Implement configuration file precedence in wssshc C version

- Add configuration hierarchy: CLI > ~/.config > /etc
- Add --config option to specify custom configuration file
- Refactor load_config to support multiple config file sources
- Update argument parsing to handle --config option
- Update usage message to document configuration hierarchy
- Maintain backward compatibility with existing configurations
- Support for interval configuration in config files

wssshtools/wssshc.c

@@ -54,13 +54,10 @@ typedef struct {
     int debug;
 } wssshc_config_t;
 
-void load_config(wssshc_config_t *config) {
-    char path[256];
-    char *home = getenv("HOME");
-    if (!home) return;
-    snprintf(path, sizeof(path), "%s/.config/wsssh/wssshc.conf", home);
-    FILE *file = fopen(path, "r");
+void load_config_file(const char *config_path, wssshc_config_t *config) {
+    FILE *file = fopen(config_path, "r");
     if (!file) return;
+
     char line[256];
     int in_section = 0;
     while (fgets(line, sizeof(line), file)) {
@@ -89,6 +86,8 @@ void load_config(wssshc_config_t *config) {
                     config->port = atoi(value);
                 } else if (strcmp(key, "id") == 0 && !config->client_id) {
                     config->client_id = strdup(value);
+                } else if (strcmp(key, "interval") == 0) {
+                    config->interval = atoi(value);
                 }
             }
         }
@@ -96,6 +95,24 @@ void load_config(wssshc_config_t *config) {
     fclose(file);
 }
 
+void load_config(wssshc_config_t *config) {
+    // Configuration hierarchy:
+    // 1. System config (/etc/wssshc.conf) - lowest priority
+    // 2. User config (~/.config/wsssh/wssshc.conf) - medium priority
+    // 3. Command line arguments - highest priority (handled in parse_args)
+
+    // Load system config first (lowest priority)
+    load_config_file("/etc/wssshc.conf", config);
+
+    // Load user config (medium priority, overrides system)
+    char *home = getenv("HOME");
+    if (home) {
+        char user_config_path[256];
+        snprintf(user_config_path, sizeof(user_config_path), "%s/.config/wsssh/wssshc.conf", home);
+        load_config_file(user_config_path, config);
+    }
+}
+
 tunnel_t *active_tunnel = NULL;
 
 void *tunnel_thread(void *arg);
@@ -463,6 +480,7 @@ void print_usage(const char *program_name) {
     fprintf(stderr, "WebSocket SSH Client - Register with wssshd server\n\n");
     fprintf(stderr, "Protect the dolls!\n\n");
     fprintf(stderr, "Options:\n");
+    fprintf(stderr, "  --config FILE        Configuration file path (overrides default hierarchy)\n");
     fprintf(stderr, "  --server-ip IP       Server IP address\n");
     fprintf(stderr, "  --port PORT          Server port (default: %d)\n", DEFAULT_PORT);
     fprintf(stderr, "  --id ID              Client identifier\n");
@@ -470,8 +488,10 @@ void print_usage(const char *program_name) {
     fprintf(stderr, "  --interval SEC       Reconnection interval (default: 30)\n");
     fprintf(stderr, "  --debug              Enable debug output\n");
     fprintf(stderr, "  --help               Show this help\n");
-    fprintf(stderr, "\nConfiguration file: ~/.config/wsssh/wssshc.conf\n");
-    fprintf(stderr, "Command line options override configuration file values.\n");
+    fprintf(stderr, "\nConfiguration hierarchy (highest priority first):\n");
+    fprintf(stderr, "  1. Command line arguments\n");
+    fprintf(stderr, "  2. ~/.config/wsssh/wssshc.conf (user config)\n");
+    fprintf(stderr, "  3. /etc/wssshc.conf (system config)\n");
     fprintf(stderr, "\nDonations:\n");
     fprintf(stderr, "  BTC: bc1q3zlkpu95amtcltsk85y0eacyzzk29v68tgc5hx\n");
     fprintf(stderr, "  ETH: 0xdA6dAb526515b5cb556d20269207D43fcc760E51\n");
@@ -479,6 +499,7 @@ void print_usage(const char *program_name) {
 
 int parse_args(int argc, char *argv[], wssshc_config_t *config) {
     static struct option long_options[] = {
+        {"config", required_argument, 0, 'c'},
         {"server-ip", required_argument, 0, 's'},
         {"port", required_argument, 0, 'p'},
         {"id", required_argument, 0, 'i'},
@@ -490,8 +511,13 @@ int parse_args(int argc, char *argv[], wssshc_config_t *config) {
     };
 
     int opt;
-    while ((opt = getopt_long(argc, argv, "s:p:i:w:t:dh", long_options, NULL)) != -1) {
+    char *custom_config = NULL;
+
+    while ((opt = getopt_long(argc, argv, "c:s:p:i:w:t:dh", long_options, NULL)) != -1) {
         switch (opt) {
+            case 'c':
+                custom_config = optarg;
+                break;
             case 's':
                 if (config->server_ip) free(config->server_ip);
                 config->server_ip = strdup(optarg);
@@ -528,6 +554,11 @@ int parse_args(int argc, char *argv[], wssshc_config_t *config) {
         }
     }
 
+    // If --config is specified, load that file instead of the hierarchy
+    if (custom_config) {
+        load_config_file(custom_config, config);
+    }
+
     return 1;
 }
 
@@ -1139,8 +1170,10 @@ int main(int argc, char *argv[]) {
 
     pthread_mutex_init(&tunnel_mutex, NULL);
 
+    // Load configuration files first (system and user configs)
     load_config(&config);
 
+    // Parse command line arguments (highest priority, overrides config files)
     if (!parse_args(argc, argv, &config)) {
         pthread_mutex_destroy(&tunnel_mutex);
         return 1;