ruma_identifiers_validation/
server_name.rs

1use crate::error::Error;
2
3pub fn validate(server_name: &str) -> Result<(), Error> {
4    use std::net::Ipv6Addr;
5
6    if server_name.is_empty() {
7        return Err(Error::InvalidServerName);
8    }
9
10    // As per spec, the server name can be a hostname plus an optional port.
11    //
12    // The hostname is defined as follows:
13    //
14    // hostname    = IPv4address / "[" IPv6address "]" / dns-name
15    //
16    // 1. IPv4 addresses are at most 15 characters long.
17    // 2. IPv6 addresses are at most 45 characters long.
18    // 3. DNS names are at most 255 characters long.
19    //
20    // The optional port must be separated by a ":" character followed by at most 5 digits.
21    //
22    // This brings the maximum allowed length of a server name to 255 + 1 + 5 => 261.
23    //
24    // [1]: https://spec.matrix.org/v1.19/appendices/#server-name
25    if server_name.len() > 261 {
26        return Err(Error::InvalidServerName);
27    }
28
29    let end_of_host = if server_name.starts_with('[') {
30        let Some(end_of_ipv6) = server_name.find(']') else {
31            return Err(Error::InvalidServerName);
32        };
33
34        if server_name[1..end_of_ipv6].parse::<Ipv6Addr>().is_err() {
35            return Err(Error::InvalidServerName);
36        }
37
38        end_of_ipv6 + 1
39    } else {
40        #[allow(clippy::unnecessary_lazy_evaluations)]
41        let end_of_host = server_name.find(':').unwrap_or_else(|| server_name.len());
42
43        if end_of_host == 0 {
44            return Err(Error::InvalidServerName);
45        }
46
47        if server_name[..end_of_host]
48            .bytes()
49            .any(|byte| !(byte.is_ascii_alphanumeric() || byte == b'-' || byte == b'.'))
50        {
51            return Err(Error::InvalidServerName);
52        }
53
54        end_of_host
55    };
56
57    if server_name.len() != end_of_host
58        && (
59            // hostname is followed by something other than ":port"
60            server_name.as_bytes()[end_of_host] != b':'
61            // the remaining characters after ':' are not a valid port
62            || server_name[end_of_host + 1..].parse::<u16>().is_err()
63        )
64    {
65        Err(Error::InvalidServerName)
66    } else {
67        Ok(())
68    }
69}
70
71#[cfg(test)]
72mod tests {
73    use super::validate;
74    use crate::user_id;
75
76    #[test]
77    fn rejects_hostless_server_name_with_port() {
78        assert!(validate(":8448").is_err());
79    }
80
81    #[test]
82    fn rejects_user_id_with_hostless_server_name() {
83        assert!(user_id::validate("@alice::8448").is_err());
84    }
85}
ruma_identifiers_validation/server_name.rs

ruma_identifiers_validation/
server_name.rs
