netutils.cpp

#include "includes.h"
#include "functions.h"
#include "externs.h"

BOOL PrivateIP(const char *ip)
{	
	if (ip) {
		if (strcmp(ip, "") != 0) {
			char *token, ipbuf[32]; 	
			strncpy(ipbuf, ip, sizeof(ipbuf)); 
			if ((token=strtok(ipbuf, ".")) != NULL) { 
				int ip1 = atoi(token);
				if ((token=strtok(NULL, ".")) != NULL) {
					int ip2 = atoi(token);

					if ((ip1 == 10)									// Class A Private Network
						|| (ip1 == 172 && ip2 > 15 && ip2 < 32)	// Class B Private Network
						|| (ip1 == 192 && ip2 == 168))				// Class C Private Network
						//|| (ip1 == 90 && ip2 == 0))					// Undefined Network Range
						return TRUE;
				}
			}
		}
	}
	return FALSE; 
}

unsigned long ResolveAddress(char *szHost)
{
	unsigned long IP = finet_addr(szHost);
	if (IP==INADDR_NONE) {
		hostent *pHE = fgethostbyname(szHost);
		if (pHE == 0) 
			return INADDR_NONE;
		IP = *((unsigned long *)pHE->h_addr_list[0]);	
	}

	return IP;
}

BOOL FlushDNSCache(void)
{
	BOOL bRet = FALSE;
	if (fDnsFlushResolverCache)
		bRet = fDnsFlushResolverCache();

	return (bRet);
}

BOOL FlushARPCache(void)
{
    char logbuf[LOGLINE];
    PMIB_IPNETTABLE arp = 0;
    ULONG tsize = 0;
	BOOL bRet = TRUE;
	
    DWORD result = fGetIpNetTable(NULL, &tsize, TRUE);
	switch(result) {
	case ERROR_SUCCESS:
		break;
	case ERROR_INSUFFICIENT_BUFFER:
		arp=(PMIB_IPNETTABLE)malloc(tsize);
		memset((LPVOID)arp, 0, tsize);

		if (arp != NULL) {
			if ((result = fGetIpNetTable(arp, &tsize, TRUE)) != ERROR_SUCCESS) {
				sprintf(logbuf,"[FLUSHDNS]: Error getting ARP cache: <%d>.",result);
				bRet = FALSE;
			}
		} else {
			sprintf(logbuf,"[FLUSHDNS]: Unable to allocation ARP cache.");
			bRet = FALSE;
		}
		break;
	case ERROR_NO_DATA:
		sprintf(logbuf,"[FLUSHDNS]: ARP cache is empty.");
		bRet = FALSE;
		break;
	case ERROR_NOT_SUPPORTED:
		sprintf(logbuf,"[FLUSHDNS]: Not supported by this system.");
		bRet = FALSE;
		break;
	default:
		sprintf(logbuf,"[FLUSHDNS]: Error getting ARP cache: <%d>.",result);
		bRet = FALSE;
	}

	if (bRet) {
	    for (unsigned int i = 0; i < arp->dwNumEntries; i++)
			fDeleteIpNetEntry(&arp->table[i]);
	} else
		addlog(logbuf);
	free(arp);

	return (bRet);
}

char *GetIP(SOCKET sock)
{
	static char IP[16];

	SOCKADDR sa;
	int sas = sizeof(sa);
	memset(&sa, 0, sizeof(sa));
	fgetsockname(sock, &sa, &sas);

	sprintf(IP,"%d.%d.%d.%d",(BYTE)sa.sa_data[2], (BYTE)sa.sa_data[3], (BYTE)sa.sa_data[4], (BYTE)sa.sa_data[5]);

	return (IP);
}

// Standard TCP/UDP checksum function.
USHORT checksum(USHORT *buffer, int size)
{
    unsigned long cksum=0;

    while (size > 1) {
        cksum += *buffer++;
        size  -= sizeof(USHORT);   
    }

    if (size)
        cksum += *(UCHAR*)buffer;   

    cksum = (cksum >> 16) + (cksum & 0xffff);
    cksum += (cksum >>16); 

    return (USHORT)(~cksum); 
}

unsigned short in_cksum(unsigned short *addr,int len)
{
	register int sum = 0;
	unsigned short answer = 0;
	register unsigned short *w = addr;
	register int nleft = len;

	while (nleft > 1) {
		sum += *w++;
		nleft -= 2;
	}

	if (nleft == 1) {
		*(u_char *)(&answer) = *(u_char *)w ;
		sum += answer;
	}

	sum = (sum >> 16) + (sum & 0xffff);     /* add hi 16 to low 16 */
	sum += (sum >> 16);                     /* add carry */
	answer = ~sum;                          /* truncate to 16 bits */
	return(answer);
}