[jira] [Updated] (TS-3455) Marking the cache STALE in lookup-complete causes abort()

["Luca Bruno (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TS-3455?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Luca Bruno updated TS-3455:
---------------------------
    Summary: Marking the cache STALE in lookup-complete causes abort()  (was: Renaming Cache-Control in read-response and marking the cache STALE in lookup-complete causes abort())

> Marking the cache STALE in lookup-complete causes abort()
> ---------------------------------------------------------
>
>                 Key: TS-3455
>                 URL: https://issues.apache.org/jira/browse/TS-3455
>             Project: Traffic Server
>          Issue Type: Bug
>            Reporter: Luca Bruno
>
> I've written a simple test case plugin for demonstrating this problem, not sure if it's a problem on my side, but that would also mean that the regex invalidate plugin would also abort().
> What the plugin does: in LOOKUP_COMPLETE, if the cache status is FRESH then set it to STALE.
> To reproduce:
> 1) First cacheable request to ATS gets cached
> 2) Request again the same url, the plugin triggers and set the cache to STALE. Then ATS does abort().
> Plugin code:
> {noformat}
> #include <ts/ts.h>
> #include <ts/remap.h>
> #include <ts/experimental.h>
> #include <stdlib.h>
> #include <stdio.h>
> #include <getopt.h>
> #include <string.h>
> #include <string>
> #include <iterator>
> #include <map>
> const char PLUGIN_NAME[] = "maybebug";
> static int Handler(TSCont cont, TSEvent event, void *edata);
> struct PluginState {
>   PluginState()
>   {
>     cont = TSContCreate(Handler, NULL);
>     TSContDataSet(cont, this);
>   }
>   ~PluginState()
>   {
>     TSContDestroy(cont);
>   }
>   TSCont cont;
> };
> static int Handler(TSCont cont, TSEvent event, void* edata) {
>   TSHttpTxn txn = (TSHttpTxn)edata;
>   if (event == TS_EVENT_HTTP_CACHE_LOOKUP_COMPLETE) {
>     int lookup_status;
>     if (TS_SUCCESS == TSHttpTxnCacheLookupStatusGet(txn, &lookup_status)) {
>       TSDebug(PLUGIN_NAME, "lookup complete: %d", lookup_status);
>       if (lookup_status == TS_CACHE_LOOKUP_HIT_FRESH) {
>         TSDebug(PLUGIN_NAME, "set stale");
>         TSHttpTxnCacheLookupStatusSet(txn, TS_CACHE_LOOKUP_HIT_STALE);
>       }
>     }
>   }
>   TSHttpTxnReenable(txn, TS_EVENT_HTTP_CONTINUE);
>   return TS_EVENT_NONE;
> }
> void TSPluginInit (int argc, const char *argv[]) {
>   TSPluginRegistrationInfo info;
>   info.plugin_name = strdup("cappello");
>   info.vendor_name = strdup("foo");
>   info.support_email = strdup("foo@bar.com");
>   if (TSPluginRegister(TS_SDK_VERSION_3_0 , &info) != TS_SUCCESS) {
>     TSError("Plugin registration failed");
>   }
>   PluginState* state = new PluginState();
>   TSHttpHookAdd(TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK, state->cont);
> }
> {noformat}
> Output:
> {noformat}
> [Mar 19 18:40:36.254] Server {0x7f6df0b4f740} DIAG: (maybebug) lookup complete: 0
> [Mar 19 18:40:40.854] Server {0x7f6decfee700} DIAG: (maybebug) lookup complete: 2
> [Mar 19 18:40:40.854] Server {0x7f6decfee700} DIAG: (maybebug) set stale
> FATAL: HttpTransact.cc:433: failed assert `s->pending_work == NULL`
> traffic_server - STACK TRACE: 
> /usr/local/lib/libtsutil.so.5(ink_fatal+0xa3)[0x7f6df072186d]
> /usr/local/lib/libtsutil.so.5(_Z12ink_get_randv+0x0)[0x7f6df071f3a0]
> traffic_server[0x60d0aa]
> traffic_server(_ZN12HttpTransact22HandleCacheOpenReadHitEPNS_5StateE+0xf82)[0x619206]
> ...
> {noformat}
> What happens in gdb is that HandleCacheOpenReadHit is called twice in the same request. The first time s->pending_work is NULL, the second time it's not NULL.
> The patch below fixes the problem:
> {noformat}
> diff --git a/proxy/http/HttpTransact.cc b/proxy/http/HttpTransact.cc
> index 0078ef1..852f285 100644
> --- a/proxy/http/HttpTransact.cc
> +++ b/proxy/http/HttpTransact.cc
> @@ -2641,11 +2641,6 @@ HttpTransact::HandleCacheOpenReadHit(State* s)
>  //        ink_release_assert(s->current.request_to == PARENT_PROXY ||
>  //                    s->http_config_param->no_dns_forward_to_parent != 0);
>  
> -        // Set ourselves up to handle pending revalidate issues
> -        //  after the PP DNS lookup
> -        ink_assert(s->pending_work == NULL);
> -        s->pending_work = issue_revalidate;
> -
>          // We must be going a PARENT PROXY since so did
>          //  origin server DNS lookup right after state Start
>          //
> @@ -2654,6 +2649,11 @@ HttpTransact::HandleCacheOpenReadHit(State* s)
>          //  missing ip but we won't take down the system
>          //
>          if (s->current.request_to == PARENT_PROXY) {
> +          // Set ourselves up to handle pending revalidate issues
> +          //  after the PP DNS lookup
> +          ink_assert(s->pending_work == NULL);
> +          s->pending_work = issue_revalidate;
> +
>            TRANSACT_RETURN(SM_ACTION_DNS_LOOKUP, PPDNSLookup);
>          } else if (s->current.request_to == ORIGIN_SERVER) {
>            TRANSACT_RETURN(SM_ACTION_DNS_LOOKUP, OSDNSLookup);
> {noformat}



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