isb-daemon 1.0.0

//! Who is a superadmin ([`crate::auth::superadmin`]) on this daemon: a
//! superadmin token, a tailnet identity on `--superadmin-tailnet`, or a
//! verified Cloudflare Access identity on `--superadmin-access`. Nothing
//! else grants it. One gate serves the tool endpoints (through the authn
//! hook) and the identity endpoints (`/api/v1/auth/*`).

use std::sync::Arc;

use serde_json::{Value, json};

use crate::auth::agent_identities::AgentWays;
use crate::auth::{AuthStore, Principal, Superadmin, SuperadminSource};
use crate::error::{Error, Result};
use crate::server::access::{ASSERTION_HEADER, AccessValidator, Identity};
use crate::server::http::{Peer, Request};
use crate::server::tailnet::{Tailnet, host_only};
use crate::server::{Registry, Tool};

/// `--superadmin-access`: Access emails and service-token client ids.
#[derive(Debug, Clone, PartialEq, Eq, Default)]
pub struct AccessAllowList {
    pub emails: Vec<String>,
    pub client_ids: Vec<String>,
}

impl AccessAllowList {
    /// Comma-separated; an entry with `@` is an email, else a service
    /// token's client id. Exact matches only: no wildcards or domains.
    pub fn parse(list: &str) -> Result<AccessAllowList> {
        let mut a = AccessAllowList::default();
        for e in list.split(',').map(str::trim).filter(|e| !e.is_empty()) {
            if e.contains(['*', '?', ' ', '\t']) || e.starts_with('@') || e.ends_with('@') {
                return Err(Error::invalid(format!(
                    "--superadmin-access: {e:?}: exact emails or service token client ids only"
                )));
            }
            if e.contains('@') {
                a.emails.push(e.to_ascii_lowercase());
            } else {
                a.client_ids.push(e.to_string());
            }
        }
        if a.emails.is_empty() && a.client_ids.is_empty() {
            return Err(Error::invalid(
                "--superadmin-access needs at least one email or service token client id",
            ));
        }
        Ok(a)
    }

    /// A user by email (case-insensitively); a service token by client id.
    pub fn admits(&self, id: &Identity) -> bool {
        match (&id.email, &id.common_name) {
            (Some(e), _) => self.emails.iter().any(|x| x.eq_ignore_ascii_case(e)),
            (None, Some(cn)) => self.client_ids.iter().any(|x| x == cn),
            (None, None) => false,
        }
    }

    pub fn entries(&self) -> Vec<String> {
        self.emails
            .iter()
            .chain(&self.client_ids)
            .cloned()
            .collect()
    }
}

/// What the gate makes of a request.
pub enum Resolved {
    /// Not a superadmin credential: judge the request as before.
    None,
    /// A superadmin token that is not valid.
    Refused,
    Superadmin(Arc<Superadmin>),
}

pub struct Gate {
    store: Arc<AuthStore>,
    tailnet: Option<Tailnet>,
    /// The tailnet `--listen` addresses (what lets a tailnet peer in at all).
    tailnet_listens: Vec<String>,
    /// The validator of the listeners Access guards, and the `Host` names an
    /// Access agent's request may carry (empty: no public URL, not checked).
    access_agents: Option<(Arc<AccessValidator>, Vec<String>)>,
    /// The Access validator of the loopback listeners, the allow list, and
    /// the `Host` names an Access superadmin's request may carry.
    access: Option<(Arc<AccessValidator>, AccessAllowList, Vec<String>)>,
}

impl Gate {
    pub fn new(
        store: Arc<AuthStore>,
        tailnet: Option<Tailnet>,
        access: Option<(Arc<AccessValidator>, AccessAllowList, Vec<String>)>,
    ) -> Gate {
        let access = access.map(|(v, a, hosts)| {
            let mut hosts: Vec<String> = hosts.iter().map(|h| host_only(h)).collect();
            hosts.sort();
            hosts.dedup();
            (v, a, hosts)
        });
        Gate {
            store,
            tailnet,
            tailnet_listens: Vec::new(),
            access_agents: None,
            access,
        }
    }

    /// Let orgs' tailnet and Access agent identities in
    /// ([`crate::auth::agent_identities`]): the tailnet `--listen`
    /// addresses, and Access's validator with the `Host` names to allow.
    pub fn with_agents(
        mut self,
        tailnet_listens: Vec<String>,
        access: Option<(Arc<AccessValidator>, Vec<String>)>,
    ) -> Gate {
        self.tailnet_listens = tailnet_listens;
        self.access_agents = access.map(|(v, hosts)| {
            let mut hosts: Vec<String> = hosts.iter().map(|h| host_only(h)).collect();
            hosts.sort();
            hosts.dedup();
            (v, hosts)
        });
        self
    }

    /// Which agent identities can reach this server at all.
    pub fn agent_ways(&self) -> AgentWays {
        AgentWays {
            tailnet_listen: if self.tailnet.is_some() {
                self.tailnet_listens.clone()
            } else {
                Vec::new()
            },
            access: self.access_agents.is_some(),
            public_url: None,
            superadmin_access: self
                .access_list()
                .map(AccessAllowList::entries)
                .unwrap_or_default(),
            superadmin_tailnet: self
                .tailnet
                .as_ref()
                .map(|t| t.allow().entries())
                .unwrap_or_default(),
        }
    }

    /// The agent identity behind `req`, if an org maps it: a verified
    /// Access identity (`id`, else the request's own assertion) on a
    /// loopback listener Access guards, or a tailnet peer, as tailscaled
    /// says. A bearer token decides on its own, so it is not asked here.
    /// Superadmin sources are judged first, by [`Gate::resolve`].
    pub fn agent(&self, req: &Request, id: Option<&Identity>) -> Option<Principal> {
        if req.header("authorization").is_some() {
            return None;
        }
        let looked = if matches!(&req.peer, Peer::Tcp(a) if a.ip().is_loopback()) {
            let (v, hosts) = self.access_agents.as_ref()?;
            let verified;
            let id = match id {
                Some(id) => id,
                None => {
                    let t = req.header(ASSERTION_HEADER)?.trim();
                    verified = v.validate(t).ok()?;
                    &verified
                }
            };
            if !hosts.is_empty() {
                let host = req.header("host").map(host_only).unwrap_or_default();
                if !hosts.contains(&host) {
                    eprintln!(
                        "isb serve: Access agent {} sent Host {host:?}, not one of this server's names; not an agent",
                        id.name()
                    );
                    return None;
                }
            }
            self.store
                .principal_for_access_agent(id.email.as_deref(), id.common_name.as_deref())
        } else {
            let w = self.tailnet.as_ref()?.identify(req)?;
            self.store.principal_for_tailnet(&w.login, &w.node, &w.tags)
        };
        looked.unwrap_or_else(|e| {
            eprintln!("isb serve: agent identities: {e}");
            None
        })
    }

    pub fn tailnet(&self) -> Option<&Tailnet> {
        self.tailnet.as_ref()
    }

    pub fn access_list(&self) -> Option<&AccessAllowList> {
        self.access.as_ref().map(|(_, a, _)| a)
    }

    /// `id` is the Access identity the listener already verified, if any.
    /// A bearer superadmin token decides alone; any other bearer token is
    /// not this gate's. Then Access, then the tailnet.
    pub fn resolve(&self, req: &Request, id: Option<&Identity>) -> Resolved {
        if let Some(a) = req.header("authorization") {
            let token = a
                .trim()
                .split_once(' ')
                .filter(|(s, _)| s.eq_ignore_ascii_case("bearer"))
                .map(|(_, t)| t.trim());
            return match token {
                Some(t) if t.starts_with(crate::auth::secret::TokenKind::Superadmin.prefix()) => {
                    match self.store.authenticate_superadmin_token(t) {
                        Ok(Some(info)) => Resolved::Superadmin(Arc::new(Superadmin::synthetic(
                            SuperadminSource::Token {
                                id: info.id,
                                name: info.name,
                            },
                        ))),
                        Ok(None) => Resolved::Refused,
                        Err(e) => {
                            eprintln!("isb serve: superadmin token: {e}");
                            Resolved::Refused
                        }
                    }
                }
                _ => Resolved::None,
            };
        }
        if let Some(s) = self.access_superadmin(req, id) {
            return Resolved::Superadmin(s);
        }
        if let Some(w) = self.tailnet.as_ref().and_then(|t| t.superadmin(req)) {
            let source = SuperadminSource::Tailnet {
                login: w.login.clone(),
                node: w.node,
                tags: w.tags.clone(),
            };
            let as_user = if w.tags.is_empty() {
                Some(w.login.as_str())
            } else {
                None
            };
            return Resolved::Superadmin(Arc::new(self.acting_as(source, as_user)));
        }
        Resolved::None
    }

    /// Only from a verified assertion, on the loopback listeners Access
    /// guards.
    fn access_superadmin(&self, req: &Request, id: Option<&Identity>) -> Option<Arc<Superadmin>> {
        let (v, allow, hosts) = self.access.as_ref()?;
        let loopback = matches!(&req.peer, Peer::Tcp(a) if a.ip().is_loopback());
        if !loopback {
            return None;
        }
        let verified;
        let id = match id {
            Some(id) => id,
            None => {
                let t = req.header(ASSERTION_HEADER)?.trim();
                verified = v.validate(t).ok()?;
                &verified
            }
        };
        if !allow.admits(id) {
            return None;
        }
        let host = req.header("host").map(host_only).unwrap_or_default();
        if !hosts.contains(&host) {
            eprintln!(
                "isb serve: Access superadmin {} sent Host {host:?}, not one of this server's names; not a superadmin",
                id.name()
            );
            return None;
        }
        let source = SuperadminSource::Access {
            name: id.name().to_string(),
            service_token: id.is_service_token(),
        };
        Some(Arc::new(self.acting_as(source, id.email.as_deref())))
    }

    /// As the enabled isb user with this email, else synthetic.
    fn acting_as(&self, source: SuperadminSource, email: Option<&str>) -> Superadmin {
        let user = email
            .and_then(|e| self.store.user_by_email(e).ok().flatten())
            .filter(|u| !u.disabled);
        match user {
            Some(u) => Superadmin::as_user(source.clone(), u, &self.store)
                .unwrap_or_else(|_| Superadmin::synthetic(source)),
            None => Superadmin::synthetic(source),
        }
    }
}

/// Tools for superadmins only (not platform admins): the host itself, and
/// what reaches further into its kernel (nesting for an org's workspace).
pub const TOOLS: &[&str] = &[
    "host_inventory",
    "host_policy",
    "superadmin_token_list",
    "superadmin_token_revoke",
    "org_nesting",
];

/// A `--listen` address on the tailnet (it then binds without a tunnel).
pub fn is_tailnet_listen(addr: &str) -> bool {
    use std::net::ToSocketAddrs;
    addr.to_socket_addrs().is_ok_and(|mut a| {
        a.next()
            .is_some_and(|a| crate::server::tailnet::is_tailnet_ip(a.ip()))
    })
}

/// The public URL's host, for the `Host` checks.
fn public_host(url: &str) -> Option<String> {
    let rest = url.trim().split_once("://")?.1;
    let host = rest.split(['/', '?', '#']).next()?;
    (!host.is_empty()).then(|| host.to_string())
}

/// The gate `cfg` describes. Refuses `--superadmin-access` without Access or a
/// public URL (whose host the Access check needs).
pub fn gate(
    cfg: &super::ServeConfig,
    store: Arc<AuthStore>,
    access: Option<Arc<AccessValidator>>,
) -> Result<Gate> {
    let tailnet_listens: Vec<&String> =
        cfg.listen.iter().filter(|a| is_tailnet_listen(a)).collect();
    let public = cfg.public_url.as_deref().and_then(public_host);
    if cfg.superadmin_tailnet.is_some() && tailnet_listens.is_empty() {
        eprintln!(
            "isb serve: WARNING: --superadmin-tailnet without a tailnet --listen address: no tailnet peer can reach this daemon"
        );
    }
    // The tailnet check runs wherever a tailnet address is served: for the
    // superadmin allow list, and for orgs' agent identities.
    let tailnet = (cfg.superadmin_tailnet.is_some() || !tailnet_listens.is_empty()).then(|| {
        let allow = cfg.superadmin_tailnet.clone().unwrap_or_default();
        let mut hosts: Vec<String> = tailnet_listens.iter().map(|a| a.to_string()).collect();
        hosts.extend(crate::server::tailnet::self_names());
        hosts.extend(public.clone());
        crate::server::tailnet::Tailnet::new(allow, crate::server::tailnet::system_fetcher(), hosts)
    });
    let mut access_hosts: Vec<String> = public.iter().cloned().collect();
    access_hosts.extend(cfg.listen.iter().filter(|a| !is_tailnet_listen(a)).cloned());
    let agent_access = access.clone().map(|v| {
        let hosts = if public.is_some() {
            access_hosts
        } else {
            Vec::new()
        };
        (v, hosts)
    });
    let access = match (&cfg.superadmin_access, access) {
        (None, _) => None,
        (Some(_), None) => {
            return Err(Error::invalid(
                "--superadmin-access needs Cloudflare Access (CF_ACCESS_TEAM_DOMAIN and CF_ACCESS_AUD): it trusts only a verified assertion",
            ));
        }
        (Some(list), Some(v)) => {
            let Some(host) = public.clone() else {
                return Err(Error::invalid(
                    "--superadmin-access needs --public-url: an Access superadmin's request must name this server's host",
                ));
            };
            let mut hosts = vec![host];
            hosts.extend(cfg.listen.iter().filter(|a| !is_tailnet_listen(a)).cloned());
            Some((v, list.clone(), hosts))
        }
    };
    let listens = tailnet_listens.iter().map(|a| a.to_string()).collect();
    Ok(Gate::new(store, tailnet, access).with_agents(listens, agent_access))
}

/// What `host_policy` reports of the configuration (never a secret).
pub fn host_summary(cfg: &super::ServeConfig, gate: &Gate) -> Value {
    json!({
        "isb": env!("CARGO_PKG_VERSION"),
        "listen": cfg.listen,
        "socket": cfg.socket,
        "state_dir": cfg.state_dir,
        "public_url": cfg.public_url,
        "access": cfg.access.as_ref().map(|(team, aud)| json!({"team_domain": team, "aud": aud})),
        "allow_unauthenticated": cfg.allow_unauthenticated,
        "tools": {"allow": cfg.remote_tools.allow, "deny": cfg.remote_tools.deny},
        "policy": {
            "allow_privileged": cfg.policy.allow_privileged,
            "allow_raw": cfg.policy.allow_raw,
            "bind_roots": cfg.policy.bind_roots,
            "publish_addresses": cfg.policy.publish_addresses,
            "any_instance": cfg.policy.any_instance,
        },
        "superadmin": {
            "socket": cfg.socket,
            "tokens": true,
            "tailnet": cfg.superadmin_tailnet.as_ref().and(gate.tailnet()).map(|t| t.allow().entries()),
            "tailnet_hosts": gate.tailnet().map(|t| t.hosts().to_vec()),
            "access": gate.access_list().map(AccessAllowList::entries),
        },
    })
}

/// Say at start-up which sources grant superadmin.
pub fn announce(cfg: &super::ServeConfig, gate: &Gate, store: &AuthStore) {
    let mut v = vec![format!("the unix socket {}", cfg.socket.display())];
    if !cfg.listen.is_empty() {
        let n = store.list_superadmin_tokens().map(|t| t.len()).unwrap_or(0);
        v.push(format!(
            "superadmin tokens ({n}; minted on this host with `isb token create NAME --superadmin`)"
        ));
    }
    if let Some(t) = cfg.superadmin_tailnet.as_ref().and(gate.tailnet()) {
        v.push(format!(
            "tailnet identities {} (Host: {})",
            t.allow().entries().join(", "),
            t.hosts().join(", ")
        ));
    }
    if let Some(a) = gate.access_list() {
        v.push(format!(
            "Cloudflare Access identities {}",
            a.entries().join(", ")
        ));
    }
    eprintln!("isb serve: superadmins: {}", v.join("; "));
}

/// The superadmin-only tools.
pub(super) fn register(r: &mut Registry, d: Arc<super::Daemon>) -> Result<()> {
    let ro = json!({"readOnlyHint": true, "openWorldHint": false});
    let destructive = json!({"destructiveHint": true, "openWorldHint": false});
    let empty = || json!({"type": "object", "properties": {"org": {"type": "string"}}, "additionalProperties": false});
    let dd = d.clone();
    r.register(
        Tool::new(
            "host_inventory",
            "Every incus project and instance on the host, isb's or not: projects with the org each one is (if any); instances with project, type, status, addresses, and isb's labels (stack, owner). Superadmins only.",
            empty(),
            move |_a, _c| inventory(&dd),
        )
        .title("Host inventory")
        .annotations(ro.clone()),
    )?;
    let dd = d.clone();
    r.register(
        Tool::new(
            "host_policy",
            "How this daemon serves: listen addresses, Cloudflare Access, the tools remote callers see, what a remote caller's specs may ask for (bind roots, publish addresses, privileged, raw, any instance), and every superadmin source with its allow lists. Superadmins only.",
            empty(),
            move |_a, _c| {
                let mut v = dd.host.clone();
                v["superadmin"]["token_count"] =
                    json!(dd.users.list_superadmin_tokens().map(|t| t.len()).unwrap_or(0));
                Ok(v)
            },
        )
        .title("Host policy")
        .annotations(ro.clone()),
    )?;
    let dd = d.clone();
    r.register(
        Tool::new(
            "superadmin_token_list",
            "Superadmin tokens: id, name, created, last used, expiry (never the token). They are minted only on the host: isb token create NAME --superadmin. Superadmins only.",
            empty(),
            move |_a, _c| Ok(json!({"tokens": dd.users.list_superadmin_tokens()?})),
        )
        .title("Superadmin tokens")
        .annotations(ro),
    )?;
    let dd = d;
    r.register(
        Tool::new(
            "superadmin_token_revoke",
            "Revoke a superadmin token by id; it stops working at once. Superadmins only.",
            json!({"type": "object", "properties": {"id": {"type": "integer"}, "org": {"type": "string"}}, "required": ["id"], "additionalProperties": false}),
            move |a, _c| {
                let id = a
                    .get("id")
                    .and_then(Value::as_i64)
                    .ok_or_else(|| Error::invalid("id: an integer"))?;
                let t = dd.users.superadmin_token(id)?;
                dd.users.revoke_superadmin_token(id)?;
                Ok(json!({"revoked": t}))
            },
        )
        .title("Revoke a superadmin token")
        .annotations(destructive),
    )?;
    Ok(())
}

fn inventory(d: &super::Daemon) -> Result<Value> {
    let projects = d.client.get("/1.0/projects?recursion=1")?;
    let projects: Vec<Value> = projects
        .as_array()
        .map(|a| {
            a.iter()
                .map(|p| {
                    let name = p["name"].as_str().unwrap_or("");
                    json!({
                        "name": name,
                        "description": p["description"],
                        "org": crate::org::OrgId::from_incus_project(name).map(|o| o.to_string()),
                        "instances": p["used_by"].as_array().map(|u| u.iter().filter(|x| x.as_str().is_some_and(|s| s.starts_with("/1.0/instances/"))).count()).unwrap_or(0),
                    })
                })
                .collect()
        })
        .unwrap_or_default();
    let instances = d
        .client
        .get("/1.0/instances?recursion=2&all-projects=true")?;
    let instances: Vec<Value> = instances
        .as_array()
        .map(|a| {
            a.iter()
                .map(|i| {
                    let project = i["project"].as_str().unwrap_or("default");
                    let cfg = &i["config"];
                    let label = |k: &str| cfg.get(format!("user.{k}")).cloned().unwrap_or(Value::Null);
                    let addresses: Vec<String> = i["state"]["network"]
                        .as_object()
                        .map(|n| {
                            n.iter()
                                .filter(|(k, _)| k.as_str() != "lo")
                                .flat_map(|(_, v)| v["addresses"].as_array().cloned().unwrap_or_default())
                                .filter(|a| a["scope"] == "global")
                                .filter_map(|a| a["address"].as_str().map(String::from))
                                .collect()
                        })
                        .unwrap_or_default();
                    let stack = label("isb.stack");
                    let owner = label(super::LABEL_OWNER);
                    json!({
                        "name": i["name"],
                        "project": project,
                        "org": crate::org::OrgId::from_incus_project(project).map(|o| o.to_string()),
                        "type": i["type"],
                        "status": i["status"],
                        "created_at": i["created_at"],
                        "image": cfg.get("image.description").cloned().unwrap_or(Value::Null),
                        "addresses": addresses,
                        "stack": stack,
                        "owner": owner,
                        "managed": !stack.is_null() || !owner.is_null(),
                    })
                })
                .collect()
        })
        .unwrap_or_default();
    Ok(json!({"projects": projects, "instances": instances}))
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::auth::AuthConfig;
    use crate::server::access::tests as at;
    use crate::server::tailnet::{AllowList, Whois, WhoisFetcher};
    use serde_json::json;

    fn req(peer: &str, headers: &[(&str, &str)]) -> Request {
        Request {
            method: "GET".into(),
            path: "/mcp".into(),
            query: None,
            headers: headers
                .iter()
                .map(|(k, v)| (k.to_string(), v.to_string()))
                .collect(),
            body: Vec::new(),
            peer: Peer::Tcp(peer.parse().unwrap()),
        }
    }

    fn store() -> Arc<AuthStore> {
        let c = AuthConfig {
            password_cost: crate::auth::secret::PasswordCost::insecure_fast(),
            ..Default::default()
        };
        Arc::new(AuthStore::in_memory(c).unwrap())
    }

    fn label(r: Resolved) -> Option<String> {
        match r {
            Resolved::Superadmin(s) => Some(s.label()),
            _ => None,
        }
    }

    #[test]
    fn access_allow_lists() {
        assert!(AccessAllowList::parse("").is_err());
        assert!(AccessAllowList::parse("*@example.com").is_err());
        assert!(AccessAllowList::parse("@example.com").is_err());
        let a = AccessAllowList::parse("Alice@Example.com, abc123.access").unwrap();
        let id = |email: Option<&str>, cn: Option<&str>| Identity {
            email: email.map(String::from),
            sub: "s".into(),
            common_name: cn.map(String::from),
        };
        assert!(a.admits(&id(Some("alice@example.com"), None)));
        assert!(a.admits(&id(Some("ALICE@example.com"), None)));
        assert!(!a.admits(&id(Some("bob@example.com"), None)));
        assert!(!a.admits(&id(Some("alice@example.com.evil"), None)));
        assert!(a.admits(&id(None, Some("abc123.access"))));
        assert!(!a.admits(&id(None, Some("other.access"))));
        // A service token's id never matches as an email, nor the reverse.
        let b = AccessAllowList::parse("alice@example.com").unwrap();
        assert!(!b.admits(&id(None, Some("alice@example.com"))));
    }

    #[test]
    fn tokens_decide_alone() {
        let s = store();
        let t = s.create_superadmin_token("agent", None).unwrap();
        let g = Gate::new(s.clone(), None, None);
        let auth = format!("Bearer {}", t.token);
        assert_eq!(
            label(g.resolve(&req("127.0.0.1:1", &[("Authorization", &auth)]), None)).as_deref(),
            Some("token:agent")
        );
        let bad = format!("Bearer {}x", t.token);
        assert!(matches!(
            g.resolve(&req("127.0.0.1:1", &[("Authorization", &bad)]), None),
            Resolved::Refused
        ));
        // An ordinary API token is not the gate's.
        assert!(matches!(
            g.resolve(
                &req("127.0.0.1:1", &[("Authorization", "Bearer isb_tok_x")]),
                None
            ),
            Resolved::None
        ));
    }

    #[test]
    fn access_needs_a_verified_listed_identity_and_this_host() {
        let s = store();
        let alice = s
            .create_user("alice@example.com", "Alice", None, false)
            .unwrap();
        let (v, _) = at::validator();
        let g = Gate::new(
            s.clone(),
            None,
            Some((
                Arc::new(v),
                AccessAllowList::parse("alice@example.com,svc.access").unwrap(),
                vec!["https://isb.example.com".replace("https://", "")],
            )),
        );
        let token = at::sign(&at::header(), &at::claims());
        let host = ("Host", "isb.example.com");
        let ok = req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", &token), host]);
        match g.resolve(&ok, None) {
            Resolved::Superadmin(sa) => {
                assert_eq!(sa.label(), "access:alice@example.com");
                // Acts as the isb user with that email.
                assert_eq!(sa.principal.user.id, alice.id);
            }
            _ => panic!("expected a superadmin"),
        }
        // A forged (unsigned) assertion.
        let forged = req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", "a.b.c"), host]);
        assert!(label(g.resolve(&forged, None)).is_none());
        // Another email.
        let mut c = at::claims();
        c["email"] = json!("bob@example.com");
        let bob = at::sign(&at::header(), &c);
        assert!(
            label(g.resolve(
                &req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", &bob), host]),
                None
            ))
            .is_none()
        );
        // DNS rebinding: another Host.
        let evil = req(
            "127.0.0.1:1",
            &[
                ("Cf-Access-Jwt-Assertion", &token),
                ("Host", "evil.example"),
            ],
        );
        assert!(label(g.resolve(&evil, None)).is_none());
        // Off the loopback listeners Access guards.
        let tail = req("100.64.0.1:1", &[("Cf-Access-Jwt-Assertion", &token), host]);
        assert!(label(g.resolve(&tail, None)).is_none());
        // A service token by client id, synthetic.
        let mut c = at::claims();
        c.as_object_mut().unwrap().remove("email");
        c["common_name"] = json!("svc.access");
        let svc = at::sign(&at::header(), &c);
        match g.resolve(
            &req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", &svc), host]),
            None,
        ) {
            Resolved::Superadmin(sa) => {
                assert_eq!(sa.label(), "access:svc.access");
                assert!(!sa.has_account());
            }
            _ => panic!("expected a superadmin"),
        }
    }

    #[test]
    fn tailnet_acts_as_the_user_or_synthetic() {
        let s = store();
        let me = s.create_user("me@example.com", "Me", None, false).unwrap();
        let fetch: WhoisFetcher = Arc::new(|p: std::net::SocketAddr| {
            Ok(match p.ip().to_string().as_str() {
                "100.64.0.1" => Whois {
                    login: "me@example.com".into(),
                    node: "laptop.t.ts.net".into(),
                    tags: vec![],
                },
                _ => Whois {
                    login: "tagged-devices".into(),
                    node: "agent.t.ts.net".into(),
                    tags: vec!["tag:agents".into()],
                },
            })
        });
        let t = Tailnet::new(
            AllowList::parse("me@example.com,tag:agents").unwrap(),
            fetch,
            vec!["100.86.22.100".into()],
        );
        let g = Gate::new(s, Some(t), None);
        let host = ("Host", "100.86.22.100:18995");
        match g.resolve(&req("100.64.0.1:1", &[host]), None) {
            Resolved::Superadmin(sa) => {
                assert_eq!(sa.label(), "tailnet:me@example.com");
                assert_eq!(sa.principal.user.id, me.id);
            }
            _ => panic!(),
        }
        match g.resolve(&req("100.64.0.2:1", &[host]), None) {
            Resolved::Superadmin(sa) => {
                assert_eq!(sa.label(), "tailnet:agent.t.ts.net");
                assert!(!sa.has_account());
            }
            _ => panic!(),
        }
        // A bearer token takes the request away from the tailnet.
        assert!(matches!(
            g.resolve(
                &req(
                    "100.64.0.1:1",
                    &[host, ("Authorization", "Bearer isb_tok_x")]
                ),
                None
            ),
            Resolved::None
        ));
    }

    fn agent_store() -> (Arc<AuthStore>, crate::org::OrgId, crate::org::OrgId) {
        let s = store();
        let acme = crate::org::OrgId::new("acme").unwrap();
        let beta = crate::org::OrgId::new("beta").unwrap();
        s.ensure_org(&acme).unwrap();
        s.ensure_org(&beta).unwrap();
        (s, acme, beta)
    }

    #[test]
    fn tailnet_agents_are_pinned_to_the_orgs_that_map_them() {
        use crate::auth::Role;
        use crate::auth::agent_identities::AgentKind;
        let (s, acme, beta) = agent_store();
        let map = |o: &crate::org::OrgId, subj: &str, r| {
            s.set_agent_identity(o, AgentKind::Tailnet, subj, r, "", "t")
                .unwrap()
        };
        map(&acme, "tag:agents", Role::Member);
        map(&beta, "me@example.com", Role::Viewer);
        let fetch: WhoisFetcher = Arc::new(|p: std::net::SocketAddr| {
            Ok(match p.ip().to_string().as_str() {
                "100.64.0.1" => Whois {
                    login: "me@example.com".into(),
                    node: "laptop.t.ts.net".into(),
                    tags: vec![],
                },
                "100.64.0.2" => Whois {
                    login: "tagged-devices".into(),
                    node: "bot.t.ts.net".into(),
                    tags: vec!["tag:agents".into()],
                },
                // A tagged node owned by the mapped login.
                "100.64.0.3" => Whois {
                    login: "me@example.com".into(),
                    node: "owned.t.ts.net".into(),
                    tags: vec!["tag:other".into()],
                },
                _ => Whois {
                    login: "stranger@example.com".into(),
                    node: "x.t.ts.net".into(),
                    tags: vec![],
                },
            })
        });
        // No superadmin allow list at all: agents still resolve.
        let t = Tailnet::new(AllowList::default(), fetch, vec!["100.86.22.100".into()]);
        let g = Gate::new(s, Some(t), None).with_agents(vec!["100.86.22.100:18995".into()], None);
        assert_eq!(g.agent_ways().tailnet_listen, vec!["100.86.22.100:18995"]);
        let host = ("Host", "100.86.22.100:18995");
        let who = |peer: &str, h: &[(&str, &str)]| g.agent(&req(peer, h), None);
        // An untagged node by login: viewer in beta only.
        let p = who("100.64.0.1:1", &[host]).unwrap();
        assert_eq!(p.user.email, "tailnet:me@example.com");
        assert_eq!(p.orgs, vec![(beta.clone(), Role::Viewer)]);
        assert!(p.role_in(&acme).is_none() && !p.platform_admin && p.user.id == 0);
        // A tagged node by its tag: member in acme only.
        let p = who("100.64.0.2:1", &[host]).unwrap();
        assert_eq!(p.user.email, "tailnet:bot.t.ts.net");
        assert_eq!(p.orgs, vec![(acme, Role::Member)]);
        // A tagged node is never its owner's login.
        assert!(who("100.64.0.3:1", &[host]).is_none());
        assert!(who("100.64.0.9:1", &[host]).is_none());
        // Not a tailnet address, or another Host (DNS rebinding).
        assert!(who("192.168.1.5:1", &[host]).is_none());
        assert!(who("100.64.0.1:1", &[("Host", "evil.example")]).is_none());
        assert!(who("100.64.0.1:1", &[]).is_none());
        // A bearer token takes the request away from the tailnet.
        assert!(who("100.64.0.1:1", &[host, ("Authorization", "Bearer x")]).is_none());
        // And a tailnet agent is no superadmin.
        assert!(matches!(
            g.resolve(&req("100.64.0.1:1", &[host]), None),
            Resolved::None
        ));
        assert!(
            g.tailnet()
                .unwrap()
                .superadmin(&req("100.64.0.1:1", &[host]))
                .is_none()
        );
    }

    #[test]
    fn access_agents_need_a_verified_mapped_identity_that_is_not_a_user() {
        use crate::auth::Role;
        use crate::auth::agent_identities::AgentKind;
        let (s, acme, _beta) = agent_store();
        let map = |subj: &str| {
            s.set_agent_identity(&acme, AgentKind::Access, subj, Role::Admin, "", "t")
                .unwrap()
        };
        map("svc.access");
        map("alice@example.com");
        // The isb user's email acts as that user (the authn hook's job); the
        // gate never makes it an agent.
        s.create_user("alice@example.com", "Alice", None, false)
            .ok();
        let (v, _) = at::validator();
        let g = Gate::new(s, None, None).with_agents(
            Vec::new(),
            Some((Arc::new(v), vec!["isb.example.com".into()])),
        );
        assert!(g.agent_ways().access);
        let host = ("Host", "isb.example.com");
        let token = at::sign(&at::header(), &at::claims());
        // The test claims' email is alice's: an isb user, so no agent.
        assert!(
            g.agent(
                &req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", &token), host]),
                None
            )
            .is_none()
        );
        let mut c = at::claims();
        c.as_object_mut().unwrap().remove("email");
        c["common_name"] = json!("svc.access");
        let svc = at::sign(&at::header(), &c);
        let ok = req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", &svc), host]);
        let p = g.agent(&ok, None).unwrap();
        assert_eq!(p.user.email, "access:svc.access");
        assert_eq!(p.orgs, vec![(acme.clone(), Role::Admin)]);
        // An unmapped client id, a forged assertion, a foreign Host, a
        // non-loopback peer.
        c["common_name"] = json!("other.access");
        let other = at::sign(&at::header(), &c);
        assert!(
            g.agent(
                &req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", &other), host]),
                None
            )
            .is_none()
        );
        assert!(
            g.agent(
                &req("127.0.0.1:1", &[("Cf-Access-Jwt-Assertion", "a.b.c"), host]),
                None
            )
            .is_none()
        );
        assert!(
            g.agent(
                &req(
                    "127.0.0.1:1",
                    &[("Cf-Access-Jwt-Assertion", &svc), ("Host", "evil.example")]
                ),
                None
            )
            .is_none()
        );
        assert!(
            g.agent(
                &req("100.64.0.1:1", &[("Cf-Access-Jwt-Assertion", &svc), host]),
                None
            )
            .is_none()
        );
        // Never a superadmin.
        assert!(matches!(g.resolve(&ok, None), Resolved::None));
    }
}