MINOR: quic: Tunable "initial_max_streams_bidi" transport parameter

Add tunable "tune.quic.frontend.max_streams_bidi" setting for QUIC frontends
to set the "initial_max_streams_bidi" transport parameter.
Add some documentation for this new setting.

doc/configuration.txt

@@ -1120,6 +1120,7 @@ The following keywords are supported in the "global" section :
    - tune.pool-low-fd-ratio
    - tune.quic.conn-buf-limit
    - tune.quic.frontend.max-idle-timeout
+   - tune.quic.frontend.max-streams-bidi
    - tune.quic.retry-threshold
    - tune.rcvbuf.client
    - tune.rcvbuf.server
@@ -2954,6 +2955,17 @@ tune.quic.frontend.max-idle-timeout <timeout>
 
   The default value is 30000.
 
+tune.quic.frontend.max-streams-bidi <number>
+  Warning: QUIC support in HAProxy is currently experimental. Configuration may
+  change without deprecation in the future.
+
+  Sets the QUIC initial_max_streams_bidi transport parameter for frontends.
+  This is the initial maximum number of bidirectional streams the remote peer
+  will be authorized to open. This determines the number of concurrent client
+  requests.
+
+  The default value is 100.
+
 tune.quic.retry-threshold <number>
   Warning: QUIC support in HAProxy is currently experimental. Configuration may
   change without deprecation in the future.

include/haproxy/global-t.h

@@ -160,6 +160,7 @@ struct global {
 #ifdef USE_QUIC
 		unsigned int quic_backend_max_idle_timeout;
 		unsigned int quic_frontend_max_idle_timeout;
+		unsigned int quic_frontend_max_streams_bidi;
 		unsigned int quic_retry_threshold;
 		unsigned int quic_streams_buf;
 #endif /* USE_QUIC */

include/haproxy/quic_tp-t.h

@@ -31,6 +31,7 @@ struct tp_preferred_address {
 #define QUIC_DFLT_ACK_DELAY_COMPONENT        3 /* milliseconds */
 #define QUIC_DFLT_MAX_ACK_DELAY             25 /* milliseconds */
 #define QUIC_DFLT_FRONT_MAX_IDLE_TIMEOUT 30000 /* milliseconds */
+#define QUIC_DFLT_FRONT_MAX_STREAMS_BIDI   100
 #define QUIC_DFLT_BACK_MAX_IDLE_TIMEOUT  30000 /* milliseconds */
 #define QUIC_ACTIVE_CONNECTION_ID_LIMIT      2 /* number of connections */
 

src/cfgparse-quic.c

@@ -76,6 +76,7 @@ static int cfg_parse_quic_tune_setting(char **args, int section_type,
 {
 	unsigned int arg = 0;
 	int prefix_len = strlen("tune.quic.");
+	const char *suffix;
 
 	if (too_many_args(1, args, err, NULL))
 		return -1;
@@ -88,9 +89,12 @@ static int cfg_parse_quic_tune_setting(char **args, int section_type,
 		return -1;
 	}
 
-	if (strcmp(args[0] + prefix_len, "conn-buf-limit") == 0)
+	suffix = args[0] + prefix_len;
+	if (strcmp(suffix, "conn-buf-limit") == 0)
 		global.tune.quic_streams_buf = arg;
-	else if (strcmp(args[0] + prefix_len, "retry-threshold") == 0)
+	else if (strcmp(suffix, "frontend.max-streams-bidi") == 0)
+		global.tune.quic_frontend_max_streams_bidi = arg;
+	else if (strcmp(suffix, "retry-threshold") == 0)
 		global.tune.quic_retry_threshold = arg;
 	else {
 		memprintf(err, "'%s' keyword not unhandled (please report this bug).", args[0]);
@@ -103,6 +107,7 @@ static int cfg_parse_quic_tune_setting(char **args, int section_type,
 static struct cfg_kw_list cfg_kws = {ILH, {
 	{ CFG_GLOBAL, "tune.quic.backend.max-idle-timeou", cfg_parse_quic_time },
 	{ CFG_GLOBAL, "tune.quic.conn-buf-limit", cfg_parse_quic_tune_setting },
+	{ CFG_GLOBAL, "tune.quic.frontend.max-streams-bidi", cfg_parse_quic_tune_setting },
 	{ CFG_GLOBAL, "tune.quic.frontend.max-idle-timeout", cfg_parse_quic_time },
 	{ CFG_GLOBAL, "tune.quic.retry-threshold", cfg_parse_quic_tune_setting },
 	{ 0, NULL, NULL }

src/haproxy.c

@@ -208,6 +208,7 @@ struct global global = {
 #ifdef USE_QUIC
 		.quic_backend_max_idle_timeout = QUIC_DFLT_BACK_MAX_IDLE_TIMEOUT,
 		.quic_frontend_max_idle_timeout = QUIC_DFLT_FRONT_MAX_IDLE_TIMEOUT,
+		.quic_frontend_max_streams_bidi = QUIC_DFLT_FRONT_MAX_STREAMS_BIDI,
 		.quic_retry_threshold = QUIC_DFLT_RETRY_THRESHOLD,
 		.quic_streams_buf = 30,
 #endif /* USE_QUIC */

src/quic_tp.c

@@ -45,7 +45,7 @@ static void quic_dflt_transport_params_cpy(struct quic_transport_params *dst)
 void quic_transport_params_init(struct quic_transport_params *p, int server)
 {
 	const uint64_t ncb_size = global.tune.bufsize - NCB_RESERVED_SZ;
-	const int max_streams_bidi = 100;
+	const int max_streams_bidi = global.tune.quic_frontend_max_streams_bidi;
 	const int max_streams_uni = 3;
 
 	/* Set RFC default values for unspecified parameters. */