Bug fix---use calculated max number of segments

Per Tony Finch [1], the maximum number of segments are:

	I had a quick look and I noticed that it sets the maximum number of
	labels to 100.  The actual maximum is 128, because the maximum
	length of a DNS name is 255, and the minimum length of a label is 2
	(except for the root which is 1), and (255 - 1)/2 + 1 == 128.

https://lobste.rs/s/tukocy/network_protocols_sans_i_o_2016#c_495uaz

Makefile

@@ -22,7 +22,7 @@ UNAME   := $(shell uname)
 VERSION := $(shell git describe --tag)
 
 ifeq ($(VERSION),)
-  VERSION=v2.1.0
+  VERSION=v2.1.3
 endif
 
 # ===================================================

org.conman.dns-2.1.0-1.rockspec → org.conman.dns-2.1.3-1.rockspec

@@ -1,8 +1,8 @@
 package = "org.conman.dns"
-version = "2.1.0-1"
+version = "2.1.3-1"
 source = {
    url = "git+https://github.com/spc476/SPCDNS.git",
-   tag = "v2.1.0"
+   tag = "v2.1.3"
 }
 description = {
    summary = "A Lua module to encode DNS queries and decode DNS answers.",

src/codec.c

@@ -96,12 +96,13 @@
 /*---------------------------------------------------------------------------
 ; This is the maximum number of domain labels to encode.  The domain
 ; "example.com" contains two domain labels.  "1.0.0.127.in-addr.arpa" has
-; six domain labels.  This value is an arbitrary limit to avoid doing any
-; memory allocations but I feel it's sufficiently large enough to avoid any
-; limits.  I hope.
+; six domain labels.  This value is calculated was calculated by Tony Finch
+; [1] based upon the maximum domain name length, and minimum segment length.
+;
+; [1] https://lobste.rs/s/tukocy/network_protocols_sans_i_o_2016#c_495uaz
 ;----------------------------------------------------------------------------*/
 
-#define MAXSEG  100
+#define MAXSEG  128
 
 /*---------------------------------------------------------------------------
 ; You really, no, I mean it, *REALLY* need to read RFC-1876 to understand