flv: Implement Script Data parsing.
Yes, FLVs support embedded ActionScript data. Who knew?!
This commit is contained in:
David Wendt
kmeisthax
parent
65583a7173
commit
f115326f3e
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@ -1,4 +1,5 @@
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mod header;
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mod script;
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mod sound;
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mod tag;
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mod video;
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@ -32,22 +32,57 @@ impl<'a> FlvReader<'a> {
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Some(&self.source[start..end])
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}
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/// Read a certain number of bytes from the buffer without advancing the
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/// buffer position.
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pub fn peek(&mut self, count: usize) -> Option<&'a [u8]> {
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let pos = self.position;
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let ret = self.read(count);
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self.position = pos;
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ret
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}
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pub fn read_u8(&mut self) -> Option<u8> {
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Some(self.read(1)?[0])
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}
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pub fn read_u16(&mut self) -> Option<u16> {
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Some(u16::from_be_bytes(
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self.read(2)?.try_into().expect("two bytes"),
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))
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}
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pub fn read_i16(&mut self) -> Option<i16> {
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Some(i16::from_be_bytes(
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self.read(2)?.try_into().expect("two bytes"),
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))
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}
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pub fn read_u24(&mut self) -> Option<u32> {
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let bytes = self.read(3)?;
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Some(u32::from_be_bytes([0, bytes[0], bytes[1], bytes[2]]))
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}
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pub fn peek_u24(&mut self) -> Option<u32> {
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let bytes = self.peek(3)?;
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Some(u32::from_be_bytes([0, bytes[0], bytes[1], bytes[2]]))
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}
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pub fn read_u32(&mut self) -> Option<u32> {
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Some(u32::from_be_bytes(
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self.read(4)?.try_into().expect("four bytes"),
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))
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}
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pub fn read_f64(&mut self) -> Option<f64> {
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Some(f64::from_be_bytes(
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self.read(8)?.try_into().expect("eight bytes"),
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))
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}
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pub fn position(&self) -> usize {
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self.position
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}
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@ -0,0 +1,391 @@
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use crate::reader::FlvReader;
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fn parse_string<'a>(reader: &mut FlvReader<'a>, is_long_string: bool) -> Option<&'a [u8]> {
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let length = if is_long_string {
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reader.read_u32()?
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} else {
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reader.read_u16()? as u32
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};
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reader.read(length as usize)
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}
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#[repr(u8)]
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#[derive(PartialEq, Debug)]
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pub enum Value<'a> {
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Number(f64) = 0,
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Boolean(bool) = 1,
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String(&'a [u8]) = 2,
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Object(Vec<Variable<'a>>) = 3,
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MovieClip(&'a [u8]) = 4, // Is a string that defines a MovieClip path
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Null = 5,
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Undefined = 6,
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Reference(u16) = 7,
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EcmaArray(Vec<Variable<'a>>) = 8,
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StrictArray(Vec<Variable<'a>>) = 10,
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Date {
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/// The number of milliseconds since January 1st, 1970.
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unix_time: f64,
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/// Local time offset in minutes from UTC.
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/// Time zones west of Greenwich, UK are negative.
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local_offset: i16,
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} = 11,
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LongString(&'a [u8]) = 12,
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}
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impl<'a> Value<'a> {
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/// Parse a script value.
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///
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/// Strings are yielded as byte arrays, as there is no guidance in the FLV
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/// specification as to how they are to be decoded.
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///
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/// data_size is the size of the entire script data structure.
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pub fn parse(reader: &mut FlvReader<'a>) -> Option<Self> {
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let value_type = reader.read_u8()?;
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match value_type {
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0 => Some(Self::Number(reader.read_f64()?)),
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1 => Some(Self::Boolean(reader.read_u8()? != 0)),
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2 => Some(Self::String(parse_string(reader, false)?)),
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3 => {
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let mut variables = vec![];
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loop {
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let terminator = reader.peek_u24()?;
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if terminator == 9 {
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reader.read_u24()?;
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return Some(Self::Object(variables));
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}
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variables.push(Variable::parse(reader)?);
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}
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}
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4 => Some(Self::MovieClip(parse_string(reader, false)?)),
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5 => Some(Self::Null),
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6 => Some(Self::Undefined),
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7 => Some(Self::Reference(reader.read_u16()?)),
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8 => {
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let length_hint = reader.read_u32()?;
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let mut variables = Vec::with_capacity(length_hint as usize);
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loop {
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let terminator = reader.peek_u24()?;
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if terminator == 9 {
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reader.read_u24()?;
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return Some(Self::EcmaArray(variables));
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}
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variables.push(Variable::parse(reader)?);
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}
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}
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10 => {
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let length = reader.read_u32()?;
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let mut variables = Vec::with_capacity(length as usize);
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for _ in 0..length {
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variables.push(Variable::parse(reader)?);
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}
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Some(Self::StrictArray(variables))
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}
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11 => Some(Self::Date {
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unix_time: reader.read_f64()?,
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local_offset: reader.read_i16()?,
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}),
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12 => Some(Self::LongString(parse_string(reader, true)?)),
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_ => None,
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}
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}
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}
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/// An individual object in a ScriptData tag.
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///
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/// This corresponds to both the `SCRIPTDATAOBJECT` and `SCRIPTDATAVARIABLE`
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/// structures as defined in the FLV specification. These structures are
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/// otherwise identical.
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#[derive(PartialEq, Debug)]
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pub struct Variable<'a> {
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name: &'a [u8],
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data: Value<'a>,
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}
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impl<'a> Variable<'a> {
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pub fn parse(reader: &mut FlvReader<'a>) -> Option<Self> {
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Some(Self {
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name: parse_string(reader, false)?,
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data: Value::parse(reader)?,
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})
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}
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}
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#[derive(PartialEq, Debug)]
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pub struct ScriptData<'a>(Vec<Variable<'a>>);
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impl<'a> ScriptData<'a> {
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/// Parse a script data structure.
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///
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/// No data size parameter is accepted; we parse until we reach an object
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/// terminator, reach invalid data, or we run out of bytes in the reader.
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pub fn parse(reader: &mut FlvReader<'a>) -> Option<Self> {
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let mut vars = vec![];
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loop {
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let is_return = reader.peek_u24()?;
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if is_return == 9 {
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reader.read_u24()?;
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return Some(Self(vars));
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}
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vars.push(Variable::parse(reader)?);
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::reader::FlvReader;
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use crate::script::{parse_string, ScriptData, Value, Variable};
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#[test]
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fn read_string() {
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let data = [0x00, 0x03, 0x01, 0x02, 0x03];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(parse_string(&mut reader, false), Some(&data[2..]));
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}
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#[test]
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fn read_string_long() {
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let data = [0x00, 0x00, 0x00, 0x03, 0x01, 0x02, 0x03];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(parse_string(&mut reader, true), Some(&data[4..]));
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}
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#[test]
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fn read_value_number() {
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let data = [0x00, 0x40, 0x28, 0x99, 0x99, 0x99, 0x99, 0x99, 0x9a];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(Value::parse(&mut reader), Some(Value::Number(12.3)));
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}
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#[test]
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fn read_value_boolean() {
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let data = [0x01, 0x01];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(Value::parse(&mut reader), Some(Value::Boolean(true)));
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}
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#[test]
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fn read_value_string() {
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let data = [0x02, 0x00, 0x03, 0x01, 0x02, 0x03];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::String(&[0x01, 0x02, 0x03]))
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);
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}
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#[test]
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fn read_value_movieclip() {
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let data = [0x04, 0x00, 0x03, 0x01, 0x02, 0x03];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::MovieClip(&[0x01, 0x02, 0x03]))
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);
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}
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#[test]
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fn read_value_longstring() {
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let data = [0x0C, 0x00, 0x00, 0x00, 0x03, 0x01, 0x02, 0x03];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::LongString(&[0x01, 0x02, 0x03]))
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);
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}
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#[test]
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fn read_value_null() {
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let data = [0x05];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(Value::parse(&mut reader), Some(Value::Null));
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}
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#[test]
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fn read_value_undefined() {
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let data = [0x06];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(Value::parse(&mut reader), Some(Value::Undefined));
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}
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#[test]
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fn read_value_reference() {
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let data = [0x07, 0x24, 0x38];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(Value::parse(&mut reader), Some(Value::Reference(0x2438)));
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}
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#[test]
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fn read_value_date() {
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let data = [
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0x0B, 0x40, 0x28, 0x99, 0x99, 0x99, 0x99, 0x99, 0x9a, 0xFF, 0xFE,
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];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::Date {
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unix_time: 12.3,
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local_offset: -2
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})
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);
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}
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#[test]
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fn read_value_object() {
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let data = [
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0x03, 0x00, 0x03, 0x01, 0x02, 0x03, 0x06, 0x00, 0x03, 0x01, 0x02, 0x03, 0x05, 0x00,
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0x00, 0x09,
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];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::Object(vec![
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Undefined
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},
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Null
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}
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]))
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);
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}
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#[test]
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fn read_value_ecmaarray() {
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let data = [
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0x08, 0x00, 0x00, 0x00, 0x02, 0x00, 0x03, 0x01, 0x02, 0x03, 0x06, 0x00, 0x03, 0x01,
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0x02, 0x03, 0x05, 0x00, 0x00, 0x09,
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];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::EcmaArray(vec![
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Undefined
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},
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Null
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}
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]))
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);
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}
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#[test]
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fn read_value_ecmaarray_longlen() {
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let data = [
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0x08, 0x00, 0x00, 0x0F, 0x02, 0x00, 0x03, 0x01, 0x02, 0x03, 0x06, 0x00, 0x03, 0x01,
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0x02, 0x03, 0x05, 0x00, 0x00, 0x09,
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];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::EcmaArray(vec![
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Undefined
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},
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Null
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}
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]))
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);
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}
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#[test]
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fn read_value_ecmaarray_shortlen() {
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let data = [
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0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x01, 0x02, 0x03, 0x06, 0x00, 0x03, 0x01,
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0x02, 0x03, 0x05, 0x00, 0x00, 0x09,
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];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::EcmaArray(vec![
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Undefined
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},
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Null
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}
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]))
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);
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}
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#[test]
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fn read_value_strictarray() {
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let data = [
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0x0A, 0x00, 0x00, 0x00, 0x02, 0x00, 0x03, 0x01, 0x02, 0x03, 0x06, 0x00, 0x03, 0x01,
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0x02, 0x03, 0x05,
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];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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Value::parse(&mut reader),
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Some(Value::StrictArray(vec![
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Undefined
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},
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Null
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}
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]))
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);
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}
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#[test]
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fn read_scriptdata() {
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let data = [
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0x00, 0x03, 0x01, 0x02, 0x03, 0x06, 0x00, 0x03, 0x01, 0x02, 0x03, 0x05, 0x00, 0x00,
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0x09,
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];
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let mut reader = FlvReader::from_source(&data);
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assert_eq!(
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ScriptData::parse(&mut reader),
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Some(ScriptData(vec![
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Undefined
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},
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Variable {
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name: &[0x01, 0x02, 0x03],
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data: Value::Null
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}
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]))
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);
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}
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}
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@ -1,4 +1,5 @@
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use crate::reader::FlvReader;
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use crate::script::ScriptData;
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use crate::sound::AudioData;
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use crate::video::VideoData;
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@ -6,7 +7,7 @@ use crate::video::VideoData;
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pub enum TagData<'a> {
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Audio(AudioData<'a>) = 8,
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Video(VideoData<'a>) = 9,
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Script = 18,
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Script(ScriptData<'a>) = 18,
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}
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pub struct Tag<'a> {
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@ -40,6 +41,11 @@ impl<'a> Tag<'a> {
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stream_id,
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data: TagData::Video(VideoData::parse(reader, data_size)?),
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}),
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18 => Some(Tag {
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timestamp,
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stream_id,
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data: TagData::Script(ScriptData::parse(reader)?),
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}),
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_ => None,
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}
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}
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