HTTP status codes outside of 100..599 are considered invalid in HTTP
RFC9110. However, it is explicitely stated that range 600..999 is often
used for internal communication so in practice haproxy must be lenient
with it.
Before this patch, QPACK encoder rejected these values. This resulted in
a connection error. Fix this by extending the range of allowed values
from 100 to 999.
This is linked to github issue #2422. Once again, thanks to @yokim-git
for his help here.
This must be backported up to 2.6.
Prefix-integer encoding function was incomplete. It was not able to deal
correctly with value encoded on more than 2 bytes. This maximum value depends
on the size of the prefix, but value greater than 254 were all impacted.
Most notably, this change is required to support header name/value with
sizeable length. Previously, length was incorrectly encoded. The client thus
closed the connection with QPACK_DECOMPRESSION_ERROR.
Replace bogus call b_data() by b_room() to check if there is enough
space left in the buffer before encoding a prefix integer.
At this moment, no real scenario was found to trigger a bug related to
this change. This is probably because the buffer always contains data
(field section line and status code) before calling
qpack_encode_prefix_integer() which prevents an occurrence of this bug.
