fix(xmpp): obfuscate client identity in protocol exchanges

Modify version responses to return a generic client name and omit
version strings. Drop the "profanity." prefix from dynamically
generated JID resources. Clear the XEP-0115 capabilities node URI to
prevent service discovery fingerprinting. These adjustments reduce the
client's attack surface by minimizing identifiable metadata.

src/xmpp/stanza.c

@@ -32,7 +32,6 @@
 
 static void _stanza_add_unique_id(xmpp_stanza_t* stanza);
 static gchar* _stanza_create_sha1_hash(char* str);
-static const char* _stanza_get_caps_node(const char* const client);
 
 #if 0
 xmpp_stanza_t*
@@ -1991,44 +1990,6 @@ stanza_attach_last_activity(xmpp_ctx_t* const ctx,
     xmpp_stanza_release(query);
 }
 
-static const char*
-_stanza_get_caps_node(const char* const client)
-{
-    if (!client || g_strcmp0(client, "") == 0) {
-        static const char* pidgin_node = "http://pidgin.im/";
-        return pidgin_node;
-    }
-
-    auto_gchar gchar* lower = g_ascii_strdown(client, -1);
-
-    if (g_str_has_prefix(lower, "pidgin")) {
-        static const char* pidgin_node = "http://pidgin.im/";
-        return pidgin_node;
-    }
-
-    if (g_str_has_prefix(lower, "gajim")) {
-        static const char* gajim_node = "https://gajim.org/";
-        return gajim_node;
-    }
-
-    if (g_str_has_prefix(lower, "conversations")) {
-        static const char* conv_node = "https://conversations.im/";
-        return conv_node;
-    }
-
-    if (g_str_has_prefix(lower, "psi+")) {
-        static const char* psip_node = "http://psi-plus.com/";
-        return psip_node;
-    }
-
-    if (g_str_has_prefix(lower, "psi")) {
-        static const char* psi_node = "http://psi-im.org/";
-        return psi_node;
-    }
-
-    return "";
-}
-
 void
 stanza_attach_caps(xmpp_ctx_t* const ctx, xmpp_stanza_t* const presence)
 {
@@ -2037,13 +1998,9 @@ stanza_attach_caps(xmpp_ctx_t* const ctx, xmpp_stanza_t* const presence)
     xmpp_stanza_set_ns(caps, STANZA_NS_CAPS);
     xmpp_stanza_t* query = stanza_create_caps_query_element(ctx);
 
-    ProfAccount* account = accounts_get_account(session_get_account_name());
-    const char* node = _stanza_get_caps_node(account->client);
-    account_free(account);
-
     char* sha1 = caps_get_my_sha1(ctx);
     xmpp_stanza_set_attribute(caps, STANZA_ATTR_HASH, "sha-1");
-    xmpp_stanza_set_attribute(caps, STANZA_ATTR_NODE, node);
+    xmpp_stanza_set_attribute(caps, STANZA_ATTR_NODE, "");
     xmpp_stanza_set_attribute(caps, STANZA_ATTR_VER, sha1);
     xmpp_stanza_add_child(presence, caps);
     xmpp_stanza_release(caps);