There was a small optimization for PowerPCs to pre-increment a
pointer when accessing a word, instead of post-incrementing. This
required prefacing the loop with a decrement of the pointer,
possibly pointing before the object passed. This is not compliant
with the C standard, for which decrementing a pointer before its
allocated memory is undefined. When tested on a modern PowerPC
with a modern compiler, the optimization no longer has any effect.
Due to all that, and per the recommendation of a security audit of
the zlib code by Trail of Bits and TrustInSoft, in support of the
Mozilla Foundation, this "optimization" was removed, in order to
avoid the possibility of undefined behavior.
d1d577490c.patch
For h1 / ws, a combination of removing POLLIN wait and
stashing any unused rx lets us immediately respond to
rx flow control requests in a simple and effective way,
because the tcp socket is the stream.
But for muxed protocols like h2, that technique cannot
be used because we cannot silence the whole bundle of
streams because one can't handle any more rx dynamically.
There are control frames and content for other streams
serialized inbetween the flow controlled stream content.
We have no choice but to read to so we can see the other
things. Therefore for muxed protocols like h2 and spdy,
rx flow control boils down to tx credit manipulation
on individual streams to staunch the flow at the peer.
However that requires a round trip to take effect, any
transmitted packets that were in flight before the tx credit
reduction arrives at the remote peer are still going to come
and have to be dealt with by adding them to the stash.
This patch introduces lws_buflist scatter-gather type
buffer management for rxflow handling, so we can append
buffer segments in a linked-list to handle whatever rx
is unavoidably in flight on a stream that is trying to
assert rx flow control.
Since new roles may be incompatible with http, add support for
alpn names at the role struct, automatic generation of the
default list of alpn names that servers advertise, and the
ability to override the used alpn names per-vhost and per-
client connection.
This not only lets you modulate visibility or use of h2,
but also enables vhosts that only offer non-http roles,
as well as restricting http role vhosts to only alpn
identifiers related to http roles.
By itself the HTTP layer can track transaction sizes only with
content-length, including on POST.
However it's also possible for whatever logically interprets
the payload to determine its length, for example with multipart,
the multipart headers can do that job.
This allows the spa stuff to drive the content length tracking,
so lws can interpret multipart POST client payload without needing
an overall content-length.
This adds h2 http support for the client api.
The public client api requires no changes, it will detect by
ALPN if the server can handle http/2, if so, it will use it.
Multiple client connections using the lws api will be mapped on
to the same single http/2 + tls socket using http/2 streams
that are serviced simultaneously where possible.
This completely removes the loop self-running stuff.
Static allocations (uv_idle, timers etc) are referenced-counted in the context
same as the wsi are. When lws wants to close, he first closes all his wsi, then
when that is completed in the uv close callbacks, he closes all of his static
uv handles. When that is also completed in the uv callbacks, he stops the loop
so the lws context can destroy and exit.
Any direct libuv allocations in protocol handlers must participate in the
reference counting. Two new apis are provided
- lws_libuv_static_refcount_add(handle, context) to mark the handle with
a pointer to the context and increment the global uv object counter
- lws_libuv_static_refcount_del() which should be used as the close callback
for your own libuv objects declared in the protocol scope.
Previously down network interfaces without an IPv4 address are
removed from the posix api that lists network interfaces.
That means if you bound a vhost listen socket to a particular
interface, it will fail at startup time.
This patch adds these vhosts to a list, starts the vhost without
a listen socket, and checks to see if the vhost's network interface
has appeared while the rest of lws is running.
If it appears, the listen socket is opened on the network interface
and the vhost becomes reachable.
This just supports "http/1.1" alpn and lets the client know it
can use keepalive earlier if it affirmitively negotiated
"http/1.1" on alpn.
mbedTLS wrapper needed a small adaptation to also allow
per-client-ssl control of the alpn negotiation list.
