add support for arbitrary proxies

src/database.rs

@@ -46,6 +46,8 @@ pub struct Config {
     allow_federation: bool,
     #[serde(default = "false_fn")]
     pub allow_jaeger: bool,
+    #[serde(default)]
+    proxy: ProxyConfig,
     jwt_secret: Option<String>,
     #[serde(default = "Vec::new")]
     trusted_servers: Vec<Box<ServerName>>,
@@ -83,6 +85,125 @@ pub type Engine = abstraction::SledEngine;
 #[cfg(feature = "rocksdb")]
 pub type Engine = abstraction::RocksDbEngine;
 
+#[derive(Clone, Debug, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ProxyConfig {
+    None,
+    Global {
+        #[serde(deserialize_with = "crate::utils::deserialize_from_str")]
+        url: reqwest::Url,
+    },
+    ByDomain(Vec<PartialProxyConfig>),
+}
+impl ProxyConfig {
+    pub fn to_proxy(&self) -> Result<Option<reqwest::Proxy>> {
+        Ok(match self.clone() {
+            ProxyConfig::None => None,
+            ProxyConfig::Global { url } => Some(reqwest::Proxy::all(url)?),
+            ProxyConfig::ByDomain(proxies) => Some(reqwest::Proxy::custom(move |url| {
+                proxies.iter().find_map(|proxy| proxy.for_url(url)).cloned() // first matching proxy
+            })),
+        })
+    }
+}
+impl Default for ProxyConfig {
+    fn default() -> Self {
+        ProxyConfig::None
+    }
+}
+
+#[derive(Clone, Debug, Deserialize)]
+pub struct PartialProxyConfig {
+    #[serde(deserialize_with = "crate::utils::deserialize_from_str")]
+    url: reqwest::Url,
+    #[serde(default)]
+    include: Vec<WildCardedDomain>,
+    #[serde(default)]
+    exclude: Vec<WildCardedDomain>,
+}
+impl PartialProxyConfig {
+    pub fn for_url(&self, url: &reqwest::Url) -> Option<&reqwest::Url> {
+        let domain = url.domain()?;
+        let mut included_because = None; // most specific reason it was included
+        let mut excluded_because = None; // most specific reason it was excluded
+        if self.include.is_empty() {
+            // treat empty include list as `*`
+            included_because = Some(&WildCardedDomain::WildCard)
+        }
+        for wc_domain in &self.include {
+            if wc_domain.matches(domain) {
+                match included_because {
+                    Some(prev) if !wc_domain.more_specific_than(prev) => (),
+                    _ => included_because = Some(wc_domain),
+                }
+            }
+        }
+        for wc_domain in &self.exclude {
+            if wc_domain.matches(domain) {
+                match excluded_because {
+                    Some(prev) if !wc_domain.more_specific_than(prev) => (),
+                    _ => excluded_because = Some(wc_domain),
+                }
+            }
+        }
+        match (included_because, excluded_because) {
+            (Some(a), Some(b)) if a.more_specific_than(b) => Some(&self.url), // included for a more specific reason than excluded
+            (Some(_), None) => Some(&self.url),
+            _ => None,
+        }
+    }
+}
+
+/// A domain name, that optionally allows a * as its first subdomain.
+#[derive(Clone, Debug)]
+pub enum WildCardedDomain {
+    WildCard,
+    WildCarded(String),
+    Exact(String),
+}
+impl WildCardedDomain {
+    pub fn matches(&self, domain: &str) -> bool {
+        match self {
+            WildCardedDomain::WildCard => true,
+            WildCardedDomain::WildCarded(d) => domain.ends_with(d),
+            WildCardedDomain::Exact(d) => domain == d,
+        }
+    }
+    pub fn more_specific_than(&self, other: &Self) -> bool {
+        match (self, other) {
+            (WildCardedDomain::WildCard, WildCardedDomain::WildCard) => false,
+            (_, WildCardedDomain::WildCard) => true,
+            (WildCardedDomain::Exact(a), WildCardedDomain::WildCarded(_)) => other.matches(a),
+            (WildCardedDomain::WildCarded(a), WildCardedDomain::WildCarded(b)) => {
+                a != b && a.ends_with(b)
+            }
+            _ => false,
+        }
+    }
+}
+impl std::str::FromStr for WildCardedDomain {
+    type Err = std::convert::Infallible;
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        // maybe do some domain validation?
+        Ok(if s.starts_with("*.") {
+            WildCardedDomain::WildCarded(s[1..].to_owned())
+        } else if s == "*" {
+            WildCardedDomain::WildCarded("".to_owned())
+        } else {
+            WildCardedDomain::Exact(s.to_owned())
+        })
+    }
+}
+impl<'de> serde::de::Deserialize<'de> for WildCardedDomain {
+    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
+    where
+        D: serde::de::Deserializer<'de>,
+    {
+        crate::utils::deserialize_from_str(deserializer)
+    }
+}
+
+#[derive(Clone)]
 pub struct Database {
     pub globals: globals::Globals,
     pub users: users::Users,