---
name: "DOMAIN_SET"
section: "9freebsd"
platform: "linux"
package: "freebsd-manpages"
version: "12.2-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/DOMAIN_SET/9freebsd"
---

# DOMAIN\_SET(9freebsd)

network domain management

## NAME

**domain\_add**, **pfctlinput**, **pfctlinput2**, **pffinddomain**, **pffindproto**, **pffindtype**, **DOMAIN\_SET** – network domain management

## SYNOPSIS

**#include \<sys/param.h\>**

**#include \<sys/kernel.h\>**

**#include \<sys/protosw.h\>**

**#include \<sys/domain.h\>**

*void*\

**domain\_add**(*void \*data*);

*void*\

**pfctlinput**(*int cmd*, *struct sockaddr \*sa*);

*void*\

**pfctlinput2**(*int cmd*, *struct sockaddr \*sa*, *void \*ctlparam*);

*struct* *domain* *\**\

**pffinddomain**(*int family*);

*struct* *protosw* *\**\

**pffindproto**(*int family*, *int protocol*, *int type*);

*struct* *protosw* *\**\

**pffindtype**(*int family*, *int type*);

*void*\

**DOMAIN\_SET**(*name*);

## DESCRIPTION

Network protocols installed in the system are maintained within what are called domains (for example the *inetdomain* and *localdomain*).

```
struct domain {
	int	dom_family;		/* AF_xxx */
	char	*dom_name;
	void	(*dom_init)		/* initialize domain data structures */
		(void);
	void	(*dom_destroy)		/* cleanup structures / state */
		(void);
	int	(*dom_externalize)	/* externalize access rights */
		(struct mbuf *, struct mbuf **);
	void	(*dom_dispose)		/* dispose of internalized rights */
		(struct mbuf *);
	struct	protosw *dom_protosw, *dom_protoswNPROTOSW;
	struct	domain *dom_next;
	int	(*dom_rtattach)		/* initialize routing table */
		(void **, int);
	int	(*dom_rtdetach)		/* clean up routing table */
		(void **, int);
	void	*(*dom_ifattach)(struct ifnet *);
	void	(*dom_ifdetach)(struct ifnet *, void *);
	int	(*dom_ifmtu)(struct ifnet *);
					/* af-dependent data on ifnet */
};
```

Each domain contains an array of protocol switch structures (*struct protosw \**), one for each socket type supported.

```
struct protosw {
	short	pr_type;		/* socket type used for */
	struct	domain *pr_domain;	/* domain protocol a member of */
	short	pr_protocol;		/* protocol number */
	short	pr_flags;		/* see below */
/* protocol-protocol hooks */
	pr_input_t *pr_input;		/* input to protocol (from below) */
	pr_output_t *pr_output;		/* output to protocol (from above) */
	pr_ctlinput_t *pr_ctlinput;	/* control input (from below) */
	pr_ctloutput_t *pr_ctloutput;	/* control output (from above) */
/* utility hooks */
	pr_init_t *pr_init;
	pr_fasttimo_t *pr_fasttimo;	/* fast timeout (200ms) */
	pr_slowtimo_t *pr_slowtimo;	/* slow timeout (500ms) */
	pr_drain_t *pr_drain;		/* flush any excess space possible */
	struct	pr_usrreqs *pr_usrreqs;	/* user-protocol hook */
};
```

The following functions handle the registration of a new domain, lookups of specific protocols and protocol types within those domains, and handle control messages from the system.

**pfctlinput**() is called by the system whenever an event occurs that could affect every domain. Examples of those types of events are routing table changes, interface shutdowns or certain ICMP message types. When called, **pfctlinput**() calls the protocol specific **pr\_ctlinput**() function for each protocol in that has defined one, in every domain.

**pfctlinput2**() provides that same functionality of **pfctlinput**(), but with a few additional checks and a new *void \** argument that is passed directly to the protocol's **pr\_ctlinput**() function. Unlike **pfctlinput**(), **pfctlinput2**() verifies that *sa* is not NULL, and that only the protocol families that are the same as *sa* have their **pr\_ctlinput**() function called.

**domain\_add**() adds a new protocol domain to the system. The argument *data* is cast directly to *struct domain \** within the function, but is declared *void \** in order to prevent compiler warnings when new domains are registered with **SYSINIT**(). In most cases **domain\_add**() is not called directly, instead **DOMAIN\_SET**() is used.

If the new domain has defined an initialization routine, it is called by **domain\_add**(); as well, each of the protocols within the domain that have defined an initialization routine will have theirs called.

Once a domain is added it cannot be unloaded. This is because there is no reference counting system in place to determine if there are any active references from sockets within that domain.

**pffinddomain**() finds a domain by family. If the domain cannot be found, NULL is returned.

**pffindtype**() and **pffindproto**() look up a protocol by its number or by its type. In most cases, if the protocol or type cannot be found, NULL is returned, but **pffindproto**() may return the default if the requested type is SOCK\_RAW, a protocol switch type of SOCK\_RAW is found, and the domain has a default raw protocol.

Both functions are called by **socreate**() in order to resolve the protocol for the socket currently being created.

**DOMAIN\_SET**() is a macro that simplifies the registration of a domain via **SYSINIT**(). The code resulting from the macro expects there to be a domain structure named “*name*domain” where *name* is the argument to **DOMAIN\_SET**():

```
struct domain localdomain =
{ AF_LOCAL, "local", unp_init, unp_externalize, unp_dispose,
  localsw, &localsw[sizeof(localsw)/sizeof(localsw[0])] };
DOMAIN_SET(local);
```

## RETURN VALUES

Both **pffindtype**() and **pffindproto**() return a *struct protosw \** for the protocol requested. If the protocol or socket type is not found, NULL is returned. In the case of **pffindproto**(), the default protocol may be returned for SOCK\_RAW types if the domain has a default raw protocol.

## SEE ALSO

[socket(2)](/socket/2.md)

## HISTORY

The functions **domain\_add**(), **pfctlinput**(), **pfctlinput2**(), **pffinddomain**(), **pffindproto**(), **pffindtype**() and **DOMAIN\_SET**() first appeared in FreeBSD 4.4.

## AUTHORS

This manual page was written by Chad David ⟨*davidc@acns.ab.ca*⟩.