handling allocate request

net/server/internal/sturn/attribute.go

@@ -1,6 +1,9 @@
 package sturn
 
 import (
+  "crypto/md5"
+  "crypto/hmac"
+  "crypto/sha1"
   "errors"
   "strings"
   "strconv"
@@ -167,8 +170,35 @@ func writeAttribute(attribute *SturnAttribute, buf []byte, pos int) (error, int)
     buf[pos + 6] = 0x04
     buf[pos + 7] = 0x01
     return nil, 8
+  } else if attribute.atrType == ATRMessageIntegrity {
+    buf[pos + 1], buf[pos + 0] = setAttributeType(ATRMessageIntegrity);
+    buf[pos + 2] = 0;
+    buf[pos + 3] = 0x14;
+    key := md5.Sum([]byte("user:databag.dweb:pass"));
+
+    // set hash size
+    lengthField0 := buf[2]
+    lengthField1 := buf[3]
+    hashLength := pos + 4
+    buf[2] = byte((hashLength >> 8) % 256);
+    buf[3] = byte(hashLength % 256);
+    hash := getHmac(key[:], buf[0:pos]);
+    buf[2] = lengthField0
+    buf[3] = lengthField1
+
+    for i := 0; i < 20; i++ {
+      buf[4 + pos + i] = hash[i];
+    }
+
+    return nil, 24
   } else {
     fmt.Println("UNKNOWN!");
   }
   return nil, 8
 }
+
+func getHmac(key []byte, data []byte) []byte {
+  mac := hmac.New(sha1.New, key)
+	mac.Write(data)
+	return mac.Sum(nil)
+}

net/server/internal/sturn/message.go

@@ -145,7 +145,7 @@ func (s *Sturn) sendAllocateError(msg *SturnMessage, addr net.Addr) {
   })
   attributes = append(attributes, SturnAttribute{
     atrType: ATRRealm,
-    strValue: "databag",
+    strValue: "databag.dweb",
   })
   response := &SturnMessage{
     class: CLSError,
@@ -169,14 +169,52 @@ func (s *Sturn) handleAllocateRequest(msg *SturnMessage, addr net.Addr) {
     return;
   }
 
-  port, err := s.getRelayPort();
+  relayPort, err := s.getRelayPort();
   if err != nil {
     fmt.Println(err);
     s.sendAllocateError(msg, addr)
     return
   }
 
-  fmt.Println("ALLOCATE REQUEST", msg, port);
+  address := strings.Split(addr.String(), ":")
+  ip := address[0];
+  port, _ := strconv.Atoi(address[1]);
+  //port := 53046
+  var attributes []SturnAttribute
+  attributes = append(attributes, SturnAttribute{
+    atrType: ATRXorRelayedAddress,
+    byteValue: FAMIPv4,
+    intValue: int32(relayPort),
+//    strValue: "98.234.232.221",
+    strValue: "192.168.13.233",
+  });
+  attributes = append(attributes, SturnAttribute{
+    atrType: ATRLifetime,
+    intValue: int32(600),
+  });
+  attributes = append(attributes, SturnAttribute{
+    atrType: ATRXorMappedAddress,
+    byteValue: FAMIPv4,
+    intValue: int32(port),
+    strValue: ip,
+  });
+  attributes = append(attributes, SturnAttribute{
+    atrType: ATRMessageIntegrity,
+  });
+  response := &SturnMessage{
+    class: CLSResponse,
+    method: MEHAllocate,
+    transaction: msg.transaction,
+    attributes: attributes,
+  };
+
+  err, n := writeMessage(response, s.buf);
+
+  if err != nil {
+    fmt.Printf("failed to write stun response");
+  } else {
+    (*s.conn).WriteTo(s.buf[:n], addr);
+  }
   return
 }