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

#define boolean char
#define TRUE 1==1
#define FALSE !TRUE
#define NONE 0
#define PORTNR 1
#define IPQUAD 2
#define FQDN 3
#define IPV6 4

int isip(char *s);
boolean isportnumber(char *s);
boolean isipquad(char *s);
boolean isipv6(char *s);
boolean isfqdn(char *s);
boolean isemailaddress(char *s);

char sep='#';

int main(int argc, char *argv[])
{
	int n;
	char s[128];

	if (argc>1) sep=argv[1][0];
	printf("Test the IP detecting stuff. # or ^C to abort.\n\n");

	while (1)
	{
		n=0;
		printf("\nGive a string: ");
		scanf("%s",s);
		if (strcmp(s,"#")==0) exit(0);

		if (isportnumber(s)) n=printf("%s qualifies as a port number.\n",s);
		if (isfqdn(s)) n=printf("%s qualifies as an fqdn.\n",s);
		if (isipquad(s)) n=printf("%s qualifies as an ip quad.\n",s);
		if (isipv6(s)) n=printf("%s qualifies as an IPV6.\n",s);
		if (isemailaddress(s)) n=printf("%s qualifies as an e-mail addres.\n",s);
		if (n==0) printf("%s qualifies as nothing.\n",s);
	}
}


/* See if a string qualifies as a parameter for an IP flag */

int isip(char *s)
{
	if (isportnumber(s)) return(PORTNR);
	if (isipquad(s)) return(IPQUAD);
	if (isfqdn(s)) return(FQDN);
	if (isipv6(s)) return(IPV6);
	return(NONE);
}

/* See if string qualifies as a port  number */
/* an up to five digit decimal number qualifies */

boolean isportnumber(char *s)
{
	int i=0;
	char c;

	while ((c=s[i])!=0 && c!=':' && c!=',')
	{
		if (!isdigit(c) || i>4) return(FALSE);
		i++;
	}
	return(TRUE);
}


/* See if a string qualifies as an ip quad */

/* four nummeric values in the range 0-254,0-254,0-254,0-255
	separated by dots.
	The following ranges are reserved for private networks and
	hence invalid:
	192.168.0.1 through and up to 192.168.255.254
	10.0.0.1 through andd up to 10.255.255.254
	172.16.0.1 through and up to 172.31.255.254

	Also the local hosts: 127.0.0.* and 0.0.0.0 are  invalid */

boolean isipquad(char *s)
{
	int n1,n2,n3,n4,dots;
	long unsigned int ipadr;

	dots=sscanf(s,"%d.%d.%d.%d",&n1,&n2,&n3,&n4);
	if (dots<4) return (FALSE);			/* too few fields */

	if (n1<0 || n2<0 || n3<0 || n4<0) return (FALSE);
	if (n1>254 || n2>254 || n3>254 || n4>255) return (FALSE);

	ipadr=(((unsigned long)n1)<<24)+(((unsigned long)n2)<<16)+
										(((unsigned long)n3)<<8)+(unsigned long)n4;
	if (ipadr==0) return(FALSE);
	if (ipadr>=(192L<<24)+(168L<<16)+1L && ipadr<=(192L<<24)+(168L<<16)+(255L<<8)+254L)
																				return(FALSE);
	if (ipadr>=(10L<<24)+1 && ipadr<=(10L<<24)+(255L<<16)+(255L<<8)+254L)
																				return(FALSE);
	if (ipadr>=(172L<<24)+(16L<<16)+1L && ipadr<=(172L<<24)+(31L<<16)+(255L<<8)+254L)
																				return(FALSE);
	if ((ipadr&0XFFFFFF00L)==(127L<<24)) return(FALSE);
	return (TRUE);
}

/* See if a string qualifies as an ipv6 address */

/*	The separator character (colon in the IP world) is defined in the
	global variable sep, default also a colon in this test program.

	Eight hexadecimal values in the range 0-FFFF separated by a SEP char.
	The string may be encased in square brackets and then the separation
	character is always a colon. (':')
	One or more successive zero values may once be represented by
	two successive separators. F.e. 1234::6789:abcd expands to
	1234:0:0:0:0:0:6789:abcd.

	All zeros is invalid. */

boolean isipv6(char *s)
{
	int i=0,j=0,n1,n2,n3,n4,n5,n6,n7,n8,seps=0,nrseps=0,doubleseppos=0;
	char c,sp,t[40],tt[40];
	boolean encased=FALSE;

/* first see if it is encased */

	if (s[i]=='[') { encased=TRUE; i++; sp=':'; } else sp=sep;


/*	first substitute the separator character by a comma, count them and
	note the position of two successive separators on the fly */

	while (s[i] && i<sizeof(t)-2 && (!encased || s[i]!=']'))
	{
		c=s[i];
		if (c==sp)
		{
			c=',';
			nrseps++;
			if (s[i+1]==sp)
			{
				if (!doubleseppos) doubleseppos=j; else return FALSE;
			}
		}
		i++;
		t[j++]=c;
	}
	t[j]=0;
printf("%s %d %d\n",t,doubleseppos,nrseps);


/* Now expand the string if there is a double separator present */

	if (doubleseppos)
	{
		strcpy(tt,&t[doubleseppos+1]);
		t[doubleseppos]=0;
		for (i=0;i<8-nrseps;i++) strcat(t,",0");
		strcat(t,tt);
	}
	seps=sscanf(t,"%x,%x,%x,%x,%x,%x,%x,%x",&n1,&n2,&n3,&n4,&n5,&n6,&n7,&n8);
	if (seps<8) return (FALSE);			/* too few fields */

	if (doubleseppos) printf("Expands as %s\n",t);

	if ((n1+n2+n3+n4+n5+n6+n7+n8)==0) return (FALSE);

	return (TRUE);
}

/* see if a string qualifies as an fqdn (fully qualified domain name)  */

/* It must contain one or more dots. The dots may not be the first or
	the last character. Two dots may not immidiately follow each other.
	It must consist of the characters a..z, A..Z,, 0..9, '.', '-'.
	The first character must be a letter or a digit. */

boolean isfqdn(char *s)
{
	int i=1;
	char c;
	boolean dot=FALSE;

	if (!isalnum(s[0])) return(FALSE);

	while ((c=s[i])!=0 && c!=',' && c!=':')
	{
		if (c=='.')
		{
			dot=TRUE;
			if (s[i-1]=='.') return(FALSE);
		}
		if (!(isalnum(c) || c=='-' || c=='.')) return(FALSE);
		i++;
	}
	if (s[0]=='.' || s[i-1]=='.') return(FALSE);
	return(dot);
}

/* see if a string qualifies as an email address */

/* It must contain exactly one ampersand character that may not be
	the first or the last character. The part after the ampersand must
	contain at least one dot. A dot may not be the first or the last
	character. Two dots may not immidiately follow each other.
	The ampersand may not be immidiately followed or preceded by a dot.
	It must consist of the characters a..z, A..Z, 0..9, '.', '-', '_', '@'.
	The first character must be a letter.  */

boolean isemailaddress(char *s)
{
	int i=1, ampersand=0;
	char c;
	boolean dot=FALSE;

	if (!isalpha(s[0])) return(FALSE);

	while ((c=s[i])!=0)
	{
		if (c=='@')
		{
			ampersand++;
			if (s[i-1]=='.') return(FALSE);
		}
		if (c=='.' && i>0)
		{
			if (ampersand) dot=TRUE;
			if (s[i-1]=='.' || s[i-1]=='@') return(FALSE);
		}
		if (!(isalnum(c)||c=='-'||c=='.'||c=='_'||c=='@')) return(FALSE);
		i++;
	}
	if (s[0]=='.' || s[i-1]=='.') return(FALSE);
	if (s[0]=='@' || s[i-1]=='@') return(FALSE);

	return (dot && (ampersand==1));
}