NETINTRO(4) | Device Drivers Manual | NETINTRO(4) |
netintro
—
#include <sys/types.h>
#include <sys/socket.h>
#include <net/route.h>
#include <net/if.h>
All network protocols are associated with a specific protocol family. A protocol family provides basic services to the protocol implementation to allow it to function within a specific network environment. These services may include packet fragmentation and reassembly, routing, addressing, and basic transport. A protocol family may support multiple methods of addressing, though the current protocol implementations do not. A protocol family normally comprises a number of protocols, one per socket(2) type. It is not required that a protocol family support all socket types. A protocol family may contain multiple protocols supporting the same socket abstraction.
A protocol supports one of the socket abstractions detailed in
socket(2). A specific protocol
may be accessed either by creating a socket of the appropriate type and
protocol family, or by requesting the protocol explicitly when creating a
socket. Protocols normally accept only one type of address format, usually
determined by the addressing structure inherent in the design of the
protocol family/network architecture. Certain semantics of the basic socket
abstractions are protocol specific. All protocols are expected to support
the basic model for their particular socket type, but may, in addition,
provide non-standard facilities or extensions to a mechanism. For example, a
protocol supporting the SOCK_STREAM
abstraction may
allow more than one byte of out-of-band data to be transmitted per
out-of-band message.
A network interface is similar to a device interface. Network interfaces comprise the lowest layer of the networking subsystem, interacting with the actual transport hardware. An interface may support one or more protocol families and/or address formats. The SYNOPSIS section of each network interface entry gives a sample specification of the related drivers for use in providing a system description to the config(1) program.
The DIAGNOSTICS section lists messages which may appear on the console and/or in the system error log, /var/log/messages (see syslogd(8)), due to errors in device operation.
struct sockaddr { u_char sa_len; u_char sa_family; char sa_data[14]; };
The field sa_len contains the total length of the of the structure, which may exceed 16 bytes. The following address values for sa_family are known to the system (and additional formats are defined for possible future implementation):
#define AF_LOCAL 1 /* local to host */ #define AF_INET 2 /* internetwork: UDP, TCP, etc. */ #define AF_NS 6 /* Xerox NS protocols */ #define AF_CCITT 10 /* CCITT protocols, X.25 etc */ #define AF_HYLINK 15 /* NSC Hyperchannel */ #define AF_INET6 24 /* internetwork, v6: UDP, TCP, etc. */
A user process (or possibly multiple co-operating processes) maintains this database by sending messages over a special kind of socket. This supplants fixed size ioctl(2) used in earlier releases.
This facility is described in route(4).
The following
ioctl(2) calls may be used to
manipulate network interfaces. The
ioctl(2) is made on a socket
(typically of type SOCK_DGRAM
) in the desired
domain. Most of the requests supported in earlier releases take an
ifreq structure as its parameter. This structure has
the form
struct ifreq { #define IFNAMSIZ 16 char ifr_name[IFNAMSIZ]; /* if name, e.g. "en0" */ union { struct sockaddr ifru_addr; struct sockaddr ifru_dstaddr; struct sockaddr ifru_broadaddr; short ifru_flags; int ifru_metric; void *ifru_data; } ifr_ifru; #define ifr_addr ifr_ifru.ifru_addr /* address */ #define ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-to-p link */ #define ifr_broadaddr ifr_ifru.ifru_broadaddr /* broadcast address */ #define ifr_space ifr_ifru.ifru_space /* sockaddr_storage */ #define ifr_flags ifr_ifru.ifru_flags /* flags */ #define ifr_metric ifr_ifru.ifru_metric /* metric */ #define ifr_mtu ifr_ifru.ifru_mtu /* mtu */ #define ifr_dlt ifr_ifru.ifru_dlt /* data link type (DLT_*) */ #define ifr_value ifr_ifru.ifru_value /* generic value */ #define ifr_media ifr_ifru.ifru_metric /* media options (overload) */ #define ifr_data ifr_ifru.ifru_data /* for use by interface */ #define ifr_buf ifr_ifru.ifru_b.b_buf /* new interface ioctls */ #define ifr_buflen ifr_ifru.ifru_b.b_buflen #define ifr_index ifr_ifru.ifru_value /* interface index */ };
Calls which are now deprecated are:
SIOCSIFADDR
SIOCSIFDSTADDR
SIOCSIFBRDADDR
ioctl(2) requests to obtain addresses and requests both to set and retrieve other data are still fully supported and use the ifreq structure:
SIOCGIFADDR
SIOCGIFDSTADDR
SIOCGIFBRDADDR
SIOCSIFFLAGS
SIOCGIFFLAGS
SIOCSIFMETRIC
SIOCGIFMETRIC
SIOCGIFINDEX
There are two requests that make use of a new structure:
SIOCAIFADDR
SIOCDIFADDR
SIOCGIFALIAS
Request making use of the ifconf structure:
SIOCGIFCONF
/* * Structure used in SIOC[AD]IFADDR request. */ struct ifaliasreq { char ifra_name[IFNAMSIZ]; /* if name, e.g. "en0" */ struct sockaddr ifra_addr; struct sockaddr ifra_dstaddr; #define ifra_broadaddr ifra_dstaddr struct sockaddr ifra_mask; };
/* * Structure used in SIOCGIFCONF request. * Used to retrieve interface configuration * for machine (useful for programs which * must know all networks accessible). */ struct ifconf { int ifc_len; /* size of associated buffer */ union { void *ifcu_buf; struct ifreq *ifcu_req; } ifc_ifcu; #define ifc_buf ifc_ifcu.ifcu_buf /* buffer address */ #define ifc_req ifc_ifcu.ifcu_req /* array of structures returned */ };
netintro
manual appeared in
4.3BSD-Tahoe.
August 2, 2018 | NetBSD 9.4 |