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//! Module containing functionality related to BSON ObjectIds.
//! For more information, see the documentation for the [`ObjectId`] type.
use std::{
error,
fmt,
result,
str::FromStr,
sync::atomic::{AtomicUsize, Ordering},
};
#[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
use std::{convert::TryInto, time::SystemTime};
use hex::{self, FromHexError};
use once_cell::sync::Lazy;
use rand::{random, thread_rng, Rng};
const TIMESTAMP_SIZE: usize = 4;
const PROCESS_ID_SIZE: usize = 5;
const COUNTER_SIZE: usize = 3;
const TIMESTAMP_OFFSET: usize = 0;
const PROCESS_ID_OFFSET: usize = TIMESTAMP_OFFSET + TIMESTAMP_SIZE;
const COUNTER_OFFSET: usize = PROCESS_ID_OFFSET + PROCESS_ID_SIZE;
const MAX_U24: usize = 0xFF_FFFF;
static OID_COUNTER: Lazy<AtomicUsize> =
Lazy::new(|| AtomicUsize::new(thread_rng().gen_range(0..=MAX_U24)));
/// Errors that can occur during [`ObjectId`] construction and generation.
#[derive(Clone, Debug)]
#[non_exhaustive]
pub enum Error {
/// An invalid character was found in the provided hex string. Valid characters are: `0...9`,
/// `a...f`, or `A...F`.
#[non_exhaustive]
InvalidHexStringCharacter { c: char, index: usize, hex: String },
/// An [`ObjectId`]'s hex string representation must be an exactly 12-byte (24-char)
/// hexadecimal string.
#[non_exhaustive]
InvalidHexStringLength { length: usize, hex: String },
}
/// Alias for Result<T, oid::Error>.
pub type Result<T> = result::Result<T, Error>;
impl fmt::Display for Error {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
match self {
Error::InvalidHexStringCharacter { c, index, hex } => {
write!(
fmt,
"invalid character '{}' was found at index {} in the provided hex string: \
\"{}\"",
c, index, hex
)
}
Error::InvalidHexStringLength { length, hex } => {
write!(
fmt,
"provided hex string representation must be exactly 12 bytes, instead got: \
\"{}\", length {}",
hex, length
)
}
}
}
}
impl error::Error for Error {}
/// A wrapper around a raw 12-byte ObjectId.
///
/// ## `serde` integration
/// When serialized to BSON via `serde`, this type produces a BSON ObjectId. In non-BSON formats, it
/// will serialize to and deserialize from that format's equivalent of the [extended JSON representation](https://www.mongodb.com/docs/manual/reference/mongodb-extended-json/) of a BSON ObjectId.
///
/// [`ObjectId`]s can be deserialized from hex strings in all formats.
///
/// e.g.
/// ```rust
/// use serde::{Serialize, Deserialize};
/// use bson::oid::ObjectId;
///
/// #[derive(Serialize, Deserialize)]
/// struct Foo {
/// oid: ObjectId,
/// }
///
/// # fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
/// let f = Foo { oid: ObjectId::new() };
/// println!("bson: {}", bson::to_document(&f)?);
/// println!("json: {}", serde_json::to_string(&f)?);
/// # Ok(())
/// # }
/// ```
/// Produces the following output:
/// ```text
/// bson: { "oid": ObjectId("63ceed18f71dda7d8cf21e8e") }
/// json: {"oid":{"$oid":"63ceed18f71dda7d8cf21e8e"}}
/// ```
///
/// ### `serde_helpers`
/// The `bson` crate provides a number of useful helpers for serializing and deserializing
/// various types to and from different formats. For example, to serialize an
/// [`ObjectId`] as a hex string, you can use
/// [`crate::serde_helpers::serialize_object_id_as_hex_string`].
/// Check out the [`crate::serde_helpers`] module documentation for a list of all of the helpers
/// offered by the crate.
///
/// e.g.
/// ```rust
/// use serde::{Serialize, Deserialize};
/// use bson::oid::ObjectId;
///
/// #[derive(Serialize, Deserialize)]
/// struct Foo {
/// // Serializes as a BSON ObjectId or extJSON in non-BSON formats
/// oid: ObjectId,
///
/// // Serializes as a hex string in all formats
/// #[serde(serialize_with = "bson::serde_helpers::serialize_object_id_as_hex_string")]
/// oid_as_hex: ObjectId,
/// }
/// # fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
/// let f = Foo { oid: ObjectId::new(), oid_as_hex: ObjectId::new() };
/// println!("bson: {}", bson::to_document(&f)?);
/// println!("json: {}", serde_json::to_string(&f)?);
/// # Ok(())
/// # }
/// ```
/// Produces the following output:
/// ```text
/// bson: { "oid": ObjectId("63ceeffd37518221cdc6cda2"), "oid_as_hex": "63ceeffd37518221cdc6cda3" }
/// json: {"oid":{"$oid":"63ceeffd37518221cdc6cda2"},"oid_as_hex":"63ceeffd37518221cdc6cda3"}
/// ```
#[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Hash)]
pub struct ObjectId {
id: [u8; 12],
}
impl Default for ObjectId {
fn default() -> Self {
Self::new()
}
}
impl FromStr for ObjectId {
type Err = Error;
fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
Self::parse_str(s)
}
}
impl From<[u8; 12]> for ObjectId {
fn from(bytes: [u8; 12]) -> Self {
Self { id: bytes }
}
}
impl ObjectId {
/// Generates a new [`ObjectId`], represented in bytes.
/// See the [docs](http://www.mongodb.com/docs/manual/reference/object-id/)
/// for more information.
pub fn new() -> ObjectId {
let timestamp = ObjectId::gen_timestamp();
let process_id = ObjectId::gen_process_id();
let counter = ObjectId::gen_count();
let mut buf: [u8; 12] = [0; 12];
buf[TIMESTAMP_OFFSET..(TIMESTAMP_SIZE + TIMESTAMP_OFFSET)]
.clone_from_slice(×tamp[..TIMESTAMP_SIZE]);
buf[PROCESS_ID_OFFSET..(PROCESS_ID_SIZE + PROCESS_ID_OFFSET)]
.clone_from_slice(&process_id[..PROCESS_ID_SIZE]);
buf[COUNTER_OFFSET..(COUNTER_SIZE + COUNTER_OFFSET)]
.clone_from_slice(&counter[..COUNTER_SIZE]);
ObjectId::from_bytes(buf)
}
/// Constructs a new ObjectId wrapper around the raw byte representation.
pub const fn from_bytes(bytes: [u8; 12]) -> ObjectId {
ObjectId { id: bytes }
}
/// Creates an ObjectID using a 12-byte (24-char) hexadecimal string.
pub fn parse_str(s: impl AsRef<str>) -> Result<ObjectId> {
let s = s.as_ref();
let bytes: Vec<u8> = hex::decode(s.as_bytes()).map_err(|e| match e {
FromHexError::InvalidHexCharacter { c, index } => Error::InvalidHexStringCharacter {
c,
index,
hex: s.to_string(),
},
FromHexError::InvalidStringLength | FromHexError::OddLength => {
Error::InvalidHexStringLength {
length: s.len(),
hex: s.to_string(),
}
}
})?;
if bytes.len() != 12 {
Err(Error::InvalidHexStringLength {
length: s.len(),
hex: s.to_string(),
})
} else {
let mut byte_array: [u8; 12] = [0; 12];
byte_array[..].copy_from_slice(&bytes[..]);
Ok(ObjectId::from_bytes(byte_array))
}
}
/// Retrieves the timestamp from an [`ObjectId`].
pub fn timestamp(&self) -> crate::DateTime {
let mut buf = [0; 4];
buf.copy_from_slice(&self.id[0..4]);
let seconds_since_epoch = u32::from_be_bytes(buf);
// This doesn't overflow since u32::MAX * 1000 < i64::MAX
crate::DateTime::from_millis(seconds_since_epoch as i64 * 1000)
}
/// Returns the raw byte representation of an ObjectId.
pub const fn bytes(&self) -> [u8; 12] {
self.id
}
/// Convert this [`ObjectId`] to its hex string representation.
pub fn to_hex(self) -> String {
hex::encode(self.id)
}
/// Generates a new timestamp representing the current seconds since epoch.
/// Represented in Big Endian.
fn gen_timestamp() -> [u8; 4] {
#[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
let timestamp: u32 = (js_sys::Date::now() / 1000.0) as u32;
#[cfg(not(all(target_arch = "wasm32", target_os = "unknown")))]
let timestamp: u32 = SystemTime::now()
.duration_since(SystemTime::UNIX_EPOCH)
.expect("system clock is before 1970")
.as_secs()
.try_into()
.unwrap(); // will succeed until 2106 since timestamp is unsigned
timestamp.to_be_bytes()
}
/// Generate a random 5-byte array.
fn gen_process_id() -> [u8; 5] {
static BUF: Lazy<[u8; 5]> = Lazy::new(random);
*BUF
}
/// Gets an incremental 3-byte count.
/// Represented in Big Endian.
fn gen_count() -> [u8; 3] {
let u_counter = OID_COUNTER.fetch_add(1, Ordering::SeqCst);
// Mod result instead of OID_COUNTER to prevent threading issues.
let u = u_counter % (MAX_U24 + 1);
// Convert usize to writable u64, then extract the first three bytes.
let u_int = u as u64;
let buf = u_int.to_be_bytes();
let buf_u24: [u8; 3] = [buf[5], buf[6], buf[7]];
buf_u24
}
}
impl fmt::Display for ObjectId {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(&self.to_hex())
}
}
impl fmt::Debug for ObjectId {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("ObjectId").field(&self.to_hex()).finish()
}
}
#[cfg(test)]
use crate::tests::LOCK;
#[test]
fn count_generated_is_big_endian() {
let _guard = LOCK.run_exclusively();
let start = 1_122_866;
OID_COUNTER.store(start, Ordering::SeqCst);
// Test count generates correct value 1122866
let count_bytes = ObjectId::gen_count();
let mut buf: [u8; 4] = [0; 4];
buf[1..=COUNTER_SIZE].clone_from_slice(&count_bytes[..COUNTER_SIZE]);
let count = u32::from_be_bytes(buf);
assert_eq!(start as u32, count);
// Test OID formats count correctly as big endian
let oid = ObjectId::new();
assert_eq!(0x11u8, oid.bytes()[COUNTER_OFFSET]);
assert_eq!(0x22u8, oid.bytes()[COUNTER_OFFSET + 1]);
assert_eq!(0x33u8, oid.bytes()[COUNTER_OFFSET + 2]);
}
#[test]
fn test_counter_overflow_u24_max() {
let _guard = LOCK.run_exclusively();
let start = MAX_U24;
OID_COUNTER.store(start, Ordering::SeqCst);
let oid = ObjectId::new();
assert_eq!(0xFFu8, oid.bytes()[COUNTER_OFFSET]);
assert_eq!(0xFFu8, oid.bytes()[COUNTER_OFFSET + 1]);
assert_eq!(0xFFu8, oid.bytes()[COUNTER_OFFSET + 2]);
// Test counter overflows to 0 when set to MAX_24 + 1
let oid_new = ObjectId::new();
assert_eq!(0x00u8, oid_new.bytes()[COUNTER_OFFSET]);
assert_eq!(0x00u8, oid_new.bytes()[COUNTER_OFFSET + 1]);
assert_eq!(0x00u8, oid_new.bytes()[COUNTER_OFFSET + 2]);
}
#[test]
fn test_counter_overflow_usize_max() {
let _guard = LOCK.run_exclusively();
let start = usize::max_value();
OID_COUNTER.store(start, Ordering::SeqCst);
// Test counter overflows to u24_max when set to usize_max
let oid = ObjectId::new();
assert_eq!(0xFFu8, oid.bytes()[COUNTER_OFFSET]);
assert_eq!(0xFFu8, oid.bytes()[COUNTER_OFFSET + 1]);
assert_eq!(0xFFu8, oid.bytes()[COUNTER_OFFSET + 2]);
// Test counter overflows to 0 when set to usize_max + 1
let oid_new = ObjectId::new();
assert_eq!(0x00u8, oid_new.bytes()[COUNTER_OFFSET]);
assert_eq!(0x00u8, oid_new.bytes()[COUNTER_OFFSET + 1]);
assert_eq!(0x00u8, oid_new.bytes()[COUNTER_OFFSET + 2]);
}
#[cfg(test)]
mod test {
use time::macros::datetime;
#[test]
fn test_display() {
let id = super::ObjectId::parse_str("53e37d08776f724e42000000").unwrap();
assert_eq!(format!("{}", id), "53e37d08776f724e42000000")
}
#[test]
fn test_debug() {
let id = super::ObjectId::parse_str("53e37d08776f724e42000000").unwrap();
assert_eq!(
format!("{:?}", id),
"ObjectId(\"53e37d08776f724e42000000\")"
);
assert_eq!(
format!("{:#?}", id),
"ObjectId(\n \"53e37d08776f724e42000000\",\n)"
);
}
#[test]
fn test_timestamp() {
let id = super::ObjectId::parse_str("000000000000000000000000").unwrap();
// "Jan 1st, 1970 00:00:00 UTC"
assert_eq!(datetime!(1970-01-01 0:00 UTC), id.timestamp().to_time_0_3());
let id = super::ObjectId::parse_str("7FFFFFFF0000000000000000").unwrap();
// "Jan 19th, 2038 03:14:07 UTC"
assert_eq!(
datetime!(2038-01-19 3:14:07 UTC),
id.timestamp().to_time_0_3()
);
let id = super::ObjectId::parse_str("800000000000000000000000").unwrap();
// "Jan 19th, 2038 03:14:08 UTC"
assert_eq!(
datetime!(2038-01-19 3:14:08 UTC),
id.timestamp().to_time_0_3()
);
let id = super::ObjectId::parse_str("FFFFFFFF0000000000000000").unwrap();
// "Feb 7th, 2106 06:28:15 UTC"
assert_eq!(
datetime!(2106-02-07 6:28:15 UTC),
id.timestamp().to_time_0_3()
);
}
}