Initial commit.

9 files changed, 1380 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f0e3bca
--- /dev/null
+++ b/.gitignore
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+/target
+**/*.rs.bk
\ No newline at end of file
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diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..177c77f
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "wgconfd"
+version = "0.1.0"
+authors = ["Hristo Venev <hristo@venev.name>"]
+edition = "2018"
+
+[dependencies]
+arrayref = "*"
+serde = "*"
+serde_derive = "*"
+serde_json = "*"
+chrono = "*"
+curl = "*"
+
+[profile.release]
+panic = "abort"
diff --git a/src/bin.rs b/src/bin.rs
new file mode 100644
index 0000000..2df3856
--- /dev/null
+++ b/src/bin.rs
@@ -0,0 +1,56 @@
+#[inline]
+pub fn i64_to_be(v: i64) -> [u8; 8] {
+    u64_to_be(v as u64)
+}
+
+pub fn i64_from_be(v: [u8; 8]) -> i64 {
+    u64_from_be(v) as i64
+}
+
+pub fn u64_to_be(v: u64) -> [u8; 8] {
+    [
+        (v >> 56) as u8,
+        (v >> 48) as u8,
+        (v >> 40) as u8,
+        (v >> 32) as u8,
+        (v >> 24) as u8,
+        (v >> 16) as u8,
+        (v >> 8) as u8,
+        v as u8,
+    ]
+}
+
+pub fn u64_from_be(v: [u8; 8]) -> u64 {
+    (u64::from(v[0]) << 56) |
+    (u64::from(v[1]) << 48) |
+    (u64::from(v[2]) << 40) |
+    (u64::from(v[3]) << 32) |
+    (u64::from(v[4]) << 24) |
+    (u64::from(v[5]) << 16) |
+    (u64::from(v[6]) << 8) |
+    u64::from(v[7])
+}
+
+pub fn u32_to_be(v: u32) -> [u8; 4] {
+    [
+        (v >> 24) as u8,
+        (v >> 16) as u8,
+        (v >> 8) as u8,
+        v as u8,
+    ]
+}
+
+pub fn u32_from_be(v: [u8; 4]) -> u32 {
+    (u32::from(v[0]) << 24) |
+    (u32::from(v[1]) << 16) |
+    (u32::from(v[2]) << 8) |
+    u32::from(v[3])
+}
+
+pub fn u16_to_be(v: u16) -> [u8; 2] {
+    [(v >> 8) as u8, v as u8]
+}
+
+pub fn u16_from_be(v: [u8; 2]) -> u16 {
+    (u16::from(v[0]) << 8) | u16::from(v[1])
+}
diff --git a/src/config.rs b/src/config.rs
new file mode 100644
index 0000000..6411b3a
--- /dev/null
+++ b/src/config.rs
@@ -0,0 +1,67 @@
+use ::std::collections::HashSet;
+use ::serde_derive;
+use crate::ip::{Ipv4Set, Ipv6Set};
+
+#[serde(deny_unknown_fields)]
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Source {
+    pub url: String,
+    pub psk: Option<String>,
+    pub ipv4: Ipv4Set,
+    pub ipv6: Ipv6Set,
+}
+
+#[serde(deny_unknown_fields)]
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct PeerConfig {
+    #[serde(default = "default_min_keepalive")]
+    pub min_keepalive: u32,
+    #[serde(default = "default_max_keepalive")]
+    pub max_keepalive: u32,
+
+    pub omit_peers: HashSet<String>,
+}
+
+#[serde(deny_unknown_fields)]
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct UpdateConfig {
+    // Number of seconds between regular updates.
+    #[serde(default = "default_refresh")]
+    pub refresh_period: u32,
+}
+
+#[serde(deny_unknown_fields)]
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, Debug)]
+pub struct Config {
+    pub ifname: String,
+    #[serde(default = "default_wg_command")]
+    pub wg_command: String,
+
+    #[serde(flatten)]
+    pub peers: PeerConfig,
+
+    #[serde(flatten)]
+    pub update: UpdateConfig,
+
+    pub sources: Vec<Source>,
+}
+
+fn default_wg_command() -> String {
+    "wg".to_owned()
+}
+
+fn default_min_keepalive() -> u32 {
+    10
+}
+
+fn default_max_keepalive() -> u32 {
+    0
+}
+
+fn default_refresh() -> u32 {
+    1200
+}
diff --git a/src/ip.rs b/src/ip.rs
new file mode 100644
index 0000000..1b21e4c
--- /dev/null
+++ b/src/ip.rs
@@ -0,0 +1,403 @@
+use ::std::{error, fmt, iter, net};
+use ::std::net::{Ipv4Addr, Ipv6Addr};
+use ::std::iter::{IntoIterator, FromIterator};
+use ::std::str::{FromStr};
+use ::serde;
+use crate::bin;
+
+#[derive(Debug)]
+pub struct NetParseError {}
+
+impl error::Error for NetParseError {}
+impl fmt::Display for NetParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Invalid IP network")
+    }
+}
+
+macro_rules! per_proto {
+    ($nett:ident ($addrt:ident; $expecting:expr); $intt:ident($bytes:expr); $sett:ident) => {
+        #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+        pub struct $nett {
+            pub address: $addrt,
+            pub prefix_len: u8,
+        }
+
+        impl $nett {
+            const BITS: u8 = $bytes * 8;
+
+            pub fn contains(&self, other: &$nett) -> bool {
+                if self.prefix_len > other.prefix_len {
+                    return false;
+                }
+                if self.prefix_len == other.prefix_len {
+                    return self.address == other.address;
+                }
+                // self.prefix_len < other.prefix_len = BITS
+                let shift = Self::BITS - self.prefix_len;
+                let v1: $intt = self.address.into();
+                let v2: $intt = other.address.into();
+                v1 >> shift == v2 >> shift
+            }
+        }
+
+        impl fmt::Display for $nett {
+            fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                write!(f, "{}/{}", self.address, self.prefix_len)
+            }
+        }
+        
+        impl FromStr for $nett {
+            type Err = NetParseError;
+            fn from_str(s: &str) -> Result<$nett, NetParseError> {
+                let (addr, pfx) = pfx_split(s)?;
+                let addr = $addrt::from_str(addr).map_err(|_| NetParseError {})?;
+        
+                let r = $nett {
+                    address: addr,
+                    prefix_len: pfx,
+                };
+                if !r.is_valid() {
+                    return Err(NetParseError {});
+                }
+                Ok(r)
+            }
+        }
+
+        impl serde::Serialize for $nett {
+            fn serialize<S: serde::Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> {
+                if ser.is_human_readable() {
+                    ser.serialize_str(&format!("{}", self))
+                } else {
+                    let mut buf = [0u8; $bytes + 1];
+                    *array_mut_ref![&mut buf, 0, $bytes] = self.address.octets();
+                    buf[$bytes] = self.prefix_len;
+                    ser.serialize_bytes(&buf)
+                }
+            }
+        }
+
+        impl<'de> serde::Deserialize<'de> for $nett {
+            fn deserialize<D: serde::Deserializer<'de>>(de: D) -> Result<Self, D::Error> {
+                if de.is_human_readable() {
+                    struct NetVisitor;
+                    impl<'de> serde::de::Visitor<'de> for NetVisitor {
+                        type Value = $nett;
+
+                        fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                            f.write_str($expecting)
+                        }
+
+                        fn visit_str<E: serde::de::Error>(self, s: &str) -> Result<Self::Value, E> {
+                            s.parse().map_err(E::custom)
+                        }
+                    }
+                    de.deserialize_str(NetVisitor)
+                } else {
+                    let buf = <[u8; $bytes+1] as serde::Deserialize>::deserialize(de)?;
+                    let r = $nett {
+                        address: (*array_ref![&buf, 0, $bytes]).into(),
+                        prefix_len: buf[$bytes],
+                    };
+                    if r.is_valid() {
+                        return Err(serde::de::Error::custom(NetParseError {}));
+                    }
+                    Ok(r)
+                }
+            }
+        }
+
+        #[derive(Clone, PartialEq, Eq, PartialOrd, Hash, Debug)]
+        pub struct $sett {
+            nets: Vec<$nett>,
+        }
+
+        impl Default for $sett {
+            #[inline]
+            fn default() -> Self {
+                $sett::new()
+            }
+        }
+
+        impl $sett {
+            #[inline]
+            pub fn new() -> Self {
+                $sett { nets: vec![] }
+            }
+
+            #[inline]
+            fn siblings(a: &$nett, b: &$nett) -> bool {
+                let pfx = a.prefix_len;
+                if b.prefix_len != pfx || pfx == 0 {
+                    return false;
+                }
+                let a: $intt = a.address.into();
+                let b: $intt = b.address.into();
+                a ^ b == 1 << ($nett::BITS - pfx)
+            }
+
+            pub fn insert(&mut self, mut net: $nett) {
+                let mut i = match self.nets.binary_search(&net) {
+                    Err(i) => i,
+                    Ok(_) => {
+                        return;
+                    }
+                };
+                let mut j = i;
+                if i != 0 && self.nets[i-1].contains(&net) {
+                    net = self.nets[i-1];
+                    i -= 1;
+                }
+                while j < self.nets.len() && net.contains(&self.nets[j]) {
+                    j += 1;
+                }
+                loop {
+                    if j < self.nets.len() && Self::siblings(&net, &self.nets[j]) {
+                        j += 1;
+                    } else if i != 0 && Self::siblings(&self.nets[i-1], &net) {
+                        net = self.nets[i-1];
+                        i -= 1;
+                    } else {
+                        break;
+                    }
+                    net.prefix_len -= 1;
+                }
+                self.nets.splice(i..j, iter::once(net));
+            }
+
+            pub fn contains(&self, net: &$nett) -> bool {
+                match self.nets.binary_search(&net) {
+                    Err(i) => {
+                        if i == 0 {
+                            return false;
+                        }
+                        self.nets[i-1].contains(&net)
+                    }
+                    Ok(_) => true,
+                }
+            }
+
+            #[inline]
+            pub fn iter(&self) -> std::slice::Iter<$nett> {
+                self.nets.iter()
+            }
+        }
+
+        impl IntoIterator for $sett {
+            type Item = $nett;
+            type IntoIter = std::vec::IntoIter<$nett>;
+
+            #[inline]
+            fn into_iter(self) -> Self::IntoIter {
+                self.nets.into_iter()
+            }
+        }
+
+        impl FromIterator<$nett> for $sett {
+            fn from_iter<I: IntoIterator<Item=$nett>>(it: I) -> $sett {
+                let mut r = $sett::new();
+                for net in it {
+                    r.insert(net);
+                }
+                r
+            }
+        }
+
+        impl<'a> From<$nett> for $sett {
+            #[inline]
+            fn from(v: $nett) -> $sett {
+                $sett { nets: vec![v] }
+            }
+        }
+
+        impl<'a> From<[$nett; 1]> for $sett {
+            #[inline]
+            fn from(v: [$nett; 1]) -> $sett {
+                $sett { nets: vec![v[0]] }
+            }
+        }
+
+        impl From<$sett> for Vec<$nett> {
+            fn from(v: $sett) -> Vec<$nett> {
+                v.nets
+            }
+        }
+
+        impl From<Vec<$nett>> for $sett {
+            fn from(nets: Vec<$nett>) -> $sett {
+                let mut s = $sett { nets };
+                let len = s.nets.len();
+                if len == 0 {
+                    return s;
+                }
+                s.nets.sort();
+                let mut i = 1;
+                for j in 1..len {
+                    let mut net = s.nets[j];
+                    if i != 0 && s.nets[i-1].contains(&net) {
+                        net = s.nets[i-1];
+                        i -= 1;
+                    }
+                    while i != 0 && Self::siblings(&s.nets[i-1], &net) {
+                        net = s.nets[i-1];
+                        net.prefix_len -= 1;
+                        i -= 1;
+                    }
+                    s.nets[i] = net;
+                    i += 1;
+                }
+                s.nets.splice(i.., iter::empty());
+                s
+            }
+        }
+
+        impl<'a> From<&'a [$nett]> for $sett {
+            #[inline]
+            fn from(nets: &'a [$nett]) -> $sett {
+                Vec::from(nets).into()
+            }
+        }
+
+        impl<'a> From<&'a mut [$nett]> for $sett {
+            #[inline]
+            fn from(nets: &'a mut [$nett]) -> $sett {
+                Vec::from(nets).into()
+            }
+        }
+
+        impl serde::Serialize for $sett {
+            fn serialize<S: serde::Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> {
+                <Vec<$nett> as serde::Serialize>::serialize(&self.nets, ser)
+            }
+        }
+
+        impl<'de> serde::Deserialize<'de> for $sett {
+            fn deserialize<D: serde::Deserializer<'de>>(de: D) -> Result<Self, D::Error> {
+                <Vec<$nett> as serde::Deserialize>::deserialize(de).map($sett::from)
+            }
+        }
+    };
+}
+
+per_proto!(Ipv4Net(Ipv4Addr; "IPv4 network"); u32(4); Ipv4Set);
+per_proto!(Ipv6Net(Ipv6Addr; "IPv6 network"); u128(16); Ipv6Set);
+
+impl Ipv4Net {
+    pub fn is_valid(&self) -> bool {
+        let pfx = self.prefix_len;
+        if pfx > 32 {
+            return false;
+        }
+        if pfx == 32 {
+            return true;
+        }
+        let val: u32 = self.address.into();
+        val & (u32::max_value() >> pfx) == 0
+    }
+}
+
+impl Ipv6Net {
+    pub fn is_valid(&self) -> bool {
+        let pfx = self.prefix_len;
+        if pfx > 128 {
+            return false;
+        }
+        if pfx == 128 {
+            return true;
+        }
+
+        let val: u128 = self.address.into();
+        let val: [u64; 2] = [(val >> 64) as u64, val as u64];
+        if pfx >= 64 {
+            return val[1] & (u64::max_value() >> (pfx - 64)) == 0;
+        }
+        if val[1] != 0 {
+            return false;
+        }
+        val[0] & (u64::max_value() >> pfx) == 0
+    }
+}
+
+fn pfx_split(s: &str) -> Result<(&str, u8), NetParseError> {
+    let i = match s.find("/") {
+        Some(i) => i,
+        None => {
+            return Err(NetParseError {});
+        }
+    };
+    let (addr, pfx) = s.split_at(i);
+    let pfx = u8::from_str(&pfx[1..]).map_err(|_| NetParseError {})?;
+    Ok((addr, pfx))
+}
+
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub struct Endpoint {
+    pub address: Ipv6Addr,
+    pub port: u16,
+}
+
+impl fmt::Display for Endpoint {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.address.segments()[5] == 0xffff {
+            write!(f, "{}:", self.address.to_ipv4().unwrap())?;
+        } else {
+            write!(f, "[{}]:", self.address)?;
+        }
+        write!(f, "{}", self.port)
+    }
+}
+
+impl FromStr for Endpoint {
+    type Err = net::AddrParseError;
+    fn from_str(s: &str) -> Result<Endpoint, net::AddrParseError> {
+        net::SocketAddr::from_str(s)
+            .map(|v| Endpoint {
+                address: match v.ip() {
+                    net::IpAddr::V4(a) => a.to_ipv6_mapped(),
+                    net::IpAddr::V6(a) => a,
+                },
+                port: v.port(),
+            })
+    }
+}
+
+impl serde::Serialize for Endpoint {
+    fn serialize<S: serde::Serializer>(&self, ser: S) -> Result<S::Ok, S::Error> {
+        if ser.is_human_readable() {
+            ser.serialize_str(&format!("{}", self))
+        } else {
+            let mut buf = [0u8; 16 + 2];
+            let (buf_addr, buf_port) = mut_array_refs![&mut buf, 16, 2];
+            *buf_addr = self.address.octets();
+            *buf_port = crate::bin::u16_to_be(self.port);
+            ser.serialize_bytes(&buf)
+        }
+    }
+}
+
+impl<'de> serde::Deserialize<'de> for Endpoint {
+    fn deserialize<D: serde::Deserializer<'de>>(de: D) -> Result<Self, D::Error> {
+        if de.is_human_readable() {
+            struct EndpointVisitor;
+            impl<'de> serde::de::Visitor<'de> for EndpointVisitor {
+                type Value = Endpoint;
+
+                fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                    f.write_str("ip:port")
+                }
+
+                fn visit_str<E: serde::de::Error>(self, s: &str) -> Result<Self::Value, E> {
+                    s.parse().map_err(E::custom)
+                }
+            }
+            de.deserialize_str(EndpointVisitor)
+        } else {
+            let buf = <[u8; 16 + 2] as serde::Deserialize>::deserialize(de)?;
+            let (buf_addr, buf_port) = array_refs![&buf, 16, 2];
+            Ok(Endpoint {
+                address: (*buf_addr).into(),
+                port: bin::u16_from_be(*buf_port),
+            })
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..ad57895
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,203 @@
+#[macro_use]
+extern crate arrayref;
+
+use ::std::io;
+use ::std::time::{Duration, SystemTime, Instant};
+
+mod bin;
+mod ip;
+mod proto;
+mod config;
+mod wg;
+
+struct Source {
+    config: config::Source,
+    data: Option<proto::Source>,
+    next_update: Instant,
+    backoff: Option<u32>,
+}
+
+impl Source {
+    fn new(config: config::Source) -> Source {
+        Source {
+            config,
+            data: None,
+            next_update: Instant::now(),
+            backoff: None,
+        }
+    }
+}
+
+pub struct Device {
+    dev: wg::Device,
+    peer_config: config::PeerConfig,
+    update_config: config::UpdateConfig,
+    sources: Vec<Source>,
+    current: wg::Config,
+}
+
+impl Device {
+    pub fn new(c: config::Config) -> Device {
+        Device {
+            dev: wg::Device::new(c.ifname, c.wg_command),
+            peer_config: c.peers,
+            update_config: c.update,
+            sources: c.sources.into_iter().map(Source::new).collect(),
+            current: wg::Config::new(),
+        }
+    }
+
+    fn make_config(&self, ts: SystemTime) -> (wg::Config, Vec<wg::ConfigError>, SystemTime) {
+        let mut cfg = wg::Config::new();
+        let mut next_update = ts + Duration::from_secs(3600);
+        let mut errs = vec![];
+        for src in self.sources.iter() {
+            if let Some(data) = &src.data {
+                let sc = data.next.as_ref().and_then(|next| {
+                    if ts >= next.update_at {
+                        Some(&next.config)
+                    } else {
+                        next_update = next_update.min(next.update_at);
+                        None
+                    }
+                }).unwrap_or(&data.config);
+                for peer in sc.peers.iter() {
+                    cfg.add_peer(&mut errs, &self.peer_config, &src.config, peer);
+                }
+            }
+        }
+        (cfg, errs, next_update)
+    }
+
+    pub fn update(&mut self) -> io::Result<Instant> {
+        let now = Instant::now();
+        let refresh = self.update_config.refresh_period;
+        let after_refresh = now + Duration::from_secs(u64::from(refresh));
+        let mut next_update = after_refresh;
+        for src in self.sources.iter_mut() {
+            if now < src.next_update {
+                next_update = next_update.min(src.next_update);
+                continue;
+            }
+
+            let r = fetch_source(&src.config.url);
+            let r = match r {
+                Ok(r) => {
+                    eprintln!("<6>Updated [{}]", &src.config.url);
+                    src.data = Some(r);
+                    src.backoff = None;
+                    src.next_update = after_refresh;
+                    continue;
+                }
+                Err(r) => r,
+            };
+
+            eprintln!("<3>Failed to update [{}]: {}", &src.config.url, &r);
+
+            let b = src.backoff.unwrap_or(if src.data.is_some() {
+                refresh / 3
+            } else {
+                u32::min(10, refresh / 10)
+            });
+            let b = (b + b / 3).min(refresh);
+            src.backoff = Some(b);
+            src.next_update = now + Duration::from_secs(u64::from(b));
+            next_update = next_update.min(src.next_update);
+        }
+
+        let sysnow = SystemTime::now();
+        let (config, errors, upd_time) = self.make_config(sysnow);
+        let time_to_upd = upd_time.duration_since(sysnow).unwrap_or(Duration::from_secs(0));
+        next_update = next_update.min(now + time_to_upd);
+
+        if config != self.current {
+            eprintln!("<5>Applying configuration update");
+            for err in errors.iter() {
+                eprintln!("<{}>{}", if err.important { '4' } else { '5' }, err);
+            }
+            self.dev.apply_diff(&self.current, &config)?;
+            self.current = config;
+        }
+        eprintln!("<6>Next configuration update after {:?}", time_to_upd);
+
+        Ok(next_update)
+    }
+}
+
+fn fetch_source(url: &str) -> io::Result<proto::Source> {
+    use ::curl::easy::Easy;
+
+    let mut res = Vec::<u8>::new();
+
+    {
+        let mut req = Easy::new();
+        req.url(url)?;
+
+        {
+            let mut tr = req.transfer();
+            tr.write_function(|data| {
+                res.extend_from_slice(data);
+                Ok(data.len())
+            })?;
+            tr.perform()?;
+        }
+
+        let code = req.response_code()?;
+        if code != 0 && code != 200 {
+            return Err(io::Error::new(io::ErrorKind::Other, format!("HTTP error {}", code)));
+        }
+    }
+
+    let mut de = serde_json::Deserializer::from_slice(&res);
+    let r = serde::Deserialize::deserialize(&mut de)?;
+    Ok(r)
+}
+
+fn load_config(path: &str) -> io::Result<config::Config> {
+    use std::fs;
+    use ::serde_json;
+
+    let config_file = fs::File::open(path)?;
+    let rd = io::BufReader::new(config_file);
+    let mut de = serde_json::Deserializer::from_reader(rd);
+    Ok(serde::Deserialize::deserialize(&mut de)?)
+}
+
+fn main() {
+    use ::std::{env, thread, process};
+
+    let args: Vec<String> = env::args().into_iter().collect();
+    if args.len() != 2 {
+        let arg0 = if args.len() >= 1 {
+            &args[0]
+        } else {
+            "wgconf"
+        };
+        eprintln!("<1>Usage:");
+        eprintln!("<1>    {} CONFIG", arg0);
+        process::exit(1);
+    }
+
+    let config = match load_config(&args[1]) {
+        Ok(c) => c,
+        Err(e) => {
+            eprintln!("<1>Failed to load config: {}", e);
+            process::exit(1);
+        }
+    };
+
+    let mut dev = Device::new(config);
+    loop {
+        let tm = match dev.update() {
+            Ok(t) => t,
+            Err(e) => {
+                eprintln!("<1>{}", e);
+                process::exit(1);
+            }
+        };
+        let now = Instant::now();
+        let sleep = tm.duration_since(now);
+        println!("Sleeping for {:?}", sleep);
+        thread::sleep(sleep);
+    }
+}
diff --git a/src/proto.rs b/src/proto.rs
new file mode 100644
index 0000000..e6759a1
--- /dev/null
+++ b/src/proto.rs
@@ -0,0 +1,77 @@
+use ::std::time::SystemTime;
+use ::serde_derive;
+
+use crate::ip::{Ipv4Net, Ipv6Net, Endpoint};
+
+#[serde(deny_unknown_fields)]
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Peer {
+    pub public_key: String,
+    pub endpoint: Endpoint,
+    #[serde(default = "default_peer_keepalive")]
+    pub keepalive: u32,
+    pub ipv4: Vec<Ipv4Net>,
+    pub ipv6: Vec<Ipv6Net>,
+}
+
+fn default_peer_keepalive() -> u32 {
+    0
+}
+
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct SourceConfig {
+    pub peers: Vec<Peer>,
+}
+
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct SourceNextConfig {
+    #[serde(with = "serde_utc")]
+    pub update_at: SystemTime,
+    #[serde(flatten)]
+    pub config: SourceConfig,
+}
+
+#[derive(serde_derive::Serialize, serde_derive::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Source {
+    #[serde(flatten)]
+    pub config: SourceConfig,
+    pub next: Option<SourceNextConfig>,
+}
+
+mod serde_utc {
+    use ::std::time::SystemTime;
+    use ::chrono::{DateTime, TimeZone, Utc, SecondsFormat};
+    use ::serde::*;
+    use crate::bin;
+
+    pub fn serialize<S: Serializer>(t: &SystemTime, ser: S) -> Result<S::Ok, S::Error> {
+        let t = DateTime::<Utc>::from(*t);
+        if ser.is_human_readable() {
+            ser.serialize_str(&t.to_rfc3339_opts(SecondsFormat::Nanos, true))
+        } else {
+            let mut buf = [0u8; 12];
+            let (buf_secs, buf_nanos) = mut_array_refs![&mut buf, 8, 4];
+            *buf_secs = bin::i64_to_be(t.timestamp());
+            *buf_nanos = bin::u32_to_be(t.timestamp_subsec_nanos());
+            ser.serialize_bytes(&buf)
+        }
+    }
+
+    pub fn deserialize<'de, D: Deserializer<'de>>(de: D) -> Result<SystemTime, D::Error> {
+        if de.is_human_readable() {
+            let s: String = String::deserialize(de)?;
+            let t = DateTime::parse_from_rfc3339(&s).map_err(de::Error::custom)?;
+            Ok(t.into())
+        } else {
+            let mut buf = <[u8; 12]>::deserialize(de)?;
+            let (buf_secs, buf_nanos) = array_refs![&mut buf, 8, 4];
+            let secs = bin::i64_from_be(*buf_secs);
+            let nanos = bin::u32_from_be(*buf_nanos);
+            Ok(Utc.timestamp(secs, nanos).into())
+        }
+    }
+}
diff --git a/src/wg.rs b/src/wg.rs
new file mode 100644
index 0000000..d5a03ff
--- /dev/null
+++ b/src/wg.rs
@@ -0,0 +1,231 @@
+use ::std::{error, io, fmt};
+use ::std::collections::hash_map;
+use hash_map::HashMap;
+use crate::ip::{Ipv4Net, Ipv6Net, Endpoint};
+use crate::{proto, config};
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+struct Peer {
+    endpoint: Endpoint,
+    psk: Option<String>,
+    keepalive: u32,
+    ipv4: Vec<Ipv4Net>,
+    ipv6: Vec<Ipv6Net>,
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Config {
+    peers: HashMap<String, Peer>,
+}
+
+#[derive(Debug)]
+pub struct ConfigError {
+    pub url: String,
+    pub peer: String,
+    pub important: bool,
+    err: &'static str,
+}
+
+impl error::Error for ConfigError {}
+impl fmt::Display for ConfigError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Invalid peer [{}] from [{}]: {}", self.peer, self.url, self.err)
+    }
+}
+        
+impl Config {
+    pub fn new() -> Config {
+        Config {
+            peers: HashMap::new(),
+        }
+    }
+
+    pub fn add_peer(&mut self, errors: &mut Vec<ConfigError>, c: &config::PeerConfig, s: &config::Source, p: &proto::Peer) {
+        if !valid_key(&p.public_key) {
+            errors.push(ConfigError {
+                url: s.url.clone(),
+                peer: p.public_key.clone(),
+                important: true,
+                err: "Invalid public key",
+            });
+            return;
+        }
+
+        if let Some(ref psk) = s.psk {
+            if !valid_key(psk) {
+                errors.push(ConfigError {
+                    url: s.url.clone(),
+                    peer: p.public_key.clone(),
+                    important: true,
+                    err: "Invalid preshared key",
+                });
+                return;
+            }
+        }
+
+        if c.omit_peers.contains(&p.public_key) {
+            return;
+        }
+
+        let ent = match self.peers.entry(p.public_key.clone()) {
+            hash_map::Entry::Occupied(_) => {
+                errors.push(ConfigError {
+                    url: s.url.clone(),
+                    peer: p.public_key.clone(),
+                    important: true,
+                    err: "Duplicate public key",
+                });
+                return;
+            },
+            hash_map::Entry::Vacant(ent) => ent,
+        };
+
+        let mut keepalive = p.keepalive;
+        if c.max_keepalive != 0 && (keepalive == 0 || keepalive > c.max_keepalive) {
+            keepalive = c.max_keepalive;
+        }
+        if keepalive != 0 && keepalive < c.min_keepalive {
+            keepalive = c.min_keepalive;
+        }
+
+        let mut removed = false;
+
+        let mut ipv4 = p.ipv4.clone();
+        ipv4.retain(|i| {
+            let r = s.ipv4.contains(i);
+            if !r { removed = true; }
+            r
+        });
+
+        let mut ipv6 = p.ipv6.clone();
+        ipv6.retain(|i| {
+            let r = s.ipv6.contains(i);
+            if !r { removed = true; }
+            r
+        });
+
+        let r = ent.insert(Peer {
+            endpoint: p.endpoint.clone(),
+            psk: s.psk.clone(),
+            keepalive, ipv4, ipv6,
+        });
+
+        if removed {
+            let all = r.ipv4.is_empty() && r.ipv6.is_empty();
+            errors.push(ConfigError {
+                url: s.url.clone(),
+                peer: p.public_key.clone(),
+                important: all,
+                err: if all { "All IPs removed" } else {"Some IPs removed"},
+            });
+        }
+    }
+}
+
+impl Default for Config {
+    #[inline]
+    fn default() -> Self {
+        Config::new()
+    }
+}
+
+pub struct Device {
+    ifname: String,
+    wg_command: String,
+}
+
+impl Device {
+    pub fn new(ifname: String, wg_command: String) -> Self {
+        Device { ifname, wg_command }
+    }
+
+    pub fn apply_diff(&mut self, old: &Config, new: &Config) -> io::Result<()> {
+        use ::std::process::{Command, Stdio};
+
+        let mut proc = Command::new(&self.wg_command);
+        proc.stdin(Stdio::piped());
+        proc.stdout(Stdio::null());
+        proc.arg("set");
+        proc.arg(&self.ifname);
+
+        let mut psks = Vec::<&str>::new();
+
+        for (pubkey, conf) in new.peers.iter() {
+            if let Some(old_peer) = old.peers.get(pubkey) {
+                if *old_peer == *conf {
+                    continue;
+                }
+            }
+            proc.arg("peer");
+            proc.arg(pubkey);
+            
+            // TODO: maybe skip endpoint?
+            proc.arg("endpoint");
+            proc.arg(format!("{}", conf.endpoint));
+
+            if let Some(psk) = &conf.psk {
+                proc.arg("preshared-key");
+                proc.arg("/dev/stdin");
+                psks.push(psk);
+            }
+
+            let mut ips = String::new();
+            {
+                use std::fmt::Write;
+                for ip in conf.ipv4.iter() {
+                    if !ips.is_empty() { ips.push(','); }
+                    write!(ips, "{}", ip).unwrap();
+                }
+                for ip in conf.ipv6.iter() {
+                    if !ips.is_empty() { ips.push(','); }
+                    write!(ips, "{}", ip).unwrap();
+                }
+            }
+
+            proc.arg("allowed-ips");
+            proc.arg(ips);
+        }
+
+        for pubkey in old.peers.keys() {
+            if new.peers.contains_key(pubkey) {
+                continue;
+            }
+            proc.arg("peer");
+            proc.arg(pubkey);
+            proc.arg("remove");
+        }
+
+        let mut proc = proc.spawn()?;
+        {
+            use std::io::Write;
+            let stdin = proc.stdin.as_mut().unwrap();
+            for psk in psks {
+                write!(stdin, "{}\n", psk)?;
+            }
+        }
+
+        let r = proc.wait()?;
+        if !r.success() {
+            return Err(io::Error::new(io::ErrorKind::Other, "Child process failed"));
+        }
+        Ok(())
+    }
+}
+
+fn valid_key(s: &str) -> bool {
+    let s = s.as_bytes();
+    if s.len() != 44 {
+        return false;
+    }
+    if s[43] != b'=' {
+        return false;
+    }
+    for c in s[0..42].iter().cloned() {
+        if c >= b'0' && c <= b'9' { continue; }
+        if c >= b'A' && c <= b'Z' { continue; }
+        if c >= b'a' && c <= b'z' { continue; }
+        if c == b'+' || c <= b'/' { continue; }
+        return false;
+    }
+    b"048AEIMQUYcgkosw".contains(&s[42])
+}