Begin implementing SFTP server code

api/sftp_endpoints.go

@@ -0,0 +1,39 @@
+package api
+
+import (
+	"encoding/json"
+	"github.com/pkg/errors"
+	"github.com/pterodactyl/sftp-server"
+)
+
+func (r *PanelRequest) ValidateSftpCredentials(request sftp_server.AuthenticationRequest) (*sftp_server.AuthenticationResponse, error) {
+	b, err := json.Marshal(request)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := r.Post("/sftp/auth/login", b)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	r.Response = resp
+
+	if r.HasError() {
+		if r.HttpResponseCode() == 403 {
+			return nil, sftp_server.InvalidCredentialsError{}
+		}
+
+		return nil, errors.WithStack(errors.New(r.Error()))
+	}
+
+	response := new(sftp_server.AuthenticationResponse)
+	body, _ := r.ReadBody()
+
+	if err := json.Unmarshal(body, response); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}