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qemu/ui/vnc-ws.c

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/*
* QEMU VNC display driver: Websockets support
*
* Copyright (C) 2010 Joel Martin
* Copyright (C) 2012 Tim Hardeck
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; if not, see <http://www.gnu.org/licenses/>.
*/
#include "vnc.h"
void vncws_handshake_read(void *opaque)
{
VncState *vs = opaque;
uint8_t *handshake_end;
long ret;
buffer_reserve(&vs->ws_input, 4096);
ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), 4096);
if (!ret) {
if (vs->csock == -1) {
vnc_disconnect_finish(vs);
}
return;
}
vs->ws_input.offset += ret;
handshake_end = (uint8_t *)g_strstr_len((char *)vs->ws_input.buffer,
vs->ws_input.offset, WS_HANDSHAKE_END);
if (handshake_end) {
qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, NULL, vs);
vncws_process_handshake(vs, vs->ws_input.buffer, vs->ws_input.offset);
buffer_advance(&vs->ws_input, handshake_end - vs->ws_input.buffer +
strlen(WS_HANDSHAKE_END));
}
}
long vnc_client_read_ws(VncState *vs)
{
int ret, err;
uint8_t *payload;
size_t payload_size, frame_size;
VNC_DEBUG("Read websocket %p size %zd offset %zd\n", vs->ws_input.buffer,
vs->ws_input.capacity, vs->ws_input.offset);
buffer_reserve(&vs->ws_input, 4096);
ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), 4096);
if (!ret) {
return 0;
}
vs->ws_input.offset += ret;
/* make sure that nothing is left in the ws_input buffer */
do {
err = vncws_decode_frame(&vs->ws_input, &payload,
&payload_size, &frame_size);
if (err <= 0) {
return err;
}
buffer_reserve(&vs->input, payload_size);
buffer_append(&vs->input, payload, payload_size);
buffer_advance(&vs->ws_input, frame_size);
} while (vs->ws_input.offset > 0);
return ret;
}
long vnc_client_write_ws(VncState *vs)
{
long ret;
VNC_DEBUG("Write WS: Pending output %p size %zd offset %zd\n",
vs->output.buffer, vs->output.capacity, vs->output.offset);
vncws_encode_frame(&vs->ws_output, vs->output.buffer, vs->output.offset);
buffer_reset(&vs->output);
ret = vnc_client_write_buf(vs, vs->ws_output.buffer, vs->ws_output.offset);
if (!ret) {
return 0;
}
buffer_advance(&vs->ws_output, ret);
if (vs->ws_output.offset == 0) {
qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, NULL, vs);
}
return ret;
}
static char *vncws_extract_handshake_entry(const char *handshake,
size_t handshake_len, const char *name)
{
char *begin, *end, *ret = NULL;
char *line = g_strdup_printf("%s%s: ", WS_HANDSHAKE_DELIM, name);
begin = g_strstr_len(handshake, handshake_len, line);
if (begin != NULL) {
begin += strlen(line);
end = g_strstr_len(begin, handshake_len - (begin - handshake),
WS_HANDSHAKE_DELIM);
if (end != NULL) {
ret = g_strndup(begin, end - begin);
}
}
g_free(line);
return ret;
}
static void vncws_send_handshake_response(VncState *vs, const char* key)
{
char combined_key[WS_CLIENT_KEY_LEN + WS_GUID_LEN + 1];
unsigned char hash[SHA1_DIGEST_LEN];
size_t hash_size = sizeof(hash);
char *accept = NULL, *response = NULL;
gnutls_datum_t in;
int ret;
g_strlcpy(combined_key, key, WS_CLIENT_KEY_LEN + 1);
g_strlcat(combined_key, WS_GUID, WS_CLIENT_KEY_LEN + WS_GUID_LEN + 1);
/* hash and encode it */
in.data = (void *)combined_key;
in.size = WS_CLIENT_KEY_LEN + WS_GUID_LEN;
ret = gnutls_fingerprint(GNUTLS_DIG_SHA1, &in, hash, &hash_size);
if (ret == GNUTLS_E_SUCCESS && hash_size <= SHA1_DIGEST_LEN) {
accept = g_base64_encode(hash, hash_size);
}
if (accept == NULL) {
VNC_DEBUG("Hashing Websocket combined key failed\n");
vnc_client_error(vs);
return;
}
response = g_strdup_printf(WS_HANDSHAKE, accept);
vnc_write(vs, response, strlen(response));
vnc_flush(vs);
g_free(accept);
g_free(response);
vs->encode_ws = 1;
vnc_init_state(vs);
}
void vncws_process_handshake(VncState *vs, uint8_t *line, size_t size)
{
char *protocols = vncws_extract_handshake_entry((const char *)line, size,
"Sec-WebSocket-Protocol");
char *version = vncws_extract_handshake_entry((const char *)line, size,
"Sec-WebSocket-Version");
char *key = vncws_extract_handshake_entry((const char *)line, size,
"Sec-WebSocket-Key");
if (protocols && version && key
&& g_strrstr(protocols, "binary")
&& !strcmp(version, WS_SUPPORTED_VERSION)
&& strlen(key) == WS_CLIENT_KEY_LEN) {
vncws_send_handshake_response(vs, key);
} else {
VNC_DEBUG("Defective Websockets header or unsupported protocol\n");
vnc_client_error(vs);
}
g_free(protocols);
g_free(version);
g_free(key);
}
void vncws_encode_frame(Buffer *output, const void *payload,
const size_t payload_size)
{
size_t header_size = 0;
unsigned char opcode = WS_OPCODE_BINARY_FRAME;
union {
char buf[WS_HEAD_MAX_LEN];
WsHeader ws;
} header;
if (!payload_size) {
return;
}
header.ws.b0 = 0x80 | (opcode & 0x0f);
if (payload_size <= 125) {
header.ws.b1 = (uint8_t)payload_size;
header_size = 2;
} else if (payload_size < 65536) {
header.ws.b1 = 0x7e;
header.ws.u.s16.l16 = cpu_to_be16((uint16_t)payload_size);
header_size = 4;
} else {
header.ws.b1 = 0x7f;
header.ws.u.s64.l64 = cpu_to_be64(payload_size);
header_size = 10;
}
buffer_reserve(output, header_size + payload_size);
buffer_append(output, header.buf, header_size);
buffer_append(output, payload, payload_size);
}
int vncws_decode_frame(Buffer *input, uint8_t **payload,
size_t *payload_size, size_t *frame_size)
{
unsigned char opcode = 0, fin = 0, has_mask = 0;
size_t header_size = 0;
uint32_t *payload32;
WsHeader *header = (WsHeader *)input->buffer;
WsMask mask;
int i;
if (input->offset < WS_HEAD_MIN_LEN + 4) {
/* header not complete */
return 0;
}
fin = (header->b0 & 0x80) >> 7;
opcode = header->b0 & 0x0f;
has_mask = (header->b1 & 0x80) >> 7;
*payload_size = header->b1 & 0x7f;
if (opcode == WS_OPCODE_CLOSE) {
/* disconnect */
return -1;
}
/* Websocket frame sanity check:
* * Websocket fragmentation is not supported.
* * All websockets frames sent by a client have to be masked.
* * Only binary encoding is supported.
*/
if (!fin || !has_mask || opcode != WS_OPCODE_BINARY_FRAME) {
VNC_DEBUG("Received faulty/unsupported Websocket frame\n");
return -2;
}
if (*payload_size < 126) {
header_size = 6;
mask = header->u.m;
} else if (*payload_size == 126 && input->offset >= 8) {
*payload_size = be16_to_cpu(header->u.s16.l16);
header_size = 8;
mask = header->u.s16.m16;
} else if (*payload_size == 127 && input->offset >= 14) {
*payload_size = be64_to_cpu(header->u.s64.l64);
header_size = 14;
mask = header->u.s64.m64;
} else {
/* header not complete */
return 0;
}
*frame_size = header_size + *payload_size;
if (input->offset < *frame_size) {
/* frame not complete */
return 0;
}
*payload = input->buffer + header_size;
/* unmask frame */
/* process 1 frame (32 bit op) */
payload32 = (uint32_t *)(*payload);
for (i = 0; i < *payload_size / 4; i++) {
payload32[i] ^= mask.u;
}
/* process the remaining bytes (if any) */
for (i *= 4; i < *payload_size; i++) {
(*payload)[i] ^= mask.c[i % 4];
}
return 1;
}
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