IP地址转换代码,C代码库,德仔网

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【C】 IP地址转换
作者:Dezai.CN / 发布于2011/2/10/ 656
<div>/* rangeToCidr.c - Convert Ip ranges to CIDR */</div>
<div>/*
modification history
--------------------
01a,17sep08,karn written
*/</div>
<div>/* includes */</div>
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include<math.h>
#include<errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h></div>
<div>/* defines */
//#define DBG
#ifdef DBG
#define DEBUG(x) fprintf(stderr,x)
#else
#define DEBUG
#endif /* DBG */</div>
<div>define IP_BINARY_LENGTH 32+1 /* 32 bits ipv4 address +1 for null */
#define IP_HEX_LENGTH 10 
#define MAX_CIDR_MASK 32
#define MAX_CIDR_LEN 18+1 /*255.255.255.255/32*/</div>
<div>/* Forward declaratopms */
void rangeToCidr(uint32_t from ,uint32_t to,
 void (callback)(char *cidrNotation));
int ipToBin(uint32_t ip , char * pOut);</div>
<div>void printNotation(char *cidrNotation);</div>
<div>/* Globals */</div>
<div>
/*******************************************************************************
*
* ipToBin - convert an ipv4 address to binary representation 
* and pads zeros to the beginning of the string if 
* the length is not 32 
* (Important for ranges like 10.10.0.1 - 20.20.20.20 )
*
* ip - ipv4 address on host order
* pOut - Buffer to store binary.
*
* RETURNS: OK or ERROR 
*/</div>
<div>int ipToBin(uint32_t ip , char * pOut)
 {
 char hex[IP_HEX_LENGTH];
 int i;
 int result=0;
 int len;
 char pTmp[2];
 int tmp;
 /*
 * XXX: Could use bit operations instead but was easier to debug
 */
 char binMap[16][5] = { 
 "0000","0001","0010","0011", "0100",
 "0101","0110","0111","1000", "1001",
 "1010","1011","1100", "1101","1110","1111",
 };
 pTmp[1]=0x0;
 memset(hex,0x0,sizeof(hex));
 len=sprintf(hex,"%x",ip);</div>
<div> for(i=0;i<len;i++)
 {</div>
<div> /* Ugly but to use strtol , we need the last byte as null */
 pTmp[0]=hex[i];</div>
<div> errno = 0;
 tmp = strtol(pTmp, 0x0, 16);</div>
<div> /* Should not happen */
 if (errno != 0)
 {
 memset(pOut,'0',IP_BINARY_LENGTH -1);
 DEBUG ("strtol failed for hex 0x%s\n",pTmp);
 return -1;
 }
<div> result+=sprintf(pOut+result,"%s",binMap[tmp]);
 }
<div> DEBUG("bits %u printed for ip address for hex len %u\n",result,len);
 /* if length is not 32 , pad the start with zeros*/</div>
<div> if(result < IP_BINARY_LENGTH-1)
 {
 char pSwap[IP_BINARY_LENGTH];
 strncpy(pSwap,pOut,IP_BINARY_LENGTH);
 memset(pOut,'0',IP_BINARY_LENGTH);
 strncpy(pOut+IP_BINARY_LENGTH-1-result,pSwap,result);
 DEBUG("corrected length to 32\n");
 }
<div> else if (result > IP_BINARY_LENGTH-1)
 return -1;</div>
<div> /* Success */
 return 0;
 }
<div>/*******************************************************************************
* main : 
* 
* arg1 : Start Ip Address
* arg2 : End Ip address
*/</div>
<div>int main (int argc,char **argv)
 {
 long fromIp, toIp;
 struct in_addr addr;
 if(argc !=3 )
 {
 printf("Usage: %s <from> <to>\n",argv[0]);
 return(0);
 }
<div> /* All operation on host order */ 
 if (inet_aton(argv[1],&addr) == 0)
 goto error;
 fromIp = ntohl(addr.s_addr);</div>
<div> if (inet_aton(argv[2],&addr) ==0)
 goto error;
 toIp = ntohl(addr.s_addr);</div>
<div> rangeToCidr(fromIp,toIp,printNotation);</div>
<div> return 0;
error:
 printf("Invalid Argument\n");
 return -EINVAL;
 }
<div>
/*******************************************************************************
*
* rangeToCidr - convert an ip Range to CIDR, and call 'callback' to handle
* the value. 
*
* from - IP Range start address
* to - IP Range end address
* callback - Callback function to handle cidr.
* RETURNS: OK or ERROR 
*/</div>
<div>void rangeToCidr(uint32_t from ,uint32_t to,
 void (callback)(char *cidrNotation))
 {
 int cidrStart = 0;
 int cidrEnd = MAX_CIDR_MASK - 1;
 long newfrom;
 long mask;
 char fromIp[IP_BINARY_LENGTH];
 char toIp[IP_BINARY_LENGTH];
 struct in_addr addr;
 char cidrNotation[MAX_CIDR_LEN];</div>
<div> memset (fromIp,0x0,sizeof(fromIp));
 memset (toIp,0x0,sizeof(toIp));</div>
<div> if ( ipToBin(from,fromIp) != 0 ) 
 return;
 if ( ipToBin(to,toIp) != 0 )
 return;</div>
<div> DEBUG ("from %lu to %lu\n", from,to);
 DEBUG("from %s\n",fromIp);
 DEBUG("to %s\n",toIp);</div>
<div> if(from < to )
 {</div>
<div> /* Compare the from and to address ranges to get the first
 * point of difference
 */</div>
<div> while(fromIp[cidrStart]==toIp[cidrStart])
 cidrStart ++;
 cidrStart = 32 - cidrStart -1 ;
 DEBUG("cidrStart is %u\n",cidrStart);</div>
<div> /* Starting from the found point of difference make all bits on the 
 * right side zero 
 */</div>
<div> newfrom = from >> cidrStart +1 << cidrStart +1 ;</div>
<div> /* Starting from the end iterate reverse direction to find 
 * cidrEnd
 */ 
 while( fromIp[cidrEnd] == '0' && toIp[cidrEnd] == '1')
 cidrEnd --;</div>
<div> cidrEnd = MAX_CIDR_MASK - 1 - cidrEnd;
 DEBUG("cidrEnd is %u\n",cidrEnd);</div>
<div> if(cidrEnd <= cidrStart)
 {
 /* 
 * Make all the bit-shifted bits equal to 1, for
 * iteration # 1.
 */
 
 mask = pow (2, cidrStart ) - 1;
 DEBUG("it1 is %lu \n",newfrom | mask );
 rangeToCidr (from , newfrom | mask, callback);
 DEBUG("it2 is %lu \n",newfrom | 1 << cidrStart);
 rangeToCidr (newfrom | 1 << cidrStart ,to ,callback);
 }
 else
 {
 addr.s_addr = htonl(newfrom);
 sprintf(cidrNotation,"%s/%d", 
 inet_ntoa(addr), MAX_CIDR_MASK-cidrEnd);
 if (callback != NULL)
 callback(cidrNotation);
 }
 }
<div> else
 {
 addr.s_addr = htonl(from);
 sprintf(cidrNotation,"%s/%d",inet_ntoa(addr),MAX_CIDR_MASK);
 if(callback != NULL)
 callback(cidrNotation);
 }
 }
<div>/*******************************************************************************
*
* printNotation - This is an example callback function to handle cidr notation. 
*
* RETURNS:
*/</div>
<div>void printNotation(char *cidrNotation)
 {
 printf("%s\n",cidrNotation);
 }
</div>
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