vrl/stdlib/
ip_subnet.rs

1use crate::compiler::prelude::*;
2use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
3
4fn ip_subnet(value: &Value, mask: &Value) -> Resolved {
5    let value: IpAddr = value
6        .try_bytes_utf8_lossy()?
7        .parse()
8        .map_err(|err| format!("unable to parse IP address: {err}"))?;
9    let mask = mask.try_bytes_utf8_lossy()?;
10    let mask = if mask.starts_with('/') {
11        // The parameter is a subnet.
12        let subnet = parse_subnet(&mask)?;
13        match value {
14            IpAddr::V4(_) => {
15                if subnet > 32 {
16                    return Err("subnet cannot be greater than 32 for ipv4 addresses".into());
17                }
18
19                ipv4_mask(subnet)
20            }
21            IpAddr::V6(_) => {
22                if subnet > 128 {
23                    return Err("subnet cannot be greater than 128 for ipv6 addresses".into());
24                }
25
26                ipv6_mask(subnet)
27            }
28        }
29    } else {
30        // The parameter is a mask.
31        mask.parse()
32            .map_err(|err| format!("unable to parse mask: {err}"))?
33    };
34    Ok(mask_ips(value, mask)?.to_string().into())
35}
36
37#[derive(Clone, Copy, Debug)]
38pub struct IpSubnet;
39
40impl Function for IpSubnet {
41    fn identifier(&self) -> &'static str {
42        "ip_subnet"
43    }
44
45    fn usage(&self) -> &'static str {
46        indoc! {"
47            Extracts the subnet address from the `ip` using the supplied `subnet`.
48        "}
49    }
50
51    fn category(&self) -> &'static str {
52        Category::Ip.as_ref()
53    }
54
55    fn internal_failure_reasons(&self) -> &'static [&'static str] {
56        &[
57            "`ip` is not a valid IP address.",
58            "`subnet` is not a valid subnet.",
59        ]
60    }
61
62    fn return_kind(&self) -> u16 {
63        kind::BYTES
64    }
65
66    fn notices(&self) -> &'static [&'static str] {
67        &[indoc! {"
68            Works with both IPv4 and IPv6 addresses. The IP version for the mask must be the same as
69            the supplied address.
70        "}]
71    }
72
73    fn parameters(&self) -> &'static [Parameter] {
74        const PARAMETERS: &[Parameter] = &[
75            Parameter::required("value", kind::BYTES, "The IP address (v4 or v6)."),
76            Parameter::required("subnet", kind::BYTES, "The subnet to extract from the IP address. This can be either a prefix length like `/8` or a net mask
77like `255.255.0.0`. The net mask can be either an IPv4 or IPv6 address."),
78        ];
79        PARAMETERS
80    }
81
82    fn examples(&self) -> &'static [Example] {
83        &[
84            example! {
85                title: "IPv4 subnet",
86                source: r#"ip_subnet!("192.168.10.32", "255.255.255.0")"#,
87                result: Ok("192.168.10.0"),
88            },
89            example! {
90                title: "IPv6 subnet",
91                source: r#"ip_subnet!("2404:6800:4003:c02::64", "/32")"#,
92                result: Ok("2404:6800::"),
93            },
94            example! {
95                title: "Subnet /1",
96                source: r#"ip_subnet!("192.168.0.1", "/1")"#,
97                result: Ok("128.0.0.0"),
98            },
99        ]
100    }
101
102    fn compile(
103        &self,
104        _state: &state::TypeState,
105        _ctx: &mut FunctionCompileContext,
106        arguments: ArgumentList,
107    ) -> Compiled {
108        let value = arguments.required("value");
109        let subnet = arguments.required("subnet");
110
111        Ok(IpSubnetFn { value, subnet }.as_expr())
112    }
113}
114
115#[derive(Debug, Clone)]
116struct IpSubnetFn {
117    value: Box<dyn Expression>,
118    subnet: Box<dyn Expression>,
119}
120
121impl FunctionExpression for IpSubnetFn {
122    fn resolve(&self, ctx: &mut Context) -> Resolved {
123        let value = self.value.resolve(ctx)?;
124        let mask = self.subnet.resolve(ctx)?;
125
126        ip_subnet(&value, &mask)
127    }
128
129    fn type_def(&self, _: &state::TypeState) -> TypeDef {
130        TypeDef::bytes().fallible()
131    }
132}
133
134/// Parses a subnet in the form "/8" returns the number.
135fn parse_subnet(subnet: &str) -> ExpressionResult<u32> {
136    let subnet = subnet[1..]
137        .parse()
138        .map_err(|_| format!("{subnet} is not a valid subnet"))?;
139    Ok(subnet)
140}
141
142/// Masks the address by performing a bitwise AND between the two addresses.
143fn mask_ips(ip: IpAddr, mask: IpAddr) -> ExpressionResult<IpAddr> {
144    match (ip, mask) {
145        (IpAddr::V4(addr), IpAddr::V4(mask)) => {
146            let addr: u32 = addr.into();
147            let mask: u32 = mask.into();
148            Ok(Ipv4Addr::from(addr & mask).into())
149        }
150        (IpAddr::V6(addr), IpAddr::V6(mask)) => {
151            let mut masked = [0; 8];
152            for ((masked, addr), mask) in masked
153                .iter_mut()
154                .zip(addr.segments().iter())
155                .zip(mask.segments().iter())
156            {
157                *masked = addr & mask;
158            }
159
160            Ok(IpAddr::from(masked))
161        }
162        (IpAddr::V6(_), IpAddr::V4(_)) => {
163            Err("attempting to mask an ipv6 address with an ipv4 mask".into())
164        }
165        (IpAddr::V4(_), IpAddr::V6(_)) => {
166            Err("attempting to mask an ipv4 address with an ipv6 mask".into())
167        }
168    }
169}
170
171/// Returns an ipv4 address that masks out the given number of bits.
172fn ipv4_mask(subnet_bits: u32) -> IpAddr {
173    let bits = !0u32 << (32 - subnet_bits);
174    Ipv4Addr::from(bits).into()
175}
176
177/// Returns an ipv6 address that masks out the given number of bits.
178fn ipv6_mask(subnet_bits: u32) -> IpAddr {
179    let bits = !0u128 << (128 - subnet_bits);
180    Ipv6Addr::from(bits).into()
181}
182
183#[cfg(test)]
184mod tests {
185    use super::*;
186    use crate::value;
187
188    test_function![
189        ip_subnet => IpSubnet;
190
191        ipv4 {
192            args: func_args![value: "192.168.10.23",
193                             subnet: "255.255.0.0"],
194            want: Ok(value!("192.168.0.0")),
195            tdef: TypeDef::bytes().fallible(),
196        }
197
198        ipv6 {
199            args: func_args![value: "2404:6800:4003:c02::64",
200                             subnet: "ff00::"],
201            want: Ok(value!("2400::")),
202            tdef: TypeDef::bytes().fallible(),
203        }
204
205        ipv4_subnet {
206            args: func_args![value: "192.168.10.23",
207                             subnet: "/16"],
208            want: Ok(value!("192.168.0.0")),
209            tdef: TypeDef::bytes().fallible(),
210        }
211
212        ipv4_smaller_subnet {
213            args: func_args![value: "192.168.10.23",
214                             subnet: "/12"],
215            want: Ok(value!("192.160.0.0")),
216            tdef: TypeDef::bytes().fallible(),
217        }
218
219        ipv6_subnet {
220            args: func_args![value: "2404:6800:4003:c02::64",
221                             subnet: "/32"],
222            want: Ok(value!("2404:6800::")),
223            tdef: TypeDef::bytes().fallible(),
224        }
225    ];
226}
vrl/stdlib/ip_subnet.rs

vrl/stdlib/
ip_subnet.rs
