res_http_websocket.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 2012, Digium, Inc.
 *
 * Joshua Colp <jcolp@digium.com>
 *
 * 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 <jcolp@digium.com>
 */
 
/*** 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 Default reconstruction size for multi-frame payload reconstruction. If exceeded the next frame will start a
 *         payload.
 */
#define DEFAULT_RECONSTRUCTION_CEILING AST_WEBSOCKET_MAX_RX_PAYLOAD_SIZE
 
/*! \brief Maximum reconstruction size for multi-frame payload reconstruction. */
#define MAXIMUM_RECONSTRUCTION_CEILING AST_WEBSOCKET_MAX_RX_PAYLOAD_SIZE
#else
/*! \brief Default reconstruction size for multi-frame payload reconstruction. If exceeded the next frame will start a
 *         payload.
 */
#define DEFAULT_RECONSTRUCTION_CEILING AST_WEBSOCKET_MAX_RX_PAYLOAD_SIZE
 
/*! \brief Maximum reconstruction size for multi-frame payload reconstruction. */
#define MAXIMUM_RECONSTRUCTION_CEILING AST_WEBSOCKET_MAX_RX_PAYLOAD_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[AST_WEBSOCKET_MAX_RX_PAYLOAD_SIZE];        /*!< Fixed buffer for reading data into */
};
 
const char *ast_websocket_type_to_str(enum ast_websocket_type type)
{
    switch (type) {
    case AST_WS_TYPE_CLIENT_PERSISTENT:
        return "persistent";
    case AST_WS_TYPE_CLIENT_PER_CALL:
        return "per_call";
    case AST_WS_TYPE_CLIENT_PER_CALL_CONFIG:
        return "per_call_config";
    case AST_WS_TYPE_CLIENT:
        return "client";
    case AST_WS_TYPE_INBOUND:
        return "inbound";
    case AST_WS_TYPE_SERVER:
        return "server";
    case AST_WS_TYPE_ANY:
        return "any";
    default:
        return "unknown";
    }
}
 
/*! \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_debug(3, "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_debug(1, "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_debug(1, "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 > AST_WEBSOCKET_MAX_RX_PAYLOAD_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_debug(3, "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:
 * \verbatim [ws[s]]://<host>[:port][/<path>] \endverbatim
 *
 * 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, char **userinfo)
{
    struct ast_uri *parsed_uri = ast_uri_parse_websocket(uri);
 
    if (!parsed_uri) {
        return -1;
    }
 
    *host = ast_uri_make_host_with_port(parsed_uri);
    *userinfo = ast_strdup(ast_uri_user_info(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);
 
    /* We need to save off the hostname but it may contain a port spec */
    snprintf(args->hostname, sizeof(args->hostname),
        "%.*s",
        (int) strcspn(host, ":"), host);
 
    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;
    /*! Authentication userid:password */
    char *userinfo;
    /*! Suppress connection log messages */
    int suppress_connection_msgs;
};
 
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);
    ast_free(client->userinfo);
}
 
static struct ast_websocket * websocket_client_create(
    struct ast_websocket_client_options *options, 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 (!ast_uuid_generate_str(ws->session_id, sizeof(ws->session_id))) {
        ast_log(LOG_ERROR, "Unable to allocate websocket session_id\n");
        ao2_ref(ws, -1);
        *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");
        ao2_ref(ws, -1);
        *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(
            options->uri, &ws->client->host, &ws->client->resource_name,
            &ws->client->userinfo)) {
        ao2_ref(ws, -1);
        *result = WS_URI_PARSE_ERROR;
        return NULL;
    }
 
    if (ast_strlen_zero(ws->client->userinfo)
        && !ast_strlen_zero(options->username)
        && !ast_strlen_zero(options->password)) {
        ast_asprintf(&ws->client->userinfo, "%s:%s", options->username,
            options->password);
    }
 
    if (!(ws->client->args = websocket_client_args_create(
              ws->client->host, options->tls_cfg, result))) {
        ao2_ref(ws, -1);
        return NULL;
    }
 
    ws->client->suppress_connection_msgs = options->suppress_connection_msgs;
    ws->client->args->suppress_connection_msgs = options->suppress_connection_msgs;
    ws->client->protocols = ast_strdup(options->protocols);
    ws->client->version = 13;
    ws->opcode = -1;
    ws->reconstruct = DEFAULT_RECONSTRUCTION_CEILING;
    ws->timeout = options->timeout;
 
    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:
        if (!client->suppress_connection_msgs) {
            ast_log(LOG_ERROR, "Received response 400 - Bad Request "
                "- from %s\n", client->host);
        }
        return WS_BAD_REQUEST;
    case 401:
        if (!client->suppress_connection_msgs) {
            ast_log(LOG_ERROR, "Received response 401 - Unauthorized "
                "- from %s\n", client->host);
        }
        return WS_UNAUTHORIZED;
    case 404:
        if (!client->suppress_connection_msgs) {
            ast_log(LOG_ERROR, "Received response 404 - Request URL not "
                "found - from %s\n", client->host);
        }
        return WS_URL_NOT_FOUND;
    }
 
    if (!client->suppress_connection_msgs) {
        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;
 
    while (ast_iostream_gets(client->ser->stream, buf, sizeof(buf)) <= 0) {
        if (errno == EINTR || errno == EAGAIN) {
            continue;
        }
 
        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 (1) {
        ssize_t len = ast_iostream_gets(client->ser->stream, buf, sizeof(buf));
        char *name, *value;
        int parsed;
 
        if (len <= 0) {
            if (errno == EINTR || errno == EAGAIN) {
                continue;
            }
            break;
        }
 
        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;
}
 
#define optional_header_spec "%s%s%s"
#define print_optional_header(test, name, value) \
    test ? name : "", \
    test ? value : "", \
    test ? "\r\n" : ""
 
static enum ast_websocket_result websocket_client_handshake(
    struct websocket_client *client)
{
    size_t protocols_len = 0;
    struct ast_variable *auth_header = NULL;
    size_t res;
 
    if (!ast_strlen_zero(client->userinfo)) {
        auth_header = ast_http_create_basic_auth_header(client->userinfo, NULL);
        if (!auth_header) {
            ast_log(LOG_ERROR, "Unable to allocate client websocket userinfo\n");
            return WS_ALLOCATE_ERROR;
        }
    }
 
    protocols_len = client->protocols ? strlen(client->protocols) : 0;
 
    res = 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"
        optional_header_spec
        optional_header_spec
        "Sec-WebSocket-Key: %s\r\n"
        "\r\n",
        client->resource_name ? ast_str_buffer(client->resource_name) : "",
        client->version,
        client->host,
        print_optional_header(auth_header, "Authorization: ", auth_header->value),
        print_optional_header(protocols_len, "Sec-WebSocket-Protocol: ", client->protocols),
        client->key
    );
 
    ast_variables_destroy(auth_header);
    if (res < 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, int timeout)
{
    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_timeout(
              ast_tcptls_client_create(ws->client->args), timeout))) {
        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_client_options options = {
        .uri = uri,
        .protocols = protocols,
        .timeout = -1,
        .tls_cfg = tls_cfg,
    };
 
    return ast_websocket_client_create_with_options(&options, result);
}
 
struct ast_websocket *AST_OPTIONAL_API_NAME(ast_websocket_client_create_with_options)
    (struct ast_websocket_client_options *options, enum ast_websocket_result *result)
{
    struct ast_websocket *ws = websocket_client_create(options, result);
 
    if (!ws) {
        return NULL;
    }
 
    if ((*result = websocket_client_connect(ws, options->timeout)) != 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);
}
 
const char *websocket_result_string_map[] = {
    [WS_OK] = "OK",
    [WS_ALLOCATE_ERROR] = "Allocation error",
    [WS_KEY_ERROR] = "Key error",
    [WS_URI_PARSE_ERROR] = "URI parse error",
    [WS_URI_RESOLVE_ERROR] = "URI resolve error",
    [WS_BAD_STATUS] = "Bad status line",
    [WS_INVALID_RESPONSE] = "Invalid response code",
    [WS_BAD_REQUEST] = "Bad request",
    [WS_URL_NOT_FOUND] = "URL not found",
    [WS_HEADER_MISMATCH] = "Header mismatch",
    [WS_HEADER_MISSING] = "Header missing",
    [WS_NOT_SUPPORTED] = "Not supported",
    [WS_WRITE_ERROR] = "Write error",
    [WS_CLIENT_START_ERROR] = "Client start error",
    [WS_UNAUTHORIZED] = "Unauthorized"
};
 
const char *AST_OPTIONAL_API_NAME(ast_websocket_result_to_str)
    (enum ast_websocket_result result)
{
    if (!ARRAY_IN_BOUNDS(result, websocket_result_string_map)) {
        return "unknown";
    }
    return websocket_result_string_map[result];
}
 
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",
);