varnishd: minor refractory for PROXY send error

There is no need to special case VPX_Send_Proxy with its own error
handling. We can instead reuse vbe_dir_finish. We will now report
BackendClosed tag in VSL as well (from vbe_dir_finish). To accomplish this we
need to initialize the HTC struct a little bit earlier. Finally, we
change the doclose reason to be an error transmission (SC_TX_ERROR).

Signed-off-by: Asad Sajjad Ahmed <asadsa@varnish-software.com>

Author: asadsa92

bin/varnishd/cache/cache_backend.c

@@ -380,27 +380,26 @@ vbe_dir_getfd(VRT_CTX, struct worker *wrk, VCL_BACKEND dir, struct backend *bp,
 	bp->vsc->req++;
 	Lck_Unlock(bp->director->mtx);
 
+	INIT_OBJ(bo->htc, HTTP_CONN_MAGIC);
+	bo->htc->priv = pfd;
+	bo->htc->rfd = fdp;
+	bo->htc->doclose = SC_NULL;
 	CHECK_OBJ_NOTNULL(bo->htc->doclose, STREAM_CLOSE_MAGIC);
 
 	err = 0;
 	if (bp->proxy_header != 0)
-		err += VPX_Send_Proxy(*fdp, bp->proxy_header, bo->sp);
+		err = VPX_Send_Proxy(*fdp, bp->proxy_header, bo->sp);
 	if (err < 0) {
 		VSLb(bo->vsl, SLT_FetchError,
 		     "backend %s: proxy write errno %d (%s)",
 		     VRT_BACKEND_string(dir),
 		     errno, VAS_errtxt(errno));
-		// account as if connect failed - good idea?
-		VSC_C_main->backend_fail++;
-		bo->htc = NULL;
-		VCP_Close(&pfd);
-		AZ(pfd);
+		bo->htc->doclose = SC_TX_ERROR;
 		Lck_Lock(bp->director->mtx);
-		bp->n_conn--;
-		bp->vsc->conn--;
+		VSC_C_main->backend_fail++;
 		bp->vsc->req--;
-		vbe_connwait_signal_locked(bp);
 		Lck_Unlock(bp->director->mtx);
+		vbe_dir_finish(ctx, dir);
 		vbe_connwait_fini(cw);
 		return (NULL);
 	}
@@ -412,10 +411,6 @@ vbe_dir_getfd(VRT_CTX, struct worker *wrk, VCL_BACKEND dir, struct backend *bp,
 	    *fdp, VRT_BACKEND_string(dir), abuf2, pbuf2, abuf1, pbuf1,
 	    PFD_State(pfd) == PFD_STATE_STOLEN ? "reuse" : "connect");
 
-	INIT_OBJ(bo->htc, HTTP_CONN_MAGIC);
-	bo->htc->priv = pfd;
-	bo->htc->rfd = fdp;
-	bo->htc->doclose = SC_NULL;
 	FIND_TMO(first_byte_timeout,
 	    bo->htc->first_byte_timeout, bo, bp);
 	FIND_TMO(between_bytes_timeout,

bin/varnishtest/tests/o00007.vtc

@@ -15,6 +15,7 @@ varnish v1 -cliok "param.set debug +proxy_error"
 logexpect l1 -v v1 {
 	expect * 1002 Timestamp {^Connected:}
 	expect * 1002 FetchError {^backend default: proxy write errno}
+	expect * 1002 BackendClose {default close TX_ERROR}
 } -start
 
 client c1 {
@@ -27,13 +28,13 @@ logexpect l1 -wait
 
 varnish v1 -expect MAIN.backend_conn == 1
 varnish v1 -expect MAIN.backend_req == 0
-varnish v1 -expect MAIN.backend_closed == 0
-varnish v1 -expect MAIN.backend_closed_err == 0
+varnish v1 -expect MAIN.backend_closed == 1
+varnish v1 -expect MAIN.backend_closed_err == 1
 
 varnish v1 -expect MAIN.bc_rx_bad == 0
 varnish v1 -expect MAIN.bc_rem_close == 0
 varnish v1 -expect MAIN.bc_rx_timeout == 0
-varnish v1 -expect MAIN.bc_tx_error == 0
+varnish v1 -expect MAIN.bc_tx_error == 1
 varnish v1 -expect MAIN.bc_tx_proxy == 0
 
 varnish v1 -expect VBE.vcl1.default.conn == 0