mirror of
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ed4acef481
This adds a serverside implementation of RFC7233 HTTP ranges. - LWS_WITH_RANGES is on by default at cmake - Accept-Ranges: bytes is added if LWS_WITH_RANGES is enabled - Both single ranges and multipart (2+) ranges are supported Test with curl like this Single $ $ curl -s -r 64-95 http://localhost:7681/libwebsockets.org-logo.png | hexdump -C 00000000 2e 01 fd 9d 12 27 00 00 00 19 74 45 58 74 53 6f |.....'....tEXtSo| 00000010 66 74 77 61 72 65 00 77 77 77 2e 69 6e 6b 73 63 |ftware.www.inksc| Multipart $ curl -s -r 64-95,128-143 http://localhost:7681/libwebsockets.org-logo.png | hexdump -C 00000000 5f 6c 77 73 0d 0a 43 6f 6e 74 65 6e 74 2d 54 79 |_lws..Content-Ty| 00000010 70 65 3a 20 69 6d 61 67 65 2f 70 6e 67 0d 0a 43 |pe: image/png..C| 00000020 6f 6e 74 65 6e 74 2d 52 61 6e 67 65 3a 20 62 79 |ontent-Range: by| 00000030 74 65 73 20 36 34 2d 39 35 2f 37 30 32 39 0d 0a |tes 64-95/7029..| 00000040 0d 0a 2e 01 fd 9d 12 27 00 00 00 19 74 45 58 74 |.......'....tEXt| 00000050 53 6f 66 74 77 61 72 65 00 77 77 77 2e 69 6e 6b |Software.www.ink| 00000060 73 63 5f 6c 77 73 0d 0a 43 6f 6e 74 65 6e 74 2d |sc_lws..Content-| 00000070 54 79 70 65 3a 20 69 6d 61 67 65 2f 70 6e 67 0d |Type: image/png.| 00000080 0a 43 6f 6e 74 65 6e 74 2d 52 61 6e 67 65 3a 20 |.Content-Range: | 00000090 62 79 74 65 73 20 31 32 38 2d 31 34 33 2f 37 30 |bytes 128-143/70| 000000a0 32 39 0d 0a 0d 0a 05 14 50 40 05 15 a5 c4 60 43 |29......P@....`C| 000000b0 91 c4 4a d4 c4 fc 5f 6c 77 73 0d 00 |..J..._lws..| The corresponding header part is like this 0x0030: 4854 5450 2f31 2e31 2032 3036 HTTP/1.1.206 0x0040: 200d 0a73 6572 7665 723a 206c 7773 7773 ...server:.lwsws 0x0050: 0d0a 636f 6e74 656e 742d 7479 7065 3a20 ..content-type:. 0x0060: 6d75 6c74 6970 6172 742f 6279 7465 7261 multipart/bytera 0x0070: 6e67 6573 0d0a 6163 6365 7074 2d72 616e nges..accept-ran 0x0080: 6765 733a 2062 7974 6573 0d0a 636f 6e74 ges:.bytes..cont 0x0090: 656e 742d 6c65 6e67 7468 3a20 3138 380d ent-length:.188. 0x00a0: 0a63 6163 6865 2d63 6f6e 7472 6f6c 3a20 .cache-control:. 0x00b0: 7072 6976 6174 6520 6d61 782d 6167 653a private.max-age: 0x00c0: 2036 300d 0a63 6f6e 6e65 6374 696f 6e3a .60..connection: 0x00d0: 206b 6565 702d 616c 6976 650d 0a65 7461 .keep-alive..eta 0x00e0: 673a 2030 3030 3031 4237 3535 3444 3433 g:.00001B7554D43 0x00f0: 3033 330d 0a0d 0a 033....
227 lines
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227 lines
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<td id="projectlogo"><img alt="Logo" src="libwebsockets.org-logo.png"/></td>
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<td id="projectalign" style="padding-left: 0.5em;">
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<div id="projectname">libwebsockets
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</div>
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<div id="projectbrief">Lightweight C library for HTML5 websockets</div>
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<div id="doc-content">
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<div class="header">
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<div class="summary">
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<a href="#enum-members">Enumerations</a> |
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<a href="#func-members">Functions</a> </div>
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<div class="headertitle">
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<div class="title">Sending data</div> </div>
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</div><!--header-->
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<table class="memberdecls">
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="enum-members"></a>
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Enumerations</h2></td></tr>
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<tr class="memitem:ga98b099cf8c1c7e38ad78501f270e193d"><td class="memItemLeft" align="right" valign="top">enum  </td><td class="memItemRight" valign="bottom"><a class="el" href="group__sending-data.html#ga98b099cf8c1c7e38ad78501f270e193d">lws_write_protocol</a> { <br />
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  <a class="el" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db">LWS_WRITE_TEXT</a> = 0,
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<a class="el" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2">LWS_WRITE_BINARY</a> = 1,
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<a class="el" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826">LWS_WRITE_CONTINUATION</a> = 2,
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<a class="el" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e">LWS_WRITE_HTTP</a> = 3,
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<br />
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  <b>LWS_WRITE_PING</b> = 5,
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<b>LWS_WRITE_PONG</b> = 6,
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<b>LWS_WRITE_HTTP_FINAL</b> = 7,
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<a class="el" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917">LWS_WRITE_HTTP_HEADERS</a> = 8,
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  <a class="el" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3">LWS_WRITE_NO_FIN</a> = 0x40,
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<a class="el" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce">LWS_WRITE_CLIENT_IGNORE_XOR_MASK</a> = 0x80
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</table><table class="memberdecls">
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
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Functions</h2></td></tr>
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<tr class="memitem:gafd5fdd285a0e25ba7e3e1051deec1001"><td class="memItemLeft" align="right" valign="top">LWS_VISIBLE LWS_EXTERN int </td><td class="memItemRight" valign="bottom"><a class="el" href="group__sending-data.html#gafd5fdd285a0e25ba7e3e1051deec1001">lws_write</a> (struct lws *wsi, unsigned char *buf, size_t len, enum <a class="el" href="group__sending-data.html#ga98b099cf8c1c7e38ad78501f270e193d">lws_write_protocol</a> protocol)</td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
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<p>APIs related to writing data on a connection </p>
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<h2 class="groupheader">Enumeration Type Documentation</h2>
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<a id="ga98b099cf8c1c7e38ad78501f270e193d"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#ga98b099cf8c1c7e38ad78501f270e193d">§ </a></span>lws_write_protocol</h2>
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<tr>
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<td class="memname">enum <a class="el" href="group__sending-data.html#ga98b099cf8c1c7e38ad78501f270e193d">lws_write_protocol</a></td>
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</table>
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</div><div class="memdoc">
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<p><code>#include <<a class="el" href="libwebsockets_8h.html">lib/libwebsockets.h</a>></code></p>
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<table class="fieldtable">
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<tr><th colspan="2">Enumerator</th></tr><tr><td class="fieldname"><a id="gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db"></a>LWS_WRITE_TEXT </td><td class="fielddoc"><p>Send a ws TEXT message,the pointer must have LWS_PRE valid memory behind it. The receiver expects only valid utf-8 in the payload </p>
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</td></tr>
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<tr><td class="fieldname"><a id="gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2"></a>LWS_WRITE_BINARY </td><td class="fielddoc"><p>Send a ws BINARY message, the pointer must have LWS_PRE valid memory behind it. Any sequence of bytes is valid </p>
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</td></tr>
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<tr><td class="fieldname"><a id="gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826"></a>LWS_WRITE_CONTINUATION </td><td class="fielddoc"><p>Continue a previous ws message, the pointer must have LWS_PRE valid memory behind it </p>
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</td></tr>
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<tr><td class="fieldname"><a id="gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e"></a>LWS_WRITE_HTTP </td><td class="fielddoc"><p>Send HTTP content </p>
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</td></tr>
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<tr><td class="fieldname"><a id="gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917"></a>LWS_WRITE_HTTP_HEADERS </td><td class="fielddoc"><p>Send http headers (http2 encodes this payload and LWS_WRITE_HTTP 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) </p>
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</td></tr>
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<tr><td class="fieldname"><a id="gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3"></a>LWS_WRITE_NO_FIN </td><td class="fielddoc"><p>This part of the message is not the end of the message </p>
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</td></tr>
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<tr><td class="fieldname"><a id="gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce"></a>LWS_WRITE_CLIENT_IGNORE_XOR_MASK </td><td class="fielddoc"><p>client packet payload goes out on wire unmunged only useful for security tests since normal servers cannot decode the content if used </p>
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</td></tr>
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</table>
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<div class="fragment"><div class="line"><a name="l03191"></a><span class="lineno"> 3191</span>  {</div><div class="line"><a name="l03192"></a><span class="lineno"> 3192</span>  <a class="code" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db">LWS_WRITE_TEXT</a> = 0,</div><div class="line"><a name="l03196"></a><span class="lineno"> 3196</span>  <a class="code" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2">LWS_WRITE_BINARY</a> = 1,</div><div class="line"><a name="l03199"></a><span class="lineno"> 3199</span>  <a class="code" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826">LWS_WRITE_CONTINUATION</a> = 2,</div><div class="line"><a name="l03202"></a><span class="lineno"> 3202</span>  <a class="code" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e">LWS_WRITE_HTTP</a> = 3,</div><div class="line"><a name="l03205"></a><span class="lineno"> 3205</span>  <span class="comment">/* LWS_WRITE_CLOSE is handled by lws_close_reason() */</span></div><div class="line"><a name="l03206"></a><span class="lineno"> 3206</span>  LWS_WRITE_PING = 5,</div><div class="line"><a name="l03207"></a><span class="lineno"> 3207</span>  LWS_WRITE_PONG = 6,</div><div class="line"><a name="l03208"></a><span class="lineno"> 3208</span> </div><div class="line"><a name="l03209"></a><span class="lineno"> 3209</span>  <span class="comment">/* Same as write_http but we know this write ends the transaction */</span></div><div class="line"><a name="l03210"></a><span class="lineno"> 3210</span>  LWS_WRITE_HTTP_FINAL = 7,</div><div class="line"><a name="l03211"></a><span class="lineno"> 3211</span> </div><div class="line"><a name="l03212"></a><span class="lineno"> 3212</span>  <span class="comment">/* HTTP2 */</span></div><div class="line"><a name="l03213"></a><span class="lineno"> 3213</span> </div><div class="line"><a name="l03214"></a><span class="lineno"> 3214</span>  <a class="code" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917">LWS_WRITE_HTTP_HEADERS</a> = 8,</div><div class="line"><a name="l03221"></a><span class="lineno"> 3221</span>  <span class="comment">/****** add new things just above ---^ ******/</span></div><div class="line"><a name="l03222"></a><span class="lineno"> 3222</span> </div><div class="line"><a name="l03223"></a><span class="lineno"> 3223</span>  <span class="comment">/* flags */</span></div><div class="line"><a name="l03224"></a><span class="lineno"> 3224</span> </div><div class="line"><a name="l03225"></a><span class="lineno"> 3225</span>  <a class="code" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3">LWS_WRITE_NO_FIN</a> = 0x40,</div><div class="line"><a name="l03228"></a><span class="lineno"> 3228</span>  <a class="code" href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce">LWS_WRITE_CLIENT_IGNORE_XOR_MASK</a> = 0x80</div><div class="line"><a name="l03232"></a><span class="lineno"> 3232</span> };</div><div class="ttc" id="group__sending-data_html_gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e"><div class="ttname"><a href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193dabb6705e1d1327cdda5025be28f07712e">LWS_WRITE_HTTP</a></div><div class="ttdef"><b>Definition:</b> libwebsockets.h:3202</div></div>
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<div class="ttc" id="group__sending-data_html_gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3"><div class="ttname"><a href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da115440f272a5d55518adfc8099acfee3">LWS_WRITE_NO_FIN</a></div><div class="ttdef"><b>Definition:</b> libwebsockets.h:3225</div></div>
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<div class="ttc" id="group__sending-data_html_gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db"><div class="ttname"><a href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da80e8f169fda236c56bfb795ed62903db">LWS_WRITE_TEXT</a></div><div class="ttdef"><b>Definition:</b> libwebsockets.h:3192</div></div>
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<div class="ttc" id="group__sending-data_html_gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2"><div class="ttname"><a href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193daf6486c0dba50c44198100717721d9ab2">LWS_WRITE_BINARY</a></div><div class="ttdef"><b>Definition:</b> libwebsockets.h:3196</div></div>
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<div class="ttc" id="group__sending-data_html_gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce"><div class="ttname"><a href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da220d8e8652d9b97fb66e476e2a60ffce">LWS_WRITE_CLIENT_IGNORE_XOR_MASK</a></div><div class="ttdef"><b>Definition:</b> libwebsockets.h:3228</div></div>
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<div class="ttc" id="group__sending-data_html_gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826"><div class="ttname"><a href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193da10047eb05b5e1c298151dc47a5b44826">LWS_WRITE_CONTINUATION</a></div><div class="ttdef"><b>Definition:</b> libwebsockets.h:3199</div></div>
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<div class="ttc" id="group__sending-data_html_gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917"><div class="ttname"><a href="group__sending-data.html#gga98b099cf8c1c7e38ad78501f270e193dafe5a38e940ce56708ac814627e9c0917">LWS_WRITE_HTTP_HEADERS</a></div><div class="ttdef"><b>Definition:</b> libwebsockets.h:3214</div></div>
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<h2 class="groupheader">Function Documentation</h2>
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<a id="gafd5fdd285a0e25ba7e3e1051deec1001"></a>
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<h2 class="memtitle"><span class="permalink"><a href="#gafd5fdd285a0e25ba7e3e1051deec1001">§ </a></span>lws_write()</h2>
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<td class="memname">LWS_VISIBLE LWS_EXTERN int lws_write </td>
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<td>(</td>
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<td class="paramtype">struct lws * </td>
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<td class="paramname"><em>wsi</em>, </td>
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<td class="paramkey"></td>
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<td class="paramtype">unsigned char * </td>
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<td class="paramname"><em>buf</em>, </td>
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<td class="paramtype">size_t </td>
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<td class="paramname"><em>len</em>, </td>
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<td class="paramtype">enum <a class="el" href="group__sending-data.html#ga98b099cf8c1c7e38ad78501f270e193d">lws_write_protocol</a> </td>
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<td class="paramname"><em>protocol</em> </td>
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<td>)</td>
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<p><code>#include <<a class="el" href="libwebsockets_8h.html">lib/libwebsockets.h</a>></code></p>
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<p><a class="el" href="group__sending-data.html#gafd5fdd285a0e25ba7e3e1051deec1001">lws_write()</a> - Apply protocol then write data to client </p><dl class="params"><dt>Parameters</dt><dd>
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<table class="params">
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<tr><td class="paramname">wsi</td><td>Websocket instance (available from user callback) </td></tr>
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<tr><td class="paramname">buf</td><td>The data to send. For data being sent on a websocket connection (ie, not default http), this buffer MUST have LWS_PRE bytes valid BEFORE the pointer. This is so the protocol header data can be added in-situ. </td></tr>
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<tr><td class="paramname">len</td><td>Count of the data bytes in the payload starting from buf </td></tr>
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<tr><td class="paramname">protocol</td><td>Use LWS_WRITE_HTTP to reply to an http connection, and one of LWS_WRITE_BINARY or LWS_WRITE_TEXT to send appropriate data on a websockets connection. Remember to allow the extra bytes before and after buf if LWS_WRITE_BINARY or LWS_WRITE_TEXT are used.</td></tr>
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</table>
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</dd>
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</dl>
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<p>This function provides the way to issue data back to the client for both http and websocket protocols.</p>
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<p>IMPORTANT NOTICE!</p>
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<p>When sending with websocket protocol</p>
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<p>LWS_WRITE_TEXT, LWS_WRITE_BINARY, LWS_WRITE_CONTINUATION, LWS_WRITE_PING, LWS_WRITE_PONG</p>
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<p>the send buffer has to have LWS_PRE bytes valid BEFORE the buffer pointer you pass to <a class="el" href="group__sending-data.html#gafd5fdd285a0e25ba7e3e1051deec1001">lws_write()</a>.</p>
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<p>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.</p>
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<p>So for example you need this kind of code to use lws_write with a 128-byte payload</p>
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<p>char buf[LWS_PRE + 128];</p>
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<p>// fill your part of the buffer... for example here it's all zeros memset(&buf[LWS_PRE], 0, 128);</p>
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<p>lws_write(wsi, &buf[LWS_PRE], 128, LWS_WRITE_TEXT);</p>
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<p>When sending HTTP, with</p>
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<p>LWS_WRITE_HTTP, LWS_WRITE_HTTP_HEADERS LWS_WRITE_HTTP_FINAL</p>
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<p>there is no protocol data prepended, and don't need to take care about the LWS_PRE bytes valid before the buffer pointer.</p>
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<p>LWS_PRE is at least the frame nonce + 2 header + 8 length LWS_SEND_BUFFER_POST_PADDING is deprecated, it's now 0 and can be left off. The example apps no longer use it.</p>
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<p>Pad LWS_PRE to the CPU word size, so that word references to the address immediately after the padding won't cause an unaligned access error. Sometimes for performance reasons the recommended padding is even larger than sizeof(void *). </p><pre class="fragment"> In the case of sending using websocket protocol, be sure to allocate
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valid storage before and after buf as explained above. This scheme
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allows maximum efficiency of sending data and protocol in a single
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packet while not burdening the user code with any protocol knowledge.
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Return may be -1 for a fatal error needing connection close, or the
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number of bytes sent.
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</pre><h1>Truncated Writes </h1>
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<p>The OS may not accept everything you asked to write on the connection.</p>
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<p>Posix defines POLLOUT indication from poll() to show that the connection will accept more write data, but it doesn't specifiy how much. It may just accept one byte of whatever you wanted to send.</p>
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<p>LWS will buffer the remainder automatically, and send it out autonomously.</p>
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<p>During that time, WRITABLE callbacks will be suppressed.</p>
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<p>This is to handle corner cases where unexpectedly the OS refuses what we usually expect it to accept. You should try to send in chunks that are almost always accepted in order to avoid the inefficiency of the buffering. </p>
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