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<div id="projectname">libnl <span id="projectnumber">1.1</span></div>
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<a href="#nested-classes">Data Structures</a> |
<a href="#define-members">Defines</a> |
<a href="#enum-members">Enumerations</a> </div>
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<h1>Cache Implementation</h1> </div>
<div class="ingroups"><a class="el" href="group__cache.html">Cache</a></div></div>
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<tr><td colspan="2"><h2><a name="nested-classes"></a>
Data Structures</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">struct  </td><td class="memItemRight" valign="bottom"><a class="el" href="structnl__msgtype.html">nl_msgtype</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Message type to cache action association. <a href="structnl__msgtype.html#_details">More...</a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">struct  </td><td class="memItemRight" valign="bottom"><a class="el" href="structnl__af__group.html">nl_af_group</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Address family to netlink group association. <a href="structnl__af__group.html#_details">More...</a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">struct  </td><td class="memItemRight" valign="bottom"><a class="el" href="structnl__parser__param.html">nl_parser_param</a></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">struct  </td><td class="memItemRight" valign="bottom"><a class="el" href="structnl__cache__ops.html">nl_cache_ops</a></td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Cache Operations. <a href="structnl__cache__ops.html#_details">More...</a><br/></td></tr>
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Defines</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="ga66849a5e1c9a8183d541449b8b758155"></a><!-- doxytag: member="cache_api::NL_ACT_MAX" ref="ga66849a5e1c9a8183d541449b8b758155" args="" -->
#define </td><td class="memItemRight" valign="bottom"><b>NL_ACT_MAX</b>   (__NL_ACT_MAX - 1)</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="gacaf5bba6424e223ad9e0e9ea23451303"></a><!-- doxytag: member="cache_api::END_OF_MSGTYPES_LIST" ref="gacaf5bba6424e223ad9e0e9ea23451303" args="" -->
#define </td><td class="memItemRight" valign="bottom"><b>END_OF_MSGTYPES_LIST</b>   { -1, -1, NULL }</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="gaae512508ffeb48dcf4b71867d07277f9"></a><!-- doxytag: member="cache_api::END_OF_GROUP_LIST" ref="gaae512508ffeb48dcf4b71867d07277f9" args="" -->
#define </td><td class="memItemRight" valign="bottom"><b>END_OF_GROUP_LIST</b>   AF_UNSPEC, 0</td></tr>
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Enumerations</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">enum  </td><td class="memItemRight" valign="bottom">{ <br/>
  <b>NL_ACT_UNSPEC</b>,
<b>NL_ACT_NEW</b>,
<b>NL_ACT_DEL</b>,
<b>NL_ACT_GET</b>,
<br/>
  <b>NL_ACT_SET</b>,
<b>NL_ACT_CHANGE</b>,
<b>__NL_ACT_MAX</b>
<br/>
}</td></tr>
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<hr/><a name="_details"></a><h2>Detailed Description</h2>
<dl class="user"><dt><b>1) Cache Definition</b></dt><dd><div class="fragment"><pre class="fragment"> <span class="keyword">struct </span><a class="code" href="structnl__cache__ops.html" title="Cache Operations.">nl_cache_ops</a> my_cache_ops = {
.co_name = <span class="stringliteral">"route/link"</span>,
.co_protocol = NETLINK_ROUTE,
.co_hdrsize = <span class="keyword">sizeof</span>(<span class="keyword">struct </span>ifinfomsg),
.co_obj_ops = &my_obj_ops,
};
</pre></div></dd></dl>
<dl class="user"><dt><b>2) </b></dt><dd><div class="fragment"><pre class="fragment"> <span class="comment">// The simplest way to fill a cache is by providing a request-update</span>
<span class="comment">// function which must trigger a complete dump on the kernel-side of</span>
<span class="comment">// whatever the cache covers.</span>
<span class="keyword">static</span> <span class="keywordtype">int</span> my_request_update(<span class="keyword">struct</span> nl_cache *cache,
<span class="keyword">struct</span> nl_handle *socket)
{
<span class="comment">// In this example, we request a full dump of the interface table</span>
<span class="keywordflow">return</span> <a class="code" href="group__rtnl.html#ga1fcd1a88d7f810c50849f13d97b5fe10" title="Send routing netlink request message.">nl_rtgen_request</a>(socket, RTM_GETLINK, AF_UNSPEC, <a class="code" href="group__msg.html#ga8d4fb2458c013decb6673f41c52c07b1" title="Dump all entries.">NLM_F_DUMP</a>);
}
<span class="comment">// The resulting netlink messages sent back will be fed into a message</span>
<span class="comment">// parser one at a time. The message parser has to extract all relevant</span>
<span class="comment">// information from the message and create an object reflecting the</span>
<span class="comment">// contents of the message and pass it on to the parser callback function</span>
<span class="comment">// provide which will add the object to the cache.</span>
<span class="keyword">static</span> <span class="keywordtype">int</span> my_msg_parser(<span class="keyword">struct</span> <a class="code" href="structnl__cache__ops.html" title="Cache Operations.">nl_cache_ops</a> *ops, <span class="keyword">struct</span> <a class="code" href="structsockaddr__nl.html" title="Netlink socket address.">sockaddr_nl</a> *who,
<span class="keyword">struct</span> <a class="code" href="structnlmsghdr.html" title="Netlink message header.">nlmsghdr</a> *nlh, <span class="keyword">struct</span> <a class="code" href="structnl__parser__param.html">nl_parser_param</a> *pp)
{
<span class="keyword">struct </span>my_obj *obj;
obj = my_obj_alloc();
obj->ce_msgtype = nlh-><a class="code" href="structnlmsghdr.html#a7232c4e6cb513010e64887b7eebf8823" title="Message type (content type)">nlmsg_type</a>;
<span class="comment">// Parse the netlink message and continue creating the object.</span>
err = pp->pp_cb((<span class="keyword">struct</span> nl_object *) obj, pp);
<span class="keywordflow">if</span> (err < 0)
<span class="keywordflow">goto</span> errout;
}
<span class="keyword">struct </span><a class="code" href="structnl__cache__ops.html" title="Cache Operations.">nl_cache_ops</a> my_cache_ops = {
...
.<a class="code" href="structnl__cache__ops.html#a93ec4756f5c0ae7c105cf3b3b1473476" title="Called whenever an update of the cache is required.">co_request_update</a> = my_request_update,
.co_msg_parser = my_msg_parser,
};
</pre></div></dd></dl>
<dl class="user"><dt><b>3) Notification based Updates</b></dt><dd><div class="fragment"><pre class="fragment"> <span class="comment">// Caches can be kept up-to-date based on notifications if the kernel</span>
<span class="comment">// sends out notifications whenever an object is added/removed/changed.</span>
<span class="comment">//</span>
<span class="comment">// It is trivial to support this, first a list of groups needs to be</span>
<span class="comment">// defined which are required to join in order to receive all necessary</span>
<span class="comment">// notifications. The groups are separated by address family to support</span>
<span class="comment">// the common situation where a separate group is used for each address</span>
<span class="comment">// family. If there is only one group, simply specify AF_UNSPEC.</span>
<span class="keyword">static</span> <span class="keyword">struct </span><a class="code" href="structnl__af__group.html" title="Address family to netlink group association.">nl_af_group</a> addr_groups[] = {
{ AF_INET, RTNLGRP_IPV4_IFADDR },
{ AF_INET6, RTNLGRP_IPV6_IFADDR },
{ END_OF_GROUP_LIST },
};
<span class="comment">// In order for the caching system to know the meaning of each message</span>
<span class="comment">// type it requires a table which maps each supported message type to</span>
<span class="comment">// a cache action, e.g. RTM_NEWADDR means address has been added or</span>
<span class="comment">// updated, RTM_DELADDR means address has been removed.</span>
<span class="keyword">static</span> <span class="keyword">struct </span><a class="code" href="structnl__cache__ops.html" title="Cache Operations.">nl_cache_ops</a> rtnl_addr_ops = {
...
.co_msgtypes = {
{ RTM_NEWADDR, NL_ACT_NEW, <span class="stringliteral">"new"</span> },
{ RTM_DELADDR, NL_ACT_DEL, <span class="stringliteral">"del"</span> },
{ RTM_GETADDR, NL_ACT_GET, <span class="stringliteral">"get"</span> },
END_OF_MSGTYPES_LIST,
},
.co_groups = addr_groups,
};
<span class="comment">// It is now possible to keep the cache up-to-date using the cache manager.</span>
</pre></div> </dd></dl>
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Fedora
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14
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x86_64
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media
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updates
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by-pkgid
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87b89b73c41f4440bb86afd421c7548f
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files
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120
