Mailing List Archive

commit 7e47da7222d4fe84ebb89e992ca102624758b33d
Author: Dridi Boukelmoune <dridi.boukelmoune@gmail.com>
Date: Thu Mar 28 16:34:35 2024 +0100

param: Document mapping to HTTP/2 settings

With the exception of h2_max_header_list_size that is not advertised as
such despite being ent as part of the initial SETTINGS frame. The same
parameter also sees its default and maximum values updated to 2^32-1.

This is based on this sentence from rfc9113:

> The initial value of this setting is unlimited.

This aligns the h2_max_header_list_size parameter with the values set in
h2_settings.h for MAX_HEADER_LIST_SIZE.

diff --git a/include/tbl/params.h b/include/tbl/params.h
index 600bf6a55..2a31810fb 100644
--- a/include/tbl/params.h
+++ b/include/tbl/params.h
@@ -1207,6 +1207,12 @@ PARAM_SIMPLE(
/* flags */ WIZARD
)

+#define H2_SETTING_NAME(nm) "SETTINGS_" #nm
+#define H2_SETTING_DESCR(nm) \
+ "\n\nThe value of this parameter defines " H2_SETTING_NAME(nm) \
+ " in the initial SETTINGS frame sent to the client when a new " \
+ "HTTP2 session is established."
+
PARAM_SIMPLE(
/* name */ h2_header_table_size,
/* type */ bytes_u,
@@ -1218,6 +1224,7 @@ PARAM_SIMPLE(
"HTTP2 header table size.\n"
"This is the size that will be used for the HPACK dynamic\n"
"decoding table."
+ H2_SETTING_DESCR(HEADER_TABLE_SIZE)
)

PARAM_SIMPLE(
@@ -1231,6 +1238,7 @@ PARAM_SIMPLE(
"HTTP2 Maximum number of concurrent streams.\n"
"This is the number of requests that can be active\n"
"at the same time for a single HTTP2 connection."
+ H2_SETTING_DESCR(MAX_CONCURRENT_STREAMS)
)

/* We have a strict min at the protocol default here. This is because we
@@ -1246,7 +1254,8 @@ PARAM_SIMPLE(
/* def */ "65535b",
/* units */ "bytes",
/* descr */
- "HTTP2 initial flow control window size.",
+ "HTTP2 initial flow control window size."
+ H2_SETTING_DESCR(INITIAL_WINDOW_SIZE)
)

PARAM_SIMPLE(
@@ -1258,19 +1267,23 @@ PARAM_SIMPLE(
/* units */ "bytes",
/* descr */
"HTTP2 maximum per frame payload size we are willing to accept."
+ H2_SETTING_DESCR(MAX_FRAME_SIZE)
)

PARAM_SIMPLE(
/* name */ h2_max_header_list_size,
/* type */ bytes_u,
/* min */ "0b",
- /* max */ NULL,
- /* def */ "2147483647b",
+ /* max */ "4294967295b",
+ /* def */ "4294967295b",
/* units */ "bytes",
/* descr */
"HTTP2 maximum size of an uncompressed header list."
)

+#undef H2_SETTING_DESCR
+#undef H2_SETTING_NAME
+
#define H2_RR_INFO \
"Changes to this parameter affect the default for new HTTP2 " \
"sessions. vmod_h2(3) can be used to adjust it from VCL."
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