Add system-wide config support for wsssht with proper precedence

- Update read_config_value_from_file() to support config precedence:
  1. ~/.config/wsssh/wssht.conf (user config)
  2. /etc/wsssht.conf (system config)
- Update man page to document config file precedence order
- Command line options still have highest priority

wssshtools/man/wsssht.1

@@ -108,9 +108,20 @@ Press Ctrl+C to close the tunnel and exit.
 .RE
 .SH CONFIGURATION
 .B wsssht
-supports a configuration file at
+supports configuration files with the following precedence order:
+.RS
+.IP 1. 3
+Command line options (highest priority)
+.IP 2. 3
+User configuration:
 .I ~/.config/wsssh/wssht.conf
-with the following options:
+.IP 3. 3
+System configuration:
+.I /etc/wsssht.conf
+(lowest priority)
+.RE
+.PP
+Configuration options:
 .PP
 .RS
 .nf
@@ -130,10 +141,15 @@ Note: Unlike
 and
 .BR wsscp (1),
 .B wsssht
-uses its own configuration file
+uses its own configuration files
 .I wssht.conf
 instead of sharing
 .I wsssh.conf.
+System administrators can provide default settings in
+.I /etc/wsssht.conf
+which will be overridden by user settings in
+.I ~/.config/wsssh/wssht.conf
+and command line options.
 .SH SEE ALSO
 .BR wsssh (1),
 .BR wsscp (1),

wssshtools/wssshlib.c

@@ -92,12 +92,15 @@ char *read_config_value(const char *key) {
 }
 
 char *read_config_value_from_file(const char *key, const char *config_file) {
+    char *result = NULL;
+
+    // First try user config: ~/.config/wsssh/{config_file}.conf
     char *home = getenv("HOME");
-    if (!home) return NULL;
-    char path[PATH_MAX];
-    snprintf(path, sizeof(path), "%s/.config/wsssh/%s.conf", home, config_file);
-    FILE *f = fopen(path, "r");
-    if (!f) return NULL;
+    if (home) {
+        char user_path[PATH_MAX];
+        snprintf(user_path, sizeof(user_path), "%s/.config/wsssh/%s.conf", home, config_file);
+        FILE *f = fopen(user_path, "r");
+        if (f) {
             char line[256];
             char section[64] = "";
             while (fgets(line, sizeof(line), f)) {
@@ -124,15 +127,61 @@ char *read_config_value_from_file(const char *key, const char *config_file) {
                     end = value + strlen(value) - 1;
                     while (end > value && (*end == ' ' || *end == '\t' || *end == '\n')) *end-- = '\0';
 
-            // Check if key matches (case-insensitive for section names)
+                    // Check if key matches
                     if (strcmp(config_key, key) == 0) {
+                        result = strdup(value);
+                        break;
+                    }
+                }
+            }
             fclose(f);
-                return strdup(value);
+        }
+    }
+
+    // If not found in user config, try system config: /etc/{config_file}.conf
+    if (!result) {
+        char system_path[PATH_MAX];
+        snprintf(system_path, sizeof(system_path), "/etc/%s.conf", config_file);
+        FILE *f = fopen(system_path, "r");
+        if (f) {
+            char line[256];
+            char section[64] = "";
+            while (fgets(line, sizeof(line), f)) {
+                // Check for section headers
+                if (line[0] == '[') {
+                    sscanf(line, "[%63[^]]", section);
+                    continue;
+                }
+                // Skip comments and empty lines
+                if (line[0] == '#' || line[0] == ';' || line[0] == '\n') continue;
+
+                char *equals = strchr(line, '=');
+                if (equals) {
+                    *equals = '\0';
+                    char *config_key = line;
+                    char *value = equals + 1;
+
+                    // Trim whitespace
+                    while (*config_key == ' ' || *config_key == '\t') config_key++;
+                    char *end = config_key + strlen(config_key) - 1;
+                    while (end > config_key && (*end == ' ' || *end == '\t')) *end-- = '\0';
+
+                    while (*value == ' ' || *value == '\t') value++;
+                    end = value + strlen(value) - 1;
+                    while (end > value && (*end == ' ' || *end == '\t' || *end == '\n')) *end-- = '\0';
+
+                    // Check if key matches
+                    if (strcmp(config_key, key) == 0) {
+                        result = strdup(value);
+                        break;
                     }
                 }
             }
             fclose(f);
-    return NULL;
+        }
+    }
+
+    return result;
 }
 
 void print_trans_flag(void) {