Totally untested code:

class IPv4_check { static int mask_bits; static int check_bits;

static int ip_to_int( string x ) { int res; foreach( x/".", string x ) { int p = (int)x; res <<= 8; if( p < 0 || p > 255 || (!p && strlen(x-"0")) ) error("Invalid IP. Offending part: "+x+"\n"); res |= (int)x; } return res; }

//! Supported formats: X.X.X.X/BITS //! FIXME: Add more formats static void create( string format ) { int bits; string base; if( sscanf( format, "%s/%d", base, bits ) != 2 ) // Try others error("Failed to parse format\n"); check_bits = ip_to_int( base ); mask_bits = 0xffffffff&~((1<<(32-check_bits))-1); if( check_bits > 32 || check_bits < 1 ) error("Invalid number of bits in the netmask.\n"); check_bits &= mask_bits; }

//! Check whether or not the specified IP matches this pattern //! Also verifies that the IP is a valid IP int check( string ip ) { return (ip_to_int( ip ) & mask_bits) == check_bits; } }

/ Per Hedbor ()

Previous text:

2003-10-01 11:34: Subject: CIDR parsing code ?

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Hello there,

I am looking forward a CIDR parsing code to check if an accessing IP is belonging to a specific CIDR.

Idealy I'd like something like this :

...

IP_check("192.168.2.0/24")->check("192.168.1.1");

This will return 0 if its doesn't belong to the specified CIDR or 1 it is ok ...

Any clues ?

/Xavier

/ Brevbäraren