NAME

     libcidr — CIDR-style IP address manipulation functions

SYNOPSIS

     #include <libcidr.h>
     Library libcidr (-lcidr)

SUMMARY

     libcidr is a C library implementing a variety of functions to manipulate IP addresses and
     netblocks.  It handles both IPv4 and IPv6 networks, will transform them to and from text
     strings in a variety of formats, cram them into and lever them out of in_addr and in6_addr
     structures, and give you all sorts of stats about them.  Functions are provided also to tell
     you a few things about the network any given CIDR block is in, what its parent and child
     networks are, and so on.  If you're really nice, libcidr may even cook you breakfast.

     The primary documentation for libcidr is maintained elsewhere, with a full description of
     the functions, their options, and their return values.  Your installation probably has a
     copy of the reference manual installed somewhere, perhaps in /usr/share/libcidr/docs.
     Documentation is also available on the webpage (see below).  This manpage is provided as a
     quick reference.

DESCRIPTION OF FUNCTIONS

     CIDR *cidr_addr_broadcast(const CIDR *cidr)
           Return a CIDR structure describing the broadcast address of the network represented by
           cidr.

     CIDR *cidr_addr_hostmax(const CIDR *cidr)
           Return a CIDR structure describing the "highest" host in the subnet represented by
           cidr.

     CIDR *cidr_addr_hostmin(const CIDR *cidr)
           Return a CIDR structure describing the "lowest" host in the subnet represented by
           cidr.

     CIDR *cidr_addr_network(const CIDR *cidr)
           Return a CIDR structure describing the network address of the network represented by
           cidr.

     CIDR *cidr_alloc(void)
           Allocate and initialize a CIDR structure.

     int cidr_contains(const CIDR *big, const CIDR *little)
           Determine whether little is a CIDR block entirely contained within the block described
           by big.  Return 0 if so, else non-zero.

     CIDR *cidr_dup(const CIDR *cidr)
           Return a duplicate of cidr.

     int cidr_equals(const CIDR *first, const CIDR *second)
           Determine whether first and second describe the same CIDR block.  Return 0 if they do,
           else non-zero.

     void cidr_free(CIDR *cidr)
           Free the memory used by a CIDR *.

     CIDR *cidr_from_inaddr(const struct in_addr *in)
           Generate a CIDR * based on a struct in_addr.

     CIDR *cidr_from_in6addr(const struct in6_addr *in)
           Generate a CIDR * based on a struct in6_addr.

     CIDR *cidr_from_str(const char *str)
           Parse str and return a CIDR * representing it.

     uint8_t *cidr_get_addr(const CIDR *cidr)
           Return the address in an array of binary octets.

     uint8_t *cidr_get_mask(const CIDR *cidr)
           Return the netmask in an array of binary octets.

     int cidr_get_pflen(const CIDR *cidr)
           Return the length of the netmask prefix of cidr.

     int cidr_get_proto(const CIDR *cidr)
           Return the protocol of an address.

     int cidr_is_v4mapped(const CIDR *addr)
           Checks if an IPv6 address is in the IPv4-mapped range.

     CIDR **cidr_net_subnets(const CIDR *cidr)
           Return a 2-element array of CIDR * 's representing the two immediate subnets of the
           network described by cidr.  That is to say, the two networks, within cidr, which have
           a netmask 1 bit longer.

     CIDR *cidr_net_supernet(const CIDR *cidr)
           Return a CIDR * describing the "parent" network of cidr.  That is, the network with a
           netmask 1 bit shorter, which wholly contains cidr.

     const char *cidr_numaddr(const CIDR *cidr)
           Return a pointer to a static string giving the number of total addresses available in
           the network described by cidr.  Do not attempt to alter or free(3) this string.

     const char *cidr_numaddr_pflen(int pflen)
           Return a pointer to a static string giving the number of total addresses available in
           a network having a prefix length of pflen.  Do not attempt to alter or free(3) this
           string.  You probably don't want to call this function manually often.

     const char *cidr_numhost(const CIDR *cidr)
           Return a pointer to a static string giving the number of addresses available for hosts
           available in the network described by cidr.  Do not attempt to alter or free(3) this
           string.

     const char *cidr_numhost_pflen(int pflen)
           Return a pointer to a static string giving the number of addresses available for hosts
           in a network having a prefix length of pflen.  Do not attempt to alter or free(3) this
           string.  You probably don't want to call this function manually often.

     struct in_addr *cidr_to_inaddr(const CIDR *cidr, struct in_addr *in)
           Fill in a struct in_addr with the address given in cidr.  A user-supplied struct
           in_addr is used if passed in; if a null pointer is passed, a new one will be
           allocated, filled in, and returned.

     struct in6_addr *cidr_to_in6addr(const CIDR *cidr, struct in6_addr *in)
           Fill in a struct in6_addr with the address given in cidr.  A user-supplied struct
           in6_addr is used if passed in; if a null pointer is passed, a new one will be
           allocated, filled in, and returned.

     char *cidr_to_str(const CIDR *cidr, int flags)
           Return a string version of the passed-in cidr, as described by flags.  By default, it
           will print in the standard address form for whatever address family cidr represents,
           followed by a slash, and then the prefix length of the netmask.

     const char *cidr_version(void)
           Return a static string containing version information.

AUTHOR

     libcidr is written and maintained by Matthew Fuller ⟨fullermd@over-yonder.net⟩.  Its home on
     the web is at ⟨http://www.over-yonder.net/~fullermd/projects/libcidr⟩; check there for
     updates and additional documentation.