From 8838dde116abfd09d74ffee208a6ae6f8002a900 Mon Sep 17 00:00:00 2001
From: Jonathan Harris <jonathan@marginal.org.uk>
Date: Fri, 18 Jan 2019 13:21:51 +0000
Subject: [PATCH] More robust handling of cAPI server errors

---
 EDMarketConnector.py |  4 ++--
 companion.py         | 20 +++++++++++++++-----
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/EDMarketConnector.py b/EDMarketConnector.py
index f51511be..ef099ae3 100755
--- a/EDMarketConnector.py
+++ b/EDMarketConnector.py
@@ -468,7 +468,7 @@ class AppWindow:
                 self.holdofftime = querytime + companion.holdoff
 
         # Companion API problem
-        except (companion.ServerError, companion.ServerLagging) as e:
+        except companion.ServerLagging as e:
             if retrying:
                 self.status['text'] = unicode(e)
                 play_bad = True
@@ -483,7 +483,7 @@ class AppWindow:
             companion.session.invalidate()
             self.login()
 
-        except Exception as e:
+        except Exception as e:			# Including CredentialsError, ServerError
             if __debug__: print_exc()
             self.status['text'] = unicode(e)
             play_bad = True
diff --git a/companion.py b/companion.py
index e4cda4d8..df3a6b47 100644
--- a/companion.py
+++ b/companion.py
@@ -271,6 +271,7 @@ class Session:
         self.credentials = None
         self.session = None
         self.auth = None
+        self.retrying = False	# Avoid infinite loop when successful auth / unsuccessful query
 
         # yuck suppress InsecurePlatformWarning under Python < 2.7.9 which lacks SNI support
         if sys.version_info < (2,7,9):
@@ -343,10 +344,11 @@ class Session:
             if __debug__: print_exc()
             raise ServerError()
 
-        if 400 <= r.status_code < 500 or r.url.startswith(SERVER_AUTH):
-           # Client error or redirected back to Auth server - force full re-authentication
+        if r.url.startswith(SERVER_AUTH):
+            # Redirected back to Auth server - force full re-authentication
             self.dump(r)
             self.invalidate()
+            self.retrying = False
             self.login()
             raise CredentialsError()
         elif 500 <= r.status_code < 600:
@@ -355,16 +357,24 @@ class Session:
             raise ServerError()
 
         try:
-            data = r.json()	# Will fail here if token expired since response is empty
+            r.raise_for_status()	# Typically 403 "Forbidden" on token expiry
+            data = r.json()		# May also fail here if token expired since response is empty
         except:
-            # Start again - maybe our token expired
             self.dump(r)
             self.close()
-            if self.login():
+            if self.retrying:		# Refresh just succeeded but this query failed! Force full re-authentication
+                self.invalidate()
+                self.retrying = False
+                self.login()
+                raise CredentialsError()
+            elif self.login():		# Maybe our token expired. Re-authorize in any case
+                self.retrying = True
                 return self.query(endpoint)
             else:
+                self.retrying = False
                 raise CredentialsError()
 
+        self.retrying = False
         if 'timestamp' not in data:
             data['timestamp'] = time.strftime('%Y-%m-%dT%H:%M:%SZ', parsedate(r.headers['Date']))
         return data