동적 분기의 구현에 대해서.

#include <stdio.h>
#include <string.h>
 
/* enumeration of all possible conditions */
typedef enum
{
  CASE_1 = 0,
  CASE_2,
  CASE_3,
  NO_CASE
} label_t;
 
/* structure for storing signature & its condition */
typedef struct
{
  char *signature;
  label_t label;
} dynamic_comparison_table_t;
 
/* comparison length */
#define COMPARISON_LENGTH     4
 
/* comparison table (may be in DB) */
const dynamic_comparison_table_t comp_table[] =
{
  {"\x01\x00\x02\x00", CASE_1},
  {"\x02\x01\x00\x00", CASE_2},
  {"\x02\x02\x00\x00", CASE_3}
};
 
/* check if appropriate signature is found */
label_t compare_signature(char *packet)
{
  int i;
 
  for( i = 0; i < sizeof(comp_table)/sizeof(dynamic_comparison_table_t); i++ )
  {
    if( memcmp(comp_table[i].signature, packet, COMPARISON_LENGTH) == 0 )
      return comp_table[i].label;
  }
 
  return NO_CASE;
}
 
/* how to use */
int main(void)
{
   char *packet = "\x01\x00\x02\x00\x11\x22\x33\x44";
 
   /* jump by signature */
   switch( compare_signature(packet) )
   {
     case CASE_1:
       /* blah blah */
       break;
 
     case CASE_2:
       /* blah blah */
       break;
 
     case CASE_3:
       /* blah blah */
       break;
 
     case NO_CASE:
       fprintf(stderr, "ERROR!\n");
       break;
   }
 
   return 0;
}