Add websocket example that supports permessage-deflate extension

examples/websocket_mbedtls/tinfgzip.c

@@ -0,0 +1,124 @@
+/*
+ * tinfgzip  -  tiny gzip decompressor
+ *
+ * Copyright (c) 2003 by Joergen Ibsen / Jibz
+ * All Rights Reserved
+ *
+ * http://www.ibsensoftware.com/
+ *
+ * This software is provided 'as-is', without any express
+ * or implied warranty.  In no event will the authors be
+ * held liable for any damages arising from the use of
+ * this software.
+ *
+ * Permission is granted to anyone to use this software
+ * for any purpose, including commercial applications,
+ * and to alter it and redistribute it freely, subject to
+ * the following restrictions:
+ *
+ * 1. The origin of this software must not be
+ *    misrepresented; you must not claim that you
+ *    wrote the original software. If you use this
+ *    software in a product, an acknowledgment in
+ *    the product documentation would be appreciated
+ *    but is not required.
+ *
+ * 2. Altered source versions must be plainly marked
+ *    as such, and must not be misrepresented as
+ *    being the original software.
+ *
+ * 3. This notice may not be removed or altered from
+ *    any source distribution.
+ */
+
+#include "tinf.h"
+
+#define FTEXT    1
+#define FHCRC    2
+#define FEXTRA   4
+#define FNAME    8
+#define FCOMMENT 16
+
+int tinf_gzip_uncompress(void *dest, unsigned int *destLen,
+                         const void *source, unsigned int sourceLen)
+{
+    unsigned char *src = (unsigned char *)source;
+    unsigned char *dst = (unsigned char *)dest;
+    unsigned char *start;
+    unsigned int dlen, crc32;
+    int res;
+    unsigned char flg;
+
+    /* -- check format -- */
+
+    /* check id bytes */
+    if (src[0] != 0x1f || src[1] != 0x8b) return TINF_DATA_ERROR;
+
+    /* check method is deflate */
+    if (src[2] != 8) return TINF_DATA_ERROR;
+
+    /* get flag byte */
+    flg = src[3];
+
+    /* check that reserved bits are zero */
+    if (flg & 0xe0) return TINF_DATA_ERROR;
+
+    /* -- find start of compressed data -- */
+
+    /* skip base header of 10 bytes */
+    start = src + 10;
+
+    /* skip extra data if present */
+    if (flg & FEXTRA)
+    {
+       unsigned int xlen = start[1];
+       xlen = 256*xlen + start[0];
+       start += xlen + 2;
+    }
+
+    /* skip file name if present */
+    if (flg & FNAME) { while (*start) ++start; ++start; }
+
+    /* skip file comment if present */
+    if (flg & FCOMMENT) { while (*start) ++start; ++start; }
+
+    /* check header crc if present */
+    if (flg & FHCRC)
+    {
+       unsigned int hcrc = start[1];
+       hcrc = 256*hcrc + start[0];
+
+       if (hcrc != (tinf_crc32(src, start - src) & 0x0000ffff))
+          return TINF_DATA_ERROR;
+
+       start += 2;
+    }
+
+    /* -- get decompressed length -- */
+
+    dlen =            src[sourceLen - 1];
+    dlen = 256*dlen + src[sourceLen - 2];
+    dlen = 256*dlen + src[sourceLen - 3];
+    dlen = 256*dlen + src[sourceLen - 4];
+
+    /* -- get crc32 of decompressed data -- */
+
+    crc32 =             src[sourceLen - 5];
+    crc32 = 256*crc32 + src[sourceLen - 6];
+    crc32 = 256*crc32 + src[sourceLen - 7];
+    crc32 = 256*crc32 + src[sourceLen - 8];
+
+    /* -- decompress data -- */
+
+    res = tinf_uncompress(dst, destLen, start, src + sourceLen - start - 8);
+
+    if (res != TINF_OK) return TINF_DATA_ERROR;
+
+    if (*destLen != dlen) return TINF_DATA_ERROR;
+
+    /* -- check CRC32 checksum -- */
+
+    if (crc32 != tinf_crc32(dst, dlen)) return TINF_DATA_ERROR;
+
+    return TINF_OK;
+}