X-Git-Url: http://www.lcore.org/git/lcore.git/blobdiff_plain/4782a5c5afee47721cc617daa40dd29828342c2b..d8d568ba2b45905cbe2c8e1956b6444d5b6560f4:/dnscore.pas

diff --git a/dnscore.pas b/dnscore.pas
index bb4fab4..600581d 100755
--- a/dnscore.pas
+++ b/dnscore.pas
@@ -54,25 +54,33 @@
 }
 unit dnscore;
 
-
-
 {$ifdef fpc}{$mode delphi}{$endif}
 
-
-
-
+{$include lcoreconfig.inc}
 
 interface
 
 uses binipstuff,classes,pgtypes;
 
 var usewindns : boolean = {$ifdef win32}true{$else}false{$endif};
-//hint to users of this unit that they should use windows dns instead.
-//May be disabled by applications if desired. (e.g. if setting a custom
-//dnsserverlist).
+{hint to users of this unit that they should use windows dns instead.
+May be disabled by applications if desired. (e.g. if setting a custom
+dnsserverlist).
 
-//note: this unit will not be able to self populate it's dns server list on
-//older versions of windows.
+note: this unit will not be able to self populate it's dns server list on
+older versions of windows.}
+
+const
+  useaf_default=0;
+  useaf_preferv4=1;
+  useaf_preferv6=2;
+  useaf_v4=3;
+  useaf_v6=4;
+{
+hint to users of this unit to how to deal with connecting to hostnames regarding ipv4 or ipv6 usage
+can be set by apps as desired
+}
+var useaf:integer = useaf_default;
 
 const
   maxnamelength=127;
@@ -115,6 +123,7 @@ type
     parsepacket:boolean;
     resultstr:string;
     resultbin:tbinip;
+    resultlist:tbiniplist;
     resultaction:integer;
     numrr1:array[0..3] of integer;
     numrr2:integer;
@@ -147,13 +156,14 @@ type
 //if you must but please document them at the same time --plugwash
 
 //function buildrequest(const name:string;var packet:tdnspacket;requesttype:word):integer;
-//function makereversename(const binip:tbinip):string;
+
+//returns the DNS name used to reverse look up an IP, such as 4.3.2.1.in-addr.arpa for 1.2.3.4
+function makereversename(const binip:tbinip):string;
 
 procedure setstate_request_init(const name:string;var state:tdnsstate);
 
 //set up state for a foward lookup. A family value of AF_INET6 will give only
-//ipv6 results. Any other value will give ipv4 results in preference and ipv6
-//results if ipv4 results are not available;
+//ipv6 results. Any other value will give only ipv4 results
 procedure setstate_forward(const name:string;var state:tdnsstate;family:integer);
 
 procedure setstate_reverse(const binip:tbinip;var state:tdnsstate);
@@ -177,14 +187,27 @@ var
   dnsserverlist : tstringlist;
 //  currentdnsserverno : integer;
 
+
+//getcurrentsystemnameserver returns the nameserver the app should use and sets
+//id to the id of that nameserver. id should later be used to report how laggy
+//the servers response was and if it was timed out.
 function getcurrentsystemnameserver(var id:integer) :string;
+procedure reportlag(id:integer;lag:integer); //lag should be in microseconds and should be -1 to report a timeout
 
 //var
 //  unixnameservercache:string;
 { $endif}
 
 
-procedure reportlag(id:integer;lag:integer); //lag should be in microseconds and should be -1 to report a timeout
+{$ifdef linux}{$ifdef ipv6}
+function getv6localips:tbiniplist;
+procedure initpreferredmode;
+
+var
+  preferredmodeinited:boolean;
+
+{$endif}{$endif}
+
 var
   failurereason:string;
 
@@ -337,25 +360,37 @@ end;
 
 {==============================================================================}
 
-procedure setstate_return(const rrp:trrpointer;len:integer;var state:tdnsstate);
-var
-  a:integer;
+function getipfromrr(const rrp:trrpointer;len:integer):tbinip;
 begin
-  state.resultaction := action_done;
-  state.resultstr := '';
+  fillchar(result,sizeof(result),0);
   case trr(rrp.p^).requesttype of
     querytype_a: begin
       if htons(trr(rrp.p^).datalen) <> 4 then exit;
-      move(trr(rrp.p^).data,state.resultbin.ip,4);
-      state.resultbin.family :=AF_INET;
+      move(trr(rrp.p^).data,result.ip,4);
+      result.family :=AF_INET;
     end;
     {$ifdef ipv6}
     querytype_aaaa: begin
       if htons(trr(rrp.p^).datalen) <> 16 then exit;
-      state.resultbin.family := AF_INET6;
-      move(trr(rrp.p^).data,state.resultbin.ip6,16);
+      result.family := AF_INET6;
+      move(trr(rrp.p^).data,result.ip6,16);
     end;
     {$endif}
+  else
+    {}
+  end;
+end;
+
+procedure setstate_return(const rrp:trrpointer;len:integer;var state:tdnsstate);
+var
+  a:integer;
+begin
+  state.resultaction := action_done;
+  state.resultstr := '';
+  case trr(rrp.p^).requesttype of
+    querytype_a{$ifdef ipv6},querytype_aaaa{$endif}: begin
+      state.resultbin := getipfromrr(rrp,len);
+    end;
   else
     {other reply types (PTR, MX) return a hostname}
     state.resultstr := decodename(state.recvpacket,state.recvpacketlen,taddrint(rrp.p)-taddrint(@state.recvpacket)+10,0,a);
@@ -456,6 +491,19 @@ begin
       goto failure;
     end;
 
+    {if we requested A or AAAA build a list of all replies}
+    if (state.requesttype = querytype_a) or (state.requesttype = querytype_aaaa) then begin
+      state.resultlist := biniplist_new;
+      for a := state.numrr1[0] to (state.numrr1[0]+state.numrr1[1]-1) do begin
+        rrptemp := @state.rrdata[1+a*sizeof(trrpointer)];
+        rrtemp := rrptemp.p;
+        b := rrptemp.len;
+        if rrtemp.requesttype = state.requesttype then begin
+          biniplist_add(state.resultlist,getipfromrr(rrptemp^,b));
+        end;
+      end;
+    end;
+
     {- check for items of the requested type in answer section, if so return success first}
     for a := state.numrr1[0] to (state.numrr1[0]+state.numrr1[1]-1) do begin
       rrptemp := @state.rrdata[1+a*sizeof(trrpointer)];
@@ -480,23 +528,7 @@ begin
 
     {no cnames found, no items of correct type found}
     if state.forwardfamily <> 0 then goto failure;
-{$ifdef ipv6}
-    if (state.requesttype = querytype_a) then begin
-      {v6 only: in case of forward, look for AAAA in alternative section}
-      for a := state.numrr1[0]+state.numrr1[1]+state.numrr1[2] to (state.numrr2-1) do begin
-        rrptemp := @state.rrdata[1+a*sizeof(trrpointer)];
-        rrtemp := rrptemp.p;
-        b := rrptemp.len;
-        if rrtemp.requesttype = querytype_aaaa then begin
-          setstate_return(rrptemp^,b,state);
-          exit;
-        end;
-      end;
-      {no AAAA's found in alternative, do a recursive lookup for them}
-      state.requesttype := querytype_aaaa;
-      goto recursed;
-    end;
-{$endif}
+
     goto failure;
 recursed:
     {here it needs recursed lookup}
@@ -587,6 +619,7 @@ begin
   {$ifdef win32}
     if iphlpapi=0 then iphlpapi := loadlibrary('iphlpapi.dll');
     if not assigned(getnetworkparams) then @getnetworkparams := getprocaddress(iphlpapi,'GetNetworkParams');
+    if not assigned(getnetworkparams) then exit;
     fixed_info_len := 0;
     if GetNetworkParams(nil,@fixed_info_len)<>ERROR_BUFFER_OVERFLOW then exit;
     //fixed_info_len :=sizeof(tfixed_info);
@@ -635,7 +668,7 @@ begin
 end;
 
 function getcurrentsystemnameserver(var id:integer):string;
-var 
+var
   counter : integer;
 
 begin
@@ -666,6 +699,65 @@ begin
 
 end;
 
+
+
+{$ifdef linux}{$ifdef ipv6}
+function getv6localips:tbiniplist;
+var
+  t:textfile;
+  s,s2:string;
+  ip:tbinip;
+  a:integer;
+begin
+  result := biniplist_new;
+
+  assignfile(t,'/proc/net/if_inet6');
+  {$i-}reset(t);{$i+}
+  if ioresult <> 0 then exit; {none found, return empty list}
+
+  while not eof(t) do begin
+    readln(t,s);
+    s2 := '';
+    for a := 0 to 7 do begin
+      if (s2 <> '') then s2 := s2 + ':';
+      s2 := s2 + copy(s,(a shl 2)+1,4);
+    end;
+    ipstrtobin(s2,ip);
+    if ip.family <> 0 then biniplist_add(result,ip);
+  end;
+  closefile(t);
+end;
+
+procedure initpreferredmode;
+var
+  l:tbiniplist;
+  a:integer;
+  ip:tbinip;
+  ipmask_global,ipmask_6to4,ipmask_teredo:tbinip;
+
+begin
+  if preferredmodeinited then exit;
+  if useaf <> useaf_default then exit;
+  useaf := useaf_preferv4;
+  l := getv6localips;
+  ipstrtobin('2000::',ipmask_global);
+  ipstrtobin('2001::',ipmask_teredo);
+  ipstrtobin('2002::',ipmask_6to4);
+  {if there is any v6 IP which is globally routable and not 6to4 and not teredo, prefer v6}
+  for a := biniplist_getcount(l)-1 downto 0 do begin
+    ip := biniplist_get(l,a);
+    if not comparebinipmask(ip,ipmask_global,3) then continue;
+    if comparebinipmask(ip,ipmask_teredo,32) then continue;
+    if comparebinipmask(ip,ipmask_6to4,16) then continue;
+    useaf := useaf_preferv6;
+    preferredmodeinited := true;
+    exit;
+  end;
+end;
+
+{$endif}{$endif}
+
+
 {  quick and dirty description of dns packet structure to aid writing and
    understanding of parser code, refer to appropriate RFCs for proper specs
 - all words are network order