fix(dkim): New class BodyHashStream

examples/dkim-body-hash-stream.js

@@ -0,0 +1,24 @@
+'use strict';
+
+// sign and verify:
+//   $ node sign-and-verify.js /path/to/message.eml
+
+const fs = require('node:fs');
+const { BodyHashStream } = require('../lib/dkim/body');
+
+let file = process.argv[2];
+let eml = fs.createReadStream(file);
+
+let algo = process.argv[3] || false; // allowed: 'rsa-sha256', 'rsa-sha1', 'ed25519-sha256'
+
+let signer = new BodyHashStream('relaxed/relaxed', algo);
+
+eml.on('error', err => {
+    console.error(err);
+});
+
+signer.once('hash', hash => {
+    console.error('BODY HASH: ' + hash);
+});
+
+eml.pipe(signer).pipe(process.stdout);

lib/dkim/body/index.js

@@ -1,7 +1,9 @@
 'use strict';
 
-let { SimpleHash } = require('./simple');
-let { RelaxedHash } = require('./relaxed');
+const { SimpleHash } = require('./simple');
+const { RelaxedHash } = require('./relaxed');
+const { Transform } = require('node:stream');
+const { MessageParser } = require('../message-parser');
 
 const dkimBody = (canonicalization, ...options) => {
     canonicalization = (canonicalization || 'simple/simple').toString().split('/').pop().toLowerCase().trim();
@@ -18,4 +20,72 @@ const dkimBody = (canonicalization, ...options) => {
     }
 };
 
-module.exports = { dkimBody };
+class MessageHasher extends MessageParser {
+    constructor(canonicalization, ...options) {
+        super();
+        this.hasher = dkimBody(canonicalization, ...options);
+        this.bodyHash = null;
+    }
+
+    async nextChunk(chunk) {
+        this.hasher.update(chunk);
+    }
+
+    async finalChunk() {
+        this.bodyHash = this.hasher.digest('base64');
+    }
+}
+
+class BodyHashStream extends Transform {
+    constructor(canonicalization, ...options) {
+        super();
+
+        this.finished = false;
+        this.finishCb = null;
+
+        this.messageHasher = new MessageHasher(canonicalization, ...options);
+        this.bodyHash = null;
+        this.messageHasher.once('finish', () => this.finishHashing());
+        this.messageHasher.once('end', () => this.finishHashing());
+        this.messageHasher.once('error', err => this.destroy(err));
+    }
+
+    finishHashing() {
+        if (this.finished || !this.finishCb) {
+            return;
+        }
+        this.finished = true;
+        let done = this.finishCb;
+        this.finishCb = null;
+
+        this.bodyHash = this.messageHasher.bodyHash;
+        this.emit('hash', this.bodyHash);
+
+        done();
+    }
+
+    _transform(chunk, encoding, done) {
+        if (!chunk || !chunk.length) {
+            return done();
+        }
+
+        if (typeof chunk === 'string') {
+            chunk = Buffer.from(chunk, encoding);
+        }
+
+        if (this.messageHasher.write(chunk) === false) {
+            // wait for drain
+            return this.messageHasher.once('drain', done);
+        }
+
+        this.push(chunk);
+        done();
+    }
+
+    _flush(done) {
+        this.finishCb = done;
+        this.messageHasher.end();
+    }
+}
+
+module.exports = { dkimBody, BodyHashStream };