chore: add error codes (#155)

* chore: add error codes

* chore: create errors with new Error()

* fix: better error testin

* refactor: simplify random bytes error checks

src/keys/index.js

@@ -6,6 +6,7 @@ require('node-forge/lib/asn1')
 require('node-forge/lib/rsa')
 require('node-forge/lib/pbe')
 const forge = require('node-forge/lib/forge')
+const errcode = require('err-code')
 
 exports = module.exports
 
@@ -18,9 +19,18 @@ const supportedKeys = {
 exports.supportedKeys = supportedKeys
 exports.keysPBM = keysPBM
 
-function isValidKeyType (keyType) {
-  const key = supportedKeys[keyType.toLowerCase()]
-  return key !== undefined
+const ErrMissingSecp256K1 = {
+  message: 'secp256k1 support requires libp2p-crypto-secp256k1 package',
+  code: 'ERR_MISSING_PACKAGE'
+}
+
+function typeToKey (type) {
+  let key = supportedKeys[type.toLowerCase()]
+  if (!key) {
+    const supported = Object.keys(supportedKeys).join(' / ')
+    throw errcode(new Error(`invalid or unsupported key type ${type}. Must be ${supported}`), 'ERR_UNSUPPORTED_KEY_TYPE')
+  }
+  return key
 }
 
 exports.keyStretcher = require('./key-stretcher')
@@ -28,24 +38,15 @@ exports.generateEphemeralKeyPair = require('./ephemeral-keys')
 
 // Generates a keypair of the given type and bitsize
 exports.generateKeyPair = async (type, bits) => { // eslint-disable-line require-await
-  let key = supportedKeys[type.toLowerCase()]
-
-  if (!key) {
-    throw new Error('invalid or unsupported key type')
-  }
-
-  return key.generateKeyPair(bits)
+  return typeToKey(type).generateKeyPair(bits)
 }
 
 // Generates a keypair of the given type and bitsize
 // seed is a 32 byte uint8array
 exports.generateKeyPairFromSeed = async (type, seed, bits) => { // eslint-disable-line require-await
-  let key = supportedKeys[type.toLowerCase()]
-  if (!key) {
-    throw new Error('invalid or unsupported key type')
-  }
+  const key = typeToKey(type)
   if (type.toLowerCase() !== 'ed25519') {
-    throw new Error('Seed key derivation is unimplemented for RSA or secp256k1')
+    throw errcode(new Error('Seed key derivation is unimplemented for RSA or secp256k1'), 'ERR_UNSUPPORTED_KEY_DERIVATION_TYPE')
   }
   return key.generateKeyPairFromSeed(seed, bits)
 }
@@ -65,20 +66,17 @@ exports.unmarshalPublicKey = (buf) => {
       if (supportedKeys.secp256k1) {
         return supportedKeys.secp256k1.unmarshalSecp256k1PublicKey(data)
       } else {
-        throw new Error('secp256k1 support requires libp2p-crypto-secp256k1 package')
+        throw errcode(new Error(ErrMissingSecp256K1.message), ErrMissingSecp256K1.code)
       }
     default:
-      throw new Error('invalid or unsupported key type')
+      typeToKey(decoded.Type) // throws because type is not supported
   }
 }
 
 // Converts a public key object into a protobuf serialized public key
 exports.marshalPublicKey = (key, type) => {
   type = (type || 'rsa').toLowerCase()
-  if (!isValidKeyType(type)) {
-    throw new Error('invalid or unsupported key type')
-  }
-
+  typeToKey(type) // check type
   return key.bytes
 }
 
@@ -97,27 +95,24 @@ exports.unmarshalPrivateKey = async (buf) => { // eslint-disable-line require-aw
       if (supportedKeys.secp256k1) {
         return supportedKeys.secp256k1.unmarshalSecp256k1PrivateKey(data)
       } else {
-        throw new Error('secp256k1 support requires libp2p-crypto-secp256k1 package')
+        throw errcode(new Error(ErrMissingSecp256K1.message), ErrMissingSecp256K1.code)
       }
     default:
-      throw new Error('invalid or unsupported key type')
+      typeToKey(decoded.Type) // throws because type is not supported
   }
 }
 
 // Converts a private key object into a protobuf serialized private key
 exports.marshalPrivateKey = (key, type) => {
   type = (type || 'rsa').toLowerCase()
-  if (!isValidKeyType(type)) {
-    throw new Error('invalid or unsupported key type')
-  }
-
+  typeToKey(type) // check type
   return key.bytes
 }
 
 exports.import = async (pem, password) => { // eslint-disable-line require-await
   const key = forge.pki.decryptRsaPrivateKey(pem, password)
   if (key === null) {
-    throw new Error('Cannot read the key, most likely the password is wrong or not a RSA key')
+    throw errcode(new Error('Cannot read the key, most likely the password is wrong or not a RSA key'), 'ERR_CANNOT_DECRYPT_PEM')
   }
   let der = forge.asn1.toDer(forge.pki.privateKeyToAsn1(key))
   der = Buffer.from(der.getBytes(), 'binary')