Add support for upload handlers and implement brep-upload-bindist handler

14 files changed, 1705 insertions, 407 deletions

diff --git a/mod/build-config-module.cxx b/mod/build-config-module.cxx
index 6ad2d73..97c9f9e 100644
--- a/mod/build-config-module.cxx
+++ b/mod/build-config-module.cxx
@@ -108,7 +108,7 @@ namespace brep
     catch (const system_error& e)
     {
       ostringstream os;
-      os<< "unable to iterate over agents keys directory '" << d << "'";
+      os << "unable to iterate over agents keys directory '" << d << "'";
       throw_generic_error (e.code ().value (), os.str ().c_str ());
     }
 
diff --git a/mod/build-result-module.cxx b/mod/build-result-module.cxx
new file mode 100644
index 0000000..7823e3a
--- /dev/null
+++ b/mod/build-result-module.cxx
@@ -0,0 +1,284 @@
+// file      : mod/build-result-module.cxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#include <mod/build-result-module.hxx>
+
+#include <libbutl/openssl.hxx>
+#include <libbutl/process-io.hxx>
+
+namespace brep
+{
+  using namespace std;
+  using namespace butl;
+
+  // While currently the user-defined copy constructor is not required (we
+  // don't need to deep copy nullptr's), it is a good idea to keep the
+  // placeholder ready for less trivial cases.
+  //
+  build_result_module::
+  build_result_module (const build_result_module& r)
+      : database_module (r),
+        build_config_module (r),
+        use_openssl_pkeyutl_ (r.initialized_ ? r.use_openssl_pkeyutl_ : false)
+  {
+  }
+
+  void build_result_module::
+  init (const options::build& bo, const options::build_db& bdo)
+  {
+    HANDLER_DIAG;
+
+    build_config_module::init (bo);
+    database_module::init (bdo, bdo.build_db_retry ());
+
+    try
+    {
+      optional<openssl_info> oi (
+        openssl::info ([&trace, this] (const char* args[], size_t n)
+                       {
+                         l2 ([&]{trace << process_args {args, n};});
+                       },
+                       2,
+                       bo.openssl ()));
+
+      use_openssl_pkeyutl_ = oi                    &&
+                             oi->name == "OpenSSL" &&
+                             oi->version >= semantic_version {3, 0, 0};
+    }
+    catch (const system_error& e)
+    {
+      fail << "unable to obtain openssl version: " << e;
+    }
+  }
+
+  build_result_module::parse_session_result build_result_module::
+  parse_session (const string& s) const
+  {
+    using brep::version; // Not to confuse with module::version.
+
+    parse_session_result r;
+
+    size_t p (s.find ('/')); // End of tenant.
+
+    if (p == string::npos)
+      throw invalid_argument ("no package name");
+
+    if (tenant.compare (0, tenant.size (), s, 0, p) != 0)
+      throw invalid_argument ("tenant mismatch");
+
+    size_t b (p + 1);    // Start of package name.
+    p = s.find ('/', b); // End of package name.
+
+    if (p == b)
+      throw invalid_argument ("empty package name");
+
+    if (p == string::npos)
+      throw invalid_argument ("no package version");
+
+    package_name name;
+
+    try
+    {
+      name = package_name (string (s, b, p - b));
+    }
+    catch (const invalid_argument& e)
+    {
+      throw invalid_argument (
+        string ("invalid package name : ") + e.what ());
+    }
+
+    b = p + 1;           // Start of version.
+    p = s.find ('/', b); // End of version.
+
+    if (p == string::npos)
+      throw invalid_argument ("no target");
+
+    auto parse_version = [&s, &b, &p] (const char* what) -> version
+    {
+      // Intercept exception handling to add the parsing error attribution.
+      //
+      try
+      {
+        return brep::version (string (s, b, p - b));
+      }
+      catch (const invalid_argument& e)
+      {
+        throw invalid_argument (
+          string ("invalid ") + what + ": " + e.what ());
+      }
+    };
+
+    r.package_version = parse_version ("package version");
+
+    b = p + 1;           // Start of target.
+    p = s.find ('/', b); // End of target.
+
+    if (p == string::npos)
+      throw invalid_argument ("no target configuration name");
+
+    target_triplet target;
+    try
+    {
+      target = target_triplet (string (s, b, p - b));
+    }
+    catch (const invalid_argument& e)
+    {
+      throw invalid_argument (string ("invalid target: ") + e.what ());
+    }
+
+    b = p + 1;           // Start of target configuration name.
+    p = s.find ('/', b); // End of target configuration name.
+
+    if (p == string::npos)
+      throw invalid_argument ("no package configuration name");
+
+    string target_config (s, b, p - b);
+
+    if (target_config.empty ())
+      throw invalid_argument ("empty target configuration name");
+
+    b = p + 1;           // Start of package configuration name.
+    p = s.find ('/', b); // End of package configuration name.
+
+    if (p == string::npos)
+      throw invalid_argument ("no toolchain name");
+
+    string package_config (s, b, p - b);
+
+    if (package_config.empty ())
+      throw invalid_argument ("empty package configuration name");
+
+    b = p + 1;           // Start of toolchain name.
+    p = s.find ('/', b); // End of toolchain name.
+
+    if (p == string::npos)
+      throw invalid_argument ("no toolchain version");
+
+    string toolchain_name (s, b, p - b);
+
+    if (toolchain_name.empty ())
+      throw invalid_argument ("empty toolchain name");
+
+    b = p + 1;           // Start of toolchain version.
+    p = s.find ('/', b); // End of toolchain version.
+
+    if (p == string::npos)
+      throw invalid_argument ("no timestamp");
+
+    r.toolchain_version = parse_version ("toolchain version");
+
+    r.id = build_id (package_id (move (tenant), move (name), r.package_version),
+                     move (target),
+                     move (target_config),
+                     move (package_config),
+                     move (toolchain_name),
+                     r.toolchain_version);
+
+    try
+    {
+      size_t tsn;
+      string ts (s, p + 1);
+
+      r.timestamp = timestamp (chrono::duration_cast<timestamp::duration> (
+                                 chrono::nanoseconds (stoull (ts, &tsn))));
+
+      if (tsn != ts.size ())
+        throw invalid_argument ("trailing junk");
+    }
+    // Handle invalid_argument or out_of_range (both derive from logic_error),
+    // that can be thrown by stoull().
+    //
+    catch (const logic_error& e)
+    {
+      throw invalid_argument (string ("invalid timestamp: ") + e.what ());
+    }
+
+    return r;
+  }
+
+  bool build_result_module::
+  authenticate_session (const options::build& o,
+                        const optional<vector<char>>& challenge,
+                        const build& b,
+                        const string& session) const
+  {
+    HANDLER_DIAG;
+
+    auto warn_auth = [&session, &warn] (const string& d)
+    {
+      warn << "session '" << session << "' authentication failed: " << d;
+    };
+
+    bool r (false);
+
+    // Must both be present or absent.
+    //
+    if (!b.agent_challenge != !challenge)
+    {
+      warn_auth (challenge ? "unexpected challenge": "challenge is expected");
+    }
+    else if (bot_agent_key_map_ == nullptr) // Authentication is disabled.
+    {
+      r = true;
+    }
+    else if (!b.agent_challenge) // Authentication is recently enabled.
+    {
+      warn_auth ("challenge is required now");
+    }
+    else
+    {
+      assert (b.agent_fingerprint && challenge);
+      auto i (bot_agent_key_map_->find (*b.agent_fingerprint));
+
+      // The agent's key is recently replaced.
+      //
+      if (i == bot_agent_key_map_->end ())
+      {
+        warn_auth ("agent's public key not found");
+      }
+      else
+      try
+      {
+        openssl os ([&trace, this] (const char* args[], size_t n)
+                    {
+                      l2 ([&]{trace << process_args {args, n};});
+                    },
+                    path ("-"), fdstream_mode::text, 2,
+                    process_env (o.openssl (), o.openssl_envvar ()),
+                    use_openssl_pkeyutl_ ? "pkeyutl" : "rsautl",
+                    o.openssl_option (),
+                    use_openssl_pkeyutl_ ? "-verifyrecover" : "-verify",
+                    "-pubin",
+                    "-inkey",
+                    i->second);
+
+        for (const auto& c: *challenge)
+          os.out.put (c); // Sets badbit on failure.
+
+        os.out.close ();
+
+        string s;
+        getline (os.in, s);
+
+        bool v (os.in.eof ());
+        os.in.close ();
+
+        if (os.wait () && v)
+        {
+          r = (s == *b.agent_challenge);
+
+          if (!r)
+            warn_auth ("challenge mismatched");
+        }
+        else // The signature is presumably meaningless.
+          warn_auth ("unable to verify challenge");
+      }
+      catch (const system_error& e)
+      {
+        fail << "unable to verify challenge: " << e;
+      }
+    }
+
+    return r;
+  }
+}
diff --git a/mod/build-result-module.hxx b/mod/build-result-module.hxx
new file mode 100644
index 0000000..e0f1eef
--- /dev/null
+++ b/mod/build-result-module.hxx
@@ -0,0 +1,76 @@
+// file      : mod/build-result-module.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef MOD_BUILD_RESULT_MODULE_HXX
+#define MOD_BUILD_RESULT_MODULE_HXX
+
+#include <libbrep/types.hxx>
+#include <libbrep/utility.hxx>
+
+#include <libbrep/build.hxx>
+
+#include <mod/module-options.hxx>
+#include <mod/database-module.hxx>
+#include <mod/build-config-module.hxx>
+
+namespace brep
+{
+  // Base class for modules that handle the build task results.
+  //
+  // Specifically, it loads build controller configuration, initializes the
+  // build database instance, and provides utilities for parsing and
+  // authenticating the build task session.
+  //
+  class build_result_module: public database_module,
+                             protected build_config_module
+  {
+  protected:
+    build_result_module () = default;
+
+    // Create a shallow copy (handling instance) if initialized and a deep
+    // copy (context exemplar) otherwise.
+    //
+    explicit
+    build_result_module (const build_result_module&);
+
+    void
+    init (const options::build&, const options::build_db&);
+
+    // Parse the build task session and verify that the session matches the
+    // tenant. Throw invalid_argument on errors.
+    //
+    struct parse_session_result
+    {
+      build_id id;
+      brep::version package_version;
+      brep::version toolchain_version;
+      brep::timestamp timestamp;
+    };
+
+    parse_session_result
+    parse_session (const string&) const;
+
+    // Return true if bbot agent authentication is disabled or the agent is
+    // recognized and challenge matches. If the session authentication fails
+    // (challenge is not expected, expected but doesn't match, etc), then log
+    // the failure reason with the warning severity and return false.
+    //
+    // Note that the session argument is used only for logging.
+    //
+    bool
+    authenticate_session (const options::build&,
+                          const optional<vector<char>>& challenge,
+                          const build&,
+                          const string& session) const;
+
+  protected:
+    // True if the openssl version is greater or equal to 3.0.0 and so pkeyutl
+    // needs to be used instead of rsautl.
+    //
+    // Note that openssl 3.0.0 deprecates rsautl in favor of pkeyutl.
+    //
+    bool use_openssl_pkeyutl_;
+  };
+}
+
+#endif // MOD_BUILD_RESULT_MODULE_HXX
diff --git a/mod/mod-build-result.cxx b/mod/mod-build-result.cxx
index 99bdc8d..7806cda 100644
--- a/mod/mod-build-result.cxx
+++ b/mod/mod-build-result.cxx
@@ -6,7 +6,6 @@
 #include <odb/database.hxx>
 #include <odb/transaction.hxx>
 
-#include <libbutl/openssl.hxx>
 #include <libbutl/sendmail.hxx>
 #include <libbutl/fdstream.hxx>
 #include <libbutl/process-io.hxx>
@@ -38,10 +37,8 @@ using namespace odb::core;
 //
 brep::build_result::
 build_result (const build_result& r)
-    : database_module (r),
-      build_config_module (r),
-      options_ (r.initialized_ ? r.options_  : nullptr),
-      use_openssl_pkeyutl_ (r.initialized_ ? r.use_openssl_pkeyutl_ : false)
+    : build_result_module (r),
+      options_ (r.initialized_ ? r.options_  : nullptr)
 {
 }
 
@@ -53,34 +50,12 @@ init (scanner& s)
   options_ = make_shared<options::build_result> (
     s, unknown_mode::fail, unknown_mode::fail);
 
-  database_module::init (static_cast<const options::package_db&> (*options_),
-                         options_->package_db_retry ());
-
   if (options_->build_config_specified ())
   {
-    database_module::init (static_cast<const options::build_db&> (*options_),
-                           options_->build_db_retry ());
-
-    build_config_module::init (*options_);
-  }
+    build_result_module::init (*options_, *options_);
 
-  try
-  {
-    optional<openssl_info> oi (
-      openssl::info ([&trace, this] (const char* args[], size_t n)
-                     {
-                       l2 ([&]{trace << process_args {args, n};});
-                     },
-                     2,
-                     options_->openssl ()));
-
-    use_openssl_pkeyutl_ = oi                    &&
-                           oi->name == "OpenSSL" &&
-                           oi->version >= semantic_version {3, 0, 0};
-  }
-  catch (const system_error& e)
-  {
-    fail << "unable to obtain openssl version: " << e;
+    database_module::init (static_cast<const options::package_db&> (*options_),
+                           options_->package_db_retry ());
   }
 
   if (options_->root ().empty ())
@@ -129,149 +104,23 @@ handle (request& rq, response&)
     throw invalid_request (400, e.what ());
   }
 
-  // Parse the task response session to obtain the build id and the timestamp,
-  // and to make sure the session matches tenant and the result manifest's
-  // package name, and version.
+  // Parse the task response session and make sure the session matches tenant
+  // and the result manifest's package name, and version.
   //
-  build_id id;
-  timestamp session_timestamp;
+  parse_session_result session;
+  const build_id& id (session.id);
 
   try
   {
-    const string& s (rqm.session);
-
-    size_t p (s.find ('/')); // End of tenant.
-
-    if (p == string::npos)
-      throw invalid_argument ("no package name");
-
-    if (tenant.compare (0, tenant.size (), s, 0, p) != 0)
-      throw invalid_argument ("tenant mismatch");
-
-    size_t b (p + 1);    // Start of package name.
-    p = s.find ('/', b); // End of package name.
-
-    if (p == b)
-      throw invalid_argument ("empty package name");
-
-    if (p == string::npos)
-      throw invalid_argument ("no package version");
-
-    package_name& name (rqm.result.name);
-    {
-      const string& n (name.string ());
-      if (n.compare (0, n.size (), s, b, p - b) != 0)
-        throw invalid_argument ("package name mismatch");
-    }
-
-    b = p + 1;           // Start of version.
-    p = s.find ('/', b); // End of version.
-
-    if (p == string::npos)
-      throw invalid_argument ("no configuration name");
-
-    auto parse_version = [&s, &b, &p] (const char* what) -> version
-    {
-      // Intercept exception handling to add the parsing error attribution.
-      //
-      try
-      {
-        return brep::version (string (s, b, p - b));
-      }
-      catch (const invalid_argument& e)
-      {
-        throw invalid_argument (string ("invalid ") + what + ": " + e.what ());
-      }
-    };
+    // Note: also verifies that the tenant matches the session.
+    //
+    session = parse_session (rqm.session);
 
-    version package_version (parse_version ("package version"));
+    if (rqm.result.name != id.package.name)
+      throw invalid_argument ("package name mismatch");
 
-    if (package_version != rqm.result.version)
+    if (rqm.result.version != session.package_version)
       throw invalid_argument ("package version mismatch");
-
-    b = p + 1;           // Start of target.
-    p = s.find ('/', b); // End of target.
-
-    if (p == string::npos)
-      throw invalid_argument ("no target configuration name");
-
-    target_triplet target;
-    try
-    {
-      target = target_triplet (string (s, b, p - b));
-    }
-    catch (const invalid_argument& e)
-    {
-      throw invalid_argument (string ("invalid target: ") + e.what ());
-    }
-
-    b = p + 1;           // Start of target configuration name.
-    p = s.find ('/', b); // End of target configuration name.
-
-    if (p == string::npos)
-      throw invalid_argument ("no package configuration name");
-
-    string target_config (s, b, p - b);
-
-    if (target_config.empty ())
-      throw invalid_argument ("empty target configuration name");
-
-    b = p + 1;           // Start of package configuration name.
-    p = s.find ('/', b); // End of package configuration name.
-
-    if (p == string::npos)
-      throw invalid_argument ("no toolchain name");
-
-    string package_config (s, b, p - b);
-
-    if (package_config.empty ())
-      throw invalid_argument ("empty package configuration name");
-
-    b = p + 1;           // Start of toolchain name.
-    p = s.find ('/', b); // End of toolchain name.
-
-    if (p == string::npos)
-      throw invalid_argument ("no toolchain version");
-
-    string toolchain_name (s, b, p - b);
-
-    if (toolchain_name.empty ())
-      throw invalid_argument ("empty toolchain name");
-
-    b = p + 1;           // Start of toolchain version.
-    p = s.find ('/', b); // End of toolchain version.
-
-    if (p == string::npos)
-      throw invalid_argument ("no timestamp");
-
-    version toolchain_version (parse_version ("toolchain version"));
-
-    id = build_id (package_id (move (tenant), move (name), package_version),
-                   move (target),
-                   move (target_config),
-                   move (package_config),
-                   move (toolchain_name),
-                   toolchain_version);
-
-    try
-    {
-      size_t tsn;
-      string ts (s, p + 1);
-
-      session_timestamp = timestamp (
-        chrono::duration_cast<timestamp::duration> (
-          chrono::nanoseconds (stoull (ts, &tsn))));
-
-      if (tsn != ts.size ())
-        throw invalid_argument ("trailing junk");
-    }
-    // Handle invalid_argument or out_of_range (both derive from logic_error),
-    // that can be thrown by stoull().
-    //
-    catch (const logic_error& e)
-    {
-      throw invalid_argument (string ("invalid timestamp: ") + e.what ());
-    }
   }
   catch (const invalid_argument& e)
   {
@@ -341,6 +190,12 @@ handle (request& rq, response&)
   bool build_notify (false);
   bool unforced (true);
 
+  // Note that if the session authentication fails (probably due to the
+  // authentication settings change), then we log this case with the warning
+  // severity and respond with the 200 HTTP code as if the challenge is
+  // valid. The thinking is that we shouldn't alarm a law-abaiding agent and
+  // shouldn't provide any information to a malicious one.
+  //
   {
     transaction t (build_db_->begin ());
 
@@ -348,251 +203,174 @@ handle (request& rq, response&)
     shared_ptr<build> b;
     if (!build_db_->query_one<package_build> (
           query<package_build>::build::id == id, pb))
+    {
       warn_expired ("no package build");
+    }
     else if ((b = move (pb.build))->state != build_state::building)
+    {
       warn_expired ("package configuration state is " + to_string (b->state));
-    else if (b->timestamp != session_timestamp)
+    }
+    else if (b->timestamp != session.timestamp)
+    {
       warn_expired ("non-matching timestamp");
-    else
+    }
+    else if (authenticate_session (*options_, rqm.challenge, *b, rqm.session))
     {
-      // Check the challenge.
+      // If the build is interrupted, then revert it to the original built
+      // state if this is a rebuild and delete it from the database otherwise.
       //
-      // If the challenge doesn't match expectations (probably due to the
-      // authentication settings change), then we log this case with the
-      // warning severity and respond with the 200 HTTP code as if the
-      // challenge is valid. The thinking is that we shouldn't alarm a
-      // law-abaiding agent and shouldn't provide any information to a
-      // malicious one.
-      //
-      auto warn_auth = [&rqm, &warn] (const string& d)
+      if (rqm.result.status == result_status::interrupt)
       {
-        warn << "session '" << rqm.session << "' authentication failed: " << d;
-      };
+        if (b->status) // Is this a rebuild?
+        {
+          b->state = build_state::built;
 
-      bool auth (false);
+          // Keep the force rebuild indication. Note that the forcing state is
+          // only valid for the building state.
+          //
+          if (b->force == force_state::forcing)
+            b->force = force_state::forced;
 
-      // Must both be present or absent.
-      //
-      if (!b->agent_challenge != !rqm.challenge)
-        warn_auth (rqm.challenge
-                   ? "unexpected challenge"
-                   : "challenge is expected");
-      else if (bot_agent_key_map_ == nullptr) // Authentication is disabled.
-        auth = true;
-      else if (!b->agent_challenge) // Authentication is recently enabled.
-        warn_auth ("challenge is required now");
-      else
-      {
-        assert (b->agent_fingerprint && rqm.challenge);
-        auto i (bot_agent_key_map_->find (*b->agent_fingerprint));
+          // Cleanup the interactive build login information.
+          //
+          b->interactive = nullopt;
 
-        // The agent's key is recently replaced.
-        //
-        if (i == bot_agent_key_map_->end ())
-          warn_auth ("agent's public key not found");
-        else
-        {
-          try
-          {
-            openssl os (print_args,
-                        path ("-"), fdstream_mode::text, 2,
-                        process_env (options_->openssl (),
-                                     options_->openssl_envvar ()),
-                        use_openssl_pkeyutl_ ? "pkeyutl" : "rsautl",
-                        options_->openssl_option (),
-                        use_openssl_pkeyutl_ ? "-verifyrecover" : "-verify",
-                        "-pubin",
-                        "-inkey",
-                        i->second);
-
-            for (const auto& c: *rqm.challenge)
-              os.out.put (c); // Sets badbit on failure.
-
-            os.out.close ();
-
-            string s;
-            getline (os.in, s);
-
-            bool v (os.in.eof ());
-            os.in.close ();
-
-            if (os.wait () && v)
-            {
-              auth = s == *b->agent_challenge;
-
-              if (!auth)
-                warn_auth ("challenge mismatched");
-            }
-            else // The signature is presumably meaningless.
-              warn_auth ("unable to verify challenge");
-          }
-          catch (const system_error& e)
-          {
-            fail << "unable to verify challenge: " << e;
-          }
+          // Cleanup the authentication data.
+          //
+          b->agent_fingerprint = nullopt;
+          b->agent_challenge = nullopt;
+
+          // Note that we are unable to restore the pre-rebuild timestamp
+          // since it has been overwritten when the build task was issued.
+          // That, however, feels ok and we just keep it unchanged.
+
+          build_db_->update (b);
         }
+        else
+          build_db_->erase (b);
       }
-
-      if (auth)
+      else
       {
-        // If the build is interrupted, then revert it to the original built
-        // state if this is a rebuild and delete it from the database
-        // otherwise.
+        // Verify the result status/checksums.
         //
-        if (rqm.result.status == result_status::interrupt)
+        // Specifically, if the result status is skip, then it can only be in
+        // response to the soft rebuild task (all checksums are present in the
+        // build object) and the result checksums must match the build object
+        // checksums. On verification failure respond with the bad request
+        // HTTP code (400).
+        //
+        if (rqm.result.status == result_status::skip)
         {
-          if (b->status) // Is this a rebuild?
-          {
-            b->state = build_state::built;
+          if (!b->agent_checksum  ||
+              !b->worker_checksum ||
+              !b->dependency_checksum)
+            throw invalid_request (400, "unexpected skip result status");
+
+          // Can only be absent for initial build, in which case the
+          // checksums are also absent and we would end up with the above
+          // 400 response.
+          //
+          assert (b->status);
 
-            // Keep the force rebuild indication. Note that the forcing state
-            // is only valid for the building state.
-            //
-            if (b->force == force_state::forcing)
-              b->force = force_state::forced;
+          // Verify that the result checksum matches the build checksum and
+          // throw invalid_request(400) if that's not the case.
+          //
+          auto verify = [] (const string& build_checksum,
+                            const optional<string>& result_checksum,
+                            const char* what)
+          {
+            if (!result_checksum)
+              throw invalid_request (
+                400,
+                string (what) + " checksum is expected for skip result status");
+
+            if (*result_checksum != build_checksum)
+              throw invalid_request (
+                400,
+                string (what) + " checksum '" + build_checksum  +
+                "' is expected instead of '" + *result_checksum +
+                "' for skip result status");
+          };
+
+          verify (*b->agent_checksum, rqm.agent_checksum, "agent");
+
+          verify (*b->worker_checksum,
+                  rqm.result.worker_checksum,
+                  "worker");
+
+          verify (*b->dependency_checksum,
+                  rqm.result.dependency_checksum,
+                  "dependency");
+        }
 
-            // Cleanup the interactive build login information.
-            //
-            b->interactive = nullopt;
+        unforced = b->force == force_state::unforced;
 
-            // Cleanup the authentication data.
-            //
-            b->agent_fingerprint = nullopt;
-            b->agent_challenge = nullopt;
+        // Don't send email to the build-email address for the
+        // success-to-success status change, unless the build was forced.
+        //
+        build_notify = !(rqm.result.status == result_status::success &&
+                         b->status                                   &&
+                         *b->status == rqm.result.status             &&
+                         unforced);
 
-            // Note that we are unable to restore the pre-rebuild timestamp
-            // since it has been overwritten when the build task was issued.
-            // That, however, feels ok and we just keep it unchanged.
+        b->state  = build_state::built;
+        b->force  = force_state::unforced;
 
-            build_db_->update (b);
-          }
-          else
-            build_db_->erase (b);
-        }
-        else
-        {
-          // Verify the result status/checksums.
-          //
-          // Specifically, if the result status is skip, then it can only be
-          // in response to the soft rebuild task (all checksums are present
-          // in the build object) and the result checksums must match the
-          // build object checksums. On verification failure respond with the
-          // bad request HTTP code (400).
-          //
-          if (rqm.result.status == result_status::skip)
-          {
-            if (!b->agent_checksum  ||
-                !b->worker_checksum ||
-                !b->dependency_checksum)
-              throw invalid_request (400, "unexpected skip result status");
-
-            // Can only be absent for initial build, in which case the
-            // checksums are also absent and we would end up with the above
-            // 400 response.
-            //
-            assert (b->status);
-
-            // Verify that the result checksum matches the build checksum and
-            // throw invalid_request(400) if that's not the case.
-            //
-            auto verify = [] (const string& build_checksum,
-                              const optional<string>& result_checksum,
-                              const char* what)
-            {
-              if (!result_checksum)
-                throw invalid_request (
-                  400,
-                  string (what) +
-                  " checksum is expected for skip result status");
-
-              if (*result_checksum != build_checksum)
-                throw invalid_request (
-                  400,
-                  string (what) + " checksum '" + build_checksum  +
-                  "' is expected instead of '" + *result_checksum +
-                  "' for skip result status");
-            };
-
-            verify (*b->agent_checksum, rqm.agent_checksum, "agent");
-
-            verify (*b->worker_checksum,
-                    rqm.result.worker_checksum,
-                    "worker");
-
-            verify (*b->dependency_checksum,
-                    rqm.result.dependency_checksum,
-                    "dependency");
-          }
+        // Cleanup the interactive build login information.
+        //
+        b->interactive = nullopt;
 
-          unforced = b->force == force_state::unforced;
+        // Cleanup the authentication data.
+        //
+        b->agent_fingerprint = nullopt;
+        b->agent_challenge = nullopt;
 
-          // Don't send email to the build-email address for the
-          // success-to-success status change, unless the build was forced.
-          //
-          build_notify = !(rqm.result.status == result_status::success &&
-                           b->status                                   &&
-                           *b->status == rqm.result.status             &&
-                           unforced);
+        b->timestamp = system_clock::now ();
+        b->soft_timestamp = b->timestamp;
 
-          b->state  = build_state::built;
-          b->force  = force_state::unforced;
+        // If the result status is other than skip, then save the status,
+        // results, and checksums and update the hard timestamp.
+        //
+        if (rqm.result.status != result_status::skip)
+        {
+          b->status = rqm.result.status;
+          b->hard_timestamp = b->soft_timestamp;
 
-          // Cleanup the interactive build login information.
+          // Mark the section as loaded, so results are updated.
           //
-          b->interactive = nullopt;
+          b->results_section.load ();
+          b->results = move (rqm.result.results);
 
-          // Cleanup the authentication data.
+          // Save the checksums.
           //
-          b->agent_fingerprint = nullopt;
-          b->agent_challenge = nullopt;
+          b->agent_checksum      = move (rqm.agent_checksum);
+          b->worker_checksum     = move (rqm.result.worker_checksum);
+          b->dependency_checksum = move (rqm.result.dependency_checksum);
+        }
 
-          b->timestamp = system_clock::now ();
-          b->soft_timestamp = b->timestamp;
+        build_db_->update (b);
 
-          // If the result status is other than skip, then save the status,
-          // results, and checksums and update the hard timestamp.
-          //
-          if (rqm.result.status != result_status::skip)
-          {
-            b->status = rqm.result.status;
-            b->hard_timestamp = b->soft_timestamp;
-
-            // Mark the section as loaded, so results are updated.
-            //
-            b->results_section.load ();
-            b->results = move (rqm.result.results);
-
-            // Save the checksums.
-            //
-            b->agent_checksum      = move (rqm.agent_checksum);
-            b->worker_checksum     = move (rqm.result.worker_checksum);
-            b->dependency_checksum = move (rqm.result.dependency_checksum);
-          }
-
-          build_db_->update (b);
+        // Don't send the build notification email if the task result is
+        // `skip`, the configuration is hidden, or is now excluded by the
+        // package.
+        //
+        if (rqm.result.status != result_status::skip && belongs (*tc, "all"))
+        {
+          shared_ptr<build_package> p (
+            build_db_->load<build_package> (b->id.package));
 
-          // Don't send the build notification email if the task result is
-          // `skip`, the configuration is hidden, or is now excluded by the
-          // package.
+          // The package configuration should be present (see mod-builds.cxx
+          // for details) but if it is not, let's log the warning.
           //
-          if (rqm.result.status != result_status::skip && belongs (*tc, "all"))
+          if (const build_package_config* pc = find (b->package_config_name,
+                                                     p->configs))
           {
-            shared_ptr<build_package> p (
-              build_db_->load<build_package> (b->id.package));
-
-            // The package configuration should be present (see mod-builds.cxx
-            // for details) but if it is not, let's log the warning.
-            //
-            if (const build_package_config* pc = find (b->package_config_name,
-                                                       p->configs))
-            {
-              if (!exclude (*pc, p->builds, p->constraints, *tc))
-                bld = move (b);
-            }
-            else
-              warn << "cannot find configuration '" << b->package_config_name
-                   << "' for package " << p->id.name << '/' << p->version;
+            if (!exclude (*pc, p->builds, p->constraints, *tc))
+              bld = move (b);
           }
+          else
+            warn << "cannot find configuration '" << b->package_config_name
+                 << "' for package " << p->id.name << '/' << p->version;
         }
       }
     }
diff --git a/mod/mod-build-result.hxx b/mod/mod-build-result.hxx
index 1b32ad4..87ef1f2 100644
--- a/mod/mod-build-result.hxx
+++ b/mod/mod-build-result.hxx
@@ -8,12 +8,11 @@
 #include <libbrep/utility.hxx>
 
 #include <mod/module-options.hxx>
-#include <mod/database-module.hxx>
-#include <mod/build-config-module.hxx>
+#include <mod/build-result-module.hxx>
 
 namespace brep
 {
-  class build_result: public database_module, private build_config_module
+  class build_result: public build_result_module
   {
   public:
     build_result () = default;
@@ -36,13 +35,6 @@ namespace brep
 
   private:
     shared_ptr<options::build_result> options_;
-
-    // True if the openssl version is greater or equal to 3.0.0 and so pkeyutl
-    // needs to be used instead of rsautl.
-    //
-    // Note that openssl 3.0.0 deprecates rsautl in favor of pkeyutl.
-    //
-    bool use_openssl_pkeyutl_;
   };
 }
 
diff --git a/mod/mod-build-task.cxx b/mod/mod-build-task.cxx
index 33a7f58..4b0165f 100644
--- a/mod/mod-build-task.cxx
+++ b/mod/mod-build-task.cxx
@@ -286,15 +286,14 @@ handle (request& rq, response& rs)
                       b->toolchain_version.string () + '/' +
                       to_string (ts));
 
-      string result_url (options_->host () +
-                         tenant_dir (options_->root (), b->tenant).string () +
-                         "?build-result");
+      string tenant (tenant_dir (options_->root (), b->tenant).string ());
+      string result_url (options_->host () + tenant + "?build-result");
 
       assert (transaction::has_current ());
 
       assert (p->internal ()); // The package is expected to be buildable.
 
-      lazy_shared_ptr<build_repository> r (p->internal_repository.load ());
+      shared_ptr<build_repository> r (p->internal_repository.load ());
 
       strings fps;
       if (r->certificate_fingerprint)
@@ -369,9 +368,43 @@ handle (request& rq, response& rs)
                           move (t->interactive),
                           move (b->worker_checksum));
 
+      // Collect the build artifacts upload URLs, skipping those which are
+      // excluded with the upload-*-exclude configuration options.
+      //
+      vector<upload_url> upload_urls;
+
+      for (const auto& ud: options_->upload_data ())
+      {
+        const string& t (ud.first);
+
+        auto exclude = [&t] (const multimap<string, string>& mm,
+                             const string& v)
+        {
+          auto range (mm.equal_range (t));
+
+          for (auto i (range.first); i != range.second; ++i)
+          {
+            if (i->second == v)
+              return true;
+          }
+
+          return false;
+        };
+
+        if (!exclude (options_->upload_toolchain_exclude (),
+                      b->toolchain_name) &&
+            !exclude (options_->upload_repository_exclude (),
+                      r->canonical_name))
+        {
+          upload_urls.emplace_back (options_->host () + tenant + "?upload=" + t,
+                                    t);
+        }
+      }
+
       return task_response_manifest (move (session),
                                      move (b->agent_challenge),
                                      move (result_url),
+                                     move (upload_urls),
                                      move (b->agent_checksum),
                                      move (task));
     };
diff --git a/mod/mod-ci.cxx b/mod/mod-ci.cxx
index 68bb9be..df2365a 100644
--- a/mod/mod-ci.cxx
+++ b/mod/mod-ci.cxx
@@ -498,10 +498,6 @@ handle (request& rq, response& rs)
   // it's the 4XX (HTTP client error) status value, then we remove the
   // directory.
   //
-  // Note that leaving the directory in place in case of a submission error
-  // would have prevent the user from re-submitting until we research the
-  // issue and manually remove the directory.
-  //
   auto stash_submit_dir = [&dd, error] ()
   {
     if (dir_exists (dd))
@@ -520,7 +516,7 @@ handle (request& rq, response& rs)
 
   // Run the submission handler, if specified, reading the result manifest
   // from its stdout and caching it as a name/value pair list for later use
-  // (forwarding to the client, sending via email, etc.). Otherwise, create
+  // (forwarding to the client, sending via email, etc). Otherwise, create
   // implied result manifest.
   //
   status_code sc;
@@ -598,8 +594,10 @@ handle (request& rq, response& rs)
     // Remove the directory if the client error is detected.
     //
     if (sc >= 400 && sc < 500)
+    {
       rmdir_r (dd);
-
+    }
+    //
     // Otherwise, save the result manifest, into the directory. Also stash the
     // directory for troubleshooting in case of the server error.
     //
diff --git a/mod/mod-package-version-details.cxx b/mod/mod-package-version-details.cxx
index 3a6ef1f..e47d9b4 100644
--- a/mod/mod-package-version-details.cxx
+++ b/mod/mod-package-version-details.cxx
@@ -9,6 +9,8 @@
 #include <odb/database.hxx>
 #include <odb/transaction.hxx>
 
+#include <libbutl/filesystem.hxx> // dir_iterator, dir_entry
+
 #include <web/server/module.hxx>
 #include <web/server/mime-url-encoding.hxx>
 
@@ -47,6 +49,12 @@ init (scanner& s)
   options_ = make_shared<options::package_version_details> (
     s, unknown_mode::fail, unknown_mode::fail);
 
+  // Verify that the bindist-url option is specified when necessary.
+  //
+  if (options_->bindist_root_specified () &&
+      !options_->bindist_url_specified ())
+    fail << "bindist-url must be specified if bindist-root is specified";
+
   database_module::init (static_cast<const options::package_db&> (*options_),
                          options_->package_db_retry ());
 
@@ -187,8 +195,8 @@ handle (request& rq, response& rs)
     const string what (title + " description");
 
     s << (full
-          ? DIV_TEXT (*d, *
-                      pkg->description_type,
+          ? DIV_TEXT (*d,
+                      *pkg->description_type,
                       true /* strip_title */,
                       id,
                       what,
@@ -526,6 +534,168 @@ handle (request& rq, response& rs)
 
   t.commit ();
 
+  // Display the binary distribution packages for this tenant, package, and
+  // version, if present. Print the archive distributions last.
+  //
+  if (options_->bindist_root_specified ())
+  {
+    // Collect all the available package configurations by iterating over the
+    // <distribution> and <os-release> subdirectories and the <package-config>
+    // symlinks in the following filesystem hierarchy:
+    //
+    // [<tenant>/]<distribution>/<os-release>/<project>/<package>/<version>/<package-config>
+    //
+    // Note that it is possible that new directories and symlinks are created
+    // and/or removed while we iterate over the filesystem entries in the
+    // above hierarchy, which may result with system_error exceptions. If that
+    // happens, we just ignore such exceptions, trying to collect what we can.
+    //
+    const dir_path& br (options_->bindist_root ());
+
+    dir_path d (br);
+
+    if (!tenant.empty ())
+      d /= tenant;
+
+    // Note that distribution and os_release are simple paths and the
+    // config_symlink and config_dir are relative to the bindist root
+    // directory.
+    //
+    struct bindist_config
+    {
+      dir_path distribution; // debian, fedora, archive
+      dir_path os_release;   // fedora37, windows10
+      path     symlink;      // .../default, .../release
+      dir_path directory;    // .../default-2023-05-11T10:13:43Z
+
+      bool
+      operator< (const bindist_config& v)
+      {
+        if (int r = distribution.compare (v.distribution))
+          return   distribution.string () == "archive" ? false :
+                 v.distribution.string () == "archive" ? true  :
+                 r < 0;
+
+        if (int r = os_release.compare (v.os_release))
+          return r < 0;
+
+        return symlink < v.symlink;
+      }
+    };
+
+    vector<bindist_config> configs;
+
+    if (dir_exists (d))
+    try
+    {
+      for (const dir_entry& de: dir_iterator (d, dir_iterator::ignore_dangling))
+      {
+        if (de.type () != entry_type::directory)
+          continue;
+
+        // Distribution directory.
+        //
+        dir_path dd (path_cast<dir_path> (de.path ()));
+
+        try
+        {
+          dir_path fdd (d / dd);
+
+          for (const dir_entry& re:
+                 dir_iterator (fdd, dir_iterator::ignore_dangling))
+          {
+            if (re.type () != entry_type::directory)
+              continue;
+
+            // OS release directory.
+            //
+            dir_path rd (path_cast<dir_path> (re.path ()));
+
+            // Package version directory.
+            //
+            dir_path vd (fdd                               /
+                         rd                                /
+                         dir_path (pkg->project.string ()) /
+                         dir_path (pn.string ()) /
+                         dir_path (sver));
+
+            try
+            {
+              for (const dir_entry& ce:
+                     dir_iterator (vd, dir_iterator::ignore_dangling))
+              {
+                if (ce.ltype () != entry_type::symlink)
+                  continue;
+
+                // Skip symlinks which have extensions. Note that upload
+                // handlers may add an extension to a newly created symlink to
+                // atomically replace an old symlink with the new one.
+                //
+                const path& cl (ce.path ());
+                if (cl.extension_cstring () != nullptr)
+                  continue;
+
+                try
+                {
+                  path fcl (vd / cl);
+                  dir_path cd (path_cast<dir_path> (followsymlink (fcl)));
+
+                  if (cd.sub (br))
+                    configs.push_back (
+                      bindist_config {dd, rd, fcl.leaf (br), cd.leaf (br)});
+                }
+                catch (const system_error&) {}
+              }
+            }
+            catch (const system_error&) {}
+          }
+        }
+        catch (const system_error&) {}
+      }
+    }
+    catch (const system_error&) {}
+
+    // Sort and print collected package configurations, if any.
+    //
+    if (!configs.empty ())
+    {
+      sort (configs.begin (), configs.end ());
+
+      s << H3 << "Binaries" << ~H3
+        << TABLE(ID="binaries")
+        <<   TBODY;
+
+      for (const bindist_config& c: configs)
+      {
+        s << TR(CLASS="binaries")
+          <<   TD << SPAN(CLASS="value") << c.distribution << ~SPAN << ~TD
+          <<   TD << SPAN(CLASS="value") << c.os_release << ~SPAN << ~TD
+          <<   TD
+          <<     SPAN(CLASS="value")
+          <<       A
+          <<         HREF
+          <<           options_->bindist_url () << '/' << c.symlink
+          <<         ~HREF
+          <<         c.symlink.leaf ()
+          <<       ~A
+          <<       " ("
+          <<       A
+          <<         HREF
+          <<           options_->bindist_url () << '/' << c.directory
+          <<         ~HREF
+          <<         "snapshot"
+          <<       ~A
+          <<       ")"
+          <<     ~SPAN
+          <<   ~TD
+          << ~TR;
+      }
+
+      s <<   ~TBODY
+        << ~TABLE;
+    }
+  }
+
   if (builds)
   {
     s << H3 << "Builds" << ~H3
diff --git a/mod/mod-repository-root.cxx b/mod/mod-repository-root.cxx
index f00e80e..1b18996 100644
--- a/mod/mod-repository-root.cxx
+++ b/mod/mod-repository-root.cxx
@@ -16,6 +16,7 @@
 
 #include <mod/mod-ci.hxx>
 #include <mod/mod-submit.hxx>
+#include <mod/mod-upload.hxx>
 #include <mod/mod-builds.hxx>
 #include <mod/mod-packages.hxx>
 #include <mod/mod-build-log.hxx>
@@ -118,7 +119,8 @@ namespace brep
         builds_ (make_shared<builds> ()),
         build_configs_ (make_shared<build_configs> ()),
         submit_ (make_shared<submit> ()),
-        ci_ (make_shared<ci> ())
+        ci_ (make_shared<ci> ()),
+        upload_ (make_shared<upload> ())
   {
   }
 
@@ -178,6 +180,10 @@ namespace brep
           r.initialized_
           ? r.ci_
           : make_shared<ci> (*r.ci_)),
+        upload_ (
+          r.initialized_
+          ? r.upload_
+          : make_shared<upload> (*r.upload_)),
         options_ (
           r.initialized_
           ? r.options_
@@ -204,6 +210,7 @@ namespace brep
     append (r, build_configs_->options ());
     append (r, submit_->options ());
     append (r, ci_->options ());
+    append (r, upload_->options ());
     return r;
   }
 
@@ -249,6 +256,7 @@ namespace brep
     sub_init (*build_configs_, "build_configs");
     sub_init (*submit_, "submit");
     sub_init (*ci_, "ci");
+    sub_init (*upload_, "upload");
 
     // Parse own configuration options.
     //
@@ -444,6 +452,13 @@ namespace brep
 
           return handle ("ci", param);
         }
+        else if (func == "upload")
+        {
+          if (handler_ == nullptr)
+            handler_.reset (new upload (*upload_));
+
+          return handle ("upload", param);
+        }
         else
           return nullopt;
       };
diff --git a/mod/mod-repository-root.hxx b/mod/mod-repository-root.hxx
index 9e28797..4f40c94 100644
--- a/mod/mod-repository-root.hxx
+++ b/mod/mod-repository-root.hxx
@@ -24,6 +24,7 @@ namespace brep
   class build_configs;
   class submit;
   class ci;
+  class upload;
 
   class repository_root: public handler
   {
@@ -70,6 +71,7 @@ namespace brep
     shared_ptr<build_configs> build_configs_;
     shared_ptr<submit> submit_;
     shared_ptr<ci> ci_;
+    shared_ptr<upload> upload_;
 
     shared_ptr<options::repository_root> options_;
 
diff --git a/mod/mod-submit.cxx b/mod/mod-submit.cxx
index b73c96e..5ee358a 100644
--- a/mod/mod-submit.cxx
+++ b/mod/mod-submit.cxx
@@ -163,7 +163,7 @@ handle (request& rq, response& rs)
   if (!options_->submit_data_specified ())
     return respond_manifest (404, "submission disabled");
 
-  // Parse the request form data and verifying the submission size limit.
+  // Parse the request form data and verify the submission size limit.
   //
   // Note that if it is exceeded, then there are parameters and this is the
   // submission rather than the form request, and so we respond with the
@@ -292,8 +292,8 @@ handle (request& rq, response& rs)
     // However, using the abbreviated checksum can be helpful for
     // troubleshooting.
     //
-    td = dir_path (options_->submit_temp () /
-                   dir_path (path::traits_type::temp_name (ref)));
+    td = options_->submit_temp () /
+         dir_path (path::traits_type::temp_name (ref));
 
     // It's highly unlikely but still possible that the temporary directory
     // already exists. This can only happen due to the unclean web server
@@ -553,7 +553,7 @@ handle (request& rq, response& rs)
 
   // Run the submission handler, if specified, reading the result manifest
   // from its stdout and caching it as a name/value pair list for later use
-  // (forwarding to the client, sending via email, etc.). Otherwise, create
+  // (forwarding to the client, sending via email, etc). Otherwise, create
   // implied result manifest.
   //
   status_code sc;
diff --git a/mod/mod-upload.cxx b/mod/mod-upload.cxx
new file mode 100644
index 0000000..1474363
--- /dev/null
+++ b/mod/mod-upload.cxx
@@ -0,0 +1,766 @@
+// file      : mod/mod-upload.cxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#include <mod/mod-upload.hxx>
+
+#include <odb/database.hxx>
+#include <odb/transaction.hxx>
+
+#include <libbutl/uuid.hxx>
+#include <libbutl/base64.hxx>
+#include <libbutl/sha256.hxx>
+#include <libbutl/sendmail.hxx>
+#include <libbutl/fdstream.hxx>
+#include <libbutl/timestamp.hxx>
+#include <libbutl/filesystem.hxx>
+#include <libbutl/process-io.hxx>          // operator<<(ostream, process_args)
+#include <libbutl/manifest-types.hxx>
+#include <libbutl/manifest-serializer.hxx>
+
+#include <web/server/module.hxx>
+
+#include <libbrep/build.hxx>
+#include <libbrep/build-odb.hxx>
+#include <libbrep/build-package.hxx>
+#include <libbrep/build-package-odb.hxx>
+
+#include <mod/module-options.hxx>
+#include <mod/external-handler.hxx>
+
+using namespace std;
+using namespace butl;
+using namespace brep::cli;
+using namespace odb::core;
+
+// While currently the user-defined copy constructor is not required (we don't
+// need to deep copy nullptr's), it is a good idea to keep the placeholder
+// ready for less trivial cases.
+//
+brep::upload::
+upload (const upload& r)
+    : build_result_module (r),
+      options_ (r.initialized_ ? r.options_  : nullptr)
+{
+}
+
+void brep::upload::
+init (scanner& s)
+{
+  HANDLER_DIAG;
+
+  options_ = make_shared<options::upload> (
+    s, unknown_mode::fail, unknown_mode::fail);
+
+  // Verify that the upload handling is setup properly, if configured.
+  //
+  for (const auto& ud: options_->upload_data ())
+  {
+    const string& t (ud.first);
+
+    if (t.empty ())
+      fail << "empty upload type in upload-data configuration option";
+
+    if (ud.second.relative ())
+      fail << t << " upload-data path '" << ud.second << "' is relative";
+
+    if (!dir_exists (ud.second))
+      fail << t << " upload-data directory '" << ud.second
+           << "' does not exist";
+
+    const map<string, path>& uh (options_->upload_handler ());
+    auto i (uh.find (t));
+
+    if (i != uh.end () && i->second.relative ())
+      fail << t << " upload-handler path '" << i->second << "' is relative";
+  }
+
+  if (options_->upload_data_specified ())
+  {
+    if (!options_->build_config_specified ())
+      fail << "upload functionality is enabled but package building "
+           << "functionality is disabled";
+
+    build_result_module::init (*options_, *options_);
+  }
+
+  if (options_->root ().empty ())
+    options_->root (dir_path ("/"));
+}
+
+bool brep::upload::
+handle (request& rq, response& rs)
+{
+  using brep::version; // Not to confuse with module::version.
+
+  using serializer    = manifest_serializer;
+  using serialization = manifest_serialization;
+
+  HANDLER_DIAG;
+
+  // We will respond with the manifest to the upload protocol violations and
+  // with a plain text message on the internal errors. In the latter case we
+  // will always respond with the same neutral message for security reason,
+  // logging the error details. Note that descriptions of exceptions caught by
+  // the web server are returned to the client (see web/module.hxx for
+  // details), and we want to avoid this when there is a danger of exposing
+  // sensitive data.
+  //
+  // Also we will pass through exceptions thrown by the underlying API, unless
+  // we need to handle them or add details for the description, in which case
+  // we will fallback to one of the above mentioned response methods.
+  //
+  // Note that both respond_manifest() and respond_error() are normally called
+  // right before the end of the request handling. They both always return
+  // true to allow bailing out with a single line, for example:
+  //
+  // return respond_error (); // Request is handled with an error.
+  //
+  string request_id; // Will be set later.
+  auto respond_manifest = [&rs, &request_id] (status_code status,
+                                              const string& message) -> bool
+  {
+    serializer s (rs.content (status, "text/manifest;charset=utf-8"),
+                  "response");
+
+    s.next ("", "1");                      // Start of manifest.
+    s.next ("status", to_string (status));
+    s.next ("message", message);
+
+    if (!request_id.empty ())
+      s.next ("reference", request_id);
+
+    s.next ("", ""); // End of manifest.
+    return true;
+  };
+
+  auto respond_error = [&rs] (status_code status = 500) -> bool
+  {
+    rs.content (status, "text/plain;charset=utf-8")
+      << "upload handling failed" << endl;
+
+    return true;
+  };
+
+  // Check if the upload functionality is enabled.
+  //
+  // Note that this is not an upload protocol violation but it feels right to
+  // respond with the manifest, to help the client a bit.
+  //
+  if (!options_->upload_data_specified ())
+    return respond_manifest (404, "upload disabled");
+
+  // Parse the request data and verify the upload size limit.
+  //
+  // Note that the size limit is upload type-specific. Thus, first, we need to
+  // determine the upload type which we expect to be specified in the URL as a
+  // value of the upload parameter.
+  //
+  string type;
+  dir_path dir;
+
+  try
+  {
+    name_value_scanner s (rq.parameters (0 /* limit */, true /* url_only */));
+
+    // We only expect the upload=<type> parameter in URL.
+    //
+    params::upload params (
+      params::upload (s, unknown_mode::fail, unknown_mode::fail));
+
+    type = move (params.type ());
+
+    if (type.empty ())
+      return respond_manifest (400, "upload type expected");
+
+    // Check if this upload type is enabled. While at it, cache the upload
+    // data directory path.
+    //
+    const map<string, dir_path>& ud (options_->upload_data ());
+    auto i (ud.find (type));
+
+    if (i == ud.end ())
+      return respond_manifest (404, type + " upload disabled");
+
+    dir = i->second;
+  }
+  catch (const cli::exception&)
+  {
+    return respond_manifest (400, "invalid parameter");
+  }
+
+  try
+  {
+    const map<string, size_t>& us (options_->upload_max_size ());
+    auto i (us.find (type));
+    rq.parameters (i != us.end () ? i->second : 10485760); // 10M by default.
+  }
+  catch (const invalid_request& e)
+  {
+    if (e.status == 413) // Payload too large?
+      return respond_manifest (e.status, type + " upload size exceeds limit");
+
+    throw;
+  }
+
+  // The request parameters are now parsed and the limit doesn't really matter.
+  //
+  const name_values& rps (rq.parameters (0 /* limit */));
+
+  // Verify the upload parameters we expect. The unknown ones will be
+  // serialized to the upload manifest.
+  //
+  params::upload params;
+
+  try
+  {
+    name_value_scanner s (rps);
+    params = params::upload (s, unknown_mode::skip, unknown_mode::skip);
+  }
+  catch (const cli::exception&)
+  {
+    return respond_manifest (400, "invalid parameter");
+  }
+
+  const string& session   (params.session ());
+  const string& instance  (params.instance ());
+  const string& archive   (params.archive ());
+  const string& sha256sum (params.sha256sum ());
+
+  if (session.empty ())
+    return respond_manifest (400, "upload session expected");
+
+  optional<vector<char>> challenge;
+
+  if (params.challenge_specified ())
+  try
+  {
+    challenge = base64_decode (params.challenge ());
+  }
+  catch (const invalid_argument&)
+  {
+    return respond_manifest (400, "invalid challenge");
+  }
+
+  if (instance.empty ())
+    return respond_manifest (400, "upload instance expected");
+
+  if (archive.empty ())
+    return respond_manifest (400, "upload archive expected");
+
+  if (sha256sum.empty ())
+    return respond_manifest (400, "upload archive checksum expected");
+
+  if (sha256sum.size () != 64)
+    return respond_manifest (400, "invalid upload archive checksum");
+
+  // Verify that unknown parameter values satisfy the requirements (contain
+  // only UTF-8 encoded graphic characters plus '\t', '\r', and '\n').
+  //
+  // Actually, the expected ones must satisfy too, so check them as well.
+  //
+  string what;
+  for (const name_value& nv: rps)
+  {
+    if (nv.value &&
+        !utf8 (*nv.value, what, codepoint_types::graphic, U"\n\r\t"))
+      return respond_manifest (400,
+                               "invalid parameter " + nv.name + ": " + what);
+  }
+
+  parse_session_result sess;
+
+  try
+  {
+    sess = parse_session (session);
+  }
+  catch (const invalid_argument& e)
+  {
+    return respond_manifest (400, string ("invalid session: ") + e.what ());
+  }
+
+  // If the session expired (no such configuration, etc) then, similar to the
+  // build result module, we log this case with the warning severity and
+  // respond with manifest with the 200 status as if the session is valid (see
+  // the build result module for the reasoning).
+  //
+  auto warn_expired = [&session, &warn] (const string& d)
+  {
+    warn << "session '" << session << "' expired: " << d;
+  };
+
+  const build_id& id (sess.id);
+
+  // Make sure the build configuration still exists.
+  //
+  const build_target_config* tc;
+  {
+    auto i (target_conf_map_->find (
+              build_target_config_id {id.target, id.target_config_name}));
+
+    if (i == target_conf_map_->end ())
+    {
+      warn_expired ("no build configuration");
+      return respond_manifest (200, type + " upload is queued");
+    }
+
+    tc = i->second;
+  }
+
+  // Note that if the session authentication fails (probably due to the
+  // authentication settings change), then we log this case with the warning
+  // severity and respond with manifest with the 200 status as if the
+  // challenge is valid (see the build result module for the reasoning).
+  //
+  shared_ptr<build> bld;
+  shared_ptr<build_package> pkg;
+  shared_ptr<build_repository> rep;
+  {
+    transaction t (build_db_->begin ());
+
+    package_build pb;
+    shared_ptr<build> b;
+    if (!build_db_->query_one<package_build> (
+          query<package_build>::build::id == id, pb))
+    {
+      warn_expired ("no package build");
+    }
+    else if ((b = move (pb.build))->state != build_state::building)
+    {
+      warn_expired ("package configuration state is " + to_string (b->state));
+    }
+    else if (b->timestamp != sess.timestamp)
+    {
+      warn_expired ("non-matching timestamp");
+    }
+    else if (authenticate_session (*options_, challenge, *b, session))
+    {
+      bld = move (b);
+      pkg = build_db_->load<build_package> (id.package);
+      rep = pkg->internal_repository.load ();
+    }
+
+    t.commit ();
+  }
+
+  // Note that from now on the result manifest we respond with will contain
+  // the reference value.
+  //
+  try
+  {
+    request_id = uuid::generate ().string ();
+  }
+  catch (const system_error& e)
+  {
+    error << "unable to generate request id: " << e;
+    return respond_error ();
+  }
+
+  if (bld == nullptr)
+    return respond_manifest (200, type + " upload is queued");
+
+  // Create the upload data directory.
+  //
+  dir_path dd (dir / dir_path (request_id));
+
+  try
+  {
+    // It's highly unlikely but still possible that the directory already
+    // exists. This can only happen if the generated uuid is not unique.
+    //
+    if (try_mkdir (dd) == mkdir_status::already_exists)
+      throw_generic_error (EEXIST);
+  }
+  catch (const system_error& e)
+  {
+    error << "unable to create directory '" << dd << "': " << e;
+    return respond_error ();
+  }
+
+  auto_rmdir ddr (dd);
+
+  // Save the package archive into the temporary directory and verify its
+  // checksum.
+  //
+  // Note that the archive file name can potentially contain directory path in
+  // the POSIX form, so let's strip it if that's the case.
+  //
+  path a;
+  path af;
+
+  try
+  {
+    size_t n (archive.find_last_of ('/'));
+    a = path (n != string::npos ? string (archive, n + 1) : archive);
+    af = dd / a;
+  }
+  catch (const invalid_path&)
+  {
+    return respond_manifest (400, "invalid package archive name");
+  }
+
+  try
+  {
+    istream& is (rq.open_upload ("archive"));
+
+    // Note that istream::read() sets failbit if unable to read the requested
+    // number of bytes.
+    //
+    is.exceptions (istream::badbit);
+
+    sha256 sha;
+    char buf[8192];
+    ofdstream os (af, fdopen_mode::binary);
+
+    while (!eof (is))
+    {
+      is.read (buf, sizeof (buf));
+
+      if (size_t n = is.gcount ())
+      {
+        sha.append (buf, n);
+        os.write (buf, n);
+      }
+    }
+
+    os.close ();
+
+    // Respond with the unprocessable entity (422) code for the archive
+    // checksum mismatch.
+    //
+    if (sha.string () != sha256sum)
+      return respond_manifest (422, "upload archive checksum mismatch");
+  }
+  // Note that invalid_argument (thrown by open_upload() function call) can
+  // mean both no archive upload or multiple archive uploads.
+  //
+  catch (const invalid_argument&)
+  {
+    return respond_manifest (400, "archive upload expected");
+  }
+  catch (const io_error& e)
+  {
+    error << "unable to write package archive '" << af << "': " << e;
+    return respond_error ();
+  }
+
+  // Serialize the upload request manifest to a stream. On the serialization
+  // error respond to the client with the manifest containing the bad request
+  // (400) code and return false, on the stream error pass through the
+  // io_error exception, otherwise return true.
+  //
+  timestamp ts (system_clock::now ());
+
+  auto rqm = [&request_id,
+              &ts,
+              &rps,
+              &session,
+              &instance,
+              &a,
+              &sha256sum,
+              &id,
+              &bld,
+              &pkg,
+              &rep,
+              &tc,
+              &sess,
+              &respond_manifest,
+              this] (ostream& os, bool long_lines = false) -> bool
+  {
+    try
+    {
+      serializer s (os, "request", long_lines);
+
+      // Serialize the upload manifest header.
+      //
+      s.next ("", "1");                // Start of manifest.
+      s.next ("id", request_id);
+      s.next ("session", session);
+      s.next ("instance", instance);
+      s.next ("archive", a.string ());
+      s.next ("sha256sum", sha256sum);
+
+      s.next ("timestamp",
+              butl::to_string (ts,
+                               "%Y-%m-%dT%H:%M:%SZ",
+                               false /* special */,
+                               false /* local */));
+
+      s.next ("name", id.package.name.string ());
+      s.next ("version", pkg->version.string ());
+      s.next ("project", pkg->project.string ());
+      s.next ("target-config", tc->name);
+      s.next ("package-config", id.package_config_name);
+      s.next ("target", tc->target.string ());
+
+      if (!tenant.empty ())
+        s.next ("tenant", tenant);
+
+      s.next ("toolchain-name", id.toolchain_name);
+      s.next ("toolchain-version", sess.toolchain_version.string ());
+      s.next ("repository-name", rep->canonical_name);
+
+      s.next ("machine-name", bld->machine);
+      s.next ("machine-summary", bld->machine_summary);
+
+      // Serialize the request parameters.
+      //
+      // Note that the serializer constraints the parameter names (can't start
+      // with '#', can't contain ':' and the whitespaces, etc.).
+      //
+      for (const name_value& nv: rps)
+      {
+        // Note that the upload parameter is renamed to '_' by the root
+        // handler (see the request_proxy class for details).
+        //
+        const string& n (nv.name);
+        if (n != "_"         &&
+            n != "session"   &&
+            n != "challenge" &&
+            n != "instance"  &&
+            n != "archive"   &&
+            n != "sha256sum")
+          s.next (n, nv.value ? *nv.value : "");
+      }
+
+      s.next ("", ""); // End of manifest.
+      return true;
+    }
+    catch (const serialization& e)
+    {
+      respond_manifest (400, string ("invalid parameter: ") + e.what ());
+      return false;
+    }
+  };
+
+  // Serialize the upload request manifest to the upload directory.
+  //
+  path rqf (dd / "request.manifest");
+
+  try
+  {
+    ofdstream os (rqf);
+    bool r (rqm (os));
+    os.close ();
+
+    if (!r)
+      return true; // The client is already responded with the manifest.
+  }
+  catch (const io_error& e)
+  {
+    error << "unable to write to '" << rqf << "': " << e;
+    return respond_error ();
+  }
+
+  // Given that the upload data is now successfully persisted we are no longer
+  // in charge of removing it, except for the cases when the upload
+  // handler terminates with an error (see below for details).
+  //
+  ddr.cancel ();
+
+  // If the handler terminates with non-zero exit status or specifies 5XX
+  // (HTTP server error) upload result manifest status value, then we stash
+  // the upload data directory for troubleshooting. Otherwise, if it's the 4XX
+  // (HTTP client error) status value, then we remove the directory.
+  //
+  auto stash_upload_dir = [&dd, error] ()
+  {
+    if (dir_exists (dd))
+    try
+    {
+      mvdir (dd, dir_path (dd + ".fail"));
+    }
+    catch (const system_error& e)
+    {
+      // Not much we can do here. Let's just log the issue and bail out
+      // leaving the directory in place.
+      //
+      error << "unable to rename directory '" << dd << "': " << e;
+    }
+  };
+
+  // Run the upload handler, if specified, reading the result manifest from
+  // its stdout and caching it as a name/value pair list for later use
+  // (forwarding to the client, sending via email, etc). Otherwise, create
+  // implied result manifest.
+  //
+  status_code sc;
+  vector<manifest_name_value> rvs;
+
+  const map<string, path>& uh (options_->upload_handler ());
+  auto hi (uh.find (type));
+
+  if (hi != uh.end ())
+  {
+    auto range (options_->upload_handler_argument ().equal_range (type));
+
+    strings args;
+    for (auto i (range.first); i != range.second; ++i)
+      args.push_back (i->second);
+
+    const map<string, size_t>& ht (options_->upload_handler_timeout ());
+    auto i (ht.find (type));
+
+    optional<external_handler::result_manifest> r (
+      external_handler::run (hi->second,
+                             args,
+                             dd,
+                             i != ht.end () ? i->second : 0,
+                             error,
+                             warn,
+                             verb_ ? &trace : nullptr));
+
+    if (!r)
+    {
+      stash_upload_dir ();
+      return respond_error (); // The diagnostics is already issued.
+    }
+
+    sc = r->status;
+    rvs = move (r->values);
+  }
+  else // Create the implied result manifest.
+  {
+    sc = 200;
+
+    auto add = [&rvs] (string n, string v)
+    {
+      manifest_name_value nv {
+        move (n), move (v),
+        0 /* name_line */,  0 /* name_column */,
+        0 /* value_line */, 0 /* value_column */,
+        0 /* start_pos */, 0 /* colon_pos */, 0 /* end_pos */};
+
+      rvs.emplace_back (move (nv));
+    };
+
+    add ("status", "200");
+    add ("message", type + " upload is queued");
+    add ("reference", request_id);
+  }
+
+  assert (!rvs.empty ()); // Produced by the handler or is implied.
+
+  // Serialize the upload result manifest to a stream. On the serialization
+  // error log the error description and return false, on the stream error
+  // pass through the io_error exception, otherwise return true.
+  //
+  auto rsm = [&rvs,
+              &error,
+              &request_id,
+              &type] (ostream& os, bool long_lines = false) -> bool
+  {
+    try
+    {
+      serializer s (os, "result", long_lines);
+      serialize_manifest (s, rvs);
+      return true;
+    }
+    catch (const serialization& e)
+    {
+      error << "ref " << request_id << ": unable to serialize " << type
+            << " upload handler's output: " << e;
+      return false;
+    }
+  };
+
+  // If the upload data directory still exists then perform an appropriate
+  // action on it, depending on the upload result status. Note that the
+  // handler could move or remove the directory.
+  //
+  if (dir_exists (dd))
+  {
+    // Remove the directory if the client error is detected.
+    //
+    if (sc >= 400 && sc < 500)
+    {
+      rmdir_r (dd);
+    }
+    //
+    // Otherwise, save the result manifest, into the directory. Also stash the
+    // directory for troubleshooting in case of the server error.
+    //
+    else
+    {
+      path rsf (dd / "result.manifest");
+
+      try
+      {
+        ofdstream os (rsf);
+
+        // Not being able to stash the result manifest is not a reason to
+        // claim the upload failed. The error is logged nevertheless.
+        //
+        rsm (os);
+
+        os.close ();
+      }
+      catch (const io_error& e)
+      {
+        // Not fatal (see above).
+        //
+        error << "unable to write to '" << rsf << "': " << e;
+      }
+
+      if (sc >= 500 && sc < 600)
+        stash_upload_dir ();
+    }
+  }
+
+  // Send email, if configured. Use the long lines manifest serialization mode
+  // for the convenience of copying/clicking URLs they contain.
+  //
+  // Note that we don't consider the email sending failure to be an upload
+  // failure as the upload data is successfully persisted and the handler is
+  // successfully executed, if configured. One can argue that email can be
+  // essential for the upload processing and missing it would result in the
+  // incomplete upload. In this case it's natural to assume that the web
+  // server error log is monitored and the email sending failure will be
+  // noticed.
+  //
+  const map<string, string>& ue (options_->upload_email ());
+  auto ei (ue.find (type));
+
+  if (ei != ue.end ())
+  try
+  {
+    // Redirect the diagnostics to the web server error log.
+    //
+    sendmail sm ([&trace, this] (const char* args[], size_t n)
+                 {
+                   l2 ([&]{trace << process_args {args, n};});
+                 },
+                 2 /* stderr */,
+                 options_->email (),
+                 type + " upload (" + request_id + ')',
+                 {ei->second});
+
+    // Write the upload request manifest.
+    //
+    bool r (rqm (sm.out, true /* long_lines */));
+    assert (r); // The serialization succeeded once, so can't fail now.
+
+    // Write the upload result manifest.
+    //
+    sm.out << "\n\n";
+
+    // We don't care about the result (see above).
+    //
+    rsm (sm.out, true /* long_lines */);
+
+    sm.out.close ();
+
+    if (!sm.wait ())
+      error << "sendmail " << *sm.exit;
+  }
+  // Handle process_error and io_error (both derive from system_error).
+  //
+  catch (const system_error& e)
+  {
+    error << "sendmail error: " << e;
+  }
+
+  if (!rsm (rs.content (sc, "text/manifest;charset=utf-8")))
+    return respond_error (); // The error description is already logged.
+
+  return true;
+}
diff --git a/mod/mod-upload.hxx b/mod/mod-upload.hxx
new file mode 100644
index 0000000..6cc723b
--- /dev/null
+++ b/mod/mod-upload.hxx
@@ -0,0 +1,41 @@
+// file      : mod/mod-upload.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef MOD_MOD_UPLOAD_HXX
+#define MOD_MOD_UPLOAD_HXX
+
+#include <libbrep/types.hxx>
+#include <libbrep/utility.hxx>
+
+#include <mod/module-options.hxx>
+#include <mod/build-result-module.hxx>
+
+namespace brep
+{
+  class upload: public build_result_module
+  {
+  public:
+    upload () = default;
+
+    // Create a shallow copy (handling instance) if initialized and a deep
+    // copy (context exemplar) otherwise.
+    //
+    explicit
+    upload (const upload&);
+
+    virtual bool
+    handle (request&, response&);
+
+    virtual const cli::options&
+    cli_options () const {return options::upload::description ();}
+
+  private:
+    virtual void
+    init (cli::scanner&);
+
+  private:
+    shared_ptr<options::upload> options_;
+  };
+}
+
+#endif // MOD_MOD_UPLOAD_HXX
diff --git a/mod/module.cli b/mod/module.cli
index 3d4ea00..4c10826 100644
--- a/mod/module.cli
+++ b/mod/module.cli
@@ -343,6 +343,82 @@ namespace brep
       }
     };
 
+    class build_upload
+    {
+      std::map<string, dir_path> upload-data
+      {
+        "<type>=<dir>",
+        "The directory to save upload data to for the specified upload type.
+         If unspecified, the build artifacts upload functionality will be
+         disabled for this type. See \l{brep The \cb{build2} Repository
+         Interface Manual} for more information on build artifacts upload.
+
+         Note that the directory path must be absolute and the directory
+         itself must exist and have read, write, and execute permissions
+         granted to the user that runs the web server."
+      }
+
+      std::map<string, size_t> upload-max-size
+      {
+        "<type>=<bytes>",
+        "The maximum size of the upload data accepted for the specified upload
+         type. Note that currently the entire upload request is read into
+         memory. The default is 10M."
+      }
+
+      std::map<string, string> upload-email
+      {
+        "<type>=<email>",
+        "The build artifacts upload email. If specified, the upload request
+         and result manifests will be sent to this address. See \l{brep The
+         \cb{build2} Repository Interface Manual} for more information."
+      }
+
+      std::map<string, path> upload-handler
+      {
+        "<type>=<path>",
+        "The handler program to be executed on build artifacts upload of the
+         specified type. The handler is executed as part of the HTTP request
+         and is passed additional arguments that can be specified with
+         \cb{upload-handler-argument} followed by the absolute path to the
+         upload directory (\cb{upload-data}). See \l{brep The \cb{build2}
+         Repository Interface Manual} for more information. Note that the
+         program path must be absolute."
+      }
+
+      std::multimap<string, string> upload-handler-argument
+      {
+        "<type>=<arg>",
+        "Additional arguments to be passed to the upload handler program for
+         the specified upload type (see \cb{upload-handler} for details).
+         Repeat this option to specify multiple arguments."
+      }
+
+      std::map<string, size_t> upload-handler-timeout
+      {
+        "<type>=<seconds>",
+        "The upload handler program timeout in seconds for the specified
+         upload type. If specified and the handler does not exit in the
+         allotted time, then it is killed and its termination is treated as
+         abnormal."
+      }
+
+      std::multimap<string, string> upload-toolchain-exclude
+      {
+        "<type>=<name>",
+        "Disable upload of the specified type for the specified toolchain
+         name. Repeat this option to disable uploads for multiple toolchains."
+      }
+
+      std::multimap<string, string> upload-repository-exclude
+      {
+        "<type>=<name>",
+        "Disable upload of the specified type for packages from the repository
+         with the specified canonical name. Repeat this option to disable
+         uploads for multiple repositories."
+      }
+    };
+
     class page
     {
       web::xhtml::fragment logo
@@ -416,13 +492,36 @@ namespace brep
                                    page,
                                    handler
     {
+      dir_path bindist-root
+      {
+        "<dir>",
+        "The root directory where the uploaded binary distribution packages
+         are saved to under the following directory hierarchy:
+
+         \
+         [<tenant>/]<distribution>/<os-release>/<project>/<package>/<version>/<package-config>
+         \
+
+         The package configuration directory symlinks that match these paths
+         are mapped to web URLs based on the \cb{bindist-url} value and
+         displayed on the package version details page. If this option is
+         specified, then \cb{bindist-url} must be specified as well."
+      }
+
+      string bindist-url
+      {
+        "<url>",
+        "The root URL of the directory specified with the \cb{bindist-root}
+         option. This option must be specified if \cb{bindist-root} is
+         specified."
+      }
     };
 
     class repository_details: package_db, page, handler
     {
     };
 
-    class build_task: build, build_db, handler
+    class build_task: build, build_db, build_upload, handler
     {
       size_t build-task-request-max-size = 102400
       {
@@ -666,6 +765,10 @@ namespace brep
       }
     };
 
+    class upload: build, build_db, build_upload, handler
+    {
+    };
+
     class repository_root: handler
     {
       string root-global-view = "packages"
@@ -930,5 +1033,45 @@ namespace brep
       //
       string simulate;
     };
+
+    // Parameters other than challenge must be all present.
+    //
+    // Note also that besides these parameters there can be others. We don't
+    // recognize their semantics and just save them to the upload request
+    // manifest.
+    //
+    class upload
+    {
+      // Upload type.
+      //
+      // Note that the upload parameter is renamed to '_' by the root handler
+      // (see the request_proxy class for details).
+      //
+      string type | _;
+
+      // Session id as returned by brep in the task response.
+      //
+      string session;
+
+      // Answer to the private key challenge as posed by brep in the task
+      // response. It must be present only if the challenge value was present
+      // in the task response.
+      //
+      string challenge;
+
+      // Upload instance name.
+      //
+      string instance;
+
+      // Package archive file name. Must be <input type="file"/>.
+      //
+      // Note that it can potentially be not just a name but a file path.
+      //
+      string archive;
+
+      // Package archive file SHA256 checksum.
+      //
+      string sha256sum;
+    };
   }
 }