I'd like to propose a slight tweak for
TSHttpTxnClientProtocolStackContains and
TSHttpSsnClientProtocolStackContains
Replace the tag argument with two explicit input and output arguments, e.g.
int TSHttpTxnClientProtocolStackContains(TSHttpTxn txnp, char const
*contains_tag, char const **specific_tag_ptr)
I think having separate arguments for input and output arguments is clearer.
Also if I don't care about getting a pointer back to the specific tag string
that ATS uses internally I don't have to declare additional variables to make
this call, e.g.
if (TXHttpTxnClientProtocolStackContains(txnp, "h2", NULL)) {
// Do HTTP/2 stuff
}
On 8/20/2016 10:20 AM, Alan Carroll wrote:
After discussions with Leif and Bryan, here is an updated proposal. This would
subsume Oliver Goodman's API, which would be simply calling this and looking
for / passing 'ws' as the protocol tag.
There is an unresolved point, which is the exact stack returned for a HTTP/2
connection.
.. include:: ../../../common.defs
.. default-domain:: c
TSClientProtocolStack
*********************
Synopsis
========
`#include <ts/ts.h>`
.. function:: TSReturnCode TSHttpTxnClientProtocolStackGet(TSHttpTxn txnp, int
n, char const** result, int* actual)
.. function:: TSReturnCode TSHttpSsnClientProtocolStackGet(TSHttpSsn ssnp, int
n, char const** result, int* actual)
.. function:: int TSHttpTxnClientProtocolStackContains(TSHttpTxn txnp, char
const** tag)
.. function:: int TSHttpSsnClientProtocolStackContains(TSHttpSsn ssnp, char
const** tag)
.. function:: char const* TSNormalizedProtocolTag(char const* tag)
.. function:: char const* TSRegisterProtocolTag(char const* tag)
Description
===========
These functions are used to explore the protocol stack of the client (user
agent) connection to |TS|. The functions
:func:`TSHttpTxnClientProtocolStackGet` and
:func:`TSHttpSsnClientProtocolStackGet` can be used to retrieve the entire
protocol stack for the user agent connection.
:func:`TSHttpTxnClientProtocolStackContains` and
:func:`TSHttpSsnClientProtocolStackContains` will check for a specific protocol
:arg:`tag` being present in the stack.
Each protocol is represented by tag which is a null terminated string. A
particular tag will always be returned as the same character pointer and so
protocols can be reliably checked with pointer comparisons.
:func:`TSNormalizedProtocolTag` will return this character pointer for a
specific :arg:`tag`. A return value of :const:`NULL` indicates the provided
:arg:`tag` is not registered as a known protocol tag.
:func:`TSRegisterProtocolTag` registers the :arg:`tag` and then returns its
normalized value. This is useful for plugins that provide custom protocols for
user agents.
The protocols are ordered from higher level protocols to the lower level ones on which
the higher operate. For instance a stack might look like
"http/1.1,tls/1.2,tcp,ipv4". For :func:`TSHttpTxnClientProtocolStackGet` and
:func:`TSHttpSsnClientProtocolStackGet` these values are placed in the array
:arg:`result`. :arg:`count` is the maximum number of elements of :arg:`result` that may
be modified by the function call. If :arg:`actual` is not :const:`NULL` then the actual
number of elements in the protocol stack will be returned. If this is equal or less than
:arg:`count` then all elements were returned. If it is larger then some layers were
omitted from :arg:`result`. If the full stack is required :arg:`actual` can be used to
resize :arg:`result` to be sufficient to hold all of the elements and the function called
again with updated :arg:`count` and :arg:`result`. In practice the maximum number of
elements will is almost certain to be less than 10 which therefore should suffice. These
functions return :const:`TS_SUCCESS` on success and :const:`TS_ERROR` on failure which
should only occurr if :arg:`txnp` or :arg:`ssnp` are invalid.
The :func:`TSHttpTxnClientProtocolStackContains` and :func:`TSHttpSsnClientProtocolStackContains` functions
are provided for the convenience when only the presence of a protocol is of interest, not its location or the
presence of other protocols. These functions return 0 if the protocol :arg:`tag` is not present, non-zero if
it is present. The strings are matched with an anchor prefix search, as with debug tags. For instance if
:arg:`tag` is "tls" then it will match "tls/1.2" or "tls/1.3". This makes
checking for TLS or IP more convenient. If more precision is required the entire protocol stack can be
retrieved and processed more thoroughly.
The protocol tags defined by |TS|.
=========== =========
Protocol Tag
=========== =========
HTTP/1.1 http/1.1
HTTP/1.0 http/1.0
HTTP/2 h2
WebSocket ws
TLS 1.3 tls/1.3
TLS 1.2 tls/1.2
TCP tcp
UDP udp
IPv4 ipv4
IPv6 ipv6
QUIC quic
=========== =========
.. note::
What should HTTP/2 connections return as the top protocol? There are
several options
* "http/1.1,h2"
* "h2"
* "http/1.1,h2" for transctions and "h2" for sessions.
