dnsdist: Refactoring to merge the UDP and TCP paths

pdns/dnscrypt.hh

@@ -24,11 +24,24 @@
 
 #ifndef HAVE_DNSCRYPT
 
+/* let's just define a few types and values so that the rest of
+   the code can ignore whether DNSCrypt support is available */
+#define DNSCRYPT_MAX_RESPONSE_PADDING_AND_MAC_SIZE (0)
+
+class DNSCryptContext
+{
+};
+
 class DNSCryptQuery
 {
+  DNSCryptQuery(const std::shared_ptr<DNSCryptContext>& ctx): d_ctx(ctx)
+  {
+  }
+private:
+  std::shared_ptr<DNSCryptContext> d_ctx{nullptr};
 };
 
-#else
+#else /* HAVE_DNSCRYPT */
 
 #include <memory>
 #include <string>

pdns/dnsdist-ecs.cc

@@ -464,9 +464,7 @@ static int removeEDNSOptionFromOptions(unsigned char* optionsStart, const uint16
 
 int removeEDNSOptionFromOPT(char* optStart, size_t* optLen, const uint16_t optionCodeToRemove)
 {
-  /* we need at least:
-     root label (1), type (2), class (2), ttl (4) + rdlen (2)*/
-  if (*optLen < 11) {
+  if (*optLen < optRecordMinimumSize) {
     return EINVAL;
   }
   const unsigned char* end = (const unsigned char*) optStart + *optLen;
@@ -490,15 +488,13 @@ int removeEDNSOptionFromOPT(char* optStart, size_t* optLen, const uint16_t optio
 
 bool isEDNSOptionInOpt(const std::string& packet, const size_t optStart, const size_t optLen, const uint16_t optionCodeToFind, size_t* optContentStart, uint16_t* optContentLen)
 {
-  /* we need at least:
-   root label (1), type (2), class (2), ttl (4) + rdlen (2)*/
-  if (optLen < 11) {
+  if (optLen < optRecordMinimumSize) {
     return false;
   }
   size_t p = optStart + 9;
   uint16_t rdLen = (0x100*packet.at(p) + packet.at(p+1));
   p += sizeof(rdLen);
-  if (rdLen > (optLen - 11)) {
+  if (rdLen > (optLen - optRecordMinimumSize)) {
     return false;
   }
 
@@ -741,3 +737,31 @@ bool queryHasEDNS(const DNSQuestion& dq)
 
   return false;
 }
+
+bool getEDNS0Record(const DNSQuestion& dq, EDNS0Record& edns0)
+{
+  uint16_t optStart;
+  size_t optLen = 0;
+  bool last = false;
+  const char * packet = reinterpret_cast<const char*>(dq.dh);
+  std::string packetStr(packet, dq.len);
+  int res = locateEDNSOptRR(packetStr, &optStart, &optLen, &last);
+  if (res != 0) {
+    // no EDNS OPT RR
+    return false;
+  }
+
+  if (optLen < optRecordMinimumSize) {
+    return false;
+  }
+
+  if (optStart < dq.len && packetStr.at(optStart) != 0) {
+    // OPT RR Name != '.'
+    return false;
+  }
+
+  static_assert(sizeof(EDNS0Record) == sizeof(uint32_t), "sizeof(EDNS0Record) must match sizeof(uint32_t) AKA RR TTL size");
+  // copy out 4-byte "ttl" (really the EDNS0 record), after root label (1) + type (2) + class (2).
+  memcpy(&edns0, packet + optStart + 5, sizeof edns0);
+  return true;
+}

pdns/dnsdist-ecs.hh

@@ -21,6 +21,9 @@
  */
 #pragma once
 
+// root label (1), type (2), class (2), ttl (4) + rdlen (2)
+static const size_t optRecordMinimumSize = 11;
+
 extern size_t g_EdnsUDPPayloadSize;
 extern uint16_t g_PayloadSizeSelfGenAnswers;
 
@@ -42,3 +45,4 @@ bool parseEDNSOptions(DNSQuestion& dq);
 
 int getEDNSZ(const DNSQuestion& dq);
 bool queryHasEDNS(const DNSQuestion& dq);
+bool getEDNS0Record(const DNSQuestion& dq, EDNS0Record& edns0);