fix(cli/js/web): formData parser for binary files (#6015)

cli/js/web/fetch/multipart.ts

@@ -0,0 +1,120 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { DenoBlob } from "../blob.ts";
+import { TextEncoder, TextDecoder } from "../text_encoding.ts";
+import { getHeaderValueParams } from "../util.ts";
+
+const decoder = new TextDecoder();
+const encoder = new TextEncoder();
+const CR = "\r".charCodeAt(0);
+const LF = "\n".charCodeAt(0);
+
+interface MultipartHeaders {
+  headers: Headers;
+  disposition: Map<string, string>;
+}
+
+export class MultipartParser {
+  readonly boundary: string;
+  readonly boundaryChars: Uint8Array;
+  readonly body: Uint8Array;
+  constructor(body: Uint8Array, boundary: string) {
+    if (!boundary) {
+      throw new TypeError("multipart/form-data must provide a boundary");
+    }
+
+    this.boundary = `--${boundary}`;
+    this.body = body;
+    this.boundaryChars = encoder.encode(this.boundary);
+  }
+
+  #parseHeaders = (headersText: string): MultipartHeaders => {
+    const headers = new Headers();
+    const rawHeaders = headersText.split("\r\n");
+    for (const rawHeader of rawHeaders) {
+      const sepIndex = rawHeader.indexOf(":");
+      if (sepIndex < 0) {
+        continue; // Skip this header
+      }
+      const key = rawHeader.slice(0, sepIndex);
+      const value = rawHeader.slice(sepIndex + 1);
+      headers.set(key, value);
+    }
+
+    return {
+      headers,
+      disposition: getHeaderValueParams(
+        headers.get("Content-Disposition") ?? ""
+      ),
+    };
+  };
+
+  parse(): FormData {
+    const formData = new FormData();
+    let headerText = "";
+    let boundaryIndex = 0;
+    let state = 0;
+    let fileStart = 0;
+
+    for (let i = 0; i < this.body.length; i++) {
+      const byte = this.body[i];
+      const prevByte = this.body[i - 1];
+      const isNewLine = byte === LF && prevByte === CR;
+
+      if (state === 1 || state === 2 || state == 3) {
+        headerText += String.fromCharCode(byte);
+      }
+      if (state === 0 && isNewLine) {
+        state = 1;
+      } else if (state === 1 && isNewLine) {
+        state = 2;
+        const headersDone = this.body[i + 1] === CR && this.body[i + 2] === LF;
+
+        if (headersDone) {
+          state = 3;
+        }
+      } else if (state === 2 && isNewLine) {
+        state = 3;
+      } else if (state === 3 && isNewLine) {
+        state = 4;
+        fileStart = i + 1;
+      } else if (state === 4) {
+        if (this.boundaryChars[boundaryIndex] !== byte) {
+          boundaryIndex = 0;
+        } else {
+          boundaryIndex++;
+        }
+
+        if (boundaryIndex >= this.boundary.length) {
+          const { headers, disposition } = this.#parseHeaders(headerText);
+          const content = this.body.subarray(fileStart, i - boundaryIndex - 1);
+          // https://fetch.spec.whatwg.org/#ref-for-dom-body-formdata
+          const filename = disposition.get("filename");
+          const name = disposition.get("name");
+
+          state = 5;
+          // Reset
+          boundaryIndex = 0;
+          headerText = "";
+
+          if (!name) {
+            continue; // Skip, unknown name
+          }
+
+          if (filename) {
+            const blob = new DenoBlob([content], {
+              type: headers.get("Content-Type") || "application/octet-stream",
+            });
+            formData.append(name, blob, filename);
+          } else {
+            formData.append(name, decoder.decode(content));
+          }
+        }
+      } else if (state === 5 && isNewLine) {
+        state = 1;
+      }
+    }
+
+    return formData;
+  }
+}