Disable weak authentication methods per default

Signed-off-by: Steffen Jaeckel <jaeckel-floss@eyet-services.de>

Author: sjaeckel

src/auth.c

@@ -857,7 +857,8 @@ static void _auth(xmpp_conn_t *conn)
 
         /* SASL algorithm was tried, unset flag */
         conn->sasl_support &= ~scram_ctx->alg->mask;
-    } else if (conn->sasl_support & SASL_MASK_DIGESTMD5) {
+    } else if ((conn->sasl_support & SASL_MASK_DIGESTMD5) &&
+               conn->weak_auth_enabled) {
         auth = _make_sasl_auth(conn, "DIGEST-MD5");
         if (!auth) {
             disconnect_mem_error(conn);
@@ -871,7 +872,8 @@ static void _auth(xmpp_conn_t *conn)
 
         /* SASL DIGEST-MD5 was tried, unset flag */
         conn->sasl_support &= ~SASL_MASK_DIGESTMD5;
-    } else if (conn->sasl_support & SASL_MASK_PLAIN) {
+    } else if ((conn->sasl_support & SASL_MASK_PLAIN) &&
+               conn->weak_auth_enabled) {
         auth = _make_sasl_auth(conn, "PLAIN");
         if (!auth) {
             disconnect_mem_error(conn);

src/common.h

@@ -259,6 +259,7 @@ struct _xmpp_conn_t {
     int sasl_support; /* if true, field is a bitfield of supported
                          mechanisms */
     int auth_legacy_enabled;
+    int weak_auth_enabled;
     int secured; /* set when stream is secured with TLS */
     xmpp_certfail_handler certfail_handler;
     xmpp_password_callback password_callback;

src/conn.c

@@ -1133,6 +1133,7 @@ long xmpp_conn_get_flags(const xmpp_conn_t *conn)
         XMPP_CONN_FLAG_DISABLE_SM * conn->sm_disable |
         XMPP_CONN_FLAG_ENABLE_COMPRESSION * conn->compression.allowed |
         XMPP_CONN_FLAG_COMPRESSION_DONT_RESET * conn->compression.dont_reset |
+        XMPP_CONN_FLAG_WEAK_AUTH * conn->weak_auth_enabled |
         XMPP_CONN_FLAG_LEGACY_AUTH * conn->auth_legacy_enabled;
 
     return flags;
@@ -1188,11 +1189,13 @@ int xmpp_conn_set_flags(xmpp_conn_t *conn, long flags)
         (flags & XMPP_CONN_FLAG_ENABLE_COMPRESSION) ? 1 : 0;
     conn->compression.dont_reset =
         (flags & XMPP_CONN_FLAG_COMPRESSION_DONT_RESET) ? 1 : 0;
-    flags &= ~(XMPP_CONN_FLAG_DISABLE_TLS | XMPP_CONN_FLAG_MANDATORY_TLS |
-               XMPP_CONN_FLAG_LEGACY_SSL | XMPP_CONN_FLAG_TRUST_TLS |
-               XMPP_CONN_FLAG_LEGACY_AUTH | XMPP_CONN_FLAG_DISABLE_SM |
-               XMPP_CONN_FLAG_ENABLE_COMPRESSION |
-               XMPP_CONN_FLAG_COMPRESSION_DONT_RESET);
+    conn->weak_auth_enabled = (flags & XMPP_CONN_FLAG_WEAK_AUTH) ? 1 : 0;
+    flags &=
+        ~(XMPP_CONN_FLAG_DISABLE_TLS | XMPP_CONN_FLAG_MANDATORY_TLS |
+          XMPP_CONN_FLAG_LEGACY_SSL | XMPP_CONN_FLAG_TRUST_TLS |
+          XMPP_CONN_FLAG_LEGACY_AUTH | XMPP_CONN_FLAG_DISABLE_SM |
+          XMPP_CONN_FLAG_ENABLE_COMPRESSION |
+          XMPP_CONN_FLAG_COMPRESSION_DONT_RESET | XMPP_CONN_FLAG_WEAK_AUTH);
     if (flags) {
         strophe_error(conn->ctx, "conn", "Flags 0x%04lx unknown", flags);
         return XMPP_EINVOP;

strophe.h

@@ -208,6 +208,10 @@ typedef struct _xmpp_sm_t xmpp_sm_state_t;
  *  Only enable this flag if you know what you're doing.
  */
 #define XMPP_CONN_FLAG_COMPRESSION_DONT_RESET (1UL << 7)
+/** @def XMPP_CONN_FLAG_WEAK_AUTH
+ *  Allow weak authentication methods (DIGEST-MD5 and PLAIN).
+ */
+#define XMPP_CONN_FLAG_WEAK_AUTH (1UL << 8)
 
 /* connect callback */
 typedef enum {