10564b1175
groff 1.23.0 added .MR to its -man macro package. The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020." From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.
Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.
Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized. groff's .MR does not. This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.
69 lines
1.2 KiB
Groff
69 lines
1.2 KiB
Groff
.TH UDPREAD 3
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.SH NAME
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udpread, udpwrite \- read and write UDP packets
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.SH SYNOPSIS
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.B #include <u.h>
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.PP
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.B #include <libc.h>
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.PP
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.B #include <ip.h>
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.PP
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.B
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.nf
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.ta +4n +8n
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typedef struct Udphdr Udphdr;
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struct Udphdr
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{
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uchar raddr[IPaddrlen]; /* remote address and port */
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uchar laddr[IPaddrlen]; /* local address and port */
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uchar rport[2];
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uchar lport[2];
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};
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.PP
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.B
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long udpread(int fd, Udphdr *hdr, void *data, long n)
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.PP
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.B
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long udpwrite(int fd, Udphdr *hdr, void *data, long n)
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.SH DESCRIPTION
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.I Udpread
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and
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.I udpwrite
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read and write UDP packets from the UDP network connection
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established on file descriptor
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.IR fd .
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.PP
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.I Udpread
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reads at most
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.I n
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bytes of packet body into
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.I data ,
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stores the header in
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.IR hdr ,
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and returns the number of bytes stored in
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.IR data .
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.PP
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.I Udpwrite
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writes the
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.I n
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bytes stored in
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.I data
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in a UDP packet with header
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.IR hdr .
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.PP
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Note that the
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.B Udphdr
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frames the addresses as local and remote
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instead of source and destination.
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Thus the
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.I hdr
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filled in for a packet read by
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.I udpread
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can be used unchanged in
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.I udpwrite
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to send a response back to the sender of the original packet.
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.SH SOURCE
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.B \*9/src/lib9/udp.c
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.SH SEE ALSO
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.MR ip 3
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