base64-utils.js

export class Base64DecoderUtils {
  constructor() {
    this.haveU8 = typeof Uint8Array === "function";
    this.decoder = undefined;
  }

  decode(a) {
    let isString = typeof a === "string";
    let i;
    if (this.decoder === undefined) {
      let b64 =
          "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
        ignore = "= \f\n\r\t\u00A0\u2028\u2029";
      this.decoder = [];
      for (i = 0; i < 64; ++i) this.decoder[b64.charCodeAt(i)] = i;
      for (i = 0; i < ignore.length; ++i)
        this.decoder[ignore.charCodeAt(i)] = -1;
      this.decoder["-".charCodeAt(0)] = this.decoder["+".charCodeAt(0)];
      this.decoder["_".charCodeAt(0)] = this.decoder["/".charCodeAt(0)];
    }

    let out = this.haveU8 ? new Uint8Array((a.length * 3) >> 2) : [];
    let bits = 0,
      char_count = 0,
      len = 0;
    for (i = 0; i < a.length; ++i) {
      let c = isString ? a.charCodeAt(i) : a[i];
      if (c === 61) break; // '='.charCodeAt(0)
      c = this.decoder[c];
      if (c === -1) continue;
      if (c === undefined) throw "Illegal character at offset " + i;
      bits |= c;
      if (++char_count >= 4) {
        out[len++] = bits >> 16;
        out[len++] = (bits >> 8) & 0xff;
        out[len++] = bits & 0xff;
        bits = 0;
        char_count = 0;
      } else {
        bits <<= 6;
      }
    }
    switch (char_count) {
      case 1:
        throw "Base64 encoding incomplete: at least 2 bits missing";
      case 2:
        out[len++] = bits >> 10;
        break;
      case 3:
        out[len++] = bits >> 16;
        out[len++] = (bits >> 8) & 0xff;
        break;
    }
    if (this.haveU8 && out.length > len) out = out.subarray(0, len); // in case it was originally longer because of ignored characters

    return out;
  }
}

export class Base64 {
  static re =
    /-----BEGIN [^-]+-----([A-Za-z0-9+/=\s]+)-----END [^-]+-----|begin-base64[^\n]+\n([A-Za-z0-9+/=\s]+)====|^([A-Za-z0-9+/=\s]+)$/;

  static decode(a) {
    let m = Base64.re.exec(a);
    if (m) {
      if (m[1]) a = m[1];
      else if (m[2]) a = m[2];
      else if (m[3]) a = m[3];
      else throw "RegExp out of sync";
    }
    return new Base64DecoderUtils().decode(a);
  }
}

export function parseCertificate(input) {
  const Base64CertRegex =
    /-----BEGIN [^-]+-----([A-Za-z0-9+/=\s]+)-----END [^-]+-----|begin-base64[^\n]+\n([A-Za-z0-9+/=\s]+)====|^([A-Za-z0-9+/=\s]+)$/;
  const matches = input.match(Base64CertRegex);
  if (!matches) {
    return null;
  }
  const [_, encoded1, encoded2, encoded3] = matches;
  const encoded = encoded1 || encoded2 || encoded3;
  return encoded.trim();
}