\hypertarget{group__sending-data}{}\section{Sending data}
\label{group__sending-data}\index{Sending data@{Sending data}}
\subsection*{Enumerations}
\begin{DoxyCompactItemize}
\item 
enum \hyperlink{group__sending-data_ga98b099cf8c1c7e38ad78501f270e193d}{lws\+\_\+write\+\_\+protocol} \{ \\*
\hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db}{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT} = 0, 
\hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2}{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY} = 1, 
\hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826}{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+O\+N\+T\+I\+N\+U\+A\+T\+I\+ON} = 2, 
\hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e}{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP} = 3, 
\\*
{\bfseries L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+P\+I\+NG} = 5, 
{\bfseries L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+P\+O\+NG} = 6, 
{\bfseries L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+F\+I\+N\+AL} = 7, 
\hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917}{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+H\+E\+A\+D\+E\+RS} = 8, 
\\*
\hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3}{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+N\+O\+\_\+\+F\+IN} = 0x40, 
\hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce}{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+L\+I\+E\+N\+T\+\_\+\+I\+G\+N\+O\+R\+E\+\_\+\+X\+O\+R\+\_\+\+M\+A\+SK} = 0x80
 \}
\end{DoxyCompactItemize}
\subsection*{Functions}
\begin{DoxyCompactItemize}
\item 
L\+W\+S\+\_\+\+V\+I\+S\+I\+B\+LE L\+W\+S\+\_\+\+E\+X\+T\+E\+RN int \hyperlink{group__sending-data_gafd5fdd285a0e25ba7e3e1051deec1001}{lws\+\_\+write} (struct lws $\ast$wsi, unsigned char $\ast$buf, size\+\_\+t len, enum \hyperlink{group__sending-data_ga98b099cf8c1c7e38ad78501f270e193d}{lws\+\_\+write\+\_\+protocol} protocol)
\end{DoxyCompactItemize}


\subsection{Detailed Description}
A\+P\+Is related to writing data on a connection 

\subsection{Enumeration Type Documentation}
\index{Sending data@{Sending data}!lws\+\_\+write\+\_\+protocol@{lws\+\_\+write\+\_\+protocol}}
\index{lws\+\_\+write\+\_\+protocol@{lws\+\_\+write\+\_\+protocol}!Sending data@{Sending data}}
\subsubsection[{\texorpdfstring{lws\+\_\+write\+\_\+protocol}{lws\_write\_protocol}}]{\setlength{\rightskip}{0pt plus 5cm}enum {\bf lws\+\_\+write\+\_\+protocol}}\hypertarget{group__sending-data_ga98b099cf8c1c7e38ad78501f270e193d}{}\label{group__sending-data_ga98b099cf8c1c7e38ad78501f270e193d}


{\ttfamily \#include $<$\hyperlink{libwebsockets_8h}{lib/libwebsockets.\+h}$>$}

\begin{Desc}
\item[Enumerator]\par
\begin{description}
\index{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT}!Sending data@{Sending data}}\index{Sending data@{Sending data}!L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT}}\item[{\em 
L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT\hypertarget{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db}{}\label{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db}
}]Send a ws T\+E\+XT message,the pointer must have L\+W\+S\+\_\+\+P\+RE valid memory behind it. The receiver expects only valid utf-\/8 in the payload \index{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY}!Sending data@{Sending data}}\index{Sending data@{Sending data}!L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY}}\item[{\em 
L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY\hypertarget{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2}{}\label{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2}
}]Send a ws B\+I\+N\+A\+RY message, the pointer must have L\+W\+S\+\_\+\+P\+RE valid memory behind it. Any sequence of bytes is valid \index{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+O\+N\+T\+I\+N\+U\+A\+T\+I\+ON@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+O\+N\+T\+I\+N\+U\+A\+T\+I\+ON}!Sending data@{Sending data}}\index{Sending data@{Sending data}!L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+O\+N\+T\+I\+N\+U\+A\+T\+I\+ON@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+O\+N\+T\+I\+N\+U\+A\+T\+I\+ON}}\item[{\em 
L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+O\+N\+T\+I\+N\+U\+A\+T\+I\+ON\hypertarget{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826}{}\label{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826}
}]Continue a previous ws message, the pointer must have L\+W\+S\+\_\+\+P\+RE valid memory behind it \index{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP}!Sending data@{Sending data}}\index{Sending data@{Sending data}!L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP}}\item[{\em 
L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP\hypertarget{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e}{}\label{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e}
}]Send H\+T\+TP content \index{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+H\+E\+A\+D\+E\+RS@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+H\+E\+A\+D\+E\+RS}!Sending data@{Sending data}}\index{Sending data@{Sending data}!L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+H\+E\+A\+D\+E\+RS@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+H\+E\+A\+D\+E\+RS}}\item[{\em 
L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+H\+E\+A\+D\+E\+RS\hypertarget{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917}{}\label{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917}
}]Send http headers (http2 encodes this payload and L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP payload differently, http 1.\+x links also handle this correctly. so to be compatible with both in the future,header response part should be sent using this regardless of http version expected) \index{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+N\+O\+\_\+\+F\+IN@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+N\+O\+\_\+\+F\+IN}!Sending data@{Sending data}}\index{Sending data@{Sending data}!L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+N\+O\+\_\+\+F\+IN@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+N\+O\+\_\+\+F\+IN}}\item[{\em 
L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+N\+O\+\_\+\+F\+IN\hypertarget{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3}{}\label{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3}
}]This part of the message is not the end of the message \index{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+L\+I\+E\+N\+T\+\_\+\+I\+G\+N\+O\+R\+E\+\_\+\+X\+O\+R\+\_\+\+M\+A\+SK@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+L\+I\+E\+N\+T\+\_\+\+I\+G\+N\+O\+R\+E\+\_\+\+X\+O\+R\+\_\+\+M\+A\+SK}!Sending data@{Sending data}}\index{Sending data@{Sending data}!L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+L\+I\+E\+N\+T\+\_\+\+I\+G\+N\+O\+R\+E\+\_\+\+X\+O\+R\+\_\+\+M\+A\+SK@{L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+L\+I\+E\+N\+T\+\_\+\+I\+G\+N\+O\+R\+E\+\_\+\+X\+O\+R\+\_\+\+M\+A\+SK}}\item[{\em 
L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+L\+I\+E\+N\+T\+\_\+\+I\+G\+N\+O\+R\+E\+\_\+\+X\+O\+R\+\_\+\+M\+A\+SK\hypertarget{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce}{}\label{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce}
}]client packet payload goes out on wire unmunged only useful for security tests since normal servers cannot decode the content if used \end{description}
\end{Desc}

\begin{DoxyCode}
2959                         \{
2960         \hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db}{LWS\_WRITE\_TEXT}                                            = 0,
2964         \hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2}{LWS\_WRITE\_BINARY}                                        = 1,
2967         \hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826}{LWS\_WRITE\_CONTINUATION}                                    = 2,
2970         \hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e}{LWS\_WRITE\_HTTP}                                            = 3,
2973         \textcolor{comment}{/* LWS\_WRITE\_CLOSE is handled by lws\_close\_reason() */}
2974         LWS\_WRITE\_PING                                          = 5,
2975         LWS\_WRITE\_PONG                                          = 6,
2976 
2977         \textcolor{comment}{/* Same as write\_http but we know this write ends the transaction */}
2978         LWS\_WRITE\_HTTP\_FINAL                                    = 7,
2979 
2980         \textcolor{comment}{/* HTTP2 */}
2981 
2982         \hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917}{LWS\_WRITE\_HTTP\_HEADERS}                                    = 8,
2989         \textcolor{comment}{/****** add new things just above ---^ ******/}
2990 
2991         \textcolor{comment}{/* flags */}
2992 
2993         \hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3}{LWS\_WRITE\_NO\_FIN} = 0x40,
2996         \hyperlink{group__sending-data_gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce}{LWS\_WRITE\_CLIENT\_IGNORE\_XOR\_MASK} = 0x80
3000 \};
\end{DoxyCode}


\subsection{Function Documentation}
\index{Sending data@{Sending data}!lws\+\_\+write@{lws\+\_\+write}}
\index{lws\+\_\+write@{lws\+\_\+write}!Sending data@{Sending data}}
\subsubsection[{\texorpdfstring{lws\+\_\+write(struct lws $\ast$wsi, unsigned char $\ast$buf, size\+\_\+t len, enum lws\+\_\+write\+\_\+protocol protocol)}{lws\_write(struct lws *wsi, unsigned char *buf, size\_t len, enum lws\_write\_protocol protocol)}}]{\setlength{\rightskip}{0pt plus 5cm}L\+W\+S\+\_\+\+V\+I\+S\+I\+B\+LE L\+W\+S\+\_\+\+E\+X\+T\+E\+RN int lws\+\_\+write (
\begin{DoxyParamCaption}
\item[{struct lws $\ast$}]{wsi, }
\item[{unsigned char $\ast$}]{buf, }
\item[{size\+\_\+t}]{len, }
\item[{enum {\bf lws\+\_\+write\+\_\+protocol}}]{protocol}
\end{DoxyParamCaption}
)}\hypertarget{group__sending-data_gafd5fdd285a0e25ba7e3e1051deec1001}{}\label{group__sending-data_gafd5fdd285a0e25ba7e3e1051deec1001}


{\ttfamily \#include $<$\hyperlink{libwebsockets_8h}{lib/libwebsockets.\+h}$>$}

\hyperlink{group__sending-data_gafd5fdd285a0e25ba7e3e1051deec1001}{lws\+\_\+write()} -\/ Apply protocol then write data to client 
\begin{DoxyParams}{Parameters}
{\em wsi} & Websocket instance (available from user callback) \\
\hline
{\em buf} & The data to send. For data being sent on a websocket connection (ie, not default http), this buffer M\+U\+ST have L\+W\+S\+\_\+\+P\+RE bytes valid B\+E\+F\+O\+RE the pointer. This is so the protocol header data can be added in-\/situ. \\
\hline
{\em len} & Count of the data bytes in the payload starting from buf \\
\hline
{\em protocol} & Use L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP to reply to an http connection, and one of L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY or L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT to send appropriate data on a websockets connection. Remember to allow the extra bytes before and after buf if L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY or L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT are used.\\
\hline
\end{DoxyParams}
This function provides the way to issue data back to the client for both http and websocket protocols.

I\+M\+P\+O\+R\+T\+A\+NT N\+O\+T\+I\+C\+E!

When sending with websocket protocol

L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+XT, L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+B\+I\+N\+A\+RY, L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+C\+O\+N\+T\+I\+N\+U\+A\+T\+I\+ON, L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+P\+I\+NG, L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+P\+O\+NG

the send buffer has to have L\+W\+S\+\_\+\+P\+RE bytes valid B\+E\+F\+O\+RE the buffer pointer you pass to \hyperlink{group__sending-data_gafd5fdd285a0e25ba7e3e1051deec1001}{lws\+\_\+write()}.

This allows us to add protocol info before and after the data, and send as one packet on the network without payload copying, for maximum efficiency.

So for example you need this kind of code to use lws\+\_\+write with a 128-\/byte payload

char buf\mbox{[}L\+W\+S\+\_\+\+P\+RE + 128\mbox{]};

// fill your part of the buffer... for example here it\textquotesingle{}s all zeros memset(\&buf\mbox{[}\+L\+W\+S\+\_\+\+P\+R\+E\mbox{]}, 0, 128);

lws\+\_\+write(wsi, \&buf\mbox{[}\+L\+W\+S\+\_\+\+P\+R\+E\mbox{]}, 128, L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+T\+E\+X\+T);

When sending H\+T\+TP, with

L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+TP, L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+H\+E\+A\+D\+E\+RS L\+W\+S\+\_\+\+W\+R\+I\+T\+E\+\_\+\+H\+T\+T\+P\+\_\+\+F\+I\+N\+AL

there is no protocol data prepended, and don\textquotesingle{}t need to take care about the L\+W\+S\+\_\+\+P\+RE bytes valid before the buffer pointer.

L\+W\+S\+\_\+\+P\+RE is at least the frame nonce + 2 header + 8 length L\+W\+S\+\_\+\+S\+E\+N\+D\+\_\+\+B\+U\+F\+F\+E\+R\+\_\+\+P\+O\+S\+T\+\_\+\+P\+A\+D\+D\+I\+NG is deprecated, it\textquotesingle{}s now 0 and can be left off. The example apps no longer use it.

Pad L\+W\+S\+\_\+\+P\+RE to the C\+PU word size, so that word references to the address immediately after the padding won\textquotesingle{}t cause an unaligned access error. Sometimes for performance reasons the recommended padding is even larger than sizeof(void $\ast$). \begin{DoxyVerb} In the case of sending using websocket protocol, be sure to allocate
 valid storage before and after buf as explained above.  This scheme
 allows maximum efficiency of sending data and protocol in a single
 packet while not burdening the user code with any protocol knowledge.

 Return may be -1 for a fatal error needing connection close, or a
 positive number reflecting the amount of bytes actually sent.  This
 can be less than the requested number of bytes due to OS memory
 pressure at any given time.\end{DoxyVerb}
 