ip.4

操作系统设计与实现源码

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_SHARED
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_tcpconf_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