Added base64 encoded attachment support (#966)

[signal-cli] / lib / src / main / java / org / asamk / signal / manager / util / DataURI.java

diff --git a/lib/src/main/java/org/asamk/signal/manager/util/DataURI.java b/lib/src/main/java/org/asamk/signal/manager/util/DataURI.java
new file mode 100644 (file)
index 0000000..04d4bbc
--- /dev/null
+++ b/lib/src/main/java/org/asamk/signal/manager/util/DataURI.java
@@ -0,0 +1,70 @@
+package org.asamk.signal.manager.util;
+
+import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+@SuppressWarnings({"java:S6218"})
+public record DataURI(String mediaType, Map<String, String> parameter, byte[] data) {
+
+    public static final Pattern DATA_URI_PATTERN = Pattern.compile(
+            "\\Adata:(?<type>.+?/.+?)?(?<parameters>;.+?=.+?)?(?<base64>;base64)?,(?<data>.+)\\z",
+            Pattern.CASE_INSENSITIVE);
+    public static final Pattern PARAMETER_PATTERN = Pattern.compile("\\G;(?<key>.+)=(?<value>.+)",
+            Pattern.CASE_INSENSITIVE);
+    public static final String DEFAULT_TYPE = "text/plain";
+
+    /**
+     * Generates a new {@link DataURI} object that follows
+     * <a href="https://datatracker.ietf.org/doc/html/rfc2397">RFC 2397</a> from the given string.
+     * <p>
+     * The {@code dataURI} must be of the form:
+     * <p>
+     * {@code
+     * data:[<mediatype>][;base64],<data>
+     * }
+     * <p>
+     * The {@code <mediatype>} is an Internet media type specification (with
+     * optional parameters.) The appearance of ";base64" means that the data
+     * is encoded as base64. Without ";base64", the data is represented using (ASCII) URL Escaped encoding.
+     * If {@code <mediatype>} is omitted, it defaults to {@link DataURI#DEFAULT_TYPE}.
+     * Parameter values should use the URL Escaped encoding.
+     *
+     * @param dataURI the data URI
+     * @return a data URI object
+     * @throws IllegalArgumentException if the given string is not a valid data URI
+     */
+    public static DataURI of(final String dataURI) {
+        final var matcher = DATA_URI_PATTERN.matcher(dataURI);
+
+        if (!matcher.find()) {
+            throw new IllegalArgumentException("The given string is not a valid data URI.");
+        }
+
+        final Map<String, String> parameters = new HashMap<>();
+        final var params = matcher.group("parameters");
+        if (params != null) {
+            final Matcher paramsMatcher = PARAMETER_PATTERN.matcher(params);
+            while (paramsMatcher.find()) {
+                final var key = paramsMatcher.group("key");
+                final var value = URLDecoder.decode(paramsMatcher.group("value"), StandardCharsets.UTF_8);
+                parameters.put(key, value);
+            }
+        }
+
+        final boolean isBase64 = matcher.group("base64") != null;
+        final byte[] data;
+        if (isBase64) {
+            data = Base64.getDecoder().decode(matcher.group("data").getBytes(StandardCharsets.UTF_8));
+        } else {
+            data = URLDecoder.decode(matcher.group("data"), StandardCharsets.UTF_8).getBytes(StandardCharsets.UTF_8);
+        }
+
+        return new DataURI(Optional.ofNullable(matcher.group("type")).orElse(DEFAULT_TYPE), parameters, data);
+    }
+}