Internet/IP address functions

The following functions manipulate IP network and/or host addresses; most take inet style argument(s). This is an IPv4 or IPv6 address string, optionally followed by a netmask.

For IPv4, the format is dotted-decimal, i.e. $N$[.$N$[.$[N$.$N$]]] where $N$ is a decimal, octal or hexadecimal integer from 0 to 255. If $x < 4$ values of $N$ are given, the last $N$ is taken as the last $5-x$ bytes instead of 1 byte, with missing bytes padded to the right. E.g. 192.258 is valid and equivalent to 192.1.2.0: the last $N$ is 2 bytes in size, and covers 5 - 2 = 3 needed bytes, including 1 zero pad to the right. Conversely, 192.168.4.1027 is not valid: the last $N$ is too large.

An IPv4 address may optionally be followed by a netmask, either of the form /$B$ or :$IPv4$, where $B$ is a decimal, octal or hexadecimal netmask integer from 0 to 32, and $IPv4$ is a dotted-decimal IPv4 address of the same format described above. If an :$IPv4$ netmask is given, only the largest contiguous set of most-significant 1 bits are used (because netmasks are contiguous). If no netmask is given, it will be calculated from standard IPv4 class A/B/C/D/E rules, but will be large enough to include all given bytes of the IP. E.g. 1.2.3.4 is Class A which has a netmask of 8, but the netmask will be extended to 32 to include all 4 given bytes.

In version 8 and later, IPv6 addresses are supported as well. These are given in standard IPv6 hex format, i.e. $H$:$H$:$H$:$H$ where $H$ is a 16-bit hexadecimal number, with :: supported for a single span of zero bits, as per canonical IPv6 text representation.

An IPv6 address may optionally be followed by a netmask, of the form /$B$, where $B$ is a decimal, octal or hexadecimal netmask integer from 0 to 128. If no netmask is given, it defaults to the host-only network (i.e. 128).

In version 7.07.1554395000 20190404 and later, error messages are reported.

The inet functions were added in version 5.01.1113268256 of Apr 11 2005 and include the following. See also the Vortex <urlutil> equivalents:

• inetabbrev(inet)

  Returns a possibly shorter-than-canonical representation of $inet, where trailing zero byte(s) of an IPv4 address may be omitted. All bytes of the network, and leading non-zero bytes of the host, will be included. E.g. <urlutil inetabbrev "192.100.0.0/24"> returns 192.100.0/24. The /$B$ netmask is included, except if (in version 7.07.1554840000 20190409 and later) the network is host-only (i.e. netmask is the full size of the IP address). Empty string is returned on error.

• inetcanon(inet)

  Returns canonical representation of $inet. For IPv4, this is dotted-decimal with all 4 bytes. For IPv6, this is 8 16-bit hexadecimal integers (no leading zeroes), colon-separated, possibly with a :: for zero bits. The /$B$ netmask is included, except if (in version 7.07.1554840000 20190409 and later) the network is host-only (i.e. netmask is the full size of the IP address). Empty string is returned on error.

• inetnetwork(inet) Returns string IP address with the network bits of inet, and the host bits set to 0. Empty string is returned on error.

• inethost(inet) Returns string IP address with the host bits of inet, and the network bits set to 0. Empty string is returned on error.

• inetbroadcast(inet) Returns string IP broadcast address for inet, i.e. with the network bits, and host bits set to 1. Empty string is returned on error.

• inetnetmask(inet) Returns string IP netmask for inet, i.e. with the network bits set to 1, and host bits set to 0. Empty string is returned on error.

• inetnetmasklen(inet) Returns integer netmask length of inet. -1 is returned on error.

• inetcontains(inetA, inetB) Returns 1 if inetA contains inetB, i.e. every address in inetB occurs within the inetA network. 0 is returned if not, or -1 on error. Note that an IPv4 address is not considered to be contained within the equivalent IPv4-mapped IPv6 address, nor vice-versa (e.g. ::ffff:1.2.3.4 is considered different from 1.2.3.4). To treat IPv4 addresses the same as their IPv4-mapped IPv6 equivalents, promote both arguments to IPv6 with inetToIPv6() (here).

• inetclass(inet) Returns class of inet, e.g. A, B, C, D, E or classless if a different netmask is used (or the address is IPv6). Empty string is returned on error.

• inet2int(inet)

  Returns integer representation of IP network/host bits of $inet (i.e. without netmask); useful for compact storage of address as integer(s) instead of string. Returns a varint with 1 value for IPv4 addresses, 4 for IPv6 addresses, or 0 values on error (i.e. return compares equal to empty string on error). Note that in version 7 and earlier, a single int was always returned, with -1 for error (or 255.255.255.255).

• int2inet(i) Returns inet string for integer $i taken as an IP address. Since no netmask can be stored in the integer form of an IP address, the returned IP string will not have a netmask. Empty string is returned on error.

• inetToIPv4(inet)

  Converts inet to IPv4 (including netmask), iff IPv4-mapped. Returns the equivalent IPv4 address for inet iff it is an IPv4-mapped IPv6 address; e.g. ::ffff:1.2.3.4 would return 1.2.3.4. Otherwise, returns canonical version of inet iff it is some other IPv6 address; e.g. 2000::a:000b:c:d would return 2000::a:b:c:d. Otherwise returns empty string (i.e. on error). May be useful when storing both IPv4 and IPv6 addresses in a common compact int(4) field from inet2int(), in order to recover original IP family format on display (after int2inet() reconversion). Added in version 8.

• inetToIPv6(inet)

  Converts inet to IPv4-mapped IPv6 (including netmask), iff IPv4. Returns the equivalent IPv4-mapped IPv6 address for inet iff it is IPv4; e.g. 1.2.3.4 would return ::ffff:1.2.3.4. Otherwise, returns canonical version of inet iff it is IPv6; e.g. 2000::a:000b:c:d would return 2000::a:b:c:d. Otherwise returns empty string (i.e. on error). May be useful when storing both IPv4 and IPv6 addresses in a common compact int(4) field from inet2int(), in order to convert potential IPv4 addresses to IPv6 before inet2int() conversion. Added in version 8.

• inetAddressFamily(inet)

  Returns IP address family for inet: IPv4 iff IPv4 address, IPv6 iff IPv6 address, otherwise empty string. Added in version 8.