fix: implement checksum verification during post-install

Closes #118

Author: EricCrosson

.github/workflows/release.yml

@@ -140,16 +140,26 @@ jobs:
         cp target/${{ matrix.triple.target }}/release/monorepo builds/typescript-tools-${{ matrix.triple.target }}/
         tar -C builds -czvf dist/typescript-tools-${{ matrix.triple.target }}.tar.gz typescript-tools-${{ matrix.triple.target }}
 
-    - name: Create checksum
+    # Create a checksum of the tar archive for manual checksum verification of the archive before extraction.
+    - name: Create tar checksum
       run: shasum --algorithm 256 typescript-tools-${{ matrix.triple.target }}.tar.gz > typescript-tools-${{ matrix.triple.target }}-SHASUMS256.txt
       working-directory: ./dist
 
+    # Create a checksum of the binary for automatic checksum verification in the post-install hook. In this code
+    # path, the tar archive is streamed from the GitHub release page and the stream is untarred before a file
+    # is ever written to disk, to minimize disk usage. This makes it impossible to validate the checksum of the
+    # entire tar archive, so we calculate a checksum of the untarred binary instead.
+    - name: Create binary checksum
+      run: shasum --algorithm 256 --binary monorepo | tee ../../dist/typescript-tools-${{ matrix.triple.target }}-binary-SHASUMS256.txt
+      working-directory: ./builds/typescript-tools-${{ matrix.triple.target }}
+
     - name: Upload release artifacts
       uses: actions/upload-artifact@v3
       with:
         name: ${{ matrix.triple.target }}
         path: |
           dist/typescript-tools-${{ matrix.triple.target }}.tar.gz
+          dist/typescript-tools-${{ matrix.triple.target }}-binary-SHASUMS256.txt
           dist/typescript-tools-${{ matrix.triple.target }}-SHASUMS256.txt
         if-no-files-found: error
         retention-days: 1
@@ -180,8 +190,7 @@ jobs:
       working-directory: dist
 
     - name: Combine checksums
-      run: cat **/typescript-tools-*-SHASUMS256.txt | tee SHASUMS256.txt
-      working-directory: dist
+      run: cat dist/**/typescript-tools-*-SHASUMS256.txt | tee npm/SHASUMS256.txt
 
     - name: Invoke semantic-release
       env:

.releaserc.json

@@ -56,7 +56,7 @@
             "label": "aarch64-apple-darwin"
           },
           {
-            "path": "dist/SHASUMS256.txt",
+            "path": "npm/SHASUMS256.txt",
             "label": "SHASUMS256.txt"
           }
         ]

npm/binary-install.js

@@ -1,16 +1,12 @@
-const { existsSync, mkdirSync } = require("fs");
+const { createHash } = require("crypto");
+const { chmodSync, existsSync, mkdirSync, readFileSync } = require("fs");
 const { join } = require("path");
 const { spawnSync } = require("child_process");
 
 const axios = require("axios");
 const tar = require("tar");
 const rimraf = require("rimraf");
 
-const error = msg => {
-  console.error(msg);
-  process.exit(1);
-};
-
 class Binary {
   constructor(name, url) {
     let errors = [];
@@ -38,7 +34,8 @@ class Binary {
       });
       errorMsg +=
         '\n\nCorrect usage: new Binary("my-binary", "https://example.com/binary/download.tar.gz")';
-      error(errorMsg);
+      console.error(errorMsg);
+      process.exit(1);
     }
     this.url = url;
     this.name = name;
@@ -60,7 +57,9 @@ class Binary {
 
     // console.log(`Downloading release from ${this.url}`);
 
+    // Stream the file from the GitHub release page
     return axios({ ...fetchOptions, url: this.url, responseType: "stream" })
+      // untar the stream and write to disk
       .then(res => {
         return new Promise((resolve, reject) => {
           const sink = tar.x({ strip: 1, C: this.installDirectory });
@@ -69,17 +68,40 @@ class Binary {
           sink.on('error', err => reject(err));
         });
       })
+      // calculate a checksum of the untarred binary
+      .then(() => {
+        const fileBuffer = readFileSync(this.binaryPath);
+        const hashsum = createHash("sha256");
+        hashsum.update(fileBuffer);
+        const calculated_checksum = hashsum.digest('hex');
+
+        const advertised_checksums = readFileSync(join(__dirname, "SHASUMS256.txt"));
+
+        return new Promise((resolve, reject) => {
+          if (advertised_checksums.includes(calculated_checksum)) {
+            resolve();
+          } else {
+            chmodSync(this.binaryPath, 0o400);
+            console.error(`Calculated unexpected checksum ${calculated_checksum} for file ${this.binaryPath}`);
+            console.error('This file has been stripped of executable permissions but you should quarantine or delete it and open an issue.');
+            reject(new Error('Unexpected checksum'));
+          }
+        });
+      })
       .then(() => {
         // console.log(`${this.name} has been installed!`);
       })
-      .catch(e => {
-        error(`Error fetching release: ${e.message}`);
+      .catch(err => {
+        console.error(`Error fetching release:`);
+        console.error(err);
+        process.exit(1);
       });
   }
 
   run() {
     if (!existsSync(this.binaryPath)) {
-      error(`You must install ${this.name} before you can run it`);
+      console.error(`You must install ${this.name} before you can run it`);
+      process.exit(1);
     }
 
     const [, , ...args] = process.argv;
@@ -89,7 +111,8 @@ class Binary {
     const result = spawnSync(this.binaryPath, args, options);
 
     if (result.error) {
-      error(result.error);
+      console.error(result.error);
+      process.exit(1);
     }
 
     process.exit(result.status);