res_http_websocket.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2012, Digium, Inc.
 *
 * Joshua Colp <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief WebSocket support for the Asterisk internal HTTP server
 *
 * \author Joshua Colp <[email protected]>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include "asterisk/module.h"
#include "asterisk/http.h"
#include "asterisk/astobj2.h"
#include "asterisk/strings.h"
#include "asterisk/file.h"
#include "asterisk/unaligned.h"
#include "asterisk/uri.h"
#include "asterisk/uuid.h"

#define AST_API_MODULE
#include "asterisk/http_websocket.h"

/*! \brief GUID used to compute the accept key, defined in the specifications */
#define WEBSOCKET_GUID "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"

/*! \brief Length of a websocket's client key */
#define CLIENT_KEY_SIZE 16

/*! \brief Number of buckets for registered protocols */
#define MAX_PROTOCOL_BUCKETS 7

#ifdef LOW_MEMORY
/*! \brief Size of the pre-determined buffer for WebSocket frames */
#define MAXIMUM_FRAME_SIZE 8192

/*! \brief Default reconstruction size for multi-frame payload reconstruction. If exceeded the next frame will start a
 *         payload.
 */
#define DEFAULT_RECONSTRUCTION_CEILING 8192

/*! \brief Maximum reconstruction size for multi-frame payload reconstruction. */
#define MAXIMUM_RECONSTRUCTION_CEILING 8192
#else
/*! \brief Size of the pre-determined buffer for WebSocket frames */
#define MAXIMUM_FRAME_SIZE 65535

/*! \brief Default reconstruction size for multi-frame payload reconstruction. If exceeded the next frame will start a
 *         payload.
 */
#define DEFAULT_RECONSTRUCTION_CEILING MAXIMUM_FRAME_SIZE

/*! \brief Maximum reconstruction size for multi-frame payload reconstruction. */
#define MAXIMUM_RECONSTRUCTION_CEILING MAXIMUM_FRAME_SIZE
#endif

/*! \brief Maximum size of a websocket frame header
 * 1 byte flags and opcode
 * 1 byte mask flag + payload len
 * 8 bytes max extended length
 * 4 bytes optional masking key
 * ... payload follows ...
 * */
#define MAX_WS_HDR_SZ 14
#define MIN_WS_HDR_SZ 2

/*! \brief Structure definition for session */
struct ast_websocket {
   struct ast_iostream *stream;        /*!< iostream of the connection */
   struct ast_sockaddr remote_address; /*!< Address of the remote client */
   struct ast_sockaddr local_address;  /*!< Our local address */
   enum ast_websocket_opcode opcode;   /*!< Cached opcode for multi-frame messages */
   size_t payload_len;                 /*!< Length of the payload */
   char *payload;                      /*!< Pointer to the payload */
   size_t reconstruct;                 /*!< Number of bytes before a reconstructed payload will be returned and a new one started */
   int timeout;                        /*!< The timeout for operations on the socket */
   unsigned int secure:1;              /*!< Bit to indicate that the transport is secure */
   unsigned int closing:1;             /*!< Bit to indicate that the session is in the process of being closed */
   unsigned int close_sent:1;          /*!< Bit to indicate that the session close opcode has been sent and no further data will be sent */
   struct websocket_client *client;    /*!< Client object when connected as a client websocket */
   char session_id[AST_UUID_STR_LEN];  /*!< The identifier for the websocket session */
   uint16_t close_status_code;         /*!< Status code sent in a CLOSE frame upon shutdown */
   char buf[MAXIMUM_FRAME_SIZE];     /*!< Fixed buffer for reading data into */
};

/*! \brief Hashing function for protocols */
static int protocol_hash_fn(const void *obj, const int flags)
{
   const struct ast_websocket_protocol *protocol = obj;
   const char *name = obj;

   return ast_str_case_hash(flags & OBJ_KEY ? name : protocol->name);
}

/*! \brief Comparison function for protocols */
static int protocol_cmp_fn(void *obj, void *arg, int flags)
{
   const struct ast_websocket_protocol *protocol1 = obj, *protocol2 = arg;
   const char *protocol = arg;

   return !strcasecmp(protocol1->name, flags & OBJ_KEY ? protocol : protocol2->name) ? CMP_MATCH | CMP_STOP : 0;
}

/*! \brief Destructor function for protocols */
static void protocol_destroy_fn(void *obj)
{
   struct ast_websocket_protocol *protocol = obj;
   ast_free(protocol->name);
}

/*! \brief Structure for a WebSocket server */
struct ast_websocket_server {
   struct ao2_container *protocols; /*!< Container for registered protocols */
};

static void websocket_server_dtor(void *obj)
{
   struct ast_websocket_server *server = obj;
   ao2_cleanup(server->protocols);
   server->protocols = NULL;
}

static struct ast_websocket_server *websocket_server_create_impl(void)
{
   RAII_VAR(struct ast_websocket_server *, server, NULL, ao2_cleanup);

   server = ao2_alloc(sizeof(*server), websocket_server_dtor);
   if (!server) {
      return NULL;
   }

   server->protocols = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0,
      MAX_PROTOCOL_BUCKETS, protocol_hash_fn, NULL, protocol_cmp_fn);
   if (!server->protocols) {
      return NULL;
   }

   ao2_ref(server, +1);
   return server;
}

static struct ast_websocket_server *websocket_server_internal_create(void)
{
   return websocket_server_create_impl();
}

struct ast_websocket_server *AST_OPTIONAL_API_NAME(ast_websocket_server_create)(void)
{
   return websocket_server_create_impl();
}

/*! \brief Destructor function for sessions */
static void session_destroy_fn(void *obj)
{
   struct ast_websocket *session = obj;

   if (session->stream) {
      ast_websocket_close(session, session->close_status_code);
      if (session->stream) {
         ast_iostream_close(session->stream);
         session->stream = NULL;
         ast_verb(2, "WebSocket connection %s '%s' closed\n", session->client ? "to" : "from",
            ast_sockaddr_stringify(&session->remote_address));
      }
   }

   ao2_cleanup(session->client);
   ast_free(session->payload);
}

struct ast_websocket_protocol *AST_OPTIONAL_API_NAME(ast_websocket_sub_protocol_alloc)(const char *name)
{
   struct ast_websocket_protocol *protocol;

   protocol = ao2_alloc(sizeof(*protocol), protocol_destroy_fn);
   if (!protocol) {
      return NULL;
   }

   protocol->name = ast_strdup(name);
   if (!protocol->name) {
      ao2_ref(protocol, -1);
      return NULL;
   }
   protocol->version = AST_WEBSOCKET_PROTOCOL_VERSION;

   return protocol;
}

int AST_OPTIONAL_API_NAME(ast_websocket_server_add_protocol)(struct ast_websocket_server *server, const char *name, ast_websocket_callback callback)
{
   struct ast_websocket_protocol *protocol;

   if (!server->protocols) {
      return -1;
   }

   protocol = ast_websocket_sub_protocol_alloc(name);
   if (!protocol) {
      return -1;
   }
   protocol->session_established = callback;

   if (ast_websocket_server_add_protocol2(server, protocol)) {
      ao2_ref(protocol, -1);
      return -1;
   }

   return 0;
}

int AST_OPTIONAL_API_NAME(ast_websocket_server_add_protocol2)(struct ast_websocket_server *server, struct ast_websocket_protocol *protocol)
{
   struct ast_websocket_protocol *existing;

   if (!server->protocols) {
      return -1;
   }

   if (protocol->version != AST_WEBSOCKET_PROTOCOL_VERSION) {
      ast_log(LOG_WARNING, "WebSocket could not register sub-protocol '%s': "
         "expected version '%u', got version '%u'\n",
         protocol->name, AST_WEBSOCKET_PROTOCOL_VERSION, protocol->version);
      return -1;
   }

   ao2_lock(server->protocols);

   /* Ensure a second protocol handler is not registered for the same protocol */
   existing = ao2_find(server->protocols, protocol->name, OBJ_KEY | OBJ_NOLOCK);
   if (existing) {
      ao2_ref(existing, -1);
      ao2_unlock(server->protocols);
      return -1;
   }

   ao2_link_flags(server->protocols, protocol, OBJ_NOLOCK);
   ao2_unlock(server->protocols);

   ast_verb(2, "WebSocket registered sub-protocol '%s'\n", protocol->name);
   ao2_ref(protocol, -1);

   return 0;
}

int AST_OPTIONAL_API_NAME(ast_websocket_server_remove_protocol)(struct ast_websocket_server *server, const char *name, ast_websocket_callback callback)
{
   struct ast_websocket_protocol *protocol;

   if (!(protocol = ao2_find(server->protocols, name, OBJ_KEY))) {
      return -1;
   }

   if (protocol->session_established != callback) {
      ao2_ref(protocol, -1);
      return -1;
   }

   ao2_unlink(server->protocols, protocol);
   ao2_ref(protocol, -1);

   ast_verb(2, "WebSocket unregistered sub-protocol '%s'\n", name);

   return 0;
}

/*! \brief Perform payload masking for client sessions */
static void websocket_mask_payload(struct ast_websocket *session, char *frame, char *payload, uint64_t payload_size)
{
   /* RFC 6455 5.1 - clients MUST mask frame data */
   if (session->client) {
      uint64_t i;
      uint8_t mask_key_idx;
      uint32_t mask_key = ast_random();
      uint8_t length = frame[1] & 0x7f;
      frame[1] |= 0x80; /* set mask bit to 1 */
      /* The mask key octet position depends on the length */
      mask_key_idx = length == 126 ? 4 : length == 127 ? 10 : 2;
      put_unaligned_uint32(&frame[mask_key_idx], mask_key);
      for (i = 0; i < payload_size; i++) {
         payload[i] ^= ((char *)&mask_key)[i % 4];
      }
   }
}


/*! \brief Close function for websocket session */
int AST_OPTIONAL_API_NAME(ast_websocket_close)(struct ast_websocket *session, uint16_t reason)
{
   enum ast_websocket_opcode opcode = AST_WEBSOCKET_OPCODE_CLOSE;
   /* The header is either 2 or 6 bytes and the
    * reason code takes up another 2 bytes */
   char frame[8] = { 0, };
   int header_size, fsize, res;

   if (session->close_sent) {
      return 0;
   }

   /* clients need space for an additional 4 byte masking key */
   header_size = session->client ? 6 : 2;
   fsize = header_size + 2;

   frame[0] = opcode | 0x80;
   frame[1] = 2; /* The reason code is always 2 bytes */

   /* If no reason has been specified assume 1000 which is normal closure */
   put_unaligned_uint16(&frame[header_size], htons(reason ? reason : 1000));

   websocket_mask_payload(session, frame, &frame[header_size], 2);

   session->closing = 1;
   session->close_sent = 1;

   ao2_lock(session);
   ast_iostream_set_timeout_inactivity(session->stream, session->timeout);
   res = ast_iostream_write(session->stream, frame, fsize);
   ast_iostream_set_timeout_disable(session->stream);

   /* If an error occurred when trying to close this connection explicitly terminate it now.
    * Doing so will cause the thread polling on it to wake up and terminate.
    */
   if (res != fsize) {
      ast_iostream_close(session->stream);
      session->stream = NULL;
      ast_verb(2, "WebSocket connection %s '%s' forcefully closed due to fatal write error\n",
         session->client ? "to" : "from", ast_sockaddr_stringify(&session->remote_address));
   }

   ao2_unlock(session);
   return res == sizeof(frame);
}

static const char *opcode_map[] = {
   [AST_WEBSOCKET_OPCODE_CONTINUATION] = "continuation",
   [AST_WEBSOCKET_OPCODE_TEXT] = "text",
   [AST_WEBSOCKET_OPCODE_BINARY] = "binary",
   [AST_WEBSOCKET_OPCODE_CLOSE] = "close",
   [AST_WEBSOCKET_OPCODE_PING] = "ping",
   [AST_WEBSOCKET_OPCODE_PONG] = "pong",
};

static const char *websocket_opcode2str(enum ast_websocket_opcode opcode)
{
   if (opcode < AST_WEBSOCKET_OPCODE_CONTINUATION ||
         opcode > AST_WEBSOCKET_OPCODE_PONG) {
      return "<unknown>";
   } else {
      return opcode_map[opcode];
   }
}

/*! \brief Write function for websocket traffic */
int AST_OPTIONAL_API_NAME(ast_websocket_write)(struct ast_websocket *session, enum ast_websocket_opcode opcode, char *payload, uint64_t payload_size)
{
   size_t header_size = 2; /* The minimum size of a websocket frame is 2 bytes */
   char *frame;
   uint64_t length;
   uint64_t frame_size;

   ast_debug(3, "Writing websocket %s frame, length %" PRIu64 "\n",
         websocket_opcode2str(opcode), payload_size);

   if (payload_size < 126) {
      length = payload_size;
   } else if (payload_size < (1 << 16)) {
      length = 126;
      /* We need an additional 2 bytes to store the extended length */
      header_size += 2;
   } else {
      length = 127;
      /* We need an additional 8 bytes to store the really really extended length */
      header_size += 8;
   }

   if (session->client) {
      /* Additional 4 bytes for the client masking key */
      header_size += 4;
   }

   frame_size = header_size + payload_size;

   frame = ast_alloca(frame_size + 1);
   memset(frame, 0, frame_size + 1);

   frame[0] = opcode | 0x80;
   frame[1] = length;

   /* Use the additional available bytes to store the length */
   if (length == 126) {
      put_unaligned_uint16(&frame[2], htons(payload_size));
   } else if (length == 127) {
      put_unaligned_uint64(&frame[2], htonll(payload_size));
   }

   memcpy(&frame[header_size], payload, payload_size);

   websocket_mask_payload(session, frame, &frame[header_size], payload_size);

   ao2_lock(session);
   if (session->closing) {
      ao2_unlock(session);
      return -1;
   }

   ast_iostream_set_timeout_sequence(session->stream, ast_tvnow(), session->timeout);
   if (ast_iostream_write(session->stream, frame, frame_size) != frame_size) {
      ao2_unlock(session);
      /* 1011 - server terminating connection due to not being able to fulfill the request */
      ast_debug(1, "Closing WS with 1011 because we can't fulfill a write request\n");
      ast_websocket_close(session, 1011);
      return -1;
   }

   ast_iostream_set_timeout_disable(session->stream);
   ao2_unlock(session);

   return 0;
}

void AST_OPTIONAL_API_NAME(ast_websocket_reconstruct_enable)(struct ast_websocket *session, size_t bytes)
{
   session->reconstruct = MIN(bytes, MAXIMUM_RECONSTRUCTION_CEILING);
}

void AST_OPTIONAL_API_NAME(ast_websocket_reconstruct_disable)(struct ast_websocket *session)
{
   session->reconstruct = 0;
}

void AST_OPTIONAL_API_NAME(ast_websocket_ref)(struct ast_websocket *session)
{
   ao2_ref(session, +1);
}

void AST_OPTIONAL_API_NAME(ast_websocket_unref)(struct ast_websocket *session)
{
   ao2_cleanup(session);
}

int AST_OPTIONAL_API_NAME(ast_websocket_fd)(struct ast_websocket *session)
{
   return session->closing ? -1 : ast_iostream_get_fd(session->stream);
}

int AST_OPTIONAL_API_NAME(ast_websocket_wait_for_input)(struct ast_websocket *session, int timeout)
{
   return session->closing ? -1 : ast_iostream_wait_for_input(session->stream, timeout);
}

struct ast_sockaddr * AST_OPTIONAL_API_NAME(ast_websocket_remote_address)(struct ast_websocket *session)
{
   return &session->remote_address;
}

struct ast_sockaddr * AST_OPTIONAL_API_NAME(ast_websocket_local_address)(struct ast_websocket *session)
{
   return &session->local_address;
}

int AST_OPTIONAL_API_NAME(ast_websocket_is_secure)(struct ast_websocket *session)
{
   return session->secure;
}

int AST_OPTIONAL_API_NAME(ast_websocket_set_nonblock)(struct ast_websocket *session)
{
   ast_iostream_nonblock(session->stream);
   ast_iostream_set_exclusive_input(session->stream, 0);
   return 0;
}

int AST_OPTIONAL_API_NAME(ast_websocket_set_timeout)(struct ast_websocket *session, int timeout)
{
   session->timeout = timeout;

   return 0;
}

const char * AST_OPTIONAL_API_NAME(ast_websocket_session_id)(struct ast_websocket *session)
{
   return session->session_id;
}


/* MAINTENANCE WARNING on ast_websocket_read()!
 *
 * We have to keep in mind during this function that the fact that session->fd seems ready
 * (via poll) does not necessarily mean we have application data ready, because in the case
 * of an SSL socket, there is some encryption data overhead that needs to be read from the
 * TCP socket, so poll() may say there are bytes to be read, but whether it is just 1 byte
 * or N bytes we do not know that, and we do not know how many of those bytes (if any) are
 * for application data (for us) and not just for the SSL protocol consumption
 *
 * There used to be a couple of nasty bugs here that were fixed in last refactoring but I
 * want to document them so the constraints are clear and we do not re-introduce them:
 *
 * - This function would incorrectly assume that fread() would necessarily return more than
 *   1 byte of data, just because a websocket frame is always >= 2 bytes, but the thing
 *   is we're dealing with a TCP bitstream here, we could read just one byte and that's normal.
 *   The problem before was that if just one byte was read, the function bailed out and returned
 *   an error, effectively dropping the first byte of a websocket frame header!
 *
 * - Another subtle bug was that it would just read up to MAX_WS_HDR_SZ (14 bytes) via fread()
 *   then assume that executing poll() would tell you if there is more to read, but since
 *   we're dealing with a buffered stream (session->f is a FILE*), poll would say there is
 *   nothing else to read (in the real tcp socket session->fd) and we would get stuck here
 *   without processing the rest of the data in session->f internal buffers until another packet
 *   came on the network to unblock us!
 *
 * Note during the header parsing stage we try to read in small chunks just what we need, this
 * is buffered data anyways, no expensive syscall required most of the time ...
 */
static inline int ws_safe_read(struct ast_websocket *session, char *buf, size_t len, enum ast_websocket_opcode *opcode)
{
   ssize_t rlen;
   int xlen = len;
   char *rbuf = buf;
   int sanity = 10;

   ast_assert(len > 0);

   if (!len) {
      errno = EINVAL;
      return -1;
   }

   ao2_lock(session);
   if (!session->stream) {
      ao2_unlock(session);
      errno = ECONNABORTED;
      return -1;
   }

   for (;;) {
      rlen = ast_iostream_read(session->stream, rbuf, xlen);
      if (rlen != xlen) {
         if (rlen == 0) {
            ast_log(LOG_WARNING, "Web socket closed abruptly\n");
            *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
            session->closing = 1;
            ao2_unlock(session);
            return -1;
         }

         if (rlen < 0 && errno != EAGAIN) {
            ast_log(LOG_ERROR, "Error reading from web socket: %s\n", strerror(errno));
            *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
            session->closing = 1;
            ao2_unlock(session);
            return -1;
         }

         if (!--sanity) {
            ast_log(LOG_WARNING, "Websocket seems unresponsive, disconnecting ...\n");
            *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
            session->closing = 1;
            ao2_unlock(session);
            return -1;
         }
      }
      if (rlen > 0) {
         xlen = xlen - rlen;
         rbuf = rbuf + rlen;
         if (!xlen) {
            break;
         }
      }
      if (ast_iostream_wait_for_input(session->stream, 1000) < 0) {
         ast_log(LOG_ERROR, "ast_iostream_wait_for_input returned err: %s\n", strerror(errno));
         *opcode = AST_WEBSOCKET_OPCODE_CLOSE;
         session->closing = 1;
         ao2_unlock(session);
         return -1;
      }
   }

   ao2_unlock(session);
   return 0;
}

int AST_OPTIONAL_API_NAME(ast_websocket_read)(struct ast_websocket *session, char **payload, uint64_t *payload_len, enum ast_websocket_opcode *opcode, int *fragmented)
{
   int fin = 0;
   int mask_present = 0;
   char *mask = NULL, *new_payload = NULL;
   size_t options_len = 0, frame_size = 0;

   *payload = NULL;
   *payload_len = 0;
   *fragmented = 0;

   if (ws_safe_read(session, &session->buf[0], MIN_WS_HDR_SZ, opcode)) {
      return -1;
   }
   frame_size += MIN_WS_HDR_SZ;

   /* ok, now we have the first 2 bytes, so we know some flags, opcode and payload length (or whether payload length extension will be required) */
   *opcode = session->buf[0] & 0xf;
   *payload_len = session->buf[1] & 0x7f;
   if (*opcode == AST_WEBSOCKET_OPCODE_TEXT || *opcode == AST_WEBSOCKET_OPCODE_BINARY || *opcode == AST_WEBSOCKET_OPCODE_CONTINUATION ||
       *opcode == AST_WEBSOCKET_OPCODE_PING || *opcode == AST_WEBSOCKET_OPCODE_PONG  || *opcode == AST_WEBSOCKET_OPCODE_CLOSE) {
      fin = (session->buf[0] >> 7) & 1;
      mask_present = (session->buf[1] >> 7) & 1;

      /* Based on the mask flag and payload length, determine how much more we need to read before start parsing the rest of the header */
      options_len += mask_present ? 4 : 0;
      options_len += (*payload_len == 126) ? 2 : (*payload_len == 127) ? 8 : 0;
      if (options_len) {
         /* read the rest of the header options */
         if (ws_safe_read(session, &session->buf[frame_size], options_len, opcode)) {
            return -1;
         }
         frame_size += options_len;
      }

      if (*payload_len == 126) {
         /* Grab the 2-byte payload length  */
         *payload_len = ntohs(get_unaligned_uint16(&session->buf[2]));
         mask = &session->buf[4];
      } else if (*payload_len == 127) {
         /* Grab the 8-byte payload length  */
         *payload_len = ntohll(get_unaligned_uint64(&session->buf[2]));
         mask = &session->buf[10];
      } else {
         /* Just set the mask after the small 2-byte header */
         mask = &session->buf[2];
      }

      /* Now read the rest of the payload */
      *payload = &session->buf[frame_size]; /* payload will start here, at the end of the options, if any */
      frame_size = frame_size + (*payload_len); /* final frame size is header + optional headers + payload data */
      if (frame_size > MAXIMUM_FRAME_SIZE) {
         ast_log(LOG_WARNING, "Cannot fit huge websocket frame of %zu bytes\n", frame_size);
         /* The frame won't fit :-( */
         ast_websocket_close(session, 1009);
         return -1;
      }

      if (*payload_len) {
         if (ws_safe_read(session, *payload, *payload_len, opcode)) {
            return -1;
         }
      }

      /* If a mask is present unmask the payload */
      if (mask_present) {
         unsigned int pos;
         for (pos = 0; pos < *payload_len; pos++) {
            (*payload)[pos] ^= mask[pos % 4];
         }
      }

      /* Per the RFC for PING we need to send back an opcode with the application data as received */
      if (*opcode == AST_WEBSOCKET_OPCODE_PING) {
         if (ast_websocket_write(session, AST_WEBSOCKET_OPCODE_PONG, *payload, *payload_len)) {
            ast_websocket_close(session, 1009);
         }
         *payload_len = 0;
         return 0;
      }

      /* Stop PONG processing here */
      if (*opcode == AST_WEBSOCKET_OPCODE_PONG) {
         *payload_len = 0;
         return 0;
      }

      /* Save the CLOSE status code which will be sent in our own CLOSE in the destructor */
      if (*opcode == AST_WEBSOCKET_OPCODE_CLOSE) {
         session->closing = 1;
         if (*payload_len >= 2) {
            session->close_status_code = ntohs(get_unaligned_uint16(*payload));
         }
         *payload_len = 0;
         return 0;
      }

      /* Below this point we are handling TEXT, BINARY or CONTINUATION opcodes */
      if (*payload_len) {
         if (!(new_payload = ast_realloc(session->payload, (session->payload_len + *payload_len)))) {
            ast_log(LOG_WARNING, "Failed allocation: %p, %zu, %"PRIu64"\n",
               session->payload, session->payload_len, *payload_len);
            *payload_len = 0;
            ast_websocket_close(session, 1009);
            return -1;
         }

         session->payload = new_payload;
         memcpy((session->payload + session->payload_len), (*payload), (*payload_len));
         session->payload_len += *payload_len;
      } else if (!session->payload_len && session->payload) {
         ast_free(session->payload);
         session->payload = NULL;
      }

      if (!fin && session->reconstruct && (session->payload_len < session->reconstruct)) {
         /* If this is not a final message we need to defer returning it until later */
         if (*opcode != AST_WEBSOCKET_OPCODE_CONTINUATION) {
            session->opcode = *opcode;
         }
         *opcode = AST_WEBSOCKET_OPCODE_CONTINUATION;
         *payload_len = 0;
         *payload = NULL;
      } else {
         if (*opcode == AST_WEBSOCKET_OPCODE_CONTINUATION) {
            if (!fin) {
               /* If this was not actually the final message tell the user it is fragmented so they can deal with it accordingly */
               *fragmented = 1;
            } else {
               /* Final frame in multi-frame so push up the actual opcode */
               *opcode = session->opcode;
            }
         }
         *payload_len = session->payload_len;
         *payload = session->payload;
         session->payload_len = 0;
      }
   } else {
      ast_log(LOG_WARNING, "WebSocket unknown opcode %u\n", *opcode);
      /* We received an opcode that we don't understand, the RFC states that 1003 is for a type of data that can't be accepted... opcodes
       * fit that, I think. */
      ast_websocket_close(session, 1003);
   }

   return 0;
}

/*!
 * \brief If the server has exactly one configured protocol, return it.
 */
static struct ast_websocket_protocol *one_protocol(
   struct ast_websocket_server *server)
{
   SCOPED_AO2LOCK(lock, server->protocols);

   if (ao2_container_count(server->protocols) != 1) {
      return NULL;
   }

   return ao2_callback(server->protocols, OBJ_NOLOCK, NULL, NULL);
}

static char *websocket_combine_key(const char *key, char *res, int res_size)
{
   char *combined;
   unsigned combined_length = strlen(key) + strlen(WEBSOCKET_GUID) + 1;
   uint8_t sha[20];

   combined = ast_alloca(combined_length);
   snprintf(combined, combined_length, "%s%s", key, WEBSOCKET_GUID);
   ast_sha1_hash_uint(sha, combined);
   ast_base64encode(res, (const unsigned char*)sha, 20, res_size);
   return res;
}

static void websocket_bad_request(struct ast_tcptls_session_instance *ser)
{
   struct ast_str *http_header = ast_str_create(64);

   if (!http_header) {
      ast_http_request_close_on_completion(ser);
      ast_http_error(ser, 500, "Server Error", "Out of memory");
      return;
   }
   ast_str_set(&http_header, 0, "Sec-WebSocket-Version: 7, 8, 13\r\n");
   ast_http_send(ser, AST_HTTP_UNKNOWN, 400, "Bad Request", http_header, NULL, 0, 0);
}

int AST_OPTIONAL_API_NAME(ast_websocket_uri_cb)(struct ast_tcptls_session_instance *ser, const struct ast_http_uri *urih, const char *uri, enum ast_http_method method, struct ast_variable *get_vars, struct ast_variable *headers)
{
   struct ast_variable *v;
   const char *upgrade = NULL, *key = NULL, *key1 = NULL, *key2 = NULL, *protos = NULL;
   char *requested_protocols = NULL, *protocol = NULL;
   int version = 0, flags = 1;
   struct ast_websocket_protocol *protocol_handler = NULL;
   struct ast_websocket *session;
   struct ast_websocket_server *server;

   SCOPED_MODULE_USE(ast_module_info->self);

   /* Upgrade requests are only permitted on GET methods */
   if (method != AST_HTTP_GET) {
      ast_http_error(ser, 501, "Not Implemented", "Attempt to use unimplemented / unsupported method");
      return 0;
   }

   server = urih->data;

   /* Get the minimum headers required to satisfy our needs */
   for (v = headers; v; v = v->next) {
      if (!strcasecmp(v->name, "Upgrade")) {
         upgrade = v->value;
      } else if (!strcasecmp(v->name, "Sec-WebSocket-Key")) {
         key = v->value;
      } else if (!strcasecmp(v->name, "Sec-WebSocket-Key1")) {
         key1 = v->value;
      } else if (!strcasecmp(v->name, "Sec-WebSocket-Key2")) {
         key2 = v->value;
      } else if (!strcasecmp(v->name, "Sec-WebSocket-Protocol")) {
         protos = v->value;
      } else if (!strcasecmp(v->name, "Sec-WebSocket-Version")) {
         if (sscanf(v->value, "%30d", &version) != 1) {
            version = 0;
         }
      }
   }

   /* If this is not a websocket upgrade abort */
   if (!upgrade || strcasecmp(upgrade, "websocket")) {
      ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - did not request WebSocket\n",
         ast_sockaddr_stringify(&ser->remote_address));
      ast_http_error(ser, 426, "Upgrade Required", NULL);
      return 0;
   } else if (ast_strlen_zero(protos)) {
      /* If there's only a single protocol registered, and the
       * client doesn't specify what protocol it's using, go ahead
       * and accept the connection */
      protocol_handler = one_protocol(server);
      if (!protocol_handler) {
         /* Multiple registered subprotocols; client must specify */
         ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - no protocols requested\n",
            ast_sockaddr_stringify(&ser->remote_address));
         websocket_bad_request(ser);
         return 0;
      }
   } else if (key1 && key2) {
      /* Specification defined in http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-76 and
       * http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-00 -- not currently supported*/
      ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - unsupported version '00/76' chosen\n",
         ast_sockaddr_stringify(&ser->remote_address));
      websocket_bad_request(ser);
      return 0;
   }

   if (!protocol_handler && protos) {
      requested_protocols = ast_strdupa(protos);
      /* Iterate through the requested protocols trying to find one that we have a handler for */
      while (!protocol_handler && (protocol = strsep(&requested_protocols, ","))) {
         protocol_handler = ao2_find(server->protocols, ast_strip(protocol), OBJ_KEY);
      }
   }

   /* If no protocol handler exists bump this back to the requester */
   if (!protocol_handler) {
      ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - no protocols out of '%s' supported\n",
         ast_sockaddr_stringify(&ser->remote_address), protos);
      websocket_bad_request(ser);
      return 0;
   }

   /* Determine how to respond depending on the version */
   if (version == 7 || version == 8 || version == 13) {
      char base64[64];

      if (!key || strlen(key) + strlen(WEBSOCKET_GUID) + 1 > 8192) { /* no stack overflows please */
         websocket_bad_request(ser);
         ao2_ref(protocol_handler, -1);
         return 0;
      }

      if (ast_http_body_discard(ser)) {
         websocket_bad_request(ser);
         ao2_ref(protocol_handler, -1);
         return 0;
      }

      if (!(session = ao2_alloc(sizeof(*session) + AST_UUID_STR_LEN + 1, session_destroy_fn))) {
         ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted\n",
            ast_sockaddr_stringify(&ser->remote_address));
         websocket_bad_request(ser);
         ao2_ref(protocol_handler, -1);
         return 0;
      }
      session->timeout = AST_DEFAULT_WEBSOCKET_WRITE_TIMEOUT;

      /* Generate the session id */
      if (!ast_uuid_generate_str(session->session_id, sizeof(session->session_id))) {
         ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - failed to generate a session id\n",
            ast_sockaddr_stringify(&ser->remote_address));
         ast_http_error(ser, 500, "Internal Server Error", "Allocation failed");
         ao2_ref(protocol_handler, -1);
         return 0;
      }

      if (protocol_handler->session_attempted
          && protocol_handler->session_attempted(ser, get_vars, headers, session->session_id)) {
         ast_debug(3, "WebSocket connection from '%s' rejected by protocol handler '%s'\n",
            ast_sockaddr_stringify(&ser->remote_address), protocol_handler->name);
         websocket_bad_request(ser);
         ao2_ref(protocol_handler, -1);
         return 0;
      }

      /* RFC 6455, Section 4.1:
       *
       * 6. If the response includes a |Sec-WebSocket-Protocol| header
       *    field and this header field indicates the use of a
       *    subprotocol that was not present in the client's handshake
       *    (the server has indicated a subprotocol not requested by
       *    the client), the client MUST _Fail the WebSocket
       *    Connection_.
       */
      if (protocol) {
         ast_iostream_printf(ser->stream,
            "HTTP/1.1 101 Switching Protocols\r\n"
            "Upgrade: %s\r\n"
            "Connection: Upgrade\r\n"
            "Sec-WebSocket-Accept: %s\r\n"
            "Sec-WebSocket-Protocol: %s\r\n\r\n",
            upgrade,
            websocket_combine_key(key, base64, sizeof(base64)),
            protocol);
      } else {
         ast_iostream_printf(ser->stream,
            "HTTP/1.1 101 Switching Protocols\r\n"
            "Upgrade: %s\r\n"
            "Connection: Upgrade\r\n"
            "Sec-WebSocket-Accept: %s\r\n\r\n",
            upgrade,
            websocket_combine_key(key, base64, sizeof(base64)));
      }
   } else {

      /* Specification defined in http://tools.ietf.org/html/draft-hixie-thewebsocketprotocol-75 or completely unknown */
      ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - unsupported version '%d' chosen\n",
         ast_sockaddr_stringify(&ser->remote_address), version ? version : 75);
      websocket_bad_request(ser);
      ao2_ref(protocol_handler, -1);
      return 0;
   }

   /* Enable keepalive on all sessions so the underlying user does not have to */
   if (setsockopt(ast_iostream_get_fd(ser->stream), SOL_SOCKET, SO_KEEPALIVE, &flags, sizeof(flags))) {
      ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - failed to enable keepalive\n",
         ast_sockaddr_stringify(&ser->remote_address));
      websocket_bad_request(ser);
      ao2_ref(session, -1);
      ao2_ref(protocol_handler, -1);
      return 0;
   }

   /* Get our local address for the connected socket */
   if (ast_getsockname(ast_iostream_get_fd(ser->stream), &session->local_address)) {
      ast_log(LOG_WARNING, "WebSocket connection from '%s' could not be accepted - failed to get local address\n",
         ast_sockaddr_stringify(&ser->remote_address));
      websocket_bad_request(ser);
      ao2_ref(session, -1);
      ao2_ref(protocol_handler, -1);
      return 0;
   }

   ast_verb(2, "WebSocket connection from '%s' for protocol '%s' accepted using version '%d'\n", ast_sockaddr_stringify(&ser->remote_address), protocol ? : "", version);

   /* Populate the session with all the needed details */
   session->stream = ser->stream;
   ast_sockaddr_copy(&session->remote_address, &ser->remote_address);
   session->opcode = -1;
   session->reconstruct = DEFAULT_RECONSTRUCTION_CEILING;
   session->secure = ast_iostream_get_ssl(ser->stream) ? 1 : 0;

   /* Give up ownership of the socket and pass it to the protocol handler */
   ast_iostream_set_exclusive_input(session->stream, 0);
   protocol_handler->session_established(session, get_vars, headers);
   ao2_ref(protocol_handler, -1);

   /*
    * By dropping the stream from the session the connection
    * won't get closed when the HTTP server cleans up because we
    * passed the connection to the protocol handler.
    */
   ser->stream = NULL;

   return 0;
}

static struct ast_http_uri websocketuri = {
   .callback = AST_OPTIONAL_API_NAME(ast_websocket_uri_cb),
   .description = "Asterisk HTTP WebSocket",
   .uri = "ws",
   .has_subtree = 0,
   .data = NULL,
   .key = __FILE__,
};

/*! \brief Simple echo implementation which echoes received text and binary frames */
static void websocket_echo_callback(struct ast_websocket *session, struct ast_variable *parameters, struct ast_variable *headers)
{
   int res;

   ast_debug(1, "Entering WebSocket echo loop\n");

   if (ast_fd_set_flags(ast_websocket_fd(session), O_NONBLOCK)) {
      goto end;
   }

   while ((res = ast_websocket_wait_for_input(session, -1)) > 0) {
      char *payload;
      uint64_t payload_len;
      enum ast_websocket_opcode opcode;
      int fragmented;

      if (ast_websocket_read(session, &payload, &payload_len, &opcode, &fragmented)) {
         /* We err on the side of caution and terminate the session if any error occurs */
         ast_log(LOG_WARNING, "Read failure during WebSocket echo loop\n");
         break;
      }

      if (opcode == AST_WEBSOCKET_OPCODE_TEXT || opcode == AST_WEBSOCKET_OPCODE_BINARY) {
         ast_websocket_write(session, opcode, payload, payload_len);
      } else if (opcode == AST_WEBSOCKET_OPCODE_CLOSE) {
         break;
      } else {
         ast_debug(1, "Ignored WebSocket opcode %u\n", opcode);
      }
   }

end:
   ast_debug(1, "Exiting WebSocket echo loop\n");
   ast_websocket_unref(session);
}

static int websocket_add_protocol_internal(const char *name, ast_websocket_callback callback)
{
   struct ast_websocket_server *ws_server = websocketuri.data;
   if (!ws_server) {
      return -1;
   }
   return ast_websocket_server_add_protocol(ws_server, name, callback);
}

int AST_OPTIONAL_API_NAME(ast_websocket_add_protocol)(const char *name, ast_websocket_callback callback)
{
   return websocket_add_protocol_internal(name, callback);
}

int AST_OPTIONAL_API_NAME(ast_websocket_add_protocol2)(struct ast_websocket_protocol *protocol)
{
   struct ast_websocket_server *ws_server = websocketuri.data;

   if (!ws_server) {
      return -1;
   }

   if (ast_websocket_server_add_protocol2(ws_server, protocol)) {
      return -1;
   }

   return 0;
}

static int websocket_remove_protocol_internal(const char *name, ast_websocket_callback callback)
{
   struct ast_websocket_server *ws_server = websocketuri.data;
   if (!ws_server) {
      return -1;
   }
   return ast_websocket_server_remove_protocol(ws_server, name, callback);
}

int AST_OPTIONAL_API_NAME(ast_websocket_remove_protocol)(const char *name, ast_websocket_callback callback)
{
   return websocket_remove_protocol_internal(name, callback);
}

/*! \brief Parse the given uri into a path and remote address.
 *
 * Expected uri form: [ws[s]]://<host>[:port][/<path>]
 *
 * The returned host will contain the address and optional port while
 * path will contain everything after the address/port if included.
 */
static int websocket_client_parse_uri(const char *uri, char **host, struct ast_str **path)
{
   struct ast_uri *parsed_uri = ast_uri_parse_websocket(uri);

   if (!parsed_uri) {
      return -1;
   }

   *host = ast_uri_make_host_with_port(parsed_uri);

   if (ast_uri_path(parsed_uri) || ast_uri_query(parsed_uri)) {
      *path = ast_str_create(64);
      if (!*path) {
         ao2_ref(parsed_uri, -1);
         return -1;
      }

      if (ast_uri_path(parsed_uri)) {
         ast_str_set(path, 0, "%s", ast_uri_path(parsed_uri));
      }

      if (ast_uri_query(parsed_uri)) {
         ast_str_append(path, 0, "?%s", ast_uri_query(parsed_uri));
      }
   }

   ao2_ref(parsed_uri, -1);
   return 0;
}

static void websocket_client_args_destroy(void *obj)
{
   struct ast_tcptls_session_args *args = obj;

   if (args->tls_cfg) {
      ast_free(args->tls_cfg->certfile);
      ast_free(args->tls_cfg->pvtfile);
      ast_free(args->tls_cfg->cipher);
      ast_free(args->tls_cfg->cafile);
      ast_free(args->tls_cfg->capath);

      ast_ssl_teardown(args->tls_cfg);
   }
   ast_free(args->tls_cfg);
}

static struct ast_tcptls_session_args *websocket_client_args_create(
   const char *host, struct ast_tls_config *tls_cfg,
   enum ast_websocket_result *result)
{
   struct ast_sockaddr *addr;
   struct ast_tcptls_session_args *args = ao2_alloc(
      sizeof(*args), websocket_client_args_destroy);

   if (!args) {
      *result = WS_ALLOCATE_ERROR;
      return NULL;
   }

   args->accept_fd = -1;
   args->tls_cfg = tls_cfg;
   args->name = "websocket client";

   if (!ast_sockaddr_resolve(&addr, host, 0, 0)) {
      ast_log(LOG_ERROR, "Unable to resolve address %s\n",
         host);
      ao2_ref(args, -1);
      *result = WS_URI_RESOLVE_ERROR;
      return NULL;
   }
   ast_sockaddr_copy(&args->remote_address, addr);
   ast_free(addr);
   return args;
}

static char *websocket_client_create_key(void)
{
   static int encoded_size = CLIENT_KEY_SIZE * 2 * sizeof(char) + 1;
   /* key is randomly selected 16-byte base64 encoded value */
   unsigned char key[CLIENT_KEY_SIZE + sizeof(long) - 1];
   char *encoded = ast_malloc(encoded_size);
   long i = 0;

   if (!encoded) {
      ast_log(LOG_ERROR, "Unable to allocate client websocket key\n");
      return NULL;
   }

   while (i < CLIENT_KEY_SIZE) {
      long num = ast_random();
      memcpy(key + i, &num, sizeof(long));
      i += sizeof(long);
   }

   ast_base64encode(encoded, key, CLIENT_KEY_SIZE, encoded_size);
   return encoded;
}

struct websocket_client {
   /*! host portion of client uri */
   char *host;
   /*! path for logical websocket connection */
   struct ast_str *resource_name;
   /*! unique key used during server handshaking */
   char *key;
   /*! container for registered protocols */
   char *protocols;
   /*! the protocol accepted by the server */
   char *accept_protocol;
   /*! websocket protocol version */
   int version;
   /*! tcptls connection arguments */
   struct ast_tcptls_session_args *args;
   /*! tcptls connection instance */
   struct ast_tcptls_session_instance *ser;
};

static void websocket_client_destroy(void *obj)
{
   struct websocket_client *client = obj;

   ao2_cleanup(client->ser);
   ao2_cleanup(client->args);

   ast_free(client->accept_protocol);
   ast_free(client->protocols);
   ast_free(client->key);
   ast_free(client->resource_name);
   ast_free(client->host);
}

static struct ast_websocket * websocket_client_create(
   const char *uri, const char *protocols,   struct ast_tls_config *tls_cfg,
   enum ast_websocket_result *result)
{
   struct ast_websocket *ws = ao2_alloc(sizeof(*ws), session_destroy_fn);

   if (!ws) {
      ast_log(LOG_ERROR, "Unable to allocate websocket\n");
      *result = WS_ALLOCATE_ERROR;
      return NULL;
   }

   if (!(ws->client = ao2_alloc(
            sizeof(*ws->client), websocket_client_destroy))) {
      ast_log(LOG_ERROR, "Unable to allocate websocket client\n");
      *result = WS_ALLOCATE_ERROR;
      return NULL;
   }

   if (!(ws->client->key = websocket_client_create_key())) {
      ao2_ref(ws, -1);
      *result = WS_KEY_ERROR;
      return NULL;
   }

   if (websocket_client_parse_uri(
          uri, &ws->client->host, &ws->client->resource_name)) {
      ao2_ref(ws, -1);
      *result = WS_URI_PARSE_ERROR;
      return NULL;
   }

   if (!(ws->client->args = websocket_client_args_create(
            ws->client->host, tls_cfg, result))) {
      ao2_ref(ws, -1);
      return NULL;
   }
   ws->client->protocols = ast_strdup(protocols);

   ws->client->version = 13;
   ws->opcode = -1;
   ws->reconstruct = DEFAULT_RECONSTRUCTION_CEILING;
   return ws;
}

const char * AST_OPTIONAL_API_NAME(
   ast_websocket_client_accept_protocol)(struct ast_websocket *ws)
{
   return ws->client->accept_protocol;
}

static enum ast_websocket_result websocket_client_handle_response_code(
   struct websocket_client *client, int response_code)
{
   if (response_code <= 0) {
      return WS_INVALID_RESPONSE;
   }

   switch (response_code) {
   case 101:
      return 0;
   case 400:
      ast_log(LOG_ERROR, "Received response 400 - Bad Request "
         "- from %s\n", client->host);
      return WS_BAD_REQUEST;
   case 404:
      ast_log(LOG_ERROR, "Received response 404 - Request URL not "
         "found - from %s\n", client->host);
      return WS_URL_NOT_FOUND;
   }

   ast_log(LOG_ERROR, "Invalid HTTP response code %d from %s\n",
      response_code, client->host);
   return WS_INVALID_RESPONSE;
}

static enum ast_websocket_result websocket_client_handshake_get_response(
   struct websocket_client *client)
{
   enum ast_websocket_result res;
   char buf[4096];
   char base64[64];
   int has_upgrade = 0;
   int has_connection = 0;
   int has_accept = 0;
   int has_protocol = 0;

   if (ast_iostream_gets(client->ser->stream, buf, sizeof(buf)) <= 0) {
      ast_log(LOG_ERROR, "Unable to retrieve HTTP status line.");
      return WS_BAD_STATUS;
   }

   if ((res = websocket_client_handle_response_code(client,
          ast_http_response_status_line(
             buf, "HTTP/1.1", 101))) != WS_OK) {
      return res;
   }

   /* Ignoring line folding - assuming header field values are contained
      within a single line */
   while (ast_iostream_gets(client->ser->stream, buf, sizeof(buf)) > 0) {
      char *name, *value;
      int parsed = ast_http_header_parse(buf, &name, &value);

      if (parsed < 0) {
         break;
      }

      if (parsed > 0) {
         continue;
      }

      if (!has_upgrade &&
          (has_upgrade = ast_http_header_match(
             name, "upgrade", value, "websocket")) < 0) {
         return WS_HEADER_MISMATCH;
      } else if (!has_connection &&
            (has_connection = ast_http_header_match(
               name, "connection", value, "upgrade")) < 0) {
         return WS_HEADER_MISMATCH;
      } else if (!has_accept &&
            (has_accept = ast_http_header_match(
               name, "sec-websocket-accept", value,
             websocket_combine_key(
                client->key, base64, sizeof(base64)))) < 0) {
         return WS_HEADER_MISMATCH;
      } else if (!has_protocol &&
            (has_protocol = ast_http_header_match_in(
               name, "sec-websocket-protocol", value, client->protocols))) {
         if (has_protocol < 0) {
            return WS_HEADER_MISMATCH;
         }
         client->accept_protocol = ast_strdup(value);
      } else if (!strcasecmp(name, "sec-websocket-extensions")) {
         ast_log(LOG_ERROR, "Extensions received, but not "
            "supported by client\n");
         return WS_NOT_SUPPORTED;
      }
   }
   return has_upgrade && has_connection && has_accept ?
      WS_OK : WS_HEADER_MISSING;
}

static enum ast_websocket_result websocket_client_handshake(
   struct websocket_client *client)
{
   char protocols[100] = "";

   if (!ast_strlen_zero(client->protocols)) {
      sprintf(protocols, "Sec-WebSocket-Protocol: %s\r\n",
         client->protocols);
   }

   if (ast_iostream_printf(client->ser->stream,
         "GET /%s HTTP/1.1\r\n"
         "Sec-WebSocket-Version: %d\r\n"
         "Upgrade: websocket\r\n"
         "Connection: Upgrade\r\n"
         "Host: %s\r\n"
         "Sec-WebSocket-Key: %s\r\n"
         "%s\r\n",
         client->resource_name ? ast_str_buffer(client->resource_name) : "",
         client->version,
         client->host,
         client->key,
         protocols) < 0) {
      ast_log(LOG_ERROR, "Failed to send handshake.\n");
      return WS_WRITE_ERROR;
   }
   /* wait for a response before doing anything else */
   return websocket_client_handshake_get_response(client);
}

static enum ast_websocket_result websocket_client_connect(struct ast_websocket *ws)
{
   enum ast_websocket_result res;
   /* create and connect the client - note client_start
      releases the session instance on failure */
   if (!(ws->client->ser = ast_tcptls_client_start(
            ast_tcptls_client_create(ws->client->args)))) {
      return WS_CLIENT_START_ERROR;
   }

   if ((res = websocket_client_handshake(ws->client)) != WS_OK) {
      ao2_ref(ws->client->ser, -1);
      ws->client->ser = NULL;
      return res;
   }

   ws->stream = ws->client->ser->stream;
   ws->secure = ast_iostream_get_ssl(ws->stream) ? 1 : 0;
   ws->client->ser->stream = NULL;
   ast_sockaddr_copy(&ws->remote_address, &ws->client->ser->remote_address);
   return WS_OK;
}

struct ast_websocket *AST_OPTIONAL_API_NAME(ast_websocket_client_create)
   (const char *uri, const char *protocols, struct ast_tls_config *tls_cfg,
    enum ast_websocket_result *result)
{
   struct ast_websocket *ws = websocket_client_create(
      uri, protocols, tls_cfg, result);

   if (!ws) {
      return NULL;
   }

   if ((*result = websocket_client_connect(ws)) != WS_OK) {
      ao2_ref(ws, -1);
      return NULL;
   }

   return ws;
}

int AST_OPTIONAL_API_NAME(ast_websocket_read_string)
   (struct ast_websocket *ws, char **buf)
{
   char *payload;
   uint64_t payload_len;
   enum ast_websocket_opcode opcode;
   int fragmented = 1;

   while (fragmented) {
      if (ast_websocket_read(ws, &payload, &payload_len,
                   &opcode, &fragmented)) {
         ast_log(LOG_ERROR, "Client WebSocket string read - "
            "error reading string data\n");
         return -1;
      }

      if (opcode == AST_WEBSOCKET_OPCODE_PING) {
         /* Try read again, we have sent pong already */
         fragmented = 1;
         continue;
      }

      if (opcode == AST_WEBSOCKET_OPCODE_CONTINUATION) {
         continue;
      }

      if (opcode == AST_WEBSOCKET_OPCODE_CLOSE) {
         return -1;
      }

      if (opcode != AST_WEBSOCKET_OPCODE_TEXT) {
         ast_log(LOG_ERROR, "Client WebSocket string read - "
            "non string data received\n");
         return -1;
      }
   }

   if (!(*buf = ast_strndup(payload, payload_len))) {
      return -1;
   }

   return payload_len + 1;
}

int AST_OPTIONAL_API_NAME(ast_websocket_write_string)
   (struct ast_websocket *ws, const char *buf)
{
   uint64_t len = strlen(buf);

   ast_debug(3, "Writing websocket string of length %" PRIu64 "\n", len);

   /* We do not pass strlen(buf) to ast_websocket_write() directly because the
    * size_t returned by strlen() may not require the same storage size
    * as the uint64_t that ast_websocket_write() uses. This normally
    * would not cause a problem, but since ast_websocket_write() uses
    * the optional API, this function call goes through a series of macros
    * that may cause a 32-bit to 64-bit conversion to go awry.
    */
   return ast_websocket_write(ws, AST_WEBSOCKET_OPCODE_TEXT,
               (char *)buf, len);
}

static int load_module(void)
{
   websocketuri.data = websocket_server_internal_create();
   if (!websocketuri.data) {
      return AST_MODULE_LOAD_DECLINE;
   }
   ast_http_uri_link(&websocketuri);
   websocket_add_protocol_internal("echo", websocket_echo_callback);

   return 0;
}

static int unload_module(void)
{
   websocket_remove_protocol_internal("echo", websocket_echo_callback);
   ast_http_uri_unlink(&websocketuri);
   ao2_ref(websocketuri.data, -1);
   websocketuri.data = NULL;

   return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "HTTP WebSocket Support",
   .support_level = AST_MODULE_SUPPORT_CORE,
   .load = load_module,
   .unload = unload_module,
   .load_pri = AST_MODPRI_CHANNEL_DEPEND,
   .requires = "http",
);