83 lines
3.0 KiB
Rust
83 lines
3.0 KiB
Rust
// This file is part of Moonfire NVR, a security camera digital video recorder.
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// Copyright (C) 2016 Scott Lamb <slamb@slamb.org>
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// In addition, as a special exception, the copyright holders give
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// permission to link the code of portions of this program with the
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// OpenSSL library under certain conditions as described in each
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// individual source file, and distribute linked combinations including
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// the two.
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//
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// You must obey the GNU General Public License in all respects for all
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// of the code used other than OpenSSL. If you modify file(s) with this
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// exception, you may extend this exception to your version of the
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// file(s), but you are not obligated to do so. If you do not wish to do
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// so, delete this exception statement from your version. If you delete
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// this exception statement from all source files in the program, then
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// also delete it here.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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/// Returns a hex-encoded version of the input.
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pub fn hex(raw: &[u8]) -> String {
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const HEX_CHARS: [u8; 16] = [b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
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b'8', b'9', b'a', b'b', b'c', b'd', b'e', b'f'];
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let mut hex = Vec::with_capacity(2 * raw.len());
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for b in raw {
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hex.push(HEX_CHARS[((b & 0xf0) >> 4) as usize]);
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hex.push(HEX_CHARS[( b & 0x0f ) as usize]);
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}
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unsafe { String::from_utf8_unchecked(hex) }
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}
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/// Returns [0, 16) or error.
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fn dehex_byte(hex_byte: u8) -> Result<u8, ()> {
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match hex_byte {
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b'0' ... b'9' => Ok(hex_byte - b'0'),
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b'a' ... b'f' => Ok(hex_byte - b'a' + 10),
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_ => Err(()),
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}
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}
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/// Returns a 20-byte raw form of the given hex string.
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/// (This is the size of a SHA1 hash, the only current use of this function.)
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pub fn dehex(hexed: &[u8]) -> Result<[u8; 20], ()> {
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if hexed.len() != 40 {
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return Err(());
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}
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let mut out = [0; 20];
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for i in 0..20 {
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out[i] = (dehex_byte(hexed[i<<1])? << 4) + dehex_byte(hexed[(i<<1) + 1])?;
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}
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Ok(out)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn round_trip() {
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let s = "de382684a471f178e4e3a163762711b0653bfd83";
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let dehexed = dehex(s.as_bytes()).unwrap();
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assert_eq!(&hex(&dehexed[..]), s);
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}
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#[test]
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fn dehex_errors() {
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dehex(b"").unwrap_err();
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dehex(b"de382684a471f178e4e3a163762711b0653bfd8g").unwrap_err();
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}
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}
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