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59 lines
1.9 KiB
Groff
59 lines
1.9 KiB
Groff
.TH socket_fastopen_connect4 3
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.SH NAME
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socket_fastopen_connect4 \- make a TCP connection and send some data
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.SH SYNTAX
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.B #include <libowfat/socket.h>
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ssize_t \fBsocket_fastopen_connect4\fP(int \fIs\fR,const char \fIip\fR[4],uint16 \fIport\fR,
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const char* \fIbuf\fR,size_t \fIlen\fR);
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.SH DESCRIPTION
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socket_fastopen_connect4 attempts to make a connection from TCP socket \fIs\fR to
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TCP port \fIport\fR on IP address \fIip\fR. If that succeeds, it
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attempts to send \fIlen\fR bytes from \fIbuf\fR.
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The difference to calling socket_connect4 followed by write is that, on
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platforms supporting TCP Fast Open, socket_fastopen_connect4 will send
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the first data packet in the third packet of the TCP handshake, saving
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one useless ACK packet in network traffic.
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This is only useful for protocols where the client sends the first
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bytes.
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socket_connect4 may return
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.sp 1
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.IP \(bu
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>=0, to indicate that the connection succeeded and this many bytes were
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sent.
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.IP \(bu
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-1, setting errno to error_inprogress or error_wouldblock, to indicate
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that the socket is non-blocking
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.IP \(bu
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-1, setting errno to something else, to indicate that the connection
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failed (and failed immediately, if the socket is non-blocking).
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.PP
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When a background connection succeeds or fails, \fIs\fR becomes
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writable; you can use socket_connected to see whether the connection
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succeeded. If the connection failed, socket_connected returns 0,
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setting errno appropriately.
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Once a TCP socket is connected, you can use the read and write
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system calls to transmit data.
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You can call socket_connect4 without calling socket_bind4. This has the
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effect as first calling socket_bind4 with IP address 0.0.0.0 and port 0.
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.SH EXAMPLE
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#include <libowfat/socket.h>
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int \fIs\fR;
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char \fIip\fR[4];
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uint16 \fIp\fR;
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\fIs\fR = socket_tcp4();
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socket_bind4(s,ip,p);
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socket_fastopen_connect4(s,ip,p,"hello",5);
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.SH "SEE ALSO"
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socket_connect4(3), socket_fastopen_connect6(3), socket_fastopen(3)
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