Monero addres from DNS TXT record implemented, tests pass

Still need to deal with DNSSEC and optional fields in the TXT record.

4 files changed, 102 insertions, 24 deletions

diff --git a/src/common/dns_utils.cpp b/src/common/dns_utils.cpp
index e3be79371..2ad98ca27 100644
--- a/src/common/dns_utils.cpp
+++ b/src/common/dns_utils.cpp
@@ -34,6 +34,22 @@
 namespace tools
 {
 
+// custom smart pointer.
+// TODO: see if std::auto_ptr and the like support custom destructors
+class ub_result_ptr
+{
+public:
+  ub_result_ptr()
+  {
+    ptr = nullptr;
+  }
+  ~ub_result_ptr()
+  {
+    ub_resolve_free(ptr);
+  }
+  ub_result* ptr;
+};
+
 struct DNSResolverData
 {
   ub_ctx* m_ub_context;
@@ -63,20 +79,22 @@ DNSResolver::~DNSResolver()
 
 std::vector<std::string> DNSResolver::get_ipv4(const std::string& url)
 {
-  ub_result* result = NULL;
+  // destructor takes care of cleanup
+  ub_result_ptr result;
+
   std::vector<std::string> retval;
 
   // call DNS resolver, blocking.  if return value not zero, something went wrong
-  if (!ub_resolve(m_data->m_ub_context, url.c_str(), LDNS_RR_TYPE_A, LDNS_RR_CLASS_IN, &result))
+  if (!ub_resolve(m_data->m_ub_context, url.c_str(), LDNS_RR_TYPE_A, LDNS_RR_CLASS_IN, &(result.ptr)))
   {
-    if (result->havedata)
+    if (result.ptr->havedata)
     {
-      for (int i=0; result->data[i] != NULL; i++)
+      for (int i=0; result.ptr->data[i] != NULL; i++)
       {
         char as_str[INET_ADDRSTRLEN];
 
         // convert bytes to string, append if no error
-        if (inet_ntop(AF_INET, result->data[i], as_str, sizeof(as_str)))
+        if (inet_ntop(AF_INET, result.ptr->data[i], as_str, sizeof(as_str)))
         {
           retval.push_back(as_str);
         }
@@ -84,27 +102,25 @@ std::vector<std::string> DNSResolver::get_ipv4(const std::string& url)
     }
   }
 
-  // cleanup
-  ub_resolve_free(result);
   return retval;
 }
 
 std::vector<std::string> DNSResolver::get_ipv6(const std::string& url)
 {
-  ub_result* result = NULL;
+  ub_result_ptr result;
   std::vector<std::string> retval;
 
   // call DNS resolver, blocking.  if return value not zero, something went wrong
-  if (!ub_resolve(m_data->m_ub_context, url.c_str(), LDNS_RR_TYPE_AAAA, LDNS_RR_CLASS_IN, &result))
+  if (!ub_resolve(m_data->m_ub_context, url.c_str(), LDNS_RR_TYPE_AAAA, LDNS_RR_CLASS_IN, &(result.ptr)))
   {
-    if (result->havedata)
+    if (result.ptr->havedata)
     {
-      for (int i=0; result->data[i] != NULL; i++)
+      for (int i=0; result.ptr->data[i] != NULL; i++)
       {
         char as_str[INET6_ADDRSTRLEN];
 
         // convert bytes to string, append if no error
-        if (inet_ntop(AF_INET6, result->data[i], as_str, sizeof(as_str)))
+        if (inet_ntop(AF_INET6, result.ptr->data[i], as_str, sizeof(as_str)))
         {
           retval.push_back(as_str);
         }
@@ -112,15 +128,22 @@ std::vector<std::string> DNSResolver::get_ipv6(const std::string& url)
     }
   }
 
-  // cleanup
-  ub_resolve_free(result);
   return retval;
 }
 
-std::string DNSResolver::get_payment_address(const std::string& url)
+std::string DNSResolver::get_txt_record(const std::string& url)
 {
-  std::string retval;
-  return retval;
+  ub_result_ptr result;
+
+  // call DNS resolver, blocking.  if return value not zero, something went wrong
+  if (!ub_resolve(m_data->m_ub_context, url.c_str(), LDNS_RR_TYPE_TXT, LDNS_RR_CLASS_IN, &(result.ptr)))
+  {
+    if (result.ptr->havedata)
+    {
+      return std::string(result.ptr->data[0]);
+    }
+  }
+  return std::string();
 }
 
 DNSResolver& DNSResolver::instance()
diff --git a/src/common/dns_utils.h b/src/common/dns_utils.h
index 6697d8fff..ff54c1e07 100644
--- a/src/common/dns_utils.h
+++ b/src/common/dns_utils.h
@@ -82,17 +82,15 @@ public:
    std::vector<std::string> get_ipv6(const std::string& url);
 
   /**
-   * @brief gets a monero address from the TXT record of the DNS query response
-   *
-   * returns a monero address string from the TXT record associated with URL
-   * if no TXT record present, or no valid monero address in TXT,
-   * returns an empty string.
+   * @brief gets a TXT record from a DNS query for the supplied URL;
+   * if no TXT record present returns an empty string.
    *
    * @param url A string containing a URL to query for
    *
-   * @return 
+   * @return A string containing a TXT record; or an empty string
    */
-  std::string get_payment_address(const std::string& url);
+  // TODO: modify this to accomodate DNSSEC
+  std::string get_txt_record(const std::string& url);
 
   /**
    * @brief Gets the singleton instance of DNSResolver
diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index 9ba6f245a..adc9c1f61 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -47,6 +47,7 @@ using namespace epee;
 #include "serialization/binary_utils.h"
 #include "cryptonote_protocol/blobdatatype.h"
 #include "crypto/electrum-words.h"
+#include "common/dns_utils.h"
 
 extern "C"
 {
@@ -751,6 +752,7 @@ void wallet2::add_unconfirmed_tx(const cryptonote::transaction& tx, uint64_t cha
   utd.m_sent_time = time(NULL);
   utd.m_tx = tx;
 }
+
 //----------------------------------------------------------------------------------------------------
 void wallet2::transfer(const std::vector<cryptonote::tx_destination_entry>& dsts, size_t fake_outputs_count,
                        uint64_t unlock_time, uint64_t fee, const std::vector<uint8_t>& extra, cryptonote::transaction& tx, pending_tx& ptx)
@@ -815,6 +817,58 @@ std::vector<std::vector<cryptonote::tx_destination_entry>> split_amounts(
 }
 } // anonymous namespace
 
+/**
+ * @brief gets a monero address from the TXT record of a DNS entry
+ *
+ * gets the monero address from the TXT record of the DNS entry associated
+ * with <url>.  If this lookup fails, or the TXT record does not contain an
+ * XMR address in the correct format, returns an empty string.  <dnssec_valid>
+ * will be set true or false according to whether or not the DNS query passes
+ * DNSSEC validation.
+ *
+ * @param url the url to look up
+ * @param dnssec_valid return-by-reference for DNSSEC status of query
+ *
+ * @return a monero address (as a string) or an empty string
+ */
+std::string wallet2::address_from_url(const std::string& url, bool& dnssec_valid)
+{
+  // TODO: update this correctly once DNSResolver::get_txt_record() supports it.
+  dnssec_valid = false;
+  // get txt record
+  std::string txt = tools::DNSResolver::instance().get_txt_record(url);
+
+  if (txt.size())
+  {
+    return address_from_txt_record(txt);
+  }
+  return std::string();
+}
+
+//----------------------------------------------------------------------------------------------------
+std::string wallet2::address_from_txt_record(const std::string& s)
+{
+  // make sure the txt record has "oa1:xmr" and find it
+  auto pos = s.find("oa1:xmr");
+
+  // search from there to find "recipient_address="
+  pos = s.find("recipient_address=", pos);
+
+  pos += 18; // move past "recipient_address="
+
+  // find the next semicolon
+  auto pos2 = s.find(";", pos);
+  if (pos2 != std::string::npos)
+  {
+    // length of address == 95, we can at least validate that much here
+    if (pos2 - pos == 95)
+    {
+      return s.substr(pos, 95);
+    }
+  }
+  return std::string();
+}
+
 //----------------------------------------------------------------------------------------------------
 // take a pending tx and actually send it to the daemon
 void wallet2::commit_tx(pending_tx& ptx)
diff --git a/src/wallet/wallet2.h b/src/wallet/wallet2.h
index 3311e3438..6e6d7cafb 100644
--- a/src/wallet/wallet2.h
+++ b/src/wallet/wallet2.h
@@ -196,6 +196,9 @@ namespace tools
 
     static bool parse_payment_id(const std::string& payment_id_str, crypto::hash& payment_id);
 
+    static std::string address_from_url(const std::string& url, bool& dnssec_valid);
+
+    static std::string address_from_txt_record(const std::string& s);
   private:
     bool store_keys(const std::string& keys_file_name, const std::string& password);
     void load_keys(const std::string& keys_file_name, const std::string& password);