v0.1.0

src/passwords.rs

@@ -99,6 +99,34 @@ pub fn validate_new_password(config: &AppConfig, password: &str) -> AppResult<()
     Ok(())
 }
 
+/// Generate a random password that satisfies the configured policy
+/// (PostfixAdmin `generate_password()`).
+pub fn generate_password(config: &AppConfig) -> String {
+    const LETTERS: &[u8] = b"abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ";
+    const DIGITS: &[u8] = b"23456789";
+    let length = config
+        .password
+        .min_length
+        .max(config.password.min_letters + config.password.min_digits)
+        .max(12);
+    let mut rng = rand::rng();
+    let mut pick = |set: &[u8]| set[(rng.next_u32() as usize) % set.len()] as char;
+    let mut chars: Vec<char> = Vec::with_capacity(length);
+    for _ in 0..config.password.min_digits.max(2) {
+        chars.push(pick(DIGITS));
+    }
+    while chars.len() < length {
+        chars.push(pick(LETTERS));
+    }
+    // Fisher-Yates shuffle so the digits are not always in front.
+    let mut rng = rand::rng();
+    for i in (1..chars.len()).rev() {
+        let j = (rng.next_u32() as usize) % (i + 1);
+        chars.swap(i, j);
+    }
+    chars.into_iter().collect()
+}
+
 /// Verify an existing PostfixAdmin hash. The format stored in the database wins
 /// over the currently configured format whenever it identifies itself.
 pub async fn verify(config: &AppConfig, password: &str, stored: &str, username: &str) -> bool {