added crc verification to transport layer

makefile

@@ -21,7 +21,8 @@ SOURCES :=  src/shellmatta.c                \
             src/shellmatta_utils.c          \
             src/shellmatta_escape.c         \
             src/shellmatta_opt.c            \
-            src/shellmatta_transport.c
+            src/shellmatta_transport.c      \
+            src/shellmatta_crc.c
 
 INCLUDES    := api .
 

src/shellmatta.c

@@ -441,29 +441,32 @@ shellmatta_retCode_t shellmatta_processData(shellmatta_handle_t     handle,
 
                 case STATE_GET_CRC:
                     transportLayerInst.continueStep = false;
-                    crc32 |= data[headerCounter] << (SHELLMATTA_LENGTH_CRC - crcCounter++) * 8u;
+                    crc32 |= (uint8_t)data[headerCounter] << (SHELLMATTA_LENGTH_CRC - 1 - crcCounter++) * 8u;
                     break;
                 
                 default:
                     break;
                 }
                 /* handling of transport layer fsm */
-                ret = shellmatta_handle_transport_fsm(&transportLayerInst, data);
+                ret = shellmatta_handle_transport_fsm(data);
                 
                 if (SHELLMATTA_ERROR == ret)
                 {
                     // TODO: Better error handling
                     /* error in this case means crc error */
+                    utils_terminateInput(inst);
+                    shellmatta_reset_transport();
                     shellmatta_printf(handle, "crc error\r\n");
-                    transportLayerInst.state = STATE_GET_SOH;
+                    return SHELLMATTA_OK;
                 }
 
                 headerCounter++;
 
                 if (transportLayerInst.state == STATE_PROCESS_PAYLOAD)
                 {
+                    /* recursive call with complete payload */
                     shellmatta_processData(handle, payloadBuffer, payloadLength);
-                    shellmatta_handle_transport_fsm(&transportLayerInst, data);
+                    shellmatta_handle_transport_fsm(data);
                     return SHELLMATTA_OK;
                 }
             }

src/shellmatta_crc.c

@@ -0,0 +1,133 @@
+/**
+ * @file    shellmatta_crc.c
+ * @brief   cyclic redundancy check functions of shellmatta
+ * @author  Simon Fischer <fischer.simon.1991@gmail.com>
+ */
+
+#include "shellmatta_crc.h"
+
+#ifndef CRC_NO_LOOKUP
+uint32_t crc32Table[] = {
+    /* 0x04c11db7 reflected */
+    0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
+    0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
+    0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
+    0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
+    0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
+    0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
+    0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
+    0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
+    0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
+    0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
+    0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
+    0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
+    0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
+    0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
+    0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
+    0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
+    0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
+    0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
+    0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
+    0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
+    0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
+    0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
+    0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
+    0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
+    0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
+    0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
+    0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
+    0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
+    0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
+    0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
+    0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
+    0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
+};
+#endif
+
+/**
+ * @brief       Reverses bits of a value.
+ * @param[in]   x       input value
+ * @param[in]   size    amount of bits used in value
+ */
+uint32_t reverse(uint32_t x, int bits)
+{
+    x = ((x & 0x55555555) << 1) | ((x & 0xAAAAAAAA) >> 1); // Swap _<>_
+    x = ((x & 0x33333333) << 2) | ((x & 0xCCCCCCCC) >> 2); // Swap __<>__
+    x = ((x & 0x0F0F0F0F) << 4) | ((x & 0xF0F0F0F0) >> 4); // Swap ____<>____
+    x = ((x & 0x00FF00FF) << 8) | ((x & 0xFF00FF00) >> 8); // Swap ...
+    x = ((x & 0x0000FFFF) << 16) | ((x & 0xFFFF0000) >> 16); // Swap ...
+    return x >> (32 - bits);
+}
+
+/**
+ * @brief       Computes the crc32-checksum of a buffer.
+ * @param[in]   data            pointer to data buffer
+ * @param[in]   size            amount of bytes to be processed
+ */
+uint32_t crc32Calc(char* data, uint16_t size)
+{
+    #ifdef  CRC_NO_LOOKUP
+        return crc32Slow(data, size);
+    #else
+        return crc32Fast(data, size, crc32Table);
+    #endif
+}
+
+/**
+ * @brief       Computes the crc32-checksum of a buffer. O(4n)
+ * @param[in]   data            pointer to data buffer
+ * @param[in]   size            amount of bytes to be processed
+ */
+uint32_t crc32Slow(char* data, uint16_t size)
+{
+    uint16_t i;
+    uint8_t j;
+    uint8_t pivotByte;
+    uint32_t polynom = reverse(CRC32_POLYNOM, 32);
+
+    /* start with 0xffffffff */
+    uint32_t crcTemp = 0xffffffff;
+
+    for (i = 0; i < size; i++)
+    {
+        pivotByte = data[i];
+        for (j = 0; j < BITS_PER_BYTE; j++)
+        {
+            if ((crcTemp & 1) != (pivotByte & 1))
+            {
+                crcTemp = (crcTemp >> 1) ^ polynom;
+            }
+            else
+            {
+                crcTemp >>= 1;
+            }
+            pivotByte >>= 1;
+        }
+    }
+
+    /* final xor */
+    crcTemp ^= 0xffffffff;
+
+    return crcTemp;
+}
+
+#ifndef CRC_NO_LOOKUP
+/**
+ * @brief       Computes the crc32-checksum of a buffer. O(n)
+ * @param[in]   data            pointer to data buffer
+ * @param[in]   size            amount of bytes to be processed
+ * @param[in]   lookupTable     pointer to uint32_t lookup table for crc computation
+ */
+uint32_t crc32Fast(char* data, uint16_t size, uint32_t* lookupTable)
+{
+    uint16_t i;
+    uint32_t crcTemp = 0xffffffff;
+
+    for (i = 0; i < size; i++)
+    {
+        crcTemp = lookupTable[data[i] ^ (crcTemp & 0xff)] ^ (crcTemp >> 8);
+    }
+
+    return ~crcTemp;
+}
+#endif

src/shellmatta_crc.h

@@ -0,0 +1,22 @@
+/**
+ * @file    shellmatta_crc.h
+ * @brief   cyclic redundancy check functions of shellmatta
+ * @author  Simon Fischer <fischer.simon.1991@gmail.com>
+ */
+
+#ifndef _SHELLMATTA_CRC_H_
+#define _SHELLMATTA_CRC_H_
+
+#include <stdint.h>
+
+#define CRC32_POLYNOM   0x04c11db7      /* crc-32 ethernet 802.3 */
+#define BITS_PER_BYTE   ((uint8_t)8)    /* amount of bits per byte; to avoid magic number */
+
+uint32_t crc32Calc(char* data, uint16_t size);
+uint32_t crc32Slow(char* data, uint16_t size);
+
+#ifndef CRC_NO_LOOKUP
+uint32_t crc32Fast(char* data, uint16_t size, uint32_t* lookupTable);
+#endif
+
+#endif /* _SHELLMATTA_CRC_H_ */

src/shellmatta_transport.c

@@ -1,10 +1,11 @@
 /**
- * @file    shellmatta_transport.h
+ * @file    shellmatta_transport.c
  * @brief   transport layer functions of shellmatta
  * @author  Simon Fischer <fischer.simon.1991@gmail.com>
  */
 
 #include "shellmatta_transport.h"
+#include "shellmatta_crc.h"
 #include <string.h>
 
 /* init global variables */
@@ -39,20 +40,37 @@ shellmatta_retCode_t shellmatta_init_transport_inst()
     return SHELLMATTA_OK;
 }
 
-shellmatta_retCode_t shellmatta_handle_transport_fsm(shellmatta_transport_layer_t *transportLayer, char *data)
+shellmatta_retCode_t shellmatta_reset_transport()
 {
-    switch (transportLayer->state)
+    transportLayerInst.state = STATE_GET_SOH;
+    protocolVersion = 0u;
+    packetType      = 0u;
+    payloadLength   = 0u;
+    source          = 0u;
+    destination     = 0u;
+    crc32           = 0u;
+    payloadCounter  = 0u;
+    crcCounter      = 0u;
+    transportLayerInst.active = false;
+    memset(payloadBuffer, 0, SHELLMATTA_PAYLOAD_MAXLENGTH + 1);
+
+    return SHELLMATTA_OK;
+}
+
+shellmatta_retCode_t shellmatta_handle_transport_fsm(char *data)
+{
+    switch (transportLayerInst.state)
     {
     case STATE_GET_SOH:
         if (SHELLMATTA_START_OF_HEADER == *data)
         {
-            transportLayer->state = STATE_GET_PROTOCOL_VERSION;
-            transportLayer->active = true;
+            transportLayerInst.state = STATE_GET_PROTOCOL_VERSION;
+            transportLayerInst.active = true;
         }
         else
         {
-            transportLayer->state = STATE_MANUAL_INPUT;
-            transportLayer->active = false;
+            transportLayerInst.state = STATE_MANUAL_INPUT;
+            transportLayerInst.active = false;
         }
         break;
 
@@ -60,48 +78,63 @@ shellmatta_retCode_t shellmatta_handle_transport_fsm(shellmatta_transport_layer_
         break;
 
     case STATE_GET_PROTOCOL_VERSION:
-        transportLayer->state = STATE_GET_PACKET_TYPE;
+        transportLayerInst.state = STATE_GET_PACKET_TYPE;
         break;
 
     case STATE_GET_PACKET_TYPE:
-        transportLayer->state = STATE_GET_PAYLOAD_LENGTH;
+        transportLayerInst.state = STATE_GET_PAYLOAD_LENGTH;
         break;
 
     case STATE_GET_PAYLOAD_LENGTH:
-        transportLayer->state = STATE_GET_SOURCE;
+        transportLayerInst.state = STATE_GET_SOURCE;
         break;
 
     case STATE_GET_SOURCE:
-        transportLayer->state = STATE_GET_DESTINATION;
+        transportLayerInst.state = STATE_GET_DESTINATION;
         break;
 
     case STATE_GET_DESTINATION:
-        transportLayer->state = STATE_GET_H2S_SEQUENCE_CNT;
+        transportLayerInst.state = STATE_GET_H2S_SEQUENCE_CNT;
         break;
 
     case STATE_GET_H2S_SEQUENCE_CNT:
-        transportLayer->state = STATE_GET_S2H_SEQUENCE_CNT;
+        transportLayerInst.state = STATE_GET_S2H_SEQUENCE_CNT;
         break;
 
     case STATE_GET_S2H_SEQUENCE_CNT:
-        transportLayer->state = STATE_GET_PAYLOAD;
+        transportLayerInst.state = STATE_GET_PAYLOAD;
         break;
 
     case STATE_GET_PAYLOAD:
         if (    (payloadLength <= payloadCounter)
-            &&  (true == transportLayer->active))
+            &&  (true == transportLayerInst.active))
         {
-            transportLayer->state = STATE_GET_CRC;
+            transportLayerInst.state = STATE_GET_CRC;
         }
         break;
 
     case STATE_GET_CRC:
         if (SHELLMATTA_LENGTH_CRC <= crcCounter)
         {
-            /* debug check for crc 0x01 0x01 0x01 0x01 */
-            if (crc32 == 16843009u)
+            char data[SHELLMATTA_PAYLOAD_MAXLENGTH + 1 + SHELLMATTA_HEADER_LENGTH];
+            memset(data, 0, SHELLMATTA_PAYLOAD_MAXLENGTH + 1 + SHELLMATTA_HEADER_LENGTH);
+            data[0] = SHELLMATTA_START_OF_HEADER;
+            data[1] = protocolVersion;
+            data[2] = packetType;
+            data[3] = payloadLength;
+            data[4] = source;
+            data[5] = destination;
+            data[6] = transportLayerInst.h2s_sequenceCnt;
+            data[7] = transportLayerInst.s2h_sequenceCnt;
+            strncat(&data[8], payloadBuffer, payloadLength);
+
+            uint32_t refCrc;
+
+            refCrc = crc32Calc(data, SHELLMATTA_HEADER_LENGTH + payloadLength);
+
+            if (crc32 == refCrc)
             {
-                transportLayer->state = STATE_PROCESS_PAYLOAD;
+                transportLayerInst.state = STATE_PROCESS_PAYLOAD;
                 break;
             }
             else
@@ -112,7 +145,7 @@ shellmatta_retCode_t shellmatta_handle_transport_fsm(shellmatta_transport_layer_
         break;
 
     case STATE_PROCESS_PAYLOAD:
-        transportLayer->state = STATE_GET_SOH;
+        transportLayerInst.state = STATE_GET_SOH;
         protocolVersion = 0u;
         packetType      = 0u;
         payloadLength   = 0u;
@@ -121,7 +154,7 @@ shellmatta_retCode_t shellmatta_handle_transport_fsm(shellmatta_transport_layer_
         crc32           = 0u;
         payloadCounter  = 0u;
         crcCounter      = 0u;
-        transportLayer->active = false;
+        transportLayerInst.active = false;
         memset(payloadBuffer, 0, SHELLMATTA_PAYLOAD_MAXLENGTH + 1);
         break;
     

src/shellmatta_transport.h

@@ -25,6 +25,7 @@
 #define SHELLMATTA_PAYLOAD_LEN_BUFSIZE_RES  ((uint8_t)(1))
 
 /* header field length defines */
+#define SHELLMATTA_HEADER_LENGTH            ((uint8_t)(8))
 /** @brief length of headerfield: start of header */
 #define SHELLMATTA_LENGTH_SOH               ((uint8_t)(1))
 /** @brief length of headerfield: protocol version */
@@ -102,8 +103,10 @@ extern char payloadBuffer[SHELLMATTA_PAYLOAD_MAXLENGTH + 1];
 
 extern shellmatta_transport_layer_t transportLayerInst;
 
+shellmatta_retCode_t shellmatta_reset_transport();
+
 shellmatta_retCode_t shellmatta_init_transport_inst();
 
-shellmatta_retCode_t shellmatta_handle_transport_fsm(shellmatta_transport_layer_t *transportLayer, char *data);
+shellmatta_retCode_t shellmatta_handle_transport_fsm(char *data);
 
 #endif /* _SHELLMATTA_TRANSPORT_H_ */