Sponsored Content
Top Forums Programming How to parse IP range in CIDR format in C Post 302351773 by semash! on Wednesday 9th of September 2009 12:33:28 PM
Old 09-09-2009
How to parse IP range in CIDR format in C

Hello everybody,

I'm coding a network program and i need it to "understand" ip ranges, but i don't know how to make to parse an IP CIDR range, let's say "172.16.10.0/24" to work with the specified IP range.

I've found a program which does it, but i don't understand the code. Here is the function:

Code:
static int parse_iprange(char *p)
{
    char *e;
    u32 ip=0;
    int sh;

    for(sh = 24;; sh -= 8) {
        unsigned long v;

        v = strtoul(p, &e, 10);
        if(p == e || v > 255)
            return 0;

        ip |= v << sh;

        p = e + 1;
        if(*e == '/') {
            v = strtoul(p, &e, 10);
            if(p == e || *e || v > 32)
                return 0;
            if(v) {
                v = 32 - v;
                if(sh > v)
                    return 0;
mask:
                v = ~0 << v;
            }
            scan.start = ip & v;
            scan.end = scan.start - v;
            return 1;
        }

        if(!sh) break;

        v = sh;
        if(!*e)
            goto mask;

        if(*e != '.')
            return 0;

        if(!*p || *p == '*' && !p[1])
            goto mask;
    }

    scan.start = ip;
    scan.end = ip + 1;

    if(*e == '-') {
        u32 end = 0, m = ~0;

        do {
            unsigned long v = strtoul(p, &e, 10);
            if(p == e || v > 255)
                return 0;
            p = e + 1;
            end = end<<8 | v;
            m <<= 8;
        } while(m && *e);

        if(*e)
            return 0;

        end |= ip & m;
        if(end < ip)
            return 0;

        scan.end = end + 1;
        return 1;
    }
    return *e == 0;
}

So, please, can somebody explain me how to do this or at least, what does this function do?

Thanks!
 

9 More Discussions You Might Find Interesting

1. UNIX for Advanced & Expert Users

How to Parse a CSV file into a Different Format

Hi I have a CSV file with me in this format Currency, USD, EUR, USD, 1.00, 1.32, EUR, 0.66, 1.00, How do I transpose the file to get to the format below. currency, currency, rate USD, USD, 1.00 USD, EUR, 1.32 EUR, USD, 0.66 EUR, EUR, 1.00 Thanks for your help We are using... (2 Replies)
Discussion started by: cdesiks
2 Replies

2. Shell Programming and Scripting

Parse a range of data

Hello, I have a file which has a range of date like: 00:00 test 00:01 test2 00:02 test3 00:03 test4 00:04 test5 00:05 test6 Using input (stdin) i would like to parse the data 00:01 to 00:04. The output file should be like this: 00:01 test2 00:02 test3 00:03 test4 00:04 test5 ... (5 Replies)
Discussion started by: BufferExploder
5 Replies

3. Shell Programming and Scripting

how to parse the file in xml format using awk/nawk

Hi All, I have an xml file with the below format. <a>111</a><b>222</b><c>333<c><d><e>123</e><f>234</f><d><e>456</e><f>789</f> output needed is 111,222,333,123,234 111,222,333,456,789 nawk 'BEGIN{FS="<|>"} {print a,b,c,e,f a="" ... (7 Replies)
Discussion started by: natalie23
7 Replies

4. Shell Programming and Scripting

How to parse csv format?

Hi, I have a file with 3 fields in csv format: /tmp/foo/,MODIFY,bar/toto "/tmp/foo, bar/","ATTRIB,ISDIR","toto, tata/foobar"I would like to split fields in order to obtain the following: Line1: /tmp/foo/ MODIFY bar/totoLine2: /tmp/foo, bar/ ATTRIB,ISDIR toto, tata/foobarCan't find my way... (11 Replies)
Discussion started by: chebarbudo
11 Replies

5. Shell Programming and Scripting

Modify a perl line to parse out and output to another format

Hey there... I am looking for a way to take the below contents ( small excerpt) of this file called PTR.csv ptrrecord,0000002e0cc0.homeoffice.anfcorp.com,,10.11.191.62,,,False,62.191.11.10.in-addr.arpa,,302400,default... (6 Replies)
Discussion started by: richsark
6 Replies

6. Shell Programming and Scripting

Parse SQL text and only format first SELECT statement.

Hi Forum. Need your expertise on the following question. I have the following file which I would like to parse, find first block of SELECT statment and concatenate all input fields as 1 field (~ delimited): Old File: SELECT /*+ USE_HASH(CCOMM ICAR IMAP IAS IP IMAS IMPS IAP SPCA) */ ... (5 Replies)
Discussion started by: pchang
5 Replies

7. Shell Programming and Scripting

How to change ip addressing format from CIDR notation to netmask and vice versa?

Hi all, I would appreciate if someone could share how to convert CIDR notation to netmask and vice versa. The value below is just an example. it could be different numbers/ip addresses. Initial Output, let say file1.txt Final Output, let say file2.txt (3 Replies)
Discussion started by: type8code0
3 Replies

8. Shell Programming and Scripting

How to parse this file using awk and output in CSV format?

My source file looks like this: Cust-Number = "101" Cust-Name="Joe" Cust-Town="London" Cust-hobby="tennis" Cust-purchase="200" Cust-Number = "102" Cust-Name="Mary" Cust-Town="Newyork" Cust-hobby="reading" Cust-purchase="125" Now I want to parse this file (leaving out hobby) and... (10 Replies)
Discussion started by: Balav
10 Replies

9. Programming

How to parse .nessus file to get result in human readable format?

Scripting Language: bash shell script, python I want to parse .nessus file in human readable format. If any one have any ideas please help me. (2 Replies)
Discussion started by: sk151993
2 Replies
Lite(3) 						User Contributed Perl Documentation						   Lite(3)

NAME
Net::CIDR::Lite - Perl extension for merging IPv4 or IPv6 CIDR addresses SYNOPSIS
use Net::CIDR::Lite; my $cidr = Net::CIDR::Lite->new; $cidr->add($cidr_address); @cidr_list = $cidr->list; @ip_ranges = $cidr->list_range; DESCRIPTION
Faster alternative to Net::CIDR when merging a large number of CIDR address ranges. Works for IPv4 and IPv6 addresses. METHODS
new() $cidr = Net::CIDR::Lite->new $cidr = Net::CIDR::Lite->new(@args) Creates an object to represent a list of CIDR address ranges. No particular format is set yet; once an add method is called with a IPv4 or IPv6 format, only that format may be added for this cidr object. Any arguments supplied are passed to add_any() (see below). add() $cidr->add($cidr_address) Adds a CIDR address range to the list. add_range() $cidr->add_range($ip_range) Adds a hyphenated IP address range to the list. add_cidr() $cidr1->add_cidr($cidr2) Adds address ranges from one object to another object. add_ip() $cidr->add_ip($ip_address) Adds a single IP address to the list. add_any() $cidr->add_any($cidr_or_range_or_address); Determines format of range or single ip address and calls add(), add_range(), add_cidr(), or add_ip() as appropriate. $cidr->clean() $cidr->clean; If you are going to call the list method more than once on the same data, then for optimal performance, you can call this to purge null nodes in overlapping ranges from the list. Boundary nodes in contiguous ranges are automatically purged during add(). Only useful when ranges overlap or when contiguous ranges are added out of order. $cidr->list() @cidr_list = $cidr->list; $list_ref = $cidr->list; Returns a list of the merged CIDR addresses. Returns an array if called in list context, an array reference if not. $cidr->list_range() @cidr_list = $cidr->list_range; $list_ref = $cidr->list_range; Returns a list of the merged addresses, but in hyphenated range format. Returns an array if called in list context, an array reference if not. $cidr->list_short_range() @cidr_list = $cidr->list_short_range; $list_ref = $cidr->list_short_range; Returns a list of the C subnet merged addresses, in short hyphenated range format. Returns an array if called in list context, an array reference if not. Example: 1.1.1.1-2 1.1.1.5-7 1.1.1.254-255 1.1.2.0-2 1.1.3.5 1.1.3.7 $cidr->find() $found = $cidr->find($ip); Returns true if the ip address is found in the CIDR range. False if not. Not extremely efficient, is O(n*log(n)) to sort the ranges in the cidr object O(n) to search through the ranges in the cidr object. The sort is cached on the first call and used in subsequent calls, but if more addresses are added to the cidr object, prep_find() must be called on the cidr object. $cidr->bin_find() Same as find(), but forces a binary search. See also prep_find. $cidr->prep_find() $cidr->prep_find($num); Caches the result of sorting the ip addresses. Implicitly called on the first find call, but must be explicitly called if more addresses are added to the cidr object. find() will do a binary search if the number of ranges is greater than or equal to $num (default 20); $cidr->spanner() $spanner = $cidr1->spanner($label1, $cidr2, $label2, ...); Creates a spanner object to find out if multiple ip addresses are within multiple labeled address ranges. May also be called as (with or without any arguments): Net::CIDR::Lite::Span->new($cidr1, $label1, $cidr2, $label2, ...); $spanner->add() $spanner->add($cidr1, $label1, $cidr2, $label2,...); Adds labeled address ranges to the spanner object. The 'address range' may be a Net::CIDR::Lite object, a single CIDR address range, a single hyphenated IP address range, or a single IP address. $spanner->find() $href = $spanner->find(@ip_addresses); Look up which range(s) ip addresses are in, and return a lookup table of the results, with the keys being the ip addresses, and the value a hash reference of which address ranges the ip address is in. $spanner->bin_find() Same as find(), but forces a binary search. See also prep_find. $spanner->prep_find() $spanner->prep_find($num); Called implicitly the first time $spanner->find(..) is called, must be called again if more cidr objects are added to the spanner object. Will do a binary search if ratio of the number of ip addresses to the number of ranges is less than $num percent (default 4). $spanner->clean() $clean_address = $spanner->clean($ip_address); Validates and returns a cleaned up version of an ip address (which is what you will find as the key in the result from the $spanner->find(..), not necessarily what the original argument looked like). E.g. removes unnecessary leading zeros, removes null blocks from IPv6 addresses, etc. CAVEATS
Garbage in/garbage out. This module does do validation, but maybe not enough to suit your needs. AUTHOR
Douglas Wilson, <dougw@cpan.org> w/numerous hints and ideas borrowed from Tye McQueen. COPYRIGHT
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. SEE ALSO
Net::CIDR. perl v5.18.2 2010-03-25 Lite(3)
All times are GMT -4. The time now is 11:00 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy