Age | Commit message (Collapse) | Author |
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This is a preparation for improvements to come in option handling and
support for TLS-1.3
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When the server_name_indication is sent automatize the
clients check of that the hostname is present in the
servers certificate. Currently server_name_indication shall
be on the dns_id format. If server_name_indication is disabled
it is up to the user to do its own check in the verify_fun.
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Note this is a change form how it works for earlier versions that will
send the first hello message on the lowest supported version.
From RFC 5246
Appendix E. Backward Compatibility
E.1. Compatibility with TLS 1.0/1.1 and SSL 3.0
Since there are various versions of TLS (1.0, 1.1, 1.2, and any
future versions) and SSL (2.0 and 3.0), means are needed to negotiate
the specific protocol version to use. The TLS protocol provides a
built-in mechanism for version negotiation so as not to bother other
protocol components with the complexities of version selection.
TLS versions 1.0, 1.1, and 1.2, and SSL 3.0 are very similar, and use
compatible ClientHello messages; thus, supporting all of them is
relatively easy. Similarly, servers can easily handle clients trying
to use future versions of TLS as long as the ClientHello format
remains compatible, and the client supports the highest protocol
version available in the server.
A TLS 1.2 client who wishes to negotiate with such older servers will
send a normal TLS 1.2 ClientHello, containing { 3, 3 } (TLS 1.2) in
ClientHello.client_version. If the server does not support this
version, it will respond with a ServerHello containing an older
version number. If the client agrees to use this version, the
negotiation will proceed as appropriate for the negotiated protocol.
If the version chosen by the server is not supported by the client
(or not acceptable), the client MUST send a "protocol_version" alert
message and close the connection.
If a TLS server receives a ClientHello containing a version number
greater than the highest version supported by the server, it MUST
reply according to the highest version supported by the server.
A TLS server can also receive a ClientHello containing a version
number smaller than the highest supported version. If the server
wishes to negotiate with old clients, it will proceed as appropriate
for the highest version supported by the server that is not greater
than ClientHello.client_version. For example, if the server supports
TLS 1.0, 1.1, and 1.2, and client_version is TLS 1.0, the server will
proceed with a TLS 1.0 ServerHello. If server supports (or is
willing to use) only versions greater than client_version, it MUST
send a "protocol_version" alert message and close the connection.
Whenever a client already knows the highest protocol version known to
a server (for example, when resuming a session), it SHOULD initiate
the connection in that native protocol.
Note: some server implementations are known to implement version
negotiation incorrectly. For example, there are buggy TLS 1.0
servers that simply close the connection when the client offers a
version newer than TLS 1.0. Also, it is known that some servers will
refuse the connection if any TLS extensions are included in
ClientHello. Interoperability with such buggy servers is a complex
topic beyond the scope of this document, and may require multiple
connection attempts by the client.
Earlier versions of the TLS specification were not fully clear on
what the record layer version number (TLSPlaintext.version) should
contain when sending ClientHello (i.e., before it is known which
version of the protocol will be employed). Thus, TLS servers
compliant with this specification MUST accept any value {03,XX} as
the record layer version number for ClientHello.
TLS clients that wish to negotiate with older servers MAY send any
value {03,XX} as the record layer version number. Typical values
would be {03,00}, the lowest version number supported by the client,
and the value of ClientHello.client_version. No single value will
guarantee interoperability with all old servers, but this is a
complex topic beyond the scope of this document.
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Fragment reassembling needs to handle that a smaller
fragment then sent originally might overlap an earlier
received fragment.
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The new_options_in_accept test is not working yet, however DTLS is still
work in progress and we want to make a progress merge to avoid merge conflicts
with other progress of the ssl application.
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DTLS does not support stream ciphers and needs diffrent
handling of the "#ssl_socket{}" handle .
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Beta DTLS, not production ready. Only very basically tested, and
not everything in the SPEC is implemented and some things
are hard coded that should not be, so this implementation can not be consider
secure.
Refactor "TLS connection state" and socket handling, to facilitate
DTLS implementation.
Create dtls "listner" (multiplexor) process that spawns
DTLS connection process handlers.
Handle DTLS fragmentation.
Framework for handling retransmissions.
Replay Detection is not implemented yet.
Alerts currently always handled as in TLS.
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changed:
* initialize deocder state when needed
* remove retransmission indicator support
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The MSS might change between sending the a flight and possible
resend. We therefore have to be able to fragment the records
differently for resent.
Encoding and fragmenting of handshake record therefor needs to
be done independently.
With this change the handshake is encoded to it's full length
first, then queued to a flight. The fragmentation is handled
during assembly of the flights datagram.
Conflicts:
lib/ssl/src/dtls_connection.erl
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* henrik/update-copyrightyear:
update copyright-year
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In TLS-1.2 The signature algorithm and the hash function algorithm
used to produce the digest that is used when creating the digital signature
may be negotiated through the signature algorithm extension RFC 5246.
We want to make these algorithm pairs configurable.
In connections using lower versions of TLS these algorithms are
implicit defined and can not be negotiated or configured.
DTLS is updated to not cause dialyzer errors, but needs to get a real
implementation later.
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This commit adds support for RFC7301, application-layer protocol
negotiation. ALPN is the standard based approach to the NPN
extension, and is required for HTTP/2.
ALPN lives side by side with NPN and provides an equivalent
feature but in this case it is the server that decides what
protocol to use, not the client.
When both ALPN and NPN are sent by a client, and the server is
configured with both ALPN and NPN options, ALPN will always
take precedence. This behavior can also be found in the OpenSSL
implementation of ALPN.
ALPN and NPN share the ssl:negotiated_protocol/1 function for
retrieving the negotiated protocol. The previously existing
function ssl:negotiated_next_protocol/1 still exists, but has
been deprecated and removed from the documentation.
The tests against OpenSSL require OpenSSL version 1.0.2+.
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Even if DTLS is not finished, e.i. not runnable yet we
want to phase in the code together with refactoring of TLS code,
but without introducing warnings in the release.
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See RFC 6066 section 3
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The DTLS fragment reassembler use a list [{Start, End}] for the
fragments. When the first received fragment was not the starting
fragment, that list got initialized with [{Start, Length}],
causing the merge of following fragment to fail.
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Common functions will be located in ssl_handshake.erl while
specific functions will be located in tls_handshake.erl and dtls_handshake.erl
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This code is to 99 % written by Andreas Schultz only some small changes
to start integrating with OTPs DTLS solution.
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Also phase in tls module as main API instead of ssl. To
make API clearer. As TLS is the new protocol name.
Maybe keep some API functions in ssl
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