pop3: Added support for the STLS capability (Part Two)

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

lib/pop3.c

@@ -393,14 +393,7 @@ static CURLcode pop3_state_capa(struct connectdata *conn)
 
   pop3c->authmechs = 0;         /* No known authentication mechanisms yet */
   pop3c->authused = 0;          /* Clear the authentication mechanism used */
-
+  pop3c->tls_supported = FALSE; /* Clear the TLS capability */
-  /* 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, POP3_STOP);
-
-    return result;
-  }
 
   /* Send the CAPA command */
   result = Curl_pp_sendf(&pop3c->pp, "CAPA");
@@ -415,9 +408,17 @@ static CURLcode pop3_state_capa(struct connectdata *conn)
 
 static CURLcode pop3_state_user(struct connectdata *conn)
 {
-  CURLcode result;
+  CURLcode result = CURLE_OK;
   struct FTP *pop3 = conn->data->state.proto.pop3;
 
+  /* 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, POP3_STOP);
+
+    return result;
+  }
+
   /* Send the USER command */
   result = Curl_pp_sendf(&conn->proto.pop3c.pp, "USER %s",
                          pop3->user ? pop3->user : "");
@@ -439,6 +440,15 @@ static CURLcode pop3_state_apop(struct connectdata *conn)
   unsigned char digest[MD5_DIGEST_LEN];
   char secret[2 * MD5_DIGEST_LEN + 1];
 
+  /* 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, POP3_STOP);
+
+    return result;
+  }
+
+  /* Create the digest */
   ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
   if(!ctxt)
     return CURLE_OUT_OF_MEMORY;
@@ -472,6 +482,14 @@ static CURLcode pop3_authenticate(struct connectdata *conn)
   const char *mech = NULL;
   pop3state authstate = POP3_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, POP3_STOP);
+
+    return result;
+  }
+
   /* Calculate the supported authentication mechanism by decreasing order of
      security */
   if(pop3c->authtypes & POP3_TYPE_SASL) {
@@ -563,13 +581,7 @@ static CURLcode pop3_state_servergreet_resp(struct connectdata *conn,
     return CURLE_FTP_WEIRD_SERVER_REPLY;
   }
 
-  if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
+  result = pop3_state_capa(conn);
-    /* We don't have a SSL/TLS connection yet, but SSL is requested. Switch
-       to TLS connection now */
-    result = pop3_state_starttls(conn);
-  }
-  else
-    result = pop3_state_capa(conn);
 
   return result;
 }
@@ -590,7 +602,7 @@ static CURLcode pop3_state_starttls_resp(struct connectdata *conn,
       result = CURLE_USE_SSL_FAILED;
     }
     else
-      result = pop3_state_capa(conn);
+      result = pop3_authenticate(conn);
   }
   else
     result = pop3_state_upgrade_tls(conn);
@@ -623,13 +635,19 @@ static CURLcode pop3_state_capa_resp(struct connectdata *conn, int pop3code,
                                      pop3state instate)
 {
   CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
 
   (void)instate; /* no use for this yet */
 
-  if(pop3code == '+')
+  if(pop3code != '+')
-    result = pop3_authenticate(conn);
-  else
     result = pop3_state_user(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 = pop3_state_starttls(conn);
+  }
+  else
+    result = pop3_authenticate(conn);
 
   return result;
 }