From b6990631535e3c43b397c2a1888f926bd6af082b Mon Sep 17 00:00:00 2001
From: Mononaut <github@monospace.live>
Date: Mon, 3 Jun 2024 21:12:12 +0000
Subject: [PATCH] Experimental auto-push URL support

---
 .../push-transaction.component.ts             | 86 ++++++++++++++++++-
 frontend/src/app/master-page.module.ts        |  4 +
 2 files changed, 86 insertions(+), 4 deletions(-)

diff --git a/frontend/src/app/components/push-transaction/push-transaction.component.ts b/frontend/src/app/components/push-transaction/push-transaction.component.ts
index 2fbe356e8..03a050dfa 100644
--- a/frontend/src/app/components/push-transaction/push-transaction.component.ts
+++ b/frontend/src/app/components/push-transaction/push-transaction.component.ts
@@ -5,6 +5,8 @@ import { StateService } from '../../services/state.service';
 import { SeoService } from '../../services/seo.service';
 import { OpenGraphService } from '../../services/opengraph.service';
 import { seoDescriptionNetwork } from '../../shared/common.utils';
+import { ActivatedRoute, Router } from '@angular/router';
+import { RelativeUrlPipe } from '../../shared/pipes/relative-url/relative-url.pipe';
 
 @Component({
   selector: 'app-push-transaction',
@@ -23,6 +25,9 @@ export class PushTransactionComponent implements OnInit {
     public stateService: StateService,
     private seoService: SeoService,
     private ogService: OpenGraphService,
+    private route: ActivatedRoute,
+    private router: Router,
+    private relativeUrlPipe: RelativeUrlPipe,
   ) { }
 
   ngOnInit(): void {
@@ -33,27 +38,100 @@ export class PushTransactionComponent implements OnInit {
     this.seoService.setTitle($localize`:@@meta.title.push-tx:Broadcast Transaction`);
     this.seoService.setDescription($localize`:@@meta.description.push-tx:Broadcast a transaction to the ${this.stateService.network==='liquid'||this.stateService.network==='liquidtestnet'?'Liquid':'Bitcoin'}${seoDescriptionNetwork(this.stateService.network)} network using the transaction's hash.`);
     this.ogService.setManualOgImage('tx-push.jpg');
+
+    this.route.fragment.subscribe(async (fragment) => {
+      const fragmentParams = new URLSearchParams(fragment || '');
+      return this.handleColdcardPushTx(fragmentParams);
+    });
   }
 
-  postTx() {
+  async postTx(hex?: string): Promise<string> {
     this.isLoading = true;
     this.error = '';
     this.txId = '';
-    this.apiService.postTransaction$(this.pushTxForm.get('txHash').value)
+    return new Promise((resolve, reject) => {
+      this.apiService.postTransaction$(hex || this.pushTxForm.get('txHash').value)
       .subscribe((result) => {
         this.isLoading = false;
         this.txId = result;
         this.pushTxForm.reset();
+        resolve(this.txId);
       },
       (error) => {
         if (typeof error.error === 'string') {
           const matchText = error.error.match('"message":"(.*?)"');
-          this.error = matchText && matchText[1] || error.error;
+          this.error = 'Failed to broadcast transaction, reason: ' + (matchText && matchText[1] || error.error);
         } else if (error.message) {
-          this.error = error.message;
+          this.error = 'Failed to broadcast transaction, reason: ' + error.message;
         }
         this.isLoading = false;
+        reject(this.error);
       });
+    });
   }
 
+  private async handleColdcardPushTx(fragmentParams: URLSearchParams): Promise<boolean> {
+    // maybe conforms to Coldcard nfc-pushtx spec
+    if (fragmentParams && fragmentParams.get('t')) {
+      try {
+        const pushNetwork = fragmentParams.get('n');
+
+        // Redirect to the appropriate network-specific URL
+        if (this.stateService.network !== '' && !pushNetwork) {
+          this.router.navigateByUrl(`/pushtx#${fragmentParams.toString()}`);
+          return false;
+        } else if (this.stateService.network !== 'testnet' && pushNetwork === 'XTN') {
+          this.router.navigateByUrl(`/testnet/pushtx#${fragmentParams.toString()}`);
+          return false;
+        } else if (pushNetwork === 'XRT') {
+          this.error = 'Regtest is not supported';
+          return false;
+        } else if (pushNetwork && !['XTN', 'XRT'].includes(pushNetwork)) {
+          this.error = 'Invalid network';
+          return false;
+        }
+
+        const rawTx = this.base64UrlToU8Array(fragmentParams.get('t'));
+        if (!fragmentParams.get('c')) {
+          this.error = 'Missing checksum, URL is probably truncated';
+          return false;
+        }
+        const rawCheck = this.base64UrlToU8Array(fragmentParams.get('c'));
+        
+
+        // check checksum
+        const hashTx = await crypto.subtle.digest('SHA-256', rawTx);
+        if (this.u8ArrayToHex(new Uint8Array(hashTx.slice(24))) !== this.u8ArrayToHex(rawCheck)) {
+          this.error = 'Bad checksum, URL is probably truncated';
+          return false;
+        }
+
+        const hexTx = this.u8ArrayToHex(rawTx);
+        this.pushTxForm.get('txHash').setValue(hexTx);
+
+        try {
+          const txid = await this.postTx(hexTx);
+          this.router.navigate([this.relativeUrlPipe.transform('/tx'), txid]);
+        } catch (e) {
+          // error already handled
+          return false;
+        }
+
+        return true;
+      } catch (e) {
+        this.error = 'Failed to decode transaction';
+        return false;
+      }
+    }
+  }
+
+  private base64UrlToU8Array(base64Url: string): Uint8Array {
+    const base64 = base64Url.replace(/-/g, '+').replace(/_/g, '/').padEnd(base64Url.length + (4 - base64Url.length % 4) % 4, '=');
+    const binaryString = atob(base64);
+    return new Uint8Array([...binaryString].map(char => char.charCodeAt(0)));
+  }
+
+  private u8ArrayToHex(arr: Uint8Array): string {
+    return Array.from(arr).map(byte => byte.toString(16).padStart(2, '0')).join('');
+  }
 }
diff --git a/frontend/src/app/master-page.module.ts b/frontend/src/app/master-page.module.ts
index 012d2fa43..6ea8bfd93 100644
--- a/frontend/src/app/master-page.module.ts
+++ b/frontend/src/app/master-page.module.ts
@@ -32,6 +32,10 @@ const routes: Routes = [
         path: 'tx/push',
         component: PushTransactionComponent,
       },
+      {
+        path: 'pushtx',
+        component: PushTransactionComponent,
+      },
       {
         path: 'tx/test',
         component: TestTransactionsComponent,