Add support for managed HTTP/S transports (#810)

This change uses the newly-exposed Transport interface to use Go's
implementation of http.Client instead of httpclient via libgit2.

1 files changed, 241 insertions, 0 deletions

diff --git a/http.go b/http.go
new file mode 100644
index 0000000..0777c56
--- /dev/null
+++ b/http.go
@@ -0,0 +1,241 @@
+package git
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"sync"
+)
+
+// RegisterManagedHTTPTransport registers a Go-native implementation of an
+// HTTP/S transport that doesn't rely on any system libraries (e.g.
+// libopenssl/libmbedtls).
+//
+// If Shutdown or ReInit are called, make sure that the smart transports are
+// freed before it.
+func RegisterManagedHTTPTransport(protocol string) (*RegisteredSmartTransport, error) {
+	return NewRegisteredSmartTransport(protocol, true, httpSmartSubtransportFactory)
+}
+
+func registerManagedHTTP() error {
+	globalRegisteredSmartTransports.Lock()
+	defer globalRegisteredSmartTransports.Unlock()
+
+	for _, protocol := range []string{"http", "https"} {
+		if _, ok := globalRegisteredSmartTransports.transports[protocol]; ok {
+			continue
+		}
+		managed, err := newRegisteredSmartTransport(protocol, true, httpSmartSubtransportFactory, true)
+		if err != nil {
+			return fmt.Errorf("failed to register transport for %q: %v", protocol, err)
+		}
+		globalRegisteredSmartTransports.transports[protocol] = managed
+	}
+	return nil
+}
+
+func httpSmartSubtransportFactory(remote *Remote, transport *Transport) (SmartSubtransport, error) {
+	var proxyFn func(*http.Request) (*url.URL, error)
+	proxyOpts, err := transport.SmartProxyOptions()
+	if err != nil {
+		return nil, err
+	}
+	switch proxyOpts.Type {
+	case ProxyTypeNone:
+		proxyFn = nil
+	case ProxyTypeAuto:
+		proxyFn = http.ProxyFromEnvironment
+	case ProxyTypeSpecified:
+		parsedUrl, err := url.Parse(proxyOpts.Url)
+		if err != nil {
+			return nil, err
+		}
+
+		proxyFn = http.ProxyURL(parsedUrl)
+	}
+
+	return &httpSmartSubtransport{
+		transport: transport,
+		client: &http.Client{
+			Transport: &http.Transport{
+				Proxy: proxyFn,
+			},
+		},
+	}, nil
+}
+
+type httpSmartSubtransport struct {
+	transport *Transport
+	client    *http.Client
+}
+
+func (t *httpSmartSubtransport) Action(url string, action SmartServiceAction) (SmartSubtransportStream, error) {
+	var req *http.Request
+	var err error
+	switch action {
+	case SmartServiceActionUploadpackLs:
+		req, err = http.NewRequest("GET", url+"/info/refs?service=git-upload-pack", nil)
+
+	case SmartServiceActionUploadpack:
+		req, err = http.NewRequest("POST", url+"/git-upload-pack", nil)
+		if err != nil {
+			break
+		}
+		req.Header.Set("Content-Type", "application/x-git-upload-pack-request")
+
+	case SmartServiceActionReceivepackLs:
+		req, err = http.NewRequest("GET", url+"/info/refs?service=git-receive-pack", nil)
+
+	case SmartServiceActionReceivepack:
+		req, err = http.NewRequest("POST", url+"/info/refs?service=git-upload-pack", nil)
+		if err != nil {
+			break
+		}
+		req.Header.Set("Content-Type", "application/x-git-receive-pack-request")
+
+	default:
+		err = errors.New("unknown action")
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("User-Agent", "git/2.0 (git2go)")
+
+	stream := newManagedHttpStream(t, req)
+	if req.Method == "POST" {
+		stream.recvReply.Add(1)
+		stream.sendRequestBackground()
+	}
+
+	return stream, nil
+}
+
+func (t *httpSmartSubtransport) Close() error {
+	return nil
+}
+
+func (t *httpSmartSubtransport) Free() {
+	t.client = nil
+}
+
+type httpSmartSubtransportStream struct {
+	owner       *httpSmartSubtransport
+	req         *http.Request
+	resp        *http.Response
+	reader      *io.PipeReader
+	writer      *io.PipeWriter
+	sentRequest bool
+	recvReply   sync.WaitGroup
+	httpError   error
+}
+
+func newManagedHttpStream(owner *httpSmartSubtransport, req *http.Request) *httpSmartSubtransportStream {
+	r, w := io.Pipe()
+	return &httpSmartSubtransportStream{
+		owner:  owner,
+		req:    req,
+		reader: r,
+		writer: w,
+	}
+}
+
+func (self *httpSmartSubtransportStream) Read(buf []byte) (int, error) {
+	if !self.sentRequest {
+		self.recvReply.Add(1)
+		if err := self.sendRequest(); err != nil {
+			return 0, err
+		}
+	}
+
+	if err := self.writer.Close(); err != nil {
+		return 0, err
+	}
+
+	self.recvReply.Wait()
+
+	if self.httpError != nil {
+		return 0, self.httpError
+	}
+
+	return self.resp.Body.Read(buf)
+}
+
+func (self *httpSmartSubtransportStream) Write(buf []byte) (int, error) {
+	if self.httpError != nil {
+		return 0, self.httpError
+	}
+	return self.writer.Write(buf)
+}
+
+func (self *httpSmartSubtransportStream) Free() {
+	if self.resp != nil {
+		self.resp.Body.Close()
+	}
+}
+
+func (self *httpSmartSubtransportStream) sendRequestBackground() {
+	go func() {
+		self.httpError = self.sendRequest()
+	}()
+	self.sentRequest = true
+}
+
+func (self *httpSmartSubtransportStream) sendRequest() error {
+	defer self.recvReply.Done()
+	self.resp = nil
+
+	var resp *http.Response
+	var err error
+	var userName string
+	var password string
+	for {
+		req := &http.Request{
+			Method: self.req.Method,
+			URL:    self.req.URL,
+			Header: self.req.Header,
+		}
+		if req.Method == "POST" {
+			req.Body = self.reader
+			req.ContentLength = -1
+		}
+
+		req.SetBasicAuth(userName, password)
+		resp, err = http.DefaultClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		if resp.StatusCode == http.StatusOK {
+			break
+		}
+
+		if resp.StatusCode == http.StatusUnauthorized {
+			resp.Body.Close()
+
+			cred, err := self.owner.transport.SmartCredentials("", CredentialTypeUserpassPlaintext)
+			if err != nil {
+				return err
+			}
+			defer cred.Free()
+
+			userName, password, err = cred.GetUserpassPlaintext()
+			if err != nil {
+				return err
+			}
+
+			continue
+		}
+
+		// Any other error we treat as a hard error and punt back to the caller
+		resp.Body.Close()
+		return fmt.Errorf("Unhandled HTTP error %s", resp.Status)
+	}
+
+	self.sentRequest = true
+	self.resp = resp
+	return nil
+}