From 9ada70fab98ee6d8ab0336b6bfe3752e5aad9eb2 Mon Sep 17 00:00:00 2001
From: Armin Becher <armin.becher@de.bosch.com>
Date: Thu, 3 Mar 2022 09:37:57 +0100
Subject: [PATCH] Read response when client closes connection #1232

---
 client.go      | 14 ++++++-------
 client_test.go | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+), 7 deletions(-)

diff --git a/client.go b/client.go
index b36ca40824..9c4f290ffe 100644
--- a/client.go
+++ b/client.go
@@ -13,6 +13,7 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+	"syscall"
 	"time"
 )
 
@@ -1437,12 +1438,11 @@ func (c *HostClient) doNonNilReqResp(req *Request, resp *Response) (bool, error)
 	if err == nil {
 		err = bw.Flush()
 	}
-	if err != nil {
-		c.releaseWriter(bw)
+	c.releaseWriter(bw)
+	if err != nil && !errors.Is(err, syscall.ECONNRESET) {
 		c.closeConn(cc)
 		return true, err
 	}
-	c.releaseWriter(bw)
 
 	if c.ReadTimeout > 0 {
 		// Set Deadline every time, since golang has fixed the performance issue
@@ -1462,14 +1462,14 @@ func (c *HostClient) doNonNilReqResp(req *Request, resp *Response) (bool, error)
 	}
 
 	br := c.acquireReader(conn)
-	if err = resp.ReadLimitBody(br, c.MaxResponseBodySize); err != nil {
-		c.releaseReader(br)
+	err = resp.ReadLimitBody(br, c.MaxResponseBodySize)
+	c.releaseReader(br)
+	if err != nil && !errors.Is(err, syscall.ECONNRESET) {
 		c.closeConn(cc)
 		// Don't retry in case of ErrBodyTooLarge since we will just get the same again.
 		retry := err != ErrBodyTooLarge
 		return retry, err
 	}
-	c.releaseReader(br)
 
 	if resetConnection || req.ConnectionClose() || resp.ConnectionClose() {
 		c.closeConn(cc)
@@ -1477,7 +1477,7 @@ func (c *HostClient) doNonNilReqResp(req *Request, resp *Response) (bool, error)
 		c.releaseConn(cc)
 	}
 
-	return false, err
+	return false, nil
 }
 
 var (
diff --git a/client_test.go b/client_test.go
index 78eda2e58e..aa771c8c5d 100644
--- a/client_test.go
+++ b/client_test.go
@@ -6,7 +6,9 @@ import (
 	"crypto/tls"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"net"
+	"net/http"
 	"net/url"
 	"os"
 	"regexp"
@@ -2840,3 +2842,56 @@ func TestHttpsRequestWithoutParsedURL(t *testing.T) {
 		t.Fatalf("https requests with IsTLS client must succeed")
 	}
 }
+
+// See issue #1232
+func TestRstConnResponseWhileSending(t *testing.T) {
+	const expectedStatus = http.StatusTeapot
+	const payload = "payload"
+
+	srv, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err.Error())
+	}
+
+	go func() {
+		conn, err := srv.Accept()
+		if err != nil {
+			t.Errorf(err.Error())
+		}
+
+		// Read at least one byte of the header
+		// Otherwise we would have an unsolicited response
+		ioutil.ReadAll(io.LimitReader(conn, 1))
+
+		// Respond
+		conn.Write([]byte("HTTP/1.1 418 Teapot\r\n\r\n"))
+
+		// Forcefully close connection
+		err = conn.(*net.TCPConn).SetLinger(0)
+		if err != nil {
+			t.Errorf(err.Error())
+		}
+		conn.Close()
+	}()
+
+	svrUrl := "http://" + srv.Addr().String()
+
+	client := HostClient{Addr: srv.Addr().String()}
+
+	req := AcquireRequest()
+	defer ReleaseRequest(req)
+	resp := AcquireResponse()
+	defer ReleaseResponse(resp)
+
+	req.Header.SetMethod("POST")
+	req.SetBodyStream(strings.NewReader(payload), len(payload))
+	req.SetRequestURI(svrUrl)
+
+	err = client.Do(req, resp)
+	if err != nil {
+		t.Fatal(err.Error())
+	}
+	if expectedStatus != resp.StatusCode() {
+		t.Fatalf("Expected %d status code, but got %d", expectedStatus, resp.StatusCode())
+	}
+}