diff options
Diffstat (limited to 'third_party/rust/h2/src/hpack/encoder.rs')
-rw-r--r-- | third_party/rust/h2/src/hpack/encoder.rs | 721 |
1 files changed, 721 insertions, 0 deletions
diff --git a/third_party/rust/h2/src/hpack/encoder.rs b/third_party/rust/h2/src/hpack/encoder.rs new file mode 100644 index 0000000000..d121a2aaf5 --- /dev/null +++ b/third_party/rust/h2/src/hpack/encoder.rs @@ -0,0 +1,721 @@ +use super::table::{Index, Table}; +use super::{huffman, Header}; + +use bytes::{BufMut, BytesMut}; +use http::header::{HeaderName, HeaderValue}; + +#[derive(Debug)] +pub struct Encoder { + table: Table, + size_update: Option<SizeUpdate>, +} + +#[derive(Debug, Copy, Clone, Eq, PartialEq)] +enum SizeUpdate { + One(usize), + Two(usize, usize), // min, max +} + +impl Encoder { + pub fn new(max_size: usize, capacity: usize) -> Encoder { + Encoder { + table: Table::new(max_size, capacity), + size_update: None, + } + } + + /// Queues a max size update. + /// + /// The next call to `encode` will include a dynamic size update frame. + pub fn update_max_size(&mut self, val: usize) { + match self.size_update { + Some(SizeUpdate::One(old)) => { + if val > old { + if old > self.table.max_size() { + self.size_update = Some(SizeUpdate::One(val)); + } else { + self.size_update = Some(SizeUpdate::Two(old, val)); + } + } else { + self.size_update = Some(SizeUpdate::One(val)); + } + } + Some(SizeUpdate::Two(min, _)) => { + if val < min { + self.size_update = Some(SizeUpdate::One(val)); + } else { + self.size_update = Some(SizeUpdate::Two(min, val)); + } + } + None => { + if val != self.table.max_size() { + // Don't bother writing a frame if the value already matches + // the table's max size. + self.size_update = Some(SizeUpdate::One(val)); + } + } + } + } + + /// Encode a set of headers into the provide buffer + pub fn encode<I>(&mut self, headers: I, dst: &mut BytesMut) + where + I: IntoIterator<Item = Header<Option<HeaderName>>>, + { + let span = tracing::trace_span!("hpack::encode"); + let _e = span.enter(); + + self.encode_size_updates(dst); + + let mut last_index = None; + + for header in headers { + match header.reify() { + // The header has an associated name. In which case, try to + // index it in the table. + Ok(header) => { + let index = self.table.index(header); + self.encode_header(&index, dst); + + last_index = Some(index); + } + // The header does not have an associated name. This means that + // the name is the same as the previously yielded header. In + // which case, we skip table lookup and just use the same index + // as the previous entry. + Err(value) => { + self.encode_header_without_name( + last_index.as_ref().unwrap_or_else(|| { + panic!("encoding header without name, but no previous index to use for name"); + }), + &value, + dst, + ); + } + } + } + } + + fn encode_size_updates(&mut self, dst: &mut BytesMut) { + match self.size_update.take() { + Some(SizeUpdate::One(val)) => { + self.table.resize(val); + encode_size_update(val, dst); + } + Some(SizeUpdate::Two(min, max)) => { + self.table.resize(min); + self.table.resize(max); + encode_size_update(min, dst); + encode_size_update(max, dst); + } + None => {} + } + } + + fn encode_header(&mut self, index: &Index, dst: &mut BytesMut) { + match *index { + Index::Indexed(idx, _) => { + encode_int(idx, 7, 0x80, dst); + } + Index::Name(idx, _) => { + let header = self.table.resolve(index); + + encode_not_indexed(idx, header.value_slice(), header.is_sensitive(), dst); + } + Index::Inserted(_) => { + let header = self.table.resolve(index); + + assert!(!header.is_sensitive()); + + dst.put_u8(0b0100_0000); + + encode_str(header.name().as_slice(), dst); + encode_str(header.value_slice(), dst); + } + Index::InsertedValue(idx, _) => { + let header = self.table.resolve(index); + + assert!(!header.is_sensitive()); + + encode_int(idx, 6, 0b0100_0000, dst); + encode_str(header.value_slice(), dst); + } + Index::NotIndexed(_) => { + let header = self.table.resolve(index); + + encode_not_indexed2( + header.name().as_slice(), + header.value_slice(), + header.is_sensitive(), + dst, + ); + } + } + } + + fn encode_header_without_name( + &mut self, + last: &Index, + value: &HeaderValue, + dst: &mut BytesMut, + ) { + match *last { + Index::Indexed(..) + | Index::Name(..) + | Index::Inserted(..) + | Index::InsertedValue(..) => { + let idx = self.table.resolve_idx(last); + + encode_not_indexed(idx, value.as_ref(), value.is_sensitive(), dst); + } + Index::NotIndexed(_) => { + let last = self.table.resolve(last); + + encode_not_indexed2( + last.name().as_slice(), + value.as_ref(), + value.is_sensitive(), + dst, + ); + } + } + } +} + +impl Default for Encoder { + fn default() -> Encoder { + Encoder::new(4096, 0) + } +} + +fn encode_size_update(val: usize, dst: &mut BytesMut) { + encode_int(val, 5, 0b0010_0000, dst) +} + +fn encode_not_indexed(name: usize, value: &[u8], sensitive: bool, dst: &mut BytesMut) { + if sensitive { + encode_int(name, 4, 0b10000, dst); + } else { + encode_int(name, 4, 0, dst); + } + + encode_str(value, dst); +} + +fn encode_not_indexed2(name: &[u8], value: &[u8], sensitive: bool, dst: &mut BytesMut) { + if sensitive { + dst.put_u8(0b10000); + } else { + dst.put_u8(0); + } + + encode_str(name, dst); + encode_str(value, dst); +} + +fn encode_str(val: &[u8], dst: &mut BytesMut) { + if !val.is_empty() { + let idx = position(dst); + + // Push a placeholder byte for the length header + dst.put_u8(0); + + // Encode with huffman + huffman::encode(val, dst); + + let huff_len = position(dst) - (idx + 1); + + if encode_int_one_byte(huff_len, 7) { + // Write the string head + dst[idx] = 0x80 | huff_len as u8; + } else { + // Write the head to a placeholder + const PLACEHOLDER_LEN: usize = 8; + let mut buf = [0u8; PLACEHOLDER_LEN]; + + let head_len = { + let mut head_dst = &mut buf[..]; + encode_int(huff_len, 7, 0x80, &mut head_dst); + PLACEHOLDER_LEN - head_dst.remaining_mut() + }; + + // This is just done to reserve space in the destination + dst.put_slice(&buf[1..head_len]); + + // Shift the header forward + for i in 0..huff_len { + let src_i = idx + 1 + (huff_len - (i + 1)); + let dst_i = idx + head_len + (huff_len - (i + 1)); + dst[dst_i] = dst[src_i]; + } + + // Copy in the head + for i in 0..head_len { + dst[idx + i] = buf[i]; + } + } + } else { + // Write an empty string + dst.put_u8(0); + } +} + +/// Encode an integer into the given destination buffer +fn encode_int<B: BufMut>( + mut value: usize, // The integer to encode + prefix_bits: usize, // The number of bits in the prefix + first_byte: u8, // The base upon which to start encoding the int + dst: &mut B, +) { + if encode_int_one_byte(value, prefix_bits) { + dst.put_u8(first_byte | value as u8); + return; + } + + let low = (1 << prefix_bits) - 1; + + value -= low; + + dst.put_u8(first_byte | low as u8); + + while value >= 128 { + dst.put_u8(0b1000_0000 | value as u8); + + value >>= 7; + } + + dst.put_u8(value as u8); +} + +/// Returns true if the in the int can be fully encoded in the first byte. +fn encode_int_one_byte(value: usize, prefix_bits: usize) -> bool { + value < (1 << prefix_bits) - 1 +} + +fn position(buf: &BytesMut) -> usize { + buf.len() +} + +#[cfg(test)] +mod test { + use super::*; + use crate::hpack::Header; + use http::*; + + #[test] + fn test_encode_method_get() { + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![method("GET")]); + assert_eq!(*res, [0x80 | 2]); + assert_eq!(encoder.table.len(), 0); + } + + #[test] + fn test_encode_method_post() { + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![method("POST")]); + assert_eq!(*res, [0x80 | 3]); + assert_eq!(encoder.table.len(), 0); + } + + #[test] + fn test_encode_method_patch() { + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![method("PATCH")]); + + assert_eq!(res[0], 0b01000000 | 2); // Incremental indexing w/ name pulled from table + assert_eq!(res[1], 0x80 | 5); // header value w/ huffman coding + + assert_eq!("PATCH", huff_decode(&res[2..7])); + assert_eq!(encoder.table.len(), 1); + + let res = encode(&mut encoder, vec![method("PATCH")]); + + assert_eq!(1 << 7 | 62, res[0]); + assert_eq!(1, res.len()); + } + + #[test] + fn test_encode_indexed_name_literal_value() { + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![header("content-language", "foo")]); + + assert_eq!(res[0], 0b01000000 | 27); // Indexed name + assert_eq!(res[1], 0x80 | 2); // header value w/ huffman coding + + assert_eq!("foo", huff_decode(&res[2..4])); + + // Same name, new value should still use incremental + let res = encode(&mut encoder, vec![header("content-language", "bar")]); + assert_eq!(res[0], 0b01000000 | 27); // Indexed name + assert_eq!(res[1], 0x80 | 3); // header value w/ huffman coding + assert_eq!("bar", huff_decode(&res[2..5])); + } + + #[test] + fn test_repeated_headers_are_indexed() { + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![header("foo", "hello")]); + + assert_eq!(&[0b01000000, 0x80 | 2], &res[0..2]); + assert_eq!("foo", huff_decode(&res[2..4])); + assert_eq!(0x80 | 4, res[4]); + assert_eq!("hello", huff_decode(&res[5..])); + assert_eq!(9, res.len()); + + assert_eq!(1, encoder.table.len()); + + let res = encode(&mut encoder, vec![header("foo", "hello")]); + assert_eq!([0x80 | 62], *res); + + assert_eq!(encoder.table.len(), 1); + } + + #[test] + fn test_evicting_headers() { + let mut encoder = Encoder::default(); + + // Fill the table + for i in 0..64 { + let key = format!("x-hello-world-{:02}", i); + let res = encode(&mut encoder, vec![header(&key, &key)]); + + assert_eq!(&[0b01000000, 0x80 | 12], &res[0..2]); + assert_eq!(key, huff_decode(&res[2..14])); + assert_eq!(0x80 | 12, res[14]); + assert_eq!(key, huff_decode(&res[15..])); + assert_eq!(27, res.len()); + + // Make sure the header can be found... + let res = encode(&mut encoder, vec![header(&key, &key)]); + + // Only check that it is found + assert_eq!(0x80, res[0] & 0x80); + } + + assert_eq!(4096, encoder.table.size()); + assert_eq!(64, encoder.table.len()); + + // Find existing headers + for i in 0..64 { + let key = format!("x-hello-world-{:02}", i); + let res = encode(&mut encoder, vec![header(&key, &key)]); + assert_eq!(0x80, res[0] & 0x80); + } + + // Insert a new header + let key = "x-hello-world-64"; + let res = encode(&mut encoder, vec![header(key, key)]); + + assert_eq!(&[0b01000000, 0x80 | 12], &res[0..2]); + assert_eq!(key, huff_decode(&res[2..14])); + assert_eq!(0x80 | 12, res[14]); + assert_eq!(key, huff_decode(&res[15..])); + assert_eq!(27, res.len()); + + assert_eq!(64, encoder.table.len()); + + // Now try encoding entries that should exist in the table + for i in 1..65 { + let key = format!("x-hello-world-{:02}", i); + let res = encode(&mut encoder, vec![header(&key, &key)]); + assert_eq!(0x80 | (61 + (65 - i)), res[0]); + } + } + + #[test] + fn test_large_headers_are_not_indexed() { + let mut encoder = Encoder::new(128, 0); + let key = "hello-world-hello-world-HELLO-zzz"; + + let res = encode(&mut encoder, vec![header(key, key)]); + + assert_eq!(&[0, 0x80 | 25], &res[..2]); + + assert_eq!(0, encoder.table.len()); + assert_eq!(0, encoder.table.size()); + } + + #[test] + fn test_sensitive_headers_are_never_indexed() { + use http::header::HeaderValue; + + let name = "my-password".parse().unwrap(); + let mut value = HeaderValue::from_bytes(b"12345").unwrap(); + value.set_sensitive(true); + + let header = Header::Field { + name: Some(name), + value, + }; + + // Now, try to encode the sensitive header + + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![header]); + + assert_eq!(&[0b10000, 0x80 | 8], &res[..2]); + assert_eq!("my-password", huff_decode(&res[2..10])); + assert_eq!(0x80 | 4, res[10]); + assert_eq!("12345", huff_decode(&res[11..])); + + // Now, try to encode a sensitive header w/ a name in the static table + let name = "authorization".parse().unwrap(); + let mut value = HeaderValue::from_bytes(b"12345").unwrap(); + value.set_sensitive(true); + + let header = Header::Field { + name: Some(name), + value, + }; + + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![header]); + + assert_eq!(&[0b11111, 8], &res[..2]); + assert_eq!(0x80 | 4, res[2]); + assert_eq!("12345", huff_decode(&res[3..])); + + // Using the name component of a previously indexed header (without + // sensitive flag set) + + let _ = encode( + &mut encoder, + vec![self::header("my-password", "not-so-secret")], + ); + + let name = "my-password".parse().unwrap(); + let mut value = HeaderValue::from_bytes(b"12345").unwrap(); + value.set_sensitive(true); + + let header = Header::Field { + name: Some(name), + value, + }; + let res = encode(&mut encoder, vec![header]); + + assert_eq!(&[0b11111, 47], &res[..2]); + assert_eq!(0x80 | 4, res[2]); + assert_eq!("12345", huff_decode(&res[3..])); + } + + #[test] + fn test_content_length_value_not_indexed() { + let mut encoder = Encoder::default(); + let res = encode(&mut encoder, vec![header("content-length", "1234")]); + + assert_eq!(&[15, 13, 0x80 | 3], &res[0..3]); + assert_eq!("1234", huff_decode(&res[3..])); + assert_eq!(6, res.len()); + } + + #[test] + fn test_encoding_headers_with_same_name() { + let mut encoder = Encoder::default(); + let name = "hello"; + + // Encode first one + let _ = encode(&mut encoder, vec![header(name, "one")]); + + // Encode second one + let res = encode(&mut encoder, vec![header(name, "two")]); + assert_eq!(&[0x40 | 62, 0x80 | 3], &res[0..2]); + assert_eq!("two", huff_decode(&res[2..])); + assert_eq!(5, res.len()); + + // Encode the first one again + let res = encode(&mut encoder, vec![header(name, "one")]); + assert_eq!(&[0x80 | 63], &res[..]); + + // Now the second one + let res = encode(&mut encoder, vec![header(name, "two")]); + assert_eq!(&[0x80 | 62], &res[..]); + } + + #[test] + fn test_evicting_headers_when_multiple_of_same_name_are_in_table() { + // The encoder only has space for 2 headers + let mut encoder = Encoder::new(76, 0); + + let _ = encode(&mut encoder, vec![header("foo", "bar")]); + assert_eq!(1, encoder.table.len()); + + let _ = encode(&mut encoder, vec![header("bar", "foo")]); + assert_eq!(2, encoder.table.len()); + + // This will evict the first header, while still referencing the header + // name + let res = encode(&mut encoder, vec![header("foo", "baz")]); + assert_eq!(&[0x40 | 63, 0, 0x80 | 3], &res[..3]); + assert_eq!(2, encoder.table.len()); + + // Try adding the same header again + let res = encode(&mut encoder, vec![header("foo", "baz")]); + assert_eq!(&[0x80 | 62], &res[..]); + assert_eq!(2, encoder.table.len()); + } + + #[test] + fn test_max_size_zero() { + // Static table only + let mut encoder = Encoder::new(0, 0); + let res = encode(&mut encoder, vec![method("GET")]); + assert_eq!(*res, [0x80 | 2]); + assert_eq!(encoder.table.len(), 0); + + let res = encode(&mut encoder, vec![header("foo", "bar")]); + assert_eq!(&[0, 0x80 | 2], &res[..2]); + assert_eq!("foo", huff_decode(&res[2..4])); + assert_eq!(0x80 | 3, res[4]); + assert_eq!("bar", huff_decode(&res[5..8])); + assert_eq!(0, encoder.table.len()); + + // Encode a custom value + let res = encode(&mut encoder, vec![header("transfer-encoding", "chunked")]); + assert_eq!(&[15, 42, 0x80 | 6], &res[..3]); + assert_eq!("chunked", huff_decode(&res[3..])); + } + + #[test] + fn test_update_max_size_combos() { + let mut encoder = Encoder::default(); + assert!(encoder.size_update.is_none()); + assert_eq!(4096, encoder.table.max_size()); + + encoder.update_max_size(4096); // Default size + assert!(encoder.size_update.is_none()); + + encoder.update_max_size(0); + assert_eq!(Some(SizeUpdate::One(0)), encoder.size_update); + + encoder.update_max_size(100); + assert_eq!(Some(SizeUpdate::Two(0, 100)), encoder.size_update); + + let mut encoder = Encoder::default(); + encoder.update_max_size(8000); + assert_eq!(Some(SizeUpdate::One(8000)), encoder.size_update); + + encoder.update_max_size(100); + assert_eq!(Some(SizeUpdate::One(100)), encoder.size_update); + + encoder.update_max_size(8000); + assert_eq!(Some(SizeUpdate::Two(100, 8000)), encoder.size_update); + + encoder.update_max_size(4000); + assert_eq!(Some(SizeUpdate::Two(100, 4000)), encoder.size_update); + + encoder.update_max_size(50); + assert_eq!(Some(SizeUpdate::One(50)), encoder.size_update); + } + + #[test] + fn test_resizing_table() { + let mut encoder = Encoder::default(); + + // Add a header + let _ = encode(&mut encoder, vec![header("foo", "bar")]); + + encoder.update_max_size(1); + assert_eq!(1, encoder.table.len()); + + let res = encode(&mut encoder, vec![method("GET")]); + assert_eq!(&[32 | 1, 0x80 | 2], &res[..]); + assert_eq!(0, encoder.table.len()); + + let res = encode(&mut encoder, vec![header("foo", "bar")]); + assert_eq!(0, res[0]); + + encoder.update_max_size(100); + let res = encode(&mut encoder, vec![header("foo", "bar")]); + assert_eq!(&[32 | 31, 69, 64], &res[..3]); + + encoder.update_max_size(0); + let res = encode(&mut encoder, vec![header("foo", "bar")]); + assert_eq!(&[32, 0], &res[..2]); + } + + #[test] + fn test_decreasing_table_size_without_eviction() { + let mut encoder = Encoder::default(); + + // Add a header + let _ = encode(&mut encoder, vec![header("foo", "bar")]); + + encoder.update_max_size(100); + assert_eq!(1, encoder.table.len()); + + let res = encode(&mut encoder, vec![header("foo", "bar")]); + assert_eq!(&[32 | 31, 69, 0x80 | 62], &res[..]); + } + + #[test] + fn test_nameless_header() { + let mut encoder = Encoder::default(); + + let res = encode( + &mut encoder, + vec![ + Header::Field { + name: Some("hello".parse().unwrap()), + value: HeaderValue::from_bytes(b"world").unwrap(), + }, + Header::Field { + name: None, + value: HeaderValue::from_bytes(b"zomg").unwrap(), + }, + ], + ); + + assert_eq!(&[0x40, 0x80 | 4], &res[0..2]); + assert_eq!("hello", huff_decode(&res[2..6])); + assert_eq!(0x80 | 4, res[6]); + assert_eq!("world", huff_decode(&res[7..11])); + + // Next is not indexed + assert_eq!(&[15, 47, 0x80 | 3], &res[11..14]); + assert_eq!("zomg", huff_decode(&res[14..])); + } + + #[test] + fn test_large_size_update() { + let mut encoder = Encoder::default(); + + encoder.update_max_size(1912930560); + assert_eq!(Some(SizeUpdate::One(1912930560)), encoder.size_update); + + let mut dst = BytesMut::with_capacity(6); + encoder.encode_size_updates(&mut dst); + assert_eq!([63, 225, 129, 148, 144, 7], &dst[..]); + } + + #[test] + #[ignore] + fn test_evicted_overflow() { + // Not sure what the best way to do this is. + } + + fn encode(e: &mut Encoder, hdrs: Vec<Header<Option<HeaderName>>>) -> BytesMut { + let mut dst = BytesMut::with_capacity(1024); + e.encode(&mut hdrs.into_iter(), &mut dst); + dst + } + + fn method(s: &str) -> Header<Option<HeaderName>> { + Header::Method(Method::from_bytes(s.as_bytes()).unwrap()) + } + + fn header(name: &str, val: &str) -> Header<Option<HeaderName>> { + let name = HeaderName::from_bytes(name.as_bytes()).unwrap(); + let value = HeaderValue::from_bytes(val.as_bytes()).unwrap(); + + Header::Field { + name: Some(name), + value, + } + } + + fn huff_decode(src: &[u8]) -> BytesMut { + let mut buf = BytesMut::new(); + huffman::decode(src, &mut buf).unwrap() + } +} |