Add ability to set the request headers

[fire]

Hi, was wondering to add the ability to set request headers:

httpkit/htfs/conn.go

Line 115 in 50f60be

func (c *conn) tryConnect(offset int64) error {

For example the external site expects some headers and rejects all requests without it.

The actual use-case is setting a cookie.

[fire]

func (c *conn) tryConnect(offset int64) error {
	hf := c.file

	req, err := http.NewRequest("GET", hf.currentURL, nil)
	if err != nil {
		return err
	}

        key := os.Getenv("EXAMPLE_API_KEY") //change
        req.Header.Set("Cookie", "example=" + key) //change

	byteRange := fmt.Sprintf("bytes=%d-", offset)
	req.Header.Set("Range", byteRange)

	res, err := hf.client.Do(req)
	if err != nil {
		return err
	}

This is what I got.

[fasterthanlime]

The way I'd go about it would be to add a

ModifyRequest func (req *http.Request)

in htfs.Settings:

httpkit/htfs/file.go

Lines 114 to 122 in a507e90

	// Settings allows passing additional settings to an File
	type Settings struct {
	Client *http.Client
	RetrySettings *retrycontext.Settings
	Log LogFunc
	LogLevel int
	ForbidBacktracking bool
	DumpStats bool
	}

Then File would be responsible to pass it down to conn, which would call it in tryConnect (if it's non-nil).

Do you want to give it a shot?

[fire]

This seems better. Can push it down the chain more, but wanted review.

diff --git a/vendor/github.com/itchio/httpkit/htfs/conn.go b/vendor/github.com/itchio/httpkit/htfs/conn.go
index 9cfbed7..1ae66d1 100644
--- a/vendor/github.com/itchio/httpkit/htfs/conn.go
+++ b/vendor/github.com/itchio/httpkit/htfs/conn.go
@@ -24,6 +24,7 @@ type conn struct {
 	currentURL string
 
 	header        http.Header
+	modifyRequest func (req *http.Request)
 	requestURL    *url.URL
 	statusCode    int
 	contentLength int64
@@ -120,6 +121,10 @@ func (c *conn) tryConnect(offset int64) error {
 		return err
 	}
 
+	if hf.modifyRequest != nil {
+		hf.modifyRequest(req)
+	}	
+
 	byteRange := fmt.Sprintf("bytes=%d-", offset)
 	req.Header.Set("Range", byteRange)
 
diff --git a/vendor/github.com/itchio/httpkit/htfs/file.go b/vendor/github.com/itchio/httpkit/htfs/file.go
index caa7fb6..e105d0d 100644
--- a/vendor/github.com/itchio/httpkit/htfs/file.go
+++ b/vendor/github.com/itchio/httpkit/htfs/file.go
@@ -72,6 +72,7 @@ type File struct {
 	getURL        GetURLFunc
 	needsRenewal  NeedsRenewalFunc
 	client        *http.Client
+	modifyRequest func (req *http.Request)
 	retrySettings *retrycontext.Settings
 
 	Log      LogFunc
@@ -114,6 +115,7 @@ var _ io.Closer = (*File)(nil)
 // Settings allows passing additional settings to an File
 type Settings struct {
 	Client             *http.Client
+	ModifyRequest      func (req *http.Request)
 	RetrySettings      *retrycontext.Settings
 	Log                LogFunc
 	LogLevel           int
@@ -139,6 +141,7 @@ func Open(getURL GetURLFunc, needsRenewal NeedsRenewalFunc, settings *Settings)
 		retrySettings: &retryCtx.Settings,
 		needsRenewal:  needsRenewal,
 		client:        client,
+		modifyRequest: settings.ModifyRequest,
 		name:          "<remote file>",
 
 		conns: make(map[string]*conn),
diff --git a/vendor/github.com/itchio/wharf/eos/eos.go b/vendor/github.com/itchio/wharf/eos/eos.go
index 44f5a21..820c290 100644
--- a/vendor/github.com/itchio/wharf/eos/eos.go
+++ b/vendor/github.com/itchio/wharf/eos/eos.go
@@ -136,7 +136,15 @@ func realOpen(name string, opts ...option.Option) (File, error) {
 	switch u.Scheme {
 	case "http", "https":
 		res := &simpleHTTPResource{name}
-		hf, err := htfs.Open(res.GetURL, res.NeedsRenewal, htfsSettings())
+
+	   	key := os.Getenv("EXAMPLE_API_KEY")
+
+		settings := htfsSettings()
+		settings.ModifyRequest = func (req *http.Request) {
+        		req.Header.Set("Cookie", "example=" + key)
+    		}
+
+		hf, err := htfs.Open(res.GetURL, res.NeedsRenewal, settings)
 
 		if err != nil {
 			return nil, err