{"id":199,"date":"2014-02-11T17:24:58","date_gmt":"2014-02-11T09:24:58","guid":{"rendered":"http:\/\/cmesoft.com\/?p=199"},"modified":"2014-02-11T17:55:35","modified_gmt":"2014-02-11T09:55:35","slug":"netlink-socket-%e7%bc%96%e7%a8%8b%e4%b9%8bwhy-how","status":"publish","type":"post","link":"http:\/\/cmesoft.com\/?p=199","title":{"rendered":"netlink socket \u7f16\u7a0b\u4e4bwhy & how"},"content":{"rendered":"


\n\u539f\u4f5c\u8005: Kevin Kaichuan He@2005-1-5
\n\u7ffb\u8bd1\u6574\u7406:duanjigang @2008-9-15
\n\u539f\u6587: http:\/\/www.linuxjournal.com\/article\/7356
\n\u672c\u6587\u6700\u65e9\u53d1\u5e03\u4e8echinaunix\u7684\u5185\u6838\u677f\u5757\uff0c\u5730\u5740\u4e3a:http:\/\/bbs.chinaunix.net\/thread-1274437-1-1.html
\n<\/strong>
\n\u5f00\u53d1\u548c\u7ef4\u62a4\u5185\u6838\u662f\u4e00\u4ef6\u5f88\u7e41\u6742\u7684\u5de5\u4f5c\uff0c\u56e0\u6b64\uff0c\u53ea\u6709\u90a3\u4e9b\u6700\u91cd\u8981\u6216\u8005\u4e0e\u7cfb\u7edf\u6027\u80fd\u606f\u606f\u76f8\u5173\u7684\u4ee3\u7801\u624d\u5c06\u5176\u5b89\u6392\u5728\u5185\u6838\u4e2d\u3002\u5176\u5b83\u7a0b\u5e8f\uff0c\u6bd4\u5982GUI\uff0c\u7ba1\u7406\u4ee5\u53ca\u63a7\u5236\u90e8\u5206\u7684\u4ee3\u7801\uff0c\u4e00\u822c\u90fd\u4f1a\u4f5c\u4e3a\u7528\u6237\u6001\u7a0b\u5e8f\u3002\u5728linux\u7cfb\u7edf\u4e2d\uff0c\u628a\u7cfb\u7edf\u7684\u67d0\u4e2a\u7279\u6027\u5206\u5272\u6210\u5728\u5185\u6838\u4e2d\u548c\u5728\u7528\u6237\u7a7a\u95f4\u4e2d\u5206\u522b\u5b9e\u73b0\u4e00\u90e8\u5206\u7684\u505a\u6cd5\u662f\u5f88\u5e38\u89c1\u7684(\u6bd4\u5982linux\u7cfb\u7edf\u7684\u9632\u706b\u5899\u5c31\u5206\u6210\u4e86\u5185\u6838\u6001\u7684Netfilter\u548c\u7528\u6237\u6001\u7684iptables)\u3002\u7136\u800c\uff0c\u5185\u6838\u7a0b\u5e8f\u4e0e\u7528\u6237\u6001\u7684\u7a0b\u5e8f\u53c8\u662f\u600e\u6837\u884c\u901a\u8baf\u7684\u5462\uff1f
\n\u7b54\u6848\u5c31\u662f\u901a\u8fc7\u5404\u79cd\u5404\u6837\u7684\u7528\u6237\u6001\u548c\u5185\u6838\u6001\u7684IPC(interprocess communication )\u673a\u5236\u6765\u5b9e\u73b0\u3002\u6bd4\u5982\u7cfb\u7edf\u8c03\u7528\uff0cioctl\u63a5\u53e3\uff0cproc\u6587\u4ef6\u7cfb\u7edf\u4ee5\u53canetlink <\/p>\n

socket,\u672c\u6587\u5c31\u662f\u8981\u8ba8\u8bbanetlink socekt\u5e76\u5411\u8bfb\u8005\u5c55\u793a\u8fd9\u79cd\u7528\u7f51\u7edc
\n\u901a\u8baf\u63a5\u53e3\u65b9\u5f0f\u5b9e\u73b0\u7684IPC\u673a\u5236\u7684\u4f18\u70b9\u3002<\/p>\n

\u4ecb\u7ecd<\/strong><\/h2>\n

netlink socekt\u662f\u4e00\u79cd\u7528\u4e8e\u5728\u5185\u6838\u6001\u548c\u7528\u6237\u6001\u8fdb\u7a0b\u4e4b\u95f4\u8fdb\u884c\u6570\u636e\u4f20\u8f93\u7684\u7279\u6b8a\u7684IPC\u3002\u5b83\u901a\u8fc7\u4e3a\u5185\u6838\u6a21\u5757\u63d0
\n\u4f9b\u4e00\u7ec4\u7279\u6b8a\u7684API\uff0c\u5e76\u4e3a\u7528\u6237\u7a0b\u5e8f\u63d0\u4f9b\u4e86\u4e00\u7ec4\u6807\u51c6\u7684socket \u63a5\u53e3\u7684\u65b9\u5f0f\uff0c\u5b9e\u73b0\u4e86\u4e00\u79cd\u5168\u53cc\u5de5\u7684\u901a\u8baf\u8fde\u63a5\u3002\u7c7b\u4f3c\u4e8eTCP\/IP\u4e2d\u4f7f\u7528AF_INET\u5730\u5740\u65cf\u4e00\u6837\uff0cnetlink <\/p>\n

socket\u4f7f\u7528\u5730\u5740\u65cfAF_NETLINK\u3002\u6bcf\u4e00\u4e2anetlink
\nsocket\u5728\u5185\u6838\u5934\u6587\u4ef6
\n
\ninclude\/linux\/netlink.h
\n<\/coolcode><\/p>\n

\u4e2d\u5b9a\u4e49\u81ea\u5df1\u7684\u534f\u8bae\u7c7b\u578b\u3002
\n\u4e0b\u9762\u662fnetlink socket \u76ee\u524d\u7684\u7279\u6027\u96c6\u5408\u4ee5\u53ca\u5b83\u652f\u6301\u7684\u534f\u8bae\u7c7b\u578b\uff1a
\n
\nNETLINK_ROUTE \u7528\u6237\u7a7a\u95f4\u7684\u8def\u7531\u5b88\u62a4\u7a0b\u5e8f\u4e4b\u95f4\u7684\u901a\u8baf\u901a\u9053\uff0c\u6bd4\u5982BGP,OSPF,RIP\u4ee5\u53ca\u5185\u6838\u6570\u636e\u8f6c\u53d1\u6a21\u5757\u3002\u7528\u6237\u6001\u7684\u8def\u7531\u5b88\u62a4\u7a0b\u5e8f\u901a\u8fc7\u6b64\u7c7b\u578b\u7684\u534f\u8bae\u6765\u66f4\u65b0\u5185\u6838\u4e2d\u7684<\/p>\n

\u8def\u7531\u8868\u3002
\nNETLINK_FIREWALL:\u63a5\u6536IPV4\u9632\u706b\u5899\u4ee3\u7801\u53d1\u9001\u7684\u6570\u636e\u5305\u3002
\nNETLINK_NFLOG:\u7528\u6237\u6001\u7684iptables\u7ba1\u7406\u5de5\u5177\u548c\u5185\u6838\u4e2d\u7684netfilter\u6a21\u5757\u4e4b\u95f4\u901a\u8baf\u7684\u901a\u9053\u3002
\nNETLINK_ARPD:\u7528\u6765\u4ece\u7528\u6237\u7a7a\u95f4\u7ba1\u7406\u5185\u6838\u4e2d\u7684ARP\u8868\u3002
\n<\/coolcode><\/p>\n

\u4e3a\u4ec0\u4e48\u4ee5\u4e0a\u7684\u529f\u80fd\u5728\u5b9e\u73b0\u7528\u6237\u7a0b\u5e8f\u548c\u5185\u6838\u7a0b\u5e8f\u901a\u8baf\u65f6\uff0c\u90fd\u4f7f\u7528netlink\u65b9\u6cd5\u800c\u4e0d\u662f\u7cfb\u7edf\u8c03\u7528\uff0cioctls
\n\u6216\u8005proc\u6587\u4ef6\u7cfb\u7edf\u5462\uff1f\u539f\u56e0\u5728\u4e8e\uff1a\u4e3a\u65b0\u7684\u7279\u6027\u6dfb\u52a0\u4e00\u4e2a\u65b0\u7684\u7cfb\u7edf\u8c03\u7528,ioctls\u6216\u8005\u4e00\u4e2aproc\u6587\u4ef6\u7684\u505a\u6cd5\u5e76\u4e0d\u662f\u5f88\u5bb9\u6613\u7684\u4e00\u4ef6\u4e8b\u60c5\uff0c\u56e0\u4e3a\u6211\u4eec\u8981\u5192\u7740\u6c61\u67d3\u5185\u6838\u4ee3\u7801<\/p>\n

\u5e76\u4e14\u53ef\u80fd\u7834\u574f\u7cfb\u7edf\u7a33\u5b9a\u6027\u7684\u98ce\u9669\u53bb\u5b8c\u6210\u8fd9\u4ef6\u4e8b\u60c5\u3002
\n\u7136\u800c\uff0cnetlink socket\u5374\u662f\u5982\u6b64\u7684\u7b80\u5355\uff0c\u4f60\u53ea\u9700\u8981\u5728\u6587\u4ef6netlink.h\u4e2d\u6dfb\u52a0\u4e00\u4e2a\u5e38\u91cf\u6765\u6807\u8bc6\u4f60\u7684\u534f\u8bae\u7c7b\u578b\uff0c\u7136\u540e\uff0c\u5185\u6838\u6a21\u5757\u548c\u7528\u6237\u7a0b\u5e8f\u5c31\u53ef\u4ee5\u7acb\u523b\u4f7f\u7528socket\u98ce<\/p>\n

\u683c\u7684API\u8fdb\u884c\u901a\u8baf\u4e86\uff01
\n Netlink\u63d0\u4f9b\u4e86\u4e00\u79cd\u5f02\u6b65\u901a\u8baf\u65b9\u5f0f\uff0c\u4e0e\u5176\u4ed6socket API\u4e00\u6837\uff0c\u5b83\u63d0\u4f9b\u4e86\u4e00\u4e2asocket\u961f\u5217\u6765\u7f13\u51b2\u6216\u8005\u5e73\u6ed1
\n\u77ac\u65f6\u7684\u6d88\u606f\u9ad8\u5cf0\u3002\u53d1\u9001netlink\u6d88\u606f\u7684\u7cfb\u7edf\u8c03\u7528\u5728\u628a\u6d88\u606f\u52a0\u5165\u5230\u63a5\u6536\u8005\u7684\u6d88\u606f\u5bf9\u5217\u540e\uff0c\u4f1a\u89e6\u53d1\u63a5\u6536\u8005\u7684\u63a5\u6536\u5904\u7406\u51fd\u6570\u3002\u63a5\u6536\u8005\u5728\u63a5\u6536\u5904\u7406\u51fd\u6570\u4e0a\u4e0b\u6587\u4e2d\uff0c\u53ef\u4ee5\u51b3\u5b9a<\/p>\n

\u7acb\u5373\u5904\u7406\u6d88\u606f\u8fd8\u662f\u628a\u6d88\u606f\u653e\u5728\u961f\u5217\u4e2d\uff0c\u5728\u4ee5\u540e\u5176\u5b83\u4e0a\u4e0b\u6587\u53bb\u5904\u7406\u5b83(\u56e0\u4e3a\u6211\u4eec\u5e0c\u671b\u63a5\u6536\u5904\u7406\u51fd\u6570\u6267\u884c\u7684\u5c3d\u53ef\u80fd\u5feb)\u3002\u7cfb\u7edf\u8c03\u7528\u4e0enetlink\u4e0d\u540c\uff0c\u5b83\u9700\u8981\u4e00\u4e2a\u540c\u6b65\u7684<\/p>\n

\u5904\u7406\uff0c\u56e0\u6b64\uff0c\u5f53\u6211\u4eec\u4f7f\u7528\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\u6765\u4ece\u7528\u6237\u6001\u4f20\u9012\u6d88\u606f\u5230\u5185\u6838\u65f6\uff0c\u5982\u679c\u5904\u7406\u8fd9\u4e2a\u6d88\u606f\u7684\u65f6\u95f4\u5f88\u957f\u7684\u8bdd\uff0c\u5185\u6838\u8c03\u5ea6\u7684\u7c92\u5ea6\u5c31\u4f1a\u53d7\u5230\u5f71\u54cd\u3002
\n \u5185\u6838\u4e2d\u5b9e\u73b0\u7cfb\u7edf\u8c03\u7528\u7684\u4ee3\u7801\u90fd\u662f\u5728\u7f16\u8bd1\u65f6\u9759\u6001\u94fe\u63a5\u5230\u5185\u6838\u7684\uff0c\u56e0\u6b64\uff0c\u5728\u52a8\u6001\u52a0\u8f7d\u6a21\u5757\u4e2d\u53bb\u5305\u542b\u4e00\u4e2a\u7cfb\u7edf\u8c03\u7528\u7684\u505a\u6cd5\u662f\u4e0d\u5408\u9002\u7684\uff0c\u90a3\u662f\u5927\u591a\u6570\u8bbe\u5907\u9a71\u52a8\u7684<\/p>\n

\u505a\u6cd5\u3002\u4f7f\u7528netlink socket\u65f6,\u52a8\u6001\u52a0\u8f7d\u6a21\u5757\u4e2d\u7684netlink\u7a0b\u5e8f\u4e0d\u4f1a\u548clinux\u5185\u6838\u4e2d\u7684netlink\u90e8\u5206\u4ea7\u751f\u4efb\u4f55\u7f16\u8bd1\u65f6\u4f9d\u8d56\u5173\u7cfb\u3002
\nNetlink\u4f18\u4e8e\u7cfb\u7edf\u8c03\u7528\uff0cioctls\u548cproc\u6587\u4ef6\u7cfb\u7edf\u7684\u53e6\u5916\u4e00\u4e2a\u7279\u70b9\u5c31\u662f\u5b83\u652f\u6301\u591a\u70b9\u4f20\u9001\u3002\u4e00\u4e2a\u8fdb\u7a0b\u53ef\u4ee5\u628a\u6d88\u606f\u4f20\u8f93\u7ed9\u4e00\u4e2anetlink\u7ec4\u5730\u5740\uff0c\u7136\u540e\u4efb\u610f\u591a\u4e2a\u8fdb\u7a0b\u90fd\u53ef\u4ee5<\/p>\n

\u76d1\u542c\u90a3\u4e2a\u7ec4\u5730\u5740(\u5e76\u4e14\u63a5\u6536\u6d88\u606f)\u3002\u8fd9\u79cd\u673a\u5236\u4e3a\u5185\u6838\u5230\u7528\u6237\u6001\u7684\u4e8b\u4ef6\u5206\u53d1\u63d0\u4f9b\u4e86\u4e00\u79cd\u8fd1\u4e4e\u5b8c\u7f8e\u7684\u89e3\u51b3\u65b9\u6848\u3002
\n\u7cfb\u7edf\u8c03\u7528\u548cioctl\u90fd\u5c5e\u4e8e\u5355\u5de5\u65b9\u5f0f\u7684IPC\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u8fd9\u79cdIPC\u4f1a\u8bdd\u7684\u53d1\u8d77\u8005\u53ea\u80fd\u662f\u7528\u6237\u6001\u7a0b\u5e8f\u3002\u4f46\u662f\uff0c\u5982\u679c\u5185\u6838\u6709\u4e00\u4e2a\u7d27\u6025\u7684\u6d88\u606f\u60f3\u8981\u901a\u77e5\u7ed9\u7528\u6237\u6001\u7a0b\u5e8f\u65f6\uff0c\u8be5<\/p>\n

\u600e\u4e48\u529e\u5462\uff1f\u5982\u679c\u76f4\u63a5\u4f7f\u7528\u8fd9\u4e9bIPC\u7684\u8bdd\uff0c\u662f\u6ca1\u529e\u6cd5\u505a\u5230\u8fd9\u70b9\u7684\u3002\u901a\u5e38\u60c5\u51b5\u4e0b\uff0c\u5e94\u7528\u7a0b\u5e8f\u4f1a\u5468\u671f\u6027\u7684\u8f6e\u8be2\u5185\u6838\u4ee5\u83b7\u53d6\u72b6\u6001\u7684\u6539\u53d8\uff0c\u7136\u800c\uff0c\u9ad8\u9891\u5ea6\u7684\u8f6e\u8be2\u52bf\u5fc5\u4f1a\u589e\u52a0\u7cfb<\/p>\n

\u7edf\u7684\u8d1f\u8f7d\u3002Netlink \u901a\u8fc7\u5141\u8bb8\u5185\u6838\u521d\u59cb\u5316\u4f1a\u8bdd\u7684\u65b9\u5f0f\u5b8c\u7f8e\u7684\u89e3\u51b3\u4e86\u6b64\u95ee\u9898\uff0c\u6211\u4eec\u79f0\u4e4b\u4e3anetlink socket\u7684\u53cc\u5de5\u7279\u6027\u3002
\n \u6700\u540e\uff0cnetlink socket\u63d0\u4f9b\u4e86\u4e00\u7ec4\u5f00\u53d1\u8005\u719f\u6089\u7684BSD\u98ce\u683c\u7684API\u51fd\u6570\uff0c\u56e0\u6b64\uff0c\u76f8\u5bf9\u4e8e\u4f7f\u7528\u795e\u79d8\u7684\u7cfb\u7edf\u8c03\u7528API\u6216\u8005ioctl\u800c\u8a00\uff0cnetlink\u5f00\u53d1\u57f9\u8bad\u7684\u8d39\u7528\u4f1a<\/p>\n

\u66f4\u4f4e\u4e9b\u3002
\n \u4e0eBSD\u7684Routing socket\u7684\u5173\u7cfb
\n\u5728BSD TCP\/IP\u7684\u534f\u8bae\u6808\u5b9e\u73b0\u4e2d\uff0c\u6709\u4e00\u79cd\u7279\u6b8a\u7684socket\u53eb\u505aRouting socket.\u5b83\u7684\u5730\u5740\u65cf\u4e3aAF_ROUTE, \u534f\u8bae\u65cf\u4e3aPF_ROUTE, socket\u7c7b\u578b\u4e3aSOCK_RAW. \u8fd9\u79cd<\/p>\n

Routing socket\u662f\u7528\u6237\u6001\u8fdb\u7a0b\u7528\u6765\u5411\u5185\u6838\u4e2d\u7684\u8def\u7531\u8868\u589e\u52a0\u6216\u8005\u5220\u9664\u8def\u7531\u4fe1\u606f\u7528\u7684\u3002\u5728Linux\u7cfb\u7edf\u4e2d\uff0cnetlink socket\u901a\u8fc7\u534f\u8bae\u7c7b\u578bNETLINK_ROUTE\u5b9e\u73b0\u4e86\u4e0e<\/p>\n

Routing socket\u76f8\u540c\u7684\u529f\u80fd\uff0c\u53ef\u4ee5\u8bf4\uff0cnetlink socket\u63d0\u4f9b\u4e86BSD Routing socket\u529f\u80fd\u7684\u8d85\u96c6\u3002<\/p>\n

Netlink Socket \u7684API<\/strong><\/h2>\n

\u6807\u51c6\u7684socket API\u51fd\u6570-
\n
\nsocket(), sendmsg(), recvmsg()\u548cclose()
\n<\/coolcode><\/p>\n

– \u90fd\u80fd\u591f\u88ab\u7528\u6237\u6001\u7a0b\u5e8f\u76f4\u63a5\u8c03\u7528\u6765\u8bbf\u95eenetlink socket.\u4f60\u53ef\u4ee5\u8bbf\u95eeman\u624b\u518c\u6765\u83b7\u53d6\u8fd9\u4e9b\u51fd\u6570\u7684\u8be6\u7ec6\u5b9a\u4e49\u3002\u5728\u672c\u6587\uff0c\u6211\u4eec\u53ea\u8ba8\u8bba\u600e\u6837\u5728netlink socket\u7684\u4e0a\u4e0b\u6587<\/p>\n

\u4e2d\u4e3a\u8fd9\u4e9b\u51fd\u6570\u9009\u62e9\u53c2\u6570\u3002\u8fd9\u4e9bAPI\u5bf9\u4e8e\u4f7f\u7528TCP\/IP socket\u5199\u8fc7\u4e00\u4e9b\u7b80\u5355\u7f51\u7edc\u7a0b\u5e8f\u7684\u8bfb\u8005\u6765\u8bf4\u5e94\u8be5\u5f88\u719f\u6089\u4e86\u3002
\n\u4f7f\u7528socket()\u51fd\u6570\u521b\u5efa\u4e00\u4e2asocket\uff0c\u8f93\u5165\uff1a
\n
\nint socket(int domain, int type, int protocol)
\n <\/coolcode><\/p>\n

socket\u57df(\u5730\u5740\u65cf)\u662fAF_NETLINK,socket\u7684\u7c7b\u578b\u662fSOCK_RAW\u6216\u8005SOCK_DGRAM,\u56e0\u4e3anetlink\u662f\u4e00\u79cd\u9762\u5411\u6570\u636e\u5305\u7684\u670d\u52a1\u3002
\n\u534f\u8bae\u7c7b\u578b\u9009\u62e9netlink\u8981\u4f7f\u7528\u7684\u7c7b\u578b\u5373\u53ef\u3002\u4e0b\u9762\u662f\u4e00\u4e9b\u9884\u5b9a\u4e49\u7684netlink\u534f\u8bae\u7c7b\u578b\uff1a<\/p>\n


\nNETLINK_ROUTE, NETLINK_FIREWALL, NETLINK_ARPD, NETLINK_ROUTE6
\n\u548c NETLINK_IP6_FW.
\n<\/coolcode>
\n\u4f60\u540c\u6837\u53ef\u4ee5\u5f88\u8f7b\u677e\u7684\u5728netlink.h\u4e2d\u6dfb\u52a0\u81ea\u5b9a\u4e49\u7684\u534f\u8bae\u7c7b\u578b\u3002<\/p>\n

\u6bcf\u4e2anetlink\u534f\u8bae\u7c7b\u578b\u53ef\u4ee5\u5b9a\u4e49\u9ad8\u8fbe32\u4e2a\u591a\u70b9\u4f20\u8f93\u7684\u7ec4\u3002\u6bcf\u4e2a\u7ec4\u7528\u4e00\u4e2a\u6bd4\u7279\u4f4d\u6765\u8868\u793a\uff0c1<
\nstruct sockaddr_nl
\n{
\n sa_family_t nl_family; \/* AF_NETLINK *\/
\n unsigned short nl_pad; \/* zero *\/
\n __u32 nl_pid; \/* process pid *\/
\n __u32 nl_groups; \/* mcast groups mask *\/
\n} nladdr; <\/p>\n

<\/coolcode>
\n\u5f53\u4e0a\u9762\u7684\u7ed3\u6784\u4f53\u88abbind()\u51fd\u6570\u8c03\u7528\u65f6\uff0csockaddr_nl\u7684nl_pid\u5c5e\u6027\u7684\u503c\u53ef\u4ee5\u8bbe\u7f6e\u4e3a\u8bbf\u95eenetlink socket\u7684\u5f53\u524d\u8fdb\u7a0b\u7684PID\uff0cnl_pid\u4f5c\u4e3a\u8fd9\u4e2anetlink socket\u7684\u672c<\/p>\n

\u5730\u5730\u5740\u3002\u5e94\u7528\u7a0b\u5e8f\u5e94\u8be5\u9009\u62e9\u4e00\u4e2a\u552f\u4e00\u768432\u4f4d\u6574\u6570\u6765\u586b\u5145nl_pid\u7684\u503c\u3002<\/p>\n


\nNL_PID \u516c\u5f0f 1: nl_pid = getpid();
\n<\/coolcode>
\n\u516c\u5f0f\u4e00\u4f7f\u7528\u8fdb\u7a0b\u7684PID\u4f5c\u4e3anl_pid\u7684\u503c\uff0c\u5982\u679c\u8fd9\u4e2a\u8fdb\u7a0b\u53ea\u9700\u8981\u4e00\u4e2a\u8be5\u7c7b\u578b\u534f\u8bae\u7684netlink socket\u7684\u8bdd\uff0c\u9009\u7528\u8fdb\u7a0bpid\u4f5c\u4e3anl_pid\u662f\u4e00\u4e2a\u5f88\u81ea\u7136\u7684\u505a\u6cd5\u3002
\n\u6362\u4e00\u79cd\u60c5\u5f62\uff0c\u5982\u679c\u4e00\u4e2a\u8fdb\u7a0b\u7684\u591a\u4e2a\u7ebf\u7a0b\u60f3\u8981\u521b\u5efa\u5c5e\u4e8e\u5404\u4e2a\u7ebf\u7a0b\u7684\u76f8\u540c\u534f\u8bae\u7c7b\u578b\u7684netlink socket\u7684\u8bdd\uff0c\u516c\u5f0f\u4e8c\u53ef\u4ee5\u7528\u6765\u4e3a\u6bcf\u4e2a\u7ebf\u7a0b\u7684netlink socket\u4ea7\u751f<\/p>\n

nl_pid\u503c\u3002
\n
\nNL_PID \u516c\u5f0f 2: pthread_self() << 16 | getpid();\n<\/coolcode>
\n\u91c7\u7528\u8fd9\u79cd\u65b9\u6cd5\uff0c\u540c\u4e00\u8fdb\u7a0b\u7684\u4e0d\u540c\u7ebf\u7a0b\u90fd\u80fd\u83b7\u53d6\u5c5e\u4e8e\u5b83\u4eec\u7684\u76f8\u540c\u534f\u8bae\u7c7b\u578b\u7684\u4e0d\u540cnetlink socket\u3002\u4e8b\u5b9e\u4e0a\uff0c\u5373\u4fbf\u662f\u5728\u4e00\u4e2a\u5355\u72ec\u7684\u7ebf\u7a0b\u91cc\uff0c\u4e5f\u53ef\u80fd\u9700\u8981\u521b\u5efa\u540c\u4e00\u534f\u8bae<\/p>\n

\u7c7b\u578b\u7684\u591a\u4e2anetlink socket\u3002\u6240\u4ee5\u5f00\u53d1\u4eba\u5458\u9700\u8981\u66f4\u591a\u806a\u660e\u624d\u667a\u53bb\u521b\u5efa\u4e0d\u540c\u7684nl_pid\u503c\uff0c\u7136\u800c\u672c\u6587\u4e2d\u4e0d\u4f1a\u5c31\u5982\u4f55\u521b\u5efa\u591a\u4e2a\u4e0d\u540c\u7684nl_pid\u7684\u503c\u8fdb\u884c\u8fc7\u591a\u7684\u8ba8\u8bba
\n\u5982\u679c\u5e94\u7528\u7a0b\u5e8f\u60f3\u8981\u63a5\u6536\u7279\u5b9a\u534f\u8bae\u7c7b\u578b\u7684\u53d1\u5f80\u6307\u5b9a\u591a\u64ad\u7ec4\u7684netlink\u6d88\u606f\u7684\u8bdd\uff0c\u6240\u6709\u63a5\u6536\u7ec4\u7684\u6bd4\u7279\u4f4d\u5e94\u8be5\u8fdb\u884c\u4e0e\u8fd0\u7b97\uff0c\u5f62\u6210sockaddr_nl\u7684 nl_groups\u57df\u7684\u503c\u3002\u5426<\/p>\n

\u5219\u7684\u8bdd\uff0cnl_groups\u5e94\u8be5\u8bbe\u7f6e\u4e3a0\uff0c\u4ee5\u4fbf\u5e94\u7528\u7a0b\u5e8f\u53ea\u80fd\u591f\u6536\u5230\u53d1\u9001\u7ed9\u5b83\u7684netlink\u6d88\u606f\u3002\u5728\u586b\u5145\u5b8c\u7ed3\u6784\u4f53 nladdr\u540e\uff0c\u4f5c\u5982\u4e0b\u7684\u7ed1\u5b9a\u5de5\u4f5c:
\n
\nbind(fd, (struct sockaddr*)&nladdr, sizeof(nladdr));
\n<\/coolcode><\/p>\n

\u53d1\u9001netlink \u6d88\u606f<\/strong><\/h2>\n

\u4e3a\u4e86\u80fd\u591f\u628a\u4e00\u4e2anetlink\u6d88\u606f\u53d1\u9001\u7ed9\u5185\u6838\u6216\u8005\u522b\u7684\u7528\u6237\u8fdb\u7a0b\uff0c\u7c7b\u4f3c\u4e8eUDP\u6570\u636e\u5305\u53d1\u9001\u7684sendmsg()\u51fd\u6570\u4e00\u6837\uff0c\u6211\u4eec\u9700\u8981\u53e6\u5916\u4e00\u4e2a\u7ed3\u6784\u4f53 struct sockaddr_nl <\/p>\n

nladdr\u4f5c\u4e3a\u76ee\u7684\u5730\u5740\u3002\u5982\u679c\u8fd9\u4e2anetlink\u6d88\u606f\u662f\u53d1\u5f80\u5185\u6838\u7684\u8bdd\uff0cnl_pid\u5c5e\u6027\u548cnl_groups\u5c5e\u6027\u90fd\u5e94\u8be5\u8bbe\u7f6e\u4e3a0\u3002
\n\u5982\u679c\u8fd9\u4e2a\u6d88\u606f\u662f\u53d1\u5f80\u53e6\u5916\u4e00\u4e2a\u8fdb\u7a0b\u7684\u5355\u70b9\u4f20\u8f93\u6d88\u606f\uff0cnl_pid\u5e94\u8be5\u8bbe\u7f6e\u4e3a\u63a5\u6536\u8005\u8fdb\u7a0b\u7684PID\uff0cnl_groups\u5e94\u8be5\u8bbe\u7f6e\u4e3a0\uff0c\u5047\u8bbe\u7cfb\u7edf\u4e2d\u4f7f\u7528\u4e86\u516c\u5f0f1\u3002
\n\u5982\u679c\u6d88\u606f\u662f\u53d1\u5f80\u4e00\u4e2a\u6216\u8005\u591a\u4e2a\u591a\u64ad\u7ec4\u7684\u8bdd\uff0c\u5e94\u8be5\u7528\u6240\u6709\u76ee\u7684\u591a\u64ad\u7ec4\u7684\u6bd4\u7279\u4f4d\u4e0e\u8fd0\u7b97\u5f62\u6210nl_groups\u7684\u503c\u3002\u7136\u540e\u6211\u4eec\u5c31\u53ef\u4ee5\u5c06netlink\u5730\u5740\u5e94\u7528\u5230\u7ed3\u6784\u4f53struct <\/p>\n

msghdr msg\u4e2d\uff0c\u4f9b\u51fd\u6570sendmsg()\u6765\u8c03\u7528\uff1a
\n
\nstruct msghdr msg;
\nmsg.msg_name = (void *)&(nladdr);
\nmsg.msg_namelen = sizeof(nladdr);
\n<\/coolcode>
\nnetlink\u6d88\u606f\u540c\u6837\u4e5f\u9700\u8981\u5b83\u81ea\u8eab\u7684\u6d88\u606f\u5934\uff0c\u8fd9\u6837\u505a\u662f\u4e3a\u4e86\u7ed9\u6240\u6709\u534f\u8bae\u7c7b\u578b\u7684netlink\u6d88\u606f\u63d0\u4f9b\u4e00\u4e2a\u901a\u7528\u7684\u80cc\u666f\u3002
\n\u7531\u4e8elinux\u5185\u6838\u7684netlink\u90e8\u5206\u603b\u662f\u8ba4\u4e3a\u5728\u6bcf\u4e2anetlink\u6d88\u606f\u4f53\u4e2d\u5df2\u7ecf\u5305\u542b\u4e86\u4e0b\u9762\u7684\u6d88\u606f\u5934\uff0c\u6240\u4ee5\u6bcf\u4e2a\u5e94\u7528\u7a0b\u5e8f\u5728\u53d1\u9001netlink\u6d88\u606f\u4e4b\u524d\u9700\u8981\u63d0\u4f9b\u8fd9\u4e2a\u5934\u4fe1\u606f\uff1a
\n
\nstruct nlmsghdr
\n{
\n __u32 nlmsg_len; \/* Length of message *\/
\n __u16 nlmsg_type; \/* Message type*\/
\n __u16 nlmsg_flags; \/* Additional flags *\/
\n __u32 nlmsg_seq; \/* Sequence number *\/
\n __u32 nlmsg_pid; \/* Sending process PID *\/
\n};<\/p>\n

<\/coolcode><\/p>\n

nlmsg_len \u9700\u8981\u7528netlink \u6d88\u606f\u4f53\u7684\u603b\u957f\u5ea6\u6765\u586b\u5145\uff0c\u5305\u542b\u5934\u4fe1\u606f\u5728\u5185\uff0c\u8fd9\u4e2a\u662fnetlink\u6838\u5fc3\u9700\u8981\u7684\u4fe1\u606f\u3002mlmsg_type\u53ef\u4ee5\u88ab\u5e94\u7528\u7a0b\u5e8f\u6240\u7528\uff0c\u5b83\u5bf9\u4e8enetlink\u6838\u5fc3<\/p>\n

\u6765\u8bf4\u662f\u4e00\u4e2a\u900f\u660e\u7684\u503c\u3002Nsmsg_flags \u7528\u6765\u8be5\u5bf9\u6d88\u606f\u4f53\u8fdb\u884c\u53e6\u5916\u7684\u63a7\u5236\uff0c\u4f1a\u88abnetlink\u6838\u5fc3\u4ee3\u7801\u8bfb\u53d6\u5e76\u66f4\u65b0\u3002Nlmsg_seq\u548cnlmsg_pid\u540c\u6837\u5bf9\u4e8enetlink\u6838\u5fc3\u90e8\u5206\u6765<\/p>\n

\u8bf4\u662f\u900f\u660e\u7684\uff0c\u5e94\u7528\u7a0b\u5e8f\u7528\u5b83\u4eec\u6765\u8ddf\u8e2a\u6d88\u606f\u3002
\n\u56e0\u6b64\uff0c\u4e00\u4e2anetlink\u6d88\u606f\u4f53\u7531nlmsghdr\u548c\u6d88\u606f\u7684payload\u90e8\u5206\u7ec4\u6210\u3002\u4e00\u65e6\u8f93\u5165\u4e00\u4e2a\u6d88\u606f\uff0c\u5b83\u5c31\u4f1a\u8fdb\u5165\u4e00\u4e2a\u88abnlh\u6307\u9488\u6307\u5411\u7684\u7f13\u51b2\u533a\u3002\u6211\u4eec\u540c\u6837\u53ef\u4ee5\u628a\u6d88\u606f\u53d1\u9001\u4e2a\u7ed3<\/p>\n

\u6784\u4f53struct msghdr msg:
\n
\nstruct iovec iov;
\niov.iov_base = (void *)nlh;
\niov.iov_len = nlh->nlmsg_len;
\nmsg.msg_iov = &iov;
\nmsg.msg_iovlen = 1;
\n<\/coolcode>
\n\u5728\u5b8c\u6210\u4e86\u4ee5\u4e0a\u6b65\u9aa4\u540e\uff0c\u8c03\u7528\u4e00\u6b21sendmsg()\u51fd\u6570\u5c31\u80fd\u628anetlink\u6d88\u606f\u53d1\u9001\u51fa\u53bb\uff1a
\n
\nsendmsg(fd, &msg, 0);
\n <\/coolcode><\/p>\n

\u63a5\u6536netlink\u6d88\u606f<\/strong><\/h2>\n

\u63a5\u6536\u7a0b\u5e8f\u9700\u8981\u7533\u8bf7\u8db3\u591f\u5927\u7684\u7a7a\u95f4\u6765\u5b58\u50a8netlink\u6d88\u606f\u5934\u548c\u6d88\u606f\u7684payload\u90e8\u5206\u3002\u5b83\u4f1a\u7528\u5982\u4e0b\u7684\u65b9\u5f0f\u586b\u5145\u7ed3\u6784\u4f53 struct msghdr msg,\u7136\u540e\u4f7f\u7528\u6807\u51c6\u51fd\u6570\u63a5\u53e3<\/p>\n

recvmsg()\u6765\u63a5\u6536netlink\u6d88\u606f\uff0c\u5047\u8bbenlh\u6307\u5411\u7f13\u51b2\u533a\uff1a
\n
\nstruct sockaddr_nl nladdr;
\nstruct msghdr msg;
\nstruct iovec iov;<\/p>\n

iov.iov_base = (void *)nlh;
\niov.iov_len = MAX_NL_MSG_LEN;
\nmsg.msg_name = (void *)&(nladdr);
\nmsg.msg_namelen = sizeof(nladdr);<\/p>\n

msg.msg_iov = &iov;
\nmsg.msg_iovlen = 1;
\nrecvmsg(fd, &msg, 0);
\n <\/coolcode>
\n\u5f53\u6d88\u606f\u6b63\u786e\u63a5\u6536\u540e\uff0cnlh\u5e94\u8be5\u6307\u5411\u521a\u521a\u63a5\u6536\u5230\u7684netlink\u6d88\u606f\u7684\u5934\u90e8\u5206\u3002Nladdr\u5e94\u8be5\u5305\u542b\u63a5\u6536\u5230\u6d88\u606f\u4f53\u7684\u76ee\u7684\u5730\u4fe1\u606f\uff0c\u8fd9\u4e2a\u76ee\u7684\u5730\u4fe1\u606f\u7531pid\u548c\u6d88\u606f\u5c06\u8981\u53d1\u5f80\u7684\u591a<\/p>\n

\u64ad\u7ec4\u7684\u503c\u7ec4\u6210\u3002Netlink.h\u4e2d\u7684\u5b8f\u5b9a\u4e49NLMSG_DATA(nlh)\u8fd4\u56de\u6307\u5411netlink\u6d88\u606f\u4f53\u7684payload\u7684\u6307\u9488\u3002\u8c03\u7528
\n
\nclose(fd)
\n<\/coolcode>
\n\u5c31\u53ef\u4ee5\u5173\u95ed\u6389fd\u63cf\u8ff0\u7b26\u4ee3\u8868\u7684netlink socket.<\/p>\n

\u5185\u6838\u7a7a\u95f4\u7684netlink API\u63a5\u53e3<\/strong><\/h2>\n

\u5185\u6838\u7a7a\u95f4\u7684netlink API\u662f\u7531\u5185\u6838\u4e2d\u7684netlink\u6838\u5fc3\u4ee3\u7801\u652f\u6301\u7684\uff0c\u5728net\/core\/af_netlink.c\u4e2d\u5b9e\u73b0\u3002\u4ece\u5185\u6838\u7684\u89d2\u5ea6\u6765\u8bf4\uff0cAPI\u63a5\u53e3\u4e0e\u7528\u6237\u7a7a\u95f4\u7684 API\u662f\u4e0d\u4e00<\/p>\n

\u6837\u7684\u3002\u5185\u6838\u6a21\u5757\u901a\u8fc7\u8fd9\u4e9bAPI\u8bbf\u95eenetlink socket\u5e76\u4e14\u4e0e\u7528\u6237\u7a7a\u95f4\u7684\u7a0b\u5e8f\u8fdb\u884c\u901a\u8baf\u3002\u5982\u679c\u4f60\u4e0d\u60f3\u4f7f\u7528netlink\u9884\u5b9a\u4e49\u597d\u7684\u534f\u8bae\u7c7b\u578b\u7684\u8bdd\uff0c\u53ef\u4ee5\u5728netlink.h\u4e2d\u6dfb\u52a0<\/p>\n

\u4e00\u4e2a\u81ea\u5b9a\u4e49\u7684\u534f\u8bae\u7c7b\u578b\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u5728netlink.h\u4e2d\u63d2\u5165\u4e0b\u9762\u7684\u4ee3\u7801\u884c\uff0c\u6dfb\u52a0\u4e00\u4e2a\u6d4b\u8bd5\u7528\u7684\u534f\u8bae\u7c7b\u578b\uff1a
\n
\n#define NETLINK_TEST 17
\n<\/coolcode>
\n\u7136\u540e\uff0c\u5c31\u53ef\u4ee5\u5728linux\u5185\u6838\u7684\u4efb\u4f55\u90e8\u5206\u8bbf\u95ee\u8fd9\u4e2a\u534f\u8bae\u7c7b\u578b\u4e86\u3002
\n\u5728\u7528\u6237\u7a7a\u95f4\uff0c\u6211\u4eec\u901a\u8fc7socket()\u8c03\u7528\u6765\u521b\u5efa\u4e00\u4e2anetlink socket,\u4f46\u662f\u5728\u5185\u6838\u7a7a\u95f4\uff0c\u6211\u4eec\u8c03\u7528\u5982\u4e0b\u7684API\uff1a
\n
\nstruct sock * netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len));
\n<\/coolcode>
\n\u53c2\u6570uint\u662fnetlink\u534f\u8bae\u7c7b\u578b\uff0c\u4f8b\u5982NETLINK_TEST\u3002\u51fd\u6570\u6307\u9488\uff0cinput,\u662fnetlink socket\u5728\u6536\u5230\u6d88\u606f\u65f6\u8c03\u7528\u7684\u5904\u7406\u6d88\u606f\u7684\u56de\u8c03\u51fd\u6570\u6307\u9488\u3002
\n\u5728\u5185\u6838\u521b\u5efa\u4e86\u4e00\u4e2aNETLINK_TEST\u7c7b\u578b\u7684netlink socket\u540e\uff0c\u65e0\u8bba\u4ec0\u4e48\u65f6\u5019\uff0c\u53ea\u8981\u7528\u6237\u7a0b\u5e8f\u53d1\u9001\u4e00\u4e2aNETLINK_TEST\u7c7b\u578b\u7684netlink\u6d88\u606f\u5230\u5185\u6838\u7684\u8bdd\uff0c\u901a\u8fc7 <\/p>\n

netlink_kernel_create()\u51fd\u6570\u6ce8\u518c\u7684\u56de\u8c03\u51fd\u6570input()\u90fd\u4f1a\u88ab\u8c03\u7528\u3002\u4e0b\u9762\u662f\u4e00\u4e2a\u5b9e\u73b0\u4e86\u6d88\u606f\u5904\u7406\u51fd\u6570input\u7684\u4f8b\u5b50\u3002<\/p>\n


\nvoid input (struct sock *sk, int len)
\n{
\n struct sk_buff *skb;
\n struct nlmsghdr *nlh = NULL;
\n u8 *payload = NULL;<\/p>\n

while ((skb = skb_dequeue(&sk->receive_queue))!= NULL)
\n {
\n \/* process netlink message pointed by skb->data *\/
\n nlh = (struct nlmsghdr *)skb->data;
\n payload = NLMSG_DATA(nlh);
\n \/* process netlink message with header pointed by
\n * nlh and payload pointed by payload
\n *\/
\n }
\n}<\/p>\n

<\/coolcode><\/p>\n

\u56de\u8c03\u51fd\u6570input()\u662f\u5728\u53d1\u9001\u8fdb\u7a0b\u7684\u7cfb\u7edf\u8c03\u7528sendmsg()\u7684\u4e0a\u4e0b\u6587\u88ab\u8c03\u7528\u7684\u3002\u5982\u679cinput\u51fd\u6570\u4e2d\u5904\u7406\u6d88\u606f\u5f88\u5feb\u7684\u8bdd\uff0c\u4e00\u5207\u90fd\u6ca1\u6709\u95ee\u9898\u3002\u4f46\u662f\u5982\u679c\u5904\u7406netlink\u6d88\u606f\u82b1<\/p>\n

\u8d39\u5f88\u957f\u65f6\u95f4\u7684\u8bdd\uff0c\u6211\u4eec\u5219\u5e0c\u671b\u628a\u6d88\u606f\u7684\u5904\u7406\u90e8\u5206\u653e\u5728input()\u51fd\u6570\u7684\u5916\u9762\uff0c\u56e0\u4e3a\u957f\u65f6\u95f4\u7684\u6d88\u606f\u5904\u7406\u8fc7\u7a0b\u53ef\u80fd\u4f1a\u963b\u6b62\u5176\u5b83\u7cfb\u7edf\u8c03\u7528\u8fdb\u5165\u5185\u6838\u3002\u53d6\u800c\u4ee3\u4e4b\uff0c\u6211\u4eec\u53ef\u4ee5\u727a<\/p>\n

\u7272\u4e00\u4e2a\u5185\u6838\u7ebf\u7a0b\u6765\u5b8c\u6210\u540e\u7eed\u7684\u65e0\u9650\u7684\u7684\u5904\u7406\u52a8\u4f5c\u3002
\n\u4f7f\u7528
\n
\nskb = skb_recv_datagram(nl_sk)
\n<\/coolcode><\/p>\n

\u6765\u63a5\u6536\u6d88\u606f\u3002nl_sk\u662fnetlink_kernel_create()\u51fd\u6570\u8fd4\u56de\u7684netlink socket,\u7136\u540e\uff0c\u53ea\u9700\u8981\u5904\u7406skb->data\u6307\u9488\u6307\u5411\u7684netlink\u6d88\u606f\u5c31\u53ef\u4ee5\u4e86\u3002
\n\u8fd9\u4e2a\u5185\u6838\u7ebf\u7a0b\u4f1a\u5728nl_sk\u4e2d\u6ca1\u6709\u6d88\u606f\u7684\u65f6\u5019\u7761\u7720\u3002\u56e0\u6b64\uff0c\u5728\u56de\u8c03\u51fd\u6570input()\u4e2d\u6211\u4eec\u8981\u505a\u7684\u4e8b\u60c5\u5c31\u662f\u5524\u9192\u7761\u7720\u7684\u5185\u6838\u7ebf\u7a0b\uff0c\u50cf\u8fd9\u6837\u7684\u65b9\u5f0f:
\n
\nvoid input (struct sock *sk, int len)
\n{
\n wake_up_interruptible(sk->sleep);
\n}
\n<\/coolcode>
\n\u8fd9\u5c31\u662f\u4e00\u4e2a\u5347\u7ea7\u7248\u7684\u5185\u6838\u4e0e\u7528\u6237\u7a7a\u95f4\u7684\u901a\u8baf\u6a21\u578b\uff0c\u5b83\u63d0\u9ad8\u4e86\u4e0a\u4e0b\u6587\u5207\u6362\u7684\u7c92\u5ea6\u3002
\n\u4ece\u5185\u6838\u4e2d\u53d1\u9001netlink\u6d88\u606f
\n\u5c31\u50cf\u4ece\u7528\u6237\u7a7a\u95f4\u53d1\u9001\u6d88\u606f\u4e00\u6837\uff0c\u5185\u6838\u5728\u53d1\u9001netlink\u6d88\u606f\u65f6\u4e5f\u9700\u8981\u8bbe\u7f6e\u6e90netlink\u5730\u5740\u548c\u76ee\u7684netlink\u5730\u5740\u3002\u5047\u8bbe\u7ed3\u6784\u4f53struct sk_buff * skb\u6307\u5411\u5b58\u50a8\u7740\u8981\u53d1\u9001<\/p>\n

\u7684netlink\u6d88\u606f\u7684\u7f13\u51b2\u533a\uff0c\u6e90\u5730\u5740\u53ef\u4ee5\u8fd9\u6837\u8bbe\u7f6e:
\n
\nNETLINK_CB(skb).groups = local_groups;
\nNETLINK_CB(skb).pid = 0; \/* from kernel *\/
\n\u76ee\u7684\u5730\u5740\u53ef\u4ee5\u8fd9\u6837\u8bbe\u7f6e:
\nNETLINK_CB(skb).dst_groups = dst_groups;
\nNETLINK_CB(skb).dst_pid = dst_pid;
\n<\/coolcode><\/p>\n

\u8fd9\u4e9b\u4fe1\u606f\u5e76\u4e0d\u5b58\u50a8\u5728 skb->data\u4e2d\uff0c\u76f8\u53cd\uff0c\u5b83\u4eec\u5b58\u50a8\u5728socket\u7f13\u51b2\u533a\u7684netlink\u63a7\u5236\u5757skb\u4e2d.
\n\u53d1\u9001\u4e00\u4e2a\u5355\u64ad\u6d88\u606f\uff0c\u4f7f\u7528:
\n
\nint netlink_unicast(struct sock *ssk, struct sk_buff *skb, u32 pid, int nonblock);
\n <\/coolcode>
\nssk\u662fby netlink_kernel_create()\u51fd\u6570\u8fd4\u56de\u7684netlink socket, skb->data\u6307\u5411\u9700\u8981\u53d1\u9001\u7684netlink\u6d88\u606f\u4f53\uff0c\u5982\u679c\u4f7f\u7528\u516c\u5f0f\u4e00\u7684\u8bdd\uff0cpid\u662f\u63a5\u6536\u7a0b\u5e8f\u7684pid\uff0c<\/p>\n

noblock\u8868\u660e\u5f53\u63a5\u6536\u7f13\u51b2\u533a\u4e0d\u53ef\u7528\u65f6\u662f\u5426\u5e94\u8be5\u963b\u585e\u8fd8\u662f\u7acb\u5373\u8fd4\u56de\u4e00\u4e2a\u5931\u8d25\u4fe1\u606f\u3002
\n\u4f60\u540c\u6837\u53ef\u4ee5\u4ece\u5185\u6838\u53d1\u9001\u4e00\u4e2a\u591a\u64ad\u6d88\u606f\u3002\u4e0b\u9762\u7684\u51fd\u6570\u540c\u65f6\u628a\u4e00\u4e2anetlink\u6d88\u606f\u53d1\u9001\u7ed9pid\u6307\u5b9a\u7684\u8fdb\u7a0b\u548cgroup\u6807\u8bc6\u7684\u591a\u4e2a\u7ec4\u3002
\n
\nvoid netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid, u32 group, int allocation);
\n <\/coolcode>
\ngroup\u7684\u503c\u662f\u63a5\u6536\u6d88\u606f\u7684\u5404\u4e2a\u7ec4\u7684\u6bd4\u7279\u4f4d\u8fdb\u884c\u4e0e\u8fd0\u7b97\u7684\u7ed3\u679c\u3002Allocation\u662f\u5185\u6838\u5185\u5b58\u7684\u7533\u8bf7\u7c7b\u578b\u3002\u901a\u5e38\u60c5\u51b5\u4e0b\u5728\u4e2d\u65ad\u4e0a\u4e0b\u6587\u4f7f\u7528 GFP_ATOMIC,\u5426\u5219\u4f7f\u7528<\/p>\n

GFP_KERNEL\u3002\u8fd9\u662f\u7531\u4e8e\u53d1\u9001\u591a\u64ad\u6d88\u606f\u65f6\uff0cAPI\u53ef\u80fd\u9700\u8981\u7533\u8bf7\u4e00\u4e2a\u6216\u8005\u591a\u4e2asocket\u7f13\u51b2\u533a\u5e76\u8fdb\u884c\u62f7\u8d1d\u6240\u5f15\u8d77\u7684\u3002
\n\u4ece\u5185\u6838\u7a7a\u95f4\u5173\u95ednetlink socket
\nnetlink_kernel_create()\u51fd\u6570\u8fd4\u56de\u7684netlink socket\u4e3astruct sock *nl_sk\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u8bbf\u95ee\u4e0b\u9762\u7684API\u6765\u4ece\u5185\u6838\u7a7a\u95f4\u5173\u95ed\u8fd9\u4e2anetlink socket:
\nsock_release(nl_sk->socket);
\n\u5230\u76ee\u524d\u4e3a\u6b62\uff0c\u6211\u4eec\u5df2\u7ecf\u6f14\u793a\u4e86netlink\u7f16\u7a0b\u6982\u5ff5\u7684\u6700\u5c0f\u4ee3\u7801\u6846\u67b6\u3002\u63a5\u7740\u6211\u4eec\u4f1a\u4f7f\u7528NETLINK_TEST\u534f\u8bae\u7c7b\u578b\uff0c\u5e76\u4e14\u5047\u8bbe\u5b83\u5df2\u7ecf\u88ab\u6dfb\u52a0\u5230\u5185\u6838\u5934\u6587\u4ef6\u4e2d\u4e86\u3002\u8fd9\u91cc\u5217\u4e3e<\/p>\n

\u7684\u5185\u6838\u6a21\u5757\u4ee3\u7801\u53ea\u662f\u4e0enetlink\u76f8\u5173\u7684\uff0c\u6240\u4ee5\uff0c\u4f60\u5e94\u8be5\u628a\u5b83\u63d2\u5165\u5230\u4e00\u4e2a\u5b8c\u6574\u7684\u5185\u6838\u6a21\u5757\u4ee3\u7801\u5f53\u4e2d\u53bb\uff0c\u8fd9\u6837\u7684\u5b8c\u6574\u4ee3\u7801\u5728\u5176\u5b83\u4ee3\u7801\u4e2d\u53ef\u4ee5\u627e\u5230\u5f88\u591a\u3002<\/p>\n

\u5185\u6838\u4e0e\u7528\u6237\u7a7a\u95f4\u7684\u5355\u5de5\u901a\u8baf<\/strong><\/h2>\n

\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u4e00\u4e2a\u7528\u6237\u6001\u8fdb\u7a0b\u53d1\u9001\u4e00\u4e2anetlink\u6d88\u606f\u7ed9\u5185\u6838\u6a21\u5757\uff0c\u5185\u6838\u6a21\u5757\u628a\u6d88\u606f\u56de\u9001\u7ed9\u53d1\u9001\u8fdb\u7a0b\uff0c\u4e0b\u9762\u662f\u7528\u6237\u6001\u7684\u4ee3\u7801\uff1a
\n
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include \n#include \n

#define NETLINK_TEST 17
\n#define MAX_PAYLOAD 1024 \/* maximum payload size*\/
\nstruct sockaddr_nl src_addr, dest_addr;
\nstruct nlmsghdr *nlh = NULL;
\nstruct iovec iov;
\nint sock_fd;
\nstruct msghdr msg;<\/p>\n

int main(int argc, char* argv[])
\n{
\n sock_fd = socket(PF_NETLINK, SOCK_RAW,NETLINK_TEST);
\n memset(&msg, 0, sizeof(msg));
\n memset(&src_addr, 0, sizeof(src_addr));
\n src_addr.nl_family = AF_NETLINK;
\n src_addr.nl_pid = getpid(); \/* self pid *\/
\n src_addr.nl_groups = 0; \/* not in mcast groups *\/
\n bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr));
\n memset(&dest_addr, 0, sizeof(dest_addr));
\n dest_addr.nl_family = AF_NETLINK;
\n dest_addr.nl_pid = 0; \/* For Linux Kernel *\/
\n dest_addr.nl_groups = 0; \/* unicast *\/<\/p>\n

nlh=(struct nlmsghdr *)malloc(NLMSG_SPACE(MAX_PAYLOAD));
\n \/* Fill the netlink message header *\/
\n nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
\n nlh->nlmsg_pid = getpid(); \/* self pid *\/
\n nlh->nlmsg_flags = 0;
\n \/* Fill in the netlink message payload *\/
\n strcpy(NLMSG_DATA(nlh), “Hello you!”);<\/p>\n

iov.iov_base = (void *)nlh;
\n iov.iov_len = nlh->nlmsg_len;
\n msg.msg_name = (void *)&dest_addr;
\n msg.msg_namelen = sizeof(dest_addr);
\n msg.msg_iov = &iov;
\n msg.msg_iovlen = 1;<\/p>\n

sendmsg(sock_fd, &msg, 0);<\/p>\n

\/* Read message from kernel *\/
\n memset(nlh, 0, NLMSG_SPACE(MAX_PAYLOAD));
\n recvmsg(sock_fd, &msg, 0);
\n printf(” Received message payload: %s\\n”,
\n NLMSG_DATA(nlh));<\/p>\n

\/* Close Netlink Socket *\/
\n close(sock_fd);
\n}
\n<\/coolcode><\/p>\n

\u4e0b\u9762\u662f\u5185\u6838\u4ee3\u7801:
\n
\n#include \n#include \n#include \n#include \n#include
\n#include \n

#define NETLINK_TEST 17
\nstruct sock *nl_sk = NULL;
\nvoid nl_data_ready (struct sock *sk, int len)
\n{
\n wake_up_interruptible(sk->sk_sleep);
\n}<\/p>\n

void test_netlink(void)
\n{
\n struct sk_buff * skb = NULL;
\n struct nlmsghdr * nlh = NULL;
\n int err;
\n u32 pid;<\/p>\n

nl_sk = netlink_kernel_create(NETLINK_TEST, nl_data_ready);
\n \/* wait for message coming down from user-space *\/
\n skb = skb_recv_datagram(nl_sk, 0, 0, &err);<\/p>\n

nlh = (struct nlmsghdr *)skb->data;
\n printk(“%s: received netlink message payload:%s\\n”, __FUNCTION__, (char*)NLMSG_DATA(nlh));<\/p>\n

pid = nlh->nlmsg_pid; \/*pid of sending process *\/
\n NETLINK_CB(skb).groups = 0; \/* not in mcast group *\/
\n NETLINK_CB(skb).pid = 0; \/* from kernel *\/
\n NETLINK_CB(skb).dst_pid = pid;
\n NETLINK_CB(skb).dst_groups = 0; \/* unicast *\/
\n netlink_unicast(nl_sk, skb, pid, MSG_DONTWAIT);
\n sock_release(nl_sk->sk_socket);
\n}<\/p>\n

int init_module()
\n{
\n test_netlink();
\n return 0;
\n}
\nvoid cleanup_module( )
\n{
\n}
\nMODULE_LICENSE(“GPL”);
\nMODULE_AUTHOR(“duanjigang”);
\n<\/coolcode> <\/p>\n

\u5728\u52a0\u8f7d\u5b8c\u4e0a\u9762\u7684\u5185\u6838\u4ee3\u7801\u751f\u6210\u7684\u6a21\u5757\u4ee5\u540e\uff0c\u8fd0\u884c\u7528\u6237\u6001\u7a0b\u5e8f\uff0c\u53ef\u4ee5\u770b\u5230\u4e0b\u9762\u8f93\u51fa:
\n
\nReceived message payload: Hello you!
\n<\/coolcode>
\n\u5e76\u4e14\uff0c\u4e0b\u9762\u7684\u4fe1\u606f\u4f1a\u5728dmesg\u4e2d\u8f93\u51fa:
\n
\nnetlink_test: received netlink message payload:
\nHello you!
\n<\/coolcode><\/p>\n

\u5185\u6838\u4e0e\u7528\u6237\u7a7a\u95f4\u4e4b\u95f4\u7684\u591a\u70b9\u4f20\u8f93\u901a\u8baf<\/strong><\/h2>\n

\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0c\u4e24\u4e2a\u7528\u6237\u7a7a\u95f4\u7a0b\u5e8f\u76d1\u542c\u76f8\u540c\u7684netlink\u591a\u64ad\u7ec4\u3002\u5185\u6838\u6a21\u5757\u901a\u8fc7netlink socket\u5411\u8fd9\u4e2a\u7ec4\u53d1\u9001\u4e00\u4e2a\u6d88\u606f\uff0c\u6240\u6709\u7684\u5e94\u7528\u7a0b\u5e8f\u90fd\u6536\u5230\u4e86\u8fd9\u4e2a\u6d88\u606f\uff0c\u4e0b\u9762<\/p>\n

\u662f\u7528\u6237\u6001\u7684\u4ee3\u7801:
\n
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include
\n#include \n#include \n

#define NETLINK_TEST 17
\n#define MAX_PAYLOAD 1024 \/* maximum payload size*\/
\nstruct sockaddr_nl src_addr, dest_addr;
\nstruct nlmsghdr *nlh = NULL;
\nstruct iovec iov;
\nint sock_fd;
\nstruct msghdr msg;<\/p>\n

int main(int argc, char* argv[])
\n{<\/p>\n

sock_fd=socket(PF_NETLINK, SOCK_RAW, NETLINK_TEST);
\n memset(&src_addr, 0, sizeof(src_addr));
\n memset(&msg, 0, sizeof(msg));<\/p>\n

src_addr.nl_family = AF_NETLINK;
\n src_addr.nl_pid = getpid(); \/* self pid *\/
\n \/* interested in group 1<<0 *\/\n src_addr.nl_groups = 1;\n bind(sock_fd, (struct sockaddr*)&src_addr, sizeof(src_addr));\n memset(&dest_addr, 0, sizeof(dest_addr));\n nlh = (struct nlmsghdr *)malloc(NLMSG_SPACE(MAX_PAYLOAD));\n memset(nlh, 0, NLMSG_SPACE(MAX_PAYLOAD));\n\n iov.iov_base = (void *)nlh;\n iov.iov_len = NLMSG_SPACE(MAX_PAYLOAD);\n msg.msg_name = (void *)&dest_addr;\n msg.msg_namelen = sizeof(dest_addr);\n msg.msg_iov = &iov;\n msg.msg_iovlen = 1;\n\n printf(\"Waiting for message from kernel\\n\");\n\n \/* Read message from kernel *\/\n recvmsg(sock_fd, &msg, 0);\n\n printf(\"Received message payload: %s\\n\", NLMSG_DATA(nlh));\n close(sock_fd); \n} \n<\/coolcode>
\n\u4e0b\u9762\u662f\u5185\u6838\u6001\u7684\u4ee3\u7801:
\n
\n#include \n#include \n#include \n#include \n#include
\n#include \n

#define MAX_PAYLOAD 1024
\n#define NETLINK_TEST 17<\/p>\n

struct sock *nl_sk = NULL;<\/p>\n

void nl_data_ready (struct sock *sk, int len)
\n{
\n wake_up_interruptible(sk->sk_sleep);
\n}<\/p>\n

void test_netlink(void)
\n{
\n struct sk_buff *skb = NULL;
\n struct nlmsghdr *nlh;<\/p>\n

nl_sk = netlink_kernel_create(NETLINK_TEST, nl_data_ready);
\n skb = alloc_skb(NLMSG_SPACE(MAX_PAYLOAD),GFP_KERNEL);
\n nlh = (struct nlmsghdr *)skb->data;
\n nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
\n nlh->nlmsg_pid = 0; \/* from kernel *\/
\n nlh->nlmsg_flags = 0;
\n nlh = (struct nlmsghdr *) skb_put(skb, NLMSG_SPACE(MAX_PAYLOAD));
\n strcpy(NLMSG_DATA(nlh), “Greeting from kernel!”);
\n \/* sender is in group 1<<0 *\/\n NETLINK_CB(skb).groups = 1;\n NETLINK_CB(skb).pid = 0; \/* from kernel *\/\n NETLINK_CB(skb).dst_pid = 0; \/* multicast *\/\n \/* to mcast group 1<<0 *\/\n NETLINK_CB(skb).dst_groups = 1;\n \/*multicast the message to all listening processes*\/\n netlink_broadcast(nl_sk, skb, 0, 1, GFP_KERNEL);\n \/\/printk(\"%s\\n\", NLMSG_DATA(nlh));\n\n sock_release(nl_sk->sk_socket);
\n}<\/p>\n

int init_module()
\n{
\n test_netlink();
\n return 0;
\n}
\nvoid cleanup_module( )
\n{<\/p>\n

}
\nMODULE_LICENSE(“GPL”);
\nMODULE_AUTHOR(“duanjigang”);
\n<\/coolcode> <\/p>\n

\u5047\u8bbe\u7528\u6237\u6001\u7684\u4ee3\u7801\u7f16\u8bd1\u540e\u751f\u6210\u7684\u53ef\u6267\u884c\u7a0b\u5e8f\u4e3anl_recv,\u6211\u4eec\u53ef\u4ee5\u8fd0\u884cnl_recv\u7684\u4e24\u4e2a\u5b9e\u4f8b:
\n
\n.\/nl_recv &
\n<\/coolcode>
\n\u8f93\u51fa\u5982\u4e0b\uff1a
\n
\nWaiting for message from kernel
\n<\/coolcode>
\n\u8fd0\u884c\u53e6\u5916\u4e00\u4e2a\u5b9e\u4f8b:
\n.\/nl_recv &
\n\u8f93\u51fa\u5982\u4e0b:
\n
\nWaiting for message from kernel
\n<\/coolcode>
\n\u7136\u540e\uff0c\u5f53\u6211\u4eec\u52a0\u8f7d\u4e86\u5185\u6838\u6a21\u5757\u540e\uff0c\u4e24\u4e2anl_recv\u7684\u5b9e\u4f8b\u90fd\u5e94\u8be5\u4f1a\u8f93\u51fa\u5982\u4e0b\u7684\u6d88\u606f:
\n
\nReceived message payload: Greeting from kernel!
\nReceived message payload: Greeting from kernel!
\n<\/coolcode>
\n\u603b\u7ed3: Netlink socket\u662f\u7528\u6237\u7a7a\u95f4\u7a0b\u5e8f\u548c\u5185\u6838\u6a21\u5757\u4e4b\u95f4\u4e00\u79cd\u5f88\u7075\u6d3b\u7684\u901a\u8baf\u63a5\u53e3\u3002\u5b83\u4e3a\u5e94\u7528\u7a0b\u5e8f\u548c\u5185\u6838\u7a0b\u5e8f\u90fd\u63d0\u4f9b\u4e86\u4e00\u4e2a\u65b9\u4fbf\u4f7f\u7528\u7684API\u3002\u5b83\u8fd8\u63d0\u4f9b\u4e86\u9ad8\u7ea7\u7684\u901a\u8baf<\/p>\n

\u7279\u6027\uff0c\u6bd4\u5982\u5168\u53cc\u5de5\uff0c\u7f13\u51b2I\/O,\u591a\u70b9\u4f20\u9001\u548c\u5f02\u6b65\u901a\u8baf\uff0c\u8fd9\u4e9b\u90fd\u662f\u5176\u4ed6\u5185\u6838\/\u7528\u6237\u6001\u7684IPC\u6240\u4e0d\u5177\u6709\u7684\u529f\u80fd\u3002<\/p>\n

\u9644\u4ef6\u4ee3\u7801<\/h2>\n

\u672c\u6587\u793a\u4f8b\u4ee3\u7801<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

\u539f\u4f5c\u8005: Kevin Kaichuan He@2005-1-5 \u7ffb\u8bd1\u6574\u7406:duanjigang @2008-9… Read More »netlink socket \u7f16\u7a0b\u4e4bwhy & how<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","footnotes":""},"categories":[14],"tags":[],"class_list":["post-199","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"http:\/\/cmesoft.com\/index.php?rest_route=\/wp\/v2\/posts\/199","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/cmesoft.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/cmesoft.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/cmesoft.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/cmesoft.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=199"}],"version-history":[{"count":12,"href":"http:\/\/cmesoft.com\/index.php?rest_route=\/wp\/v2\/posts\/199\/revisions"}],"predecessor-version":[{"id":212,"href":"http:\/\/cmesoft.com\/index.php?rest_route=\/wp\/v2\/posts\/199\/revisions\/212"}],"wp:attachment":[{"href":"http:\/\/cmesoft.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=199"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/cmesoft.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=199"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/cmesoft.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=199"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}