Merge pull request #394

3c10239 unbound: use the mini event fallback implementation (moneromooo-monero)
4e138a0 dns_utils: remove unnecessary string conversion (moneromooo-monero)
f928468 dns_utils: factor the fetching code for different DNS record types (moneromooo-monero)
4ef0da1 dns_utils: simplify string handling and fix leak (moneromooo-monero)
ae5f28c dns_utils: add a const where possible (moneromooo-monero)
f43d465 dns_utils: lock access to the singleton (moneromooo-monero)
5990344 dns: make ctor private (moneromooo-monero)

2 files changed, 56 insertions, 70 deletions

diff --git a/src/common/dns_utils.cpp b/src/common/dns_utils.cpp
index e442d3d81..5cb5ed2de 100644
--- a/src/common/dns_utils.cpp
+++ b/src/common/dns_utils.cpp
@@ -38,6 +38,8 @@
 using namespace epee;
 namespace bf = boost::filesystem;
 
+static std::mutex instance_lock;
+
 namespace
 {
 
@@ -98,8 +100,10 @@ namespace tools
 {
 
 // fuck it, I'm tired of dealing with getnameinfo()/inet_ntop/etc
-std::string ipv4_to_string(const char* src)
+std::string ipv4_to_string(const char* src, size_t len)
 {
+  assert(memchr(src, 0, len));
+
   std::stringstream ss;
   unsigned int bytes[4];
   for (int i = 0; i < 4; i++)
@@ -116,8 +120,10 @@ std::string ipv4_to_string(const char* src)
 
 // this obviously will need to change, but is here to reflect the above
 // stop-gap measure and to make the tests pass at least...
-std::string ipv6_to_string(const char* src)
+std::string ipv6_to_string(const char* src, size_t len)
 {
+  assert(memchr(src, 0, len));
+
   std::stringstream ss;
   unsigned int bytes[8];
   for (int i = 0; i < 8; i++)
@@ -136,6 +142,11 @@ std::string ipv6_to_string(const char* src)
   return ss.str();
 }
 
+std::string txt_to_string(const char* src, size_t len)
+{
+  return std::string(src+1, len-1);
+}
+
 // custom smart pointer.
 // TODO: see if std::auto_ptr and the like support custom destructors
 template<typename type, void (*freefunc)(type*)>
@@ -164,8 +175,6 @@ private:
 };
 
 typedef class scoped_ptr<ub_result,ub_resolve_free> ub_result_ptr;
-static void freestring(char *ptr) { free(ptr); }
-typedef class scoped_ptr<char,freestring> string_ptr;
 
 struct DNSResolverData
 {
@@ -213,14 +222,13 @@ DNSResolver::~DNSResolver()
   }
 }
 
-std::vector<std::string> DNSResolver::get_ipv4(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
+std::vector<std::string> DNSResolver::get_record(const std::string& url, int record_type, std::string (*reader)(const char *,size_t), bool& dnssec_available, bool& dnssec_valid)
 {
   std::vector<std::string> addresses;
   dnssec_available = false;
   dnssec_valid = false;
 
-  string_ptr urlC(strdup(url.c_str()));
-  if (!check_address_syntax(urlC))
+  if (!check_address_syntax(url.c_str()))
   {
     return addresses;
   }
@@ -229,7 +237,7 @@ std::vector<std::string> DNSResolver::get_ipv4(const std::string& url, bool& dns
   ub_result_ptr result;
 
   // call DNS resolver, blocking.  if return value not zero, something went wrong
-  if (!ub_resolve(m_data->m_ub_context, urlC, DNS_TYPE_A, DNS_CLASS_IN, &result))
+  if (!ub_resolve(m_data->m_ub_context, url.c_str(), record_type, DNS_CLASS_IN, &result))
   {
     dnssec_available = (result->secure || (!result->secure && result->bogus));
     dnssec_valid = result->secure && !result->bogus;
@@ -237,7 +245,7 @@ std::vector<std::string> DNSResolver::get_ipv4(const std::string& url, bool& dns
     {
       for (size_t i=0; result->data[i] != NULL; i++)
       {
-        addresses.push_back(ipv4_to_string(result->data[i]));
+        addresses.push_back((*reader)(result->data[i], result->len[i]));
       }
     }
   }
@@ -245,70 +253,19 @@ std::vector<std::string> DNSResolver::get_ipv4(const std::string& url, bool& dns
   return addresses;
 }
 
-std::vector<std::string> DNSResolver::get_ipv6(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
+std::vector<std::string> DNSResolver::get_ipv4(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
 {
-  std::vector<std::string> addresses;
-  dnssec_available = false;
-  dnssec_valid = false;
-
-  string_ptr urlC(strdup(url.c_str()));
-  if (!check_address_syntax(urlC))
-  {
-    return addresses;
-  }
-
-  ub_result_ptr result;
-
-  // call DNS resolver, blocking.  if return value not zero, something went wrong
-  if (!ub_resolve(m_data->m_ub_context, urlC, DNS_TYPE_AAAA, DNS_CLASS_IN, &result))
-  {
-    dnssec_available = (result->secure || (!result->secure && result->bogus));
-    dnssec_valid = result->secure && !result->bogus;
-    if (result->havedata)
-    {
-      for (size_t i=0; result->data[i] != NULL; i++)
-      {
-        addresses.push_back(ipv6_to_string(result->data[i]));
-      }
-    }
-  }
+  return get_record(url, DNS_TYPE_A, ipv4_to_string, dnssec_available, dnssec_valid);
+}
 
-  return addresses;
+std::vector<std::string> DNSResolver::get_ipv6(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
+{
+  return get_record(url, DNS_TYPE_AAAA, ipv6_to_string, dnssec_available, dnssec_valid);
 }
 
 std::vector<std::string> DNSResolver::get_txt_record(const std::string& url, bool& dnssec_available, bool& dnssec_valid)
 {
-  std::vector<std::string> records;
-  dnssec_available = false;
-  dnssec_valid = false;
-
-  string_ptr urlC(strdup(url.c_str()));
-  if (!check_address_syntax(urlC))
-  {
-    return records;
-  }
-
-  ub_result_ptr result;
-
-  // call DNS resolver, blocking.  if return value not zero, something went wrong
-  if (!ub_resolve(m_data->m_ub_context, urlC, DNS_TYPE_TXT, DNS_CLASS_IN, &result))
-  {
-    dnssec_available = (result->secure || (!result->secure && result->bogus));
-    dnssec_valid = result->secure && !result->bogus;
-    if (result->havedata)
-    {
-      for (size_t i=0; result->data[i] != NULL; i++)
-      {
-      	// plz fix this, but this does NOT work and spills over into parts of memory it shouldn't: records.push_back(result.ptr->data[i]);
-        char *restxt;
-        restxt = (char*) calloc(result->len[i]+1, 1);
-        memcpy(restxt, result->data[i]+1, result->len[i]-1);
-        records.push_back(restxt);
-      }
-    }
-  }
-
-  return records;
+  return get_record(url, DNS_TYPE_TXT, txt_to_string, dnssec_available, dnssec_valid);
 }
 
 std::string DNSResolver::get_dns_format_from_oa_address(const std::string& oa_addr)
@@ -326,6 +283,8 @@ std::string DNSResolver::get_dns_format_from_oa_address(const std::string& oa_ad
 
 DNSResolver& DNSResolver::instance()
 {
+  std::lock_guard<std::mutex> lock(instance_lock);
+
   static DNSResolver* staticInstance = NULL;
   if (staticInstance == NULL)
   {
@@ -334,7 +293,12 @@ DNSResolver& DNSResolver::instance()
   return *staticInstance;
 }
 
-bool DNSResolver::check_address_syntax(const char *addr)
+DNSResolver DNSResolver::create()
+{
+  return DNSResolver();
+}
+
+bool DNSResolver::check_address_syntax(const char *addr) const
 {
   // if string doesn't contain a dot, we won't consider it a url for now.
   if (strchr(addr,'.') == NULL)
diff --git a/src/common/dns_utils.h b/src/common/dns_utils.h
index 1e726c80c..63bf25445 100644
--- a/src/common/dns_utils.h
+++ b/src/common/dns_utils.h
@@ -49,7 +49,7 @@ struct DNSResolverData;
  */
 class DNSResolver
 {
-public:
+private:
 
   /**
    * @brief Constructs an instance of DNSResolver
@@ -58,6 +58,8 @@ public:
    */
   DNSResolver();
 
+public:
+
   /**
    * @brief takes care of freeing C pointers and such
    */
@@ -119,16 +121,36 @@ public:
    */
   static DNSResolver& instance();
 
+  /**
+   * @brief Gets a new instance of DNSResolver
+   *
+   * @return returns a pointer to the new object
+   */
+  static DNSResolver create();
+
 private:
 
   /**
+   * @brief gets all records of a given type from a DNS query for the supplied URL;
+   * if no such record is present returns an empty vector.
+   *
+   * @param url A string containing a URL to query for
+   * @param record_type the record type to retrieve (DNS_TYPE_A, etc)
+   * @param reader a function that converts a record data to a string
+   *
+   * @return A vector of strings containing the requested record; or an empty vector
+   */
+  // TODO: modify this to accomodate DNSSEC
+  std::vector<std::string> get_record(const std::string& url, int record_type, std::string (*reader)(const char *,size_t), bool& dnssec_available, bool& dnssec_valid);
+
+  /**
    * @brief Checks a string to see if it looks like a URL
    *
    * @param addr the string to be checked
    *
    * @return true if it looks enough like a URL, false if not
    */
-  bool check_address_syntax(const char *addr);
+  bool check_address_syntax(const char *addr) const;
 
   DNSResolverData *m_data;
 }; // class DNSResolver