ESP8266HTTPClient: add digest authentication example (#4112)

libraries/ESP8266HTTPClient/examples/DigestAuthorization/DigestAuthorization.ino

@@ -0,0 +1,133 @@
+/*
+    This sketch shows how to handle HTTP Digest Authorization.
+
+    Written by Parham Alvani and Sajjad Rahnama, 2018-01-07.
+
+   This example is released into public domain,
+   or, at your option, CC0 licensed.
+ */
+
+#include <ESP8266WiFi.h>
+
+#include <ESP8266HTTPClient.h>
+
+const char* ssid = "........";
+const char* ssidPassword = "........";
+
+const char *username = "admin";
+const char *password = "admin";
+
+const char *server = "http://httpbin.org";
+const char *uri = "/digest-auth/auth/admin/admin/MD5";
+
+String exractParam(String& authReq, const String& param, const char delimit){
+  int _begin = authReq.indexOf(param);
+  if (_begin==-1) return "";
+  return authReq.substring(_begin+param.length(),authReq.indexOf(delimit,_begin+param.length()));
+}
+
+String getCNonce(const int len) {
+    static const char alphanum[] =
+        "0123456789"
+        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+        "abcdefghijklmnopqrstuvwxyz";
+    String s = "";
+
+    for (int i = 0; i < len; ++i) {
+        s += alphanum[rand() % (sizeof(alphanum) - 1)];
+    }
+
+    return s;
+}
+
+String getDigestAuth(String& authReq, const String& username, const String& password, const String& uri, unsigned int counter) {
+  // extracting required parameters for RFC 2069 simpler Digest
+  String realm = exractParam(authReq, "realm=\"", '"');
+  String nonce = exractParam(authReq, "nonce=\"", '"');
+  String cNonce = getCNonce(8);
+
+  char nc[9];
+  snprintf(nc, sizeof(nc), "%08x", counter);
+
+  // parameters for the RFC 2617 newer Digest
+  MD5Builder md5;
+  md5.begin();
+  md5.add(username + ":" + realm + ":" + password);  // md5 of the user:realm:user
+  md5.calculate();
+  String h1 = md5.toString();
+
+  md5.begin();
+  md5.add(String("GET:") + uri);
+  md5.calculate();
+  String h2 = md5.toString();
+
+  md5.begin();
+  md5.add(h1 + ":" + nonce + ":" + String(nc) + ":" + cNonce + ":" + "auth" + ":" + h2);
+  md5.calculate();
+  String response = md5.toString();
+
+  String authorization = "Digest username=\"" + username + "\", realm=\"" + realm + "\", nonce=\"" + nonce +
+    "\", uri=\"" + uri + "\", algorithm=\"MD5\", qop=auth, nc=" + String(nc) + ", cnonce=\"" + cNonce + "\", response=\"" + response + "\"";
+  Serial.println(authorization);
+
+  return authorization;
+}
+
+void setup() {
+  Serial.begin(9600);
+
+  WiFi.mode(WIFI_STA);
+  WiFi.begin(ssid, ssidPassword);
+
+  while (WiFi.status() != WL_CONNECTED) {
+    delay(500);
+    Serial.print(".");
+  }
+
+  Serial.println("");
+  Serial.println("WiFi connected");
+  Serial.println("IP address: ");
+  Serial.println(WiFi.localIP());
+}
+
+void loop() {
+  HTTPClient http;
+
+  Serial.print("[HTTP] begin...\n");
+
+  // configure traged server and url
+  http.begin(String(server) + String(uri));
+
+
+  const char *keys[] = {"WWW-Authenticate"};
+  http.collectHeaders(keys, 1);
+
+  Serial.print("[HTTP] GET...\n");
+  // start connection and send HTTP header
+  int httpCode = http.GET();
+
+  if (httpCode > 0) {
+    String authReq = http.header("WWW-Authenticate");
+    Serial.println(authReq);
+
+    String authorization = getDigestAuth(authReq, String(username), String(password), String(uri), 1);
+
+    http.end();
+    http.begin(String(server) + String(uri));
+
+    http.addHeader("Authorization", authorization);
+
+    int httpCode = http.GET();
+    if (httpCode > 0) {
+      String payload = http.getString();
+      Serial.println(payload);
+    } else {
+      Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());
+    }
+  } else {
+    Serial.printf("[HTTP] GET... failed, error: %s\n", http.errorToString(httpCode).c_str());
+  }
+
+  http.end();
+  delay(10000);
+}