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69 lines
1.2 KiB
Groff
69 lines
1.2 KiB
Groff
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.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 /usr/local/plan9/src/lib9/udp.c
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.SH SEE ALSO
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.IR ip (3)
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