src/lib-http/http-server-request.c

	http-server-request.c revision 31300f53eadd34fc7bd567b2424565a60c06e2f5
2e37d45867d081db150ab78dad303b9077aea24fTimo Sirainen/* Copyright (c) 2013-2016 Dovecot authors, see the included COPYING file */
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen#include "lib.h"
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen#include "ioloop.h"
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen#include "ostream.h"
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen#include "istream-private.h"
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen#include "http-server-private.h"
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen/*
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen * Logging
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen */
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenstatic inline void
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenhttp_server_request_debug(struct http_server_request *req,
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    const char *format, ...) ATTR_FORMAT(2, 3);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenstatic inline void
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenhttp_server_request_debug(struct http_server_request *req,
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    const char *format, ...)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen{
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server *server = req->server;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    va_list args;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (server->set.debug) {
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        va_start(args, format);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        i_debug("http-server: request %s: %s",
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen            http_server_request_label(req),
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen            t_strdup_vprintf(format, args));
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        va_end(args);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    }
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen}
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen/*
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen * Request
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen */
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenstruct http_server_request *
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenhttp_server_request_new(struct http_server_connection *conn)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen{
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    static unsigned int id_counter = 0;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    pool_t pool;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server_request *req;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    pool = pool_alloconly_create(MEMPOOL_GROWING"http_server_request", 4096);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req = p_new(pool, struct http_server_request, 1);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->pool = pool;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->refcount = 1;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->conn = conn;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->server = conn->server;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->id = ++id_counter;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    http_server_connection_add_request(conn, req);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    return req;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen}
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenvoid http_server_request_ref(struct http_server_request *req)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen{
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    i_assert(req->refcount > 0);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->refcount++;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen}
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenbool http_server_request_unref(struct http_server_request **_req)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen{
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server_request *req = *_req;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server_connection *conn = req->conn;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    i_assert(req->refcount > 0);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    *_req = NULL;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (--req->refcount > 0)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        return TRUE;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    http_server_request_debug(req, "Free");
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (req->state < HTTP_SERVER_REQUEST_STATE_FINISHED) {
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        req->state = HTTP_SERVER_REQUEST_STATE_ABORTED;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        http_server_connection_remove_request(conn, req);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    }
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (req->destroy_callback != NULL) {
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        req->destroy_callback(req->destroy_context);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        req->destroy_callback = NULL;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    }
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (req->response != NULL)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        http_server_response_free(req->response);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    pool_unref(&req->pool);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    return FALSE;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen}
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenvoid http_server_request_destroy(struct http_server_request **_req)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen{
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server_request *req = *_req;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server *server = req->server;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    http_server_request_debug(req, "Destroy");
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    /* just make sure the request ends in a proper state */
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (req->state < HTTP_SERVER_REQUEST_STATE_FINISHED)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        req->state = HTTP_SERVER_REQUEST_STATE_ABORTED;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (server->ioloop)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        io_loop_stop(server->ioloop);
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (req->delay_destroy) {
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        req->destroy_pending = TRUE;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    } else if (req->destroy_callback != NULL) {
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        void (*callback)(void *) = req->destroy_callback;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        req->destroy_callback = NULL;
9a3da808c280163e69cc38639bf4931d0f83f7e3Timo Sirainen        callback(req->destroy_context);
9a3da808c280163e69cc38639bf4931d0f83f7e3Timo Sirainen    }
9a3da808c280163e69cc38639bf4931d0f83f7e3Timo Sirainen    http_server_request_unref(_req);
9a3da808c280163e69cc38639bf4931d0f83f7e3Timo Sirainen}
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenvoid http_server_request_set_destroy_callback(struct http_server_request *req,
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen                          void (*callback)(void *),
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen                          void *context)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen{
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->destroy_callback = callback;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    req->destroy_context = context;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen}
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainenvoid http_server_request_abort(struct http_server_request **_req,
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    const char *reason)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen{
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server_request *req = *_req;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    struct http_server_connection *conn = req->conn;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    if (req->state >= HTTP_SERVER_REQUEST_STATE_FINISHED)
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen        return;
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen
8871c97974dd4e682c7b8d5cff0bbc5b024f56f2Timo Sirainen    http_server_request_debug(req, "Abort");

    req->conn = NULL;
    if (req->state < HTTP_SERVER_REQUEST_STATE_FINISHED) {
        if (conn != NULL) {
            http_server_connection_remove_request(conn, req);

            if (!conn->closed) {
                /* send best-effort response if appropriate */
                if (!conn->output_locked &&
                    req->state >= HTTP_SERVER_REQUEST_STATE_PROCESSING &&
                    req->state < HTTP_SERVER_REQUEST_STATE_SENT_RESPONSE) {
                    static const char *response =
                        "HTTP/1.1 500 Internal Server Error\r\n"
                        "Content-Length: 0\r\n"
                        "\r\n";

                    (void)o_stream_send(conn->conn.output,
                        response, strlen(response));
                }

                /* close the connection */
                http_server_connection_close(&conn, reason);
            }
        }

        req->state = HTTP_SERVER_REQUEST_STATE_ABORTED;
    }

    if (req->response != NULL &&
        !req->response->payload_blocking) {
        http_server_response_free(req->response);
        req->response = NULL;
    }

    http_server_request_destroy(_req);
}

const struct http_request *
http_server_request_get(struct http_server_request *req)
{
    return &req->req;
}

pool_t
http_server_request_get_pool(struct http_server_request *req)
{
    return req->pool;
}

struct http_server_response *
http_server_request_get_response(struct http_server_request *req)
{
    return req->response;
}

int http_server_request_get_auth(struct http_server_request *req,
    struct http_auth_credentials *credentials)
{
    const char *auth;

    auth = http_request_header_get(&req->req, "Authorization");
    if (auth == NULL)
        return 0;

    if (http_auth_parse_credentials
        ((const unsigned char *)auth, strlen(auth), credentials) < 0)
        return -1;

    return 1;
}

bool http_server_request_is_finished(struct http_server_request *req)
{
    return req->response != NULL ||
        req->state == HTTP_SERVER_REQUEST_STATE_ABORTED;
}

void http_server_request_halt_payload(struct http_server_request *req)
{
    i_assert(req->state <= HTTP_SERVER_REQUEST_STATE_QUEUED);
    req->payload_halted = TRUE;
}

void http_server_request_continue_payload(struct http_server_request *req)
{
    i_assert(req->state <= HTTP_SERVER_REQUEST_STATE_QUEUED);
    req->payload_halted = FALSE;
    if (req->req.expect_100_continue && !req->sent_100_continue)
        http_server_connection_trigger_responses(req->conn);
}

void http_server_request_ready_to_respond(struct http_server_request *req)
{
    http_server_request_debug(req, "Ready to respond");

    req->state = HTTP_SERVER_REQUEST_STATE_READY_TO_RESPOND;
    http_server_connection_trigger_responses(req->conn);
}

void http_server_request_submit_response(struct http_server_request *req)
{
    struct http_server_connection *conn = req->conn;

    i_assert(conn != NULL && req->response != NULL && req->response->submitted);

    switch (req->state) {
    case HTTP_SERVER_REQUEST_STATE_NEW:
    case HTTP_SERVER_REQUEST_STATE_QUEUED:
    case HTTP_SERVER_REQUEST_STATE_PAYLOAD_IN:
    case HTTP_SERVER_REQUEST_STATE_PROCESSING:
        if (!http_server_request_is_complete(req)) {
            http_server_request_debug(req, "Not ready to respond");
            req->state = HTTP_SERVER_REQUEST_STATE_SUBMITTED_RESPONSE;
            break;
        }
        http_server_request_ready_to_respond(req);
        break;
    case HTTP_SERVER_REQUEST_STATE_ABORTED:
        break;
    default:
        i_unreached();
    }
}

void http_server_request_finished(struct http_server_request *req)
{
    struct http_server_connection *conn = req->conn;
    struct http_server_response *resp = req->response;
    http_server_tunnel_callback_t tunnel_callback = resp->tunnel_callback;
    void *tunnel_context = resp->tunnel_context;

    http_server_request_debug(req, "Finished");

    i_assert(req->state < HTTP_SERVER_REQUEST_STATE_FINISHED);
    req->state = HTTP_SERVER_REQUEST_STATE_FINISHED;

    http_server_connection_remove_request(conn, req);
    conn->stats.response_count++;

    if (tunnel_callback == NULL && (req->req.connection_close || resp->close)) {
        if (resp->close) {
            http_server_connection_close(&conn,
                t_strdup_printf("Server closed connection: %u %s",
                    resp->status, resp->reason));

        } else {
            http_server_connection_close(&conn,
                "Client requested connection close");
        }
        http_server_request_destroy(&req);
        return;
    }

    http_server_request_destroy(&req);
    if (tunnel_callback != NULL) {
        http_server_connection_tunnel(&conn, tunnel_callback, tunnel_context);
        return;
    }

    http_server_connection_trigger_responses(conn);
}

static  struct http_server_response *
http_server_request_create_fail_response(struct http_server_request *req,
    unsigned int status, const char *reason)
{
    struct http_server_response *resp;

    req->failed = TRUE;

    resp = http_server_response_create(req, status, reason);
    http_server_response_add_header
        (resp, "Content-Type", "text/plain; charset=utf-8");
    reason = t_strconcat(reason, "\r\n", NULL);
    http_server_response_set_payload_data
        (resp, (const unsigned char *)reason, strlen(reason));

    return resp;
}

static void
http_server_request_fail_full(struct http_server_request *req,
    unsigned int status, const char *reason, bool close)
{
    struct http_server_response *resp;

    req->failed = TRUE;
    resp = http_server_request_create_fail_response(req, status, reason);
    if (close)
        http_server_response_submit_close(resp);
    else
        http_server_response_submit(resp);
}

void http_server_request_fail(struct http_server_request *req,
    unsigned int status, const char *reason)
{
    http_server_request_fail_full(req, status, reason,
                      req->conn->input_broken);
}

void http_server_request_fail_close(struct http_server_request *req,
    unsigned int status, const char *reason)
{
    http_server_request_fail_full(req, status, reason, TRUE);
}

void http_server_request_fail_auth(struct http_server_request *req,
    const char *reason, const struct http_auth_challenge *chlng)
{
    struct http_server_response *resp;

    req->failed = TRUE;

    if (reason == NULL)
        reason = "Unauthenticated";

    resp = http_server_request_create_fail_response(req, 401, reason);
    http_server_response_add_auth(resp, chlng);
    http_server_response_submit(resp);
}

void http_server_request_fail_auth_basic(struct http_server_request *req,
    const char *reason, const char *realm)
{
    struct http_auth_challenge chlng;

    http_auth_basic_challenge_init(&chlng, realm);
    http_server_request_fail_auth(req, reason, &chlng);
}

/*
 * Payload input stream
 */

struct http_server_istream {
    struct istream_private istream;

    struct http_server_request *req;

    ssize_t read_status;
};

static void
http_server_istream_switch_ioloop(struct istream_private *stream)
{
    struct http_server_istream *hsristream =
        (struct http_server_istream *)stream;

    if (hsristream->istream.istream.blocking)
        return;

    http_server_connection_switch_ioloop(hsristream->req->conn);
}

static void
http_server_istream_read_any(struct http_server_istream *hsristream)
{
    struct istream_private *stream = &hsristream->istream;
    struct http_server *server = hsristream->req->server;
    ssize_t ret;

    if ((ret=i_stream_read_copy_from_parent
        (&stream->istream)) > 0) {
        hsristream->read_status = ret;
        io_loop_stop(server->ioloop);
    }
}

static ssize_t
http_server_istream_read(struct istream_private *stream)
{
    struct http_server_istream *hsristream =
        (struct http_server_istream *)stream;
    struct http_server_request *req = hsristream->req;
    struct http_server *server;
    struct http_server_connection *conn;
    bool blocking = stream->istream.blocking;
    ssize_t ret;

    if (req == NULL) {
        /* request already gone (we shouldn't get here) */
        stream->istream.stream_errno = EINVAL;
        return -1;
    }

    i_stream_seek(stream->parent, stream->parent_start_offset +
              stream->istream.v_offset);

    server = hsristream->req->server;
    conn = hsristream->req->conn;

    ret = i_stream_read_copy_from_parent(&stream->istream);
    if (ret == 0 && blocking) {
        struct ioloop *prev_ioloop = current_ioloop;
        struct io *io;

        http_server_connection_ref(conn);
        http_server_request_ref(req);

        i_assert(server->ioloop == NULL);
        server->ioloop = io_loop_create();
        http_server_connection_switch_ioloop(conn);

        if (blocking && req->req.expect_100_continue &&
            !req->sent_100_continue)
            http_server_connection_trigger_responses(conn);

        hsristream->read_status = 0;
        io = io_add_istream(&stream->istream,
            http_server_istream_read_any, hsristream);
        while (req->state < HTTP_SERVER_REQUEST_STATE_FINISHED &&
            hsristream->read_status == 0) {
            io_loop_run(server->ioloop);
        }
        io_remove(&io);

        io_loop_set_current(prev_ioloop);
        http_server_connection_switch_ioloop(conn);
        io_loop_set_current(server->ioloop);
        io_loop_destroy(&server->ioloop);

        ret = hsristream->read_status;

        if (!http_server_request_unref(&req))
            hsristream->req = NULL;
        http_server_connection_unref(&conn);
    }

    return ret;
}

static void
http_server_istream_destroy(struct iostream_private *stream)
{
    struct http_server_istream *hsristream =
        (struct http_server_istream *)stream;
    uoff_t v_offset;

    v_offset = hsristream->istream.parent_start_offset +
        hsristream->istream.istream.v_offset;
    if (hsristream->istream.parent->seekable ||
        v_offset > hsristream->istream.parent->v_offset) {
        /* get to same position in parent stream */
        i_stream_seek(hsristream->istream.parent, v_offset);
    }

    i_stream_unref(&hsristream->istream.parent);
}

struct istream *
http_server_request_get_payload_input(struct http_server_request *req,
    bool blocking)
{
    struct http_server_istream *hsristream;
    struct istream *payload = req->req.payload;

    i_assert(req->payload_input == NULL);

    hsristream = i_new(struct http_server_istream, 1);
    hsristream->req = req;
    hsristream->istream.max_buffer_size =
        payload->real_stream->max_buffer_size;
    hsristream->istream.stream_size_passthrough = TRUE;

    hsristream->istream.read = http_server_istream_read;
    hsristream->istream.switch_ioloop = http_server_istream_switch_ioloop;
    hsristream->istream.iostream.destroy = http_server_istream_destroy;

    hsristream->istream.istream.readable_fd = FALSE;
    hsristream->istream.istream.blocking = blocking;
    hsristream->istream.istream.seekable = FALSE;

    req->payload_input = i_stream_create
        (&hsristream->istream, payload, i_stream_get_fd(payload));
    i_stream_unref(&req->req.payload);
    return req->payload_input;
}