Struct apple_xar::table_of_contents::TableOfContents

source · 
pub struct TableOfContents { /* private fields */ }
Expand description

An XML table of contents in a XAR file.

Implementations§

Parse XML table of contents from a reader.

Examples found in repository?
src/reader.rs (line 59)
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    pub fn new(mut reader: R) -> XarResult<Self> {
        let header = reader.ioread_with::<XarHeader>(scroll::BE)?;

        let mut header_extra = vec![0u8; header.size as usize - 28];
        reader.read_exact(&mut header_extra)?;

        // Following the header is a zlib compressed table of contents.
        // Unfortunately, serde_xml_rs takes ownership of the reader and doesn't
        // allow returning it. So we have to buffer decompressed data before feeding
        // it to the XML parser.
        let toc_reader = reader.take(header.toc_length_compressed);
        let mut toc_reader = flate2::read::ZlibDecoder::new(toc_reader);

        let mut toc_data = Vec::with_capacity(header.toc_length_uncompressed as _);
        toc_reader.read_to_end(&mut toc_data)?;

        let mut reader = toc_reader.into_inner().into_inner();
        let heap_start_offset = reader.stream_position()?;

        let toc = TableOfContents::from_reader(std::io::Cursor::new(toc_data))?;

        Ok(Self {
            reader,
            header,
            toc,
            heap_start_offset,
        })
    }

Resolve the complete list of files.

Files are sorted by their numerical ID, which should hopefully also be the order that file data occurs in the heap. Each elements consists of the full filename and the record.

Examples found in repository?
src/reader.rs (line 128)
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    pub fn files(&self) -> XarResult<Vec<(String, File)>> {
        self.toc.files()
    }

    /// Attempt to find the [File] entry for a given path in the archive.
    pub fn find_file(&self, filename: &str) -> XarResult<Option<File>> {
        Ok(self
            .toc
            .files()?
            .into_iter()
            .find_map(|(path, file)| if path == filename { Some(file) } else { None }))
    }

    /// Write a slice of the file to a writer.
    ///
    /// Offsets are relative from beginning of the file.
    fn write_file_slice(
        &mut self,
        offset: u64,
        size: usize,
        writer: &mut impl Write,
    ) -> XarResult<()> {
        self.reader.seek(SeekFrom::Start(offset))?;

        let mut remaining = size;
        let mut buffer = Vec::with_capacity(32768);
        buffer.resize(min(remaining, buffer.capacity()), 0);

        while remaining > 0 {
            self.reader.read_exact(&mut buffer)?;
            remaining -= buffer.len();
            writer.write_all(&buffer)?;

            unsafe {
                buffer.set_len(min(remaining, buffer.capacity()));
            }
        }

        Ok(())
    }

    /// Write a slice of the heap to a writer.
    fn write_heap_slice(
        &mut self,
        offset: u64,
        size: usize,
        writer: &mut impl Write,
    ) -> XarResult<()> {
        self.write_file_slice(self.heap_start_offset + offset, size, writer)
    }

    /// Write heap file data for a given file record to a writer.
    ///
    /// This will write the raw data backing a file as stored in the heap.
    /// There's a good chance the raw data is encoded/compressed.
    ///
    /// Returns the number of bytes written.
    pub fn write_file_data_heap_from_file(
        &mut self,
        file: &File,
        writer: &mut impl Write,
    ) -> XarResult<usize> {
        let data = file.data.as_ref().ok_or(Error::FileNoData)?;

        self.write_heap_slice(data.offset, data.length as _, writer)?;

        Ok(data.length as _)
    }

    /// Write heap file data for a given file ID to a writer.
    ///
    /// This is a wrapper around [Self::write_file_data_heap_from_file] that
    /// resolves the [File] given a file ID.
    pub fn write_file_data_heap_from_id(
        &mut self,
        id: u64,
        writer: &mut impl Write,
    ) -> XarResult<usize> {
        let file = self
            .toc
            .files()?
            .into_iter()
            .find(|(_, f)| f.id == id)
            .ok_or(Error::InvalidFileId)?
            .1;

        self.write_file_data_heap_from_file(&file, writer)
    }

    /// Write decoded file data for a given file record to a writer.
    ///
    /// This will call [Self::write_file_data_heap_from_file] and will decode
    /// that data stream, if the file data is encoded.
    pub fn write_file_data_decoded_from_file(
        &mut self,
        file: &File,
        writer: &mut impl Write,
    ) -> XarResult<usize> {
        let data = file.data.as_ref().ok_or(Error::FileNoData)?;

        let mut writer = match data.encoding.style.as_str() {
            "application/octet-stream" => Box::new(writer) as Box<dyn Write>,
            "application/x-bzip2" => {
                Box::new(bzip2::write::BzDecoder::new(writer)) as Box<dyn Write>
            }
            // The media type is arguably wrong, as there is no gzip header.
            "application/x-gzip" => {
                Box::new(flate2::write::ZlibDecoder::new(writer)) as Box<dyn Write>
            }
            "application/x-lzma" => Box::new(xz2::write::XzDecoder::new(writer)) as Box<dyn Write>,
            encoding => {
                return Err(Error::UnimplementedFileEncoding(encoding.to_string()));
            }
        };

        self.write_file_data_heap_from_file(file, &mut writer)
    }

    /// Write decoded file data for a given file ID to a writer.
    ///
    /// This is a wrapper for [Self::write_file_data_decoded_from_file] that locates
    /// the [File] entry given a file ID.
    pub fn write_file_data_decoded_from_id(
        &mut self,
        id: u64,
        writer: &mut impl Write,
    ) -> XarResult<usize> {
        let file = self
            .toc
            .files()?
            .into_iter()
            .find(|(_, f)| f.id == id)
            .ok_or(Error::InvalidFileId)?
            .1;

        self.write_file_data_decoded_from_file(&file, writer)
    }

    /// Resolve data for a given path.
    pub fn get_file_data_from_path(&mut self, path: &str) -> XarResult<Option<Vec<u8>>> {
        if let Some(file) = self.find_file(path)? {
            let mut buffer = Vec::<u8>::with_capacity(file.size.unwrap_or(0) as _);
            self.write_file_data_decoded_from_file(&file, &mut buffer)?;

            Ok(Some(buffer))
        } else {
            Ok(None)
        }
    }

    /// Unpack the contents of the XAR archive to a given directory.
    pub fn unpack(&mut self, dest_dir: impl AsRef<Path>) -> XarResult<()> {
        let dest_dir = dest_dir.as_ref();

        for (path, file) in self.toc.files()? {
            let dest_path = dest_dir.join(path);

            match file.file_type {
                FileType::Directory => {
                    std::fs::create_dir(&dest_path)?;
                }
                FileType::File => {
                    let mut fh = std::fs::File::create(&dest_path)?;
                    self.write_file_data_decoded_from_file(&file, &mut fh)?;
                }
                FileType::HardLink => return Err(Error::Unsupported("writing hard links")),
                FileType::Link => return Err(Error::Unsupported("writing symlinks")),
            }
        }

        Ok(())
    }
Examples found in repository?
src/signing.rs (line 162)
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    pub fn sign<W: Write>(
        &mut self,
        writer: &mut W,
        signing_key: &dyn KeyInfoSigner,
        signing_cert: &CapturedX509Certificate,
        time_stamp_url: Option<&Url>,
        certificates: impl Iterator<Item = CapturedX509Certificate>,
    ) -> XarResult<()> {
        let extra_certificates = certificates.collect::<Vec<_>>();

        // Base64 encoding of all public certificates.
        let chain = std::iter::once(signing_cert)
            .chain(extra_certificates.iter())
            .collect::<Vec<_>>();

        // Sending the same content to the Time-Stamp Server on every invocation might
        // raise suspicions. So randomize the input and thus the digest.
        let mut random = [0u8; 32];
        rand::thread_rng().fill_bytes(&mut random);
        let empty_digest = self.checksum_type.digest_data(&random)?;
        let digest_size = empty_digest.len() as u64;

        info!("performing empty RSA signature to calculate signature length");
        let rsa_signature_len = signing_key.try_sign(&empty_digest)?.as_ref().len();

        info!("performing empty CMS signature to calculate data length");
        let signer =
            SignerBuilder::new(signing_key, signing_cert.clone()).message_id_content(empty_digest);

        let signer = if let Some(time_stamp_url) = time_stamp_url {
            info!("using time-stamp server {}", time_stamp_url);
            signer.time_stamp_url(time_stamp_url.clone())?
        } else {
            signer
        };

        let cms_signature_len = SignedDataBuilder::default()
            .content_type(Oid(OID_ID_DATA.as_ref().into()))
            .signer(signer.clone())
            .certificates(extra_certificates.iter().cloned())
            .build_der()?
            .len();

        // Pad it a little because CMS signatures are variable size.
        let cms_signature_len = cms_signature_len + 512;

        // Now build up a new table of contents to sign.
        let mut toc = self.reader.table_of_contents().clone();
        toc.checksum = Checksum {
            style: self.checksum_type,
            offset: 0,
            size: digest_size,
        };

        let rsa_signature = Signature {
            style: SignatureStyle::Rsa,
            // The RSA signature goes right after the digest data.
            offset: digest_size,
            size: rsa_signature_len as _,
            key_info: KeyInfo::from_certificates(chain.iter().copied())?,
        };

        let cms_signature = Signature {
            style: SignatureStyle::Cms,
            // The CMS signature goes right after the RSA signature.
            offset: rsa_signature.offset + rsa_signature.size,
            size: cms_signature_len as _,
            key_info: KeyInfo::from_certificates(chain.iter().copied())?,
        };

        let mut current_offset = cms_signature.offset + cms_signature.size;

        toc.signature = Some(rsa_signature);
        toc.x_signature = Some(cms_signature);

        // Now go through and update file offsets. Files are nested. So we do a pass up
        // front to calculate all the offsets then we recursively descend and update all
        // references.
        let mut ids_to_offsets = HashMap::new();

        for (_, file) in self.reader.files()? {
            if let Some(data) = &file.data {
                ids_to_offsets.insert(file.id, current_offset);
                current_offset += data.length;
            }
        }

        toc.visit_files_mut(&|file: &mut File| {
            if let Some(data) = &mut file.data {
                data.offset = *ids_to_offsets
                    .get(&file.id)
                    .expect("file should have offset recorded");
            }
        });

        // The TOC should be all set up now. Let's serialize it so we can produce
        // a valid signature.
        warn!("generating new XAR table of contents XML");
        let toc_data = toc.to_xml()?;
        info!("table of contents size: {}", toc_data.len());

        let mut zlib = ZlibEncoder::new(Vec::new(), Compression::default());
        zlib.write_all(&toc_data)?;
        let toc_compressed = zlib.finish()?;

        let toc_digest = self.checksum_type.digest_data(&toc_compressed)?;

        // Sign it for real.
        let rsa_signature = signing_key.try_sign(&toc_digest)?;

        let mut cms_signature = SignedDataBuilder::default()
            .content_type(Oid(OID_ID_DATA.as_ref().into()))
            .signer(signer.message_id_content(toc_digest.clone()))
            .certificates(extra_certificates.iter().cloned())
            .build_der()?;

        match cms_signature.len().cmp(&cms_signature_len) {
            Ordering::Greater => {
                error!("real CMS signature overflowed allocated space for signature (please report this bug)");
                return Err(Error::Unsupported("CMS signature overflow"));
            }
            Ordering::Equal => {}
            Ordering::Less => {
                cms_signature
                    .extend_from_slice(&b"\0".repeat(cms_signature_len - cms_signature.len()));
            }
        }

        // Now let's write everything out.
        let mut header = *self.reader.header();
        header.checksum_algorithm_id = XarChecksum::from(self.checksum_type).into();
        header.toc_length_compressed = toc_compressed.len() as _;
        header.toc_length_uncompressed = toc_data.len() as _;

        writer.iowrite_with(header, scroll::BE)?;
        writer.write_all(&toc_compressed)?;
        writer.write_all(&toc_digest)?;
        writer.write_all(rsa_signature.as_ref())?;
        writer.write_all(&cms_signature)?;

        // And write all the files to the heap.
        for (path, file) in self.reader.files()? {
            if file.data.is_some() {
                info!("copying {} to output XAR", path);
                self.reader.write_file_data_heap_from_file(&file, writer)?;
            }
        }

        Ok(())
    }
Examples found in repository?
src/table_of_contents.rs (line 73)
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    pub fn to_xml(&self) -> XarResult<Vec<u8>> {
        let mut emitter = EmitterConfig::new().create_writer(std::io::BufWriter::new(vec![]));
        self.write_xml(&mut emitter)?;

        emitter
            .into_inner()
            .into_inner()
            .map_err(|e| Error::Io(std::io::Error::new(std::io::ErrorKind::Other, e)))
    }

Methods from Deref<Target = XarToC>§

Signatures present in the table of contents.

Examples found in repository?
src/table_of_contents.rs (line 143)
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    pub fn find_signature(&self, style: SignatureStyle) -> Option<&Signature> {
        self.signatures().into_iter().find(|sig| sig.style == style)
    }

Attempt to find a signature given a signature style.

Examples found in repository?
src/reader.rs (line 330)
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    pub fn rsa_signature(&mut self) -> XarResult<Option<(Vec<u8>, Vec<CapturedX509Certificate>)>> {
        if let Some(sig) = self.toc.find_signature(SignatureStyle::Rsa).cloned() {
            let mut data = Vec::<u8>::with_capacity(sig.size as _);
            self.write_heap_slice(sig.offset, sig.size as _, &mut data)?;

            let certs = sig.x509_certificates()?;

            Ok(Some((data, certs)))
        } else {
            Ok(None)
        }
    }

    /// Verifies the RSA signature in the archive.
    ///
    /// This verifies that the RSA signature in the archive, if present, is a valid signature
    /// for the archive's checksum data.
    ///
    /// The boolean return value indicates if signature validation was performed.
    pub fn verify_rsa_checksum_signature(&mut self) -> XarResult<bool> {
        let signed_data = self.checksum()?.1;

        if let Some((signature, certificates)) = self.rsa_signature()? {
            // The first certificate is the signing certificate.
            if let Some(cert) = certificates.get(0) {
                cert.verify_signed_data(signed_data, signature)?;
                Ok(true)
            } else {
                Ok(false)
            }
        } else {
            Ok(false)
        }
    }

    /// Attempt to resolve a cryptographic message syntax (CMS) signature.
    ///
    /// The data signed by the CMS signature is the raw data returned by [Self::checksum].
    pub fn cms_signature(&mut self) -> XarResult<Option<SignedData>> {
        if let Some(sig) = self.toc.find_signature(SignatureStyle::Cms).cloned() {
            let mut data = Vec::<u8>::with_capacity(sig.size as _);
            self.write_heap_slice(sig.offset, sig.size as _, &mut data)?;

            Ok(Some(SignedData::parse_ber(&data)?))
        } else {
            Ok(None)
        }
    }
Examples found in repository?
src/signing.rs (lines 151-157)
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    pub fn sign<W: Write>(
        &mut self,
        writer: &mut W,
        signing_key: &dyn KeyInfoSigner,
        signing_cert: &CapturedX509Certificate,
        time_stamp_url: Option<&Url>,
        certificates: impl Iterator<Item = CapturedX509Certificate>,
    ) -> XarResult<()> {
        let extra_certificates = certificates.collect::<Vec<_>>();

        // Base64 encoding of all public certificates.
        let chain = std::iter::once(signing_cert)
            .chain(extra_certificates.iter())
            .collect::<Vec<_>>();

        // Sending the same content to the Time-Stamp Server on every invocation might
        // raise suspicions. So randomize the input and thus the digest.
        let mut random = [0u8; 32];
        rand::thread_rng().fill_bytes(&mut random);
        let empty_digest = self.checksum_type.digest_data(&random)?;
        let digest_size = empty_digest.len() as u64;

        info!("performing empty RSA signature to calculate signature length");
        let rsa_signature_len = signing_key.try_sign(&empty_digest)?.as_ref().len();

        info!("performing empty CMS signature to calculate data length");
        let signer =
            SignerBuilder::new(signing_key, signing_cert.clone()).message_id_content(empty_digest);

        let signer = if let Some(time_stamp_url) = time_stamp_url {
            info!("using time-stamp server {}", time_stamp_url);
            signer.time_stamp_url(time_stamp_url.clone())?
        } else {
            signer
        };

        let cms_signature_len = SignedDataBuilder::default()
            .content_type(Oid(OID_ID_DATA.as_ref().into()))
            .signer(signer.clone())
            .certificates(extra_certificates.iter().cloned())
            .build_der()?
            .len();

        // Pad it a little because CMS signatures are variable size.
        let cms_signature_len = cms_signature_len + 512;

        // Now build up a new table of contents to sign.
        let mut toc = self.reader.table_of_contents().clone();
        toc.checksum = Checksum {
            style: self.checksum_type,
            offset: 0,
            size: digest_size,
        };

        let rsa_signature = Signature {
            style: SignatureStyle::Rsa,
            // The RSA signature goes right after the digest data.
            offset: digest_size,
            size: rsa_signature_len as _,
            key_info: KeyInfo::from_certificates(chain.iter().copied())?,
        };

        let cms_signature = Signature {
            style: SignatureStyle::Cms,
            // The CMS signature goes right after the RSA signature.
            offset: rsa_signature.offset + rsa_signature.size,
            size: cms_signature_len as _,
            key_info: KeyInfo::from_certificates(chain.iter().copied())?,
        };

        let mut current_offset = cms_signature.offset + cms_signature.size;

        toc.signature = Some(rsa_signature);
        toc.x_signature = Some(cms_signature);

        // Now go through and update file offsets. Files are nested. So we do a pass up
        // front to calculate all the offsets then we recursively descend and update all
        // references.
        let mut ids_to_offsets = HashMap::new();

        for (_, file) in self.reader.files()? {
            if let Some(data) = &file.data {
                ids_to_offsets.insert(file.id, current_offset);
                current_offset += data.length;
            }
        }

        toc.visit_files_mut(&|file: &mut File| {
            if let Some(data) = &mut file.data {
                data.offset = *ids_to_offsets
                    .get(&file.id)
                    .expect("file should have offset recorded");
            }
        });

        // The TOC should be all set up now. Let's serialize it so we can produce
        // a valid signature.
        warn!("generating new XAR table of contents XML");
        let toc_data = toc.to_xml()?;
        info!("table of contents size: {}", toc_data.len());

        let mut zlib = ZlibEncoder::new(Vec::new(), Compression::default());
        zlib.write_all(&toc_data)?;
        let toc_compressed = zlib.finish()?;

        let toc_digest = self.checksum_type.digest_data(&toc_compressed)?;

        // Sign it for real.
        let rsa_signature = signing_key.try_sign(&toc_digest)?;

        let mut cms_signature = SignedDataBuilder::default()
            .content_type(Oid(OID_ID_DATA.as_ref().into()))
            .signer(signer.message_id_content(toc_digest.clone()))
            .certificates(extra_certificates.iter().cloned())
            .build_der()?;

        match cms_signature.len().cmp(&cms_signature_len) {
            Ordering::Greater => {
                error!("real CMS signature overflowed allocated space for signature (please report this bug)");
                return Err(Error::Unsupported("CMS signature overflow"));
            }
            Ordering::Equal => {}
            Ordering::Less => {
                cms_signature
                    .extend_from_slice(&b"\0".repeat(cms_signature_len - cms_signature.len()));
            }
        }

        // Now let's write everything out.
        let mut header = *self.reader.header();
        header.checksum_algorithm_id = XarChecksum::from(self.checksum_type).into();
        header.toc_length_compressed = toc_compressed.len() as _;
        header.toc_length_uncompressed = toc_data.len() as _;

        writer.iowrite_with(header, scroll::BE)?;
        writer.write_all(&toc_compressed)?;
        writer.write_all(&toc_digest)?;
        writer.write_all(rsa_signature.as_ref())?;
        writer.write_all(&cms_signature)?;

        // And write all the files to the heap.
        for (path, file) in self.reader.files()? {
            if file.data.is_some() {
                info!("copying {} to output XAR", path);
                self.reader.write_file_data_heap_from_file(&file, writer)?;
            }
        }

        Ok(())
    }

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