minix/man/man4/ip.4

.\"
.\" Copyright 1994 Vrije Universiteit, The Netherlands.
.\" For full copyright and restrictions on use see the file COPYRIGHT in the
.\" top level of the Amoeba distribution.
.\"
.ig
	Software: Philip Homburg, 1991
	Document: Philip Homburg, Sept 3, 1991
	Modified: Greg Sharp and Philip Homburg, March 1992
		  - merged with udp(L) and made a little more complete.
		  Greg Sharp, April 1992
		  - updated keywords for auto index generation
	Modified: Kees J. Bot, June 1994
		  - changed to man(7) format for MINIX 3.
..
.TH IP 4
.SH NAME
ip, eth, psip, udp, tcp \- Internet Protocol server devices and definitions
.SH DESCRIPTION
.de SP
.if t .sp 0.4
.if n .sp
..
The
.BR ip* ,
.BR eth* ,
.BR psip* ,
.BR tcp* ,
and
.B udp*
devices give access to the Internet Protocol (IP) services in MINIX 3.
There can be up to 16 different networks, with 4 network devices each
(a network has either an
.B eth*
or a
.B psip*
device, not both.)
The
.B *
in the device names is a decimal number, so one may see names from
.B ip0
to
.BR ip15 .
A program scanning all networks must try all 16, and not stop if one in
between is missing.  One network is the default network.  Its devices are
linked to names without numbers.
.PP
The
.B eth*
and
.B psip*
devices give direct access to the network packets at the lowest level.
The
.BR ip* ,
.BR tcp* ,
and
.B udp*
devices give access to IP, TCP, or UDP services.
.PP
Most programs that use TCP/IP use code like the following to access the
proper devices:
.PP
.RS
.nf
if ((tcp_device= getenv("TCP_DEVICE")) == NULL)
	tcp_device= "/dev/tcp";
.fi
.RE
.PP
The low level networking programs such as
.BR ifconfig (8)
also have options to select the device they are working with.  The
convention is:
.PP
.RS
.BI ETH_DEVICE= device
.br
.BI -E " device"
.RS
Device to use as raw ethernet device instead of the default /dev/eth.
.RE
.SP
.BI PSIP_DEVICE= device
.br
.BI -P " device"
.RS
Pseudo IP device to use instead of
.BR /dev/psip .
.RE
.SP
.BI IP_DEVICE= device
.br
.BI -I " device"
.RS
IP device to use instead of
.BR /dev/ip .
.RE
.SP
.BI TCP_DEVICE= device
.br
.BI -T " device"
.RS
TCP device to use instead of
.BR /dev/tcp .
.RE
.SP
.BI UDP_DEVICE= device
.br
.BI -U " device"
.RS
UDP device to use instead of
.BR /dev/udp .
.RE
.RE
.SS Programming
Access to the IP services is provided using filedescriptors to open IP
devices.  These open IP channels can be configured with
.BR ioctl (2)
calls, and data can be transferred by calls to
.BR read (2),
and
.BR write (2).
.SS "Types (general)"
.IP <sys/types.h>
.br
Defines
.BR u8_t ,
.BR u16_t ,
.B u32_t
and
.B i32_t
(and
.BR U8_t ,
.BR U16_t ,
.B U32_t
and
.B I32_t
for use in prototypes).
.SS "Types (eth)"
.IP <net/gen/ether.h>
.br
Defines struct ether_addr (\fBether_addr_t\fP) and
.B ether_type_t
and
.B Ether_type_t
for use in prototypes.
.IP <net/gen/eth_io.h>
.br
Defines struct nwio_ethopt (\fBnwio_ethopt_t\fP) and
struct nwio_ethstat (\fBnwio_ethstat_t\fP)
.IP <net/gen/eth_hdr.h>
.br
Defines struct eth_hdr (\fBeth_hdr_t\fP)
.SS "Types (psip)"
.IP <net/gen/psip_hdr.h>
.br
[[[No description available yet.]]]
.IP <net/gen/psip_io.h>
.br
[[[No description available yet.]]]
.SS "Types (ip)"
.IP <net/gen/in.h>
.br
Defines
.BR ipaddr_t ,
.BR ipproto_t
and struct ip_hdropt (\fBip_hdropt_t\fP).
.IP <net/gen/ip_io.h>
.br
Defines struct nwio_ipconf (\fBnwio_ipconf_t\fP) and
struct nwio_ipopt (\fBnwio_ipopt_t\fP)
.IP <net/gen/ip_hdr.h>
.br
Defines struct ip_hdr (\fBip_hdr_t\fP)
.IP <net/gen/route.h>
.br
Defines struct nwio_route (\fBnwio_route_t\fP)
.SS "Types (tcp)"
.IP <net/gen/tcp.h>
.br
Defines
.B tcpport_t
and
.B Tcpport_t
for use in prototypes.
.IP <net/gen/tcp_io.h>
.br
Defines struct nwio_tcpconf (\fBnwio_tcpconf_t\fP),
struct nwio_tcpcl (\fBnwio_tcpcl_t\fP),
struct nwio_tcpatt (\fBnwio_tcpatt_t\fP) and
struct nwio_tcpopt (\fBnwio_tcpopt_t\fP).
.IP <net/gen/tcp_hdr.h>
.br
Defines struct tcp_hdr (\fBtcp_hdr_t\fP) and struct tcp_hdropt
(\fBtcp_hdropt_t\fP).
.SS "Types (udp)"
.IP <net/gen/udp.h>
.br
Defines
.B udpport_t
and
.B Udpport_t
for use in prototypes.
.IP <net/gen/udp_io.h>
.br
Defines struct nwio_udpopt (\fBnwio_udpopt_t\fP).
.IP <net/gen/udp_hdr.h>
.br
Defines struct udp_hdr (\fBudp_hdr_t\fP) and struct udp_io_hdr
(\fBudp_io_hdr_t\fP).
.SS "Byte Order Conversion"
All 16-bit and 32-bit quantities in IP headers must be in network byte
order.  The macros described in
.BR hton (3)
can be used to convert these values to and from the byte order used by
the host machine.
.SS "The Internet Checksum"
The
.B oneC_sum
function (see
.BR oneC_sum (3))
is used to calculate the one's complement checksum needed for IP network
packets.
.SS "General Functions"
.PP
.ft B
\fIfd\fP = open(\fItcpip_device\fP, O_RDWR)
.ft R
.PP
This is how one normally obtains a filedescriptor for a new TCP/IP channel.
.I tcpip_device
names one of the TCP/IP devices.  The channel may be used both to send or to
receive data.
.PP
.ft B
\fIn\fP = read(\fIfd\fP, \fIbuf\fP, \fIsize\fP)
.ft R
.PP
Receives one packet (low level devices) or a number of bytes (TCP stream).
Returns the the number of bytes placed into
.IR buf ,
or returns -1 with an error code placed into
.BR errno .
.PP
.ft B
\fIn\fP = write(\fIfd\fP, \fIbuf\fP, \fIsize\fP)
.ft R
.PP
Sends one packet (low level devices) or a number of bytes (TCP stream).
Returns
.I size
or -1 with the error code placed into
.BR errno .
The TCP/IP
.B read
and
.B write
functions behave like reads and writes on pipes when it comes to signals.
.SS "ETH Functions"
.PP
.ft B
ioctl(\fIfd\fP, NWIOGETHSTAT, &struct nwio_ethstat)
.ft R
.PP
The
.B NWIOGETHSTAT
ioctl
returns the Ethernet address and some statistics of the Ethernet server of
the channel
.IR fd .
The result is returned in the nwio_ethstat structure.
The \fBstruct nwio_ethstat\fP is defined in <net/gen/eth_io.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_ethstat
{
        ether_addr_t nwes_addr;
        eth_stat_t nwes_stat;
} nwio_ethstat_t;
.SP
typedef struct eth_stat
{
    unsigned long ets_recvErr,  /* # receive errors */
	ets_sendErr,            /* # send error */
	ets_OVW,                /* # buffer overwrite warnings,
                                   (packets arrive faster than
                                    can be processed) */
	ets_CRCerr,             /* # crc errors of read */
	ets_frameAll,           /* # frames not aligned (# bits
                                   not a multiple of 8) */
	ets_missedP,            /* # packets missed due to too
                                   slow packet processing */
	ets_packetR,            /* # packets received */
	ets_packetT,            /* # packets transmitted */
	ets_transDef,           /* # transmission deferred (there
                                   was a transmission of an
                                   other station in progress */
	ets_collision,          /* # collisions */
	ets_transAb,            /* # transmissions aborted due
                                   to excessive collisions */
	ets_carrSense,          /* # carrier sense lost */
	ets_fifoUnder,          /* # fifo underruns (processor
                                   is too busy) */
	ets_fifoOver,           /* # fifo overruns (processor is
                                   too busy) */
	ets_CDheartbeat,        /* # times unable to transmit
                                   collision signal */
	ets_OWC;                /* # times out of window
                                   collision */
} eth_stat_t;
.if t .ft R
.fi
.RE
.PP
.ft B
ioctl(\fIfd\fP, NWIOSETHOPT, &struct nwio_ethopt)
.ft R
.PP
Before an Ethernet channel can be used to send or receive
Ethernet packets, it has to be configured using the
.B NWIOSETHOPT
ioctl.
The structure
.B nwio_ethopt
is defined in <net/gen/eth_io.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_ethopt
{
	u32_t nweo_flags;
	ether_addr_t nweo_multi, nweo_rem;
	ether_type_t nweo_type;
} nwio_ethopt_t;
.SP
#define NWEO_NOFLAGS    0x0000L
#define NWEO_ACC_MASK   0x0003L
#       define NWEO_EXCL        0x00000001L
#       define NWEO_SHARED      0x00000002L
#       define NWEO_COPY        0x00000003L
#define NWEO_LOC_MASK   0x0010L
#       define NWEO_EN_LOC      0x00000010L
#       define NWEO_DI_LOC      0x00100000L
#define NWEO_BROAD_MASK 0x0020L
#       define NWEO_EN_BROAD    0x00000020L
#       define NWEO_DI_BROAD    0x00200000L
#define NWEO_MULTI_MASK 0x0040L
#       define NWEO_EN_MULTI    0x00000040L
#       define NWEO_DI_MULTI    0x00400000L
#define NWEO_PROMISC_MASK 0x0080L
#       define NWEO_EN_PROMISC  0x00000080L
#       define NWEO_DI_PROMISC  0x00800000L
#define NWEO_REM_MASK   0x0100L
#       define NWEO_REMSPEC     0x00000100L
#       define NWEO_REMANY      0x01000000L
#define NWEO_TYPE_MASK  0x0200L
#       define NWEO_TYPESPEC    0x00000200L
#       define NWEO_TYPEANY     0x02000000L
#define NWEO_RW_MASK    0x1000L
#       define NWEO_RWDATONLY   0x00001000L
#       define NWEO_RWDATALL    0x10000000L
.if t .ft R
.fi
.RE
.PP
The configuration is divided in a number of section (covered by the xx_MASK
macros).
Options can be set in the
.B nweo_flags
field.
The first section (\fBNWEO_ACC_MASK\fP) controls the access to a certain
Ethernet packet type.
If
.B NWEO_EXCL
is selected then this is the only channel that can send or
receive Ethernet packets of the selected type.
If
.B NWEO_SHARED
is selected then multiple channels (which all have to
select
.BR NWEO_SHARED )
can use the same Ethernet type, they all can send
packets but incoming packets will be delivered to at most one of them.
If
.B NWEO_COPY
is selected then multiple channels have access to the same
Ethernet type and all receive a copy of an incoming packet.
.LP
The
.B NWEO_LOC_MASK
flags control the delivery of packets with a destination
address equal to the Ethernet address of the machine.
If
.B NWEO_EN_LOC
is selected then these packets will be delivered and with
.B NWEO_DI_LOC
they will be discarded.
.PP
.BR NWEO_BROAD_MASK ,
.BR NWEO_MULTI_MASK ,
and
.B NWEO_PROMISC_MASK
do the same to broadcast packets,
multicast packets and promiscuous mode packets as
.B NWEO_LOC_MASK
does for local packets.
Except that the precise multicast address is taken from the \fBnweo_multi\fP
field.
.LP
The
.B NWEO_REM_MASK
flags control whether communication is restricted to
single destination or not.
.B NWEO_REMSPEC
restricts sending and receiving of packets to the single
remote computer specified in the \fBnweo_rem\fP field.
.B NWEO_REMANY
allows sending to and receiving from any remote computer.
.PP
.B NWEO_TYPESPEC
restricts sending and receiving of packets to the type
specified in \fBnweo_type\fP.
The type has to be in network byte order (using
.BR hton (3)).
.B NWEO_TYPEANY
allows any type.
.PP
If the Ethernet header is completely specified by the
.B nweo_flags
i.e., all of
.BR NWEO_EN_LOC ,
.BR NWEO_DI_BROAD ,
.BR NWEO_DI_MULTI ,
.BR NWEO_DI_PROMISC ,
.BR NWEO_REMSPEC
and
.B NWEO_TYPESPEC
are
specified, then
.B NWEO_RWDATONLY
can be used to send and receive only the data part of an Ethernet packet.
If
.B NWEO_RWDATALL
is specified then both Ethernet header and data are used.
.SS "PSIP Functions"
.PP
[[[No description available yet.]]]
.SS "IP Functions"
.PP
.ft B
ioctl(\fIfd\fP, NWIOGIPCONF, &struct nwio_ipconf)
.ft R
.PP
The
.B NWIOGIPCONF
ioctl reports the Internet Address and the netmask.
For the \fInwio_ipconf\fP structure see the \fBNWIOSIPCONF\fP ioctl below.
.PP
.ft B
ioctl(\fIfd\fP, NWIOGIPOROUTE, &struct nwio_route)
.ft R
.PP
The
.B NWIOGIPOROUTE
ioctl can be used to query an IP server about its routing table.
[[[NWIODIPOROUTE, NWIOGIPIROUTE, NWIODIPIROUTE?]]]
The structure \fBnwio_route\fP is defined in <net/gen/route.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_route
{
        u32_t nwr_ent_no;
        u32_t nwr_ent_count;
        ipaddr_t nwr_dest;
        ipaddr_t nwr_netmask;
        ipaddr_t nwr_gateway;
        u32_t nwr_dist;
        u32_t nwr_flags;
        u32_t nwr_pref;
} nwio_route_t;
.SP
#define NWRF_EMPTY      0
#define NWRF_INUSE      1
#define NWRF_FIXED      2
.if t .ft R
.fi
.RE
.PP
The requested entry is taken from \fBnwr_ent_no\fP.
Entries are counted from 0, so the value 0 can be used for an initial query.
The size of the routing table is returned in \fBnwr_ent_count\fP.
The \fBnwr_flags\fP indicates if the entry is in use (\fBNWRF_INUSE\fP) and
if the entry was inserted manually (using \fBNWIOSIPOROUTE\fP) or generated
by the IP server itself.
The route is described by
.BR nwr_dest ,
.BR nwr_netmask ,
.BR nwr_gateway ,
.BR nwr_dist ,
and
.BR nwr_pref .
\fBNwr_dest\fP and \fBnwr_netmask\fP select the destination addresses.
A value of 0.0.0.0 (0x0) in both \fBnwr_dest\fP and \fBnwr_netmask\fP means
every host.
A value of 255.255.255.255 (0xffffffff) in \fBnwr_netmask\fP means a single
host.
Other values of \fBnwr_netmask\fP are netmasks for the network specified
by \fBnwr_dest\fP.
\fBNwr_gateway\fP is gateway that should be used.
\fBNwr_dist\fP is a minimal distance.
Packets with a time to live smaller than \fBnwr_dist\fP will not reach the
destination.
If two routes have equal netmask and distance fields but different
gateways then the gateway with highest value in \fBnwr_pref\fP is used.
.PP
.ft B
ioctl(\fIfd\fP, NWIOSIPCONF, &struct nwio_ipconf)
.ft R
.PP
The
.B NWIOSIPCONF
ioctl can be used to inform the IP server about its Internet Address
and/or its netmask.
Normally an IP server will discover its Internet Address using the RARP
protocol.
.B NWIOSIPCONF
can be used in the case that the RARP failed, or the netmask has to be changed.
Note that higher level protocols (TCP and UDP) assume that the Internet Address
of an IP device does not change, therefore TCP and UDP stop functioning if
the Internet Address is changed.
.PP
The structure \fBnwio_ipconf\fP is defined in <net/gen/ip_io.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_ipconf
{
	u32_t   nwic_flags;
	ipaddr_t nwic_ipaddr;
	ipaddr_t nwic_netmask;
} nwio_ipconf_t;
.SP
#define NWIC_NOFLAGS            0x0
#define NWIC_FLAGS              0x3
#       define NWIC_IPADDR_SET          0x1
#       define NWIC_NETMASK_SET         0x2
.if t .ft R
.fi
.RE
.PP
The function of \fBnwio_ipconf\fP depends on the value of \fBnwic_flags\fP.
If
.B NWIC_IPADDR_SET
is set then the Internet Address will be set to
\fBnwic_ipaddr\fP.
If
.B NWIC_NETMASK_SET
is set then the Internet Address will be set to
\fBnwic_netmask\fP.
.PP
.ft B
ioctl(\fIfd\fP, NWIOSIPOPT, &struct nwio_ipopt)
.ft R
.PP
Before an IP channel can be used, it has to be configured using the
.B NWIOSIPOPT
ioctl.
The structure \fBnwio_ipopt\fP is defined in <net/gen/ip_io.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_ipopt
{
        u32_t nwio_flags;
        ipaddr_t nwio_rem;
        ip_hdropt_t nwio_hdropt;
        u8_t nwio_tos;
        u8_t nwio_ttl;
        u8_t nwio_df;
        ipproto_t nwio_proto;
} nwio_ipopt_t;
.SP
#define NWIO_NOFLAGS    0x0000L
#define NWIO_ACC_MASK   0x0003L
#       define NWIO_EXCL        0x00000001L
#       define NWIO_SHARED      0x00000002L
#       define NWIO_COPY        0x00000003L
#define NWIO_LOC_MASK   0x0010L
#       define NWIO_EN_LOC      0x00000010L
#       define NWIO_DI_LOC      0x00100000L
#define NWIO_BROAD_MASK 0x0020L
#       define NWIO_EN_BROAD    0x00000020L
#       define NWIO_DI_BROAD    0x00200000L
#define NWIO_REM_MASK   0x0100L
#       define NWIO_REMSPEC     0x00000100L
#       define NWIO_REMANY      0x01000000L
#define NWIO_PROTO_MASK 0x0200L
#       define NWIO_PROTOSPEC   0x00000200L
#       define NWIO_PROTOANY    0x02000000L
#define NWIO_HDR_O_MASK 0x0400L
#       define NWIO_HDR_O_SPEC  0x00000400L
#       define NWIO_HDR_O_ANY   0x04000000L
#define NWIO_RW_MASK    0x1000L
#       define NWIO_RWDATONLY   0x00001000L
#       define NWIO_RWDATALL    0x10000000L
.if t .ft R
.fi
.RE
.PP
The options are divided in several categories:
.BR NWIO_ACC_MASK ,
.BR NWIO_LOC_MASK ,
.BR NWIO_BROAD_MASK ,
.BR NWIO_REM_MASK ,
.BR NWIO_PROTO_MASK ,
.B NWIO_HDR_O_MASK
and
.BR NWIO_RW_MASK .
A channel is configured when one option of each category is set.
.PP
The options covered by
.B NWIO_ACC_MASK
control the number of channels that
can use one IP protocol.
If
.B NWIO_EXCL
is specified then only that channel can use a certain IP protocol.
If
.B NWIO_SHARED
then multiple channels that all have to specify
.B NWIO_SHARED
can use the same IP protocol, but incoming packets will
be delivered to a most one channel.
.B NWIO_COPY
does not impose any restrictions.
Every channel gets a copy of an incoming packet.
.PP
.B NWIO_LOC_MASK
and
.B NWIO_BROAD_MASK
control the delivery of packets.
If
.B NWIO_EN_LOC
is specified then packets that are explicitly send to
the IP server are delivered.
If
.B NWIO_EN_BROAD
is specified then broadcast packets are delivered.
Either one or both of them can be disabled with
.B NWIO_DI_LOC
and
.BR NWIO_DI_BROAD .
.PP
.B NWIO_REMSPEC
can be used to restrict communication to one remote host.
This host is taken from the \fBnwio_rem\fP field.
If any remote host is to be allowed then
.B NWIO_REMANY
can be used.
.PP
.B NWIO_PROTOSPEC
restricts communication to one IP protocol, specified
in \fBnwio_proto\fP.
.B NWIO_PROTOANY
allows any protocol to be sent or received.
.PP
.B NWIO_HDR_O_SPEC
specifies all IP header options in advance.
The values are taken from
.BR nwio_hdropt ,
.BR nwio_tos ,
.BR nwio_ttl ,
and
.BR nwio_df .
\fBNwio_hdropt\fP specifies the IP options that should be present in an
outgoing packet.
\fBIp_hdropt_t\fP is defined in <net/gen/in.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct ip_hdropt
{
        u8_t iho_opt_siz;
        u8_t iho_data[IP_MAX_HDR_SIZE-IP_MIN_HDR_SIZE];
} ip_hdropt_t;
.if t .ft R
.fi
.RE
.PP
The bytes of size \fBiho_opt_siz\fP in \fBiho_data\fP are appended to the IP
header.
\fBNwio_tos\fP specifies the value of the ``type of service'' bits,
\fBnwio_ttl\fP gives the value of the ``time to live'' field and \fBnwio_df\fP
specifies whether fragmentation is disallowed or not.
.B NWIO_HDR_O_ANY
specifies that the header options should be specified at
each write request.
.PP
.B NWIO_RWDATONLY
specifies that the header should be omitted from a
write request.
This option can only be used when all header fields are specified in previous
options:
.BR NWIO_EN_LOC ,
.BR NWIO_DI_BROAD ,
.BR NWIO_REMSPEC ,
.B NWIO_PROTOSPEC
and
.BR NWIO_HDR_O_SPEC .
A read operation will also only return the data part, so the IP options will
be lost.
.PP
.ft B
ioctl(\fIfd\fP, NWIOSIPOROUTE, &struct nwio_route)
.ft R
.PP
The
.B NWIOSIPOROUTE
ioctl adds a route to the routing table.
See \fBNWIOGIPOROUTE\fP above for a description of the \fBnwio_route\fP
structure.
The fields \fBnwr_ent_no\fP and \fBnwr_ent_count\fP are ignored.
.SS "TCP Functions"
.PP
.ft B
ioctl(\fIfd\fP, NWIOTCPCONN, &struct nwio_tcpcl)
.ft R
.PP
The
.B NWIOTCPCONN
ioctl tries to setup a connection with a remote TCP/IP server.
The channel must be fully configured (see
.BR NWIOSTCPCONF )
and values for the local port, the remote port and the remote address have be
specified using
.B NWTC_LP_SET
or
.BR NWTC_LP_SEL ,
.B NWTC_SET_RA
and
.BR NWTC_SET_RP .
The struct nwio_tcpcl is defined in <net/gen/tcp_io.h> as:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_tcpcl
{
	long nwtcl_flags;
	long nwtcl_ttl;
} nwio_tcpcl_t;
.if t .ft R
.fi
.RE
.PP
Set the
.B nwtcl_flags
field to zero before the connect or listen call.  [[[Further explanation of
nwio_tcpcl?]]]
.PP
.ft B
ioctl(\fIfd\fP, NWIOGTCPCONF, &struct nwio_tcpconf)
.ft R
.PP
This call reports the current configuration of a TCP channel.
The
.B nwtc_flags
field shows the status of the
.BR access ,
.BR locport ,
.B remaddr
and
.B remport
fields.
.B Nwtc_locaddr
contains the Internet address of the TCP/IP server.
.B Remaddr
contains the Internet address of the remote TCP/IP server when set with
.B NWTC_SET_RA
or after a successful connect or listen (see
.B NWIOTCPCONN
or
.BR NWIOTCPLISTEN ).
.B Nwio_locport
contains the local TCP/IP port set with
.B NWTC_LP_SET
or the selected port set with
.BR NWTC_LP_SEL .
.B Nwtc_remport
contains the TCP port of the remote TCP/IP server as set with
.B NWIO_SET_RP
or after a successful connect or listen.
.PP
A value of 0 (zero) is reported for
.BR nwtc_remaddr ,
.B nwtc_locport
or
.B nwtc_remport
when no value is set either explicitly or implicitly.
.PP
.ft B
ioctl(\fIfd\fP, NWIOTCPLISTEN, &struct nwio_tcpcl)
.ft R
.PP
The
.B NWIOTCPLISTEN
ioctl waits until a remote TCP/IP server tries to connect to this channel.
The channel has to be configured (see
.BR NWIOSTCPCONF ).
An additional restriction is that the local port
must be set (with
.BR NWTC_LP_SET )
or selected (with
.BR NWTC_LP_SEL ).
When a remote address is set only connections for that host are accepted, and
when a remote port is set only connections from that port are accepted.
After a successful listen
.B NWIOGTCPCONF
can be used to find out what the address and port of the other side are.
.PP
.ft B
ioctl(\fIfd\fP, NWIOSTCPCONF, &struct nwio_tcpconf)
.ft R
.PP
Before a TCP channel can be used it must configured using the
.B NWIOSTCPCONF
ioctl.
The parameters to
.B NWIOSTCPCONF
are the channel file descriptor and a
.B struct nwio_tcpconf
as defined in <net/gen/tcp_io.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_tcpconf
{
	u32_t nwtc_flags;
	ipaddr_t nwtc_locaddr;
	ipaddr_t nwtc_remaddr;
	tcpport_t nwtc_locport;
	tcpport_t nwtc_remport;
} nwio_tcpconf_t;
.SP
#define NWTC_NOFLAGS    0x0000L
#define NWTC_ACC_MASK   0x0003L
#       define NWTC_EXCL        0x00000001L
#       define NWTC_SHARED      0x00000002L
#       define NWTC_COPY        0x00000003L
#define NWTC_LOCPORT_MASK       0x0030L
#       define NWTC_LP_UNSET    0x00000010L
#       define NWTC_LP_SET      0x00000020L
#       define NWTC_LP_SEL      0x00000030L
#define NWTC_REMADDR_MASK       0x0100L
#       define NWTC_SET_RA      0x00000100L
#       define NWTC_UNSET_RA    0x01000000L
#define NWTC_REMPORT_MASK       0x0200L
#       define NWTC_SET_RP      0x00000200L
#       define NWTC_UNSET_RP    0x02000000L
.if t .ft R
.fi
.RE
.PP
A tcp channel is considered configured when one flag in each category has
been selected.
Thus one of
.BR NWTC_EXCL ,
.B NWTC_SHARED
or
.BR NWTC_COPY ,
one of
.BR NWTC_LP_UNSET ,
.B NWTC_LP_SET
or
.BR NWTC_LP_SEL ,
one of
.B NWTC_SET_RA
or
.BR NWTC_UNSET_RA ,
and one of
.B NWTC_SET_RP
or
.BR NWTC_UNSET_RP .
.PP
The acc flags control the access to a certain TCP port.
.B NWTC_EXCL
means exclusive access.
An attempt to configure a channel will be denied if the same port is specified
as that of a channel that requested exclusive access.
.B NWTC_SHARED
indicates that several channels use the same port but cooperate.
If the shared mode is specified for one channel than all other channel that
use the same port should also be configured with the
.B NWTC_SHARED
flag.
.B NWTC_COPY
is specified when the programmer does not care about other channels.
This is the default.
.PP
The locport flags control which TCP port is used for communication.
.B NWTC_LP_UNSET
indicates the absence of a local port.
This is the default.
.B NWTC_LP_SET
means that the
.B nwtc_locport
field contains the local port to be used by TCP.
This value must be in network byte order (see
.BR hton (3).)
.B NWTC_LP_SEL
requests the TCP server to pick a port.
This port will be in the range from 32768 to 65535 and will be unique.
.LP
The
.B remaddr
flags specify which hosts are acceptable for connections.
.B NWTC_SET_RA
indicates that only connection to the host specified in
.B nwtc_remaddr
are acceptable.
.B Nwtc_remaddr
should be in network byte order (see
.BR hton (3).)
.B NWTC_UNSET_RA
allows every host on the other side of a connection.
This is the default.
.PP
The
.B remport
flags specify which remote ports are acceptable for connections.
.B NWTC_SET_RP
indicates that only the port specified in
.B nwtc_remport
is acceptable.
.B NWTC_UNSET_RP
allows every port on the other side of a connection.
This is the default.
.PP
.ft B
ioctl(\fIfd\fP, NWIOTCPSHUTDOWN)
.ft R
.PP
The
.B NWIOTCPSHUTDOWN
tells the TCP/IP server that no more data will be sent over the channel
specified by
.IR fd .
This command can be issued when the channel is connected to a remote TCP/IP
server.
The TCP/IP server will tell the remote TCP/IP server and the client of the
remote TCP/IP server will receive an end-of-file indication.
.PP
.ft B
ioctl(\fIfd\fP, NWIOGTCPOPT, &struct nwio_tcpopt)
.br
ioctl(\fIfd\fP, NWIOSTCPOPT, &struct nwio_tcpopt)
.ft R
.PP
The behaviour of a TCP channel may be changed by setting a number of
options.  The TCP options can be obtained with the
.B NWIOGTCPOPT
ioctl and set with the
.B NWIOSTCPOPT
ioctl.  The options are passed in a
.B struct nwio_tcpopt
as defined in <net/gen/tcp_io.h>:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_tcpopt
{
	u32_t nwto_flags;
} nwio_tcpopt_t;
.SP
#define NWTO_NOFLAG     0x0000L
#define NWTO_SND_URG_MASK       0x0001L
#       define NWTO_SND_URG     0x00000001L
#       define NWTO_SND_NOTURG  0x00010000L
#define NWTO_RCV_URG_MASK       0x0002L
#       define NWTO_RCV_URG     0x00000002L
#       define NWTO_RCV_NOTURG  0x00020000L
#define NWTO_BSD_URG_MASK       0x0004L
#       define NWTO_BSD_URG     0x00000004L
#define NWTO_DEL_RST_MASK       0x0008L
#       define NWTO_DEL_RST     0x00000008L
.if t .ft R
.fi
.RE
.PP
The
.B NWTO_SND_URG
option causes bytes written to the channel to be send out as urgent data.
On receiving an
.B EURG
error the
.B NWTO_RCV_URG
option must be set to switch over to reading urgent data.  When all urgent
data has been read an
.B ENOURG
error will follow,
indicating that the option must be cleared with
.BR NWTO_RCV_NOTURG .
Alas the BSD implementation of urgent data disagrees with the RFC's, so to
be BSD compatible one must set the
.B NWTO_BSD_URG
option beforehand on a channel that is to send or receive urgent data.
Given that the BSD implementation is the regarded as the TCP/IP standard one
should always use the BSD style.  The
.B NWTO_DEL_RST
option delays a failure response on a connect to the same port as the
current open connection.  Without this option a connect would fail if
a server is not yet listening.  With this option a connect will linger
on until the server starts listening.  This option is useful for a server
that opens a connection, tells the remote end the local port number and
then listens (FTP), or for a program that forks off servers for incoming
connections (TELNET).  A new connection may come in before a new listen
can be started, so it is nice if the new connect doesn't fail.  Use this
option only when it is clearly needed.
.SS "UDP Functions"
.PP
.ft B
ioctl(\fIfd\fP, NWIOGUDPOPT, &struct nwio_udpopt)
.ft R
.PP
The
.B NWIOGUDPOPT
ioctl returns the current options that result from the default options
and the options set with
.BR NWIOSUDPOPT .
When
.B NWUO_LP_SEL
or
.B NWUO_LP_SET
is selected the local port is returned in
.BR nwuo_locport .
When
.B NWUO_RP_SET
is selected the remote port is returned in
.BR nwuo_remport .
The local address is always returned in
.BR nwuo_locaddr ,
and when
.B NWUO_RA_SET
is selected the remote address is returned in
.BR nwuo_remaddr .
.PP
.ft B
ioctl(\fIfd\fP, NWIOSUDPOPT, &struct nwio_udpopt)
.ft R
.PP
A UDP channel must be configured using the
.B NWIOSUDPOPT
ioctl before any data can be read or written.
.B NWIOSUDPOPT
takes two parameters, a file descriptor to an open UDP device and
pointer to a
.B nwio_udpopt
structure that describes the requested configuration.
The
.B nwio_udpopt
structure is defined in <net/gen/udp_io.h> as:
.PP
.RS
.nf
.if t .ft C
typedef struct nwio_udpopt
{
	unsigned long nwuo_flags;
	udpport_t nwuo_locport;
	udpport_t nwuo_remport;
	ipaddr_t nwuo_locaddr;
	ipaddr_t nwuo_remaddr;
} nwio_udpopt_t;
.SP
#define NWUO_NOFLAGS            0x0000L
#define NWUO_ACC_MASK           0x0003L
#define         NWUO_EXCL               0x00000001L
#define         NWUO_SHARED             0x00000002L
#define         NWUO_COPY               0x00000003L
#define NWUO_LOCPORT_MASK       0x000CL
#define         NWUO_LP_SEL             0x00000004L
#define         NWUO_LP_SET             0x00000008L
#define         NWUO_LP_ANY             0x0000000CL
#define NWUO_LOCADDR_MASK       0x0010L
#define         NWUO_EN_LOC             0x00000010L
#define         NWUO_DI_LOC             0x00100000L
#define NWUO_BROAD_MASK         0x0020L
#define         NWUO_EN_BROAD           0x00000020L
#define         NWUO_DI_BROAD           0x00200000L
#define NWUO_REMPORT_MASK       0x0100L
#define         NWUO_RP_SET             0x00000100L
#define         NWUO_RP_ANY             0x01000000L
#define NWUO_REMADDR_MASK       0x0200L
#define         NWUO_RA_SET             0x00000200L
#define         NWUO_RA_ANY             0x02000000L
#define NWUO_RW_MASK            0x1000L
#define         NWUO_RWDATONLY          0x00001000L
#define         NWUO_RWDATALL           0x10000000L
#define NWUO_IPOPT_MASK         0x2000L
#define         NWUO_EN_IPOPT           0x00002000L
#define         NWUO_DI_IPOPT           0x20000000L
.if t .ft R
.fi
.RE
.PP
A UDP channel is considered configured when one flag in each category has been
selected.
Thus one of
.BR NWUO_EXCL ,
.B NWUO_SHARED
or
.BR NWUO_COPY ,
one of
.BR NWUO_LP_SEL ,
.B NWUO_LP_SET
or
.BR NWUO_LP_ANY ,
one of
.B NWUO_EN_LOC
or
.BR NWUO_DI_LOC ,
one of
.BR NWUO_EN_BROAD ,
or
.BR NWUO_DI_BROAD ,
one of
.BR NWUO_RP_SET ,
or
.BR NWUO_RP_ANY ,
one of
.BR NWUO_RA_SET ,
or
.BR NWUO_RA_ANY ,
one of
.BR NWUO_RWDATONLY ,
or
.BR NWUO_RWDATALL ,
and one of
.BR NWUO_EN_IPOPT ,
or
.BR NWUO_DI_IPOPT .
The acc flags control the access to a certain UDP port.
.B NWUO_EXCL
means exclusive access:
no other channel can use this port.
.B NWUO_SHARED
means shared access:
only channels that specify shared access can use this port
and all packets that are received are handed to at most one channel.
.B NWUO_COPY
imposes no access restriction and all channels get a copy of every received
packet for that port.
.PP
The
.B locport
flags control the selection of the UDP port for this channel.
.B NWUO_LP_SEL
requests the server to pick a port.
This port will be in the range from 32768 to 65535 and it will be unique.
.B NWUO_LP_SET
sets the local port to the value of the
.B nwuo_locport
field.
.B NWUO_LP_ANY
does not select a port.
Reception of data is therefore not possible but it is
possible to send data.
.PP
The
.B locaddr
flags control the reception of packets.
.B NWUO_EN_LOC
enables the reception of packets with the local IP address as destination.
.B NWUO_DI_LOC
disables the reception of packet for the local IP address.
.PP
The
.B broad
flags control the reception of broadcast packets.
.B NWUO_EN_BROAD
enables the reception of broadcast packets and
.B NWUO_DI_BROAD
disables the reception of broadcast packets.
.PP
The
.B remport
flags let the client to specify one specific remote UDP port or
to allow any remote port.
.B NWUO_RP_SET
sets the remote UDP port to the value of
.BR nwuo_remport .
Only packets with a matching remote port will be delivered
and all packets will be sent to that port.
.B NWUO_RP_ANY
allows reception of packets form any port and when transmitting packets the
remote port has to be specified.
.PP
The
.B remaddr
flags control the remote IP address.
.B NWUO_RA_SET
sets the remote IP address the value of
.BR nwuo_remaddr .
Only packets from that address will be delivered and all packets will be sent
to that address.
.B NWUO_RA_ANY
allows reception of packets from any host and when transmitting packets the
remote host has to be specified.
.PP
The
.B rw
flags control the format of the data to be sent or received.
With
.B NWUO_RWDATONLY
only the data part of a UDP packet is sent to the server and only the data
part is received from the server.
The
.B NWUO_RWDATALL
mode presents the data part of a UDP packet with a header that contains
the source and destination IP address, source and destination UDP ports,
the IP options, etc.
The server expects such a header in front of the data to be transmitted.
.ig \" Some for Philip to explain properly:
The header is defined in <net/gen/udp_hdr.h> and looks like this:
.PP
.RS
.nf
.if t .ft C
typedef struct udp_io_hdr
{
	ipaddr_t uih_src_addr;
	ipaddr_t uih_dst_addr;
	udpport_t uih_src_port;
	udpport_t uih_dst_port;
	u16_t uih_ip_opt_len;
	u16_t uih_data_len;
} udp_io_hdr_t;
.if t .ft R
.fi
.RE
.PP
The first four fields are the source and destination IP addresses and
ports.
.B Uih_ip_opt_len
is ???.
.B Uih_data_len
should equal the length of the packet data (packet lenght minus the
header.) ???
..
.PP
The
.B ipopt
flags control the delivery and transmission of IP options.
When
.B NWUO_EN_IPOPT
is set IP, options will be delivered and sent.
When
.B NWUO_DI_IPOPT
is set IP option will be stripped from received packets and no IP options will
be sent.
.ig \" MINIX 3 doesn't have this stuff (yet? ever?)
.SS "UDP Library Functions"
.PP
The following routines provide an somewhat easier to use interface to UDP than
the routines described above (\fBtcpip_open\fP, \fBudp_ioc_setopt\fP,
\fBtcpip_read\fP and \fBtcpip_write\fP).
.LP
.sC
errstat
udp_connect(udp_cap, chan_cap, srcport, dstport, dstaddr, flags)
capability *udp_cap;
capability *chan_cap;
udpport_t srcport;
udpport_t dstport;
ipaddr_t dstaddr;
int flags;
.eC
.kW "\fIudp_connect\fP"
\fIUdp_connect\fP combines the functionality of \fItcpip_open\fP and
\fIudp_ioc_setopt\fP.
A pointer to a UDP server capability should be passed in \fIudp_cap\fP, and
the channel capability will be returned in the capability pointed to by
\fIchan_cap\fP.
If \fIsrcport\fP is 0 then an unused port will be selected, otherwise the local
port will be set to \fIsrcport\fP.
If \fIdstport\fP is non-zero then communication will be restricted to remote ports
that equal to \fIdstport\fP, otherwise any data can be sent to or received from
any remote port.
The same thing applies to \fIdstaddr\fP; if \fIdstaddr\fP is non-zero then
only \fIdstaddr\fP can be reached.
Currently no flags are defined so \fIflags\fP should be 0.
.sH
udp_reconnect
.LP
.sC
errstat
udp_reconnect(chan_cap, srcport, dstport, dstaddr, flags)
capability *chan_cap;
udpport_t srcport;
udpport_t dstport;
ipaddr_t dstaddr;
int flags;
.eC
.kW "\fIudp_reconnect\fP"
\fIUdp_reconnect\fP is the same as \fIudp_connect\fP except that an existing
channel capability is (re)used.
.sH
udp_read_msg
.LP
.sC
errstat
udp_read_msg(chan_cap, msg, msglen, actlen, flags)
capability *chan_cap;
char *msg;
int msglen;
int *actlen;
int flags;
.eC
.kW "\fIudp_read_msg\fP"
\fIUdp_read_msg\fP delivers a UDP packet.
The data part of the UDP packet is
prepended with an \fIudp_io_hdr\fP.
The actual length of the possibly truncated packet is returned in \fIactlen\fP.
No flags are defined so \fIflags\fP should be 0.
.sH
udp_write_msg
.LP
.sC
errstat
udp_write_msg(chan_cap, msg, msglen, flags)
capability *chan_cap;
char *msg;
int msglen;
int flags;
.eC
.kW "\fIudp_write_msg\fP"
A UDP packet can be sent with \fIudp_write_msg\fP.
\fIMsg\fP should point to a \fIudp_io_hdr\fP followed by the data part of the
UDP packet.
The \fIuih_dst_addr\fP and \fIuih_dst_port\fP fields of the \fIudp_io_hdr\fP
should be filled in if no values are specified in the \fIudp_connect\fP,
or \fIudp_reconnect\fP.
.sH
udp_close
.LP
.sC
errstat
udp_close(chan_cap, flags)
capability *chan_cap;
int flags;
.eC
.kW "\fIudp_close\fP"
\fIUdp_close\fP cleans up the administration kept by the UDP library but does
not destroy the capability.
The function should be used if the capability is passed to another process
and should continue to exist.
No flags are defined so \fIflags\fP should be 0.
.sH
udp_destroy
.LP
.sC
errstat
udp_destroy(chan_cap, flags)
capability *chan_cap;
int flags;
.eC
.kW "\fIudp_destroy\fP"
\fIUdp_destroy\fP not only cleans up the administration kept by the UDP library
but also destroys the channel capability.
..
.SH FILES
.IP /dev/eth* \w'/dev/psip*mmm'u
Raw ethernet.  The numbers in the device names are decimal, so one may see
names from
.B eth0
to
.BR eth15 .

.IP /dev/psip*
First and second Pseudo IP network.
.IP /dev/ip*
IP devices for two ethernets and two Pseudo IP networks.
.IP /dev/tcp*
TCP devices for same four networks.
.IP /dev/udp*
UDP devices.
.IP "/dev/eth, /dev/psip, /dev/ip, /dev/tcp, /dev/udp"
Devices for the default network, links to the devices above.
.B Eth
is only present if ethernet is the default,
.B psip
only for pseudo IP.
.SH "SEE ALSO"
.BR hton (3),
.BR oneC_sum (3),
.BR inet (8),
.BR boot (8).
.SH DIAGNOSTICS
Several errors may be returned by the TCP/IP server.  The error code
is found in the
.B errno
variable if the
.BR read ,
.BR write ,
or
.B ioctl
call returns -1.  The TCP/IP error codes defined in <errno.h> are, among others:
.IP EPACKSIZE 5c
This indicates an attempt to read or write with a buffer that is too
large or too small.
.IP ENOBUFS
The TCP/IP server has insufficient memory to execute the request.
.IP ENOTTY
This indicates an attempt to execute a command the particular server
does not understand.
For example, a
.B NWIOGTCPCONF
on an ETH channel.
.IP EBADMODE
The request is refused because the channel is not fully configured, in the
wrong state or the parameters are invalid.
.IP ENETUNREACH
The destination network is not reachable.
.IP EHOSTUNREACH
The destination host is not reachable.
.IP EISCONN
The channel is already connected so a second request is refused.
.IP EADDRINUSE
This address is in use.
.IP ECONNREFUSED
The connection is refused by the other side.
.IP ECONNRESET
The connection is reset (non-gracefully terminated) by the other side.
.IP ETIMEDOUT
The connection is terminated due to an expired timer.
.IP EURG
Urgent data is present and the current receive mode does not allow urgent data
to be transferred.
.IP ENOURG
No urgent data is present and a request came for urgent data.
.IP ENOTCONN
The request requires a connected channel and the channel is not connected.
.IP ESHUTDOWN
The connection is shut down.
That is, a
.B NWIOTCPSHUTDOWN
has been executed so no more data can be transmitted.
.IP ENOCONN
The connection does not exist.
.IP EGENERIC
A generic error code for extremely weird cases.
.SH AUTHOR
Philip Homburg (philip@cs.vu.nl)

.\"
.\" $PchId: ip.4,v 1.4 2001/01/08 19:58:14 philip Exp $