Add the ignore_mdc_error flag setter and getter

.gitignore

@@ -6,3 +6,4 @@ coverage
 Gemfile.lock
 /tmp/*
 /ports/*
+.byebug_history

ext/gpgme/gpgme_n.c

@@ -514,6 +514,46 @@ rb_s_gpgme_release (VALUE dummy, VALUE vctx)
   return Qnil;
 }
 
+static VALUE
+rb_s_gpgme_set_ctx_flag (VALUE dummy, VALUE vctx, VALUE vname, VALUE vstr)
+{
+  gpgme_ctx_t ctx;
+  gpgme_error_t err;
+  char* name;
+  char* str;
+
+  name = StringValueCStr(vname);
+  str = StringValueCStr(vstr);
+
+  UNWRAP_GPGME_CTX(vctx, ctx);
+  if (!ctx)
+    rb_raise (rb_eArgError, "released ctx");
+
+  err = gpgme_set_ctx_flag(ctx, name, str);
+  return LONG2NUM(err);
+}
+
+static VALUE
+rb_s_gpgme_get_ctx_flag (VALUE dummy, VALUE vctx, VALUE vname)
+{
+  gpgme_ctx_t ctx;
+  const char* name;
+  int yes;
+
+  name = StringValueCStr(vname);
+
+  UNWRAP_GPGME_CTX(vctx, ctx);
+  if (!ctx)
+    rb_raise (rb_eArgError, "released ctx");
+
+  const char* result;
+  result = gpgme_get_ctx_flag(ctx, name);
+  if (result == NULL)
+    rb_raise (rb_eArgError, "incorrect ctx flag name");
+
+  return rb_str_new_cstr(result);
+}
+
 static VALUE
 rb_s_gpgme_set_protocol (VALUE dummy, VALUE vctx, VALUE vproto)
 {
@@ -566,6 +606,42 @@ rb_s_gpgme_get_armor (VALUE dummy, VALUE vctx)
   return INT2FIX(yes);
 }
 
+static VALUE
+rb_s_gpgme_set_ignore_mdc_error (VALUE dummy, VALUE vctx, VALUE vyes)
+{
+  gpgme_ctx_t ctx;
+  gpgme_error_t err;
+  int yes;
+
+  yes = NUM2INT(vyes);
+
+  UNWRAP_GPGME_CTX(vctx, ctx);
+  if (!ctx)
+    rb_raise (rb_eArgError, "released ctx");
+
+  err = gpgme_set_ctx_flag(ctx, "ignore-mdc-error", yes ? "1" : "");
+  return LONG2NUM(err);
+}
+
+static VALUE
+rb_s_gpgme_get_ignore_mdc_error (VALUE dummy, VALUE vctx)
+{
+  gpgme_ctx_t ctx;
+  int yes;
+
+  UNWRAP_GPGME_CTX(vctx, ctx);
+  if (!ctx)
+    rb_raise (rb_eArgError, "released ctx");
+
+  const char* result;
+  result = gpgme_get_ctx_flag(ctx, "ignore-mdc-error");
+  if (result == NULL)
+    rb_raise (rb_eArgError, "incorrect ctx flag name");
+
+  yes = (result && *result)? !!atoi (result) : 0;
+  return INT2FIX(yes);
+}
+
 static VALUE
 rb_s_gpgme_set_textmode (VALUE dummy, VALUE vctx, VALUE vyes)
 {
@@ -2373,6 +2449,10 @@ Init_gpgme_n (void)
                              rb_s_gpgme_release, 1);
 
   /* Context Attributes */
+  rb_define_module_function (mGPGME, "gpgme_set_ctx_flag",
+                             rb_s_gpgme_set_ctx_flag, 3);
+  rb_define_module_function (mGPGME, "gpgme_get_ctx_flag",
+                             rb_s_gpgme_get_ctx_flag, 2);
   rb_define_module_function (mGPGME, "gpgme_set_protocol",
                              rb_s_gpgme_set_protocol, 2);
   rb_define_module_function (mGPGME, "gpgme_get_protocol",
@@ -2381,6 +2461,10 @@ Init_gpgme_n (void)
                              rb_s_gpgme_set_armor, 2);
   rb_define_module_function (mGPGME, "gpgme_get_armor",
                              rb_s_gpgme_get_armor, 1);
+  rb_define_module_function (mGPGME, "gpgme_set_ignore_mdc_error",
+                             rb_s_gpgme_set_ignore_mdc_error, 2);
+  rb_define_module_function (mGPGME, "gpgme_get_ignore_mdc_error",
+                             rb_s_gpgme_get_ignore_mdc_error, 1);
   rb_define_module_function (mGPGME, "gpgme_set_textmode",
                              rb_s_gpgme_set_textmode, 2);
   rb_define_module_function (mGPGME, "gpgme_get_textmode",

lib/gpgme/ctx.rb

@@ -49,12 +49,13 @@ def self.new(options = {})
       raise exc if exc
       ctx = rctx[0]
 
-      ctx.protocol      = options[:protocol]      if options[:protocol]
-      ctx.armor         = options[:armor]         if options[:armor]
-      ctx.textmode      = options[:textmode]      if options[:textmode]
-      ctx.keylist_mode  = options[:keylist_mode]  if options[:keylist_mode]
-      ctx.pinentry_mode = options[:pinentry_mode] if options[:pinentry_mode]
-      ctx.offline       = options[:offline]       if options[:offline]
+      ctx.protocol          = options[:protocol]          if options[:protocol]
+      ctx.armor             = options[:armor]             if options[:armor]
+      ctx.textmode          = options[:textmode]          if options[:textmode]
+      ctx.keylist_mode      = options[:keylist_mode]      if options[:keylist_mode]
+      ctx.pinentry_mode     = options[:pinentry_mode]     if options[:pinentry_mode]
+      ctx.offline           = options[:offline]           if options[:offline]
+      ctx.ignore_mdc_error  = options[:ignore_mdc_error]  if options[:ignore_mdc_error]
 
       if options[:password]
         ctx.set_passphrase_callback GPGME::Ctx.method(:pass_function),
@@ -103,6 +104,43 @@ def release
     # Getters and setters
     ##
 
+    # Get the value of the Ctx flag with the given name.
+    #
+    # Allowed flag names may include:
+    # - 'redraw'
+    # - 'full-status'
+    # - 'raw-description'
+    # - 'export-session-key'
+    # - 'override-session-key'
+    # - 'include-key-block'
+    # - 'auto-key-import'
+    # - 'auto-key-retrieve'
+    # - 'request-origin'
+    # - 'no-symkey-cache'
+    # - 'ignore-mdc-error'
+    # - 'auto-key-locate'
+    # - 'trust-model'
+    # - 'extended-edit'
+    # - 'cert-expire'
+    # - 'key-origin'
+    # - 'import-filter'
+    # - 'no-auto-check-trustdb'
+    #
+    # Please consult the GPGPME documentation for more details
+    #
+    def get_ctx_flag(flag_name)
+      GPGME::gpgme_get_ctx_flag(self, flag_name.to_s)
+    end
+
+    # Set the Ctx flag with the given name
+    # to the given value.
+    def set_ctx_flag(flag_name, val)
+      err = GPGME::gpgme_set_ctx_flag(self, flag_name.to_s, val.to_s)
+      exc = GPGME::error_to_exception(err)
+      raise exc if exc
+      val
+    end
+
     # Set the +protocol+ used within this context. See {GPGME::Ctx.new} for
     # possible values.
     def protocol=(proto)
@@ -128,6 +166,22 @@ def armor
       GPGME::gpgme_get_armor(self) == 1 ? true : false
     end
 
+    # This option ignores a MDC integrity protection failure.
+    # It is required to decrypt old messages which did not use an MDC.
+    # It may also be useful if a message is partially garbled,
+    # but it is necessary to get as much data as possible out of that garbled message.
+    # Be aware that a missing or failed MDC can be an indication of an attack.
+    # Use with great caution.
+    def ignore_mdc_error=(yes)
+      GPGME::gpgme_set_ignore_mdc_error(self, yes ? 1 : 0)
+      yes
+    end
+
+    # Return true if the MDC integrity protection is disabled.
+    def ignore_mdc_error
+      GPGME::gpgme_get_ignore_mdc_error(self) == 1 ? true : false
+    end
+
     # Tell whether canonical text mode should be used.
     def textmode=(yes)
       GPGME::gpgme_set_textmode(self, yes ? 1 : 0)

test/ctx_test.rb

@@ -81,6 +81,70 @@
     end
   end
 
+  describe :get_ctx_flag do
+    it "reads flags with getters and setters" do
+      ctx = GPGME::Ctx.new
+
+      refute ctx.ignore_mdc_error
+      assert_equal "", ctx.get_ctx_flag("ignore-mdc-error")
+
+      ctx.ignore_mdc_error = true
+
+      assert ctx.ignore_mdc_error
+      assert_equal "1", ctx.get_ctx_flag("ignore-mdc-error")
+    end
+
+    it "can get flags without getters and setters" do
+      ctx = GPGME::Ctx.new
+
+      assert_equal "", ctx.get_ctx_flag("auto-key-locate")
+      ctx.set_ctx_flag("auto-key-locate", "cert")
+      assert_equal "cert", ctx.get_ctx_flag("auto-key-locate")
+    end
+
+    it "raises an error when a flag doesn't exist" do
+      ctx = GPGME::Ctx.new
+
+      assert_raises ArgumentError do
+        ctx.get_ctx_flag("foo")
+      end
+    end
+  end
+
+  describe :set_ctx_flag do
+    it "sets the value for a flag with a getter" do
+      ctx = GPGME::Ctx.new
+      refute ctx.ignore_mdc_error
+
+      ctx.set_ctx_flag("ignore-mdc-error", "1")
+      assert ctx.ignore_mdc_error
+    end
+
+    it "unsets the value for a flag with a getter" do
+      ctx = GPGME::Ctx.new(ignore_mdc_error: true)
+      assert ctx.ignore_mdc_error
+
+      ctx.set_ctx_flag("ignore-mdc-error", "0")
+      refute ctx.ignore_mdc_error
+    end
+
+    it "can set flags without getters and setters" do
+      ctx = GPGME::Ctx.new
+
+      assert_equal "", ctx.get_ctx_flag("auto-key-locate")
+      ctx.set_ctx_flag("auto-key-locate", "cert")
+      assert_equal "cert", ctx.get_ctx_flag("auto-key-locate")
+    end
+
+    it "raises an error when a flag doesn't exist" do
+      ctx = GPGME::Ctx.new
+
+      assert_raises GPGME::Error do
+        ctx.set_ctx_flag("foo", "bar")
+      end
+    end
+  end
+
   describe :armor do
     it "sets false by default" do
       ctx = GPGME::Ctx.new
@@ -101,6 +165,36 @@
     end
   end
 
+  describe :ignore_mdc_error do
+    it "sets false by default" do
+      ctx = GPGME::Ctx.new
+      refute ctx.ignore_mdc_error
+    end
+
+    it "can set" do
+      ctx = GPGME::Ctx.new
+
+      ctx.ignore_mdc_error = true
+      assert ctx.ignore_mdc_error
+    end
+
+    it "can unset" do
+      ctx = GPGME::Ctx.new(ignore_mdc_error: true)
+      assert ctx.ignore_mdc_error
+
+      ctx.ignore_mdc_error = false
+      refute ctx.ignore_mdc_error
+    end
+
+    it "can set and get in constructor" do
+      ctx = GPGME::Ctx.new(:ignore_mdc_error => false)
+      refute ctx.ignore_mdc_error
+
+      ctx = GPGME::Ctx.new(:ignore_mdc_error => true)
+      assert ctx.ignore_mdc_error
+    end
+  end
+
   describe :protocol do
     it "sets 0 by default" do
       ctx = GPGME::Ctx.new