V6 backports (#1986)

Backporting commits:

* 8b31858 :  Portability: remove explicit check for libdl
* dd3292c : Refactor peerRefreshDNS() to clarify its (void*)1 logic
* 0ef767a: Nil request dereference in
           ACLExtUser and SourceDomainCheck ACLs

configure.ac

@@ -393,14 +393,6 @@ AS_IF([test "x$squid_opt_aufs_threads" != "x"],[
     [Defines how many threads aufs uses for I/O])
 ])
 
-## TODO check if this is necessary, LT_INIT does these checks
-SQUID_AUTO_LIB(dl,[dynamic linking],[LIBDL])
-AS_IF([test "x$with_dl" != "xno"],[
-  CXXFLAGS="$LIBDL_CFLAGS $CXXFLAGS"
-  LDFLAGS="$LIBDL_PATH $LDFLAGS"
-  AC_CHECK_LIB(dl, dlopen)
-])
-
 AC_DEFUN([LIBATOMIC_CHECKER],[
   AC_MSG_CHECKING(whether linking $1 -latomic works)
   AC_LINK_IFELSE([

src/acl/ExtUser.h

@@ -27,6 +27,7 @@ class ACLExtUser : public ACL
     char const *typeString() const override;
     void parse() override;
     int match(ACLChecklist *checklist) override;
+    bool requiresRequest() const override { return true; }
     SBufList dump() const override;
     bool empty () const override;
 

src/acl/SourceDomain.cc

@@ -36,7 +36,11 @@ SourceDomainLookup::LookupDone(const char *, const Dns::LookupDetails &details,
 {
     ACLFilledChecklist *checklist = Filled((ACLChecklist*)data);
     checklist->markSourceDomainChecked();
-    checklist->request->recordLookup(details);
+    if (checklist->request)
+        checklist->request->recordLookup(details);
+    else
+        debugs(28, 3, "no request to recordLookup()");
+
     checklist->resumeNonBlockingCheck(SourceDomainLookup::Instance());
 }
 

src/neighbors.cc

@@ -57,7 +57,8 @@ static void neighborAlive(CachePeer *, const MemObject *, const icp_common_t *);
 static void neighborAliveHtcp(CachePeer *, const MemObject *, const HtcpReplyData *);
 #endif
 static void neighborCountIgnored(CachePeer *);
-static void peerRefreshDNS(void *);
+static void peerDnsRefreshCheck(void *);
+static void peerDnsRefreshStart();
 static IPH peerDNSConfigure;
 static void peerProbeConnect(CachePeer *, const bool reprobeIfBusy = false);
 static CNCB peerProbeConnectDone;
@@ -583,7 +584,7 @@ neighbors_init(void)
         }
     }
 
-    peerRefreshDNS((void *) 1);
+    peerDnsRefreshStart();
 
     sep = getservbyname("echo", "udp");
     echo_port = sep ? ntohs((unsigned short) sep->s_port) : 7;
@@ -1237,24 +1238,32 @@ peerDNSConfigure(const ipcache_addrs *ia, const Dns::LookupDetails &, void *data
 }
 
 static void
-peerRefreshDNS(void *data)
+peerScheduleDnsRefreshCheck(const double delayInSeconds)
 {
-    CachePeer *p = nullptr;
-
-    if (eventFind(peerRefreshDNS, nullptr))
-        eventDelete(peerRefreshDNS, nullptr);
+    if (eventFind(peerDnsRefreshCheck, nullptr))
+        eventDelete(peerDnsRefreshCheck, nullptr);
+    eventAddIsh("peerDnsRefreshCheck", peerDnsRefreshCheck, nullptr, delayInSeconds, 1);
+}
 
-    if (!data && 0 == stat5minClientRequests()) {
+static void
+peerDnsRefreshCheck(void *)
+{
+    if (!stat5minClientRequests()) {
         /* no recent client traffic, wait a bit */
-        eventAddIsh("peerRefreshDNS", peerRefreshDNS, nullptr, 180.0, 1);
+        peerScheduleDnsRefreshCheck(180.0);
         return;
     }
 
-    for (p = Config.peers; p; p = p->next)
+    peerDnsRefreshStart();
+}
+
+static void
+peerDnsRefreshStart()
+{
+    for (auto p = Config.peers; p; p = p->next)
         ipcache_nbgethostbyname(p->host, peerDNSConfigure, p);
 
-    /* Reconfigure the peers every hour */
-    eventAddIsh("peerRefreshDNS", peerRefreshDNS, nullptr, 3600.0, 1);
+    peerScheduleDnsRefreshCheck(3600.0);
 }
 
 /// whether new TCP probes are currently banned