/*
 * mod_wstunnel originally based off https://github.com/nori0428/mod_websocket
 * Portions of this module Copyright(c) 2017, Glenn Strauss, All rights reserved
 * Portions of this module Copyright(c) 2010, Norio Kobota, All rights reserved.
 */

/*
 * Copyright(c) 2010, Norio Kobota, All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name of the 'incremental' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

/* NOTES:
 *
 * mod_wstunnel has been largely rewritten from Norio Kobota mod_websocket.
 *
 * highlighted differences from Norio Kobota mod_websocket
 * - re-coded to use lighttpd 1.4.46 buffer, chunkqueue, and gw_backend APIs
 * - websocket.server "ext" value is no longer regex;
 *   operates similar to mod_proxy for either path prefix or extension match
 * - validation of "origins" value is no longer regex; operates as suffix match
 *   (admin could use lighttpd.conf regex on "Origin" or "Sec-WebSocket-Origin"
 *    and reject non-matches with mod_access if such regex validation required)
 * - websocket transparent proxy mode removed; functionality is now in mod_proxy
 *   Backend server which responds to Connection: upgrade and Upgrade: websocket
 *   should check "Origin" and/or "Sec-WebSocket-Origin".  lighttpd.conf could
 *   additionally be configured to check
 *     $REQUEST_HEADER["Sec-WebSocket-Origin"] !~ "..."
 *   with regex, and mod_access used to reject non-matches, if desired.
 * - connections to backend no longer block, but only first address returned
 *   by getaddrinfo() is used; lighttpd does not cycle through all addresses
 *   returned by DNS resolution.  Note: DNS resolution occurs once at startup.
 * - directives renamed from websocket.* to wstunnel.*
 * - directive websocket.ping_interval replaced with wstunnel.ping-interval
 *     (note the '_' changed to '-')
 * - directive websocket.timeout should be replaced with server.max-read-idle
 * - attribute "type" is an independent directive wstunnel.frame-type
 *     (default is "text" unless "binary" is specified)
 * - attribute "origins" is an independent directive wstunnel.origins
 * - attribute "proto" removed; mod_proxy can proxy to backend websocket server
 * - attribute "subproto" should be replaced with mod_setenv directive
 *     setenv.set-response-header = ( "Sec-WebSocket-Protocol" => "..." )
 *     if header is required
 *
 * not reviewed:
 * - websocket protocol compliance has not been reviewed
 *     e.g. when to send 1000 Normal Closure and when to send 1001 Going Away
 * - websocket protocol sanity checking has not been reviewed
 *
 * References:
 *   https://en.wikipedia.org/wiki/WebSocket
 *   https://tools.ietf.org/html/rfc6455
 *   https://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-00
 */
#include "first.h"

#include <sys/types.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include "gw_backend.h"

#include "base.h"
#include "array.h"
#include "buffer.h"
#include "chunk.h"
#include "fdevent.h"
#include "http_header.h"
#include "log.h"

#define MOD_WEBSOCKET_LOG_NONE  0
#define MOD_WEBSOCKET_LOG_ERR   1
#define MOD_WEBSOCKET_LOG_WARN  2
#define MOD_WEBSOCKET_LOG_INFO  3
#define MOD_WEBSOCKET_LOG_DEBUG 4

#define DEBUG_LOG_ERR(format, ...) \
  if (hctx->gw.conf.debug >= MOD_WEBSOCKET_LOG_ERR) { log_error(hctx->errh, __FILE__, __LINE__, (format), __VA_ARGS__); }

#define DEBUG_LOG_WARN(format, ...) \
  if (hctx->gw.conf.debug >= MOD_WEBSOCKET_LOG_WARN) { log_error(hctx->errh, __FILE__, __LINE__, (format), __VA_ARGS__); }

#define DEBUG_LOG_INFO(format, ...) \
  if (hctx->gw.conf.debug >= MOD_WEBSOCKET_LOG_INFO) { log_error(hctx->errh, __FILE__, __LINE__, (format), __VA_ARGS__); }

#define DEBUG_LOG_DEBUG(format, ...) \
  if (hctx->gw.conf.debug >= MOD_WEBSOCKET_LOG_DEBUG) { log_error(hctx->errh, __FILE__, __LINE__, (format), __VA_ARGS__); }

typedef struct {
    gw_plugin_config gw; /* start must match layout of gw_plugin_config */
    const array *origins;
    unsigned int frame_type;
    unsigned short int ping_interval;
} plugin_config;

typedef struct plugin_data {
    PLUGIN_DATA;
    pid_t srv_pid; /* must match layout of gw_plugin_data through conf member */
    plugin_config conf;
    plugin_config defaults;
} plugin_data;

typedef enum {
    MOD_WEBSOCKET_FRAME_STATE_INIT,

    /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */
    MOD_WEBSOCKET_FRAME_STATE_READ_LENGTH,
    MOD_WEBSOCKET_FRAME_STATE_READ_EX_LENGTH,
    MOD_WEBSOCKET_FRAME_STATE_READ_MASK,
    /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */

    MOD_WEBSOCKET_FRAME_STATE_READ_PAYLOAD
} mod_wstunnel_frame_state_t;

typedef enum {
    MOD_WEBSOCKET_FRAME_TYPE_TEXT,
    MOD_WEBSOCKET_FRAME_TYPE_BIN,
    MOD_WEBSOCKET_FRAME_TYPE_CLOSE,

    /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */
    MOD_WEBSOCKET_FRAME_TYPE_PING,
    MOD_WEBSOCKET_FRAME_TYPE_PONG
    /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */

} mod_wstunnel_frame_type_t;

typedef struct {
    uint64_t siz;

    /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */
    int siz_cnt;
    int mask_cnt;
    #define MOD_WEBSOCKET_MASK_CNT 4
    unsigned char mask[MOD_WEBSOCKET_MASK_CNT];
    /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */

} mod_wstunnel_frame_control_t;

typedef struct {
    mod_wstunnel_frame_state_t state;
    mod_wstunnel_frame_control_t ctl;
    mod_wstunnel_frame_type_t type, type_before, type_backend;
    buffer *payload;
} mod_wstunnel_frame_t;

typedef struct {
    gw_handler_ctx gw;
    mod_wstunnel_frame_t frame;

    int hybivers;
    unix_time64_t ping_ts;
    int subproto;

    log_error_st *errh; /*(for mod_wstunnel module-specific DEBUG_*() macros)*/
    plugin_config conf;
} handler_ctx;

/* prototypes */
static handler_t mod_wstunnel_handshake_create_response(handler_ctx *);
static int mod_wstunnel_frame_send(handler_ctx *, mod_wstunnel_frame_type_t, const char *, size_t);
static int mod_wstunnel_frame_recv(handler_ctx *);
#define _MOD_WEBSOCKET_SPEC_IETF_00_
#define _MOD_WEBSOCKET_SPEC_RFC_6455_

INIT_FUNC(mod_wstunnel_init) {
    return ck_calloc(1, sizeof(plugin_data));
}

static void mod_wstunnel_merge_config_cpv(plugin_config * const pconf, const config_plugin_value_t * const cpv) {
    switch (cpv->k_id) { /* index into static config_plugin_keys_t cpk[] */
      case 0: /* wstunnel.server */
        if (cpv->vtype == T_CONFIG_LOCAL) {
            gw_plugin_config * const gw = cpv->v.v;
            pconf->gw.exts      = gw->exts;
            pconf->gw.exts_auth = gw->exts_auth;
            pconf->gw.exts_resp = gw->exts_resp;
        }
        break;
      case 1: /* wstunnel.balance */
        /*if (cpv->vtype == T_CONFIG_LOCAL)*//*always true here for this param*/
            pconf->gw.balance = (int)cpv->v.u;
        break;
      case 2: /* wstunnel.debug */
        pconf->gw.debug = (int)cpv->v.u;
        break;
      case 3: /* wstunnel.map-extensions */
        pconf->gw.ext_mapping = cpv->v.a;
        break;
      case 4: /* wstunnel.frame-type */
        pconf->frame_type = cpv->v.u;
        break;
      case 5: /* wstunnel.origins */
        pconf->origins = cpv->v.a;
        break;
      case 6: /* wstunnel.ping-interval */
        pconf->ping_interval = cpv->v.shrt;
        break;
      default:/* should not happen */
        return;
    }
}

static void mod_wstunnel_merge_config(plugin_config * const pconf, const config_plugin_value_t *cpv) {
    do {
        mod_wstunnel_merge_config_cpv(pconf, cpv);
    } while ((++cpv)->k_id != -1);
}

static void mod_wstunnel_patch_config(request_st * const r, plugin_data * const p) {
    memcpy(&p->conf, &p->defaults, sizeof(plugin_config));
    for (int i = 1, used = p->nconfig; i < used; ++i) {
        if (config_check_cond(r, (uint32_t)p->cvlist[i].k_id))
            mod_wstunnel_merge_config(&p->conf, p->cvlist+p->cvlist[i].v.u2[0]);
    }
}

SETDEFAULTS_FUNC(mod_wstunnel_set_defaults) {
    static const config_plugin_keys_t cpk[] = {
      { CONST_STR_LEN("wstunnel.server"),
        T_CONFIG_ARRAY_KVARRAY,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ CONST_STR_LEN("wstunnel.balance"),
        T_CONFIG_STRING,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ CONST_STR_LEN("wstunnel.debug"),
        T_CONFIG_INT,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ CONST_STR_LEN("wstunnel.map-extensions"),
        T_CONFIG_ARRAY_KVSTRING,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ CONST_STR_LEN("wstunnel.frame-type"),
        T_CONFIG_STRING,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ CONST_STR_LEN("wstunnel.origins"),
        T_CONFIG_ARRAY_VLIST,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ CONST_STR_LEN("wstunnel.ping-interval"),
        T_CONFIG_SHORT,
        T_CONFIG_SCOPE_CONNECTION }
     ,{ NULL, 0,
        T_CONFIG_UNSET,
        T_CONFIG_SCOPE_UNSET }
    };

    plugin_data * const p = p_d;
    if (!config_plugin_values_init(srv, p, cpk, "mod_wstunnel"))
        return HANDLER_ERROR;

    /* process and validate config directives
     * (init i to 0 if global context; to 1 to skip empty global context) */
    for (int i = !p->cvlist[0].v.u2[1]; i < p->nconfig; ++i) {
        config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0];
        gw_plugin_config *gw = NULL;
        for (; -1 != cpv->k_id; ++cpv) {
            switch (cpv->k_id) {
              case 0: /* wstunnel.server */
                gw = ck_calloc(1, sizeof(gw_plugin_config));
                if (!gw_set_defaults_backend(srv, (gw_plugin_data *)p, cpv->v.a,
                                             gw, 0, cpk[cpv->k_id].k)) {
                    gw_plugin_config_free(gw);
                    return HANDLER_ERROR;
                }
                /* error if "mode" = "authorizer";
                 * wstunnel can not act as authorizer */
                /*(check after gw_set_defaults_backend())*/
                if (gw->exts_auth && gw->exts_auth->used) {
                    log_error(srv->errh, __FILE__, __LINE__,
                      "%s must not define any hosts with "
                      "attribute \"mode\" = \"authorizer\"", cpk[cpv->k_id].k);
                    gw_plugin_config_free(gw);
                    return HANDLER_ERROR;
                }
                cpv->v.v = gw;
                cpv->vtype = T_CONFIG_LOCAL;
                break;
              case 1: /* wstunnel.balance */
                cpv->v.u = (unsigned int)gw_get_defaults_balance(srv, cpv->v.b);
                break;
              case 2: /* wstunnel.debug */
              case 3: /* wstunnel.map-extensions */
                break;
              case 4: /* wstunnel.frame-type */
                /*(default frame-type to "text" unless "binary" is specified)*/
                cpv->v.u =
                  buffer_eq_icase_slen(cpv->v.b, CONST_STR_LEN("binary"));
                break;
              case 5: /* wstunnel.origins */
                for (uint32_t j = 0; j < cpv->v.a->used; ++j) {
                    buffer *origin = &((data_string *)cpv->v.a->data[j])->value;
                    if (buffer_is_blank(origin)) {
                        log_error(srv->errh, __FILE__, __LINE__,
                          "unexpected empty string in %s", cpk[cpv->k_id].k);
                        return HANDLER_ERROR;
                    }
                }
                break;
              case 6: /* wstunnel.ping-interval */
                break;
              default:/* should not happen */
                break;
            }
        }

        /* disable check-local for all exts (default enabled) */
        if (gw && gw->exts) { /*(check after gw_set_defaults_backend())*/
            gw_exts_clear_check_local(gw->exts);
        }
    }

    /* default is 0 */
    /*p->defaults.balance = (unsigned int)gw_get_defaults_balance(srv, NULL);*/
    p->defaults.ping_interval = 0; /* do not send ping */

    /* initialize p->defaults from global config context */
    if (p->nconfig > 0 && p->cvlist->v.u2[1]) {
        const config_plugin_value_t *cpv = p->cvlist + p->cvlist->v.u2[0];
        if (-1 != cpv->k_id)
            mod_wstunnel_merge_config(&p->defaults, cpv);
    }

    return HANDLER_GO_ON;
}

static handler_t wstunnel_create_env(gw_handler_ctx *gwhctx) {
    handler_ctx *hctx = (handler_ctx *)gwhctx;
    request_st * const r = hctx->gw.r;
    handler_t rc;
    if (0 == r->reqbody_length || r->http_version > HTTP_VERSION_1_1) {
        http_response_upgrade_read_body_unknown(r);
        chunkqueue_append_chunkqueue(&r->reqbody_queue, &r->read_queue);
    }
    rc = mod_wstunnel_handshake_create_response(hctx);
    if (rc != HANDLER_GO_ON) return rc;

    r->http_status = (r->http_version > HTTP_VERSION_1_1)
      ? 200  /* OK (response status for CONNECT) */
      : 101; /* Switching Protocols */
    r->resp_body_started = 1;

    hctx->ping_ts = log_monotonic_secs;
    gw_set_transparent(&hctx->gw);

    return HANDLER_GO_ON;
}

static handler_t wstunnel_stdin_append(gw_handler_ctx *gwhctx) {
    /* prepare websocket frames to backend */
    /* (caller should verify r->reqbody_queue) */
    /*assert(!chunkqueue_is_empty(&r->reqbody_queue));*/
    handler_ctx *hctx = (handler_ctx *)gwhctx;
    if (0 == mod_wstunnel_frame_recv(hctx))
        return HANDLER_GO_ON;
    else {
        /*(error)*/
        /* future: might differentiate client close request from client error,
         *         and then send 1000 or 1001 */
        request_st * const r = hctx->gw.r;
        DEBUG_LOG_INFO("disconnected from client (fd=%d)", r->con->fd);
        DEBUG_LOG_DEBUG("send close response to client (fd=%d)", r->con->fd);
        mod_wstunnel_frame_send(hctx, MOD_WEBSOCKET_FRAME_TYPE_CLOSE, CONST_STR_LEN("1000")); /* 1000 Normal Closure */
        gw_handle_request_reset(r, hctx->gw.plugin_data);
        return HANDLER_FINISHED;
    }
}

static handler_t wstunnel_recv_parse(request_st * const r, http_response_opts * const opts, buffer * const b, size_t n) {
    handler_ctx *hctx = (handler_ctx *)opts->pdata;
    DEBUG_LOG_DEBUG("recv data from backend (fd=%d), size=%zx", hctx->gw.fd, n);
    if (0 == n) return HANDLER_FINISHED;
    if (mod_wstunnel_frame_send(hctx,hctx->frame.type_backend,b->ptr,n) < 0) {
        DEBUG_LOG_ERR("%s", "fail to send data to client");
        return HANDLER_ERROR;
    }
    buffer_clear(b);
    UNUSED(r);
    return HANDLER_GO_ON;
}

static int wstunnel_is_allowed_origin(request_st * const r, handler_ctx * const hctx) {
    /* If allowed origins is set (and not empty list), fail closed if no match.
     * Note that origin provided in request header has not been normalized, so
     * change in case or other non-normal forms might not match allowed list */
    const array * const allowed_origins = hctx->conf.origins;
    const buffer *origin = NULL;
    size_t olen;

    if (NULL == allowed_origins || 0 == allowed_origins->used) {
        DEBUG_LOG_INFO("%s", "allowed origins not specified");
        return 1;
    }

    /* "Origin" header is preferred
     * ("Sec-WebSocket-Origin" is from older drafts of websocket spec) */
    origin = http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Origin"));
    if (NULL == origin) {
        origin =
          http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Sec-WebSocket-Origin"));
    }
    olen = origin ? buffer_clen(origin) : 0;
    if (0 == olen) {
        DEBUG_LOG_ERR("%s", "Origin header is invalid");
        r->http_status = 400; /* Bad Request */
        return 0;
    }

    for (size_t i = 0; i < allowed_origins->used; ++i) {
        buffer *b = &((data_string *)allowed_origins->data[i])->value;
        size_t blen = buffer_clen(b);
        if ((olen > blen ? origin->ptr[olen-blen-1] == '.' : olen == blen)
            && 0 == memcmp(origin->ptr+olen-blen, b->ptr, blen)) {
            DEBUG_LOG_INFO("%s matches allowed origin: %s",origin->ptr,b->ptr);
            return 1;
        }
    }
    DEBUG_LOG_INFO("%s does not match any allowed origins", origin->ptr);
    r->http_status = 403; /* Forbidden */
    return 0;
}

static int wstunnel_check_request(request_st * const r, handler_ctx * const hctx) {
    const buffer * const vers =
      http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Sec-WebSocket-Version"));
    const long hybivers = (NULL != vers)
      ? light_isdigit(*vers->ptr) ? strtol(vers->ptr, NULL, 10) : -1
      : 0;
    if (hybivers < 0 || hybivers > INT_MAX) {
        DEBUG_LOG_ERR("%s", "invalid Sec-WebSocket-Version");
        r->http_status = 400; /* Bad Request */
        return -1;
    }

    /*(redundant since HTTP/1.1 required in mod_wstunnel_check_extension())*/
    if (!r->http_host || buffer_is_blank(r->http_host)) {
        DEBUG_LOG_ERR("%s", "Host header does not exist");
        r->http_status = 400; /* Bad Request */
        return -1;
    }

    if (!wstunnel_is_allowed_origin(r, hctx)) {
        return -1;
    }

    return (int)hybivers;
}

static void wstunnel_backend_error(gw_handler_ctx *gwhctx) {
    handler_ctx *hctx = (handler_ctx *)gwhctx;
    if (hctx->gw.state == GW_STATE_WRITE || hctx->gw.state == GW_STATE_READ) {
        mod_wstunnel_frame_send(hctx, MOD_WEBSOCKET_FRAME_TYPE_CLOSE, CONST_STR_LEN("1001")); /* 1001 Going Away */
    }
}

static void wstunnel_handler_ctx_free(void *gwhctx) {
    handler_ctx *hctx = (handler_ctx *)gwhctx;
    chunk_buffer_release(hctx->frame.payload);
}

static handler_t wstunnel_handler_setup (request_st * const r, plugin_data * const p) {
    handler_ctx *hctx = r->plugin_ctx[p->id];
    int hybivers;
    hctx->errh = r->conf.errh;/*(for mod_wstunnel-specific DEBUG_* macros)*/
    hctx->conf = p->conf; /*(copies struct)*/
    hybivers = wstunnel_check_request(r, hctx);
    if (hybivers < 0) {
        r->handler_module = NULL;
        return HANDLER_FINISHED;
    }
    hctx->hybivers = hybivers;
    if (0 == hybivers) {
        DEBUG_LOG_INFO("WebSocket Version = %s", "hybi-00");
    }
    else {
        DEBUG_LOG_INFO("WebSocket Version = %d", hybivers);
    }

    hctx->gw.opts.backend     = BACKEND_PROXY; /*(act proxy-like)*/
    hctx->gw.opts.pdata       = hctx;
    hctx->gw.opts.parse       = wstunnel_recv_parse;
    hctx->gw.stdin_append     = wstunnel_stdin_append;
    hctx->gw.create_env       = wstunnel_create_env;
    hctx->gw.handler_ctx_free = wstunnel_handler_ctx_free;
    hctx->gw.backend_error    = wstunnel_backend_error;
    hctx->gw.response         = chunk_buffer_acquire();

    hctx->frame.state         = MOD_WEBSOCKET_FRAME_STATE_INIT;
    hctx->frame.ctl.siz       = 0;
    hctx->frame.payload       = chunk_buffer_acquire();

    unsigned int binary = hctx->conf.frame_type; /*(0 = "text"; 1 = "binary")*/
    if (!binary) {
        const buffer *vb =
          http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Sec-WebSocket-Protocol"));
        if (NULL != vb) {
            for (const char *s = vb->ptr; *s; ++s) {
                while (*s==' '||*s=='\t'||*s=='\r'||*s=='\n') ++s;
                if (buffer_eq_icase_ssn(s, CONST_STR_LEN("binary"))) {
                    s += sizeof("binary")-1;
                    while (*s==' '||*s=='\t'||*s=='\r'||*s=='\n') ++s;
                    if (*s==','||*s=='\0') {
                        hctx->subproto = 1;
                        binary = 1;
                        break;
                    }
                }
                else if (buffer_eq_icase_ssn(s, CONST_STR_LEN("base64"))) {
                    s += sizeof("base64")-1;
                    while (*s==' '||*s=='\t'||*s=='\r'||*s=='\n') ++s;
                    if (*s==','||*s=='\0') {
                        hctx->subproto = -1;
                        break;
                    }
                }
                s = strchr(s, ',');
                if (NULL == s) break;
            }
        }
    }

    if (binary) {
        DEBUG_LOG_INFO("%s", "will recv binary data from backend");
        hctx->frame.type         = MOD_WEBSOCKET_FRAME_TYPE_BIN;
        hctx->frame.type_before  = MOD_WEBSOCKET_FRAME_TYPE_BIN;
        hctx->frame.type_backend = MOD_WEBSOCKET_FRAME_TYPE_BIN;
    }
    else {
        DEBUG_LOG_INFO("%s", "will recv text data from backend");
        hctx->frame.type         = MOD_WEBSOCKET_FRAME_TYPE_TEXT;
        hctx->frame.type_before  = MOD_WEBSOCKET_FRAME_TYPE_TEXT;
        hctx->frame.type_backend = MOD_WEBSOCKET_FRAME_TYPE_TEXT;
    }

    return HANDLER_GO_ON;
}

static handler_t mod_wstunnel_check_extension(request_st * const r, void *p_d) {
    plugin_data *p = p_d;
    handler_t rc;

    if (NULL != r->handler_module)
        return HANDLER_GO_ON;
  if (r->http_version > HTTP_VERSION_1_1) {
    if (!r->h2_connect_ext)
        return HANDLER_GO_ON;
  }
  else {
    if (r->http_method != HTTP_METHOD_GET)
        return HANDLER_GO_ON;
    if (r->http_version != HTTP_VERSION_1_1)
        return HANDLER_GO_ON;

    /*
     * Connection: upgrade, keep-alive, ...
     * Upgrade: WebSocket, ...
     */
    const buffer *vb;
    vb = http_header_request_get(r, HTTP_HEADER_UPGRADE, CONST_STR_LEN("Upgrade"));
    if (NULL == vb
        || !http_header_str_contains_token(BUF_PTR_LEN(vb), CONST_STR_LEN("websocket")))
        return HANDLER_GO_ON;
    vb = http_header_request_get(r, HTTP_HEADER_CONNECTION, CONST_STR_LEN("Connection"));
    if (NULL == vb
        || !http_header_str_contains_token(BUF_PTR_LEN(vb), CONST_STR_LEN("upgrade")))
        return HANDLER_GO_ON;
  }

    mod_wstunnel_patch_config(r, p);
    if (NULL == p->conf.gw.exts) return HANDLER_GO_ON;

    rc = gw_check_extension(r, (gw_plugin_data *)p, 1, sizeof(handler_ctx));
    return (HANDLER_GO_ON == rc && r->handler_module == p->self)
      ? wstunnel_handler_setup(r, p)
      : rc;
}

TRIGGER_FUNC(mod_wstunnel_handle_trigger) {
    const plugin_data * const p = p_d;
    const unix_time64_t cur_ts = log_monotonic_secs + 1;

    gw_handle_trigger(srv, p_d);

    for (connection *con = srv->conns; con; con = con->next) {
        request_st * const r = &con->request;
        handler_ctx *hctx = r->plugin_ctx[p->id];
        if (NULL == hctx || r->handler_module != p->self)
            continue;

        if (hctx->gw.state != GW_STATE_WRITE && hctx->gw.state != GW_STATE_READ)
            continue;

        if (cur_ts - con->read_idle_ts > r->conf.max_read_idle) {
            DEBUG_LOG_INFO("timeout client (fd=%d)", con->fd);
            mod_wstunnel_frame_send(hctx,MOD_WEBSOCKET_FRAME_TYPE_CLOSE,NULL,0);
            gw_handle_request_reset(r, p_d);
            joblist_append(con);
            /* avoid server.c closing connection with error due to max_read_idle
             * (might instead run joblist after plugins_call_handle_trigger())*/
            con->read_idle_ts = cur_ts;
            continue;
        }

        if (0 != hctx->hybivers
            && hctx->conf.ping_interval > 0
            && (int32_t)hctx->conf.ping_interval + hctx->ping_ts < cur_ts) {
            hctx->ping_ts = cur_ts;
            mod_wstunnel_frame_send(hctx, MOD_WEBSOCKET_FRAME_TYPE_PING, CONST_STR_LEN("ping"));
            joblist_append(con);
            continue;
        }
    }

    return HANDLER_GO_ON;
}


__attribute_cold__
int mod_wstunnel_plugin_init(plugin *p);
int mod_wstunnel_plugin_init(plugin *p) {
    p->version           = LIGHTTPD_VERSION_ID;
    p->name              = "wstunnel";
    p->init              = mod_wstunnel_init;
    p->cleanup           = gw_free;
    p->set_defaults      = mod_wstunnel_set_defaults;
    p->handle_request_reset = gw_handle_request_reset;
    p->handle_uri_clean  = mod_wstunnel_check_extension;
    p->handle_subrequest = gw_handle_subrequest;
    p->handle_trigger    = mod_wstunnel_handle_trigger;
    p->handle_waitpid    = gw_handle_waitpid_cb;
    return 0;
}




/*
 * modified from Norio Kobota mod_websocket_handshake.c
 */

#ifdef _MOD_WEBSOCKET_SPEC_IETF_00_

#include "sys-crypto-md.h"  /* lighttpd */
#include "sys-endian.h"     /* lighttpd */

static int get_key3(request_st * const r, char *buf, uint32_t bytes) {
    /* 8 bytes should have been sent with request
     * for draft-ietf-hybi-thewebsocketprotocol-00 */
    chunkqueue *cq = &r->reqbody_queue;
    /*(caller should ensure bytes available prior to calling this routine)*/
    /*assert(chunkqueue_length(cq) >= 8);*/
    /*assert(8 == bytes);*/
    return chunkqueue_read_data(cq, buf, bytes, r->conf.errh);
}

static int get_key_number(uint32_t *ret, const buffer *b) {
    const char * const s = b->ptr;
    size_t j = 0;
    unsigned long n;
    uint32_t sp = 0;
    char tmp[10 + 1]; /* #define UINT32_MAX_STRLEN 10 */

    for (size_t i = 0, used = buffer_clen(b); i < used; ++i) {
        if (light_isdigit(s[i])) {
            tmp[j] = s[i];
            if (++j >= sizeof(tmp)) return -1;
        }
        else if (s[i] == ' ') ++sp; /* count num spaces */
    }
    tmp[j] = '\0';
    n = strtoul(tmp, NULL, 10);
    if (n > UINT32_MAX || 0 == sp || !light_isdigit(*tmp)) return -1;
    *ret = (uint32_t)n / sp;
    return 0;
}

static int create_MD5_sum(request_st * const r) {
    uint32_t buf[4]; /* MD5 binary hash len */

    const buffer *key1 =
      http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Sec-WebSocket-Key1"));
    const buffer *key2 =
      http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Sec-WebSocket-Key2"));

    if (NULL == key1 || get_key_number(buf+0, key1) < 0 ||
        NULL == key2 || get_key_number(buf+1, key2) < 0 ||
        get_key3(r, (char *)(buf+2), 2*sizeof(uint32_t)) < 0) {
        return -1;
    }
  #ifdef __BIG_ENDIAN__
  #define ws_htole32(s,u)\
    (s)[0]=((u)>>24);    \
    (s)[1]=((u)>>16);    \
    (s)[2]=((u)>>8);     \
    (s)[3]=((u))
    uint32_t u;
    u = buf[0];
    ws_htole32((unsigned char *)(buf+0), u);
    u = buf[1];
    ws_htole32((unsigned char *)(buf+1), u);
  #endif
    /*(overwrite buf[] with result)*/
    MD5_once((unsigned char *)buf, buf, sizeof(buf));
    chunkqueue_append_mem(&r->write_queue, (char *)buf, sizeof(buf));
    return 0;
}

static int create_response_ietf_00(handler_ctx *hctx) {
    request_st * const r = hctx->gw.r;

    /* "Origin" header is preferred
     * ("Sec-WebSocket-Origin" is from older drafts of websocket spec) */
    const buffer *origin = http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Origin"));
    if (NULL == origin) {
        origin =
          http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Sec-WebSocket-Origin"));
    }
    if (NULL == origin) {
        DEBUG_LOG_ERR("%s", "Origin header is invalid");
        return -1;
    }
    if (!r->http_host || buffer_is_blank(r->http_host)) {
        DEBUG_LOG_ERR("%s", "Host header does not exist");
        return -1;
    }

    /* calc MD5 sum from keys */
    if (create_MD5_sum(r) < 0) {
        DEBUG_LOG_ERR("%s", "Sec-WebSocket-Key is invalid");
        return -1;
    }

    http_header_response_set(r, HTTP_HEADER_UPGRADE,
                             CONST_STR_LEN("Upgrade"),
                             CONST_STR_LEN("websocket"));
  #if 0 /*(added later in http_response_write_header())*/
    http_header_response_append(r, HTTP_HEADER_CONNECTION,
                                CONST_STR_LEN("Connection"),
                                CONST_STR_LEN("upgrade"));
  #endif
  #if 0 /*(Sec-WebSocket-Origin header is not required for hybi-00)*/
    /* Note: it is insecure to simply reflect back origin provided by client
     * (if admin did not configure restricted list of valid origins)
     * (see wstunnel_check_request()) */
    http_header_response_set(r, HTTP_HEADER_OTHER,
                             CONST_STR_LEN("Sec-WebSocket-Origin"),
                             BUF_PTR_LEN(origin));
  #endif

    buffer * const value =
      http_header_response_set_ptr(r, HTTP_HEADER_OTHER,
                                   CONST_STR_LEN("Sec-WebSocket-Location"));
    if (buffer_is_equal_string(&r->uri.scheme, CONST_STR_LEN("https")))
        buffer_copy_string_len(value, CONST_STR_LEN("wss://"));
    else
        buffer_copy_string_len(value, CONST_STR_LEN("ws://"));
    buffer_append_str2(value, BUF_PTR_LEN(r->http_host),
                              BUF_PTR_LEN(&r->uri.path));
    return 0;
}

#endif /* _MOD_WEBSOCKET_SPEC_IETF_00_ */


#ifdef _MOD_WEBSOCKET_SPEC_RFC_6455_

#include "sys-crypto-md.h"  /* lighttpd */
#include "base64.h"         /* lighttpd */

static int create_response_rfc_6455(handler_ctx *hctx) {
    request_st * const r = hctx->gw.r;
  if (r->http_version == HTTP_VERSION_1_1) {
    SHA_CTX sha;
    unsigned char sha_digest[SHA_DIGEST_LENGTH];

    const buffer *value_wskey =
      http_header_request_get(r, HTTP_HEADER_OTHER, CONST_STR_LEN("Sec-WebSocket-Key"));
    if (NULL == value_wskey) {
        DEBUG_LOG_ERR("%s", "Sec-WebSocket-Key is invalid");
        return -1;
    }

    /* get SHA1 hash of key */
    /* refer: RFC-6455 Sec.1.3 Opening Handshake */
    SHA1_Init(&sha);
    SHA1_Update(&sha, (const unsigned char *)BUF_PTR_LEN(value_wskey));
    SHA1_Update(&sha, (const unsigned char *)CONST_STR_LEN("258EAFA5-E914-47DA-95CA-C5AB0DC85B11"));
    SHA1_Final(sha_digest, &sha);

    http_header_response_set(r, HTTP_HEADER_UPGRADE,
                             CONST_STR_LEN("Upgrade"),
                             CONST_STR_LEN("websocket"));
  #if 0 /*(added later in http_response_write_header())*/
    http_header_response_append(r, HTTP_HEADER_CONNECTION,
                                CONST_STR_LEN("Connection"),
                                CONST_STR_LEN("upgrade"));
  #endif

    buffer * const value =
      http_header_response_set_ptr(r, HTTP_HEADER_OTHER,
                                   CONST_STR_LEN("Sec-WebSocket-Accept"));
    buffer_append_base64_encode(value, sha_digest, SHA_DIGEST_LENGTH, BASE64_STANDARD);
  }

    if (hctx->frame.type == MOD_WEBSOCKET_FRAME_TYPE_BIN)
        http_header_response_set(r, HTTP_HEADER_OTHER,
                                 CONST_STR_LEN("Sec-WebSocket-Protocol"),
                                 CONST_STR_LEN("binary"));
    else if (-1 == hctx->subproto)
        http_header_response_set(r, HTTP_HEADER_OTHER,
                                 CONST_STR_LEN("Sec-WebSocket-Protocol"),
                                 CONST_STR_LEN("base64"));

    return 0;
}

#endif /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */


handler_t mod_wstunnel_handshake_create_response(handler_ctx *hctx) {
    request_st * const r = hctx->gw.r;
  #ifdef _MOD_WEBSOCKET_SPEC_RFC_6455_
    if (hctx->hybivers >= 8) {
        DEBUG_LOG_DEBUG("%s", "send handshake response");
        if (0 != create_response_rfc_6455(hctx)) {
            r->http_status = 400; /* Bad Request */
            return HANDLER_ERROR;
        }
        return HANDLER_GO_ON;
    }
  #endif /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */

  #ifdef _MOD_WEBSOCKET_SPEC_IETF_00_
    if (hctx->hybivers == 0 && r->http_version == HTTP_VERSION_1_1) {
      #ifdef _MOD_WEBSOCKET_SPEC_IETF_00_
        /* 8 bytes should have been sent with request
         * for draft-ietf-hybi-thewebsocketprotocol-00 */
        chunkqueue *cq = &r->reqbody_queue;
        if (chunkqueue_length(cq) < 8)
            return HANDLER_WAIT_FOR_EVENT;
      #endif /* _MOD_WEBSOCKET_SPEC_IETF_00_ */

        DEBUG_LOG_DEBUG("%s", "send handshake response");
        if (0 != create_response_ietf_00(hctx)) {
            r->http_status = 400; /* Bad Request */
            return HANDLER_ERROR;
        }
        return HANDLER_GO_ON;
    }
  #endif /* _MOD_WEBSOCKET_SPEC_IETF_00_ */

    DEBUG_LOG_ERR("%s", "not supported WebSocket Version");
    r->http_status = 503; /* Service Unavailable */
    return HANDLER_ERROR;
}




/*
 * modified from Norio Kobota mod_websocket_frame.c
 */

#include "base64.h"     /* lighttpd */
#include "http_chunk.h" /* lighttpd */

#define MOD_WEBSOCKET_BUFMAX (0x0fffff)

#ifdef _MOD_WEBSOCKET_SPEC_IETF_00_

#include <stdlib.h>
static int send_ietf_00(handler_ctx *hctx, mod_wstunnel_frame_type_t type, const char *payload, size_t siz) {
    static const char head =  0; /* 0x00 */
    static const char tail = ~0; /* 0xff */
    request_st * const r = hctx->gw.r;
    char *mem;
    size_t len;

    switch (type) {
    case MOD_WEBSOCKET_FRAME_TYPE_TEXT:
        if (0 == siz) return 0;
        http_chunk_append_mem(r, &head, 1);
        http_chunk_append_mem(r, payload, siz);
        http_chunk_append_mem(r, &tail, 1);
        len = siz+2;
        break;
    case MOD_WEBSOCKET_FRAME_TYPE_BIN:
        if (0 == siz) return 0;
        http_chunk_append_mem(r, &head, 1);
        len = 4*(siz/3)+4+1;
        /* avoid accumulating too much data in memory; send to tmpfile */
        mem = ck_malloc(len);
        len=li_to_base64(mem,len,(unsigned char *)payload,siz,BASE64_STANDARD);
        http_chunk_append_mem(r, mem, len);
        free(mem);
        http_chunk_append_mem(r, &tail, 1);
        len += 2;
        break;
    case MOD_WEBSOCKET_FRAME_TYPE_CLOSE:
        http_chunk_append_mem(r, &tail, 1);
        http_chunk_append_mem(r, &head, 1);
        len = 2;
        break;
    default:
        DEBUG_LOG_ERR("%s", "invalid frame type");
        return -1;
    }
    DEBUG_LOG_DEBUG("send data to client (fd=%d), frame size=%zx",
                    r->con->fd, len);
    return 0;
}

static int recv_ietf_00(handler_ctx *hctx) {
    request_st * const r = hctx->gw.r;
    chunkqueue *cq = &r->reqbody_queue;
    buffer *payload = hctx->frame.payload;
    char *mem;
    DEBUG_LOG_DEBUG("recv data from client (fd=%d), size=%llx",
                    r->con->fd, (long long)chunkqueue_length(cq));
    for (chunk *c = cq->first; c; c = c->next) {
        char *frame = c->mem->ptr+c->offset;
        /*(chunk_remaining_length() on MEM_CHUNK)*/
        size_t flen = (size_t)(buffer_clen(c->mem) - c->offset);
        /*(FILE_CHUNK not handled, but might need to add support)*/
        force_assert(c->type == MEM_CHUNK);
        for (size_t i = 0; i < flen; ) {
            switch (hctx->frame.state) {
            case MOD_WEBSOCKET_FRAME_STATE_INIT:
                hctx->frame.ctl.siz = 0;
                if (frame[i] == 0x00) {
                    hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_READ_PAYLOAD;
                    i++;
                }
                else if (((unsigned char *)frame)[i] == 0xff) {
                    DEBUG_LOG_DEBUG("%s", "recv close frame");
                    return -1;
                }
                else {
                    DEBUG_LOG_DEBUG("%s", "recv invalid frame");
                    return -1;
                }
                break;
            case MOD_WEBSOCKET_FRAME_STATE_READ_PAYLOAD:
                mem = (char *)memchr(frame+i, 0xff, flen - i);
                if (mem == NULL) {
                    DEBUG_LOG_DEBUG("got continuous payload, size=%zx", flen-i);
                    hctx->frame.ctl.siz += flen - i;
                    if (hctx->frame.ctl.siz > MOD_WEBSOCKET_BUFMAX) {
                        DEBUG_LOG_WARN("frame size has been exceeded: %x",
                                       MOD_WEBSOCKET_BUFMAX);
                        return -1;
                    }
                    buffer_append_string_len(payload, frame+i, flen - i);
                    i += flen - i;
                }
                else {
                    DEBUG_LOG_DEBUG("got final payload, size=%zx",
                                    mem - (frame+i));
                    hctx->frame.ctl.siz += (mem - (frame+i));
                    if (hctx->frame.ctl.siz > MOD_WEBSOCKET_BUFMAX) {
                        DEBUG_LOG_WARN("frame size has been exceeded: %x",
                                       MOD_WEBSOCKET_BUFMAX);
                        return -1;
                    }
                    buffer_append_string_len(payload, frame+i, mem - (frame+i));
                    i += (mem - (frame+i));
                    hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_INIT;
                }
                i++;
                if (hctx->frame.type == MOD_WEBSOCKET_FRAME_TYPE_TEXT
                    && !buffer_is_unset(payload)) { /*XXX: buffer_is_blank?*/
                    hctx->frame.ctl.siz = 0;
                    chunkqueue_append_buffer(&hctx->gw.wb, payload);
                    /*buffer_clear(payload);*//*chunkqueue_append_buffer clear*/
                }
                else {
                    if (hctx->frame.state == MOD_WEBSOCKET_FRAME_STATE_INIT
                        && !buffer_is_unset(payload)) {/*XXX: buffer_is_blank?*/
                        buffer *b;
                        size_t len = buffer_clen(payload);
                        len = (len+3)/4*3+1;
                        chunkqueue_get_memory(&hctx->gw.wb, &len);
                        b = hctx->gw.wb.last->mem;
                        len = buffer_clen(b);
                        DEBUG_LOG_DEBUG("try to base64 decode: %s",
                                        payload->ptr);
                        if (NULL ==
                            buffer_append_base64_decode(b, BUF_PTR_LEN(payload),
                                                        BASE64_STANDARD)) {
                            DEBUG_LOG_ERR("%s", "fail to base64-decode");
                            return -1;
                        }
                        buffer_clear(payload);
                        /*chunkqueue_use_memory()*/
                        hctx->gw.wb.bytes_in += buffer_clen(b)-len;
                    }
                }
                break;
            default: /* never reach */
                DEBUG_LOG_ERR("%s", "BUG: unknown state");
                return -1;
            }
        }
    }
    /* XXX: should add ability to handle and preserve partial frames above */
    /*(not chunkqueue_reset(); do not reset cq->bytes_in, cq->bytes_out)*/
    chunkqueue_mark_written(cq, chunkqueue_length(cq));
    return 0;
}

#endif /* _MOD_WEBSOCKET_SPEC_IETF_00_ */


#ifdef _MOD_WEBSOCKET_SPEC_RFC_6455_

#define MOD_WEBSOCKET_OPCODE_CONT   0x00
#define MOD_WEBSOCKET_OPCODE_TEXT   0x01
#define MOD_WEBSOCKET_OPCODE_BIN    0x02
#define MOD_WEBSOCKET_OPCODE_CLOSE  0x08
#define MOD_WEBSOCKET_OPCODE_PING   0x09
#define MOD_WEBSOCKET_OPCODE_PONG   0x0A

#define MOD_WEBSOCKET_FRAME_LEN16   0x7E
#define MOD_WEBSOCKET_FRAME_LEN63   0x7F
#define MOD_WEBSOCKET_FRAME_LEN16_CNT  2
#define MOD_WEBSOCKET_FRAME_LEN63_CNT  8

static int send_rfc_6455(handler_ctx *hctx, mod_wstunnel_frame_type_t type, const char *payload, size_t siz) {
    char mem[10];
    size_t len;

    /* allowed null payload for ping, pong, close frame */
    if (payload == NULL && (   type == MOD_WEBSOCKET_FRAME_TYPE_TEXT
                            || type == MOD_WEBSOCKET_FRAME_TYPE_BIN   )) {
        return -1;
    }

    switch (type) {
    case MOD_WEBSOCKET_FRAME_TYPE_TEXT:
        mem[0] = (char)(0x80 | MOD_WEBSOCKET_OPCODE_TEXT);
        DEBUG_LOG_DEBUG("%s", "type = text");
        break;
    case MOD_WEBSOCKET_FRAME_TYPE_BIN:
        mem[0] = (char)(0x80 | MOD_WEBSOCKET_OPCODE_BIN);
        DEBUG_LOG_DEBUG("%s", "type = binary");
        break;
    case MOD_WEBSOCKET_FRAME_TYPE_PING:
        mem[0] = (char) (0x80 | MOD_WEBSOCKET_OPCODE_PING);
        DEBUG_LOG_DEBUG("%s", "type = ping");
        break;
    case MOD_WEBSOCKET_FRAME_TYPE_PONG:
        mem[0] = (char)(0x80 | MOD_WEBSOCKET_OPCODE_PONG);
        DEBUG_LOG_DEBUG("%s", "type = pong");
        break;
    case MOD_WEBSOCKET_FRAME_TYPE_CLOSE:
    default:
        mem[0] = (char)(0x80 | MOD_WEBSOCKET_OPCODE_CLOSE);
        DEBUG_LOG_DEBUG("%s", "type = close");
        break;
    }

    DEBUG_LOG_DEBUG("payload size=%zx", siz);
    if (siz < MOD_WEBSOCKET_FRAME_LEN16) {
        mem[1] = siz;
        len = 2;
    }
    else if (siz <= UINT16_MAX) {
        mem[1] = MOD_WEBSOCKET_FRAME_LEN16;
        mem[2] = (siz >> 8) & 0xff;
        mem[3] = siz & 0xff;
        len = 1+MOD_WEBSOCKET_FRAME_LEN16_CNT+1;
    }
    else {
        mem[1] = MOD_WEBSOCKET_FRAME_LEN63;
        mem[2] = 0;
        mem[3] = 0;
        mem[4] = 0;
        mem[5] = 0;
        mem[6] = (siz >> 24) & 0xff;
        mem[7] = (siz >> 16) & 0xff;
        mem[8] = (siz >> 8) & 0xff;
        mem[9] = siz & 0xff;
        len = 1+MOD_WEBSOCKET_FRAME_LEN63_CNT+1;
    }
    request_st * const r = hctx->gw.r;
    http_chunk_append_mem(r, mem, len);
    if (siz) http_chunk_append_mem(r, payload, siz);
    DEBUG_LOG_DEBUG("send data to client (fd=%d), frame size=%zx",
                    r->con->fd, len+siz);
    return 0;
}

static void unmask_payload(handler_ctx *hctx) {
    buffer * const b = hctx->frame.payload;
    for (size_t i = 0, used = buffer_clen(b); i < used; ++i) {
        b->ptr[i] ^= hctx->frame.ctl.mask[hctx->frame.ctl.mask_cnt];
        hctx->frame.ctl.mask_cnt = (hctx->frame.ctl.mask_cnt + 1) % 4;
    }
}

static int recv_rfc_6455(handler_ctx *hctx) {
    request_st * const r = hctx->gw.r;
    chunkqueue *cq = &r->reqbody_queue;
    buffer *payload = hctx->frame.payload;
    DEBUG_LOG_DEBUG("recv data from client (fd=%d), size=%llx",
                    r->con->fd, (long long)chunkqueue_length(cq));
    for (chunk *c = cq->first; c; c = c->next) {
        char *frame = c->mem->ptr+c->offset;
        /*(chunk_remaining_length() on MEM_CHUNK)*/
        size_t flen = (size_t)(buffer_clen(c->mem) - c->offset);
        /*(FILE_CHUNK not handled, but might need to add support)*/
        force_assert(c->type == MEM_CHUNK);
        for (size_t i = 0; i < flen; ) {
            switch (hctx->frame.state) {
            case MOD_WEBSOCKET_FRAME_STATE_INIT:
                switch (frame[i] & 0x0f) {
                case MOD_WEBSOCKET_OPCODE_CONT:
                    DEBUG_LOG_DEBUG("%s", "type = continue");
                    hctx->frame.type = hctx->frame.type_before;
                    break;
                case MOD_WEBSOCKET_OPCODE_TEXT:
                    DEBUG_LOG_DEBUG("%s", "type = text");
                    hctx->frame.type = MOD_WEBSOCKET_FRAME_TYPE_TEXT;
                    hctx->frame.type_before = hctx->frame.type;
                    break;
                case MOD_WEBSOCKET_OPCODE_BIN:
                    DEBUG_LOG_DEBUG("%s", "type = binary");
                    hctx->frame.type = MOD_WEBSOCKET_FRAME_TYPE_BIN;
                    hctx->frame.type_before = hctx->frame.type;
                    break;
                case MOD_WEBSOCKET_OPCODE_PING:
                    DEBUG_LOG_DEBUG("%s", "type = ping");
                    hctx->frame.type = MOD_WEBSOCKET_FRAME_TYPE_PING;
                    break;
                case MOD_WEBSOCKET_OPCODE_PONG:
                    DEBUG_LOG_DEBUG("%s", "type = pong");
                    hctx->frame.type = MOD_WEBSOCKET_FRAME_TYPE_PONG;
                    break;
                case MOD_WEBSOCKET_OPCODE_CLOSE:
                    DEBUG_LOG_DEBUG("%s", "type = close");
                    hctx->frame.type = MOD_WEBSOCKET_FRAME_TYPE_CLOSE;
                    return -1;
                    break;
                default:
                    DEBUG_LOG_ERR("%s", "type is invalid");
                    return -1;
                    break;
                }
                i++;
                hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_READ_LENGTH;
                break;
            case MOD_WEBSOCKET_FRAME_STATE_READ_LENGTH:
                if ((frame[i] & 0x80) != 0x80) {
                    DEBUG_LOG_ERR("%s", "payload was not masked");
                    return -1;
                }
                hctx->frame.ctl.mask_cnt = 0;
                hctx->frame.ctl.siz = (uint64_t)(frame[i] & 0x7f);
                if (hctx->frame.ctl.siz == 0) {
                    DEBUG_LOG_DEBUG("specified payload size=%llx",
                                    (unsigned long long)hctx->frame.ctl.siz);
                    hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_READ_MASK;
                }
                else if (hctx->frame.ctl.siz == MOD_WEBSOCKET_FRAME_LEN16) {
                    hctx->frame.ctl.siz = 0;
                    hctx->frame.ctl.siz_cnt = MOD_WEBSOCKET_FRAME_LEN16_CNT;
                    hctx->frame.state =
                        MOD_WEBSOCKET_FRAME_STATE_READ_EX_LENGTH;
                }
                else if (hctx->frame.ctl.siz == MOD_WEBSOCKET_FRAME_LEN63) {
                    hctx->frame.ctl.siz = 0;
                    hctx->frame.ctl.siz_cnt = MOD_WEBSOCKET_FRAME_LEN63_CNT;
                    hctx->frame.state =
                        MOD_WEBSOCKET_FRAME_STATE_READ_EX_LENGTH;
                }
                else {
                    DEBUG_LOG_DEBUG("specified payload size=%llx",
                                    (unsigned long long)hctx->frame.ctl.siz);
                    hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_READ_MASK;
                }
                i++;
                break;
            case MOD_WEBSOCKET_FRAME_STATE_READ_EX_LENGTH:
                hctx->frame.ctl.siz =
                    (hctx->frame.ctl.siz << 8) + (frame[i] & 0xff);
                hctx->frame.ctl.siz_cnt--;
                if (hctx->frame.ctl.siz_cnt <= 0) {
                    if (hctx->frame.type == MOD_WEBSOCKET_FRAME_TYPE_PING &&
                        hctx->frame.ctl.siz > MOD_WEBSOCKET_BUFMAX) {
                        DEBUG_LOG_WARN("frame size has been exceeded: %x",
                                       MOD_WEBSOCKET_BUFMAX);
                        return -1;
                    }
                    DEBUG_LOG_DEBUG("specified payload size=%llx",
                                    (unsigned long long)hctx->frame.ctl.siz);
                    hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_READ_MASK;
                }
                i++;
                break;
            case MOD_WEBSOCKET_FRAME_STATE_READ_MASK:
                hctx->frame.ctl.mask[hctx->frame.ctl.mask_cnt] = frame[i];
                hctx->frame.ctl.mask_cnt++;
                if (hctx->frame.ctl.mask_cnt >= MOD_WEBSOCKET_MASK_CNT) {
                    hctx->frame.ctl.mask_cnt = 0;
                    if (hctx->frame.type == MOD_WEBSOCKET_FRAME_TYPE_PING &&
                        hctx->frame.ctl.siz == 0) {
                        mod_wstunnel_frame_send(hctx,
                                                MOD_WEBSOCKET_FRAME_TYPE_PONG,
                                                NULL, 0);
                    }
                    if (hctx->frame.ctl.siz == 0) {
                        hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_INIT;
                    }
                    else {
                        hctx->frame.state =
                            MOD_WEBSOCKET_FRAME_STATE_READ_PAYLOAD;
                    }
                }
                i++;
                break;
            case MOD_WEBSOCKET_FRAME_STATE_READ_PAYLOAD:
                /* hctx->frame.ctl.siz <= SIZE_MAX */
                if (hctx->frame.ctl.siz <= flen - i) {
                    DEBUG_LOG_DEBUG("read payload, size=%llx",
                                    (unsigned long long)hctx->frame.ctl.siz);
                    buffer_append_string_len(payload, frame+i, (size_t)
                                             (hctx->frame.ctl.siz & SIZE_MAX));
                    i += (size_t)(hctx->frame.ctl.siz & SIZE_MAX);
                    hctx->frame.ctl.siz = 0;
                    hctx->frame.state = MOD_WEBSOCKET_FRAME_STATE_INIT;
                    DEBUG_LOG_DEBUG("rest of frame size=%zx", flen - i);
                /* SIZE_MAX < hctx->frame.ctl.siz */
                }
                else {
                    DEBUG_LOG_DEBUG("read payload, size=%zx", flen - i);
                    buffer_append_string_len(payload, frame+i, flen - i);
                    hctx->frame.ctl.siz -= flen - i;
                    i += flen - i;
                    DEBUG_LOG_DEBUG("rest of payload size=%llx",
                                    (unsigned long long)hctx->frame.ctl.siz);
                }
                switch (hctx->frame.type) {
                case MOD_WEBSOCKET_FRAME_TYPE_TEXT:
                case MOD_WEBSOCKET_FRAME_TYPE_BIN:
                  {
                    unmask_payload(hctx);
                    chunkqueue_append_buffer(&hctx->gw.wb, payload);
                    /*buffer_clear(payload);*//*chunkqueue_append_buffer clear*/
                    break;
                  }
                case MOD_WEBSOCKET_FRAME_TYPE_PING:
                    if (hctx->frame.ctl.siz == 0) {
                        unmask_payload(hctx);
                        mod_wstunnel_frame_send(hctx,
                          MOD_WEBSOCKET_FRAME_TYPE_PONG,
                          payload->ptr, buffer_clen(payload));
                        buffer_clear(payload);
                    }
                    break;
                case MOD_WEBSOCKET_FRAME_TYPE_PONG:
                    buffer_clear(payload);
                    break;
                case MOD_WEBSOCKET_FRAME_TYPE_CLOSE:
                default:
                    DEBUG_LOG_ERR("%s", "BUG: invalid frame type");
                    return -1;
                }
                break;
            default:
                DEBUG_LOG_ERR("%s", "BUG: invalid state");
                return -1;
            }
        }
    }
    /* XXX: should add ability to handle and preserve partial frames above */
    /*(not chunkqueue_reset(); do not reset cq->bytes_in, cq->bytes_out)*/
    chunkqueue_mark_written(cq, chunkqueue_length(cq));
    return 0;
}

#endif /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */


int mod_wstunnel_frame_send(handler_ctx *hctx, mod_wstunnel_frame_type_t type,
                             const char *payload, size_t siz) {
  #ifdef _MOD_WEBSOCKET_SPEC_RFC_6455_
    if (hctx->hybivers >= 8) return send_rfc_6455(hctx, type, payload, siz);
  #endif /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */
  #ifdef _MOD_WEBSOCKET_SPEC_IETF_00_
    if (0 == hctx->hybivers) return send_ietf_00(hctx, type, payload, siz);
  #endif /* _MOD_WEBSOCKET_SPEC_IETF_00_ */
    return -1;
}

int mod_wstunnel_frame_recv(handler_ctx *hctx) {
  #ifdef _MOD_WEBSOCKET_SPEC_RFC_6455_
    if (hctx->hybivers >= 8) return recv_rfc_6455(hctx);
  #endif /* _MOD_WEBSOCKET_SPEC_RFC_6455_ */
  #ifdef _MOD_WEBSOCKET_SPEC_IETF_00_
    if (0 == hctx->hybivers) return recv_ietf_00(hctx);
  #endif /* _MOD_WEBSOCKET_SPEC_IETF_00_ */
    return -1;
}
