reverseproxy: Rewrite request buffering for fastcgi

modules/caddyhttp/reverseproxy/fastcgi/caddyfile.go

@@ -19,6 +19,8 @@ import (
 	"net/http"
 	"strconv"
 
+	"github.com/dustin/go-humanize"
+
 	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig"
 	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
@@ -43,7 +45,10 @@ func init() {
 //	    dial_timeout <duration>
 //	    read_timeout <duration>
 //	    write_timeout <duration>
-//	    capture_stderr
+//	    body_buffer_disabled
+//	    body_buffer_memory_limit <size>
+//	    file_buffer_size_limit <size>
+//	    file_buffer_filepath <path>
 //	}
 func (t *Transport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 	d.Next() // consume transport name
@@ -113,6 +118,35 @@ func (t *Transport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
 			}
 			t.CaptureStderr = true
 
+		case "body_buffer_disabled":
+			t.BodyBufferDisabled = true
+
+		case "body_buffer_memory_limit":
+			if !d.NextArg() {
+				return d.ArgErr()
+			}
+			size, err := humanize.ParseBytes(d.Val())
+			if err != nil {
+				return d.Errf("bad buffer size %s: %v", d.Val(), err)
+			}
+			t.BodyBufferMemoryLimit = int64(size)
+
+		case "file_buffer_size_limit":
+			if !d.NextArg() {
+				return d.ArgErr()
+			}
+			size, err := humanize.ParseBytes(d.Val())
+			if err != nil {
+				return d.Errf("bad buffer size %s: %v", d.Val(), err)
+			}
+			t.FileBufferSizeLimit = int64(size)
+
+		case "file_buffer_filepath":
+			if !d.NextArg() {
+				return d.ArgErr()
+			}
+			t.FileBufferFilepath = d.Val()
+
 		default:
 			return d.Errf("unrecognized subdirective %s", d.Val())
 		}
@@ -294,6 +328,40 @@ func parsePHPFastCGI(h httpcaddyfile.Helper) ([]httpcaddyfile.ConfigValue, error
 				args := dispenser.RemainingArgs()
 				dispenser.DeleteN(len(args) + 1)
 				fcgiTransport.CaptureStderr = true
+
+			case "body_buffer_disabled":
+				args := dispenser.RemainingArgs()
+				dispenser.DeleteN(len(args) + 1)
+				fcgiTransport.BodyBufferDisabled = true
+
+			case "body_buffer_memory_limit":
+				if !dispenser.NextArg() {
+					return nil, dispenser.ArgErr()
+				}
+				size, err := humanize.ParseBytes(dispenser.Val())
+				if err != nil {
+					return nil, dispenser.Errf("bad buffer size %s: %v", dispenser.Val(), err)
+				}
+				fcgiTransport.BodyBufferMemoryLimit = int64(size)
+				dispenser.DeleteN(2)
+
+			case "file_buffer_size_limit":
+				if !dispenser.NextArg() {
+					return nil, dispenser.ArgErr()
+				}
+				size, err := humanize.ParseBytes(dispenser.Val())
+				if err != nil {
+					return nil, dispenser.Errf("bad buffer size %s: %v", dispenser.Val(), err)
+				}
+				fcgiTransport.FileBufferSizeLimit = int64(size)
+				dispenser.DeleteN(2)
+
+			case "file_buffer_filepath":
+				if !dispenser.NextArg() {
+					return nil, dispenser.ArgErr()
+				}
+				fcgiTransport.FileBufferFilepath = dispenser.Val()
+				dispenser.DeleteN(2)
 			}
 		}
 	}

modules/caddyhttp/reverseproxy/fastcgi/client.go

@@ -128,9 +128,11 @@ var pad [maxPad]byte
 type client struct {
 	rwc net.Conn
 	// keepAlive bool // TODO: implement
-	reqID  uint16
-	stderr bool
-	logger *zap.Logger
+	reqID      uint16
+	stderr     bool
+	logger     *zap.Logger
+	buffer     bool
+	bufferFunc func(io.Reader) (int64, io.ReadCloser, error)
 }
 
 // Do made the request and returns a io.Reader that translates the data read
@@ -158,6 +160,10 @@ func (c *client) Do(p map[string]string, req io.Reader) (r io.Reader, err error)
 		if err != nil {
 			return nil, err
 		}
+		// body length mismatch
+		if lr, ok := req.(*io.LimitedReader); ok && lr.N > 0 {
+			return nil, io.ErrUnexpectedEOF
+		}
 	}
 	err = writer.FlushStream()
 	if err != nil {
@@ -197,9 +203,68 @@ func (f clientCloser) Close() error {
 	return f.rwc.Close()
 }
 
+// create a response that describes the error message, it's passed to the client.
+// caller should close the connection to fastcgi server
+func newErrorResponse(status int) *http.Response {
+	statusText := http.StatusText(status)
+	resp := &http.Response{
+		Status:        statusText,
+		StatusCode:    status,
+		Header:        make(http.Header),
+		Body:          io.NopCloser(strings.NewReader(statusText)),
+		ContentLength: int64(len(statusText)),
+	}
+	resp.Header.Set("Content-Length", strconv.FormatInt(resp.ContentLength, 10))
+	resp.Header.Set("Content-Type", "text/plain; charset=utf-8")
+	resp.Header.Set("X-Content-Type-Options", "nosniff")
+	return resp
+}
+
+// check for invalid content_length to determine if the request should be buffered
+func checkContentLength(p map[string]string) (int64, bool) {
+	clStr, ok := p["CONTENT_LENGTH"]
+	if !ok {
+		return 0, false
+	}
+	cl, err := strconv.ParseInt(clStr, 10, 64)
+	if err != nil || cl < 0 {
+		return 0, false
+	}
+	return cl, true
+}
+
 // Request returns a HTTP Response with Header and Body
 // from fcgi responder
 func (c *client) Request(p map[string]string, req io.Reader) (resp *http.Response, err error) {
+	// defer closing the request body if it's an io.Closer
+	if closer, ok := req.(io.Closer); ok {
+		defer closer.Close()
+	}
+
+	// check for content_length and buffer the request if needed
+	cl, ok := checkContentLength(p)
+	if !ok {
+		// buffering disabled
+		if !c.buffer {
+			c.rwc.Close()
+			return newErrorResponse(http.StatusLengthRequired), nil
+		} else {
+			// buffer the request
+			size, rc, err := c.bufferFunc(req)
+			if err != nil {
+				if err == errFileBufferExceeded {
+					c.rwc.Close()
+					return newErrorResponse(http.StatusRequestEntityTooLarge), nil
+				}
+				return nil, err
+			}
+			defer rc.Close()
+			p["CONTENT_LENGTH"] = strconv.FormatInt(size, 10)
+		}
+	} else {
+		req = io.LimitReader(req, cl)
+	}
+
 	r, err := c.Do(p, req)
 	if err != nil {
 		return
@@ -302,7 +367,7 @@ func (c *client) Post(p map[string]string, method string, bodyType string, body
 // PostForm issues a POST to the fcgi responder, with form
 // as a string key to a list values (url.Values)
 func (c *client) PostForm(p map[string]string, data url.Values) (resp *http.Response, err error) {
-	body := bytes.NewReader([]byte(data.Encode()))
+	body := strings.NewReader(data.Encode())
 	return c.Post(p, "POST", "application/x-www-form-urlencoded", body, int64(body.Len()))
 }