bt_obex/header/
obex_string.rs

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1// Copyright 2023 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5use crate::error::PacketError;
6
7/// Represents the String type that is sent/received in an OBEX packet.
8/// Encoded as null-terminated UTF-16 text.
9/// Defined in OBEX 1.5. Section 2.1.
10#[derive(Clone, Debug, PartialEq)]
11pub struct ObexString(pub String);
12
13impl ObexString {
14    pub fn len(&self) -> usize {
15        self.to_be_bytes().len()
16    }
17
18    pub fn to_be_bytes(&self) -> Vec<u8> {
19        let mut encoded_buf: Vec<u16> = self.0.encode_utf16().collect();
20        encoded_buf.push(0); // Add the null terminator
21        encoded_buf.into_iter().map(|v| v.to_be_bytes()).flatten().collect()
22    }
23}
24
25impl From<String> for ObexString {
26    fn from(src: String) -> ObexString {
27        ObexString(src)
28    }
29}
30
31impl From<&str> for ObexString {
32    fn from(src: &str) -> ObexString {
33        ObexString(src.to_string())
34    }
35}
36
37impl TryFrom<&[u8]> for ObexString {
38    type Error = PacketError;
39
40    fn try_from(src: &[u8]) -> Result<Self, Self::Error> {
41        if src.len() == 0 {
42            return Ok(Self(String::new()));
43        }
44
45        let unicode_array = src
46            .chunks_exact(2)
47            .into_iter()
48            .map(|a| u16::from_be_bytes([a[0], a[1]]))
49            .collect::<Vec<u16>>();
50        let mut text = String::from_utf16(&unicode_array).map_err(PacketError::external)?;
51        // OBEX Strings are represented as null terminated Unicode text. See OBEX 1.5 Section 2.1.
52        if !text.ends_with('\0') {
53            return Err(PacketError::data("text missing null terminator"));
54        }
55
56        let _ = text.pop();
57        Ok(Self(text))
58    }
59}
60
61impl ToString for ObexString {
62    fn to_string(&self) -> String {
63        self.0.clone()
64    }
65}
66
67#[cfg(test)]
68mod tests {
69    use super::*;
70
71    use assert_matches::assert_matches;
72
73    fn expect_strings_equal(s1: ObexString, s2: String) {
74        assert_eq!(s1.0, s2);
75    }
76
77    #[fuchsia::test]
78    fn obex_string_from_bytes() {
79        // Empty buf
80        let converted = ObexString::try_from(&[][..]).expect("can convert to String");
81        expect_strings_equal(converted, "".to_string());
82
83        // Just a null terminator.
84        let buf = [0x00, 0x00];
85        let converted = ObexString::try_from(&buf[..]).expect("can convert to String");
86        expect_strings_equal(converted, "".to_string());
87
88        // "hello"
89        let buf = [0x00, 0x68, 0x00, 0x65, 0x00, 0x6c, 0x00, 0x6c, 0x00, 0x6f, 0x00, 0x00];
90        let converted = ObexString::try_from(&buf[..]).expect("can convert to String");
91        expect_strings_equal(converted, "hello".to_string());
92
93        // "bob" with two null terminators - only last is removed.
94        let buf = [0x00, 0x62, 0x00, 0x6f, 0x00, 0x62, 0x00, 0x00, 0x00, 0x00];
95        let converted = ObexString::try_from(&buf[..]).expect("can convert to String");
96        expect_strings_equal(converted, "bob\0".to_string());
97    }
98
99    #[fuchsia::test]
100    fn obex_string_missing_terminator_is_error() {
101        // `foo.txt` with no null terminator.
102        let buf =
103            [0x00, 0x66, 0x00, 0x6f, 0x00, 0x6f, 0x00, 0x2e, 0x00, 0x74, 0x00, 0x78, 0x00, 0x74];
104        let converted = ObexString::try_from(&buf[..]);
105        assert_matches!(converted, Err(PacketError::Data(_)));
106    }
107
108    #[fuchsia::test]
109    fn obex_string_invalid_utf16_is_error() {
110        // Invalid utf-16 bytes.
111        let buf =
112            [0xd8, 0x34, 0xdd, 0x1e, 0x00, 0x6d, 0x00, 0x75, 0xd8, 0x00, 0x00, 0x69, 0x00, 0x63];
113        let converted = ObexString::try_from(&buf[..]);
114        assert_matches!(converted, Err(PacketError::Other(_)));
115    }
116}
bt_obex/header/obex_string.rs

bt_obex/header/
obex_string.rs
