- Enhances the documentation of mbedtls_ssl_get_bytes_avail (return
the number of bytes left in the current application data record, if
there is any).
- Introduces a new public function mbedtls_ssl_check_pending for
checking whether any data in the internal buffers still needs to be
processed. This is necessary for users implementing event-driven IO
to decide when they can safely idle until they receive further
events from the underlying transport.
Give a note on the debugging output on the following occasions:
(1) The timer expires in mbedtls_ssl_fetch_input
(2) There's more than one records within a single datagram
As done by previous commits for ECC and ECDSA:
- use explicit state assignments rather than increment
- always place the state update right before the operation label
This will make it easier to add restart support for other operations later if
desired.
SSL-specific changes:
- remove useless states: when the last restartable operation on a message is
complete, ssl->state is incremented already, so we don't need any additional
state update: ecrs_state is only meant to complement ssl->state
- rename remaining states consistently as <message>_<operation>
- move some labels closer to the actual operation when possible (no assignment
to variables used after the label between its previous and current position)
Goals include:
- reducing the number of local variables in the main function (so that we
don't have to worry about saving/restoring them)
- reducing the number exit points in the main function, making it easier to
update ssl->state only right before we return
- more consistent naming with ecrs prefix for everything
- always check it enabled before touching the rest
- rm duplicated code in parse_server_hello()
This commit fixes the following case: If a client is both expecting a
SERVER_HELLO and has an application data record that's partially
processed in flight (that's the situation the client gets into after
receiving a ServerHelloRequest followed by ApplicationData), a
subsequent call to mbedtls_ssl_read will set keep_current_message = 1
when seeing the unexpected application data, but not reset it to 0
after the application data has been processed. This commit fixes this.
It also documents and suggests how the problem might be solved in a
more structural way on the long run.
This commit adds a hard assertion to mbedtls_ssl_read_record_layer
triggering if both ssl->in_hslen and ssl->in_offt are not 0. This
should never happen, and if it does, there's no sensible way of
telling whether the previous message was a handshake or an application
data message.
There are situations in which it is not clear what message to expect
next. For example, the message following the ServerHello might be
either a Certificate, a ServerKeyExchange or a CertificateRequest. We
deal with this situation in the following way: Initially, the message
processing function for one of the allowed message types is called,
which fetches and decodes a new message. If that message is not the
expected one, the function returns successfully (instead of throwing
an error as usual for unexpected messages), and the handshake
continues to the processing function for the next possible message. To
not have this function fetch a new message, a flag in the SSL context
structure is used to indicate that the last message was retained for
further processing, and if that's set, the following processing
function will not fetch a new record.
This commit simplifies the usage of this message-retaining parameter
by doing the check within the record-fetching routine instead of the
specific message-processing routines. The code gets cleaner this way
and allows retaining messages to be used in other situations as well
without much effort. This will be used in the next commits.
This commit adds four tests to tests/ssl-opt.sh:
(1) & (2): Check behaviour of optional/required verification when the
trusted CA chain is empty.
(3) & (4): Check behaviour of optional/required verification when the
client receives a server certificate with an unsupported curve.
This commit changes the behaviour of mbedtls_ssl_parse_certificate
to make the two authentication modes MBEDTLS_SSL_VERIFY_REQUIRED and
MBEDTLS_SSL_VERIFY_OPTIONAL be in the following relationship:
Mode == MBEDTLS_SSL_VERIFY_REQUIRED
<=> Mode == MBEDTLS_SSL_VERIFY_OPTIONAL + check verify result
Also, it changes the behaviour to perform the certificate chain
verification even if the trusted CA chain is empty. Previously, the
function failed in this case, even when using optional verification,
which was brought up in #864.
* gilles/IOTSSL-1330/development:
Changelog entry for the bug fixes
SSLv3: when refusing renegotiation, stop processing
Ignore failures when sending fatal alerts
Cleaned up double variable declaration
Code portability fix
Added changelog entry
Send TLS alerts in many more cases
Skip all non-executables in run-test-suites.pl
SSL tests: server requires auth, client has no certificate
Balanced braces across preprocessor conditionals
Support setting the ports on the command line
By default, keep allowing SHA-1 in key exchange signatures. Disabling
it causes compatibility issues, especially with clients that use
TLS1.2 but don't send the signature_algorithms extension.
SHA-1 is forbidden in certificates by default, since it's vulnerable
to offline collision-based attacks.
Default to forbidding the use of SHA-1 in TLS where it is unsafe: for
certificate signing, and as the signature hash algorithm for the TLS
1.2 handshake signature. SHA-1 remains allowed in HMAC-SHA-1 in the
XXX_SHA ciphersuites and in the PRF for TLS <= 1.1.
For easy backward compatibility for use in controlled environments,
turn on the MBEDTLS_TLS_DEFAULT_ALLOW_SHA1 compiled-time option.
* hanno/sig_hash_compatibility:
Improve documentation
Split long lines
Remember suitable hash function for any signature algorithm.
Introduce macros and functions to characterize certain ciphersuites.
According to RFC5246 the server can indicate the known Certificate
Authorities or can constrain the aurhorisation space by sending a
certificate list. This part of the message is optional and if omitted,
the client may send any certificate in the response.
The previous behaviour of mbed TLS was to always send the name of all the
CAs that are configured as root CAs. In certain cases this might cause
usability and privacy issues for example:
- If the list of the CA names is longer than the peers input buffer then
the handshake will fail
- If the configured CAs belong to third parties, this message gives away
information on the relations to these third parties
Therefore we introduce an option to suppress the CA list in the
Certificate Request message.
Providing this feature as a runtime option comes with a little cost in
code size and advantages in maintenance and flexibility.
This commit changes `ssl_parse_signature_algorithms_ext` to remember
one suitable ( := supported by client and by our config ) hash
algorithm per signature algorithm.
It also modifies the ciphersuite checking function
`ssl_ciphersuite_match` to refuse a suite if there
is no suitable hash algorithm.
Finally, it adds the corresponding entry to the ChangeLog.
In many places in TLS handling, some code detects a fatal error, sends
a fatal alert message, and returns to the caller. If sending the alert
fails, then return the error that triggered the alert, rather than
overriding the return status. This effectively causes alert sending
failures to be ignored. Formerly the code was inconsistently sometimes
doing one, sometimes the other.
In general ignoring the alert is the right thing: what matters to the
caller is the original error. A typical alert failure is that the
connection is already closed.
One case which remains not handled correctly is if the alert remains
in the output buffer (WANT_WRITE). Then it won't be sent, or will be
truncated. We'd need to either delay the application error or record
the write buffering notice; to be done later.
The TLS client and server code was usually closing the connection in
case of a fatal error without sending an alert. This commit adds
alerts in many cases.
Added one test case to detect that we send the alert, where a server
complains that the client's certificate is from an unknown CA (case
tracked internally as IOTSSL-1330).
Fix an incorrect condition in ssl_check_ctr_renegotiate() that compared
64 bits of record counter instead of 48 bits as described in RFC 6347
Section 4.3.1. This would cause the function's return value to be
occasionally incorrect and the renegotiation routines to be triggered
at unexpected times.
Fixes many typos, and errors in comments.
* Clarifies many comments
* Grammar correction in config.pl help text
* Removed comment about MBEDTLS_X509_EXT_NS_CERT_TYPE.
* Comment typo fix (Dont => Don't)
* Comment typo fix (assure => ensure)
* Comment typo fix (byes => bytes)
* Added citation for quoted standard
* Comment typo fix (one complement => 1's complement)
The is some debate about whether to prefer "one's complement", "ones'
complement", or "1's complement". The more recent RFCs related to TLS
(RFC 6347, RFC 4347, etc) use " 1's complement", so I followed that
convention.
* Added missing ")" in comment
* Comment alignment
* Incorrect comment after #endif
Certificates with unsupported algorithms in the certificate chain
prevented verification even if a certificate before the unsupported
ones was already trusted.
We change the behaviour to ignoring every certificate with unknown
(unsupported) signature algorithm oid when parsing the certificate
chain received from the peer.
Separates platform time abstraction into it's own header from the
general platform abstraction as both depend on different build options.
(MBEDTLS_PLATFORM_C vs MBEDTLS_HAVE_TIME)
Since the buffer is used in a few places, it seems Clang isn't clever
enough to realise that the first byte is never touched. So, even though
the function has a correct null check for ssl->handshake, Clang
complains. Pulling the handshake type out into its own variable is
enough for Clang's analysis to kick in though.
The callback typedefs defined for mbedtls_ssl_set_bio() and
mbedtls_ssl_set_timer_cb() were not used consistently where the callbacks were
referenced in structures or in code.
After the record contents are decompressed, in_len is no longer
accessed directly, only in_msglen is accessed. in_len is only read by
ssl_parse_record_header() which happens before ssl_prepare_record_contents().
This is also made clear by the fact that in_len is not touched after
decrypting anyway, so if it was accessed after that it would be wrong unless
decryption is used - as this is not the case, it show in_len is not accessed.
When the peer retransmits a flight with many record in the same datagram, and
we already saw one of the records in that datagram, we used to drop the whole
datagram, resulting in interoperability failure (spurious handshake timeouts,
due to ignoring record retransmitted by the peer) with some implementations
(issues with Chrome were reported).
So in those cases, we want to only drop the current record, and look at the
following records (if any) in the same datagram. OTOH, this is not something
we always want to do, as sometime the header of the current record is not
reliable enough.
This commit introduces a new return code for ssl_parse_header() that allows to
distinguish if we should drop only the current record or the whole datagram,
and uses it in mbedtls_ssl_read_record()
fixes#345
* iotssl-519-asn1write-overflows-restricted:
Fix other int casts in bounds checking
Fix other occurrences of same bounds check issue
Fix potential buffer overflow in asn1write
fixes#310
Actually all key exchanges that use a certificate use signatures too, and
there is no key exchange that uses signatures but no cert, so merge those two
flags.
Not a security issue as here we know the buffer is large enough (unless
something else if badly wrong in the code), and the value cast to int is less
than 2^16 (again, unless issues elsewhere).
Still changing to a more correct check as a matter of principle
* development: (73 commits)
Bump yotta dependencies version
Fix typo in documentation
Corrected misleading fn description in ssl_cache.h
Corrected URL/reference to MPI library
Fix yotta dependencies
Fix minor spelling mistake in programs/pkey/gen_key.c
Bump version to 2.1.2
Fix CVE number in ChangeLog
Add 'inline' workaround where needed
Fix references to non-standard SIZE_T_MAX
Fix yotta version dependencies again
Upgrade yotta dependency versions
Fix compile error in net.c with musl libc
Add missing warning in doc
Remove inline workaround when not useful
Fix macroization of inline in C++
Changed attribution for Guido Vranken
Merge of IOTSSL-476 - Random malloc in pem_read()
Fix for IOTSSL-473 Double free error
Fix potential overflow in CertificateRequest
...
Conflicts:
include/mbedtls/ssl_internal.h
library/ssl_cli.c
- "master secret" is the usual name
- move key block arg closer to the related lengths
- document lengths
Also fix some trailing whitespace while at it
This is more consistent, as it doesn't make any sense for a user to be able to
set up an EC J-PAKE password with TLS if the corresponding key exchange is
disabled.
Arguably this is what we should de for other key exchanges as well instead of
depending on ECDH_C etc, but this is an independent issue, so let's just do
the right thing with the new key exchange and fix the other ones later. (This
is a marginal issue anyway, since people who disable all ECDH key exchange are
likely to also disable ECDH_C in order to minimize footprint.)
Especially for resumed handshake, it's entirely possible for an epoch=0
ClientHello to be retransmitted or arrive so late that the server is already
at epoch=1. There is no good way to detect whether it's that or a reconnect.
However:
- a late ClientHello seems more likely that client going down and then up
again in the middle of a handshake
- even if that's the case, we'll time out on that handshake soon enough
- we don't want to break handshake flows that used to work
So the safest option is to not treat that as a reconnect.
Don't depend on srv.c in config.h, but add explicit checks. This is more
in line with other options that only make sense server-side, and also it
allows to test full config minus srv.c more easily.
Use a custom function that minimally parses the message an creates a reply
without the overhead of a full SSL context.
Also fix dependencies: needs DTLS_HELLO_VERIFY for the cookie types, and let's
also depend on SRV_C as is doesn't make sense on client.
This is not very useful for TLS as mbedtls_ssl_write() will automatically
fragment and return the length used, and the application should check for that
anyway, but this is useful for DTLS where mbedtls_ssl_write() returns an
error, and the application needs to be able to query the maximum length
instead of just guessing.
This is not required nor recommended by the protocol, and it's a layering
violation, but it's a know flaw in the protocol that you can't detect a PSK
auth error in any other way, so it is probably the right thing to do.
closes#227
We document that either of recv or recv_timeout may be NULL, but for TLS we
always used recv... Thanks Coverity for catching that.
(Not remotely trigerrable: local configuration.)
Also made me notice net_recv_timeout didn't do its job properly.
While at it, fix the following:
- on server with RSA_PSK, we don't want to set flags (client auth happens via
the PSK, no cert is expected).
- use safer tests (eg == OPTIONAL vs != REQUIRED)
- DTLS_HELLO_VERIFY no longer depends on SRV_C
- SSL_COOKIE_C no longer depends on DTLS_HELLO_VERIFY
Not that much work for us, and easier on users (esp. since it allows just
disabling SRV_C alone).
- Only the server needs to generate/parse tickets
- Only the client needs to store them
Also adjust prototype of ssl_conf_session_tickets() while at it.
Initially thought it would be per-connection, but since max_version is in conf
too, and you need to lower that for a fallback connection, the fallback flag
should be in the same place
A simple series of sed invocations.
This is the first step, purely internal changes. The conf substructure is not
ready to be shared between contexts yet.
Note from future self: actually md_init_ctx will be re-introduced with the
same signature later, and a new function with the additional argument will be
added.
* mbedtls-1.3:
Use link-time garbage collection in memory.sh
scripts/memory.sh only work on Linux
Add missing 'const' on selftest data
Use only headers for doxygen (no doc in C files)
Add missing extern "C" guard in aesni.h
Fix compile error with renego disabled
Remove slow PKCS5 test
Stop checking key-cert match systematically
Make tests/*.sh runnable from anywhere
Update visual C files
* mbedtls-1.3:
Rename website and repository
Move private macro from header to C file
Add some missing 'static' on a few objects
Fix whitespace issues
Minor portability fix in benchmark
* development:
Fix the fix to ssl_set_psk()
Update Changelog
Finish fixing memleak in ssl_server2 arg parsing
Fix another potential memory leak found by find-mem-leak.cocci.
Add a rule for another type of memory leak to find-mem-leak.cocci.
Fix a potential memory leak found by find-mem-leak.cocci.
Add a semantic patch to find potential memory leaks.
Fix whitespace of 369e6c20.
Apply the semantic patch rm-malloc-cast.cocci.
Add a semantic patch to remove casts of malloc.
* rasp/mem-leak:
Fix another potential memory leak found by find-mem-leak.cocci.
Add a rule for another type of memory leak to find-mem-leak.cocci.
Fix a potential memory leak found by find-mem-leak.cocci.
Add a semantic patch to find potential memory leaks.
Fix whitespace of 369e6c20.
Apply the semantic patch rm-malloc-cast.cocci.
Add a semantic patch to remove casts of malloc.
Conflicts:
programs/ssl/ssl_server2.c
* development: (100 commits)
Update Changelog for the mem-measure branch
Fix issues introduced when rebasing
Fix compile error in memory_buffer_alloc_selftest
Code cosmetics
Add curve25519 to ecc-heap.sh
Add curve25519 to the benchmark program
Fix compile issue when buffer_alloc not available
New script ecc-heap.sh
Fix unused variable issue in some configs
Rm usunused member in private struct
Add heap usage for PK in benchmark
Use memory_buffer_alloc() in benchmark if available
Only define mode_func if mode is enabled (CBC etc)
PKCS8 encrypted key depend on PKCS5 or PKCS12
Disable SRV_C for client measurement
Output stack+heap usage with massif
Enable NIST_OPTIM by default for config-suite-b
Refactor memory.sh
Adapt memory.sh to config-suite-b
Adapt mini-client for config-suite-b.h
...
Conflicts:
ChangeLog
include/polarssl/net.h
library/Makefile
library/error.c
library/ssl_tls.c
programs/Makefile
programs/ssl/ssl_client2.c
programs/ssl/ssl_server2.c
tests/Makefile
* development: (46 commits)
Fix url again
Fix small bug in base64_encode()
Fix depend that was checked but not documented
Fix dependency that was not checked
Minor gitginore fixes
Move some ignore patterns to subdirectories
Ignore CMake/MSVC-related build files.
Re-categorize changelog entry
Fix misattribution
Minor nits with stdout/stderr.
Add cmake compatibility targets
Add script for polarssl symlink creation
Fix more stdio inclusion issues
Add debug info for cert/suite selection
Fix possible portability issue
Fix bug in ssl_get_verify_result()
aescrypt2.c local char array not initial
Update Changelog
Fix mips64 bignum implementation
Fix usage string of ssl_client2
...
Conflicts:
include/polarssl/ssl.h
library/CMakeLists.txt
library/Makefile
programs/Makefile
programs/ssl/ssl_client2.c
programs/ssl/ssl_server2.c
visualc/VS2010/PolarSSL.sln
visualc/VS2010/mbedTLS.vcxproj
visualc/VS6/mbedtls.dsp
visualc/VS6/mbedtls.dsw
* development:
Update copyright
Fix issue in compat.sh
Rename doxyfile
Rename to mbed TLS in tests/
Rename to mbed TLS in examples
Remove old test certificates.
Rename to mbed TLS in the documentation/comments
Change name to mbed TLS in the copyright notice
Conflicts:
doxygen/input/doc_mainpage.h
doxygen/mbedtls.doxyfile
include/polarssl/version.h
tests/compat.sh
* development:
Adapt tests to new defaults/errors.
Fix typos/cosmetics in Changelog
Disable RC4 by default in example programs.
Add ssl_set_arc4_support()
Set min version to TLS 1.0 in programs
Conflicts:
include/polarssl/ssl.h
library/ssl_cli.c
library/ssl_srv.c
tests/compat.sh
* commit '36adc36':
Add support for getrandom()
Use library default for trunc-hmac in ssl_client2
Make truncated hmac a runtime option server-side
Fix portability issue in script
Specific error for suites in common but none good
Prefer SHA-1 certificates for pre-1.2 clients
Some more refactoring/tuning.
Minor refactoring
Conflicts:
include/polarssl/error.h
include/polarssl/ssl.h
library/error.c
* commit 'b2eaac1':
Stop assuming chars are signed
Add tests for CBC record splitting
Fix tests that were failing with record splitting
Allow disabling record splitting at runtime
Add 1/n-1 record splitting
Enhance doc on ssl_write()
Conflicts:
include/polarssl/ssl.h
programs/ssl/ssl_client2.c
programs/ssl/ssl_server2.c
* commit 'f6080b8':
Fix warning in reduced configs
Adapt to "negative" switch for renego
Add tests for periodic renegotiation
Make renego period configurable
Auto-renegotiate before sequence number wrapping
Update Changelog for compile-option renegotiation
Switch from an enable to a disable flag
Save 48 bytes if SSLv3 is not defined
Make renegotiation a compile-time option
Add tests for renego security enforcement
Conflicts:
include/polarssl/ssl.h
library/ssl_cli.c
library/ssl_srv.c
library/ssl_tls.c
programs/ssl/ssl_server2.c
tests/ssl-opt.sh
* commit 'd7e2483': (57 commits)
Skip signature_algorithms ext if PSK only
Fix bug in ssl_client2 reconnect option
Cosmetics in ssl_server2
Improve debugging message.
Fix net_usleep for durations greater than 1 second
Use pk_load_file() in X509
Create ticket keys only if enabled
Fix typo in #ifdef
Clarify documentation a bit
Fix comment on resumption
Update comment from draft to RFC
Use more #ifdef's on CLI_C and SRV_C in ssl_tls.c
Add recursion.pl to all.sh
Allow x509_crt_verify_child() in recursion.pl
Set a compile-time limit to X.509 chain length
Fix 3DES -> DES in all.sh (+ time estimates)
Add curves.pl to all.sh
Rework all.sh to use MSan instead of valgrind
Fix depends on individual curves in tests
Add script to test depends on individual curves
...
Conflicts:
CMakeLists.txt
programs/ssl/ssl_client2.c
* commit '8b9bcec':
Stop assuming chars are signed
Fix len miscalculation in buffer-based allocator
Fix NULL dereference in buffer-based allocator
Add test_suite_memory_buffer_alloc
Add memory_buffer_alloc_self_test()
Fix missing bound check
Add test for ctr_drbg_update() input sanitizing
Refactor for clearer correctness/security
Stop assuming chars are signed
Conflicts:
library/ssl_tls.c
Rationale: if people want to disable RC4 but otherwise keep the default suite
list, it was cumbersome. Also, since it uses a global array,
ssl_list_ciphersuite() is not a convenient place. So the SSL modules look like
the best place, even if it means temporarily adding one SSL setting.
Reading the documentation of ssl_set_truncated_hmac() may give the impression
I changed the default for clients but I didn't, the old documentation was
wrong.
* etm:
Fix warning in reduced config
Update Changelog for EtM
Keep EtM state across renegotiations
Adjust minimum length for EtM
Don't send back EtM extension if not using CBC
Fix for the RFC erratum
Implement EtM
Preparation for EtM
Implement initial negotiation of EtM
Conflicts:
include/polarssl/check_config.h
* session-hash:
Update Changelog for session-hash
Make session-hash depend on TLS versions
Forbid extended master secret with SSLv3
compat.sh: allow git version of gnutls
compat.sh: make options a bit more robust
Implement extended master secret
Add negotiation of Extended Master Secret
Conflicts:
include/polarssl/check_config.h
programs/ssl/ssl_server2.c
Works only with GnuTLS for now, OpenSSL packs other records in the same
datagram after the last fragmented one, which we don't handle yet.
Also, ssl-opt.sh fails the tests with valgrind for now: we're so slow with
valgrind that gnutls-serv retransmits some messages, and we don't handle
duplicated messages yet.
case
The actual input / output buffer overhead is only 301 instead of 512.
This requires a proper check on the padding_idx to prevent out of bounds
reads.
Previously a remote party could potentially trigger an access error and
thus stop the application when sending a malicious packet having
MAX_CONTENT_LEN of data, 32 bytes of MAC and a decrypted padlen of .
This would result in reading from in_ctr + 13 + 32 + MAX_CONTENT_LEN - 1 - 1
for 256 bytes (including fake padding check). Or 13 + 32 bytes over the
buffer length.
We now reset padding_idx to 0, if it's clear that it will never be a
valid padding (padlen > msg_len || msg_len + padlen + 256 > buffer_len)
- avoid "multi-line comment" warning in ssl_client2.c
- rm useless initialisation of mfl_code in ssl_init()
- const-correctness of ssl_parse_*_ext()
- a code formating issue
The SHA4 name was not clear with regards to the new SHA-3 standard. So
SHA2 and SHA4 have been renamed to better represent what they are:
SHA256 and SHA512 modules.
More fixes based on the compiler directives -Wcast-qual -Wwrite-strings
-Wmissing-prototypes -Wmissing-declarations. Not everything with regards
to -Wcast-qual has been fixed as some have unwanted consequences for the
rest of the code.
All symmetric cipher algorithms and hash algorithms now include support
for a POLARSSL_XXX_ALT flag that prevents the definition of the
algorithm context structure and all 'core' functions.
(cherry picked from commit 4087c47043)
code selection
The base RFC 4279 DHE-PSK ciphersuites are now supported and added.
The SSL code cuts out code not relevant for defined key exchange methods
The ciphersuites parameter in the ssl_session structure changed from
'int *' to 'int *[4]'.
The new function ssl_set_ciphersuite_for_version() sets specific entries
inside this array. ssl_set_ciphersuite() sets all entries to the same
value.
(cherry picked from commit a62729888b)
Conflicts:
ChangeLog
library/ssl_srv.c
library/ssl_tls.c
Made all modifications to include Ephemeral Elliptic Curve Diffie
Hellman ciphersuites into the existing SSL/TLS modules. All basic
handling of the ECDHE-ciphersuites (TLS_ECDHE_RSA_WITH_NULL_SHA,
TLS_ECDHE_RSA_WITH_RC4_128_SHA, TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA)
has been included.
New padding checking is unbiased on correct or incorrect padding and
has no branch prediction timing differences.
The additional MAC checks further straighten out the timing differences.
The flag POLARSSL_SSL_ALERT_MESSAGES switched between enabling and
disabling the sending of alert messages that give adversaries intel
about the result of their action. PolarSSL can still communicate with
other parties if they are disabled, but debugging of issues might be
harder.
process
Single stepping the handshake process allows for better support of
non-blocking network stacks and for getting information from specific
handshake messages if wanted.
