Ethereum address validation + unit test

* utility function for validate Ethereum addresses
* unit test

project.clj

@@ -40,7 +40,8 @@
                  [crypto-random "1.2.0"]
                  [crypto-equality "1.0.0"]
                  [cheshire "5.7.0"]
-                 [mpg "1.3.0"]]
+                 [mpg "1.3.0"]
+                 [pandect "0.6.1"]]
 
   :min-lein-version "2.0.0"
   :source-paths ["src/clj" "src/cljc"]

src/clj/commiteth/eth/core.clj

@@ -5,7 +5,8 @@
             [commiteth.config :refer [env]]
             [clojure.string :refer [join]]
             [clojure.tools.logging :as log]
-            [clojure.string :as str]))
+            [clojure.string :as str]
+            [pandect.core :as pandect]))
 
 (def eth-rpc-url "http://localhost:8545")
 (defn eth-account [] (:eth-account env))
@@ -104,3 +105,44 @@
   (let [data (apply format-call-params method-id params)
         value (format "0x%x" 1)]
     (send-transaction from contract value {:data data})))
+
+
+(defn hex-ch->num
+  [ch]
+  (read-string (str "0x" ch)))
+
+(defn strip-0x
+  [x]
+  (str/replace x #"(?i)^0x" ""))
+
+(defn upper-ch [ch]
+  (first (str/upper-case ch)))
+
+(defn lower-ch [ch]
+  (first (str/lower-case ch)))
+
+(defn valid-address?
+  "Validate given ethereum address. Checksum validation is performed
+  and input is case-sensitive"
+  [address]
+  (log/debug "valid-address?" address)
+  ;; logic based on
+  ;;  https://github.com/cilphex/ethereum-address/blob/master/index.js
+  (and (boolean (re-matches #"(?i)^(0x)?[0-9a-f]{40}$" address))
+       (let [addr (strip-0x address)
+             hash (pandect/keccak-256 (str/lower-case addr))]
+         (log/debug "address hash" hash "addr" addr)
+         (->>
+          (map-indexed (fn [idx _]
+                         (let [hash-ch-int (-> (nth hash idx)
+                                               (hex-ch->num))
+                               ch (nth addr idx)
+                               ch-lower (lower-ch ch)
+                               ch-upper (upper-ch ch)]
+                           (or (and (> hash-ch-int 7)
+                                    (not= ch-upper ch))
+                               (and (<= hash-ch-int 7)
+                                    (not= ch-lower ch)))))
+                       addr)
+          (filter true?)
+          (empty?)))))

test/clj/commiteth/test/eth.clj

@@ -0,0 +1,14 @@
+(ns commiteth.test.eth
+  (:require [clojure.test :refer :all]
+            [commiteth.eth.core :as eth]))
+
+(deftest test-address-validation
+  (testing "Short address is invalid"
+    (let [addr "0x34264362346364326423"]
+      (is (false? (eth/valid-address? addr)))))
+  (testing "Valid address is valid"
+    (let [addr "0xA1cab91b36bea34487c5670Bbd00a1Aa8196aeD8"]
+      (is (true? (eth/valid-address? addr)))))
+  (testing "Case sensitivity matters"
+    (let [addr "0xa1cab91b36bea34487c5670bbd00a1aa8196aed8"]
+      (is (false? (eth/valid-address? addr))))))