fix: CWE-134 format string audit and compiler hardening

Security:
Fix CWE-134 in iq.c: user-controlled string passed as format argument
Add G_GNUC_PRINTF annotations to all variadic printf-like wrappers
in ui.h, log.h and http_common.h
Compiler flags (configure.ac):

Replace basic -Wformat/-Wformat-nonliteral with -Wformat=2
Add -Wextra, -Wnull-dereference, -Wpointer-arith,
-Wimplicit-function-declaration, -Wundef, -Wfloat-equal,
-Wredundant-decls, -Walloc-zero
Add -fstack-protector-strong, -fno-common, -D_FORTIFY_SOURCE=2
Add GCC-specific flags via AC_COMPILE_IFELSE: -Wlogical-op,
-Wduplicated-cond, -Wduplicated-branches, -Wstringop-overflow,
-Warray-bounds=2
Suppress noisy -Wextra sub-warnings: -Wno-unused-parameter,
-Wno-missing-field-initializers, -Wno-sign-compare,
-Wno-cast-function-type
Remove AM_CFLAGS/CFLAGS duplication
Bug fixes found by new warnings:

chatlog.c: non-MUCPM redact path passed resourcepart instead of NULL
rosterwin.c: merge duplicated if/else branches into single condition
omemo.c: redundant else-if in omemo_automatic_start; remove
unnecessary scope block and goto, use early return
console.c: pointer compared to integer 0 instead of NULL
stanza.c: increase pri_str/idle_str buffers from 10 to 12 bytes
(INT_MIN = -2147483648 needs 12 bytes including NUL)
vcard.c: NULL guard for filename before g_file_set_contents
api.c: broken log_warning() calls with extra format argument
Format mismatch fixes:

chatwin.c: Jid* → char* for %s
connection.c: %x → %lx for long flags
cmd_funcs.c: %d → %zu for size_t; cast gpointer to char* for %s
cmd_defs.c: %d → %u for g_list_length() return (guint)
iq.c: barejid → fulljid for from_jid
console.c, mucwin.c, privwin.c, account.c, omemo.c, presence.c:
gpointer → (char*) casts for %s
Const-correctness and cleanup:

database.c: const for type, query, sort variables
form.c/xmpp.h: const for form_set_value parameter
files.c: refactor to early return, eliminating NULL logfile path
muc.c/muc.h: remove meaningless top-level const on return type
common.c: const for URL string literal
Remove stale declarations: cons_show_desktop_prefs (ui.h),
connection_set_priority (connection.h),
omemo_devicelist_configure_and_request (omemo.h)
test_common.c: add currb NULL check to silence -Wnull-dereference
Tooling (check-cwe134.sh):

Reduce from 5 checks to 2 (checks 1-3 redundant with -Wformat=2)
Check 1: verify known wrappers have G_GNUC_PRINTF attribute
Check 2: auto-detect unannotated variadic printf-like functions
Match both const char* and const gchar* in variadic patterns

Author: jabber.developer2 <jabber.developer2@jabber.space>

src/xmpp/connection.c

@@ -239,7 +239,7 @@ _conn_apply_settings(const char* const jid, const char* const passwd, const char
     }
 
     if (xmpp_conn_set_flags(conn.xmpp_conn, flags)) {
-        log_error("libstrophe doesn't accept this combination of flags: 0x%x", flags);
+        log_error("libstrophe doesn't accept this combination of flags: 0x%lx", flags);
         conn.conn_status = JABBER_DISCONNECTED;
         return FALSE;
     }

src/xmpp/connection.h

@@ -51,7 +51,6 @@ jabber_conn_status_t connection_register(const char* const altdomain, int port,
 void connection_set_disconnected(void);
 
 void connection_set_priority(const int priority);
-void connection_set_priority(int priority);
 void connection_set_disco_items(GSList* items);
 
 xmpp_conn_t* connection_get_conn(void);

src/xmpp/form.c

@@ -458,7 +458,7 @@ form_get_field_type(DataForm* form, const char* const tag)
 }
 
 void
-form_set_value(DataForm* form, const char* const tag, char* value)
+form_set_value(DataForm* form, const char* const tag, const char* value)
 {
     char* var = g_hash_table_lookup(form->tag_to_var, tag);
     if (var) {

src/xmpp/iq.c

@@ -921,7 +921,7 @@ _caps_response_id_handler(xmpp_stanza_t* const stanza, void* const userdata)
     // handle error responses
     if (g_strcmp0(type, STANZA_TYPE_ERROR) == 0) {
         auto_char char* error_message = stanza_get_error_message(stanza);
-        log_warning("Error received for capabilities response from %s: ", from, error_message);
+        log_warning("Error received for capabilities response from %s: %s", from, error_message);
         return 0;
     }
 
@@ -996,7 +996,7 @@ _caps_response_for_jid_id_handler(xmpp_stanza_t* const stanza, void* const userd
     // handle error responses
     if (g_strcmp0(type, STANZA_TYPE_ERROR) == 0) {
         auto_char char* error_message = stanza_get_error_message(stanza);
-        log_warning("Error received for capabilities response from %s: ", from, error_message);
+        log_warning("Error received for capabilities response from %s: %s", from, error_message);
         return 0;
     }
 
@@ -1054,7 +1054,7 @@ _caps_response_legacy_id_handler(xmpp_stanza_t* const stanza, void* const userda
     // handle error responses
     if (g_strcmp0(type, STANZA_TYPE_ERROR) == 0) {
         auto_char char* error_message = stanza_get_error_message(stanza);
-        log_warning("Error received for capabilities response from %s: ", from, error_message);
+        log_warning("Error received for capabilities response from %s: %s", from, error_message);
         return 0;
     }
 
@@ -1254,7 +1254,7 @@ _command_exec_response_handler(xmpp_stanza_t* const stanza, void* const userdata
     if (g_strcmp0(type, STANZA_TYPE_ERROR) == 0) {
         auto_char char* error_message = stanza_get_error_message(stanza);
         log_debug("Error executing command %s for %s: %s", command, from, error_message);
-        win_command_exec_error(win, command, error_message);
+        win_command_exec_error(win, command, "%s", error_message);
         return 0;
     }
 

src/xmpp/muc.c

@@ -427,7 +427,7 @@ muc_rooms(void)
  * Return current users nickname for the specified room
  * The nickname is owned by the chat room and should not be modified or freed
  */
-const char* const
+const char*
 muc_nick(const char* const room)
 {
     ChatRoom* chat_room = g_hash_table_lookup(rooms, room);

src/xmpp/muc.h

@@ -93,7 +93,7 @@ GList* muc_rooms(void);
 
 void muc_set_features(const char* const room, GSList* features);
 
-const char* const muc_nick(const char* const room);
+const char* muc_nick(const char* const room);
 char* muc_password(const char* const room);
 
 void muc_nick_change_start(const char* const room, const char* const new_nick);

src/xmpp/omemo.c

@@ -353,6 +353,7 @@ omemo_receive_message(xmpp_stanza_t* const stanza, gboolean* trusted)
 {
     char* plaintext = NULL;
     const char* type = xmpp_stanza_get_type(stanza);
+    const char* from = xmpp_stanza_get_from(stanza);
     GList* keys = NULL;
     unsigned char* iv_raw = NULL;
     unsigned char* payload_raw = NULL;
@@ -434,8 +435,6 @@ omemo_receive_message(xmpp_stanza_t* const stanza, gboolean* trusted)
         keys = g_list_append(keys, key);
     }
 
-    const char* from = xmpp_stanza_get_from(stanza);
-
     plaintext = omemo_on_message_recv(from, sid, iv_raw, iv_len,
                                       keys, payload_raw, payload_len,
                                       g_strcmp0(type, STANZA_TYPE_GROUPCHAT) == 0, trusted);
@@ -471,7 +470,8 @@ _omemo_receive_devicelist(xmpp_stanza_t* const stanza, void* const userdata)
 
         const char* code = xmpp_stanza_get_attribute(error, "code");
         if (g_strcmp0(code, "404") == 0) {
-            goto out;
+            omemo_set_device_list(from, NULL);
+            return 1;
         }
     }
 
@@ -517,7 +517,8 @@ _omemo_receive_devicelist(xmpp_stanza_t* const stanza, void* const userdata)
         log_warning("[OMEMO] User %s has a non 'current' device item list: %s.", from, xmpp_stanza_get_id(first));
         item = first;
     } else {
-        goto out;
+        omemo_set_device_list(from, device_list);
+        return 1;
     }
 
     xmpp_stanza_t* list = xmpp_stanza_get_child_by_ns(item, STANZA_NS_OMEMO);
@@ -539,7 +540,6 @@ _omemo_receive_devicelist(xmpp_stanza_t* const stanza, void* const userdata)
         }
     }
 
-out:
     omemo_set_device_list(from, device_list);
 
     return 1;

src/xmpp/omemo.h

@@ -38,7 +38,6 @@
 #include "xmpp/iq.h"
 
 void omemo_devicelist_subscribe(void);
-void omemo_devicelist_configure_and_request(void);
 void omemo_devicelist_publish(GList* device_list);
 void omemo_devicelist_request(const char* const jid);
 void omemo_bundle_publish(gboolean first);

src/xmpp/presence.c

@@ -501,7 +501,7 @@ _subscribe_handler(xmpp_stanza_t* const stanza)
 {
     const char* from = xmpp_stanza_get_from(stanza);
     if (!from) {
-        log_warning("Subscribe presence handler received with no from attribute", from);
+        log_warning("Subscribe presence handler received with no from attribute");
     }
     log_debug("Subscribe presence handler fired for %s", from);
 

src/xmpp/stanza.c

@@ -1948,7 +1948,7 @@ stanza_attach_priority(xmpp_ctx_t* const ctx, xmpp_stanza_t* const presence, con
         return;
     }
 
-    char pri_str[10];
+    char pri_str[12];
     snprintf(pri_str, sizeof(pri_str), "%d", pri);
 
     xmpp_stanza_t* priority = xmpp_stanza_new(ctx);
@@ -2007,7 +2007,7 @@ stanza_attach_last_activity(xmpp_ctx_t* const ctx,
     xmpp_stanza_t* query = xmpp_stanza_new(ctx);
     xmpp_stanza_set_name(query, STANZA_NAME_QUERY);
     xmpp_stanza_set_ns(query, STANZA_NS_LASTACTIVITY);
-    char idle_str[10];
+    char idle_str[12];
     snprintf(idle_str, sizeof(idle_str), "%d", idle);
     xmpp_stanza_set_attribute(query, STANZA_ATTR_SECONDS, idle_str);
     xmpp_stanza_add_child(presence, query);

src/xmpp/vcard.c

@@ -1300,7 +1300,7 @@ _vcard_photo_result(xmpp_stanza_t* const stanza, void* userdata)
         return 1;
     }
 
-    GString* filename;
+    GString* filename = NULL;
 
     if (!data->filename) {
         auto_gchar gchar* path = files_get_data_path(DIR_PHOTOS);
@@ -1340,6 +1340,11 @@ _vcard_photo_result(xmpp_stanza_t* const stanza, void* userdata)
 
     GError* err = NULL;
 
+    if (!filename) {
+        cons_show_error("Unable to determine filename for photo");
+        return 1;
+    }
+
     if (g_file_set_contents(filename->str, (gchar*)photo->data, photo->length, &err) == FALSE) {
         cons_show_error("Unable to save photo: %s", err->message);
         g_error_free(err);

src/xmpp/xmpp.h

@@ -305,7 +305,7 @@ char* blocked_ac_find(const char* const search_str, gboolean previous, void* con
 void blocked_ac_reset(void);
 
 void form_destroy(DataForm* form);
-void form_set_value(DataForm* form, const char* const tag, char* value);
+void form_set_value(DataForm* form, const char* const tag, const char* value);
 gboolean form_add_unique_value(DataForm* form, const char* const tag, char* value);
 void form_add_value(DataForm* form, const char* const tag, char* value);
 gboolean form_remove_value(DataForm* form, const char* const tag, char* value);