Juliusz Sosinowicz
b0fdaa2a6d
RFC 8446 section 8 requires any server instance to accept 0-RTT for a
given ClientHello at most once. Prior to this change wolfSSL's behaviour
diverged from that requirement in several ways:
* ctx->maxEarlyDataSz defaulted to MAX_EARLY_DATA_SZ whenever the
library was built with WOLFSSL_EARLY_DATA, so servers auto-
advertised 0-RTT in NewSessionTicket without the application
asking. RFC 8446 E.5 says 0-RTT MUST NOT be enabled unless
specifically requested.
* The post-accept eviction is compiled out under NO_SESSION_CACHE,
so builds without the cache accepted 0-RTT with no replay defence.
* Stateless self-encrypted tickets do not carry a session ID on the
stateless DoClientTicket decrypt path, so wolfSSL_SSL_CTX_remove_
session could not locate them to evict.
* wolfSSL_SSL_CTX_remove_session always returned 0 on success
regardless of whether the session was actually in the cache,
diverging from OpenSSL's SSL_CTX_remove_session (1 on success,
0 on not-found).
Changes:
* src/internal.c: ctx->maxEarlyDataSz defaults to 0; applications
must opt in with wolfSSL_CTX_set_max_early_data.
* src/tls13.c: #error when WOLFSSL_EARLY_DATA is built with
HAVE_SESSION_TICKET and NO_SESSION_CACHE. Escape hatch
WOLFSSL_EARLY_DATA_NO_ANTI_REPLAY for deployments that take
application-layer responsibility.
* wolfssl/internal.h: imply WOLFSSL_TICKET_HAVE_ID from
WOLFSSL_EARLY_DATA so stateless-ticket issuance populates the
cache under an ID that eviction can find.
* src/ssl_sess.c: wolfSSL_SSL_CTX_remove_session returns 1 when the
session was found (internal-cache hit, or ctx->rem_sess_cb fired
for an external cache), 0 otherwise. Matches OpenSSL semantics.
* src/tls13.c: the 0-RTT acceptance condition in CheckPreSharedKeys
now calls wolfSSL_SSL_CTX_remove_session and checks its return:
the eviction is the check. If the session was in the cache, 0-RTT
is accepted and the single-use requirement is satisfied. If not,
the early_data extension is rejected through the normal path so
the record layer correctly skips in-flight 0-RTT records.
WOLFSSL_MSG at each rejection site.
* doc/dox_comments/header_files/ssl.h: document runtime opt-in.
* tests: four new tests —
test_tls13_0rtt_default_off (fails without default-to-0 fix),
test_tls13_0rtt_stateless_replay (fails without TICKET_HAVE_ID
implication and remove_session gate),
test_tls13_remove_session_return (fails without return-value fix),
test_tls13_0rtt_ext_cache_eviction (fails without ext-cache
counts-as-found fix).
test_tls13_early_data explicitly opts in via
wolfSSL_CTX_set_max_early_data.
tests/api.c: two SSL_CTX_remove_session == 0 assertions updated
to == 1.
wolfSSL examples directory
client and server
These directories contain a client (client.c) and server (server.c) that utilize a variety of the wolfSSL library's capabilities. The manner in which both programs operate can depend on the configure or can be specified at run-time depending on the end goal. Both applications contain testing as well as benchmarking code.
Compile
./configure
make
Usage
./examples/server/server
./examples/client/client
Run ./examples/server/server -h and ./examples/client/client -h for usage details.
For simpler wolfSSL TLS server/client examples, visit https://github.com/wolfSSL/wolfssl-examples/tree/master/tls
echoclient and echoserver
These directories contain a client (echoclient.c) and server (echoserver.c) that establish a connection encrypted by wolfSSL. Like the names indicate, once the connection has been established any messages entered into echoclient are sent to and displayed on the echoserver and are then echoed back to echoclient. The nature of the encryption, as well as additional behavior of the two programs, depends on how wolfSSL was configured ( DTLS enabled/disabled, Filesystem enabled/disabled, etc ... ).
Compile
./configure
make
Usage
./examples/echoserver/echoserver
./examples/echoclient/echoclient
benchmark
The benchmark directory offers an application that can help you grasp just how well wolfSSL's TLS functionality is performing on your local machine.
Compile
./configure
make
Usage
./examples/benchmark/tls_bench
The tls_bench executable can also be compiled separately with gcc -lwolfssl -lpthread -o tls_bench tls_bench.c.
Run ./examples/benchmark/tls_bench -? for usage details.
sctp
This directory contains servers and clients that demonstrate wolfSSL's DTLS-SCTP support.
Compile
./configure --enable-sctp
make
Usage
./examples/sctp/sctp-server
./examples/sctp/sctp-client
and
./examples/sctp/sctp-server-dtls
./examples/sctp/sctp-client-dtls
configs
This directory contains example wolfSSL configuration file templates for use when autoconf is not available, such as building with a custom IDE.
See configs/README.md for more details.
asn1
This directory contains an example that prints the ASN.1 data of a BER/DER or PEM encoded file. Configure wolfSSL with --enable-asn-print.
pem
This directory contains an example of converting to/from PEM and DER. Configure wolfSSL with --enable-coding