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icmphdr.c
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Upload User: hepax88
Upload Date: 2007-01-03
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Code Size: 2k
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TCP/IP Stack

Development Platform:

Visual C++

icmphdr.c：Code Content
  1. /* ICMP header conversion routines
  2.  * Copyright 1991 Phil Karn, KA9Q
  3.  */
  4. #include "global.h"
  5. #include "mbuf.h"
  6. #include "internet.h"
  7. #include "ip.h"
  8. #include "icmp.h"
  10. /* Generate ICMP header in network byte order, link data, compute checksum */
  11. void
  12. htonicmp(
  13. struct icmp *icmp,
  14. struct mbuf **bpp
  15. ){
  16. register uint8 *cp;
  17. uint16 checksum;
  19. pushdown(bpp,NULL,ICMPLEN);
  20. cp = (*bpp)->data;
  22. *cp++ = icmp->type;
  23. *cp++ = icmp->code;
  24. cp = put16(cp,0); /* Clear checksum */
  25. switch(icmp->type){
  26. case ICMP_DEST_UNREACH:
  27. if(icmp->code == ICMP_FRAG_NEEDED){
  28. /* Deering/Mogul max MTU indication */
  29. cp = put16(cp,0);
  30. cp = put16(cp,icmp->args.mtu);
  31. } else
  32. cp = put32(cp,0L);
  33. break;
  34. case ICMP_PARAM_PROB:
  35. *cp++ = icmp->args.pointer;
  36. *cp++ = 0;
  37. cp = put16(cp,0);
  38. break;
  39. case ICMP_REDIRECT:
  40. cp = put32(cp,icmp->args.address);
  41. break;
  42. case ICMP_ECHO:
  43. case ICMP_ECHO_REPLY:
  44. case ICMP_TIMESTAMP:
  45. case ICMP_TIME_REPLY:
  46. case ICMP_INFO_RQST:
  47. case ICMP_INFO_REPLY:
  48. cp = put16(cp,icmp->args.echo.id);
  49. cp = put16(cp,icmp->args.echo.seq);
  50. break;
  51. default:
  52. cp = put32(cp,0L);
  53. break;
  54. }
  55. /* Compute checksum, and stash result */
  56. checksum = cksum(NULL,*bpp,len_p(*bpp));
  57. cp = &(*bpp)->data[2];
  58. cp = put16(cp,checksum);
  59. }
  60. /* Pull off ICMP header */
  61. int
  62. ntohicmp(icmp,bpp)
  63. struct icmp *icmp;
  64. struct mbuf **bpp;
  65. {
  66. uint8 icmpbuf[8];
  68. if(icmp == (struct icmp *)NULL)
  69. return -1;
  70. if(pullup(bpp,icmpbuf,8) != 8)
  71. return -1;
  72. icmp->type = icmpbuf[0];
  73. icmp->code = icmpbuf[1];
  74. switch(icmp->type){
  75. case ICMP_DEST_UNREACH:
  76. /* Retrieve Deering/Mogul MTU value */
  77. if(icmp->code == ICMP_FRAG_NEEDED)
  78. icmp->args.mtu = get16(&icmpbuf[6]);
  79. break;
  80. case ICMP_PARAM_PROB:
  81. icmp->args.pointer = icmpbuf[4];
  82. break;
  83. case ICMP_REDIRECT:
  84. icmp->args.address = get32(&icmpbuf[4]);
  85. break;
  86. case ICMP_ECHO:
  87. case ICMP_ECHO_REPLY:
  88. case ICMP_TIMESTAMP:
  89. case ICMP_TIME_REPLY:
  90. case ICMP_INFO_RQST:
  91. case ICMP_INFO_REPLY:
  92. icmp->args.echo.id = get16(&icmpbuf[4]);
  93. icmp->args.echo.seq = get16(&icmpbuf[6]);
  94. break;
  95. }
  96. return 0;
  97. }