ngx_http_ajp_handler.c


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
#include <ngx_http_ajp.h>
#include <ngx_http_ajp_handler.h>


static ngx_int_t ngx_http_ajp_eval(ngx_http_request_t *r,
    ngx_http_ajp_loc_conf_t *alcf);
#if (NGX_HTTP_CACHE)
static ngx_int_t ngx_http_ajp_create_key(ngx_http_request_t *r);
#endif
static ngx_int_t ngx_http_ajp_create_request(ngx_http_request_t *r);
static ngx_int_t ngx_http_ajp_reinit_request(ngx_http_request_t *r);
static ngx_int_t ngx_http_ajp_process_header(ngx_http_request_t *r);
static ngx_int_t ngx_http_ajp_input_filter_init(void *data);
static ngx_int_t ngx_http_ajp_input_filter(ngx_event_pipe_t *p,
    ngx_buf_t *buf);
static void ngx_http_ajp_abort_request(ngx_http_request_t *r);
static void ngx_http_ajp_finalize_request(ngx_http_request_t *r,
    ngx_int_t rc);

static ngx_int_t ngx_http_upstream_send_request_body(ngx_http_request_t *r,
    ngx_http_upstream_t *u);
static ngx_chain_t *ajp_data_msg_send_body(ngx_http_request_t *r, size_t max_size,
    ngx_chain_t **body);
static void ngx_http_upstream_send_request_body_handler(ngx_http_request_t *r,
    ngx_http_upstream_t *u);
static void ngx_http_upstream_dummy_handler(ngx_http_request_t *r,
    ngx_http_upstream_t *u);

static ngx_int_t ngx_http_ajp_move_buffer(ngx_http_request_t *r, ngx_buf_t *buf,
    u_char *pos, u_char *last);
static ngx_int_t ngx_http_ajp_process_packet_header(ngx_http_request_t *r,
    ngx_http_ajp_ctx_t *a, ngx_buf_t *buf);
static void ngx_http_ajp_end_response(ngx_http_request_t *r, int reuse);


ngx_int_t
ngx_http_ajp_handler(ngx_http_request_t *r)
{
    ngx_int_t                 rc;
    ngx_http_upstream_t      *u;
    ngx_http_ajp_ctx_t       *a;
    ngx_http_ajp_loc_conf_t  *alcf;

    if (r->subrequest_in_memory) {
        ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                      "ngx_ajp_module does not support "
                      "subrequest in memory");
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    if (ngx_http_upstream_create(r) != NGX_OK) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    a = ngx_pcalloc(r->pool, sizeof(ngx_http_ajp_ctx_t));
    if (a == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    a->state = ngx_http_ajp_st_init_state;
    a->pstate = ngx_http_ajp_pst_init_state;

    ngx_http_set_ctx(r, a, ngx_http_ajp_module);

    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    if (alcf->ajp_lengths) {
        if (ngx_http_ajp_eval(r, alcf) != NGX_OK) {
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    }

    u = r->upstream;

    u->schema.len = sizeof("ajp://") - 1;
    u->schema.data = (u_char *) "ajp://";

    u->output.tag = (ngx_buf_tag_t) &ngx_http_ajp_module;

    u->conf = &alcf->upstream;

#if (NGX_HTTP_CACHE)
    u->create_key = ngx_http_ajp_create_key;
#endif
    u->create_request = ngx_http_ajp_create_request;
    u->reinit_request = ngx_http_ajp_reinit_request;
    u->process_header = ngx_http_ajp_process_header;
    u->abort_request = ngx_http_ajp_abort_request;
    u->finalize_request = ngx_http_ajp_finalize_request;

    u->buffering = 1;

    u->pipe = ngx_pcalloc(r->pool, sizeof(ngx_event_pipe_t));
    if (u->pipe == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    u->pipe->input_filter = ngx_http_ajp_input_filter;
    u->pipe->input_ctx = r;
    u->input_filter_init = ngx_http_ajp_input_filter_init;

    rc = ngx_http_read_client_request_body(r, ngx_http_upstream_init);

    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
        return rc;
    }

    return NGX_DONE;
}


static ngx_int_t
ngx_http_ajp_eval(ngx_http_request_t *r, ngx_http_ajp_loc_conf_t *alcf)
{
    ngx_url_t  u;

    ngx_memzero(&u, sizeof(ngx_url_t));

    if (ngx_http_script_run(r, &u.url, alcf->ajp_lengths->elts, 0,
                            alcf->ajp_values->elts)
        == NULL)
    {
        return NGX_ERROR;
    }

    u.no_resolve = 1;

    if (ngx_parse_url(r->pool, &u) != NGX_OK) {
         if (u.err) {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "%s in upstream \"%V\"", u.err, &u.url);
        }

        return NGX_ERROR;
    }

    if (u.no_port) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "no port in upstream \"%V\"", &u.url);
        return NGX_ERROR;
    }

    r->upstream->resolved = ngx_pcalloc(r->pool,
                                        sizeof(ngx_http_upstream_resolved_t));
    if (r->upstream->resolved == NULL) {
        return NGX_ERROR;
    }

    if (u.addrs && u.addrs[0].sockaddr) {
        r->upstream->resolved->sockaddr = u.addrs[0].sockaddr;
        r->upstream->resolved->socklen = u.addrs[0].socklen;
        r->upstream->resolved->naddrs = 1;
        r->upstream->resolved->host = u.addrs[0].name;

    } else {
        r->upstream->resolved->host = u.host;
        r->upstream->resolved->port = u.port;
    }

    return NGX_OK;
}


#if (NGX_HTTP_CACHE)

static ngx_int_t
ngx_http_ajp_create_key(ngx_http_request_t *r)
{
    ngx_str_t                *key;
    ngx_http_ajp_loc_conf_t  *alcf;

    key = ngx_array_push(&r->cache->keys);
    if (key == NULL) {
        return NGX_ERROR;
    }

    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    if (ngx_http_complex_value(r, &alcf->cache_key, key) != NGX_OK) {
        return NGX_ERROR;
    }

    return NGX_OK;
}

#endif


static ngx_int_t
ngx_http_ajp_create_request(ngx_http_request_t *r)
{
    ajp_msg_t                *msg;
    ngx_chain_t              *cl;
    ngx_http_ajp_ctx_t       *a;
    ngx_http_ajp_loc_conf_t  *alcf;

    a = ngx_http_get_module_ctx(r, ngx_http_ajp_module);
    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    if (a == NULL || alcf == NULL) {
        return NGX_ERROR;
    }

    msg = ajp_msg_reuse(&a->msg);

    if (NGX_OK != ajp_msg_create_buffer(r->pool,
                alcf->ajp_header_packet_buffer_size_conf, msg)) {
        return NGX_ERROR;
    }

    if (NGX_OK != ajp_marshal_into_msgb(msg, r, alcf)) {
        return NGX_ERROR;
    }

    ajp_msg_end(msg);

    cl = ngx_alloc_chain_link(r->pool);
    if (cl == NULL) {
        return NGX_ERROR;
    }

    cl->buf = msg->buf;
    cl->buf->flush = 1;

    a->state = ngx_http_ajp_st_forward_request_sent;

    if (alcf->upstream.pass_request_body) {
        a->body = r->upstream->request_bufs;
        r->upstream->request_bufs = cl;

        cl->next = ajp_data_msg_send_body(r,
                alcf->max_ajp_data_packet_size_conf, &a->body);

        if (a->body) {
            a->state = ngx_http_ajp_st_request_body_data_sending;
        }
        else {
            a->state = ngx_http_ajp_st_request_send_all_done;
        }

    } else {
        a->state = ngx_http_ajp_st_request_send_all_done;
        r->upstream->request_bufs = cl;
        cl->next = NULL;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_ajp_reinit_request(ngx_http_request_t *r)
{
    ngx_http_ajp_ctx_t       *a;
    ngx_http_ajp_loc_conf_t  *alcf;

    a = ngx_http_get_module_ctx(r, ngx_http_ajp_module);
    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    if (a == NULL || alcf == NULL) {
        return NGX_ERROR;
    }

    a->state = ngx_http_ajp_st_init_state;
    a->pstate = ngx_http_ajp_pst_init_state;
    a->length = 0;
    a->extra_zero_byte = 0;

    ajp_msg_reuse(&a->msg);

    a->body = NULL;

    return NGX_OK;
}


static ngx_list_t *
ngx_list_reinit(ngx_list_t *list)
{
    ngx_list_part_t  *head;

    head = &list->part;

    if (head->nelts > 0) {
        list->last = head;

        head->nelts = 0;
        head->next = NULL;
    }

    return list;
}


static ngx_int_t
ngx_http_ajp_process_header(ngx_http_request_t *r)
{
    u_char                   *pos, *last, type, reuse;
    uint16_t                  length;
    ngx_int_t                 rc;
    ngx_buf_t                *buf;
    ajp_msg_t                *msg;
    ngx_http_ajp_ctx_t       *a;
    ngx_http_upstream_t      *u;
    ngx_http_ajp_loc_conf_t  *alcf;

    a = ngx_http_get_module_ctx(r, ngx_http_ajp_module);
    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    if (a == NULL || alcf == NULL) {
        return NGX_ERROR;
    }

    ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
                  "ngx_http_ajp_process_header: state(%d)", a->state);

    u = r->upstream;

    msg = ajp_msg_reuse(&a->msg);
    buf = msg->buf = &u->buffer;

    while (buf->pos < buf->last) {

        ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
                      "ngx_http_ajp_process_header: parse response, "
                      "pos:%p, last:%p", buf->pos, buf->last);

        /* save the position for returning NGX_AGAIN */
        pos = buf->pos;
        last = buf->last;

        if (ngx_buf_size(msg->buf) < AJP_HEADER_LEN + 1) {
            return ngx_http_ajp_move_buffer(r, buf, pos, last);
        }

        rc = ajp_msg_parse_begin(msg);
        if (rc != NGX_OK) {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "ngx_http_ajp_process_header: bad header\n"
                          "%s", ajp_msg_dump(r->pool, msg, "bad header"));

            return NGX_ERROR;
        }

        rc = ajp_msg_get_uint8(msg, (u_char *)&type);
        if (rc != NGX_OK) {
            return NGX_ERROR;
        }

        switch (type) {
            case CMD_AJP13_GET_BODY_CHUNK:

                rc = ajp_msg_get_uint16(msg, &length);
                if (rc == AJP_EOVERFLOW) {
                    return ngx_http_ajp_move_buffer(r, buf, pos, last);
                }

                rc = ngx_http_upstream_send_request_body(r, u);
                if (rc != NGX_OK) {
                    return rc;
                }

                break;

            case CMD_AJP13_SEND_HEADERS:

                rc = ajp_unmarshal_response(msg, r, alcf);

                if (rc == NGX_OK) {
                    a->state = ngx_http_ajp_st_response_parse_headers_done;
                    return NGX_OK;

                } else if (rc == AJP_EOVERFLOW) {
                    a->state = ngx_http_ajp_st_response_recv_headers;

                    /* reinit the headers_int list, the memory may be stale */
                    ngx_list_reinit(&u->headers_in.headers);

                    /* It's an uncomplete AJP packet, move back to the header
                     * of packet, and parse the header again in next call
                     */
                    return ngx_http_ajp_move_buffer(r, buf, pos, last);

                } else {
                    return  NGX_ERROR;
                }

                break;

            case CMD_AJP13_SEND_BODY_CHUNK:

                buf->pos = pos;
                a->state = ngx_http_ajp_st_response_body_data_sending;

                /* input_filter function will process these data */
                return NGX_OK;

            case CMD_AJP13_END_RESPONSE:

                rc = ajp_msg_get_uint8(msg, &reuse);
                if (rc == AJP_EOVERFLOW) {
                    return ngx_http_ajp_move_buffer(r, buf, pos, last);
                }

                ngx_http_ajp_end_response(r, reuse);

                buf->last_buf = 1;
                return NGX_OK;

            default:

                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "ngx_http_ajp_process_header: "
                              "bad_packet_type(%d)\n%s",
                              type, ajp_msg_dump(r->pool, msg, "bad type"));

                return  NGX_ERROR;
        }
    }

    return NGX_AGAIN;
}


static ngx_int_t
ngx_http_ajp_input_filter_init(void *data)
{
    ngx_http_request_t  *r = data;

    r->upstream->pipe->length = (off_t) AJP_HEADER_LEN;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ajp_move_buffer(ngx_http_request_t *r, ngx_buf_t *buf,
    u_char *pos, u_char *last)
{
    /* Move the end part data to the head of buffer, reuse the buffer. */
    ngx_log_error(NGX_LOG_WARN, r->connection->log, 0,
                  "ngx_http_ajp_process_header: move buffer for the ajp "
                  "packet.\n");

    /*
     * The first buffer, there should have enough buffer room.
     */
    if (buf->last == buf->end) {
        buf->pos = buf->start;
        buf->last = buf->start + (last - pos);

        if (buf->last > pos ) {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "ngx_http_ajp_process_header: too small buffer for "
                          "the ajp packet.\n");

            return NGX_ERROR;
        }

        ngx_memcpy(buf->pos, pos, last - pos);

    } else {
        /*
         * Back to the orginal postion.
         */
        buf->pos = pos;
    }

    return NGX_AGAIN;
}


static ngx_int_t
ngx_http_upstream_send_request_body(ngx_http_request_t *r,
    ngx_http_upstream_t *u)
{
    ngx_int_t                  rc;
    ngx_chain_t               *cl;
    ajp_msg_t                 *msg, local_msg;
    ngx_connection_t          *c;
    ngx_http_ajp_ctx_t        *a;
    ngx_http_ajp_loc_conf_t   *alcf;

    c = u->peer.connection;

    a = ngx_http_get_module_ctx(r, ngx_http_ajp_module);
    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    if (a->state > ngx_http_ajp_st_request_body_data_sending) {
        ngx_log_error(NGX_LOG_WARN, r->connection->log, 0,
                      "ngx_http_upstream_send_request_body: bad state(%d)",
                      a->state);
    }

    cl = ajp_data_msg_send_body(r, alcf->max_ajp_data_packet_size_conf,
                                &a->body);

    if (u->output.in == NULL && u->output.busy == NULL) {
        if (cl == NULL) {
            /* If there is no more data in the body (i.e. the servlet
             * container is trying to read past the end of the body),
             * the server will send back an "empty" packet, which is
             * a body packet with a payload length of 0.
             * (0x12,0x34,0x00,0x00)
             */
            msg = ajp_msg_reuse(&local_msg);

            if (ajp_alloc_data_msg(r->pool, msg) != NGX_OK) {
                return NGX_ERROR;
            }

            ajp_data_msg_end(msg, 0);

            cl = ngx_alloc_chain_link(r->pool);
            if (cl == NULL) {
                return NGX_ERROR;
            }

            cl->buf = msg->buf;
            cl->next = NULL;
        }
    }

    if (a->body) {
        a->state = ngx_http_ajp_st_request_body_data_sending;

    } else {
        a->state = ngx_http_ajp_st_request_send_all_done;
    }

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

    rc = ngx_output_chain(&u->output, cl);

    if (rc == NGX_ERROR) {
        return NGX_ERROR;
    }

    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_OK) {
            return NGX_ERROR;
        }

        u->write_event_handler = ngx_http_upstream_send_request_body_handler;

        return NGX_AGAIN;
    }

    /* 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");
            return NGX_ERROR;
        }

        c->tcp_nopush = NGX_TCP_NOPUSH_UNSET;
    }

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

    if (ngx_handle_write_event(c->write, 0) != NGX_OK) {
        return NGX_ERROR;
    }

    u->write_event_handler = ngx_http_upstream_dummy_handler;

    return NGX_OK;
}


ngx_chain_t *
ajp_data_msg_send_body(ngx_http_request_t *r, size_t max_size,
    ngx_chain_t **body)
{
    size_t               size;
    ngx_buf_t           *b_in, *b_out;
    ajp_msg_t           *msg;
    ngx_chain_t         *out, *cl, *in;
    ngx_http_ajp_ctx_t  *a;

    a = ngx_http_get_module_ctx(r, ngx_http_ajp_module);

    if (*body == NULL || a == NULL) {
        return NULL;
    }

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "ajp_data_msg_send_body");

    msg = ajp_msg_reuse(&a->msg);

    if (ajp_alloc_data_msg(r->pool, msg) != NGX_OK) {
        return NULL;
    }

    out = cl = ngx_alloc_chain_link(r->pool);
    if (cl == NULL) {
        return NULL;
    }

    cl->buf = msg->buf;

    max_size -= AJP_HEADER_SZ;
    size = 0;
    in = *body;

    b_out = NULL;
    while (in) {
        b_in = in->buf;

        b_out = ngx_alloc_buf(r->pool);
        if (b_out == NULL) {
            return NULL;
        }
        ngx_memcpy(b_out, b_in, sizeof(ngx_buf_t));

        if (b_in->in_file) {
            if ((size_t)(b_in->file_last - b_in->file_pos) <=
                (max_size - size)) {

                b_out->file_pos = b_in->file_pos;
                b_out->file_last = b_in->file_pos = b_in->file_last;

                size += (size_t) b_out->file_last - (size_t) b_out->file_pos;

            } else if ((size_t)(b_in->file_last - b_in->file_pos) >
                       (max_size - size)) {

                b_out->file_pos = b_in->file_pos;
                b_in->file_pos += max_size - size;
                b_out->file_last = b_in->file_pos;

                size += (size_t) b_out->file_last - (size_t) b_out->file_pos;
            }

        } else {
            if ((size_t)(b_in->last - b_in->pos) <= (max_size - size)) {
                b_out->pos = b_in->pos;
                b_out->last = b_in->pos = b_in->last;

                size += b_out->last - b_out->pos;

            } else if ((size_t)(b_in->last - b_in->pos) > (max_size - size)) {
                b_out->pos = b_in->pos;
                b_in->pos += max_size - size;
                b_out->last = b_in->pos;

                size += b_out->last - b_out->pos;
            }
        }

        cl->next = ngx_alloc_chain_link(r->pool);
        if (cl->next == NULL) {
            return NULL;
        }

        cl = cl->next;
        cl->buf = b_out;

        if (size >= max_size) {
            break;

        } else {
            in = in->next;
        }
    }

    *body = in;
    cl->next = NULL;

    ajp_data_msg_end(msg, size);

    return out;
}


static void
ngx_http_upstream_send_request_body_handler(ngx_http_request_t *r,
    ngx_http_upstream_t *u)
{
    ngx_int_t rc;

    rc = ngx_http_upstream_send_request_body(r, u);

    if (rc == NGX_ERROR) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "ngx_http_upstream_send_request_body error");
    }
}


static void
ngx_http_upstream_dummy_handler(ngx_http_request_t *r,
    ngx_http_upstream_t *u)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "ajp upstream dummy handler");
    return;
}


static ngx_int_t
ngx_http_ajp_input_filter(ngx_event_pipe_t *p, ngx_buf_t *buf)
{
    ngx_int_t                 rc;
    ngx_buf_t                *b, **prev;
    ngx_chain_t              *cl;
    ngx_http_request_t       *r;
    ngx_http_ajp_ctx_t       *a;
    ngx_http_ajp_loc_conf_t  *alcf;

    if (buf->pos == buf->last) {
        return NGX_OK;
    }

    r = p->input_ctx;
    a = ngx_http_get_module_ctx(r, ngx_http_ajp_module);
    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    ngx_log_error(NGX_LOG_DEBUG, r->connection->log, 0,
                  "ngx_http_ajp_input_filter: state(%d)", a->state);

    b = NULL;
    prev = &buf->shadow;

    while(buf->pos < buf->last) {

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, p->log, 0,
                       "input filter packet, begin length: %z, buffer_size: %z",
                       a->length, ngx_buf_size(buf));

        /* This a new data packet */
        if (a->length == 0) {

            if (a->extra_zero_byte) {
                if (*(buf->pos) == 0x00){
                    buf->pos++;
                }

                a->extra_zero_byte = 0;
            }

            rc = ngx_http_ajp_process_packet_header(r, a, buf);

            if (buf->pos == buf->last) {
                break;
            }

            if (rc == NGX_AGAIN) {
                break;
            }

            if (rc == NGX_DONE) {
                break;
            }

            if (rc == NGX_ERROR) {
                return NGX_ERROR;
            }

        }

        /* Get a zero length packet */
        if (a->length == 0) {

            if (a->extra_zero_byte && (buf->pos < buf->last)
                && (*(buf->pos) == 0x00))
            {
                buf->pos++;
                a->extra_zero_byte = 0;
            }

            continue;
        }

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, p->log, 0,
                       "input filter packet, length:%z, buffer_size:%z",
                       a->length, ngx_buf_size(buf));

        if (p->free) {
            b = p->free->buf;
            p->free = p->free->next;

        } else {
            b = ngx_alloc_buf(p->pool);
            if (b == NULL) {
                return NGX_ERROR;
            }
        }

        ngx_memzero(b, sizeof(ngx_buf_t));

        b->pos = buf->pos;
        b->start = buf->start;
        b->end = buf->end;
        b->tag = p->tag;
        b->temporary = 1;
        b->recycled = 1;

        *prev = b;
        prev = &b->shadow;

        cl = ngx_alloc_chain_link(p->pool);
        if (cl == NULL) {
            return NGX_ERROR;
        }

        cl->buf = b;
        cl->next = NULL;

        if (p->in) {
            *p->last_in = cl;
        } else {
            p->in = cl;
        }
        p->last_in = &cl->next;

        /* STUB */ b->num = buf->num;

        if (buf->pos + a->length < buf->last) {
            buf->pos += a->length;
            b->last = buf->pos;

            a->length = 0;
        }
        else {
            a->length -= buf->last - buf->pos;
            buf->pos = buf->last;
            b->last = buf->last;
        }

        if (b->pos == b->last) {
            b->sync = 1;
        }

        if ((a->length == 0) && a->extra_zero_byte &&
            (buf->pos < buf->last) && (*(buf->pos) == 0x00)) {

            /* The last byte of this message always seems to be
             * 0x00 and is not part of the chunk.
             */
            buf->pos++;
            a->extra_zero_byte = 0;
        }

        ngx_log_debug3(NGX_LOG_DEBUG_EVENT, p->log, 0,
                       "input buf #%d %p size: %z",
                       b->num, b->pos, b->last - b->pos);
    }

    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, p->log, 0,
                   "free buf %p %z", buf->pos, ngx_buf_size(buf));

    if (alcf->keep_conn) {
        /* set p->length, minimal amount of data we want to see */
        if (!a->length) {
            p->length = 1;
        } else {
            p->length = a->length;
        }

        if (p->upstream_done) {
            p->length = 0;
        }
    }

    if (b) {
        b->shadow = buf;
        b->last_shadow = 1;

        ngx_log_debug2(NGX_LOG_DEBUG_EVENT, p->log, 0,
                       "input buf %p %z", b->pos, ngx_buf_size(buf));

        return NGX_OK;
    }

    /* there is no data record in the buf, add it to free chain */

    if (ngx_event_pipe_add_free_buf(p, buf) != NGX_OK) {
        return NGX_ERROR;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_ajp_process_packet_header(ngx_http_request_t *r,
    ngx_http_ajp_ctx_t *a, ngx_buf_t *buf)
{
    int                            reuse;
    u_char                         ch;
    ngx_http_ajp_packet_state_e    state;

    state = a->pstate;

    while(buf->pos < buf->last) {

        ch = *buf->pos++;
        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "http ajp packet header pstate: %d, byte: %02Xd",
                       state, ch);

        switch (state) {

        case ngx_http_ajp_pst_init_state:
            if (ch != 0x41) {
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "upstream sent unexpected AJP "
                              "preamble1: %d", ch);

                return NGX_ERROR;
            }

            state = ngx_http_ajp_pst_preamble1;
            break;

        case ngx_http_ajp_pst_preamble1:
            if (ch != 0x42) {
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "upstream sent unexpected AJP "
                              "preamble2: %d", ch);

                return NGX_ERROR;
            }

            state = ngx_http_ajp_pst_preamble2;
            break;

        case ngx_http_ajp_pst_preamble2:
            /* Not record the payload length */
            state = ngx_http_ajp_pst_payload_length_hi;
            break;

        case ngx_http_ajp_pst_payload_length_hi:
            state = ngx_http_ajp_pst_payload_length_lo;
            break;

        case ngx_http_ajp_pst_payload_length_lo:
            if (ch == CMD_AJP13_SEND_BODY_CHUNK) {
                state = ngx_http_ajp_pst_data_length_hi;

            } else if (ch == CMD_AJP13_END_RESPONSE) {
                state = ngx_http_ajp_pst_end_response;

            } else {
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "upstream sent unexpected AJP "
                              "type: %d", ch);

                return NGX_ERROR;
            }

            break;

        case ngx_http_ajp_pst_end_response:
            if (ch == 0x01) {
                reuse = 1;
            } else {
                reuse = 0;
            }

            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "ngx_http_ajp_end_response: reuse=%d", reuse);

            ngx_http_ajp_end_response(r, reuse);
            a->pstate = ngx_http_ajp_pst_init_state;

            return NGX_DONE;

        case ngx_http_ajp_pst_data_length_hi:
            a->length_hi = ch;
            state = ngx_http_ajp_pst_data_length_lo;

            break;

        case ngx_http_ajp_pst_data_length_lo:
            a->length = (a->length_hi << 8) + ch;

            a->pstate = ngx_http_ajp_pst_init_state;
            a->length_hi = 0x00;
            a->extra_zero_byte = 1;

            return NGX_OK;
        }
    }

    a->pstate = state;

    return NGX_AGAIN;
}


static void
ngx_http_ajp_end_response(ngx_http_request_t *r, int reuse)
{
    ngx_event_pipe_t          *p;
    ngx_http_ajp_ctx_t        *a;
    ngx_http_ajp_loc_conf_t   *alcf;

    a = ngx_http_get_module_ctx(r, ngx_http_ajp_module);
    alcf = ngx_http_get_module_loc_conf(r, ngx_http_ajp_module);

    if (a == NULL || alcf == NULL) {
        return;
    }

    p = r->upstream->pipe;

    a->ajp_reuse = reuse;
    if (alcf->keep_conn && reuse) {
        r->upstream->keepalive = 1;
    }
    p->upstream_done = 1;
    a->state = ngx_http_ajp_st_response_end;
}


static void
ngx_http_ajp_abort_request(ngx_http_request_t *r)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "abort http ajp request");
    return;
}


static void
ngx_http_ajp_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "finalize http ajp request");

    return;
}