pool);
        if (u->output.free == NULL) {
            ngx_http_upstream_finalize_request(r, u,
                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
            return;
        }

        u->output.free->buf = r->request_body->buf;
        u->output.free->next = NULL;
        u->output.allocated = 1;

        r->request_body->buf->pos = r->request_body->buf->start;
        r->request_body->buf->last = r->request_body->buf->start;
        r->request_body->buf->tag = u->output.tag;
    }

    u->request_sent = 0;

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

#if (NGX_HTTP_SSL)

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

#endif

    ngx_http_upstream_send_request(r, u);
}


#if (NGX_HTTP_SSL)

static void
ngx_http_upstream_ssl_init_connection(ngx_http_request_t *r,
    ngx_http_upstream_t *u, ngx_connection_t *c)
{
    ngx_int_t   rc;

    if (ngx_ssl_create_connection(u->conf->ssl, c,
                                  NGX_SSL_BUFFER|NGX_SSL_CLIENT)
        == NGX_ERROR)
    {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
    }

    c->sendfile = 0;
    u->output.sendfile = 0;

    if (u->peer.set_session(&u->peer, u->peer.data) != NGX_OK) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
    }

    r->connection->log->action = "SSL handshaking to upstream";

    rc = ngx_ssl_handshake(c);

    if (rc == NGX_AGAIN) {
        c->ssl->handler = ngx_http_upstream_ssl_handshake;
        return;
    }

    ngx_http_upstream_ssl_handshake(c);
}


static void
ngx_http_upstream_ssl_handshake(ngx_connection_t *c)
{
    ngx_http_request_t   *r;
    ngx_http_upstream_t  *u;

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

    if (c->ssl->handshaked) {

        u->peer.save_session(&u->peer, u->peer.data);

        c->write->handler = ngx_http_upstream_send_request_handler;
        c->read->handler = ngx_http_upstream_process_header;

        ngx_http_upstream_send_request(r, u);

        return;
    }

    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);

}

#endif


static ngx_int_t
ngx_http_upstream_reinit(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
    ngx_chain_t  *cl;

    if (u->reinit_request(r) != NGX_OK) {
        return NGX_ERROR;
    }

    ngx_memzero(&u->headers_in, sizeof(ngx_http_upstream_headers_in_t));

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

    /* reinit the request chain */

    for (cl = u->request_bufs; cl; cl = cl->next) {
        cl->buf->pos = cl->buf->start;
        cl->buf->file_pos = 0;
    }

    /* reinit the subrequest's ngx_output_chain() context */

    if (r->request_body && r->request_body->temp_file
        && r != r->main && u->output.buf)
    {
        u->output.free = ngx_alloc_chain_link(r->pool);
        if (u->output.free == NULL) {
            return NGX_ERROR;
        }

        u->output.free->buf = u->output.buf;
        u->output.free->next = NULL;

        u->output.buf->pos = u->output.buf->start;
        u->output.buf->last = u->output.buf->start;
    }

    u->output.buf = NULL;
    u->output.in = NULL;
    u->output.busy = NULL;

    /* reinit u->buffer */

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

    } else {
        u->buffer.pos = u->buffer.start;
        u->buffer.last = u->buffer.start;
    }
#else

        u->buffer.pos = u->buffer.start;
        u->buffer.last = u->buffer.start;

#endif

    return NGX_OK;
}


static void
ngx_http_upstream_send_request(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
    ngx_int_t          rc;
    ngx_connection_t  *c;

    c = u->peer.connection;

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

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