/* * websockets.c - deal with WebSockets clients. * * This code should be independent of any changes in the RFB protocol. It is * an additional handshake and framing of normal sockets: * http://www.whatwg.org/specs/web-socket-protocol/ * */ /* * Copyright (C) 2010 Joel Martin * * 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, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, * USA. */ #ifdef __STRICT_ANSI__ #define _BSD_SOURCE #endif #include #include /* __b64_ntop */ /* errno */ #include #ifdef LIBVNCSERVER_HAVE_ENDIAN_H #include #elif LIBVNCSERVER_HAVE_SYS_ENDIAN_H #include #endif #ifdef LIBVNCSERVER_HAVE_SYS_TYPES_H #include #endif #include #include #include "rfb/rfbconfig.h" #include "rfbssl.h" #include "rfbcrypto.h" #define WS_NTOH64(n) htobe64(n) #define WS_NTOH32(n) htobe32(n) #define WS_NTOH16(n) htobe16(n) #define WS_HTON64(n) htobe64(n) #define WS_HTON16(n) htobe16(n) #define B64LEN(__x) (((__x + 2) / 3) * 12 / 3) #define WSHLENMAX 14 /* 2 + sizeof(uint64_t) + sizeof(uint32_t) */ enum { WEBSOCKETS_VERSION_HIXIE, WEBSOCKETS_VERSION_HYBI }; #if 0 #include static int gettid() { return (int)syscall(SYS_gettid); } #endif typedef int (*wsEncodeFunc)(rfbClientPtr cl, const char *src, int len, char **dst); typedef int (*wsDecodeFunc)(rfbClientPtr cl, char *dst, int len); typedef struct ws_ctx_s { char codeBuf[B64LEN(UPDATE_BUF_SIZE) + WSHLENMAX]; /* base64 + maximum frame header length */ char readbuf[8192]; int readbufstart; int readbuflen; int dblen; char carryBuf[3]; /* For base64 carry-over */ int carrylen; int version; int base64; wsEncodeFunc encode; wsDecodeFunc decode; } ws_ctx_t; typedef union ws_mask_s { char c[4]; uint32_t u; } ws_mask_t; typedef struct __attribute__ ((__packed__)) ws_header_s { unsigned char b0; unsigned char b1; union { struct __attribute__ ((__packed__)) { uint16_t l16; ws_mask_t m16; }; struct __attribute__ ((__packed__)) { uint64_t l64; ws_mask_t m64; }; ws_mask_t m; }; } ws_header_t; enum { WS_OPCODE_CONTINUATION = 0x0, WS_OPCODE_TEXT_FRAME, WS_OPCODE_BINARY_FRAME, WS_OPCODE_CLOSE = 0x8, WS_OPCODE_PING, WS_OPCODE_PONG }; #define FLASH_POLICY_RESPONSE "\n" #define SZ_FLASH_POLICY_RESPONSE 93 /* * draft-ietf-hybi-thewebsocketprotocol-10 * 5.2.2. Sending the Server's Opening Handshake */ #define GUID "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" #define SERVER_HANDSHAKE_HIXIE "HTTP/1.1 101 Web Socket Protocol Handshake\r\n\ Upgrade: WebSocket\r\n\ Connection: Upgrade\r\n\ %sWebSocket-Origin: %s\r\n\ %sWebSocket-Location: %s://%s%s\r\n\ %sWebSocket-Protocol: %s\r\n\ \r\n%s" #define SERVER_HANDSHAKE_HYBI "HTTP/1.1 101 Switching Protocols\r\n\ Upgrade: websocket\r\n\ Connection: Upgrade\r\n\ Sec-WebSocket-Accept: %s\r\n\ Sec-WebSocket-Protocol: %s\r\n\ \r\n" #define WEBSOCKETS_CLIENT_CONNECT_WAIT_MS 100 #define WEBSOCKETS_CLIENT_SEND_WAIT_MS 100 #define WEBSOCKETS_MAX_HANDSHAKE_LEN 4096 #if defined(__linux__) && defined(NEED_TIMEVAL) struct timeval { long int tv_sec,tv_usec; } ; #endif static rfbBool webSocketsHandshake(rfbClientPtr cl, char *scheme); void webSocketsGenMd5(char * target, char *key1, char *key2, char *key3); static int webSocketsEncodeHybi(rfbClientPtr cl, const char *src, int len, char **dst); static int webSocketsEncodeHixie(rfbClientPtr cl, const char *src, int len, char **dst); static int webSocketsDecodeHybi(rfbClientPtr cl, char *dst, int len); static int webSocketsDecodeHixie(rfbClientPtr cl, char *dst, int len); static int min (int a, int b) { return a < b ? a : b; } static void webSocketsGenSha1Key(char *target, int size, char *key) { struct iovec iov[2]; unsigned char hash[20]; iov[0].iov_base = key; iov[0].iov_len = strlen(key); iov[1].iov_base = GUID; iov[1].iov_len = sizeof(GUID) - 1; digestsha1(iov, 2, hash); if (-1 == __b64_ntop(hash, sizeof(hash), target, size)) rfbErr("b64_ntop failed\n"); } /* * rfbWebSocketsHandshake is called to handle new WebSockets connections */ rfbBool webSocketsCheck (rfbClientPtr cl) { char bbuf[4], *scheme; int ret; ret = rfbPeekExactTimeout(cl, bbuf, 4, WEBSOCKETS_CLIENT_CONNECT_WAIT_MS); if ((ret < 0) && (errno == ETIMEDOUT)) { rfbLog("Normal socket connection\n"); return TRUE; } else if (ret <= 0) { rfbErr("webSocketsHandshake: unknown connection error\n"); return FALSE; } if (strncmp(bbuf, "<", 1) == 0) { rfbLog("Got Flash policy request, sending response\n"); if (rfbWriteExact(cl, FLASH_POLICY_RESPONSE, SZ_FLASH_POLICY_RESPONSE) < 0) { rfbErr("webSocketsHandshake: failed sending Flash policy response"); } return FALSE; } else if (strncmp(bbuf, "\x16", 1) == 0 || strncmp(bbuf, "\x80", 1) == 0) { rfbLog("Got TLS/SSL WebSockets connection\n"); if (-1 == rfbssl_init(cl)) { rfbErr("webSocketsHandshake: rfbssl_init failed\n"); return FALSE; } ret = rfbPeekExactTimeout(cl, bbuf, 4, WEBSOCKETS_CLIENT_CONNECT_WAIT_MS); scheme = "wss"; } else { scheme = "ws"; } if (strncmp(bbuf, "GET ", 4) != 0) { rfbErr("webSocketsHandshake: invalid client header\n"); return FALSE; } rfbLog("Got '%s' WebSockets handshake\n", scheme); if (!webSocketsHandshake(cl, scheme)) { return FALSE; } /* Start WebSockets framing */ return TRUE; } static rfbBool webSocketsHandshake(rfbClientPtr cl, char *scheme) { char *buf, *response, *line; int n, linestart = 0, len = 0, llen, base64 = TRUE; char prefix[5], trailer[17]; char *path = NULL, *host = NULL, *origin = NULL, *protocol = NULL; char *key1 = NULL, *key2 = NULL, *key3 = NULL; char *sec_ws_origin = NULL; char *sec_ws_key = NULL; char sec_ws_version = 0; ws_ctx_t *wsctx = NULL; buf = (char *) malloc(WEBSOCKETS_MAX_HANDSHAKE_LEN); if (!buf) { rfbLogPerror("webSocketsHandshake: malloc"); return FALSE; } response = (char *) malloc(WEBSOCKETS_MAX_HANDSHAKE_LEN); if (!response) { free(buf); rfbLogPerror("webSocketsHandshake: malloc"); return FALSE; } while (len < WEBSOCKETS_MAX_HANDSHAKE_LEN-1) { if ((n = rfbReadExactTimeout(cl, buf+len, 1, WEBSOCKETS_CLIENT_SEND_WAIT_MS)) <= 0) { if ((n < 0) && (errno == ETIMEDOUT)) { break; } if (n == 0) rfbLog("webSocketsHandshake: client gone\n"); else rfbLogPerror("webSocketsHandshake: read"); free(response); free(buf); return FALSE; } len += 1; llen = len - linestart; if (((llen >= 2)) && (buf[len-1] == '\n')) { line = buf+linestart; if ((llen == 2) && (strncmp("\r\n", line, 2) == 0)) { if (key1 && key2) { if ((n = rfbReadExact(cl, buf+len, 8)) <= 0) { if ((n < 0) && (errno == ETIMEDOUT)) { break; } if (n == 0) rfbLog("webSocketsHandshake: client gone\n"); else rfbLogPerror("webSocketsHandshake: read"); free(response); free(buf); return FALSE; } rfbLog("Got key3\n"); key3 = buf+len; len += 8; } else { buf[len] = '\0'; } break; } else if ((llen >= 16) && ((strncmp("GET ", line, min(llen,4))) == 0)) { /* 16 = 4 ("GET ") + 1 ("/.*") + 11 (" HTTP/1.1\r\n") */ path = line+4; buf[len-11] = '\0'; /* Trim trailing " HTTP/1.1\r\n" */ cl->wspath = strdup(path); /* rfbLog("Got path: %s\n", path); */ } else if ((strncasecmp("host: ", line, min(llen,6))) == 0) { host = line+6; buf[len-2] = '\0'; /* rfbLog("Got host: %s\n", host); */ } else if ((strncasecmp("origin: ", line, min(llen,8))) == 0) { origin = line+8; buf[len-2] = '\0'; /* rfbLog("Got origin: %s\n", origin); */ } else if ((strncasecmp("sec-websocket-key1: ", line, min(llen,20))) == 0) { key1 = line+20; buf[len-2] = '\0'; /* rfbLog("Got key1: %s\n", key1); */ } else if ((strncasecmp("sec-websocket-key2: ", line, min(llen,20))) == 0) { key2 = line+20; buf[len-2] = '\0'; /* rfbLog("Got key2: %s\n", key2); */ /* HyBI */ } else if ((strncasecmp("sec-websocket-protocol: ", line, min(llen,24))) == 0) { protocol = line+24; buf[len-2] = '\0'; rfbLog("Got protocol: %s\n", protocol); } else if ((strncasecmp("sec-websocket-origin: ", line, min(llen,22))) == 0) { sec_ws_origin = line+22; buf[len-2] = '\0'; } else if ((strncasecmp("sec-websocket-key: ", line, min(llen,19))) == 0) { sec_ws_key = line+19; buf[len-2] = '\0'; } else if ((strncasecmp("sec-websocket-version: ", line, min(llen,23))) == 0) { sec_ws_version = strtol(line+23, NULL, 10); buf[len-2] = '\0'; } linestart = len; } } if (!(path && host && (origin || sec_ws_origin))) { rfbErr("webSocketsHandshake: incomplete client handshake\n"); free(response); free(buf); return FALSE; } if ((protocol) && (strstr(protocol, "binary"))) { if (! sec_ws_version) { rfbErr("webSocketsHandshake: 'binary' protocol not supported with Hixie\n"); free(response); free(buf); return FALSE; } rfbLog(" - webSocketsHandshake: using binary/raw encoding\n"); base64 = FALSE; protocol = "binary"; } else { rfbLog(" - webSocketsHandshake: using base64 encoding\n"); base64 = TRUE; if ((protocol) && (strstr(protocol, "base64"))) { protocol = "base64"; } else { protocol = ""; } } /* * Generate the WebSockets server response based on the the headers sent * by the client. */ if (sec_ws_version) { char accept[B64LEN(SHA1_HASH_SIZE) + 1]; rfbLog(" - WebSockets client version hybi-%02d\n", sec_ws_version); webSocketsGenSha1Key(accept, sizeof(accept), sec_ws_key); len = snprintf(response, WEBSOCKETS_MAX_HANDSHAKE_LEN, SERVER_HANDSHAKE_HYBI, accept, protocol); } else { /* older hixie handshake, this could be removed if * a final standard is established */ if (!(key1 && key2 && key3)) { rfbLog(" - WebSockets client version hixie-75\n"); prefix[0] = '\0'; trailer[0] = '\0'; } else { rfbLog(" - WebSockets client version hixie-76\n"); snprintf(prefix, 5, "Sec-"); webSocketsGenMd5(trailer, key1, key2, key3); } len = snprintf(response, WEBSOCKETS_MAX_HANDSHAKE_LEN, SERVER_HANDSHAKE_HIXIE, prefix, origin, prefix, scheme, host, path, prefix, protocol, trailer); } if (rfbWriteExact(cl, response, len) < 0) { rfbErr("webSocketsHandshake: failed sending WebSockets response\n"); free(response); free(buf); return FALSE; } /* rfbLog("webSocketsHandshake: %s\n", response); */ free(response); free(buf); wsctx = calloc(1, sizeof(ws_ctx_t)); if (sec_ws_version) { wsctx->version = WEBSOCKETS_VERSION_HYBI; wsctx->encode = webSocketsEncodeHybi; wsctx->decode = webSocketsDecodeHybi; } else { wsctx->version = WEBSOCKETS_VERSION_HIXIE; wsctx->encode = webSocketsEncodeHixie; wsctx->decode = webSocketsDecodeHixie; } wsctx->base64 = base64; cl->wsctx = (wsCtx *)wsctx; return TRUE; } void webSocketsGenMd5(char * target, char *key1, char *key2, char *key3) { unsigned int i, spaces1 = 0, spaces2 = 0; unsigned long num1 = 0, num2 = 0; unsigned char buf[17]; struct iovec iov[1]; for (i=0; i < strlen(key1); i++) { if (key1[i] == ' ') { spaces1 += 1; } if ((key1[i] >= 48) && (key1[i] <= 57)) { num1 = num1 * 10 + (key1[i] - 48); } } num1 = num1 / spaces1; for (i=0; i < strlen(key2); i++) { if (key2[i] == ' ') { spaces2 += 1; } if ((key2[i] >= 48) && (key2[i] <= 57)) { num2 = num2 * 10 + (key2[i] - 48); } } num2 = num2 / spaces2; /* Pack it big-endian */ buf[0] = (num1 & 0xff000000) >> 24; buf[1] = (num1 & 0xff0000) >> 16; buf[2] = (num1 & 0xff00) >> 8; buf[3] = num1 & 0xff; buf[4] = (num2 & 0xff000000) >> 24; buf[5] = (num2 & 0xff0000) >> 16; buf[6] = (num2 & 0xff00) >> 8; buf[7] = num2 & 0xff; strncpy((char *)buf+8, key3, 8); buf[16] = '\0'; iov[0].iov_base = buf; iov[0].iov_len = 16; digestmd5(iov, 1, target); target[16] = '\0'; return; } static int webSocketsEncodeHixie(rfbClientPtr cl, const char *src, int len, char **dst) { int sz = 0; ws_ctx_t *wsctx = (ws_ctx_t *)cl->wsctx; wsctx->codeBuf[sz++] = '\x00'; len = __b64_ntop((unsigned char *)src, len, wsctx->codeBuf+sz, sizeof(wsctx->codeBuf) - (sz + 1)); if (len < 0) { return len; } sz += len; wsctx->codeBuf[sz++] = '\xff'; *dst = wsctx->codeBuf; return sz; } static int ws_read(rfbClientPtr cl, char *buf, int len) { int n; if (cl->sslctx) { n = rfbssl_read(cl, buf, len); } else { n = read(cl->sock, buf, len); } return n; } static int ws_peek(rfbClientPtr cl, char *buf, int len) { int n; if (cl->sslctx) { n = rfbssl_peek(cl, buf, len); } else { while (-1 == (n = recv(cl->sock, buf, len, MSG_PEEK))) { if (errno != EAGAIN) break; } } return n; } static int webSocketsDecodeHixie(rfbClientPtr cl, char *dst, int len) { int retlen = 0, n, i, avail, modlen, needlen; char *buf, *end = NULL; ws_ctx_t *wsctx = (ws_ctx_t *)cl->wsctx; buf = wsctx->codeBuf; n = ws_peek(cl, buf, len*2+2); if (n <= 0) { /* save errno because rfbErr() will tamper it */ int olderrno = errno; rfbErr("%s: peek (%d) %m\n", __func__, errno); errno = olderrno; return n; } /* Base64 encoded WebSockets stream */ if (buf[0] == '\xff') { i = ws_read(cl, buf, 1); /* Consume marker */ buf++; n--; } if (n == 0) { errno = EAGAIN; return -1; } if (buf[0] == '\x00') { i = ws_read(cl, buf, 1); /* Consume marker */ buf++; n--; } if (n == 0) { errno = EAGAIN; return -1; } /* end = memchr(buf, '\xff', len*2+2); */ end = memchr(buf, '\xff', n); if (!end) { end = buf + n; } avail = end - buf; len -= wsctx->carrylen; /* Determine how much base64 data we need */ modlen = len + (len+2)/3; needlen = modlen; if (needlen % 4) { needlen += 4 - (needlen % 4); } if (needlen > avail) { /* rfbLog("Waiting for more base64 data\n"); */ errno = EAGAIN; return -1; } /* Any carryover from previous decode */ for (i=0; i < wsctx->carrylen; i++) { /* rfbLog("Adding carryover %d\n", wsctx->carryBuf[i]); */ dst[i] = wsctx->carryBuf[i]; retlen += 1; } /* Decode the rest of what we need */ buf[needlen] = '\x00'; /* Replace end marker with end of string */ /* rfbLog("buf: %s\n", buf); */ n = __b64_pton(buf, (unsigned char *)dst+retlen, 2+len); if (n < len) { rfbErr("Base64 decode error\n"); errno = EIO; return -1; } retlen += n; /* Consume the data from socket */ i = ws_read(cl, buf, needlen); wsctx->carrylen = n - len; retlen -= wsctx->carrylen; for (i=0; i < wsctx->carrylen; i++) { /* rfbLog("Saving carryover %d\n", dst[retlen + i]); */ wsctx->carryBuf[i] = dst[retlen + i]; } /* rfbLog("<< webSocketsDecode, retlen: %d\n", retlen); */ return retlen; } static int webSocketsDecodeHybi(rfbClientPtr cl, char *dst, int len) { char *buf, *payload; uint32_t *payload32; int ret = -1, result = -1; int total = 0; ws_mask_t mask; ws_header_t *header; int i; unsigned char opcode; ws_ctx_t *wsctx = (ws_ctx_t *)cl->wsctx; int flength, fhlen; /* int fin; */ /* not used atm */ /* rfbLog(" <== %s[%d]: %d cl: %p, wsctx: %p-%p (%d)\n", __func__, gettid(), len, cl, wsctx, (char *)wsctx + sizeof(ws_ctx_t), sizeof(ws_ctx_t)); */ if (wsctx->readbuflen) { /* simply return what we have */ if (wsctx->readbuflen > len) { memcpy(dst, wsctx->readbuf + wsctx->readbufstart, len); result = len; wsctx->readbuflen -= len; wsctx->readbufstart += len; } else { memcpy(dst, wsctx->readbuf + wsctx->readbufstart, wsctx->readbuflen); result = wsctx->readbuflen; wsctx->readbuflen = 0; wsctx->readbufstart = 0; } goto spor; } buf = wsctx->codeBuf; header = (ws_header_t *)wsctx->codeBuf; ret = ws_peek(cl, buf, B64LEN(len) + WSHLENMAX); if (ret < 2) { /* save errno because rfbErr() will tamper it */ if (-1 == ret) { int olderrno = errno; rfbErr("%s: peek; %m\n", __func__); errno = olderrno; } else if (0 == ret) { result = 0; } else { errno = EAGAIN; } goto spor; } opcode = header->b0 & 0x0f; /* fin = (header->b0 & 0x80) >> 7; */ /* not used atm */ flength = header->b1 & 0x7f; /* * 4.3. Client-to-Server Masking * * The client MUST mask all frames sent to the server. A server MUST * close the connection upon receiving a frame with the MASK bit set to 0. **/ if (!(header->b1 & 0x80)) { rfbErr("%s: got frame without mask\n", __func__, ret); errno = EIO; goto spor; } if (flength < 126) { fhlen = 2; mask = header->m; } else if (flength == 126 && 4 <= ret) { flength = WS_NTOH16(header->l16); fhlen = 4; mask = header->m16; } else if (flength == 127 && 10 <= ret) { flength = WS_NTOH64(header->l64); fhlen = 10; mask = header->m64; } else { /* Incomplete frame header */ rfbErr("%s: incomplete frame header\n", __func__, ret); errno = EIO; goto spor; } /* absolute length of frame */ total = fhlen + flength + 4; payload = buf + fhlen + 4; /* header length + mask */ if (-1 == (ret = ws_read(cl, buf, total))) { int olderrno = errno; rfbErr("%s: read; %m", __func__); errno = olderrno; return ret; } else if (ret < total) { /* GT TODO: hmm? */ rfbLog("%s: read; got partial data\n", __func__); } else { buf[ret] = '\0'; } /* process 1 frame (32 bit op) */ payload32 = (uint32_t *)payload; for (i = 0; i < flength / 4; i++) { payload32[i] ^= mask.u; } /* process the remaining bytes (if any) */ for (i*=4; i < flength; i++) { payload[i] ^= mask.c[i % 4]; } switch (opcode) { case WS_OPCODE_CLOSE: rfbLog("got closure, reason %d\n", WS_NTOH16(((uint16_t *)payload)[0])); errno = ECONNRESET; break; case WS_OPCODE_TEXT_FRAME: if (-1 == (flength = __b64_pton(payload, (unsigned char *)wsctx->codeBuf, sizeof(wsctx->codeBuf)))) { rfbErr("%s: Base64 decode error; %m\n", __func__); break; } payload = wsctx->codeBuf; /* fall through */ case WS_OPCODE_BINARY_FRAME: if (flength > len) { memcpy(wsctx->readbuf, payload + len, flength - len); wsctx->readbufstart = 0; wsctx->readbuflen = flength - len; flength = len; } memcpy(dst, payload, flength); result = flength; break; default: rfbErr("%s: unhandled opcode %d, b0: %02x, b1: %02x\n", __func__, (int)opcode, header->b0, header->b1); } /* single point of return, if someone has questions :-) */ spor: /* rfbLog("%s: ret: %d/%d\n", __func__, result, len); */ return result; } static int webSocketsEncodeHybi(rfbClientPtr cl, const char *src, int len, char **dst) { int blen, ret = -1, sz = 0; unsigned char opcode = '\0'; /* TODO: option! */ ws_header_t *header; ws_ctx_t *wsctx = (ws_ctx_t *)cl->wsctx; /* Optional opcode: * 0x0 - continuation * 0x1 - text frame (base64 encode buf) * 0x2 - binary frame (use raw buf) * 0x8 - connection close * 0x9 - ping * 0xA - pong **/ if (!len) { /* nothing to encode */ return 0; } header = (ws_header_t *)wsctx->codeBuf; if (wsctx->base64) { opcode = WS_OPCODE_TEXT_FRAME; /* calculate the resulting size */ blen = B64LEN(len); } else { blen = len; } header->b0 = 0x80 | (opcode & 0x0f); if (blen <= 125) { header->b1 = (uint8_t)blen; sz = 2; } else if (blen <= 65536) { header->b1 = 0x7e; header->l16 = WS_HTON16((uint16_t)blen); sz = 4; } else { header->b1 = 0x7f; header->l64 = WS_HTON64(blen); sz = 10; } if (wsctx->base64) { if (-1 == (ret = __b64_ntop((unsigned char *)src, len, wsctx->codeBuf + sz, sizeof(wsctx->codeBuf) - sz))) { rfbErr("%s: Base 64 encode failed\n", __func__); } else { if (ret != blen) rfbErr("%s: Base 64 encode; something weird happened\n", __func__); ret += sz; } } else { memcpy(wsctx->codeBuf + sz, src, len); ret = sz + len; } *dst = wsctx->codeBuf; return ret; } int webSocketsEncode(rfbClientPtr cl, const char *src, int len, char **dst) { return ((ws_ctx_t *)cl->wsctx)->encode(cl, src, len, dst); } int webSocketsDecode(rfbClientPtr cl, char *dst, int len) { return ((ws_ctx_t *)cl->wsctx)->decode(cl, dst, len); } /* returns TRUE if client sent a close frame or a single 'end of frame' * marker was received, FALSE otherwise * * Note: This is a Hixie-only hack! **/ rfbBool webSocketCheckDisconnect(rfbClientPtr cl) { ws_ctx_t *wsctx = (ws_ctx_t *)cl->wsctx; /* With Base64 encoding we need at least 4 bytes */ char peekbuf[4]; int n; if (wsctx->version == WEBSOCKETS_VERSION_HYBI) return FALSE; if (cl->sslctx) n = rfbssl_peek(cl, peekbuf, 4); else n = recv(cl->sock, peekbuf, 4, MSG_PEEK); if (n <= 0) { if (n != 0) rfbErr("%s: peek; %m", __func__); rfbCloseClient(cl); return TRUE; } if (peekbuf[0] == '\xff') { int doclose = 0; /* Make sure we don't miss a client disconnect on an end frame * marker. Because we use a peek buffer in some cases it is not * applicable to wait for more data per select(). */ switch (n) { case 3: if (peekbuf[1] == '\xff' && peekbuf[2] == '\x00') doclose = 1; break; case 2: if (peekbuf[1] == '\x00') doclose = 1; break; default: return FALSE; } if (cl->sslctx) n = rfbssl_read(cl, peekbuf, n); else n = read(cl->sock, peekbuf, n); if (doclose) { rfbErr("%s: websocket close frame received\n", __func__); rfbCloseClient(cl); } return TRUE; } return FALSE; }