{"id":1046,"date":"2012-05-26T03:49:17","date_gmt":"2012-05-25T18:49:17","guid":{"rendered":"http:\/\/blog.xcir.net\/?p=1046"},"modified":"2012-08-02T00:54:14","modified_gmt":"2012-08-01T15:54:14","slug":"how-to-hook-vcl-function-at-vmod","status":"publish","type":"post","link":"https:\/\/blog.xcir.net\/?p=1046","title":{"rendered":"How to hook VCL function at VMOD"},"content":{"rendered":"

VMOD processing want to before\/after VCL function processing.
\nBut, I do not want to write extra line.
\nHow to do it?<\/p>\n

\"\"<\/a>
\nCan be realized by the replace the pointer to sp->vcl->XXXX<\/strong>_func (VCL_XXXX<\/strong>)<\/p>\n

\"\"<\/a>
\nCan be added to the processing by replacing pointer<\/p>\n

\n\r\n\r\nstatic vcl_func_f         *vmod_redirect_Hook_vcl_error = NULL;\r\nstatic pthread_mutex_t    vmod_redirect_mutex = PTHREAD_MUTEX_INITIALIZER;\r\nstatic unsigned           hook_done = 0;\r\n\r\nstatic int vmod_Hook_vcl_error(struct sess *sp){\r\n\r\n    ....    \/\/write the processing\r\n\r\n    \/\/call original vcl_error\r\n    return(vmod_redirect_Hook_vcl_error(sp));\r\n\r\n}\r\n\r\nint\r\nvmod_location(struct sess *sp, int status, const char*p,...)\r\n{\r\n        \/\/vcl reload detection.\r\n        if(hook_done == 1\r\n           && sp->vcl->error_func != vmod_redirect_Hook_vcl_error ) hook_done = 0;\r\n\r\n        if(hook_done == 0){\r\n            \/\/lock to prevent another thread write\r\n            AZ(pthread_mutex_lock(&vmod_redirect_mutex));\r\n\r\n            if(hook_done == 0)\r\n            {\r\n                \/\/store the original vcl_error pointer\r\n                vmod_redirect_Hook_vcl_error = sp->vcl->error_func;\r\n\r\n                \/\/hook\r\n                sp->vcl->error_func = vmod_Hook_vcl_error;\r\n\r\n                hook_done = 1;\r\n            }\r\n            \/\/unlock\r\n            AZ(pthread_mutex_unlock(&vmod_redirect_mutex));\r\n        }\r\n\r\n    ....\r\n\r\n    return (status);\r\n}\r\n\n<\/pre>\n
(via:vmod_redirect<\/a>)<\/p>\n
Hook to vcl_error at vmod processing in first time.
\nbecause there is no way to write-access the pointer at vmod_Init.<\/p>\n
\"\"<\/a>
\n\"\"<\/a><\/p>\n
also, has locked using the mutex, because to prevent the loop by thread concurrent access.<\/p>\n
I hope that this code is of help to you.<\/p>\n
ATTENTION<\/strong>
\ndon’t use varnishadm’s command “vcl.use” and “vcl.discard” . because to the segfault or call to other vcl function. <\/p>\n
—
\nmodify(2012-08-01)
\nwhen you vcl reloaded, hook method be off.<\/p>\n
        
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\n","protected":false},"excerpt":{"rendered":"
VMOD processing want to before\/after VCL function processing. But, I do not want to write extra line. How to d […]<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24,3],"tags":[33,34],"class_list":["post-1046","post","type-post","status-publish","format-standard","hentry","category-english","category-3","tag-varnish3-0-2","tag-vmod","category-24-id","category-3-id","post-seq-1","post-parity-odd","meta-position-corners","fix"],"_links":{"self":[{"href":"https:\/\/blog.xcir.net\/index.php?rest_route=\/wp\/v2\/posts\/1046","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.xcir.net\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.xcir.net\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.xcir.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.xcir.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1046"}],"version-history":[{"count":32,"href":"https:\/\/blog.xcir.net\/index.php?rest_route=\/wp\/v2\/posts\/1046\/revisions"}],"predecessor-version":[{"id":1234,"href":"https:\/\/blog.xcir.net\/index.php?rest_route=\/wp\/v2\/posts\/1046\/revisions\/1234"}],"wp:attachment":[{"href":"https:\/\/blog.xcir.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1046"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.xcir.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1046"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.xcir.net\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1046"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}