RFC 4960 Errata and Issues
draft-ietf-tsvwg-rfc4960-errata-03

amp;0xFF])

   uint32_t crc_c[256] =
   {
   0x00000000UL, 0xF26B8303UL, 0xE13B70F7UL, 0x1350F3F4UL,
   0xC79A971FUL, 0x35F1141CUL, 0x26A1E7E8UL, 0xD4CA64EBUL,
   0x8AD958CFUL, 0x78B2DBCCUL, 0x6BE22838UL, 0x9989AB3BUL,
   0x4D43CFD0UL, 0xBF284CD3UL, 0xAC78BF27UL, 0x5E133C24UL,
   0x105EC76FUL, 0xE235446CUL, 0xF165B798UL, 0x030E349BUL,
   0xD7C45070UL, 0x25AFD373UL, 0x36FF2087UL, 0xC494A384UL,
   0x9A879FA0UL, 0x68EC1CA3UL, 0x7BBCEF57UL, 0x89D76C54UL,
   0x5D1D08BFUL, 0xAF768BBCUL, 0xBC267848UL, 0x4E4DFB4BUL,
   0x20BD8EDEUL, 0xD2D60DDDUL, 0xC186FE29UL, 0x33ED7D2AUL,
   0xE72719C1UL, 0x154C9AC2UL, 0x061C6936UL, 0xF477EA35UL,
   0xAA64D611UL, 0x580F5512UL, 0x4B5FA6E6UL, 0xB93425E5UL,
   0x6DFE410EUL, 0x9F95C20DUL, 0x8CC531F9UL, 0x7EAEB2FAUL,
   0x30E349B1UL, 0xC288CAB2UL, 0xD1D83946UL, 0x23B3BA45UL,
   0xF779DEAEUL, 0x05125DADUL, 0x1642AE59UL, 0xE4292D5AUL,
   0xBA3A117EUL, 0x4851927DUL, 0x5B016189UL, 0xA96AE28AUL,
   0x7DA08661UL, 0x8FCB0562UL, 0x9C9BF696UL, 0x6EF07595UL,
   0x417B1DBCUL, 0xB3109EBFUL, 0xA0406D4BUL, 0x522BEE48UL,
   0x86E18AA3UL, 0x748A09A0UL, 0x67DAFA54UL, 0x95B17957UL,
   0xCBA24573UL, 0x39C9C670UL, 0x2A993584UL, 0xD8F2B687UL,

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   0x0C38D26CUL, 0xFE53516FUL, 0xED03A29BUL, 0x1F682198UL,
   0x5125DAD3UL, 0xA34E59D0UL, 0xB01EAA24UL, 0x42752927UL,
   0x96BF4DCCUL, 0x64D4CECFUL, 0x77843D3BUL, 0x85EFBE38UL,
   0xDBFC821CUL, 0x2997011FUL, 0x3AC7F2EBUL, 0xC8AC71E8UL,
   0x1C661503UL, 0xEE0D9600UL, 0xFD5D65F4UL, 0x0F36E6F7UL,
   0x61C69362UL, 0x93AD1061UL, 0x80FDE395UL, 0x72966096UL,
   0xA65C047DUL, 0x5437877EUL, 0x4767748AUL, 0xB50CF789UL,
   0xEB1FCBADUL, 0x197448AEUL, 0x0A24BB5AUL, 0xF84F3859UL,
   0x2C855CB2UL, 0xDEEEDFB1UL, 0xCDBE2C45UL, 0x3FD5AF46UL,
   0x7198540DUL, 0x83F3D70EUL, 0x90A324FAUL, 0x62C8A7F9UL,
   0xB602C312UL, 0x44694011UL, 0x5739B3E5UL, 0xA55230E6UL,
   0xFB410CC2UL, 0x092A8FC1UL, 0x1A7A7C35UL, 0xE811FF36UL,
   0x3CDB9BDDUL, 0xCEB018DEUL, 0xDDE0EB2AUL, 0x2F8B6829UL,
   0x82F63B78UL, 0x709DB87BUL, 0x63CD4B8FUL, 0x91A6C88CUL,
   0x456CAC67UL, 0xB7072F64UL, 0xA457DC90UL, 0x563C5F93UL,
   0x082F63B7UL, 0xFA44E0B4UL, 0xE9141340UL, 0x1B7F9043UL,
   0xCFB5F4A8UL, 0x3DDE77ABUL, 0x2E8E845FUL, 0xDCE5075CUL,
   0x92A8FC17UL, 0x60C37F14UL, 0x73938CE0UL, 0x81F80FE3UL,
   0x55326B08UL, 0xA759E80BUL, 0xB4091BFFUL, 0x466298FCUL,
   0x1871A4D8UL, 0xEA1A27DBUL, 0xF94AD42FUL, 0x0B21572CUL,
   0xDFEB33C7UL, 0x2D80B0C4UL, 0x3ED04330UL, 0xCCBBC033UL,
   0xA24BB5A6UL, 0x502036A5UL, 0x4370C551UL, 0xB11B4652UL,
   0x65D122B9UL, 0x97BAA1BAUL, 0x84EA524EUL, 0x7681D14DUL,
   0x2892ED69UL, 0xDAF96E6AUL, 0xC9A99D9EUL, 0x3BC21E9DUL,
   0xEF087A76UL, 0x1D63F975UL, 0x0E330A81UL, 0xFC588982UL,
   0xB21572C9UL, 0x407EF1CAUL, 0x532E023EUL, 0xA145813DUL,
   0x758FE5D6UL, 0x87E466D5UL, 0x94B49521UL, 0x66DF1622UL,
   0x38CC2A06UL, 0xCAA7A905UL, 0xD9F75AF1UL, 0x2B9CD9F2UL,
   0xFF56BD19UL, 0x0D3D3E1AUL, 0x1E6DCDEEUL, 0xEC064EEDUL,
   0xC38D26C4UL, 0x31E6A5C7UL, 0x22B65633UL, 0xD0DDD530UL,
   0x0417B1DBUL, 0xF67C32D8UL, 0xE52CC12CUL, 0x1747422FUL,
   0x49547E0BUL, 0xBB3FFD08UL, 0xA86F0EFCUL, 0x5A048DFFUL,
   0x8ECEE914UL, 0x7CA56A17UL, 0x6FF599E3UL, 0x9D9E1AE0UL,
   0xD3D3E1ABUL, 0x21B862A8UL, 0x32E8915CUL, 0xC083125FUL,
   0x144976B4UL, 0xE622F5B7UL, 0xF5720643UL, 0x07198540UL,
   0x590AB964UL, 0xAB613A67UL, 0xB831C993UL, 0x4A5A4A90UL,
   0x9E902E7BUL, 0x6CFBAD78UL, 0x7FAB5E8CUL, 0x8DC0DD8FUL,
   0xE330A81AUL, 0x115B2B19UL, 0x020BD8EDUL, 0xF0605BEEUL,
   0x24AA3F05UL, 0xD6C1BC06UL, 0xC5914FF2UL, 0x37FACCF1UL,
   0x69E9F0D5UL, 0x9B8273D6UL, 0x88D28022UL, 0x7AB90321UL,
   0xAE7367CAUL, 0x5C18E4C9UL, 0x4F48173DUL, 0xBD23943EUL,
   0xF36E6F75UL, 0x0105EC76UL, 0x12551F82UL, 0xE03E9C81UL,
   0x34F4F86AUL, 0xC69F7B69UL, 0xD5CF889DUL, 0x27A40B9EUL,
   0x79B737BAUL, 0x8BDCB4B9UL, 0x988C474DUL, 0x6AE7C44EUL,
   0xBE2DA0A5UL, 0x4C4623A6UL, 0x5F16D052UL, 0xAD7D5351UL,
   };

   #endif

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   ---------
   Old text: (Appendix B)
   ---------

   /* Example of table build routine */

   #include <stdio.h>
   #include <stdlib.h>

   #define OUTPUT_FILE   "crc32cr.h"
   #define CRC32C_POLY    0x1EDC6F41L
   FILE *tf;
   unsigned long
   reflect_32 (unsigned long b)
   {
     int i;
     unsigned long rw = 0L;

     for (i = 0; i < 32; i++){
         if (b & 1)
           rw |= 1 << (31 - i);
         b >>= 1;
     }
     return (rw);
   }

   unsigned long
   build_crc_table (int index)
   {
     int i;
     unsigned long rb;

     rb = reflect_32 (index);

     for (i = 0; i < 8; i++){
         if (rb & 0x80000000L)
          rb = (rb << 1) ^ CRC32C_POLY;
         else
          rb <<= 1;
     }
     return (reflect_32 (rb));
   }

   main ()
   {
     int i;

     printf ("\nGenerating CRC-32c table file <%s>\n",

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     OUTPUT_FILE);
     if ((tf = fopen (OUTPUT_FILE, "w")) == NULL){
         printf ("Unable to open %s\n", OUTPUT_FILE);
         exit (1);
     }
     fprintf (tf, "#ifndef __crc32cr_table_h__\n");
     fprintf (tf, "#define __crc32cr_table_h__\n\n");
     fprintf (tf, "#define CRC32C_POLY 0x%08lX\n",
     CRC32C_POLY);
     fprintf (tf,
     "#define CRC32C(c,d) (c=(c>>8)^crc_c[(c^(d))&0xFF])\n");
     fprintf (tf, "\nunsigned long  crc_c[256] =\n{\n");
     for (i = 0; i < 256; i++){
         fprintf (tf, "0x%08lXL, ", build_crc_table (i));
         if ((i & 3) == 3)
           fprintf (tf, "\n");
     }
     fprintf (tf, "};\n\n#endif\n");

     if (fclose (tf) != 0)
       printf ("Unable to close <%s>." OUTPUT_FILE);
     else
       printf ("\nThe CRC-32c table has been written to <%s>.\n",
         OUTPUT_FILE);
   }

   ---------
   New text: (Appendix B)
   ---------

   /* Example of table build routine */

   #include <stdio.h>
   #include <stdlib.h>

   #define OUTPUT_FILE   "crc32cr.h"
   #define CRC32C_POLY    0x1EDC6F41UL

   static FILE *tf;

   static uint32_t
   reflect_32(uint32_t b)
   {
     int i;
     uint32_t rw = 0UL;

     for (i = 0; i < 32; i++) {
         if (b & 1)

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           rw |= 1 << (31 - i);
         b >>= 1;
     }
     return (rw);
   }

   static uint32_t
   build_crc_table(int index)
   {
     int i;
     uint32_t rb;

     rb = reflect_32(index);

     for (i = 0; i < 8; i++) {
         if (rb & 0x80000000UL)
          rb = (rb << 1) ^ (uint32_t)CRC32C_POLY;
         else
          rb <<= 1;
     }
     return (reflect_32 (rb));
   }

   int
   main (void)
   {
     int i;

     printf("\nGenerating CRC-32c table file <%s>\n",
     OUTPUT_FILE);
     if ((tf = fopen (OUTPUT_FILE, "w")) == NULL) {
         printf ("Unable to open %s\n", OUTPUT_FILE);
         exit (1);
     }
     fprintf(tf, "#ifndef __crc32cr_h__\n");
     fprintf(tf, "#define __crc32cr_h__\n\n");
     fprintf(tf, "#define CRC32C_POLY 0x%08XUL\n",
       (uint32_t)CRC32C_POLY);
     fprintf(tf,
       "#define CRC32C(c,d) (c=(c>>8)^crc_c[(c^(d))&0xFF])\n");
     fprintf(tf, "\nuint32_t crc_c[256] =\n{\n");
     for (i = 0; i < 256; i++) {
         fprintf(tf, "0x%08XUL,", build_crc_table (i));
         if ((i & 3) == 3)
           fprintf(tf, "\n");
         else
           fprintf(tf, " ");
     }

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     fprintf(tf, "};\n\n#endif\n");

     if (fclose (tf) != 0)
       printf("Unable to close <%s>.", OUTPUT_FILE);
     else
       printf("\nThe CRC-32c table has been written to <%s>.\n",
         OUTPUT_FILE);
   }

   ---------
   Old text: (Appendix B)
   ---------

   /* Example of crc insertion */

   #include "crc32cr.h"

   unsigned long
   generate_crc32c(unsigned char *buffer, unsigned int length)
   {
     unsigned int i;
     unsigned long crc32 = ~0L;
     unsigned long result;
     unsigned char byte0,byte1,byte2,byte3;

     for (i = 0; i < length; i++){
         CRC32C(crc32, buffer[i]);
     }

     result = ~crc32;

     /*  result now holds the negated polynomial remainder;
      *  since the table and algorithm is "reflected" [williams95].
      *  That is, result has the same value as if we mapped the message
      *  to a polynomial, computed the host-bit-order polynomial
      *  remainder, performed final negation, then did an end-for-end
      *  bit-reversal.
      *  Note that a 32-bit bit-reversal is identical to four inplace
      *  8-bit reversals followed by an end-for-end byteswap.
      *  In other words, the bytes of each bit are in the right order,
      *  but the bytes have been byteswapped.  So we now do an explicit
      *  byteswap.  On a little-endian machine, this byteswap and
      *  the final ntohl cancel out and could be elided.
      */

     byte0 = result & 0xff;
     byte1 = (result>>8) & 0xff;
     byte2 = (result>>16) & 0xff;

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     byte3 = (result>>24) & 0xff;
     crc32 = ((byte0 << 24) |
              (byte1 << 16) |
              (byte2 << 8)  |
              byte3);
     return ( crc32 );
   }

   int
   insert_crc32(unsigned char *buffer, unsigned int length)
   {
     SCTP_message *message;
     unsigned long crc32;
     message = (SCTP_message *) buffer;
     message->common_header.checksum = 0L;
     crc32 = generate_crc32c(buffer,length);
     /* and insert it into the message */
     message->common_header.checksum = htonl(crc32);
     return 1;
   }

   int
   validate_crc32(unsigned char *buffer, unsigned int length)
   {
     SCTP_message *message;
     unsigned int i;
     unsigned long original_crc32;
     unsigned long crc32 = ~0L;

     /* save and zero checksum */
     message = (SCTP_message *) buffer;
     original_crc32 = ntohl(message->common_header.checksum);
     message->common_header.checksum = 0L;
     crc32 = generate_crc32c(buffer,length);
     return ((original_crc32 == crc32)? 1 : -1);
   }

   ---------
   New text: (Appendix B)
   ---------

   /* Example of crc insertion */

   #include "crc32cr.h"

   unsigned long
   generate_crc32c(unsigned char *buffer, unsigned int length)
   {

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     unsigned int i;
     uint32_t crc32 = 0xffffffffUL;
     uint32_t result;
     uint8_t byte0, byte1, byte2, byte3;

     for (i = 0; i < length; i++) {
         CRC32C(crc32, buffer[i]);
     }

     result = ~crc32;

     /*  result now holds the negated polynomial remainder;
      *  since the table and algorithm is "reflected" [williams95].
      *  That is, result has the same value as if we mapped the message
      *  to a polynomial, computed the host-bit-order polynomial
      *  remainder, performed final negation, then did an end-for-end
      *  bit-reversal.
      *  Note that a 32-bit bit-reversal is identical to four inplace
      *  8-bit reversals followed by an end-for-end byteswap.
      *  In other words, the bytes of each bit are in the right order,
      *  but the bytes have been byteswapped.  So we now do an explicit
      *  byteswap.  On a little-endian machine, this byteswap and
      *  the final ntohl cancel out and could be elided.
      */

     byte0 = result & 0xff;
     byte1 = (result>>8) & 0xff;
     byte2 = (result>>16) & 0xff;
     byte3 = (result>>24) & 0xff;
     crc32 = ((byte0 << 24) |
              (byte1 << 16) |
              (byte2 << 8)  |
              byte3);
     return (crc32);
   }

   int
   insert_crc32(unsigned char *buffer, unsigned int length)
   {
     SCTP_message *message;
     uint32_t crc32;
     message = (SCTP_message *) buffer;
     message->common_header.checksum = 0UL;
     crc32 = generate_crc32c(buffer,length);
     /* and insert it into the message */
     message->common_header.checksum = htonl(crc32);
     return 1;
   }

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   int
   validate_crc32(unsigned char *buffer, unsigned int length)
   {
     SCTP_message *message;
     unsigned int i;
     uint32_t original_crc32;
     uint32_t crc32;

     /* save and zero checksum */
     message = (SCTP_message *)buffer;
     original_crc32 = ntohl(message->common_header.checksum);
     message->common_header.checksum = 0L;
     crc32 = generate_crc32c(buffer, length);
     return ((original_crc32 == crc32)? 1 : -1);
   }

3.46.3.  Solution Description

   The code was changed to use platform independent types.

4.  IANA Considerations

   This document does not require any actions from IANA.

5.  Security Considerations

   This document does not add any security considerations to those given
   in [RFC4960].

6.  Acknowledgments

   The authors wish to thank Pontus Andersson, Eric W.  Biederman,
   Cedric Bonnet, Lionel Morand, Jeff Morriss, Karen E.  E.  Nielsen,
   Tom Petch, Julien Pourtet, and Michael Welzl for their invaluable
   comments.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

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   [RFC4960]  Stewart, R., Ed., "Stream Control Transmission Protocol",
              RFC 4960, DOI 10.17487/RFC4960, September 2007,
              <https://www.rfc-editor.org/info/rfc4960>.

7.2.  Informative References

   [I-D.ietf-tsvwg-ecn-experimentation]
              Black, D., "Relaxing Restrictions on Explicit Congestion
              Notification (ECN) Experimentation", draft-ietf-tsvwg-ecn-
              experimentation-07 (work in progress), October 2017.

   [RFC1122]  Braden, R., Ed., "Requirements for Internet Hosts -
              Communication Layers", STD 3, RFC 1122,
              DOI 10.17487/RFC1122, October 1989,
              <https://www.rfc-editor.org/info/rfc1122>.

   [RFC2960]  Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
              Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
              Zhang, L., and V. Paxson, "Stream Control Transmission
              Protocol", RFC 2960, DOI 10.17487/RFC2960, October 2000,
              <https://www.rfc-editor.org/info/rfc2960>.

   [RFC3168]  Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP",
              RFC 3168, DOI 10.17487/RFC3168, September 2001,
              <https://www.rfc-editor.org/info/rfc3168>.

   [RFC4460]  Stewart, R., Arias-Rodriguez, I., Poon, K., Caro, A., and
              M. Tuexen, "Stream Control Transmission Protocol (SCTP)
              Specification Errata and Issues", RFC 4460,
              DOI 10.17487/RFC4460, April 2006,
              <https://www.rfc-editor.org/info/rfc4460>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <https://www.rfc-editor.org/info/rfc5226>.

   [RFC5681]  Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
              Control", RFC 5681, DOI 10.17487/RFC5681, September 2009,
              <https://www.rfc-editor.org/info/rfc5681>.

   [RFC6096]  Tuexen, M. and R. Stewart, "Stream Control Transmission
              Protocol (SCTP) Chunk Flags Registration", RFC 6096,
              DOI 10.17487/RFC6096, January 2011,
              <https://www.rfc-editor.org/info/rfc6096>.

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   [RFC6298]  Paxson, V., Allman, M., Chu, J., and M. Sargent,
              "Computing TCP's Retransmission Timer", RFC 6298,
              DOI 10.17487/RFC6298, June 2011,
              <https://www.rfc-editor.org/info/rfc6298>.

   [RFC6335]  Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
              Cheshire, "Internet Assigned Numbers Authority (IANA)
              Procedures for the Management of the Service Name and
              Transport Protocol Port Number Registry", BCP 165,
              RFC 6335, DOI 10.17487/RFC6335, August 2011,
              <https://www.rfc-editor.org/info/rfc6335>.

   [RFC7053]  Tuexen, M., Ruengeler, I., and R. Stewart, "SACK-
              IMMEDIATELY Extension for the Stream Control Transmission
              Protocol", RFC 7053, DOI 10.17487/RFC7053, November 2013,
              <https://www.rfc-editor.org/info/rfc7053>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

Authors' Addresses

   Randall R. Stewart
   Netflix, Inc.
   Chapin, SC  29036
   United States

   Email: randall@lakerest.net

   Michael Tuexen
   Muenster University of Applied Sciences
   Stegerwaldstrasse 39
   48565 Steinfurt
   Germany

   Email: tuexen@fh-muenster.de

   Maksim Proshin
   Ericsson
   Kistavaegen 25
   Stockholm  164 80
   Sweden

   Email: mproshin@tieto.mera.ru

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