Add Hack for Discover

Discover requires an exact set of headers in exact order, or it returns
HTTP 403.

client.go

@@ -63,6 +63,7 @@ func GetClient(URL string, bc *BasicClient) Client {
 		URL  string
 		Func clientCreationFunc
 	}{
+		{"https://ofx.discovercard.com", NewDiscoverCardClient},
 		{"https://vesnc.vanguard.com/us/OfxDirectConnectServlet", NewVanguardClient},
 	}
 	for _, client := range clients {

discovercard_client.go

@@ -0,0 +1,103 @@
+package ofxgo
+
+import (
+	"bufio"
+	"bytes"
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+// DiscoverCardClient provides a Client implementation which handles
+// DiscoverCard's broken HTTP header behavior. DiscoverCardClient uses default,
+// non-zero settings, if its fields are not initialized.
+type DiscoverCardClient struct {
+	*BasicClient
+}
+
+// NewDiscoverCardClient returns a Client interface configured to handle
+// Discover Card's brand of idiosyncracy
+func NewDiscoverCardClient(bc *BasicClient) Client {
+	return &DiscoverCardClient{bc}
+}
+
+func discoverCardHTTPPost(URL string, r io.Reader) (*http.Response, error) {
+	// Either convert or copy to a bytes.Buffer to be able to determine the
+	// request length for the Content-Length header
+	buf, ok := r.(*bytes.Buffer)
+	if !ok {
+		buf = &bytes.Buffer{}
+		_, err := io.Copy(buf, r)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	url, err := url.Parse(URL)
+	if err != nil {
+		return nil, err
+	}
+
+	path := url.Path
+	if path == "" {
+		path = "/"
+	}
+
+	// Discover requires only these headers and in this exact order, or it
+	// returns HTTP 403
+	headers := fmt.Sprintf("POST %s HTTP/1.1\r\n"+
+		"Content-Type: application/x-ofx\r\n"+
+		"Host: %s\r\n"+
+		"Content-Length: %d\r\n"+
+		"Connection: Keep-Alive\r\n"+
+		"\r\n", path, url.Hostname(), buf.Len())
+
+	host := url.Host
+	if url.Port() == "" {
+		host += ":443"
+	}
+
+	// BUGBUG: cannot do defer conn.Close() until body is read,
+	// we are "leaking" a socket here, but it will be finalized
+	conn, err := tls.Dial("tcp", host, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	fmt.Fprint(conn, headers)
+	_, err = io.Copy(conn, buf)
+	if err != nil {
+		return nil, err
+	}
+
+	return http.ReadResponse(bufio.NewReader(conn), nil)
+}
+
+func (c *DiscoverCardClient) RawRequest(URL string, r io.Reader) (*http.Response, error) {
+	if !strings.HasPrefix(URL, "https://") {
+		return nil, errors.New("Refusing to send OFX request with possible plain-text password over non-https protocol")
+	}
+
+	response, err := discoverCardHTTPPost(URL, r)
+	if err != nil {
+		return nil, err
+	}
+
+	if response.StatusCode != 200 {
+		return nil, errors.New("OFXQuery request status: " + response.Status)
+	}
+
+	return response, nil
+}
+
+func (c *DiscoverCardClient) RequestNoParse(r *Request) (*http.Response, error) {
+	return clientRequestNoParse(c, r)
+}
+
+func (c *DiscoverCardClient) Request(r *Request) (*Response, error) {
+	return clientRequest(c, r)
+}