9.11. Network Address Functions and Operators

Table 9-31 shows the operators available for the cidr and inet types. The operators <<, <<=, >>, and >>= test for subnet inclusion. They consider only the network parts of the two addresses, ignoring any host part, and determine whether one network part is identical to or a subnet of the other.

Table 9-31. cidr and inet Operators

Operator	Description	Example
`<`	is less than	`inet '192.168.1.5' < inet '192.168.1.6'`
`<=`	is less than or equal	`inet '192.168.1.5' <= inet '192.168.1.5'`
`=`	equals	`inet '192.168.1.5' = inet '192.168.1.5'`
`>=`	is greater or equal	`inet '192.168.1.5' >= inet '192.168.1.5'`
`>`	is greater than	`inet '192.168.1.5' > inet '192.168.1.4'`
`<>`	is not equal	`inet '192.168.1.5' <> inet '192.168.1.4'`
`<<`	is contained within	`inet '192.168.1.5' << inet '192.168.1/24'`
`<<=`	is contained within or equals	`inet '192.168.1/24' <<= inet '192.168.1/24'`
`>>`	contains	`inet '192.168.1/24' >> inet '192.168.1.5'`
`>>=`	contains or equals	`inet '192.168.1/24' >>= inet '192.168.1/24'`
`~`	bitwise NOT	`~ inet '192.168.1.6'`
`&`	bitwise AND	`inet '192.168.1.6' & inet '0.0.0.255'`
`\|`	bitwise OR	`inet '192.168.1.6' \| inet '0.0.0.255'`
`+`	addition	`inet '192.168.1.6' + 25`
`-`	subtraction	`inet '192.168.1.43' - 36`
`-`	subtraction	`inet '192.168.1.43' - inet '192.168.1.19'`

Table 9-32 shows the functions available for use with the cidr and inet types. The host, text, and abbrev functions are primarily intended to offer alternative display formats.

Table 9-32. cidr and inet Functions

Function	Return Type	Description	Example	Result
`abbrev(inet)`	`text`	abbreviated display format as text	`abbrev(inet '10.1.0.0/16')`	`10.1.0.0/16`
`abbrev(cidr)`	`text`	abbreviated display format as text	`abbrev(cidr '10.1.0.0/16')`	`10.1/16`
`broadcast(inet)`	`inet`	broadcast address for network	`broadcast('192.168.1.5/24')`	`192.168.1.255/24`
`family(inet)`	`int`	extract family of address; `4` for IPv4, `6` for IPv6	`family('::1')`	`6`
`host(inet)`	`text`	extract IP address as text	`host('192.168.1.5/24')`	`192.168.1.5`
`hostmask(inet)`	`inet`	construct host mask for network	`hostmask('192.168.23.20/30')`	`0.0.0.3`
`masklen(inet)`	`int`	extract netmask length	`masklen('192.168.1.5/24')`	`24`
`netmask(inet)`	`inet`	construct netmask for network	`netmask('192.168.1.5/24')`	`255.255.255.0`
`network(inet)`	`cidr`	extract network part of address	`network('192.168.1.5/24')`	`192.168.1.0/24`
`set_masklen(inet, int)`	`inet`	set netmask length for `inet` value	`set_masklen('192.168.1.5/24', 16)`	`192.168.1.5/16`
`set_masklen(cidr, int)`	`cidr`	set netmask length for `cidr` value	`set_masklen('192.168.1.0/24'::cidr, 16)`	`192.168.0.0/16`
`text(inet)`	`text`	extract IP address and netmask length as text	`text(inet '192.168.1.5')`	`192.168.1.5/32`

Any cidr value can be cast to inet implicitly or explicitly; therefore, the functions shown above as operating on inet also work on cidr values. (Where there are separate functions for inet and cidr, it is because the behavior should be different for the two cases.) Also, it is permitted to cast an inet value to cidr. When this is done, any bits to the right of the netmask are silently zeroed to create a valid cidr value. In addition, you can cast a text value to inet or cidr using normal casting syntax: for example, inet(expression) or colname::cidr.

Table 9-33 shows the functions available for use with the macaddr type. The function trunc(macaddr) returns a MAC address with the last 3 bytes set to zero. This can be used to associate the remaining prefix with a manufacturer.

Table 9-33. macaddr Functions