[6.0] a76864184 Introduce RAPID_RESET as a sess_close reason

[Dridi Boukelmoune]

commit a76864184a59d8094433699618d9527e3f3a2c1a
Author: Dag Haavi Finstad <daghf at varnish-software.com>
Date:   Tue Oct 17 11:20:11 2023 +0200

    Introduce RAPID_RESET as a sess_close reason
    
    Conflicts:
            bin/varnishd/VSC_main.vsc
            include/tbl/sess_close.h

diff --git a/bin/varnishd/VSC_main.vsc b/bin/varnishd/VSC_main.vsc
index 8d6277ed7..4bb4697bf 100644
--- a/bin/varnishd/VSC_main.vsc
+++ b/bin/varnishd/VSC_main.vsc
@@ -601,6 +601,14 @@
 
 	Number of session closes with Error VCL_FAILURE (VCL failure)
 
+.. varnish_vsc:: sc_rapid_reset
+       :level: diag
+       :oneliner:      Session Err RAPID_RESET
+
+       Number of times we failed an http/2 session because it hit its
+       configured limits for the number of permitted rapid stream
+       resets.
+
 .. varnish_vsc:: client_resp_500
 	:level: diag
 	:group: wrk
diff --git a/bin/varnishd/http2/cache_http2_proto.c b/bin/varnishd/http2/cache_http2_proto.c
index 514285213..fc93d2b33 100644
--- a/bin/varnishd/http2/cache_http2_proto.c
+++ b/bin/varnishd/http2/cache_http2_proto.c
@@ -45,6 +45,7 @@
 #include "vtcp.h"
 #include "vtim.h"
 
+#define H2_CUSTOM_ERRORS
 #define H2EC1(U,v,r,d) const struct h2_error_s H2CE_##U[1] = {{#U,d,v,0,1,r}};
 #define H2EC2(U,v,r,d) const struct h2_error_s H2SE_##U[1] = {{#U,d,v,1,0,r}};
 #define H2EC3(U,v,r,d) H2EC1(U,v,r,d) H2EC2(U,v,r,d)
@@ -339,7 +340,7 @@ h2_rapid_reset(struct worker *wrk, struct h2_sess *h2, struct h2_req *r2)
 		Lck_Lock(&h2->sess->mtx);
 		VSLb(h2->vsl, SLT_Error, "H2: Hit RST limit. Closing session.");
 		Lck_Unlock(&h2->sess->mtx);
-		return (H2CE_ENHANCE_YOUR_CALM);
+		return (H2CE_RAPID_RESET);
 	}
 	h2->rst_budget -= 1.0;
 	return (0);
diff --git a/bin/varnishtest/tests/r03996.vtc b/bin/varnishtest/tests/r03996.vtc
index 4d7ff8c51..c9b1a4c37 100644
--- a/bin/varnishtest/tests/r03996.vtc
+++ b/bin/varnishtest/tests/r03996.vtc
@@ -54,3 +54,5 @@ client c1 {
 	barrier b2 sync
 	stream 0 -wait
 } -run
+
+varnish v1 -expect sc_rapid_reset == 1
diff --git a/include/tbl/h2_error.h b/include/tbl/h2_error.h
index 7481b9836..8f3485c24 100644
--- a/include/tbl/h2_error.h
+++ b/include/tbl/h2_error.h
@@ -145,5 +145,17 @@ H2_ERROR(
 	/* descr */	"Use HTTP/1.1 for the request"
 )
 
+#ifdef H2_CUSTOM_ERRORS
+H2_ERROR(
+       /* name */      RAPID_RESET,
+       /* val */       11, /* ENHANCE_YOUR_CALM */
+       /* types */     1,
+       /* reason */    SC_RAPID_RESET,
+       /* descr */     "http/2 rapid reset detected"
+)
+
+#  undef H2_CUSTOM_ERRORS
+#endif
+
 #undef H2_ERROR
 /*lint -restore */
diff --git a/include/tbl/sess_close.h b/include/tbl/sess_close.h
index c20e71ca6..de130aa87 100644
--- a/include/tbl/sess_close.h
+++ b/include/tbl/sess_close.h
@@ -47,6 +47,7 @@ SESS_CLOSE(PIPE_OVERFLOW, pipe_overflow,1,	"Session pipe overflow")
 SESS_CLOSE(RANGE_SHORT,   range_short,	1,	"Insufficient data for range")
 SESS_CLOSE(REQ_HTTP20,	  req_http20,	1,	"HTTP2 not accepted")
 SESS_CLOSE(VCL_FAILURE,	  vcl_failure,	1,	"VCL failure")
+SESS_CLOSE(RAPID_RESET,	  rapid_reset,  1,      "HTTP2 rapid reset")
 #undef SESS_CLOSE
 
 /*lint -restore */