1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144

use std::mem;
use std::str;

use error::{Error, Result};
use serde_am::{Deserialize};

pub struct Deserializer<'a> {
    pub bytes: &'a [u8],
}

/// Deserializes a struct from a byte buffer,
/// and returns an [`Error`](enum.error.html)
/// when the bytes cannot be deserialized 
/// to the given type. 
/// 
/// # Example
/// ```
/// # extern crate airmash_protocol;
/// # use airmash_protocol::{from_bytes, ClientPacket};
/// # fn main() {
/// // Bytes representing an Ack packet
/// let bytes = [ 5 ];
/// 
/// // Decode the packet
/// let ack = from_bytes::<ClientPacket>(&bytes).unwrap();
/// 
/// // Do stuff with packet here...
/// match ack {
///     Ack => return,
///     _ => panic!("This wasn't an ack packet!")
/// }
/// # }
/// ```
/// 
/// # Error Example
/// ```
/// # extern crate airmash_protocol;
/// # use airmash_protocol::{from_bytes, ServerPacket, Error};
/// # use airmash_protocol::server::ChatPublic;
/// # fn main() { // Need for extern crate to work
/// // An incomplete ChatPublic packet.
/// // In this case, the packet is too short.
/// let bytes = [ 70 ];
/// 
/// // Try to decode the packet
/// let result = from_bytes::<ChatPublic>(&bytes);
/// 
/// // Do something with the error here...
/// match result {
///     Ok(_) => panic!("Unexpected success!"),
///     Err(err) => return
/// }
/// # }
/// ```
pub fn from_bytes<'a, T>(b: &'a [u8]) -> Result<T>
where
    T: Deserialize<'a>,
{
    let mut deserializer = Deserializer::from_bytes(b);
    let t = T::deserialize(&mut deserializer)?;

    if deserializer.bytes.is_empty() {
        Ok(t)
    } else {
        Err(Error::TrailingBytes)
    }
}

impl<'a> Deserializer<'a> {
    pub fn from_bytes(bytes: &'a [u8]) -> Self {
        return Self { bytes };
    }
}

impl<'de> Deserializer<'de> {
    pub fn deserialize_i8(&mut self) -> Result<i8> {
        Ok(self.deserialize_u8()? as i8)
    }
    pub fn deserialize_i16(&mut self) -> Result<i16> {
        Ok(self.deserialize_u16()? as i16)
    }
    pub fn deserialize_i32(&mut self) -> Result<i32> {
        Ok(self.deserialize_u32()? as i32)
    }
    pub fn deserialize_i64(&mut self) -> Result<i64> {
        Ok(self.deserialize_u64()? as i64)
    }

    pub fn deserialize_u8(&mut self) -> Result<u8> {
        if self.bytes.len() == 0 {
            return Err(Error::Eof);
        }

        let b = self.bytes[0];
        self.bytes = &self.bytes[1..];
        Ok(b)
    }
    pub fn deserialize_u16(&mut self) -> Result<u16> {
        let lo = self.deserialize_u8()?;
        let hi = self.deserialize_u8()?;

        Ok(((hi as u16) << 8) | (lo as u16))
    }
    pub fn deserialize_u32(&mut self) -> Result<u32> {
        let lo = self.deserialize_u16()?;
        let hi = self.deserialize_u16()?;

        Ok(((hi as u32) << 16) | (lo as u32))
    }
    pub fn deserialize_u64(&mut self) -> Result<u64> {
        let lo = self.deserialize_u32()?;
        let hi = self.deserialize_u32()?;

        Ok(((hi as u64) << 32) | (lo as u64))
    }

    pub fn deserialize_f32(&mut self) -> Result<f32> {
        Ok(unsafe { mem::transmute::<u32, f32>(self.deserialize_u32()?) })
    }
    pub fn deserialize_f64(&mut self) -> Result<f64> {
        Ok(unsafe { mem::transmute::<u64, f64>(self.deserialize_u64()?) })
    }

    pub fn deserialize_unit(&mut self) -> Result<()> {
        Ok(())
    }
    pub fn deserialize_bytes(&mut self, len: usize) -> Result<&'de [u8]> {
        if self.bytes.len() < len {
            return Err(Error::Eof);
        }

        let slice = &self.bytes[0..len];
        self.bytes = &self.bytes[len..];
        Ok(slice)
    }
    pub fn deserialize_str(&mut self, len: usize) -> Result<&'de str> {
        let bytes = self.deserialize_bytes(len)?;

        match str::from_utf8(bytes) {
            Ok(val) => Ok(val),
            Err(e) => Err(Error::Utf8Error(e)),
        }
    }
}