From fce5997fda8847b04689d7d5684d9a4792bd654c Mon Sep 17 00:00:00 2001
From: seborama <sebastien.chatal@sainsburys.co.uk>
Date: Sat, 10 Sep 2016 02:09:21 +0100
Subject: [PATCH] [Fixes] Fixes & improvements

---
 govcr.go | 41 +++++++++++++++++++++++++++++------------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/govcr.go b/govcr.go
index 430b663..621613d 100644
--- a/govcr.go
+++ b/govcr.go
@@ -7,6 +7,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"strings"
 )
 
 // VCRControlPanel holds the parts of a VCR that can be interacted with.
@@ -92,11 +93,10 @@ func (pcbr *pcb) trackMatches(cassette *cassette, trackNumber int, req *http.Req
 
 // headerResembles compares HTTP headers for equivalence.
 func (pcbr *pcb) headerResembles(header1 http.Header, header2 http.Header) bool {
-	for k, v1 := range header1 {
-		for _, v2 := range v1 {
-			if header2.Get(k) != v2 && !pcbr.ExcludeHeaderFunc(k) {
-				return false
-			}
+	for k := range header1 {
+		// TODO: a given header may have several values (and in any order)
+		if GetFirstValue(header1, k) != GetFirstValue(header2, k) && !pcbr.ExcludeHeaderFunc(k) {
+			return false
 		}
 	}
 
@@ -110,8 +110,8 @@ func (pcbr *pcb) bodyResembles(body1 string, body2 string) bool {
 	return *pcbr.RequestBodyFilterFunc(body1) == *pcbr.RequestBodyFilterFunc(body2)
 }
 
-func (pcbr *pcb) filterHeader(resp *http.Response) *http.Response {
-	resp.Header = *pcbr.ResponseHeaderFilterFunc(resp.Header)
+func (pcbr *pcb) filterHeader(resp *http.Response, reqHdr http.Header) *http.Response {
+	resp.Header = *pcbr.ResponseHeaderFilterFunc(resp.Header, reqHdr)
 	return resp
 }
 
@@ -127,6 +127,22 @@ func (pcbr *pcb) filterBody(resp *http.Response) *http.Response {
 	return resp
 }
 
+// GetFirstValue is a utility function that extracts the first value of a header key.
+// The reason for this function is that some servers require case sensitive headers which
+// prevent the use of http.Header.Get() as it expects header keys to be canonicalized.
+func GetFirstValue(hdr http.Header, key string) string {
+	for k, val := range hdr {
+		if strings.ToLower(k) == strings.ToLower(key) {
+			if len(val) > 0 {
+				return val[0]
+			}
+			return ""
+		}
+	}
+
+	return ""
+}
+
 // NewVCR creates a new VCR and loads a cassette.
 // A RoundTripper can be provided when a custom Transport is needed (for example to provide
 // certificates, etc)
@@ -155,7 +171,7 @@ func NewVCR(cassetteName string, vcrConfig *VCRConfig) *VCRControlPanel {
 	// use a default set of FilterFunc's
 	if vcrConfig.ExcludeHeaderFunc == nil {
 		vcrConfig.ExcludeHeaderFunc = func(key string) bool {
-			return true
+			return false
 		}
 	}
 
@@ -166,8 +182,8 @@ func NewVCR(cassetteName string, vcrConfig *VCRConfig) *VCRControlPanel {
 	}
 
 	if vcrConfig.ResponseHeaderFilterFunc == nil {
-		vcrConfig.ResponseHeaderFilterFunc = func(header http.Header) *http.Header {
-			return &header
+		vcrConfig.ResponseHeaderFilterFunc = func(respHdr http.Header, reqHdr http.Header) *http.Header {
+			return &respHdr
 		}
 	}
 
@@ -239,7 +255,7 @@ type BodyFilterFunc func(string) *string
 //
 // It is important to note that this differs from ExcludeHeaderFunc in that the former does not
 // modify the header (it only returns a bool) whereas this function can be used to modify the header.
-type HeaderFilterFunc func(header http.Header) *http.Header
+type HeaderFilterFunc func(http.Header, http.Header) *http.Header
 
 // vcrTransport is the heart of VCR. It provides
 // an http.RoundTripper that wraps over the default
@@ -272,7 +288,8 @@ func (t *vcrTransport) RoundTrip(req *http.Request) (*http.Response, error) {
 	// attempt to use a track from the cassette that matches
 	// the request if one exists.
 	if trackNumber := t.PCB.seekTrack(t.Cassette, copiedReq); trackNumber != trackNotFound {
-		resp = t.PCB.filterHeader(t.PCB.filterBody(t.Cassette.replayResponse(trackNumber, copiedReq)))
+		// only the played back response is filtered. Never the live response!
+		resp = t.PCB.filterHeader(t.PCB.filterBody(t.Cassette.replayResponse(trackNumber, copiedReq)), copiedReq.Header)
 		requestMatched = true
 	}