code.octet-stream.net Git - hashgood/blob - src/verify.rs

   1 use super::{
   2     Algorithm, CandidateHash, CandidateHashes, Hash, MatchLevel, MessageLevel, Opt, Verification,
   3     VerificationSource,
   4 };
   5 use clipboard::ClipboardContext;
   6 use clipboard::ClipboardProvider;
   7 use regex::Regex;
   8 use std::fs::File;
   9 use std::io;
  10 use std::io::prelude::*;
  11 use std::io::BufReader;
  12 use std::path::PathBuf;
  13
  14 /// Calculate a list of candidate hashes based on the options specified.
  15 /// If no hash options have been specified returns None.
  16 /// It is assumed to be verified previously that at most one mode has been specified.
  17 pub fn get_candidate_hashes(opt: &Opt) -> Result<Option<CandidateHashes>, String> {
  18     if let Some(hash_string) = &opt.hash {
  19         return Ok(Some(get_by_parameter(hash_string)?));
  20     } else if opt.paste {
  21         return Ok(Some(get_from_clipboard()?));
  22     } else if let Some(hash_file) = &opt.hash_file {
  23         return Ok(Some(get_from_file(hash_file)?));
  24     }
  25     Ok(None)
  26 }
  27
  28 /// Generate a candidate hash from the provided command line parameter, or throw an error.
  29 fn get_by_parameter(param: &str) -> Result<CandidateHashes, String> {
  30     let bytes =
  31         hex::decode(&param).map_err(|_| "Provided hash is invalid or truncated hex".to_owned())?;
  32     let alg = Algorithm::from_len(bytes.len())?;
  33     let candidate = CandidateHash {
  34         filename: None,
  35         bytes,
  36     };
  37     Ok(CandidateHashes {
  38         alg,
  39         hashes: vec![candidate],
  40         source: VerificationSource::CommandArgument,
  41     })
  42 }
  43
  44 /// Generate a candidate hash from the system clipboard, or throw an error.
  45 fn get_from_clipboard() -> Result<CandidateHashes, String> {
  46     let mut ctx: ClipboardContext = match ClipboardProvider::new() {
  47         Ok(ctx) => ctx,
  48         Err(e) => return Err(format!("Error getting system clipboard: {}", e)),
  49     };
  50
  51     let possible_hash = match ctx.get_contents() {
  52         Ok(value) => value,
  53         Err(e) => format!("Error reading from clipboard: {}", e),
  54     };
  55
  56     let bytes = hex::decode(&possible_hash)
  57         .map_err(|_| "Clipboard contains invalid or truncated hex".to_owned())?;
  58     let alg = Algorithm::from_len(bytes.len())?;
  59     let candidate = CandidateHash {
  60         filename: None,
  61         bytes,
  62     };
  63     Ok(CandidateHashes {
  64         alg,
  65         hashes: vec![candidate],
  66         source: VerificationSource::Clipboard,
  67     })
  68 }
  69
  70 /// Generate a candidate hash from the digests file specified (could be "-" for STDIN), or throw an error.
  71 fn get_from_file(path: &PathBuf) -> Result<CandidateHashes, String> {
  72     // Get a reader for either standard input or the chosen path
  73     let reader: Box<dyn Read> = if path.to_str() == Some("-") {
  74         Box::new(std::io::stdin())
  75     } else {
  76         Box::new(File::open(path).map_err(|_| {
  77             format!(
  78                 "Unable to open check file at path '{}'",
  79                 path.to_string_lossy()
  80             )
  81         })?)
  82     };
  83
  84     // Read the first line, trimmed
  85     let mut reader = BufReader::new(reader);
  86     let mut line = String::new();
  87     reader
  88         .read_line(&mut line)
  89         .map_err(|_| "Error reading from check file".to_owned())?;
  90     let line = line.trim().to_owned();
  91
  92     // Does our first line look like a raw hash on its own? If so, use that
  93     if let Some(candidate) = read_raw_candidate_from_file(&line, &path) {
  94         return Ok(candidate);
  95     }
  96
  97     // Maybe it's a digests file
  98     // Reconstruct the full iterator by joining our already-read line with the others
  99     let full_lines = vec![Ok(line)].into_iter().chain(reader.lines());
 100
 101     // Does the entire file look like a coreutils-style digests file? (SHA1SUMS, etc.)
 102     if let Some(candidate) = read_coreutils_digests_from_file(full_lines, &path) {
 103         return Ok(candidate);
 104     }
 105
 106     // If neither of these techniques worked this is a fatal error
 107     // The user requested we use this input but we couldn't
 108     Err(format!(
 109         "Provided check file '{}' was neither a hash nor a valid digests file",
 110         path.to_string_lossy()
 111     ))
 112 }
 113
 114 fn read_raw_candidate_from_file(line: &str, path: &PathBuf) -> Option<CandidateHashes> {
 115     // It is a little sad to use a dynamic regex in an otherwise nice Rust program
 116     // These deserve to be replaced with a good old fashioned static parser
 117     // But let's be honest: the impact is negligible
 118     let re = Regex::new(r"^([[:xdigit:]]{32}|[[:xdigit:]]{40}|[[:xdigit:]]{64})$").unwrap();
 119     if re.is_match(line) {
 120         // These should both always succeed due to the matching
 121         let bytes = match hex::decode(line) {
 122             Ok(bytes) => bytes,
 123             _ => return None,
 124         };
 125         let alg = match Algorithm::from_len(bytes.len()) {
 126             Ok(alg) => alg,
 127             _ => return None,
 128         };
 129         return Some(CandidateHashes {
 130             alg,
 131             source: VerificationSource::RawFile(path.clone()),
 132             hashes: vec![CandidateHash {
 133                 bytes,
 134                 filename: None,
 135             }],
 136         });
 137     }
 138     None
 139 }
 140
 141 fn read_coreutils_digests_from_file<I>(lines: I, path: &PathBuf) -> Option<CandidateHashes>
 142 where
 143     I: Iterator<Item = io::Result<String>>,
 144 {
 145     let re = Regex::new(
 146         r"^(?P<hash>([[:xdigit:]]{32}|[[:xdigit:]]{40}|[[:xdigit:]]{64})) .(?P<filename>.+)$",
 147     )
 148     .unwrap();
 149
 150     let mut hashes = vec![];
 151     let mut alg: Option<Algorithm> = None;
 152     for l in lines {
 153         if let Ok(l) = l {
 154             let l = l.trim();
 155             // Allow (ignore) blank lines
 156             if l.is_empty() {
 157                 continue;
 158             }
 159             // If we can capture a valid line, use it
 160             if let Some(captures) = re.captures(&l) {
 161                 let hash = &captures["hash"];
 162                 let filename = &captures["filename"];
 163                 // Decode the hex and algorithm for this line
 164                 let line_bytes = match hex::decode(hash) {
 165                     Ok(bytes) => bytes,
 166                     _ => return None,
 167                 };
 168                 let line_alg = match Algorithm::from_len(line_bytes.len()) {
 169                     Ok(alg) => alg,
 170                     _ => return None,
 171                 };
 172                 if alg.is_some() && alg != Some(line_alg) {
 173                     // Different algorithms in the same digest file are not supported
 174                     return None;
 175                 } else {
 176                     // If we are the first line, we define the overall algorithm
 177                     alg = Some(line_alg);
 178                 }
 179                 // So far so good - create an entry for this line
 180                 hashes.push(CandidateHash {
 181                     bytes: line_bytes,
 182                     filename: Some(filename.to_owned()),
 183                 });
 184             } else {
 185                 // But if we have a line with content we cannot parse, this is an error
 186                 return None;
 187             }
 188         }
 189     }
 190
 191     // It is a failure if we got zero hashes or we somehow don't know the algorithm
 192     if hashes.is_empty() {
 193         return None;
 194     }
 195     let alg = match alg {
 196         Some(alg) => alg,
 197         _ => return None,
 198     };
 199
 200     // Otherwise all is well and we can return our results
 201     Some(CandidateHashes {
 202         alg,
 203         source: VerificationSource::DigestsFile(path.clone()),
 204         hashes,
 205     })
 206 }
 207
 208 /// Determine if the calculated hash matches any of the candidates.
 209 ///
 210 /// Ok result: the hash matches, and if the candidate has a filename, that matches too
 211 /// Maybe result: the hash matches but the filename does not
 212 /// Fail result: neither of the above
 213 pub fn verify_hash<'a>(calculated: &Hash, candidates: &'a CandidateHashes) -> Verification<'a> {
 214     let mut ok: Option<&CandidateHash> = None;
 215     let mut maybe: Option<&CandidateHash> = None;
 216     let mut messages = Vec::new();
 217
 218     for candidate in &candidates.hashes {
 219         if candidate.bytes == calculated.bytes {
 220             match candidate.filename {
 221                 None => ok = Some(candidate),
 222                 Some(ref candidate_filename) if candidate_filename == &calculated.filename => {
 223                     ok = Some(candidate)
 224                 }
 225                 Some(ref candidate_filename) => {
 226                     messages.push((
 227                         MessageLevel::Warning,
 228                         format!(
 229                             "The matched hash has filename '{}', which does not match the input.",
 230                             candidate_filename
 231                         ),
 232                     ));
 233                     maybe = Some(candidate);
 234                 }
 235             }
 236         }
 237     }
 238
 239     // Warn that a "successful" MD5 result is not necessarily great
 240     if candidates.alg == Algorithm::Md5 && (ok.is_some() || maybe.is_some()) {
 241         messages.push((
 242             MessageLevel::Note,
 243             "MD5 can easily be forged. Use a stronger algorithm if possible.".to_owned(),
 244         ))
 245     }
 246
 247     // If we got a full match, great
 248     if ok.is_some() {
 249         return Verification {
 250             match_level: MatchLevel::Ok,
 251             comparison_hash: ok,
 252             messages,
 253         };
 254     }
 255
 256     // Second priority, a "maybe" result
 257     if maybe.is_some() {
 258         return Verification {
 259             match_level: MatchLevel::Maybe,
 260             comparison_hash: maybe,
 261             messages,
 262         };
 263     }
 264
 265     // Otherwise we failed
 266     // If we only had one candidate hash, include it
 267     let comparison = match candidates.hashes.len() {
 268         1 => Some(&candidates.hashes[0]),
 269         _ => None,
 270     };
 271     Verification {
 272         match_level: MatchLevel::Fail,
 273         comparison_hash: comparison,
 274         messages,
 275     }
 276 }