docs: update IETF links to use datatracker

The tools.ietf.org domain has been deprecated a while now, with the
links being redirected to datatracker.ietf.org.

Rather than make people eat that redirect time, this change switches the
URL to a more canonical source.

Closes #8317

docs/ALTSVC.md

@@ -10,7 +10,7 @@ curl features support for the Alt-Svc: HTTP header.
 
 ## Standard
 
-[RFC 7838](https://tools.ietf.org/html/rfc7838)
+[RFC 7838](https://datatracker.ietf.org/doc/html/rfc7838)
 
 # Alt-Svc cache file format
 

docs/HSTS.md

@@ -5,7 +5,7 @@ HTTP Strict-Transport-Security. Added as experimental in curl
 
 ## Standard
 
-[HTTP Strict Transport Security](https://tools.ietf.org/html/rfc6797)
+[HTTP Strict Transport Security](https://datatracker.ietf.org/doc/html/rfc6797)
 
 ## Behavior
 

docs/HTTP-COOKIES.md

@@ -20,12 +20,12 @@
   In 2011, [RFC6265](https://www.ietf.org/rfc/rfc6265.txt) was finally
   published and details how cookies work within HTTP. In 2016, an update which
   added support for prefixes was
-  [proposed](https://tools.ietf.org/html/draft-ietf-httpbis-cookie-prefixes-00),
+  [proposed](https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-cookie-prefixes-00),
   and in 2017, another update was
-  [drafted](https://tools.ietf.org/html/draft-ietf-httpbis-cookie-alone-01)
+  [drafted](https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-cookie-alone-01)
   to deprecate modification of 'secure' cookies from non-secure origins. Both
   of these drafts have been incorporated into a proposal to
-  [replace](https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-02)
+  [replace](https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-rfc6265bis-02)
   RFC6265. Cookie prefixes and secure cookie modification protection has been
   implemented by curl.
 

docs/HTTP2.md

@@ -118,4 +118,4 @@ can use that hint to create a new connection asynchronously. For libcurl, we
 may introduce a way to bring such clues to the application and/or let a
 subsequent request use the alternate route automatically.
 
-[Detailed in RFC 7838](https://tools.ietf.org/html/rfc7838)
+[Detailed in RFC 7838](https://datatracker.ietf.org/doc/html/rfc7838)

docs/INTERNALS.md

@@ -1092,7 +1092,7 @@ for older and later versions as things do not change drastically that often.
 [1]: https://curl.se/libcurl/c/curl_easy_setopt.html
 [2]: https://curl.se/libcurl/c/curl_easy_init.html
 [3]: https://c-ares.org/
-[4]: https://tools.ietf.org/html/rfc7230 "RFC 7230"
+[4]: https://datatracker.ietf.org/doc/html/rfc7230 "RFC 7230"
 [5]: https://curl.se/libcurl/c/CURLOPT_ACCEPT_ENCODING.html
 [6]: https://curl.se/docs/manpage.html#--compressed
 [7]: https://curl.se/libcurl/c/curl_multi_socket_action.html
@@ -1103,4 +1103,4 @@ for older and later versions as things do not change drastically that often.
 [12]: https://curl.se/libcurl/c/curl_multi_fdset.html
 [13]: https://curl.se/libcurl/c/curl_multi_add_handle.html
 [14]: https://curl.se/libcurl/c/curl_multi_info_read.html
-[15]: https://tools.ietf.org/html/rfc7231#section-3.1.2.2
+[15]: https://datatracker.ietf.org/doc/html/rfc7231#section-3.1.2.2

docs/KNOWN_BUGS

@@ -196,7 +196,7 @@ problems may have been fixed or changed somewhat since this was written.
  something beyond ascii but currently libcurl will only pass in the verbatim
  string the app provides. There are several browsers that already do this
  encoding. The key seems to be the updated draft to RFC2231:
- https://tools.ietf.org/html/draft-reschke-rfc2231-in-http-02
+ https://datatracker.ietf.org/doc/html/draft-reschke-rfc2231-in-http-02
 
 1.5 Expect-100 meets 417
 
@@ -808,7 +808,7 @@ problems may have been fixed or changed somewhat since this was written.
 
  Curl sends DNS requests for hostnames with a .onion TLD. This leaks
  information about what the user is attempting to access, and violates this
- requirement of RFC7686: https://tools.ietf.org/html/rfc7686
+ requirement of RFC7686: https://datatracker.ietf.org/doc/html/rfc7686
 
  Issue: https://github.com/curl/curl/issues/543
 

docs/ROADMAP.md

@@ -14,7 +14,7 @@ eventually remove the "experimental" label from this functionality.
 
 As a DNS version of alt-svc and also a pre-requisite for ECH (see below).
 
-See: https://tools.ietf.org/html/draft-ietf-dnsop-svcb-https-02
+See: https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-svcb-https-02
 
 ## ECH (Encrypted Client Hello - formerly known as ESNI)
 

docs/SSL-PROBLEMS.md

@@ -70,7 +70,7 @@
 
   References:
 
-  https://tools.ietf.org/html/draft-popov-tls-prohibiting-rc4-01
+  https://datatracker.ietf.org/doc/html/draft-popov-tls-prohibiting-rc4-01
 
 ## Allow BEAST
 

docs/TODO

@@ -413,7 +413,7 @@
 
  https://bugzilla.mozilla.org/show_bug.cgi?id=1220810
 
- https://tools.ietf.org/html/draft-ietf-dnsop-let-localhost-be-localhost-02
+ https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-let-localhost-be-localhost-02
 
 1.28 FD_CLOEXEC
 
@@ -554,7 +554,7 @@
  HOST is a command for a client to tell which host name to use, to offer FTP
  servers named-based virtual hosting:
 
- https://tools.ietf.org/html/rfc7151
+ https://datatracker.ietf.org/doc/html/rfc7151
 
 4.2 Alter passive/active on failure and retry
 
@@ -887,7 +887,7 @@
  that previously (in older TLS version) were not set. The clienthello
  extension adds padding to avoid that size range.
 
- https://tools.ietf.org/html/rfc7685
+ https://datatracker.ietf.org/doc/html/rfc7685
  https://github.com/curl/curl/issues/2299
 
 14. GnuTLS

docs/URL-SYNTAX.md

@@ -5,7 +5,7 @@
 The official "URL syntax" is primarily defined in these two different
 specifications:
 
- - [RFC 3986](https://tools.ietf.org/html/rfc3986) (although URL is called
+ - [RFC 3986](https://datatracker.ietf.org/doc/html/rfc3986) (although URL is called
    "URI" in there)
  - [The WHATWG URL Specification](https://url.spec.whatwg.org/)
 
@@ -331,7 +331,7 @@ Search for an empty DN and request information about the
     ldap://ldap.example.com/?rootDomainNamingContext
 
 For more information about the individual components of a LDAP URL please
-see [RFC 4516](https://tools.ietf.org/html/rfc4516).
+see [RFC 4516](https://datatracker.ietf.org/doc/html/rfc4516).
 
 ## POP3