multithread stability

[platform/upstream/libwebsockets.git] / lib / libwebsockets.c

/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010-2016 Andy Green <andy@warmcat.com>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation:
 *  version 2.1 of the License.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA  02110-1301  USA
 */

#include "private-libwebsockets.h"

int log_level = LLL_ERR | LLL_WARN | LLL_NOTICE;
static void (*lwsl_emit)(int level, const char *line) = lwsl_emit_stderr;

static const char * const log_level_names[] = {
        "ERR",
        "WARN",
        "NOTICE",
        "INFO",
        "DEBUG",
        "PARSER",
        "HEADER",
        "EXTENSION",
        "CLIENT",
        "LATENCY",
};

void
lws_free_wsi(struct lws *wsi)
{
        if (!wsi)
                return;

        /* Protocol user data may be allocated either internally by lws
         * or by specified the user.
         * We should only free what we allocated. */
        if (wsi->protocol && wsi->protocol->per_session_data_size &&
            wsi->user_space && !wsi->user_space_externally_allocated)
                lws_free(wsi->user_space);

        lws_free_set_NULL(wsi->rxflow_buffer);
        lws_free_set_NULL(wsi->trunc_alloc);
        /*
         * These union members have an ah at the start
         *
         *      struct _lws_http_mode_related http;
         *      struct _lws_http2_related http2;
         *      struct _lws_header_related hdr;
         *
         * basically ws-related union member does not
         */
        if (wsi->mode != LWSCM_WS_CLIENT &&
            wsi->mode != LWSCM_WS_SERVING)
                lws_free_header_table(wsi);

        lws_free(wsi);
}

static void
lws_remove_from_timeout_list(struct lws *wsi)
{
        struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];

        if (!wsi->timeout_list_prev)
                return;

        lws_pt_lock(pt);
        if (wsi->timeout_list)
                wsi->timeout_list->timeout_list_prev = wsi->timeout_list_prev;
        *wsi->timeout_list_prev = wsi->timeout_list;

        wsi->timeout_list_prev = NULL;
        wsi->timeout_list = NULL;
        lws_pt_unlock(pt);
}

/**
 * lws_set_timeout() - marks the wsi as subject to a timeout
 *
 * You will not need this unless you are doing something special
 *
 * @wsi:        Websocket connection instance
 * @reason:     timeout reason
 * @secs:       how many seconds
 */

LWS_VISIBLE void
lws_set_timeout(struct lws *wsi, enum pending_timeout reason, int secs)
{
        struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
        time_t now;

        lws_pt_lock(pt);

        time(&now);

        if (!wsi->pending_timeout && reason) {
                wsi->timeout_list = pt->timeout_list;
                if (wsi->timeout_list)
                        wsi->timeout_list->timeout_list_prev = &wsi->timeout_list;
                wsi->timeout_list_prev = &pt->timeout_list;
                *wsi->timeout_list_prev = wsi;
        }

        wsi->pending_timeout_limit = now + secs;
        wsi->pending_timeout = reason;

        lws_pt_unlock(pt);

        if (!reason)
                lws_remove_from_timeout_list(wsi);
}

void
lws_close_free_wsi(struct lws *wsi, enum lws_close_status reason)
{
        struct lws_context *context;
        struct lws_context_per_thread *pt;
        int n, m, ret;
        struct lws_tokens eff_buf;

        if (!wsi)
                return;

        context = wsi->context;
        pt = &context->pt[(int)wsi->tsi];

        if (wsi->mode == LWSCM_HTTP_SERVING_ACCEPTED &&
            wsi->u.http.fd != LWS_INVALID_FILE) {
                lwsl_debug("closing http file\n");
                lws_plat_file_close(wsi, wsi->u.http.fd);
                wsi->u.http.fd = LWS_INVALID_FILE;
                context->protocols[0].callback(wsi, LWS_CALLBACK_CLOSED_HTTP,
                                               wsi->user_space, NULL, 0);
        }
        if (wsi->socket_is_permanently_unusable ||
            reason == LWS_CLOSE_STATUS_NOSTATUS_CONTEXT_DESTROY ||
            wsi->state == LWSS_SHUTDOWN)
                goto just_kill_connection;

        wsi->state_pre_close = wsi->state;

        switch (wsi->state_pre_close) {
        case LWSS_DEAD_SOCKET:
                return;

        /* we tried the polite way... */
        case LWSS_AWAITING_CLOSE_ACK:
                goto just_kill_connection;

        case LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE:
                if (wsi->trunc_len) {
                        lws_callback_on_writable(wsi);
                        return;
                }
                lwsl_info("wsi %p completed LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE\n", wsi);
                goto just_kill_connection;
        default:
                if (wsi->trunc_len) {
                        lwsl_info("wsi %p entering LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE\n", wsi);
                        wsi->state = LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE;
                        lws_set_timeout(wsi, PENDING_FLUSH_STORED_SEND_BEFORE_CLOSE, 5);
                        return;
                }
                break;
        }

        if (wsi->mode == LWSCM_WSCL_WAITING_CONNECT ||
            wsi->mode == LWSCM_WSCL_ISSUE_HANDSHAKE)
                goto just_kill_connection;

        if (wsi->mode == LWSCM_HTTP_SERVING)
                context->protocols[0].callback(wsi, LWS_CALLBACK_CLOSED_HTTP,
                                               wsi->user_space, NULL, 0);

        /*
         * are his extensions okay with him closing?  Eg he might be a mux
         * parent and just his ch1 aspect is closing?
         */

        if (lws_ext_cb_active(wsi,
                      LWS_EXT_CB_CHECK_OK_TO_REALLY_CLOSE, NULL, 0) > 0) {
                lwsl_ext("extension vetoed close\n");
                return;
        }

        /*
         * flush any tx pending from extensions, since we may send close packet
         * if there are problems with send, just nuke the connection
         */

        do {
                ret = 0;
                eff_buf.token = NULL;
                eff_buf.token_len = 0;

                /* show every extension the new incoming data */

                m = lws_ext_cb_active(wsi,
                          LWS_EXT_CB_FLUSH_PENDING_TX, &eff_buf, 0);
                if (m < 0) {
                        lwsl_ext("Extension reports fatal error\n");
                        goto just_kill_connection;
                }
                if (m)
                        /*
                         * at least one extension told us he has more
                         * to spill, so we will go around again after
                         */
                        ret = 1;

                /* assuming they left us something to send, send it */

                if (eff_buf.token_len)
                        if (lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
                                          eff_buf.token_len) !=
                            eff_buf.token_len) {
                                lwsl_debug("close: ext spill failed\n");
                                goto just_kill_connection;
                        }
        } while (ret);

        /*
         * signal we are closing, lws_write will
         * add any necessary version-specific stuff.  If the write fails,
         * no worries we are closing anyway.  If we didn't initiate this
         * close, then our state has been changed to
         * LWSS_RETURNED_CLOSE_ALREADY and we will skip this.
         *
         * Likewise if it's a second call to close this connection after we
         * sent the close indication to the peer already, we are in state
         * LWSS_AWAITING_CLOSE_ACK and will skip doing this a second time.
         */

        if (wsi->state_pre_close == LWSS_ESTABLISHED &&
            (wsi->u.ws.close_in_ping_buffer_len || /* already a reason */
             (reason != LWS_CLOSE_STATUS_NOSTATUS &&
             (reason != LWS_CLOSE_STATUS_NOSTATUS_CONTEXT_DESTROY)))) {
                lwsl_debug("sending close indication...\n");

                /* if no prepared close reason, use 1000 and no aux data */
                if (!wsi->u.ws.close_in_ping_buffer_len) {
                        wsi->u.ws.close_in_ping_buffer_len = 2;
                        wsi->u.ws.ping_payload_buf[LWS_PRE] =
                                (reason >> 16) & 0xff;
                        wsi->u.ws.ping_payload_buf[LWS_PRE + 1] =
                                reason & 0xff;
                }

                n = lws_write(wsi, &wsi->u.ws.ping_payload_buf[LWS_PRE],
                              wsi->u.ws.close_in_ping_buffer_len,
                              LWS_WRITE_CLOSE);
                if (n >= 0) {
                        /*
                         * we have sent a nice protocol level indication we
                         * now wish to close, we should not send anything more
                         */
                        wsi->state = LWSS_AWAITING_CLOSE_ACK;

                        /*
                         * ...and we should wait for a reply for a bit
                         * out of politeness
                         */
                        lws_set_timeout(wsi, PENDING_TIMEOUT_CLOSE_ACK, 1);
                        lwsl_debug("sent close indication, awaiting ack\n");

                        return;
                }

                lwsl_info("close: sending close packet failed, hanging up\n");

                /* else, the send failed and we should just hang up */
        }

just_kill_connection:

#if LWS_POSIX
        /*
         * Testing with ab shows that we have to stage the socket close when
         * the system is under stress... shutdown any further TX, change the
         * state to one that won't emit anything more, and wait with a timeout
         * for the POLLIN to show a zero-size rx before coming back and doing
         * the actual close.
         */
        if (wsi->state != LWSS_SHUTDOWN) {
                lwsl_info("%s: shutting down connection: %p\n", __func__, wsi);
                n = shutdown(wsi->sock, SHUT_WR);
                if (n)
                        lwsl_debug("closing: shutdown ret %d\n", LWS_ERRNO);
                wsi->state = LWSS_SHUTDOWN;
                lws_change_pollfd(wsi, LWS_POLLOUT, LWS_POLLIN);
                lws_set_timeout(wsi, PENDING_TIMEOUT_SHUTDOWN_FLUSH,
                                AWAITING_TIMEOUT);
                return;
        }
#endif

        lwsl_info("%s: real just_kill_connection: %p\n", __func__, wsi);

        /*
         * we won't be servicing or receiving anything further from this guy
         * delete socket from the internal poll list if still present
         */
        lws_ssl_remove_wsi_from_buffered_list(wsi);
        lws_remove_from_timeout_list(wsi);

        /* checking return redundant since we anyway close */
        remove_wsi_socket_from_fds(wsi);

        wsi->state = LWSS_DEAD_SOCKET;

        lws_free_set_NULL(wsi->rxflow_buffer);

        if (wsi->state_pre_close == LWSS_ESTABLISHED ||
            wsi->mode == LWSCM_WS_SERVING ||
            wsi->mode == LWSCM_WS_CLIENT) {

                if (wsi->u.ws.rx_draining_ext) {
                        struct lws **w = &pt->rx_draining_ext_list;

                        wsi->u.ws.rx_draining_ext = 0;
                        /* remove us from context draining ext list */
                        while (*w) {
                                if (*w == wsi) {
                                        *w = wsi->u.ws.rx_draining_ext_list;
                                        break;
                                }
                                w = &((*w)->u.ws.rx_draining_ext_list);
                        }
                        wsi->u.ws.rx_draining_ext_list = NULL;
                }

                if (wsi->u.ws.tx_draining_ext) {
                        struct lws **w = &pt->tx_draining_ext_list;

                        wsi->u.ws.tx_draining_ext = 0;
                        /* remove us from context draining ext list */
                        while (*w) {
                                if (*w == wsi) {
                                        *w = wsi->u.ws.tx_draining_ext_list;
                                        break;
                                }
                                w = &((*w)->u.ws.tx_draining_ext_list);
                        }
                        wsi->u.ws.tx_draining_ext_list = NULL;
                }
                lws_free_set_NULL(wsi->u.ws.rx_ubuf);

                if (wsi->trunc_alloc)
                        /* not going to be completed... nuke it */
                        lws_free_set_NULL(wsi->trunc_alloc);

                wsi->u.ws.ping_payload_len = 0;
                wsi->u.ws.ping_pending_flag = 0;
        }

        /* tell the user it's all over for this guy */

        if (wsi->protocol && wsi->protocol->callback &&
            ((wsi->state_pre_close == LWSS_ESTABLISHED) ||
            (wsi->state_pre_close == LWSS_RETURNED_CLOSE_ALREADY) ||
            (wsi->state_pre_close == LWSS_AWAITING_CLOSE_ACK) ||
            (wsi->state_pre_close == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE))) {
                lwsl_debug("calling back CLOSED\n");
                wsi->protocol->callback(wsi, LWS_CALLBACK_CLOSED,
                                        wsi->user_space, NULL, 0);
        } else if (wsi->mode == LWSCM_HTTP_SERVING_ACCEPTED) {
                lwsl_debug("calling back CLOSED_HTTP\n");
                context->protocols[0].callback(wsi, LWS_CALLBACK_CLOSED_HTTP,
                                               wsi->user_space, NULL, 0 );
        } else if (wsi->mode == LWSCM_WSCL_WAITING_SERVER_REPLY ||
                   wsi->mode == LWSCM_WSCL_WAITING_CONNECT) {
                lwsl_debug("Connection closed before server reply\n");
                context->protocols[0].callback(wsi,
                                        LWS_CALLBACK_CLIENT_CONNECTION_ERROR,
                                        wsi->user_space, NULL, 0);
        } else
                lwsl_debug("not calling back closed mode=%d state=%d\n",
                           wsi->mode, wsi->state_pre_close);

        /* deallocate any active extension contexts */

        if (lws_ext_cb_active(wsi, LWS_EXT_CB_DESTROY, NULL, 0) < 0)
                lwsl_warn("extension destruction failed\n");
        /*
         * inform all extensions in case they tracked this guy out of band
         * even though not active on him specifically
         */
        if (lws_ext_cb_all_exts(context, wsi,
                       LWS_EXT_CB_DESTROY_ANY_WSI_CLOSING, NULL, 0) < 0)
                lwsl_warn("ext destroy wsi failed\n");

        wsi->socket_is_permanently_unusable = 1;

        if (!lws_ssl_close(wsi) && lws_socket_is_valid(wsi->sock)) {
#if LWS_POSIX
                n = compatible_close(wsi->sock);
                if (n)
                        lwsl_debug("closing: close ret %d\n", LWS_ERRNO);

#else
                compatible_close(wsi->sock);
#endif
                wsi->sock = LWS_SOCK_INVALID;
        }

        /* outermost destroy notification for wsi (user_space still intact) */
        context->protocols[0].callback(wsi, LWS_CALLBACK_WSI_DESTROY,
                                       wsi->user_space, NULL, 0);

        lws_free_wsi(wsi);
}

#if LWS_POSIX
LWS_VISIBLE int
interface_to_sa(struct lws_context *context, const char *ifname, struct sockaddr_in *addr, size_t addrlen)
{
        int ipv6 = 0;
#ifdef LWS_USE_IPV6
        ipv6 = LWS_IPV6_ENABLED(context);
#endif
        (void)context;

        return lws_interface_to_sa(ipv6, ifname, addr, addrlen);
}
#endif

LWS_VISIBLE int
lws_get_addresses(struct lws_context *context, void *ads, char *name,
                  int name_len, char *rip, int rip_len)
{
#if LWS_POSIX
        struct addrinfo ai, *res;
        struct sockaddr_in addr4;

        if (rip)
                rip[0] = '\0';
        name[0] = '\0';
        addr4.sin_family = AF_UNSPEC;

#ifdef LWS_USE_IPV6
        if (LWS_IPV6_ENABLED(context)) {
                if (!lws_plat_inet_ntop(AF_INET6, &((struct sockaddr_in6 *)ads)->sin6_addr, rip, rip_len)) {
                        lwsl_err("inet_ntop", strerror(LWS_ERRNO));
                        return -1;
                }

                // Strip off the IPv4 to IPv6 header if one exists
                if (strncmp(rip, "::ffff:", 7) == 0)
                        memmove(rip, rip + 7, strlen(rip) - 6);

                getnameinfo((struct sockaddr *)ads,
                                sizeof(struct sockaddr_in6), name,
                                                        name_len, NULL, 0, 0);

                return 0;
        } else
#endif
        {
                struct addrinfo *result;

                memset(&ai, 0, sizeof ai);
                ai.ai_family = PF_UNSPEC;
                ai.ai_socktype = SOCK_STREAM;
                ai.ai_flags = AI_CANONNAME;

                if (getnameinfo((struct sockaddr *)ads,
                                sizeof(struct sockaddr_in),
                                name, name_len, NULL, 0, 0))
                        return -1;

                if (!rip)
                        return 0;

                if (getaddrinfo(name, NULL, &ai, &result))
                        return -1;

                res = result;
                while (addr4.sin_family == AF_UNSPEC && res) {
                        switch (res->ai_family) {
                        case AF_INET:
                                addr4.sin_addr = ((struct sockaddr_in *)res->ai_addr)->sin_addr;
                                addr4.sin_family = AF_INET;
                                break;
                        }

                        res = res->ai_next;
                }
                freeaddrinfo(result);
        }

        if (addr4.sin_family == AF_UNSPEC)
                return -1;

        if (lws_plat_inet_ntop(AF_INET, &addr4.sin_addr, rip, rip_len) == NULL)
                return -1;

        return 0;
#else
        (void)context;
        (void)ads;
        (void)name;
        (void)name_len;
        (void)rip;
        (void)rip_len;

        return -1;
#endif
}

/**
 * lws_get_peer_addresses() - Get client address information
 * @wsi:        Local struct lws associated with
 * @fd:         Connection socket descriptor
 * @name:       Buffer to take client address name
 * @name_len:   Length of client address name buffer
 * @rip:        Buffer to take client address IP dotted quad
 * @rip_len:    Length of client address IP buffer
 *
 *      This function fills in @name and @rip with the name and IP of
 *      the client connected with socket descriptor @fd.  Names may be
 *      truncated if there is not enough room.  If either cannot be
 *      determined, they will be returned as valid zero-length strings.
 */

LWS_VISIBLE void
lws_get_peer_addresses(struct lws *wsi, lws_sockfd_type fd, char *name,
                       int name_len, char *rip, int rip_len)
{
#if LWS_POSIX
        socklen_t len;
#ifdef LWS_USE_IPV6
        struct sockaddr_in6 sin6;
#endif
        struct sockaddr_in sin4;
        struct lws_context *context = wsi->context;
        int ret = -1;
        void *p;

        rip[0] = '\0';
        name[0] = '\0';

        lws_latency_pre(context, wsi);

#ifdef LWS_USE_IPV6
        if (LWS_IPV6_ENABLED(context)) {
                len = sizeof(sin6);
                p = &sin6;
        } else
#endif
        {
                len = sizeof(sin4);
                p = &sin4;
        }

        if (getpeername(fd, p, &len) < 0) {
                lwsl_warn("getpeername: %s\n", strerror(LWS_ERRNO));
                goto bail;
        }

        ret = lws_get_addresses(context, p, name, name_len, rip, rip_len);

bail:
        lws_latency(context, wsi, "lws_get_peer_addresses", ret, 1);
#else
        (void)wsi;
        (void)fd;
        (void)name;
        (void)name_len;
        (void)rip;
        (void)rip_len;
#endif
}

/**
 * lws_context_user() - get the user data associated with the context
 * @context: Websocket context
 *
 *      This returns the optional user allocation that can be attached to
 *      the context the sockets live in at context_create time.  It's a way
 *      to let all sockets serviced in the same context share data without
 *      using globals statics in the user code.
 */
LWS_EXTERN void *
lws_context_user(struct lws_context *context)
{
        return context->user_space;
}


/**
 * lws_callback_all_protocol() - Callback all connections using
 *                              the given protocol with the given reason
 *
 * @protocol:   Protocol whose connections will get callbacks
 * @reason:     Callback reason index
 */

LWS_VISIBLE int
lws_callback_all_protocol(struct lws_context *context,
                          const struct lws_protocols *protocol, int reason)
{
        struct lws_context_per_thread *pt = &context->pt[0];
        struct lws *wsi;
        unsigned int n, m = context->count_threads;

        while (m--) {
                for (n = 0; n < pt->fds_count; n++) {
                        wsi = wsi_from_fd(context, pt->fds[n].fd);
                        if (!wsi)
                                continue;
                        if (wsi->protocol == protocol)
                                protocol->callback(wsi, reason, wsi->user_space, NULL, 0);
                }
                pt++;
        }

        return 0;
}

#if LWS_POSIX

/**
 * lws_get_socket_fd() - returns the socket file descriptor
 *
 * You will not need this unless you are doing something special
 *
 * @wsi:        Websocket connection instance
 */

LWS_VISIBLE int
lws_get_socket_fd(struct lws *wsi)
{
        return wsi->sock;
}

#endif

#ifdef LWS_LATENCY
void
lws_latency(struct lws_context *context, struct lws *wsi, const char *action,
            int ret, int completed)
{
        unsigned long long u;
        char buf[256];

        u = time_in_microseconds();

        if (!action) {
                wsi->latency_start = u;
                if (!wsi->action_start)
                        wsi->action_start = u;
                return;
        }
        if (completed) {
                if (wsi->action_start == wsi->latency_start)
                        sprintf(buf,
                          "Completion first try lat %lluus: %p: ret %d: %s\n",
                                        u - wsi->latency_start,
                                                      (void *)wsi, ret, action);
                else
                        sprintf(buf,
                          "Completion %lluus: lat %lluus: %p: ret %d: %s\n",
                                u - wsi->action_start,
                                        u - wsi->latency_start,
                                                      (void *)wsi, ret, action);
                wsi->action_start = 0;
        } else
                sprintf(buf, "lat %lluus: %p: ret %d: %s\n",
                              u - wsi->latency_start, (void *)wsi, ret, action);

        if (u - wsi->latency_start > context->worst_latency) {
                context->worst_latency = u - wsi->latency_start;
                strcpy(context->worst_latency_info, buf);
        }
        lwsl_latency("%s", buf);
}
#endif



/**
 * lws_rx_flow_control() - Enable and disable socket servicing for
 *                              received packets.
 *
 * If the output side of a server process becomes choked, this allows flow
 * control for the input side.
 *
 * @wsi:        Websocket connection instance to get callback for
 * @enable:     0 = disable read servicing for this connection, 1 = enable
 */

LWS_VISIBLE int
lws_rx_flow_control(struct lws *wsi, int enable)
{
        if (enable == (wsi->rxflow_change_to & LWS_RXFLOW_ALLOW))
                return 0;

        lwsl_info("%s: (0x%p, %d)\n", __func__, wsi, enable);
        wsi->rxflow_change_to = LWS_RXFLOW_PENDING_CHANGE | !!enable;

        return 0;
}

/**
 * lws_rx_flow_allow_all_protocol() - Allow all connections with this protocol to receive
 *
 * When the user server code realizes it can accept more input, it can
 * call this to have the RX flow restriction removed from all connections using
 * the given protocol.
 *
 * @protocol:   all connections using this protocol will be allowed to receive
 */

LWS_VISIBLE void
lws_rx_flow_allow_all_protocol(const struct lws_context *context,
                               const struct lws_protocols *protocol)
{
        const struct lws_context_per_thread *pt = &context->pt[0];
        struct lws *wsi;
        unsigned int n, m = context->count_threads;

        while (m--) {
                for (n = 0; n < pt->fds_count; n++) {
                        wsi = wsi_from_fd(context, pt->fds[n].fd);
                        if (!wsi)
                                continue;
                        if (wsi->protocol == protocol)
                                lws_rx_flow_control(wsi, LWS_RXFLOW_ALLOW);
                }
                pt++;
        }
}


/**
 * lws_canonical_hostname() - returns this host's hostname
 *
 * This is typically used by client code to fill in the host parameter
 * when making a client connection.  You can only call it after the context
 * has been created.
 *
 * @context:    Websocket context
 */
LWS_VISIBLE extern const char *
lws_canonical_hostname(struct lws_context *context)
{
        return (const char *)context->canonical_hostname;
}

int user_callback_handle_rxflow(lws_callback_function callback_function,
                                struct lws *wsi,
                                enum lws_callback_reasons reason, void *user,
                                void *in, size_t len)
{
        int n;

        n = callback_function(wsi, reason, user, in, len);
        if (!n)
                n = _lws_rx_flow_control(wsi);

        return n;
}


/**
 * lws_set_proxy() - Setups proxy to lws_context.
 * @context:    pointer to struct lws_context you want set proxy to
 * @proxy: pointer to c string containing proxy in format address:port
 *
 * Returns 0 if proxy string was parsed and proxy was setup.
 * Returns -1 if @proxy is NULL or has incorrect format.
 *
 * This is only required if your OS does not provide the http_proxy
 * environment variable (eg, OSX)
 *
 *   IMPORTANT! You should call this function right after creation of the
 *   lws_context and before call to connect. If you call this
 *   function after connect behavior is undefined.
 *   This function will override proxy settings made on lws_context
 *   creation with genenv() call.
 */

LWS_VISIBLE int
lws_set_proxy(struct lws_context *context, const char *proxy)
{
        char *p;
        char authstring[96];

        if (!proxy)
                return -1;

        p = strchr(proxy, '@');
        if (p) { /* auth is around */

                if ((unsigned int)(p - proxy) > sizeof(authstring) - 1)
                        goto auth_too_long;

                strncpy(authstring, proxy, p - proxy);
                // null termination not needed on input
                if (lws_b64_encode_string(authstring, (p - proxy),
                    context->proxy_basic_auth_token,
                    sizeof context->proxy_basic_auth_token) < 0)
                        goto auth_too_long;

                lwsl_notice(" Proxy auth in use\n");

                proxy = p + 1;
        } else
                context->proxy_basic_auth_token[0] = '\0';

        strncpy(context->http_proxy_address, proxy,
                                sizeof(context->http_proxy_address) - 1);
        context->http_proxy_address[
                                sizeof(context->http_proxy_address) - 1] = '\0';

        p = strchr(context->http_proxy_address, ':');
        if (!p && !context->http_proxy_port) {
                lwsl_err("http_proxy needs to be ads:port\n");

                return -1;
        } else {
                if (p) {
                        *p = '\0';
                        context->http_proxy_port = atoi(p + 1);
                }
        }

        lwsl_notice(" Proxy %s:%u\n", context->http_proxy_address,
                                                context->http_proxy_port);

        return 0;

auth_too_long:
        lwsl_err("proxy auth too long\n");

        return -1;
}

/**
 * lws_get_protocol() - Returns a protocol pointer from a websocket
 *                                connection.
 * @wsi:        pointer to struct websocket you want to know the protocol of
 *
 *
 *      Some apis can act on all live connections of a given protocol,
 *      this is how you can get a pointer to the active protocol if needed.
 */

LWS_VISIBLE const struct lws_protocols *
lws_get_protocol(struct lws *wsi)
{
        return wsi->protocol;
}

LWS_VISIBLE int
lws_is_final_fragment(struct lws *wsi)
{
        lwsl_info("%s: final %d, rx pk length %d, draining %d", __func__,
                        wsi->u.ws.final, wsi->u.ws.rx_packet_length, wsi->u.ws.rx_draining_ext);
        return wsi->u.ws.final && !wsi->u.ws.rx_packet_length && !wsi->u.ws.rx_draining_ext;
}

LWS_VISIBLE unsigned char
lws_get_reserved_bits(struct lws *wsi)
{
        return wsi->u.ws.rsv;
}

int
lws_ensure_user_space(struct lws *wsi)
{
        lwsl_info("%s: %p protocol %p\n", __func__, wsi, wsi->protocol);
        if (!wsi->protocol)
                return 1;

        /* allocate the per-connection user memory (if any) */

        if (wsi->protocol->per_session_data_size && !wsi->user_space) {
                wsi->user_space = lws_zalloc(wsi->protocol->per_session_data_size);
                if (wsi->user_space  == NULL) {
                        lwsl_err("Out of memory for conn user space\n");
                        return 1;
                }
        } else
                lwsl_info("%s: %p protocol pss %u, user_space=%d\n",
                          __func__, wsi, wsi->protocol->per_session_data_size,
                          wsi->user_space);
        return 0;
}

LWS_VISIBLE void lwsl_emit_stderr(int level, const char *line)
{
        unsigned long long now;
        char buf[300];
        int n;

        buf[0] = '\0';
        for (n = 0; n < LLL_COUNT; n++) {
                if (level != (1 << n))
                        continue;
                now = time_in_microseconds() / 100;
                sprintf(buf, "[%llu:%04d] %s: ",
                        (unsigned long long) now / 10000,
                        (int)(now % 10000), log_level_names[n]);
                break;
        }

        fprintf(stderr, "%s%s", buf, line);
}

LWS_VISIBLE void _lws_logv(int filter, const char *format, va_list vl)
{
        char buf[256];

        if (!(log_level & filter))
                return;

        vsnprintf(buf, sizeof(buf), format, vl);
        buf[sizeof(buf) - 1] = '\0';

        lwsl_emit(filter, buf);
}

LWS_VISIBLE void _lws_log(int filter, const char *format, ...)
{
        va_list ap;

        va_start(ap, format);
        _lws_logv(filter, format, ap);
        va_end(ap);
}

/**
 * lws_set_log_level() - Set the logging bitfield
 * @level:      OR together the LLL_ debug contexts you want output from
 * @log_emit_function:  NULL to leave it as it is, or a user-supplied
 *                      function to perform log string emission instead of
 *                      the default stderr one.
 *
 *      log level defaults to "err", "warn" and "notice" contexts enabled and
 *      emission on stderr.
 */

LWS_VISIBLE void lws_set_log_level(int level,
                                   void (*func)(int level, const char *line))
{
        log_level = level;
        if (func)
                lwsl_emit = func;
}

/**
 * lws_use_ssl() - Find out if connection is using SSL
 * @wsi:        websocket connection to check
 *
 *      Returns 0 if the connection is not using SSL, 1 if using SSL and
 *      using verified cert, and 2 if using SSL but the cert was not
 *      checked (appears for client wsi told to skip check on connection)
 */
LWS_VISIBLE int
lws_is_ssl(struct lws *wsi)
{
#ifdef LWS_OPENSSL_SUPPORT
        return wsi->use_ssl;
#else
        (void)wsi;
        return 0;
#endif
}

/**
 * lws_partial_buffered() - find out if lws buffered the last write
 * @wsi:        websocket connection to check
 *
 * Returns 1 if you cannot use lws_write because the last
 * write on this connection is still buffered, and can't be cleared without
 * returning to the service loop and waiting for the connection to be
 * writeable again.
 *
 * If you will try to do >1 lws_write call inside a single
 * WRITEABLE callback, you must check this after every write and bail if
 * set, ask for a new writeable callback and continue writing from there.
 *
 * This is never set at the start of a writeable callback, but any write
 * may set it.
 */

LWS_VISIBLE int
lws_partial_buffered(struct lws *wsi)
{
        return !!wsi->trunc_len;
}

void lws_set_protocol_write_pending(struct lws *wsi,
                                    enum lws_pending_protocol_send pend)
{
        lwsl_info("setting pps %d\n", pend);

        if (wsi->pps)
                lwsl_err("pps overwrite\n");
        wsi->pps = pend;
        lws_rx_flow_control(wsi, 0);
        lws_callback_on_writable(wsi);
}

LWS_VISIBLE size_t
lws_get_peer_write_allowance(struct lws *wsi)
{
#ifdef LWS_USE_HTTP2
        /* only if we are using HTTP2 on this connection */
        if (wsi->mode != LWSCM_HTTP2_SERVING)
                return -1;
        /* user is only interested in how much he can send, or that he can't  */
        if (wsi->u.http2.tx_credit <= 0)
                return 0;

        return wsi->u.http2.tx_credit;
#else
        (void)wsi;
        return -1;
#endif
}

LWS_VISIBLE void
lws_union_transition(struct lws *wsi, enum connection_mode mode)
{
        lwsl_debug("%s: %p: mode %d\n", __func__, wsi, mode);
        memset(&wsi->u, 0, sizeof(wsi->u));
        wsi->mode = mode;
}

LWS_VISIBLE struct lws_plat_file_ops *
lws_get_fops(struct lws_context *context)
{
        return &context->fops;
}

LWS_VISIBLE LWS_EXTERN struct lws_context *
lws_get_context(const struct lws *wsi)
{
        return wsi->context;
}

LWS_VISIBLE LWS_EXTERN int
lws_get_count_threads(struct lws_context *context)
{
        return context->count_threads;
}

LWS_VISIBLE LWS_EXTERN void *
lws_wsi_user(struct lws *wsi)
{
        return wsi->user_space;
}

LWS_VISIBLE LWS_EXTERN void
lws_close_reason(struct lws *wsi, enum lws_close_status status,
                 unsigned char *buf, size_t len)
{
        unsigned char *p, *start;
        int budget = sizeof(wsi->u.ws.ping_payload_buf) - LWS_PRE;

        assert(wsi->mode == LWSCM_WS_SERVING || wsi->mode == LWSCM_WS_CLIENT);

        start = p = &wsi->u.ws.ping_payload_buf[LWS_PRE];

        *p++ = (((int)status) >> 8) & 0xff;
        *p++ = ((int)status) & 0xff;

        if (buf)
                while (len-- && p < start + budget)
                        *p++ = *buf++;

        wsi->u.ws.close_in_ping_buffer_len = p - start;
}

LWS_EXTERN int
_lws_rx_flow_control(struct lws *wsi)
{
        /* there is no pending change */
        if (!(wsi->rxflow_change_to & LWS_RXFLOW_PENDING_CHANGE)) {
                lwsl_debug("%s: no pending change\n", __func__);
                return 0;
        }

        /* stuff is still buffered, not ready to really accept new input */
        if (wsi->rxflow_buffer) {
                /* get ourselves called back to deal with stashed buffer */
                lws_callback_on_writable(wsi);
                return 0;
        }

        /* pending is cleared, we can change rxflow state */

        wsi->rxflow_change_to &= ~LWS_RXFLOW_PENDING_CHANGE;

        lwsl_info("rxflow: wsi %p change_to %d\n", wsi,
                              wsi->rxflow_change_to & LWS_RXFLOW_ALLOW);

        /* adjust the pollfd for this wsi */

        if (wsi->rxflow_change_to & LWS_RXFLOW_ALLOW) {
                if (lws_change_pollfd(wsi, 0, LWS_POLLIN)) {
                        lwsl_info("%s: fail\n", __func__);
                        return -1;
                }
        } else
                if (lws_change_pollfd(wsi, LWS_POLLIN, 0))
                        return -1;

        return 0;
}

LWS_EXTERN int
lws_check_utf8(unsigned char *state, unsigned char *buf, size_t len)
{
        static const unsigned char e0f4[] = {
                0xa0 | ((2 - 1) << 2) | 1, /* e0 */
                0x80 | ((4 - 1) << 2) | 1, /* e1 */
                0x80 | ((4 - 1) << 2) | 1, /* e2 */
                0x80 | ((4 - 1) << 2) | 1, /* e3 */
                0x80 | ((4 - 1) << 2) | 1, /* e4 */
                0x80 | ((4 - 1) << 2) | 1, /* e5 */
                0x80 | ((4 - 1) << 2) | 1, /* e6 */
                0x80 | ((4 - 1) << 2) | 1, /* e7 */
                0x80 | ((4 - 1) << 2) | 1, /* e8 */
                0x80 | ((4 - 1) << 2) | 1, /* e9 */
                0x80 | ((4 - 1) << 2) | 1, /* ea */
                0x80 | ((4 - 1) << 2) | 1, /* eb */
                0x80 | ((4 - 1) << 2) | 1, /* ec */
                0x80 | ((2 - 1) << 2) | 1, /* ed */
                0x80 | ((4 - 1) << 2) | 1, /* ee */
                0x80 | ((4 - 1) << 2) | 1, /* ef */
                0x90 | ((3 - 1) << 2) | 2, /* f0 */
                0x80 | ((4 - 1) << 2) | 2, /* f1 */
                0x80 | ((4 - 1) << 2) | 2, /* f2 */
                0x80 | ((4 - 1) << 2) | 2, /* f3 */
                0x80 | ((1 - 1) << 2) | 2, /* f4 */

                0,                         /* s0 */
                0x80 | ((4 - 1) << 2) | 0, /* s2 */
                0x80 | ((4 - 1) << 2) | 1, /* s3 */
        };
        unsigned char s = *state;

        while (len--) {
                unsigned char c = *buf++;

                if (!s) {
                        if (c >= 0x80) {
                                if (c < 0xc2 || c > 0xf4)
                                        return 1;
                                if (c < 0xe0)
                                        s = 0x80 | ((4 - 1) << 2);
                                else
                                        s = e0f4[c - 0xe0];
                        }
                } else {
                        if (c < (s & 0xf0) ||
                            c >= (s & 0xf0) + 0x10 + ((s << 2) & 0x30))
                                return 1;
                        s = e0f4[21 + (s & 3)];
                }
        }

        *state = s;

        return 0;
}

/**
 * lws_parse_uri:       cut up https:/xxx:yyy/zzz into pieces
 *                      Notice it does so by dropping '\0' into input string
 *
 * @p:                  incoming uri string.. will get written to
 * @prot:               result pointer for protocol part (https://)
 * @ads:                result pointer for address part
 * @port:               result pointer for port part
 * @path:               result pointer for path part
 */

LWS_VISIBLE LWS_EXTERN int
lws_parse_uri(char *p, const char **prot, const char **ads, int *port,
              const char **path)
{
        const char *end;
        static const char *slash = "/";

        /* cut up the location into address, port and path */
        *prot = p;
        while (*p && (*p != ':' || p[1] != '/' || p[2] != '/'))
                p++;
        if (!*p) {
                end = p;
                p = (char *)*prot;
                *prot = end;
        } else {
                *p = '\0';
                p += 3;
        }
        *ads = p;
        if (!strcmp(*prot, "http") || !strcmp(*prot, "ws"))
                *port = 80;
        else if (!strcmp(*prot, "https") || !strcmp(*prot, "wss"))
                *port = 443;

        while (*p && *p != ':' && *p != '/')
                p++;
        if (*p == ':') {
                *p++ = '\0';
                *port = atoi(p);
                while (*p && *p != '/')
                        p++;
        }
        *path = slash;
        if (*p) {
                *p++ = '\0';
                if (*p)
                        *path = p;
        }

        return 0;
}

#ifdef LWS_NO_EXTENSIONS

/* we need to provide dummy callbacks for internal exts
 * so user code runs when faced with a lib compiled with
 * extensions disabled.
 */

int
lws_extension_callback_pm_deflate(struct lws_context *context,
                                  const struct lws_extension *ext,
                                  struct lws *wsi,
                                  enum lws_extension_callback_reasons reason,
                                  void *user, void *in, size_t len)
{
        (void)context;
        (void)ext;
        (void)wsi;
        (void)reason;
        (void)user;
        (void)in;
        (void)len;

        return 0;
}
#endif