the destruction of the socket in tls_failed_read_cb() needs to be
conditional; if reached due to a timeout on a timer that has
subsequently been reset, the socket must not be destroyed.
It fixes a corner case which was causing dig to print annoying
messages like:
14-Apr-2021 18:48:37.099 SSL error in BIO: 1 TLS error (errno:
0). Arguments: received_data: (nil), send_data: (nil), finish: false
even when all the data was properly processed.
Before this fix underlying TCP sockets could remain opened for longer
than it is actually required, causing unit tests to fail with lots of
ISC_R_TOOMANYOPENFILES errors.
The change also enables graceful SSL shutdown (before that it would
happen only in the case when isc_nm_cancelread() were called).
The isc_nm_*connect() functions were refactored to always return the
connection status via the connect callback instead of sometimes returning
the hard failure directly (for example, when the socket could not be
created, or when the network manager was shutting down).
This commit changes the connect functions in all the network manager
modules, and also makes the necessary refactoring changes in places
where the connect functions are called.
See "BUGS" section at:
https://www.openssl.org/docs/man1.1.1/man3/SSL_get_error.html
It is mentioned there that when TLS status equals SSL_ERROR_SYSCALL
AND errno == 0 it means that underlying transport layer returned EOF
prematurely. However, we are managing the transport ourselves, so we
should just resume reading from the TCP socket.
It seems that this case has been handled properly on modern versions
of OpenSSL. That being said, the situation goes in line with the
manual: it is briefly mentioned there that SSL_ERROR_SYSCALL might be
returned not only in a case of low-level errors (like system call
failures).
After the TCPDNS refactoring the initial and idle timers were broken and
only the tcp-initial-timeout was always applied on the whole TCP
connection.
This broke any TCP connection that took longer than tcp-initial-timeout,
most often this would affect large zone AXFRs.
This commit changes the timeout logic in this way:
* On TCP connection accept the tcp-initial-timeout is applied
and the timer is started
* When we are processing and/or sending any DNS message the timer is
stopped
* When we stop processing all DNS messages, the tcp-idle-timeout
is applied and the timer is started again
It is advisable to disable Nagle's algorithm for HTTP/2 connections
because multiple HTTP/2 streams could be multiplexed over one
transport connection. Thus, delays when delivering small packets could
bring down performance for the whole session. HTTP/2 is meant to be
used this way.
when called from within the context of a network thread,
isc_nm_tlsconnect() hangs. it is waiting for the socket's
result code to be updated, but that update is supposed to happen
asynchronously in the network thread, and if we're already blocking
in the network thread, it can never occur.
we can kluge around this by setting the socket result code
early; this works for most clients (including "dig"), but it causes
inconsistent behaviors that manifest as test failures in the DoH unit
test.
so we kluged around it even more by setting the socket result code
early *only when running in the network thread*. we need a better
solution for this problem, but this will do for now.
- style, cleanup, and removal of unnecessary code.
- combined isc_nm_http_add_endpoint() and isc_nm_http_add_doh_endpoint()
into one function, renamed isc_http_endpoint().
- moved isc_nm_http_connect_send_request() into doh_test.c as a helper
function; remove it from the public API.
- renamed isc_http2 and isc_nm_http2 types and functions to just isc_http
and isc_nm_http, for consistency with other existing names.
- shortened a number of long names.
- the caller is now responsible for determining the peer address.
in isc_nm_httpconnect(); this eliminates the need to parse the URI
and the dependency on an external resolver.
- the caller is also now responsible for creating the SSL client context,
for consistency with isc_nm_tlsdnsconnect().
- added setter functions for HTTP/2 ALPN. instead of setting up ALPN in
isc_tlsctx_createclient(), we now have a function
isc_tlsctx_enable_http2client_alpn() that can be run from
isc_nm_httpconnect().
- refactored isc_nm_httprequest() into separate read and send functions.
isc_nm_send() or isc_nm_read() is called on an http socket, it will
be stored until a corresponding isc_nm_read() or _send() arrives; when
we have both halves of the pair the HTTP request will be initiated.
- isc_nm_httprequest() is renamed isc__nm_http_request() for use as an
internal helper function by the DoH unit test. (eventually doh_test
should be rewritten to use read and send, and this function should
be removed.)
- added implementations of isc__nm_tls_settimeout() and
isc__nm_http_settimeout().
- increased NGHTTP2 header block length for client connections to 128K.
- use isc_mem_t for internal memory allocations inside nghttp2, to
help track memory leaks.
- send "Cache-Control" header in requests and responses. (note:
currently we try to bypass HTTP caching proxies, but ideally we should
interact with them: https://tools.ietf.org/html/rfc8484#section-5.1)
This commit completes the support for DNS-over-HTTP(S) built on top of
nghttp2 and plugs it into the BIND. Support for both GET and POST
requests is present, as required by RFC8484.
Both encrypted (via TLS) and unencrypted HTTP/2 connections are
supported. The latter are mostly there for debugging/troubleshooting
purposes and for the means of encryption offloading to third-party
software (as might be desirable in some environments to simplify TLS
certificates management).
This commit includes work-in-progress implementation of
DNS-over-HTTP(S).
Server-side code remains mostly untested, and there is only support
for POST requests.
This commit resurrects the old TLS code from
8f73c70d23e26954165fd44ce5617a95f112bcff.
It also includes numerous stability fixes and support for
isc_nm_cancelread() for the TLS layer.
The code was resurrected to be used for DoH.
