socket: fix recvmsg without argument

* ext/socket/ancdata.c (bsock_recvmsg_internal): grow buffer
  on unspecified maxdatlen
  [ruby-core:71517] [Bug #11701]
* ext/socket/lib/socket.rb (Socket#recvmsg): nil default for dlen
  (Socket#recvmsg_nonblock): ditto
* test/socket/test_socket.rb (test_recvmsg_udp_no_arg): new test

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52625 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 3 insertions, 3 deletions

diff --git a/ext/socket/ancdata.c b/ext/socket/ancdata.c
index 168f70c311..8fcd53c9fb 100644
--- a/ext/socket/ancdata.c
+++ b/ext/socket/ancdata.c
@@ -1465,7 +1465,7 @@ bsock_recvmsg_internal(VALUE sock,
     int gc_done = 0;
 #endif
 
-    maxdatlen = NUM2SIZET(vmaxdatlen);
+    maxdatlen = NIL_P(vmaxdatlen) ? 4061 : NUM2SIZET(vmaxdatlen);
 #if defined(HAVE_STRUCT_MSGHDR_MSG_CONTROL)
     maxctllen = NIL_P(vmaxctllen) ? 4096 : NUM2SIZET(vmaxctllen);
 #else
diff --git a/ext/socket/lib/socket.rb b/ext/socket/lib/socket.rb
index 58e7dfd92a..0240c2094e 100644
--- a/ext/socket/lib/socket.rb
+++ b/ext/socket/lib/socket.rb
@@ -425,7 +425,7 @@ class BasicSocket < IO
   #       return ancdata.unix_rights[0]
   #     end
   #   }
-  def recvmsg(dlen = 4096, flags = 0, clen = nil, scm_rights: false)
+  def recvmsg(dlen = nil, flags = 0, clen = nil, scm_rights: false)
     __recvmsg(dlen, flags, clen, scm_rights)
   end
 
@@ -441,7 +441,7 @@ class BasicSocket < IO
   # By specifying `exception: false`, the _opts_ hash allows you to indicate
   # that recvmsg_nonblock should not raise an IO::WaitWritable exception, but
   # return the symbol :wait_writable instead.
-  def recvmsg_nonblock(dlen = 4096, flags = 0, clen = nil,
+  def recvmsg_nonblock(dlen = nil, flags = 0, clen = nil,
                        scm_rights: false, exception: true)
     __recvmsg_nonblock(dlen, flags, clen, scm_rights, exception)
   end