Merge pull request bitcoin#1646 from pinheadmz/353-cat-txt

bip353: concatenate strings in TXT record

Author: murchandamus

bip-0353.mediawiki

@@ -50,6 +50,8 @@ Note that because resolvers are not required to support resolving non-ASCII iden
 
 Clients resolving Bitcoin payment instructions MUST ignore any TXT records at the same label which do not begin with (ignoring case) "bitcoin:". Resolvers encountering multiple "bitcoin:"-matching TXT records at the same label MUST treat the records as invalid and refuse to use any payment instructions therein.
 
+Clients resolving Bitcoin payment instructions MUST concatenate all strings in the TXT record before processing the complete URI.<ref>TXT records are defined as "one or more character-strings" in [[https://www.rfc-editor.org/rfc/rfc1035#section-3.3.14|RFC 1035]], and a "character-string" is a single byte (with a max value of 255) followed by that many characters.</ref>
+
 Clients resolving Bitcoin payment instructions MUST fully validate DNSSEC signatures leading to the DNS root (including any relevant CNAME or DNAME records) and MUST NOT accept DNSSEC signatures which use SHA-1 or RSA with keys shorter than 1024 bits. Resolvers MAY accept SHA-1 DS records.
 
 Clients resolving Bitcoin payment instructions MUST NOT trust a remote resolver to validate DNSSEC records on their behalf.
@@ -114,15 +116,28 @@ This work is intended to extend and subsume the existing "Lightning Address" sch
 
 == Examples ==
 
-`[email protected]` resolves to
-`matt.user._bitcoin-payment.mattcorallo.com. 3600 IN TXT	"bitcoin:?lno=lno1qsgqmqvgm96frzdg8m0gc6nzeqffvzsqzrxqy32afmr3jn9ggkwg3egfwch2hy0l6jut6vfd8vpsc3h89l6u3dm4q2d6nuamav3w27xvdmv3lpgklhg7l5teypqz9l53hj7zvuaenh34xqsz2sa967yzqkylfu9xtcd5ymcmfp32h083e805y7jfd236w9afhavqqvl8uyma7x77yun4ehe9pnhu2gekjguexmxpqjcr2j822xr7q34p078gzslf9wpwz5y57alxu99s0z2ql0kfqvwhzycqq45ehh58xnfpuek80hw6spvwrvttjrrq9pphh0dpydh06qqspp5uq4gpyt6n9mwexde44qv7lstzzq60nr40ff38u27un6y53aypmx0p4qruk2tf9mjwqlhxak4znvna5y"`
-Note that `lno` indicates a value containing a lightning BOLT12 offer.
+<code>[email protected]</code> resolves to
+
+<pre>matt.user._bitcoin-payment.mattcorallo.com. 1800 IN TXT  "bitcoin:?lno=lno1qsgr30k45jhvkfqxjqheaetac
+u4guyxvqttftvqu0f5sneckep3lkwdut7mmhhpcyjmlmnjn4hze8ed7pq88xqkxt2dcw5mlxhz644fms82f7k4ymfxs2ehhpjtxw
+xly0w5k8xdtlvpqyd8xzdq4tq8lgupnueshgydr330lc3j5kdcqh54gt7jdg9n68j4eqqeu7ts8uh0qxamee6ndj37tc6mzgejth
+vvjqj96p8dz2h" "rsh5z5n27qfk6svjz5pmkh0smq26k0j2j4q36xgq3r5qzet9kuhq4lydpen5mskxgjdvs5faqgv8pmj7cfd7
+ny84djksqpqk9ky6juc7fpezecxvg7sjx05dckyypnv9tmvfp6tkpehmtaqmvuupetxuzqf4t0azddjdcpasgw6hxuz9g"
+</pre>
+
+* Note that `lno` indicates a value containing a lightning BOLT12 offer.
+* Note that the complete URI is broken into two strings with maximum 255 characters each
 
 == Reference Implementations ==
 * A DNSSEC proof generation and validation implementation can be found at https://git.bitcoin.ninja/index.cgi?p=dnssec-prover;a=summary
 * A lightning-specific name to payment instruction resolver can be found at https://git.bitcoin.ninja/index.cgi?p=lightning-resolver;a=summary
 * Reference implementations for parsing the URI contents can be found in [[bip-0021.mediawiki|BIP 21]].
 
+
+== Footnotes ==
+
+<references />
+
 == Acknowledgements ==
 
 Thanks to Rusty Russell for the concrete address rotation suggestion.