Rename livekit_server to livekit_api (#24984)

The name `livekit_server` was a bit misleading as it is not a server and
gets built into both the client and server - the server code is in
`collab`.

Release Notes:

- N/A

crates/livekit_api/src/token.rs

@@ -0,0 +1,112 @@
+use anyhow::{anyhow, Result};
+use jsonwebtoken::{DecodingKey, EncodingKey, Header, Validation};
+use serde::{Deserialize, Serialize};
+use std::{
+    borrow::Cow,
+    ops::Add,
+    time::{Duration, SystemTime, UNIX_EPOCH},
+};
+
+const DEFAULT_TTL: Duration = Duration::from_secs(6 * 60 * 60); // 6 hours
+
+#[derive(Default, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct ClaimGrants<'a> {
+    pub iss: Cow<'a, str>,
+    pub sub: Option<Cow<'a, str>>,
+    pub iat: u64,
+    pub exp: u64,
+    pub nbf: u64,
+    pub jwtid: Option<Cow<'a, str>>,
+    pub video: VideoGrant<'a>,
+}
+
+#[derive(Default, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct VideoGrant<'a> {
+    pub room_create: Option<bool>,
+    pub room_join: Option<bool>,
+    pub room_list: Option<bool>,
+    pub room_record: Option<bool>,
+    pub room_admin: Option<bool>,
+    pub room: Option<Cow<'a, str>>,
+    pub can_publish: Option<bool>,
+    pub can_subscribe: Option<bool>,
+    pub can_publish_data: Option<bool>,
+    pub hidden: Option<bool>,
+    pub recorder: Option<bool>,
+}
+
+impl<'a> VideoGrant<'a> {
+    pub fn to_admin(room: &'a str) -> Self {
+        Self {
+            room_admin: Some(true),
+            room: Some(Cow::Borrowed(room)),
+            ..Default::default()
+        }
+    }
+
+    pub fn to_join(room: &'a str) -> Self {
+        Self {
+            room: Some(Cow::Borrowed(room)),
+            room_join: Some(true),
+            can_publish: Some(true),
+            can_subscribe: Some(true),
+            ..Default::default()
+        }
+    }
+
+    pub fn for_guest(room: &'a str) -> Self {
+        Self {
+            room: Some(Cow::Borrowed(room)),
+            room_join: Some(true),
+            can_publish: Some(false),
+            can_subscribe: Some(true),
+            ..Default::default()
+        }
+    }
+}
+
+pub fn create(
+    api_key: &str,
+    secret_key: &str,
+    identity: Option<&str>,
+    video_grant: VideoGrant,
+) -> Result<String> {
+    if video_grant.room_join.is_some() && identity.is_none() {
+        Err(anyhow!(
+            "identity is required for room_join grant, but it is none"
+        ))?;
+    }
+
+    let now = SystemTime::now();
+
+    let claims = ClaimGrants {
+        iss: Cow::Borrowed(api_key),
+        sub: identity.map(Cow::Borrowed),
+        iat: now.duration_since(UNIX_EPOCH).unwrap().as_secs(),
+        exp: now
+            .add(DEFAULT_TTL)
+            .duration_since(UNIX_EPOCH)
+            .unwrap()
+            .as_secs(),
+        nbf: 0,
+        jwtid: identity.map(Cow::Borrowed),
+        video: video_grant,
+    };
+    Ok(jsonwebtoken::encode(
+        &Header::default(),
+        &claims,
+        &EncodingKey::from_secret(secret_key.as_ref()),
+    )?)
+}
+
+pub fn validate<'a>(token: &'a str, secret_key: &str) -> Result<ClaimGrants<'a>> {
+    let token = jsonwebtoken::decode(
+        token,
+        &DecodingKey::from_secret(secret_key.as_ref()),
+        &Validation::default(),
+    )?;
+
+    Ok(token.claims)
+}