The function htx_add_data_before() was removed because it was buggy. The
function htx_move_blk_before() may be used if necessary to do something
equivalent, except it just moves blocks. It doesn't handle the adding.
In an HTX message, it may have 2 available rooms to store a new block. The first
one is between the blocks and their payload. Blocks are added starting from the
end of the buffer and their payloads are added starting from the begining. So
the first free room is between these 2 edges. The second one is at the begining
of the buffer, when we start to wrap to add new payloads. Once we start to use
this one, the other one is ignored until the next defragmentation of the HTX
message.
In theory, there is no problem. But in practice, some lacks in the HTX structure
force us to defragment too often HTX messages to always be in a known state. The
second free room is not tracked as it should do and the first one may be easily
corrupted when rewrites happen.
So to fix the problem and avoid unecessary defragmentation, the HTX structure
has been refactored. The front (the block's position of the first payload before
the blocks) is no more stored. Instead we keep the relative addresses of 3 edges:
* tail_addr : The start address of the free space in front of the the blocks
table
* head_addr : The start address of the free space at the beginning
* end_addr : The end address of the free space at the beginning
Here is the general view of the HTX message now:
head_addr end_addr tail_addr
| | |
V V V
+------------+------------+------------+------------+------------------+
| | | | | |
| PAYLOAD | Free space | PAYLOAD | Free space | Blocks area |
| ==> | 1 | ==> | 2 | <== |
+------------+------------+------------+------------+------------------+
<head_addr> is always lower or equal to <end_addr> and <tail_addr>. <end_addr>
is always lower or equal to <tail_addr>.
In addition;, to simplify everything, the blocks area are now contiguous. It
doesn't wrap anymore. So the head is always the block with the lowest position,
and the tail is always the one with the highest position.
The function htx_add_data_before() is buggy and cannot work. It first add a data
block and then move it before another one, passed in argument. The problem
happens when a defragmentation is done to add the new block. In this case, the
reference is no longer valid, because the blocks are rearranged. So, instead of
moving the new block before the reference, it is moved at the head of the HTX
message.
So this function has been removed. It was only used by the compression filter to
add a last data block before a TLR, EOT or EOM block. Now, the new function
htx_add_last_data() is used. It adds a last data block, after all others and
before any TLR, EOT or EOM block. Then, the next bock is get. It is the first
non-data block after data in the HTX message. The compression loop continues
with it.
This patch must be backported to 1.9.
This type of blocks is useless because transition between data and trailers is
obvious. And when there is no trailers, the end-of-message is still there to
know when data end for chunked messages.
HTTP trailers are now parsed in the same way headers are. It means trailers are
converted to K/V blocks followed by an end-of-trailer marker. For now, to make
things simple, the type for trailer blocks are not the same than for header
blocks. But the aim is to make no difference between headers and trailers by
using the same type. Probably for the end-of marker too.
Now instead of trying to fit 100% of the input data into the output
buffer at the risk of defragmenting it, we put what fits into it only
and return the amount of bytes transferred. In a test, compared to the
previous commit, it increases the cached data rate from 44 Gbps to
55 Gbps and saves a lot in case of large buffers : with a 1 MB buffer,
uncached transfers jumped from 700 Mbps to 30 Gbps.
In order to later allow htx_add_data() to transmit partial blocks and
avoid defragmenting the buffer, we'll need to return the number of bytes
consumed. This first modification makes the function do this and its
callers take this into account. At the moment the function still works
atomically so it returns either the block size or zero. However all
call places have been adapted to consider any value between zero and
the block size.
the function htx_find_blk() is used by only one function, htx_truncate(). So
because this function does nothing very smart, we don't use it anymore. It will
be removed by another commit.
We don't store the start-line position anymore in the HTX message. Instead we
store the first block position to analyze. For now, it is almost the same. But
once all changes will be made on this part, this position will have to be used
by HTX analyzers, and only in the analysis context, to know where the analyse
should start.
When new blocks are added in an HTX message, if the first block position is not
defined, it is set. When the block pointed by it is removed, it is set to the
block following it. -1 remains the value to unset the position. the first block
position is unset when the HTX message is empty. It may also be unset on a
non-empty message, meaning every blocks were already analyzed.
From HTX analyzers point of view, this position is always set during headers
analysis. When they are waiting for a request or a response, if it is unset, it
means the analysis should wait. But once the analysis is started, and as long as
headers are not forwarded, it points to the message start-line.
As mentionned, outside the HTX analysis, no code must rely on the first block
position. So multiplexers and applets must always use the head position to start
a loop on an HTX message.
In the function htx_xfer_blks(), we take care to transfer all headers in one
time. When the current block is a start-line, we check if there is enough space
to transfer all headers too. If not, and if the destination is empty, a parsing
error is reported on the source.
The H2 multiplexer is the only one to use this function. When a parsing error is
reported during the transfer, the flag CS_FL_EOI is also set on the conn_stream.
The field hdrs_bytes has been added in the structure htx_sl. It should be used
to set how many bytes are help by all headers, from the start-line to the
corresponding EOH block. it must be set to -1 if it is unknown.
This patch makes the function more accurate. Thanks to the function
htx_get_max_blksz(), the transfer of data has been simplified. Note that now the
total number of bytes copied (metadata + payload) is returned. This slighly
change how the function is used in the H2 multiplexer.
The head of an HTX message is heavily used whereas the wrap position is only
used when a block is added or removed. So it is more logical to store the head
position in the HTX message instead of the wrap one. The wrap position can be
easily deduced. To get it, the new function htx_get_wrap() may be used.
Fortunately, this loop does nothing. Otherwise it would have led to an infinite
loop. It was probably forgotten during a refactoring, in the early stage of the
HTX.
This patch must be backported to 1.9.
In H1 and H2, one and only one trailer block is emitted during the HTTP
parsing. So it is useless to try to append this block with the previous one,
like for data block.
This patch may be backported to 1.9.
When htx_xfer_blks() is called to move blocks from an HTX message to another
one, most of blocks must be transferred atomically. But some may be splitted if
there is not enough space to move all the block. This was true for DATA and TLR
blocks. But it is a bad idea to split trailers. During HTTP parsing, only one
TLR block is emitted. It simplifies the processing of trailers to keep the block
untouched.
This patch must be backported to 1.9 because some fixes may depend on it.
When the maximum free space available for data in the HTX message is compared to
the number of bytes to transfer, we must take into account the amount of data
already transferred. Otherwise we may move more data than expected.
This patch must be backported to 1.9.
If there is a data block when a header block is added in a HTX message, its
payload will be inserted after the data block payload. But its index will be
moved before the EOH block. So at this stage, if a new data block is added, we
will try to append its payload to the last data block (because it is also the
tail). Thus the payload of the further header block will be crushed.
This cannot happens if the payloads wrap thanks to the previous fix. But it
happens when the tail is not the front too. So now, in this case, we add a new
block instead of appending.
This patch must be backported in 1.9.
When a header is added or when a data block is added before another one, the
blocks position may be changed (but not their payloads position). For instance,
when a header is added, we move the block just before the EOH, if any. When the
payloads wraps, it is pretty annoying because we loose the last inserted
block. It is neither the tail nor the head. And it is not the front either.
It is a design problem. Waiting for fixing this problem, we force a
defragmentation in such case. Anyway, it should be pretty rare, so it's not
really critical.
This patch must be backported to 1.9.
It can happen in some cases that the last block of an H2 transfer over
HTX is truncated. This was tracked down to a leftover of an earlier
implementation of htx_xfer_blks() causing the computed size of a block
to be incorrectly calculated if a data block doesn't completely fit into
the target buffer. In practice it causes the EOM block to be attempted to
be emitted with a wrong size and the message to be truncated. One way to
reproduce this is to chain two haproxy instances in h1->h2->h1 with
httpterm as the server and h2load as the client, making many requests
between 8 and 10kB over a single connection. Usually one of the very
first requests will fail.
This fix must be backported to 1.9.
The function htx_drain() can now be used to drain data from an HTX message.
It will be used by other commits to fix bugs, so it must be backported to 1.9.
Currently htx_xfer_blks() respects the <count> limit for each block
instead of for the sum of the transfered blocks. This causes it to
return slightly more than requested when both headers and data are
present in the source buffer, which happens early in the transfer
when the reserve is still active. Thus with large enough headers,
the reserve will not be respected.
Note that this function is only called from h2_rcv_buf() thus this only
affects data entering over H2 (H2 requests or H2 responses).
This fix must be backported to 1.9.
When an HTX structure is defragmented, it is possible to retrieve the new block
corresponding to an old one. This is useful to do a defrag during a loop on
blocks, to be sure to continue looping on the good block. But, instead of
returning the address of the new block in the HTX structure, the one in the
temporary structure used to do the defrag was returned, leading to unexpected
behaviours.
This patch must be backported to 1.9.
All the HTX definition is self-contained and doesn't really depend on
anything external since it's a mostly protocol. In addition, some
external similar files (like h2) also placed in common used to rely
on it, making it a bit awkward.
This patch moves the two htx.h files into a single self-contained one.
The historical dependency on sample.h could be also removed since it
used to be there only for http_meth_t which is now in http.h.
Otherwise, after such replaces, the HTX message appears to wrap but the head
block address is not necessarily the first one. So adding new blocks will
override data of old ones.
A typo in the block type check makes this function fail all the time,
which has impact on anything rewriting a start line (set-uri, set-path
etc).
No backport needed.
HTTP/2 and above require header names to be lower cased, while HTTP/1
doesn't care. By making lower case the standard way to store header
names in HTX, we can significantly simplify all operations applying to
header names retrieved from HTX (including, but not limited to, lookups
and lower case checks which are not needed anymore).
As a side effect of replacing memcpy() with ist2bin_lc(), a small increase
of the request rate performance of about 0.5-1% was noticed on keep-alive
traffic, very likely due to memcpy() being overkill for tiny strings.
This trivial patch was marked medium because it may have a visible end-user
impact (e.g. non-HTTP compliant agent, etc).
The offset was always wrong after an HTX defragmentation because the wrong
address was used and because the update could occcur several time on the same
defragmentation.
Now, the function htx_from_buf() will set the buffer's length to its size
automatically. In return, the caller should call htx_to_buf() at the end to be
sure to leave the buffer hosting the HTX message in the right state. When the
caller can use the function htxbuf() to get the HTX message without any update
on the underlying buffer.
This only happens for connections using the h1 mux. We must be sure to force the
version to HTTP/1.1 when the version of the message is 1.1 or above. It is
important for H2 messages to not send an invalid version string (HTTP/2.0) to
peers.
Instead, we now use the htx_sl coming from the HTX message. It avoids to have
too H1 specific code in version-agnostic parts. Of course, the concept of the
start-line is higly influenced by the H1, but the structure htx_sl can be
adapted, if necessary. And many things depend on a start-line during HTTP
analyzis. Using the structure htx_sl also avoid boring conversions between HTX
version and H1 version.
If there is no start-line, this offset is set to -1. Otherwise, it is the
relative address where the start-line is stored in the data block. When the
start-line is added, replaced or removed, this offset is updated accordingly. On
remove, if the start-line is no set and if the next block is a start-line, the
offset is updated. Finally, when an HTX structure is defragmented, the offset is
also updated accordingly.
The HTX start-line is now a struct. It will be easier to extend, if needed. Same
info can be found, of course. In addition it is now possible to set flags on
it. It will be used to set some infos about the message.
Some macros and functions have been added in proto/htx.h to help accessing
different parts of the start-line.
The function htx_add_data_before() can be used to add an HTX block before
another one. For instance, it could be used to add some data before the
end-of-message marker.
The internal representation of an HTTP message, called HTX, is a structured
representation, unlike the old one which is a raw representation of
messages. Idea is to have a version-agnostic representation of the HTTP
messages, which can be easily used by to handle HTTP/1, HTTP/2 and hopefully
QUIC messages, and communication from one of them to another.
In this patch, we add types to define the internal representation itself and the
main functions to manipulate them.
