Merge pull request #1523

d81cb087 Added (not yet enabled) HTTP client authentication (Lee Clagett)

6 files changed, 790 insertions, 189 deletions

diff --git a/contrib/epee/include/net/http_auth.h b/contrib/epee/include/net/http_auth.h
index 795d213d9..bdbfa7524 100644
--- a/contrib/epee/include/net/http_auth.h
+++ b/contrib/epee/include/net/http_auth.h
@@ -28,32 +28,35 @@
 #pragma once
 
 #include <boost/optional/optional.hpp>
+#include <boost/utility/string_ref.hpp>
 #include <cstdint>
-#include "http_base.h"
+#include <functional>
 #include <string>
 #include <utility>
 
+#include "http_base.h"
+
 namespace epee
 {
 namespace net_utils
 {
   namespace http
   {
-    //! Implements RFC 2617 digest auth. Digests from RFC 7616 can be added.
-    class http_auth
+    struct login
     {
-    public:
-      struct login
-      {
-        login() : username(), password() {}
-        login(std::string username_, std::string password_)
-          : username(std::move(username_)), password(std::move(password_))
-        {}
+      login() : username(), password() {}
+      login(std::string username_, std::string password_)
+        : username(std::move(username_)), password(std::move(password_))
+      {}
 
-        std::string username;
-        std::string password;
-      };
+      std::string username;
+      std::string password;
+    };
 
+    //! Implements RFC 2617 digest auth. Digests from RFC 7616 can be added.
+    class http_server_auth
+    {
+    public:
       struct session
       {
         session(login credentials_)
@@ -65,21 +68,97 @@ namespace net_utils
         std::uint32_t counter;
       };
 
-      http_auth() : user() {}
-      http_auth(login credentials);
+      http_server_auth() : user() {}
+      http_server_auth(login credentials);
 
       //! \return Auth response, or `boost::none` iff `request` had valid auth.
       boost::optional<http_response_info> get_response(const http_request_info& request)
       {
         if (user)
+          return do_get_response(request);
+        return boost::none;
+      }
+    private:
+      boost::optional<http_response_info> do_get_response(const http_request_info& request);
+
+      boost::optional<session> user;
+    };
+
+    //! Implements RFC 2617 digest auth. Digests from RFC 7616 can be added.
+    class http_client_auth
+    {
+    public:
+      enum status : std::uint8_t { kSuccess = 0, kBadPassword, kParseFailure };
+
+      struct session
+      {
+        session(login credentials_)
+          : credentials(std::move(credentials_)), server(), counter(0)
+        {}
+
+        struct keys
         {
-          return process(request);
-        }
+          using algorithm =
+            std::function<std::string(const session&, boost::string_ref, boost::string_ref)>;
+
+          keys() : nonce(), opaque(), realm(), generator() {}
+          keys(std::string nonce_, std::string opaque_, std::string realm_, algorithm generator_)
+            : nonce(std::move(nonce_))
+            , opaque(std::move(opaque_))
+            , realm(std::move(realm_))
+            , generator(std::move(generator_))
+          {}
+
+          std::string nonce;
+          std::string opaque;
+          std::string realm;
+          algorithm generator;
+        };
+
+        login credentials;
+        keys server;
+        std::uint32_t counter;
+      };
+
+      http_client_auth() : user() {}
+      http_client_auth(login credentials);
+
+      /*!
+        Clients receiving a 401 response code from the server should call this
+        function to process the server auth. Then, before every client request,
+        `get_auth_field()` should be called to retrieve the newest
+        authorization request.
+
+        \return `kBadPassword` if client will never be able to authenticate,
+          `kParseFailure` if all server authentication responses were invalid,
+          and `kSuccess` if `get_auth_field` is ready to generate authorization
+          fields.
+      */
+      status handle_401(const http_response_info& response)
+      {
+        if (user)
+          return do_handle_401(response);
+        return kBadPassword;
+      }
+
+      /*!
+        After calling `handle_401`, clients should call this function to
+        generate an authentication field for every request.
+
+        \return A HTTP "Authorization" field if `handle_401(...)` previously
+          returned `kSuccess`.
+      */
+      boost::optional<std::pair<std::string, std::string>> get_auth_field(
+        const boost::string_ref method, const boost::string_ref uri)
+      {
+        if (user)
+          return do_get_auth_field(method, uri);
         return boost::none;
       }
 
     private:
-      boost::optional<http_response_info> process(const http_request_info& request);
+      status do_handle_401(const http_response_info&);
+      boost::optional<std::pair<std::string, std::string>> do_get_auth_field(boost::string_ref, boost::string_ref);
 
       boost::optional<session> user;
     };
diff --git a/contrib/epee/include/net/http_protocol_handler.h b/contrib/epee/include/net/http_protocol_handler.h
index 3813f9d7c..69ea04fbe 100644
--- a/contrib/epee/include/net/http_protocol_handler.h
+++ b/contrib/epee/include/net/http_protocol_handler.h
@@ -52,7 +52,7 @@ namespace net_utils
 		{
 			std::string m_folder;
 			std::string m_required_user_agent;
-			boost::optional<http_auth::login> m_user;
+			boost::optional<login> m_user;
 			critical_section m_lock;
 		};
 
@@ -173,7 +173,7 @@ namespace net_utils
 				: simple_http_connection_handler<t_connection_context>(psnd_hndlr, config),
 					m_config(config),
 					m_conn_context(conn_context),
-					m_auth(m_config.m_user ? http_auth{*m_config.m_user} : http_auth{})
+					m_auth(m_config.m_user ? http_server_auth{*m_config.m_user} : http_server_auth{})
 			{}
 			inline bool handle_request(const http_request_info& query_info, http_response_info& response)
 			{
@@ -214,7 +214,7 @@ namespace net_utils
 			//simple_http_connection_handler::config_type m_stub_config;
 			config_type& m_config;
 			t_connection_context& m_conn_context;
-			http_auth m_auth;
+			http_server_auth m_auth;
 		};
 	}
 }
diff --git a/contrib/epee/include/net/http_server_impl_base.h b/contrib/epee/include/net/http_server_impl_base.h
index f6b2d6941..a5cc1a917 100644
--- a/contrib/epee/include/net/http_server_impl_base.h
+++ b/contrib/epee/include/net/http_server_impl_base.h
@@ -53,7 +53,7 @@ namespace epee
     {}
 
     bool init(const std::string& bind_port = "0", const std::string& bind_ip = "0.0.0.0",
-      std::string user_agent = "", boost::optional<net_utils::http::http_auth::login> user = boost::none)
+      std::string user_agent = "", boost::optional<net_utils::http::login> user = boost::none)
     {
 
       //set self as callback handler
diff --git a/contrib/epee/src/http_auth.cpp b/contrib/epee/src/http_auth.cpp
index 98870a7a9..7fd32dabc 100644
--- a/contrib/epee/src/http_auth.cpp
+++ b/contrib/epee/src/http_auth.cpp
@@ -28,34 +28,41 @@
 #include "net/http_auth.h"
 
 #include <array>
+#include <boost/algorithm/string/find_iterator.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/fusion/adapted/std_tuple.hpp>
 #include <boost/fusion/algorithm/iteration/for_each.hpp>
+#include <boost/fusion/algorithm/iteration/iter_fold.hpp>
 #include <boost/fusion/algorithm/query/any.hpp>
+#include <boost/fusion/iterator/distance.hpp>
+#include <boost/fusion/iterator/value_of.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
+#include <boost/fusion/sequence/intrinsic/size.hpp>
 #include <boost/range/algorithm/copy.hpp>
 #include <boost/range/algorithm/find_if.hpp>
 #include <boost/range/iterator_range_core.hpp>
 #include <boost/range/join.hpp>
+#include <boost/spirit/include/karma_generate.hpp>
+#include <boost/spirit/include/karma_uint.hpp>
 #include <boost/spirit/include/qi_alternative.hpp>
 #include <boost/spirit/include/qi_and_predicate.hpp>
 #include <boost/spirit/include/qi_char.hpp>
 #include <boost/spirit/include/qi_char_class.hpp>
 #include <boost/spirit/include/qi_difference.hpp>
 #include <boost/spirit/include/qi_kleene.hpp>
-#include <boost/spirit/include/qi_optional.hpp>
 #include <boost/spirit/include/qi_parse.hpp>
 #include <boost/spirit/include/qi_plus.hpp>
 #include <boost/spirit/include/qi_no_case.hpp>
+#include <boost/spirit/include/qi_not_predicate.hpp>
 #include <boost/spirit/include/qi_raw.hpp>
 #include <boost/spirit/include/qi_rule.hpp>
 #include <boost/spirit/include/qi_sequence.hpp>
 #include <boost/spirit/include/qi_string.hpp>
 #include <boost/spirit/include/qi_symbols.hpp>
 #include <boost/spirit/include/qi_uint.hpp>
-#include <boost/utility/string_ref.hpp>
 #include <cassert>
-#include <functional>
 #include <iterator>
+#include <limits>
 #include <tuple>
 #include <type_traits>
 
@@ -75,6 +82,8 @@ characters without "consuming" the input character. */
 
 namespace
 {
+  namespace http = epee::net_utils::http;
+
   // string_ref is only constexpr if length is given
   template<std::size_t N>
   constexpr boost::string_ref ceref(const char (&arg)[N])
@@ -82,12 +91,17 @@ namespace
     return boost::string_ref(arg, N - 1);
   }
 
-  constexpr const auto auth_realm = ceref(u8"monero-wallet-rpc");
+  constexpr const auto client_auth_field = ceref(u8"Authorization");
+  constexpr const auto server_auth_field = ceref(u8"WWW-authenticate");
+  constexpr const auto auth_realm = ceref(u8"monero-rpc");
   constexpr const char comma = 44;
   constexpr const char equal_sign = 61;
   constexpr const char quote = 34;
+  constexpr const char zero = 48;
   constexpr const auto sess_algo = ceref(u8"-sess");
 
+  constexpr const unsigned client_reserve_size = 512; //!< std::string::reserve size for clients
+
   //// Digest Algorithms
 
   template<std::size_t N>
@@ -147,15 +161,15 @@ namespace
   };
   constexpr const boost::string_ref md5_::name;
 
-  //! Digest Algorithms available for HTTP Digest Auth.
+  //! Digest Algorithms available for HTTP Digest Auth. Sort better algos to the left
   constexpr const std::tuple<md5_> digest_algorithms{};
 
-  //// Various String Parsing Utilities
+  //// Various String Utilities
 
   struct ascii_tolower_
   {
     template<typename Char>
-    Char operator()(Char value) const noexcept
+    constexpr Char operator()(Char value) const noexcept
     {
       static_assert(std::is_integral<Char>::value, "only integral types supported");
       return (65 <= value && value <= 90) ? (value + 32) : value;
@@ -166,34 +180,243 @@ namespace
   struct ascii_iequal_
   {
     template<typename Char>
-    bool operator()(Char left, Char right) const noexcept
+    constexpr bool operator()(Char left, Char right) const noexcept
     {
       return ascii_tolower(left) == ascii_tolower(right);
     }
   };
   constexpr const ascii_iequal_ ascii_iequal{};
 
+  struct http_list_separator_
+  {
+    template<typename Char>
+    bool operator()(Char value) const noexcept
+    {
+      static_assert(std::is_integral<Char>::value, "only integral types supported");
+      return boost::spirit::char_encoding::ascii::isascii_(value) &&
+        (value == comma || boost::spirit::char_encoding::ascii::isspace(value));
+    }
+  };
+  constexpr const http_list_separator_ http_list_separator{};
+
+  std::string to_string(boost::iterator_range<const char*> source)
+  {
+    return {source.begin(), source.size()};
+  }
+
+  template<typename T>
+  void add_first_field(std::string& str, const char* const name, const T& value)
+  {
+    str.append(name);
+    str.push_back(equal_sign);
+    boost::copy(value, std::back_inserter(str));
+  }
+
+  template<typename T>
+  void add_field(std::string& str, const char* const name, const T& value)
+  {
+    str.push_back(comma);
+    add_first_field(str, name, value);
+  }
+
+  template<typename T>
+  using quoted_result = boost::joined_range<
+    const boost::joined_range<const boost::string_ref, const T>, const boost::string_ref
+  >;
+
+  template<typename T>
+  quoted_result<T> quoted(const T& arg)
+  {
+    return boost::range::join(boost::range::join(ceref(u8"\""), arg), ceref(u8"\""));
+  }
+
   //// Digest Authentication
-  
-  struct auth_request
+
+  template<typename Digest>
+  typename std::result_of<Digest()>::type generate_a1(
+    Digest digest, const http::login& creds, const boost::string_ref realm)
+  {
+    return digest(creds.username, u8":", realm, u8":", creds.password);
+  }
+
+  template<typename Digest>
+  typename std::result_of<Digest()>::type generate_a1(
+    Digest digest, const http::http_client_auth::session& user)
+  {
+    return generate_a1(std::move(digest), user.credentials, user.server.realm);
+  }
+
+  template<typename T>
+  void init_client_value(std::string& str,
+    const boost::string_ref algorithm, const http::http_client_auth::session& user,
+    const boost::string_ref uri, const T& response)
+  {
+    str.append(u8"Digest ");
+    add_first_field(str, u8"algorithm", algorithm);
+    add_field(str, u8"nonce", quoted(user.server.nonce));
+    add_field(str, u8"realm", quoted(user.server.realm));
+    add_field(str, u8"response", quoted(response));
+    add_field(str, u8"uri", quoted(uri));
+    add_field(str, u8"username", quoted(user.credentials.username));
+    if (!user.server.opaque.empty())
+      add_field(str, u8"opaque", quoted(user.server.opaque));
+  }
+
+  //! Implements superseded algorithm specified in RFC 2069
+  template<typename Digest>
+  struct old_algorithm
+  {
+    explicit old_algorithm(Digest digest_) : digest(std::move(digest_)) {}
+
+    std::string operator()(const http::http_client_auth::session& user,
+      const boost::string_ref method, const boost::string_ref uri) const
+    {
+      const auto response = digest(
+        generate_a1(digest, user), u8":", user.server.nonce, u8":", digest(method, u8":", uri)
+      );
+      std::string out{};
+      out.reserve(client_reserve_size);
+      init_client_value(out, Digest::name, user, uri, response);
+      return out;
+    }
+  private:
+    Digest digest;
+  };
+
+  //! Implements the `qop=auth` algorithm specified in RFC 2617
+  template<typename Digest>
+  struct auth_algorithm
+  {
+    explicit auth_algorithm(Digest digest_) : digest(std::move(digest_)) {}
+
+    std::string operator()(const http::http_client_auth::session& user,
+      const boost::string_ref method, const boost::string_ref uri) const
+    {
+      namespace karma = boost::spirit::karma;
+      using counter_type = decltype(user.counter);
+      static_assert(
+        std::numeric_limits<counter_type>::radix == 2, "unexpected radix for counter"
+      );
+      static_assert(
+        std::numeric_limits<counter_type>::digits <= 32,
+        "number of digits will cause underflow on padding below"
+      );
+
+      std::string out{};
+      out.reserve(client_reserve_size);
+
+      karma::generate(std::back_inserter(out), karma::hex(user.counter));
+      out.insert(out.begin(), 8 - out.size(), zero); // zero left pad
+      if (out.size() != 8)
+        return {};
+
+      std::array<char, 8> nc{{}};
+      boost::copy(out, nc.data());
+      const auto response = digest(
+        generate_a1(digest, user), u8":", user.server.nonce, u8":", nc, u8"::auth:", digest(method, u8":", uri)
+      );
+      out.clear();
+      init_client_value(out, Digest::name, user, uri, response);
+      add_field(out, u8"qop", ceref(u8"auth"));
+      add_field(out, u8"nc", nc);
+      return out;
+    }
+
+  private:
+    Digest digest;
+  };
+
+  //! Processes client "Authorization" and server "WWW-authenticate" HTTP fields
+  struct auth_message
   {
     using iterator = const char*;
     enum status{ kFail = 0, kStale, kPass };
 
-    static status verify(const std::string& method, const std::string& request,
-      const epee::net_utils::http::http_auth::session& user)
+    //! \return Status of the `response` field from the client
+    static status verify(const boost::string_ref method, const boost::string_ref request,
+      const http::http_server_auth::session& user)
+    {
+      const auto parsed = parse(request);
+      if (parsed &&
+          boost::equals(parsed->username, user.credentials.username) &&
+          boost::fusion::any(digest_algorithms, has_valid_response{*parsed, user, method}))
+      {
+        if (boost::equals(parsed->nonce, user.nonce))
+        {
+          // RFC 2069 format does not verify nc value - allow just once
+          if (user.counter == 1 || (!parsed->qop.empty() && parsed->counter() == user.counter))
+          {
+            return kPass;
+          }
+        }
+        return kStale;
+      }
+      return kFail;
+    }
+
+    //! \return Information needed to generate client authentication `response`s.
+    static http::http_client_auth::session::keys extract(
+      const http::http_response_info& response, const bool is_first)
+    {
+      using field = std::pair<std::string, std::string>;
+
+      server_parameters best{};
+
+      const std::list<field>& fields = response.m_additional_fields;
+      auto current = fields.begin();
+      const auto end = fields.end();
+      while (true)
+      {
+        current = std::find_if(current, end, [] (const field& value) {
+          return boost::equals(server_auth_field, value.first, ascii_iequal);
+        });
+        if (current == end)
+          break;
+
+        const auto parsed = parse(current->second);
+        if (parsed)
+        {
+          server_parameters local_best = parsed->algorithm.empty() ?
+            server_parameters{*parsed, boost::fusion::find<md5_>(digest_algorithms)} :
+            boost::fusion::iter_fold(digest_algorithms, server_parameters{}, matches_algorithm{*parsed});
+
+          if (local_best.index < best.index)
+            best = std::move(local_best);
+        }
+        ++current;
+      }
+      if (is_first || boost::equals(best.stale, ceref(u8"true"), ascii_iequal))
+        return best.take();
+      return {}; // authentication failed with bad user/pass
+    }
+
+  private:
+    explicit auth_message()
+      : algorithm()
+      , cnonce()
+      , nc()
+      , nonce()
+      , qop()
+      , realm()
+      , response()
+      , stale()
+      , uri()
+      , username() {
+    }
+
+    static boost::optional<auth_message> parse(const boost::string_ref request)
     {
       struct parser
       {
-        using field_parser = std::function<bool(const parser&, iterator&, iterator, auth_request&)>;
+        using field_parser = std::function<bool(const parser&, iterator&, iterator, auth_message&)>;
 
-        explicit parser() : field_table(), skip_whitespace(), header(), token(), fields() {
+        explicit parser() : field_table(), skip_whitespace(), header(), quoted_string(), token(), fields() {
           using namespace std::placeholders;
           namespace qi = boost::spirit::qi;
 
           struct parse_nc
           {
-            bool operator()(const parser&, iterator& current, const iterator end, auth_request& result) const
+            bool operator()(const parser&, iterator& current, const iterator end, auth_message& result) const
             {
               return qi::parse(
                 current, end,
@@ -212,19 +435,19 @@ namespace
           };
           struct parse_string
           {
-            bool operator()(const parser&, iterator& current, const iterator end,
+            bool operator()(const parser& parse, iterator& current, const iterator end,
               boost::iterator_range<iterator>& result) const
             {
-              return qi::parse(
-                current, end,
-                (qi::lit(quote) >> qi::raw[+(u8"\\\"" | (qi::ascii::char_ - quote))] >> qi::lit(quote)),
-                result
-              );
+              return qi::parse(current, end, parse.quoted_string, result);
+            }
+            bool operator()(const parser& parse, iterator& current, const iterator end) const
+            {
+              return qi::parse(current, end, parse.quoted_string);
             }
           };
           struct parse_response
           {
-            bool operator()(const parser&, iterator& current, const iterator end, auth_request& result) const
+            bool operator()(const parser&, iterator& current, const iterator end, auth_message& result) const
             {
               using byte = qi::uint_parser<std::uint8_t, 16, 2, 2>;
               return qi::parse(
@@ -236,38 +459,41 @@ namespace
           };
 
           field_table.add
-            (u8"algorithm", std::bind(parse_token{}, _1, _2, _3, std::bind(&auth_request::algorithm, _4)))
-            (u8"cnonce", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_request::cnonce, _4)))
+            (u8"algorithm", std::bind(parse_token{}, _1, _2, _3, std::bind(&auth_message::algorithm, _4)))
+            (u8"cnonce", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_message::cnonce, _4)))
+            (u8"domain", std::bind(parse_string{}, _1, _2, _3)) // ignore field
             (u8"nc", parse_nc{})
-            (u8"nonce", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_request::nonce, _4)))
-            (u8"qop", std::bind(parse_token{}, _1, _2, _3, std::bind(&auth_request::qop, _4)))
-            (u8"realm", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_request::realm, _4)))
+            (u8"nonce", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_message::nonce, _4)))
+            (u8"opaque", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_message::opaque, _4)))
+            (u8"qop", std::bind(parse_token{}, _1, _2, _3, std::bind(&auth_message::qop, _4)))
+            (u8"realm", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_message::realm, _4)))
             (u8"response", parse_response{})
-            (u8"uri", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_request::uri, _4)))
-            (u8"username", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_request::username, _4)));
+            (u8"stale", std::bind(parse_token{}, _1, _2, _3, std::bind(&auth_message::stale, _4)))
+            (u8"uri", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_message::uri, _4)))
+            (u8"username", std::bind(parse_string{}, _1, _2, _3, std::bind(&auth_message::username, _4)));
 
           skip_whitespace = *(&qi::ascii::char_ >> qi::ascii::space);
           header = skip_whitespace >> qi::ascii::no_case[u8"digest"] >> skip_whitespace;
+          quoted_string = (qi::lit(quote) >> qi::raw[+(u8"\\\"" | (qi::ascii::char_ - quote))] >> qi::lit(quote));
           token =
-            -qi::lit(quote) >>
-            qi::raw[+(&qi::ascii::char_ >> (qi::ascii::graph - qi::ascii::char_(u8"()<>@,;:\\\"/[]?={}")))] >>
-            -qi::lit(quote);
+            (!qi::lit(quote) >> qi::raw[+(&qi::ascii::char_ >> (qi::ascii::graph - qi::ascii::char_(u8"()<>@,;:\\\"/[]?={}")))]) |
+            quoted_string;
           fields = field_table >> skip_whitespace >> equal_sign >> skip_whitespace;
         }
 
-        boost::optional<auth_request> operator()(const std::string& method, const std::string& request) const
+        boost::optional<auth_message> operator()(const boost::string_ref request) const
         { 
           namespace qi = boost::spirit::qi;
            
-          iterator current = request.data();
-          const iterator end = current + request.size();
+          iterator current = request.begin();
+          const iterator end = request.end();
 
           if (!qi::parse(current, end, header))
           {
             return boost::none;
           }
 
-          auth_request info(method);
+          auth_message info{};
           field_parser null_parser{};
           std::reference_wrapper<const field_parser> field = null_parser;
 
@@ -288,26 +514,13 @@ namespace
         > field_table;
         boost::spirit::qi::rule<iterator> skip_whitespace;
         boost::spirit::qi::rule<iterator> header;
+        boost::spirit::qi::rule<iterator, boost::iterator_range<iterator>()> quoted_string;
         boost::spirit::qi::rule<iterator, boost::iterator_range<iterator>()> token;
         boost::spirit::qi::rule<iterator, std::reference_wrapper<const field_parser>()> fields;
       }; // parser
 
-      static const parser parse;
-      return do_verify(parse(method, request), user);
-    }
-
-  private:
-    explicit auth_request(const std::string& method_)
-      : algorithm()
-      , cnonce()
-      , method(method_)
-      , nc()
-      , nonce()
-      , qop()
-      , realm()
-      , response()
-      , uri()
-      , username() {
+      static const parser parse_;
+      return parse_(request);
     }
 
     struct has_valid_response
@@ -326,12 +539,6 @@ namespace
         );
       }
 
-      template<typename Digest>
-      typename std::result_of<Digest()>::type generate_auth(Digest digest) const
-      {
-        return digest(request.method, u8":", request.uri);
-      }
-
       template<typename Result>
       bool check(const Result& result) const
       {
@@ -344,96 +551,130 @@ namespace
         if (boost::starts_with(request.algorithm, Digest::name, ascii_iequal) ||
             (request.algorithm.empty() && std::is_same<md5_, Digest>::value))
         {
-          auto key = digest(user.credentials.username, u8":", auth_realm, u8":", user.credentials.password);
-
+          auto key = generate_a1(digest, user.credentials, auth_realm);
           if (boost::ends_with(request.algorithm, sess_algo, ascii_iequal))
           {
             key = digest(key, u8":", request.nonce, u8":", request.cnonce);
           }
 
+          auto auth = digest(method, u8":", request.uri);
           if (request.qop.empty())
           {
-            return check(generate_old_response(digest, std::move(key), generate_auth(digest)));
+            return check(generate_old_response(std::move(digest), std::move(key), std::move(auth)));
           }
           else if (boost::equals(ceref(u8"auth"), request.qop, ascii_iequal))
           {
-            return check(generate_new_response(digest, std::move(key), generate_auth(digest)));
+            return check(generate_new_response(std::move(digest), std::move(key), std::move(auth)));
           }
         }
         return false;
       }
 
-      const auth_request& request;
-      const epee::net_utils::http::http_auth::session& user;
+      const auth_message& request;
+      const http::http_server_auth::session& user;
+      const boost::string_ref method;
     };
 
-    static status do_verify(const boost::optional<auth_request>& request,
-      const epee::net_utils::http::http_auth::session& user)
+    boost::optional<std::uint32_t> counter() const
+    {
+      namespace qi = boost::spirit::qi;
+      using hex = qi::uint_parser<std::uint32_t, 16>;
+      std::uint32_t value = 0;
+      const bool converted = qi::parse(nc.begin(), nc.end(), hex{}, value);
+      return boost::make_optional(converted, value);
+    }
+
+    struct server_parameters
     {
-      if (request && 
-          boost::equals(request->username, user.credentials.username) &&
-          boost::fusion::any(digest_algorithms, has_valid_response{*request, user}))
+      server_parameters()
+        : nonce(), opaque(), realm(), stale(), value_generator()
+        , index(boost::fusion::size(digest_algorithms))
+      {}
+
+      template<typename DigestIter>
+      explicit server_parameters(const auth_message& request, const DigestIter& digest)
+        : nonce(request.nonce)
+        , opaque(request.opaque)
+        , stale(request.stale)
+        , realm(request.realm)
+        , value_generator()
+        , index(boost::fusion::distance(boost::fusion::begin(digest_algorithms), digest))
       {
-        if (boost::equals(request->nonce, user.nonce))
+        using digest_type = typename boost::fusion::result_of::value_of<DigestIter>::type;
+
+        // debug check internal state of the auth_message class
+        assert(
+          (std::is_same<digest_type, md5_>::value) ||
+          boost::equals((*digest).name, request.algorithm, ascii_iequal)
+        );
+        if (request.qop.empty())
+          value_generator = old_algorithm<digest_type>{*digest};
+        else
         {
-          // RFC 2069 format does not verify nc value - allow just once
-          if (user.counter == 1 || (!request->qop.empty() && request->counter() == user.counter))
+          for (auto elem = boost::make_split_iterator(request.qop, boost::token_finder(http_list_separator));
+               !elem.eof();
+               ++elem)
           {
-            return kPass;
+            if (boost::equals(ceref(u8"auth"), *elem, ascii_iequal))
+            {
+              value_generator = auth_algorithm<digest_type>{*digest};
+              break;
+            }
           }
+          if (!value_generator) // no supported qop mode
+            index = boost::fusion::size(digest_algorithms);
         }
-        return kStale;
       }
-      return kFail;
-    }
 
-    boost::optional<std::uint32_t> counter() const
+      http::http_client_auth::session::keys take()
+      {
+        return {to_string(nonce), to_string(opaque), to_string(realm), std::move(value_generator)};
+      }
+
+      boost::iterator_range<iterator> nonce;
+      boost::iterator_range<iterator> opaque;
+      boost::iterator_range<iterator> realm;
+      boost::iterator_range<iterator> stale;
+      http::http_client_auth::session::keys::algorithm value_generator;
+      unsigned index;
+    };
+
+    struct matches_algorithm
     {
-      namespace qi = boost::spirit::qi;
-      using hex = qi::uint_parser<std::uint32_t, 16>;
-      std::uint32_t value = 0;
-      const bool converted = qi::parse(nc.begin(), nc.end(), hex{}, value);
-      return boost::make_optional(converted, value);
-    }
+      template<typename DigestIter>
+      server_parameters operator()(server_parameters current, const DigestIter& digest) const
+      {
+        if (!current.value_generator)
+        {
+          if (boost::equals(response.algorithm, (*digest).name, ascii_iequal))
+          {
+            current = server_parameters{response, digest};
+          }
+        }
+        return current;
+      }
+      const auth_message& response;
+    };
+
 
     boost::iterator_range<iterator> algorithm;
     boost::iterator_range<iterator> cnonce;
-    boost::string_ref method;
     boost::iterator_range<iterator> nc;
     boost::iterator_range<iterator> nonce;
+    boost::iterator_range<iterator> opaque;
     boost::iterator_range<iterator> qop;
     boost::iterator_range<iterator> realm;
     boost::iterator_range<iterator> response;
+    boost::iterator_range<iterator> stale;
     boost::iterator_range<iterator> uri;
     boost::iterator_range<iterator> username; 
-  }; // auth_request
+  }; // auth_message
 
   struct add_challenge
   {
-    template<typename T>
-    static void add_field(std::string& str, const char* const name, const T& value)
-    {
-      str.push_back(comma);
-      str.append(name);
-      str.push_back(equal_sign);
-      boost::range::copy(value, std::back_inserter(str));
-    }
-
-    template<typename T>
-    using quoted_result = boost::joined_range<
-      const boost::joined_range<const boost::string_ref, const T>, const boost::string_ref
-    >;
-
-    template<typename T>
-    static quoted_result<T> quoted(const T& arg)
-    {
-      return boost::range::join(boost::range::join(ceref(u8"\""), arg), ceref(u8"\""));
-    }
-
     template<typename Digest>
     void operator()(const Digest& digest) const
     {
-      static constexpr const auto fname = ceref(u8"WWW-authenticate");
       static constexpr const auto fvalue = ceref(u8"Digest qop=\"auth\"");
 
       for (unsigned i = 0; i < 2; ++i)
@@ -448,17 +689,16 @@ namespace
         add_field(out, u8"nonce", quoted(nonce));
         add_field(out, u8"stale", is_stale ? ceref("true") : ceref("false"));
         
-        fields.push_back(std::make_pair(std::string(fname), std::move(out)));
+        fields.push_back(std::make_pair(std::string(server_auth_field), std::move(out)));
       }
     }
 
-    const std::string& nonce;
+    const boost::string_ref nonce;
     std::list<std::pair<std::string, std::string>>& fields;
     const bool is_stale;
   };
 
-  epee::net_utils::http::http_response_info create_digest_response(
-    const std::string& nonce, const bool is_stale)
+  http::http_response_info create_digest_response(const boost::string_ref nonce, const bool is_stale)
   {
     epee::net_utils::http::http_response_info rc{};
     rc.m_response_code = 401;
@@ -481,35 +721,35 @@ namespace epee
   {
     namespace http
     {
-      http_auth::http_auth(login credentials)
+      http_server_auth::http_server_auth(login credentials)
         : user(session{std::move(credentials)}) {
       }
 
-      boost::optional<http_response_info> http_auth::process(const http_request_info& request)
+      boost::optional<http_response_info> http_server_auth::do_get_response(const http_request_info& request)
       {
         assert(user);
         using field = std::pair<std::string, std::string>;
 
         const std::list<field>& fields = request.m_header_info.m_etc_fields;
         const auto auth = boost::find_if(fields, [] (const field& value) {
-          return boost::equals(ceref(u8"authorization"), value.first, ascii_iequal);
+          return boost::equals(client_auth_field, value.first, ascii_iequal);
         });
 
         bool is_stale = false;
         if (auth != fields.end())
         {
           ++(user->counter);
-          switch (auth_request::verify(request.m_http_method_str, auth->second, *user))
+          switch (auth_message::verify(request.m_http_method_str, auth->second, *user))
           {
-          case auth_request::kPass:
+          case auth_message::kPass:
             return boost::none;
 
-          case auth_request::kStale:
+          case auth_message::kStale:
             is_stale = true;
             break;
 
           default:
-          case auth_request::kFail:
+          case auth_message::kFail:
             break;
           }
         }
@@ -521,6 +761,35 @@ namespace epee
         }
         return create_digest_response(user->nonce, is_stale);
       }
+
+      http_client_auth::http_client_auth(login credentials)
+        : user(session{std::move(credentials)}) {
+      }
+
+      http_client_auth::status http_client_auth::do_handle_401(const http_response_info& response)
+      {
+        assert(user);
+        const bool first_auth = (user->counter == 0);
+        user->server = auth_message::extract(response, first_auth);
+        if (user->server.generator)
+        {
+          user->counter = 0;
+          return kSuccess;
+        }
+        return first_auth ? kParseFailure : kBadPassword;
+      }
+
+      boost::optional<std::pair<std::string, std::string>> http_client_auth::do_get_auth_field(
+        const boost::string_ref method, const boost::string_ref uri)
+      {
+        assert(user);
+        if (user->server.generator)
+        {
+          ++(user->counter);
+          return std::make_pair(std::string(client_auth_field), user->server.generator(*user, method, uri));
+        }
+        return boost::none;
+      }
     }
   }
 }
diff --git a/src/wallet/wallet_rpc_server.cpp b/src/wallet/wallet_rpc_server.cpp
index 21965c4c8..d61b11f8a 100644
--- a/src/wallet/wallet_rpc_server.cpp
+++ b/src/wallet/wallet_rpc_server.cpp
@@ -125,7 +125,7 @@ namespace tools
       }
     }
 
-    epee::net_utils::http::http_auth::login login{};
+    epee::net_utils::http::login login{};
 
     const bool disable_auth = command_line::get_arg(vm, arg_disable_rpc_login);
     const std::string user_pass = command_line::get_arg(vm, arg_rpc_login);
diff --git a/tests/unit_tests/http_auth.cpp b/tests/unit_tests/http_auth.cpp
index 7158850b6..97954642f 100644
--- a/tests/unit_tests/http_auth.cpp
+++ b/tests/unit_tests/http_auth.cpp
@@ -61,6 +61,7 @@
 #include "string_tools.h"
 
 namespace {
+namespace http = epee::net_utils::http;
 using fields = std::unordered_map<std::string, std::string>;
 using auth_responses = std::vector<fields>;
 
@@ -71,17 +72,28 @@ std::string quoted(std::string str)
   return str;
 }
 
-epee::net_utils::http::http_request_info make_request(const fields& args)
+void write_fields(std::string& out, const fields& args)
 {
   namespace karma = boost::spirit::karma;
-
-  std::string out{"   DIGEST   "};
   karma::generate(
     std::back_inserter(out),
     (karma::string << " = " << karma::string) % " , ", 
     args);
+}
+
+std::string write_fields(const fields& args)
+{
+  std::string out{};
+  write_fields(out, args);
+  return out;
+}
 
-  epee::net_utils::http::http_request_info request{};
+http::http_request_info make_request(const fields& args)
+{
+  std::string out{"   DIGEST   "};
+  write_fields(out, args);
+
+  http::http_request_info request{};
   request.m_http_method_str = "NOP";
   request.m_header_info.m_etc_fields.push_back(
     std::make_pair(u8"authorization", std::move(out))
@@ -89,6 +101,21 @@ epee::net_utils::http::http_request_info make_request(const fields& args)
   return request;
 }
 
+http::http_response_info make_response(const auth_responses& choices)
+{
+  http::http_response_info response{};
+  for (const auto& choice : choices)
+  {
+    std::string out{"   DIGEST   "};
+    write_fields(out, choice);
+
+    response.m_additional_fields.push_back(
+      std::make_pair(u8"WWW-authenticate", std::move(out))
+    );
+  }
+  return response;
+}
+
 bool has_same_fields(const auth_responses& in)
 {
   const std::vector<std::string> check{u8"nonce", u8"qop", u8"realm", u8"stale"};
@@ -113,7 +140,7 @@ bool has_same_fields(const auth_responses& in)
   return true;
 }
 
-bool is_unauthorized(const epee::net_utils::http::http_response_info& response)
+bool is_unauthorized(const http::http_response_info& response)
 {
   EXPECT_EQ(401, response.m_response_code);
   EXPECT_STREQ(u8"Unauthorized", response.m_response_comment.c_str());
@@ -123,39 +150,44 @@ bool is_unauthorized(const epee::net_utils::http::http_response_info& response)
     response.m_mime_tipe == u8"text/html";
 }
 
-
-auth_responses parse_response(const epee::net_utils::http::http_response_info& response)
+fields parse_fields(const std::string& value)
 {
   namespace qi = boost::spirit::qi;
 
+  fields out{};
+  const bool rc = qi::parse(
+    value.begin(), value.end(),
+    qi::lit(u8"Digest ") >> ((
+        +qi::ascii::alpha >>
+        qi::lit('=') >> (
+          (qi::lit('"') >> +(qi::ascii::char_ - '"') >> qi::lit('"')) |
+          +(qi::ascii::graph - qi::ascii::char_(u8"()<>@,;:\\\"/[]?={}"))
+        )
+      ) % ','
+    ) >> qi::eoi,
+    out
+  );
+  if (!rc)
+    throw std::runtime_error{"Bad field given in HTTP header"};
+
+  return out;
+}
+
+auth_responses parse_response(const http::http_response_info& response)
+{
   auth_responses result{};
 
   const auto end = response.m_additional_fields.end();
-  for (auto current = response.m_additional_fields.begin(); current != end; ++current)
+  for (auto current = response.m_additional_fields.begin();; ++current)
   {
     current = std::find_if(current, end, [] (const std::pair<std::string, std::string>& field) {
-        return boost::iequals(u8"www-authenticate", field.first);
+        return boost::equals(u8"WWW-authenticate", field.first);
     });
 
     if (current == end)
       return result;
 
-    std::unordered_map<std::string, std::string> fields{};
-    const bool rc = qi::parse(
-      current->second.begin(), current->second.end(),
-      qi::lit(u8"Digest ") >> ((
-          +qi::ascii::alpha >>
-          qi::lit('=') >> (
-            (qi::lit('"') >> +(qi::ascii::char_ - '"') >> qi::lit('"')) | 
-            +(qi::ascii::graph - qi::ascii::char_(u8"()<>@,;:\\\"/[]?={}"))
-          )
-        ) % ','
-      ) >> qi::eoi,
-      fields
-    );
-
-    if (rc)
-      result.push_back(std::move(fields));
+    result.push_back(parse_fields(current->second));
   }
   return result;
 }
@@ -175,15 +207,20 @@ std::string md5_hex(const std::string& in)
   return epee::string_tools::pod_to_hex(digest);
 }
 
-std::string get_a1(const epee::net_utils::http::http_auth::login& user, const auth_responses& responses)
+std::string get_a1(const http::login& user, const fields& src)
 {
-  const std::string& realm = responses.at(0).at(u8"realm");
+  const std::string& realm = src.at(u8"realm");
   return boost::join(
     std::vector<std::string>{user.username, realm, user.password}, u8":"
   );
 }
 
-std::string get_a1_sess(const epee::net_utils::http::http_auth::login& user, const std::string& cnonce, const auth_responses& responses)
+std::string get_a1(const http::login& user, const auth_responses& responses)
+{
+  return get_a1(user, responses.at(0));
+}
+
+std::string get_a1_sess(const http::login& user, const std::string& cnonce, const auth_responses& responses)
 {
   const std::string& nonce = responses.at(0).at(u8"nonce");
   return boost::join(
@@ -210,36 +247,36 @@ std::string get_nc(std::uint32_t count)
 }
 }
 
-TEST(HTTP_Auth, NotRequired)
+TEST(HTTP_Server_Auth, NotRequired)
 {
-  epee::net_utils::http::http_auth auth{};
-  EXPECT_FALSE(auth.get_response(epee::net_utils::http::http_request_info{}));
+  http::http_server_auth auth{};
+  EXPECT_FALSE(auth.get_response(http::http_request_info{}));
 }
 
-TEST(HTTP_Auth, MissingAuth)
+TEST(HTTP_Server_Auth, MissingAuth)
 {
-  epee::net_utils::http::http_auth auth{{"foo", "bar"}};
-  EXPECT_TRUE(bool(auth.get_response(epee::net_utils::http::http_request_info{})));
+  http::http_server_auth auth{{"foo", "bar"}};
+  EXPECT_TRUE(bool(auth.get_response(http::http_request_info{})));
   {
-    epee::net_utils::http::http_request_info request{};
+    http::http_request_info request{};
     request.m_header_info.m_etc_fields.push_back({"\xFF", "\xFF"});
     EXPECT_TRUE(bool(auth.get_response(request)));
   }
 }
 
-TEST(HTTP_Auth, BadSyntax)
+TEST(HTTP_Server_Auth, BadSyntax)
 {
-  epee::net_utils::http::http_auth auth{{"foo", "bar"}};
+  http::http_server_auth auth{{"foo", "bar"}};
   EXPECT_TRUE(bool(auth.get_response(make_request({{u8"algorithm", "fo\xFF"}}))));
   EXPECT_TRUE(bool(auth.get_response(make_request({{u8"cnonce", "\"000\xFF\""}}))));
   EXPECT_TRUE(bool(auth.get_response(make_request({{u8"cnonce \xFF =", "\"000\xFF\""}}))));
   EXPECT_TRUE(bool(auth.get_response(make_request({{u8" \xFF cnonce", "\"000\xFF\""}}))));
 }
 
-TEST(HTTP_Auth, MD5)
+TEST(HTTP_Server_Auth, MD5)
 {
-  epee::net_utils::http::http_auth::login user{"foo", "bar"};
-  epee::net_utils::http::http_auth auth{user};
+  http::login user{"foo", "bar"};
+  http::http_server_auth auth{user};
 
   const auto response = auth.get_response(make_request(fields{}));
   ASSERT_TRUE(bool(response));
@@ -283,12 +320,12 @@ TEST(HTTP_Auth, MD5)
   EXPECT_STREQ(u8"true", fields2[0].at(u8"stale").c_str());
 }
 
-TEST(HTTP_Auth, MD5_sess)
+TEST(HTTP_Server_Auth, MD5_sess)
 {
   constexpr const char cnonce[] = "not a good cnonce";
 
-  epee::net_utils::http::http_auth::login user{"foo", "bar"};
-  epee::net_utils::http::http_auth auth{user};
+  http::login user{"foo", "bar"};
+  http::http_server_auth auth{user};
 
   const auto response = auth.get_response(make_request(fields{}));
   ASSERT_TRUE(bool(response));
@@ -334,13 +371,13 @@ TEST(HTTP_Auth, MD5_sess)
   EXPECT_STREQ(u8"true", fields2[0].at(u8"stale").c_str());
 }
 
-TEST(HTTP_Auth, MD5_auth)
+TEST(HTTP_Server_Auth, MD5_auth)
 {
   constexpr const char cnonce[] = "not a nonce";
   constexpr const char qop[] = "auth";
 
-  epee::net_utils::http::http_auth::login user{"foo", "bar"};
-  epee::net_utils::http::http_auth auth{user};
+  http::login user{"foo", "bar"};
+  http::http_server_auth auth{user};
 
   const auto response = auth.get_response(make_request(fields{}));
   ASSERT_TRUE(bool(response));
@@ -402,13 +439,13 @@ TEST(HTTP_Auth, MD5_auth)
   EXPECT_STREQ(u8"true", parsed_replay[0].at(u8"stale").c_str());
 }
 
-TEST(HTTP_Auth, MD5_sess_auth)
+TEST(HTTP_Server_Auth, MD5_sess_auth)
 {
   constexpr const char cnonce[] = "not a nonce";
   constexpr const char qop[] = "auth";
 
-  epee::net_utils::http::http_auth::login user{"foo", "bar"};
-  epee::net_utils::http::http_auth auth{user};
+  http::login user{"foo", "bar"};
+  http::http_server_auth auth{user};
 
   const auto response = auth.get_response(make_request(fields{}));
   ASSERT_TRUE(bool(response));
@@ -469,3 +506,219 @@ TEST(HTTP_Auth, MD5_sess_auth)
   EXPECT_NE(nonce, parsed_replay[0].at(u8"nonce"));
   EXPECT_STREQ(u8"true", parsed_replay[0].at(u8"stale").c_str());
 }
+
+
+TEST(HTTP_Auth, DogFood)
+{
+  const auto add_field = [] (http::http_request_info& request, http::http_client_auth& client)
+  {
+    auto field = client.get_auth_field(request.m_http_method_str, request.m_URI);
+    EXPECT_TRUE(bool(field));
+    if (!field)
+      return false;
+    request.m_header_info.m_etc_fields.push_back(std::move(*field));
+    return true;
+  };
+
+  const http::login user{"some_user", "ultimate password"};
+
+  http::http_server_auth server{user};
+  http::http_client_auth client{user};
+
+  http::http_request_info request{};
+  request.m_http_method_str = "GET";
+  request.m_URI = "/FOO";
+
+  const auto response = server.get_response(request);
+  ASSERT_TRUE(bool(response));
+  EXPECT_TRUE(is_unauthorized(*response));
+
+  EXPECT_EQ(http::http_client_auth::kSuccess, client.handle_401(*response));
+  EXPECT_TRUE(add_field(request, client));
+  EXPECT_FALSE(bool(server.get_response(request)));
+
+  for (unsigned i = 0; i < 1000; ++i)
+  {
+    request.m_http_method_str += std::to_string(i);
+    request.m_header_info.m_etc_fields.clear();
+    EXPECT_TRUE(add_field(request, client));
+    EXPECT_FALSE(bool(server.get_response(request)));
+  }
+
+  // resetting counter should be rejected by server
+  request.m_header_info.m_etc_fields.clear();
+  client = http::http_client_auth{user};
+  EXPECT_EQ(http::http_client_auth::kSuccess, client.handle_401(*response));
+  EXPECT_TRUE(add_field(request, client));
+
+  const auto response2 = server.get_response(request);
+  ASSERT_TRUE(bool(response2));
+  EXPECT_TRUE(is_unauthorized(*response2));
+
+  const auth_responses parsed1 = parse_response(*response);
+  const auth_responses parsed2 = parse_response(*response2);
+  ASSERT_LE(1u, parsed1.size());
+  ASSERT_LE(1u, parsed2.size());
+  EXPECT_NE(parsed1[0].at(u8"nonce"), parsed2[0].at(u8"nonce"));
+
+  // with stale=true client should reset
+  request.m_header_info.m_etc_fields.clear();
+  EXPECT_EQ(http::http_client_auth::kSuccess, client.handle_401(*response2));
+  EXPECT_TRUE(add_field(request, client));
+  EXPECT_FALSE(bool(server.get_response(request)));
+
+  // client should give up if stale=false
+  EXPECT_EQ(http::http_client_auth::kBadPassword, client.handle_401(*response));
+}
+
+TEST(HTTP_Client_Auth, Unavailable)
+{
+  http::http_client_auth auth{};
+  EXPECT_EQ(http::http_client_auth::kBadPassword, auth.handle_401(http::http_response_info{}));
+  EXPECT_FALSE(bool(auth.get_auth_field("GET", "/file")));
+}
+
+TEST(HTTP_Client_Auth, MissingAuthenticate)
+{
+  http::http_client_auth auth{{"foo", "bar"}};
+  EXPECT_EQ(http::http_client_auth::kParseFailure, auth.handle_401(http::http_response_info{}));
+  EXPECT_FALSE(bool(auth.get_auth_field("POST", "/\xFFname")));
+  {
+    http::http_response_info response{};
+    response.m_additional_fields.push_back({"\xFF", "\xFF"});
+    EXPECT_EQ(http::http_client_auth::kParseFailure, auth.handle_401(response));
+  }
+  EXPECT_FALSE(bool(auth.get_auth_field("DELETE", "/file/does/not/exist")));
+}
+
+TEST(HTTP_Client_Auth, BadSyntax)
+{
+  http::http_client_auth auth{{"foo", "bar"}};
+  EXPECT_EQ(http::http_client_auth::kParseFailure, auth.handle_401(make_response({{{u8"realm", "fo\xFF"}}})));
+  EXPECT_EQ(http::http_client_auth::kParseFailure, auth.handle_401(make_response({{{u8"domain", "fo\xFF"}}})));
+  EXPECT_EQ(http::http_client_auth::kParseFailure, auth.handle_401(make_response({{{u8"nonce", "fo\xFF"}}})));
+  EXPECT_EQ(http::http_client_auth::kParseFailure, auth.handle_401(make_response({{{u8"nonce \xFF =", "fo\xFF"}}})));
+  EXPECT_EQ(http::http_client_auth::kParseFailure, auth.handle_401(make_response({{{u8" \xFF nonce", "fo\xFF"}}})));
+}
+
+TEST(HTTP_Client_Auth, MD5)
+{
+  constexpr char method[] = "NOP";
+  constexpr char nonce[] = "some crazy nonce";
+  constexpr char realm[] = "the only realm";
+  constexpr char uri[] = "/some_file";
+
+  const http::login user{"foo", "bar"};
+  http::http_client_auth auth{user};
+
+  auto response = make_response({
+    {
+      {u8"domain", quoted("ignored")},
+      {u8"nonce", quoted(nonce)},
+      {u8"REALM", quoted(realm)}
+    },
+    {
+      {u8"algorithm", "null"},
+      {u8"domain", quoted("ignored")},
+      {u8"nonce", quoted(std::string{"e"} + nonce)},
+      {u8"realm", quoted(std::string{"e"} + realm)}
+    },
+  });
+
+  EXPECT_EQ(http::http_client_auth::kSuccess, auth.handle_401(response));
+  const auto auth_field = auth.get_auth_field(method, uri);
+  ASSERT_TRUE(bool(auth_field));
+
+  const auto parsed = parse_fields(auth_field->second);
+  EXPECT_STREQ(u8"Authorization", auth_field->first.c_str());
+  EXPECT_EQ(parsed.end(), parsed.find(u8"opaque"));
+  EXPECT_EQ(parsed.end(), parsed.find(u8"qop"));
+  EXPECT_EQ(parsed.end(), parsed.find(u8"nc"));
+  EXPECT_STREQ(u8"MD5", parsed.at(u8"algorithm").c_str());
+  EXPECT_STREQ(nonce, parsed.at(u8"nonce").c_str());
+  EXPECT_STREQ(uri, parsed.at(u8"uri").c_str());
+  EXPECT_EQ(user.username, parsed.at(u8"username"));
+  EXPECT_STREQ(realm, parsed.at(u8"realm").c_str());
+
+  const std::string a1 = get_a1(user, parsed);
+  const std::string a2 = get_a2(uri);
+  const std::string auth_code = md5_hex(
+    boost::join(std::vector<std::string>{md5_hex(a1), nonce, md5_hex(a2)}, u8":")
+  );
+  EXPECT_TRUE(boost::iequals(auth_code, parsed.at(u8"response")));
+  {
+    const auto auth_field_dup = auth.get_auth_field(method, uri);
+    ASSERT_TRUE(bool(auth_field_dup));
+    EXPECT_EQ(*auth_field, *auth_field_dup);
+  }
+
+
+  EXPECT_EQ(http::http_client_auth::kBadPassword, auth.handle_401(response));
+  response.m_additional_fields.front().second.append(u8"," + write_fields({{u8"stale", u8"TRUE"}}));
+  EXPECT_EQ(http::http_client_auth::kSuccess, auth.handle_401(response));
+}
+
+TEST(HTTP_Client_Auth, MD5_auth)
+{
+  constexpr char cnonce[] = "";
+  constexpr char method[] = "NOP";
+  constexpr char nonce[] = "some crazy nonce";
+  constexpr char opaque[] = "this is the opaque";
+  constexpr char qop[] = u8"ignore,auth,ignore";
+  constexpr char realm[] = "the only realm";
+  constexpr char uri[] = "/some_file";
+
+  const http::login user{"foo", "bar"};
+  http::http_client_auth auth{user};
+
+  auto response = make_response({
+    {
+      {u8"algorithm", u8"MD5"},
+      {u8"domain", quoted("ignored")},
+      {u8"nonce", quoted(std::string{"e"} + nonce)},
+      {u8"realm", quoted(std::string{"e"} + realm)},
+      {u8"qop", quoted("some,thing,to,ignore")}
+    },
+    {
+      {u8"algorIthm", quoted(u8"md5")},
+      {u8"domain", quoted("ignored")},
+      {u8"noNce", quoted(nonce)},
+      {u8"opaque", quoted(opaque)},
+      {u8"realm", quoted(realm)},
+      {u8"QoP", quoted(qop)}
+    }
+  });
+
+  EXPECT_EQ(http::http_client_auth::kSuccess, auth.handle_401(response));
+
+  for (unsigned i = 1; i < 1000; ++i)
+  {
+    const std::string nc = get_nc(i);
+
+    const auto auth_field = auth.get_auth_field(method, uri);
+    ASSERT_TRUE(bool(auth_field));
+
+    const auto parsed = parse_fields(auth_field->second);
+    EXPECT_STREQ(u8"Authorization", auth_field->first.c_str());
+    EXPECT_STREQ(u8"MD5", parsed.at(u8"algorithm").c_str());
+    EXPECT_STREQ(nonce, parsed.at(u8"nonce").c_str());
+    EXPECT_STREQ(opaque, parsed.at(u8"opaque").c_str());
+    EXPECT_STREQ(u8"auth", parsed.at(u8"qop").c_str());
+    EXPECT_STREQ(uri, parsed.at(u8"uri").c_str());
+    EXPECT_EQ(user.username, parsed.at(u8"username"));
+    EXPECT_STREQ(realm, parsed.at(u8"realm").c_str());
+    EXPECT_EQ(nc, parsed.at(u8"nc"));
+
+    const std::string a1 = get_a1(user, parsed);
+    const std::string a2 = get_a2(uri);
+    const std::string auth_code = md5_hex(
+      boost::join(std::vector<std::string>{md5_hex(a1), nonce, nc, cnonce, u8"auth", md5_hex(a2)}, u8":")
+    );
+    EXPECT_TRUE(boost::iequals(auth_code, parsed.at(u8"response")));
+  }
+
+  EXPECT_EQ(http::http_client_auth::kBadPassword, auth.handle_401(response));
+  response.m_additional_fields.back().second.append(u8"," + write_fields({{u8"stale", u8"trUe"}}));
+  EXPECT_EQ(http::http_client_auth::kSuccess, auth.handle_401(response));
+}
+