imap: Added support for the STARTTLS capability (Part Two)

Added sending of initial CAPABILITY command before STARTTLS is sent.
This allows for the detection of the capability before trying to
upgrade the connection.

lib/imap.c

@@ -480,14 +480,7 @@ static CURLcode imap_state_capability(struct connectdata *conn)
 
   imapc->authmechs = 0;         /* No known authentication mechanisms yet */
   imapc->authused = 0;          /* Clear the authentication mechanism used */
-
-  /* Check we have a username and password to authenticate with and end the
-     connect phase if we don't */
-  if(!conn->bits.user_passwd) {
-    state(conn, IMAP_STOP);
-
-    return result;
-  }
+  imapc->tls_supported = FALSE; /* Clear the TLS capability */
 
   /* Send the CAPABILITY command */
   result = imap_sendf(conn, "CAPABILITY");
@@ -502,11 +495,19 @@ static CURLcode imap_state_capability(struct connectdata *conn)
 
 static CURLcode imap_state_login(struct connectdata *conn)
 {
-  CURLcode result;
+  CURLcode result = CURLE_OK;
   struct FTP *imap = conn->data->state.proto.imap;
   char *user = imap_atom(imap->user);
   char *passwd = imap_atom(imap->passwd);
 
+  /* Check we have a username and password to authenticate with and end the
+     connect phase if we don't */
+  if(!conn->bits.user_passwd) {
+    state(conn, IMAP_STOP);
+
+    return result;
+  }
+
   /* Send USER and password */
   result = imap_sendf(conn, "LOGIN %s %s", user ? user : "",
                       passwd ? passwd : "");
@@ -532,6 +533,14 @@ static CURLcode imap_authenticate(struct connectdata *conn)
   imapstate state1 = IMAP_STOP;
   imapstate state2 = IMAP_STOP;
 
+  /* Check we have a username and password to authenticate with and end the
+     connect phase if we don't */
+  if(!conn->bits.user_passwd) {
+    state(conn, IMAP_STOP);
+
+    return result;
+  }
+
   /* Calculate the supported authentication mechanism by decreasing order of
      security */
 #ifndef CURL_DISABLE_CRYPTO_AUTH
@@ -644,13 +653,7 @@ static CURLcode imap_state_servergreet_resp(struct connectdata *conn,
     return CURLE_FTP_WEIRD_SERVER_REPLY;
   }
 
-  if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
-    /* We don't have a SSL/TLS connection yet, but SSL is requested. Switch
-       to TLS connection now */
-    result = imap_state_starttls(conn);
-  }
-  else
-    result = imap_state_capability(conn);
+  result = imap_state_capability(conn);
 
   return result;
 }
@@ -671,7 +674,7 @@ static CURLcode imap_state_starttls_resp(struct connectdata *conn,
       result = CURLE_USE_SSL_FAILED;
     }
     else
-      result = imap_state_capability(conn);
+      result = imap_authenticate(conn);
   }
   else
     result = imap_state_upgrade_tls(conn);
@@ -705,13 +708,19 @@ static CURLcode imap_state_capability_resp(struct connectdata *conn,
                                            imapstate instate)
 {
   CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
 
   (void)instate; /* no use for this yet */
 
-  if(imapcode == 'O')
-    result = imap_authenticate(conn);
-  else
+  if(imapcode != 'O')
     result = imap_state_login(conn);
+  else if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
+    /* We don't have a SSL/TLS connection yet, but SSL is requested. Switch
+       to TLS connection now */
+    result = imap_state_starttls(conn);
+  }
+  else
+    result = imap_authenticate(conn);
 
   return result;
 }