domain (9)
Leading comments
Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice(s), this list of conditions and the following disclaimer as the first lines of this file unmodified other than the possible addition of one or more copyright notices. 2. Redistributions in binary for...
NAME
domain_add pfctlinput pfctlinput2 pffinddomain pffindproto pffindtype DOMAIN_SET - network domain managementSYNOPSIS
In sys/param.h In sys/kernel.h In sys/protosw.h In sys/domain.h Ft void Fn domain_add void *data Ft void Fn pfctlinput int cmd struct sockaddr *sa Ft void Fn pfctlinput2 int cmd struct sockaddr *sa void *ctlparam Ft struct domain * Fn pffinddomain int family Ft struct protosw * Fn pffindproto int family int protocol int type Ft struct protosw * Fn pffindtype int family int type Ft void Fn DOMAIN_SET nameDESCRIPTION
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);
int dom_rtoffset; /* an arg to rtattach, in bits */
int dom_maxrtkey; /* for routing layer */
void *(*dom_ifattach)(struct ifnet *);
void (*dom_ifdetach)(struct ifnet *, void *);
/* af-dependent data on ifnet */
};
Each domain contains an array of protocol switch structures (Vt 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_destroy_t *pr_destroy;
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; /* supersedes pr_usrreq() */
};
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.
Fn 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, Fn pfctlinput calls the protocol specific Fn pr_ctlinput function for each protocol in that has defined one, in every domain.
Fn pfctlinput2 provides that same functionality of Fn pfctlinput , but with a few additional checks and a new Vt void * argument that is passed directly to the protocol's Fn pr_ctlinput function. Unlike Fn pfctlinput , Fn pfctlinput2 verifies that Fa sa is not NULL and that only the protocol families that are the same as Fa sa have their Fn pr_ctlinput function called.
Fn domain_add adds a new protocol domain to the system. The argument Fa data is cast directly to Vt struct domain * within the function, but is declared Vt void * in order to prevent compiler warnings when new domains are registered with Fn SYSINIT . In most cases Fn domain_add is not called directly, instead Fn DOMAIN_SET is used.
If the new domain has defined an initialization routine, it is called by Fn 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.
Fn pffinddomain finds a domain by family. If the domain cannot be found, NULL is returned.
Fn pffindtype and Fn 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 Fn 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 Fn socreate in order to resolve the protocol for the socket currently being created.
Fn DOMAIN_SET is a macro that simplifies the registration of a domain via Fn SYSINIT . The code resulting from the macro expects there to be a domain structure named ``Fa name domain '' where Fa name is the argument to Fn DOMAIN_SET :
struct domain localdomain =
{ AF_LOCAL, "local", unp_init, unp_externalize, unp_dispose,
localsw, &localsw[sizeof(localsw)/sizeof(localsw[0])] };
DOMAIN_SET(local);