for #250, calc and verify the crc32 of PAT.

@@ -222,6 +222,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #define ERROR_STREAM_CASTER_TS_HEADER       4012
 #define ERROR_STREAM_CASTER_TS_SYNC_BYTE    4013
 #define ERROR_STREAM_CASTER_TS_AF           4014
+#define ERROR_STREAM_CASTER_TS_CRC32        4015
 
 /**
 * whether the error code is an system control error.

@@ -617,7 +617,7 @@ int SrsTsAdaptationField::decode(SrsStream* stream)
         }
 
         char* pp = NULL;
-        char* p = stream->data();
+        char* p = stream->data() + stream->pos();
         stream->skip(6);
 
         pp = (char*)&program_clock_reference_base;
@@ -642,7 +642,7 @@ int SrsTsAdaptationField::decode(SrsStream* stream)
         }
 
         char* pp = NULL;
-        char* p = stream->data();
+        char* p = stream->data() + stream->pos();
         stream->skip(6);
 
         pp = (char*)&original_program_clock_reference_base;
@@ -831,6 +831,10 @@ int SrsTsPayloadPAT::decode(SrsStream* stream)
         return ret;
     }
 
+    // to calc the crc32
+    char* ppat = stream->data() + stream->pos();
+    int pat_pos = stream->pos();
+
     // atleast 8B without programs and crc32
     if (!stream->require(8)) {
         ret = ERROR_STREAM_CASTER_TS_AF;
@@ -894,7 +898,13 @@ int SrsTsPayloadPAT::decode(SrsStream* stream)
     }
     CRC_32 = stream->read_4bytes();
 
-    // TODO: FIXME: verfy crc32.
+    // verify crc32.
+    int32_t crc32 = srs_crc32(ppat, stream->pos() - pat_pos - 4);
+    if (crc32 != CRC_32) {
+        ret = ERROR_STREAM_CASTER_TS_CRC32;
+        srs_error("ts: verify PAT crc32 failed. ret=%d", ret);
+        return ret;
+    }
 
     return ret;
 }

@@ -326,3 +326,84 @@ bool srs_aac_startswith_adts(SrsStream* stream)
     return true;
 }
 
+/*
+ * MPEG2 transport stream (aka DVB) mux
+ * Copyright (c) 2003 Fabrice Bellard.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+static const u_int32_t crc_table[256] = {
+	0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
+	0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
+	0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70, 0x48d0c6c7,
+	0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
+	0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3,
+	0x709f7b7a, 0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
+	0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef,
+	0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
+	0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb,
+	0xceb42022, 0xca753d95, 0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
+	0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
+	0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
+	0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4,
+	0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
+	0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08,
+	0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
+	0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc,
+	0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
+	0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a, 0xe0b41de7, 0xe4750050,
+	0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
+	0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
+	0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
+	0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56, 0x4bc510e1,
+	0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
+	0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5,
+	0x3f9b762c, 0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
+	0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9,
+	0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
+	0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd,
+	0xcda1f604, 0xc960ebb3, 0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
+	0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
+	0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
+	0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2,
+	0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
+	0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e,
+	0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
+	0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a,
+	0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
+	0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c, 0xe3a1cbc1, 0xe760d676,
+	0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
+	0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
+	0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
+	0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
+};
+
+// @see http://www.stmc.edu.hk/~vincent/ffmpeg_0.4.9-pre1/libavformat/mpegtsenc.c
+unsigned int mpegts_crc32(const u_int8_t *data, int len)
+{
+    register int i;
+    unsigned int crc = 0xffffffff;
+    
+    for (i=0; i<len; i++)
+        crc = (crc << 8) ^ crc_table[((crc >> 24) ^ *data++) & 0xff];
+    
+    return crc;
+}
+
+u_int32_t srs_crc32(const void* buf, int size)
+{
+    return mpegts_crc32((const u_int8_t*)buf, size);
+}
+

@@ -80,5 +80,10 @@ extern bool srs_avc_startswith_annexb(SrsStream* stream, int* pnb_start_code = N
 */
 extern bool srs_aac_startswith_adts(SrsStream* stream);
 
+/**
+* cacl the crc32 of bytes in buf.
+*/
+extern u_int32_t srs_crc32(const void* buf, int size);
+
 #endif