Renamed header -> field per quic-qpack naming convention, in particular:
- Header Field -> Field Line
- Header Block -> (Encoded) Field Section
- Without Name Reference -> With Literal Name
- Header Acknowledgement -> Section Acknowledgment
Control characters (0x00-0x1f, 0x7f) and space are not expected to appear
in the Host header. Requests with such characters in the Host header are
now unconditionally rejected.
In 71edd9192f24 logging of invalid headers which were rejected with the
NGX_HTTP_PARSE_INVALID_HEADER error was restricted to just the "client
sent invalid header line" message, without any attempts to log the header
itself.
This patch returns logging of the header up to the invalid character and
the character itself. The r->header_end pointer is now properly set
in all cases to make logging possible.
The same logging is also introduced when parsing headers from upstream
servers.
Control characters (0x00-0x1f, 0x7f), space, and colon were never allowed in
header names. The only somewhat valid use is header continuation which nginx
never supported and which is explicitly obsolete by RFC 7230.
Previously, such headers were considered invalid and were ignored by default
(as per ignore_invalid_headers directive). With this change, such headers
are unconditionally rejected.
It is expected to make nginx more resilient to various attacks, in particular,
with ignore_invalid_headers switched off (which is inherently unsecure, though
nevertheless sometimes used in the wild).
Control characters (0x00-0x1f, 0x7f) were never allowed in URIs, and must
be percent-encoded by clients. Further, these are not believed to appear
in practice. On the other hand, passing such characters might make various
attacks possible or easier, despite the fact that currently allowed control
characters are not significant for HTTP request parsing.
From now on, requests with spaces in URIs are immediately rejected rather
than allowed. Spaces were allowed in 31e9677b15a1 (0.8.41) to handle bad
clients. It is believed that now this behaviour causes more harm than
good.
Per RFC 3986 only the following characters are allowed in URIs unescaped:
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@"
sub-delims = "!" / "$" / "&" / "'" / "(" / ")"
/ "*" / "+" / "," / ";" / "="
And "%" can appear as a part of escaping itself. The following
characters are not allowed and need to be escaped: %00-%1F, %7F-%FF,
" ", """, "<", ">", "\", "^", "`", "{", "|", "}".
Not escaping ">" is known to cause problems at least with MS Exchange (see
http://nginx.org/pipermail/nginx-ru/2010-January/031261.html) and in
Tomcat (ticket #2191).
The patch adds escaping of the following chars in all URI parts: """, "<",
">", "\", "^", "`", "{", "|", "}". Note that comments are mostly preserved
to outline important characters being escaped.
HTTP clients are not allowed to generate such requests since Transfer-Encoding
introduction in RFC 2068, and they are not expected to appear in practice
except in attempts to perform a request smuggling attack. While handling of
such requests is strictly defined, the most secure approach seems to reject
them.
No valid CONNECT requests are expected to appear within nginx, since it
is not a forward proxy. Further, request line parsing will reject
proper CONNECT requests anyway, since we don't allow authority-form of
request-target. On the other hand, RFC 7230 specifies separate message
length rules for CONNECT which we don't support, so make sure to always
reject CONNECTs to avoid potential abuse.
Previously, TRACE requests were rejected before parsing Transfer-Encoding.
This is not important since keepalive is not enabled at this point anyway,
though rejecting such requests after properly parsing other headers is
less likely to cause issues in case of further code changes.
After 2096b21fcd10, a single RST_STREAM(NO_ERROR) may not result in an error.
This change removes several unnecessary ctx->type checks for such a case.
As per quic-http-34, these are the cases when this error should be generated:
If an endpoint receives a second SETTINGS frame
on the control stream, the endpoint MUST respond with a connection
error of type H3_FRAME_UNEXPECTED
SETTINGS frames MUST NOT be sent on any stream other than the control
stream. If an endpoint receives a SETTINGS frame on a different
stream, the endpoint MUST respond with a connection error of type
H3_FRAME_UNEXPECTED.
A client MUST NOT send a PUSH_PROMISE frame. A server MUST treat the
receipt of a PUSH_PROMISE frame as a connection error of type
H3_FRAME_UNEXPECTED; see Section 8.
The MAX_PUSH_ID frame is always sent on the control stream. Receipt
of a MAX_PUSH_ID frame on any other stream MUST be treated as a
connection error of type H3_FRAME_UNEXPECTED.
Receipt of an invalid sequence of frames MUST be treated as a
connection error of type H3_FRAME_UNEXPECTED; see Section 8. In
particular, a DATA frame before any HEADERS frame, or a HEADERS or
DATA frame after the trailing HEADERS frame, is considered invalid.
A CANCEL_PUSH frame is sent on the control stream. Receiving a
CANCEL_PUSH frame on a stream other than the control stream MUST be
treated as a connection error of type H3_FRAME_UNEXPECTED.
The GOAWAY frame is always sent on the control stream.
The quic-http-34 is ambiguous as to what error should be generated for the
first frame in control stream:
Each side MUST initiate a single control stream at the beginning of
the connection and send its SETTINGS frame as the first frame on this
stream. If the first frame of the control stream is any other frame
type, this MUST be treated as a connection error of type
H3_MISSING_SETTINGS.
If a DATA frame is received on a control stream, the recipient MUST
respond with a connection error of type H3_FRAME_UNEXPECTED.
If a HEADERS frame is received on a control stream, the recipient MUST
respond with a connection error of type H3_FRAME_UNEXPECTED.
Previously, H3_FRAME_UNEXPECTED had priority, but now H3_MISSING_SETTINGS has.
The arguments in the spec sound more compelling for H3_MISSING_SETTINGS.
- Function ngx_quic_control_flow() is introduced. This functions does
both MAX_DATA and MAX_STREAM_DATA flow controls. The function is called
from STREAM and RESET_STREAM frame handlers. Previously, flow control
was only accounted for STREAM. Also, MAX_DATA flow control was not accounted
at all.
- Function ngx_quic_update_flow() is introduced. This function advances flow
control windows and sends MAX_DATA/MAX_STREAM_DATA. The function is called
from RESET_STREAM frame handler, stream cleanup handler and stream recv()
handler.
Recent fixes to SSL shutdown with lingering close (554c6ae25ffc, 1.19.5)
broke logging of SSL variables. To make sure logging of SSL variables
works properly, avoid freeing c->ssl when doing an SSL shutdown before
lingering close.
Reported by Reinis Rozitis
(http://mailman.nginx.org/pipermail/nginx/2021-May/060670.html).
Instead of calling SSL_free() with each return point, introduced a single
place where cleanup happens. As a positive side effect, this fixes two
potential memory leaks on ngx_handle_read_event() and ngx_handle_write_event()
errors where there were no SSL_free() calls (though unlikely practical,
as errors there are only expected to happen due to bugs or kernel issues).
When starting processing a new encoder instruction, the header state is not
memzero'ed because generally it's burdensome. If the header value is empty,
this resulted in inserting a stale value left from the previous instruction.
Based on a patch by Zhiyong Sun.
On Linux, SO_REUSEADDR allows completely duplicate UDP sockets, so using
SO_REUSEADDR when testing configuration results in packets being dropped
if there is an existing traffic on the sockets being tested (ticket #2187).
While dropped packets are expected with UDP, it is better to avoid this
when possible.
With this change, SO_REUSEADDR is no longer set on datagram sockets when
testing configuration.
Since we anyway do not set SO_REUSEPORT when testing configuration
(see ecb5cd305b06), trying to open additional sockets does not make much
sense, as all these additional sockets are expected to result in EADDRINUSE
errors from bind(). On the other hand, there are reports that trying
to open these sockets takes significant time under load: total configuration
testing time greater than 15s was observed in ticket #2188, compared to less
than 1s without load.
With this change, no additional sockets are opened during testing
configuration.
As per quic-transport 34, FINAL_SIZE_ERROR is generated if an endpoint received
a STREAM frame or a RESET_STREAM frame containing a final size that was lower
than the size of stream data that was already received.
Since nginx always uses exactly one entry in the question section of
a DNS query, and never uses compression pointers in this entry, parsing
of a DNS response in ngx_resolver_process_response() does not expect
compression pointers to appear in the question section of the DNS
response. Indeed, compression pointers in the first name of a DNS response
hardly make sense, do not seem to be allowed by RFC 1035 (which says
"a pointer to a prior occurance of the same name", note "prior"), and
were never observed in practice.
Added an explicit check to ngx_resolver_process_response()'s parsing
of the question section to properly report an error if compression pointers
nevertheless appear in the question section.
Instead of checking on each label if we need to place a dot or not,
now it always adds a dot after a label, and reduces the resulting
length afterwards.
