Use btcd cookie file for authentication

Alternatively use the btcd cookie file instead of username and password auth.
This need btcd.cookie to be set as cookie path in ckpool config file (see sample config).

If defined, the cookie auth has precedence but falls back to user auth in case of errors
(wrong path, wrong or invalid value).

ckpool.conf

@@ -4,6 +4,7 @@
 		"url" : "localhost:8332",
 		"auth" : "user",
 		"pass" : "pass",
+		"cookie": "/home/user/.bitcoin/.cookie",
 		"notify" : true
 	},
 	{

src/ckpool.c

@@ -1250,12 +1250,14 @@ static void parse_btcds(ckpool_t *ckp, const json_t *arr_val, const int arr_size
 	ckp->btcdurl = ckzalloc(sizeof(char *) * arr_size);
 	ckp->btcdauth = ckzalloc(sizeof(char *) * arr_size);
 	ckp->btcdpass = ckzalloc(sizeof(char *) * arr_size);
+	ckp->btcdcookie = ckzalloc(sizeof(char *) * arr_size);
 	ckp->btcdnotify = ckzalloc(sizeof(bool *) * arr_size);
 	for (i = 0; i < arr_size; i++) {
 		val = json_array_get(arr_val, i);
 		json_get_string(&ckp->btcdurl[i], val, "url");
 		json_get_string(&ckp->btcdauth[i], val, "auth");
 		json_get_string(&ckp->btcdpass[i], val, "pass");
+		json_get_string(&ckp->btcdcookie[i], val, "cookie");
 		json_get_bool(&ckp->btcdnotify[i], val, "notify");
 	}
 }
@@ -1724,6 +1726,7 @@ int main(int argc, char **argv)
 		ckp.btcdurl = ckzalloc(sizeof(char *));
 		ckp.btcdauth = ckzalloc(sizeof(char *));
 		ckp.btcdpass = ckzalloc(sizeof(char *));
+		ckp.btcdcookie = ckzalloc(sizeof(char *));
 		ckp.btcdnotify = ckzalloc(sizeof(bool));
 	}
 	for (i = 0; i < ckp.btcds; i++) {

src/ckpool.h

@@ -119,6 +119,7 @@ struct server_instance {
 	char *url;
 	char *auth;
 	char *pass;
+	char *cookie;
 	bool notify;
 	bool alive;
 	connsock_t cs;
@@ -225,6 +226,7 @@ struct ckpool_instance {
 	char **btcdurl;
 	char **btcdauth;
 	char **btcdpass;
+	char **btcdcookie;
 	bool *btcdnotify;
 	int blockpoll; // How frequently in ms to poll bitcoind for block updates
 	int nonce1length; // Extranonce1 length

src/generator.c

@@ -225,9 +225,15 @@ static bool server_alive(ckpool_t *ckp, server_instance_t *si, bool pinging)
 		LOGWARNING("Failed to extract address from %s", si->url);
 		return ret;
 	}
-	userpass = strdup(si->auth);
-	realloc_strcat(&userpass, ":");
-	realloc_strcat(&userpass, si->pass);
+	/* Use btcd cookie file for authentication */
+	if (si->cookie) {
+		LOGDEBUG("Using cookie auth: %s", si->cookie);
+		userpass = strdup(si->cookie);
+	} else {
+		userpass = strdup(si->auth);
+		realloc_strcat(&userpass, ":");
+		realloc_strcat(&userpass, si->pass);
+	}
 	dealloc(cs->auth);
 	cs->auth = http_base64(userpass);
 	if (!cs->auth) {
@@ -3257,6 +3263,34 @@ static void proxy_loop(proc_instance_t *pi)
 	return;
 }
 
+/* Read btcd cookie file from path, check if the path exists and
+ * return the cookie value. Otherwise, bail out with an error. */
+static char *read_cookie(const char *path)
+{
+	FILE *fp;
+	char buf[76];
+	char *cookie = NULL;
+
+	if(!path) {
+		return NULL;
+	}
+
+	fp = fopen(path, "r");
+	if (!fp) {
+		LOGERR("Failed to open cookie file %s", path);
+		return NULL;
+	}
+	cookie = fgets(buf, sizeof(buf), fp);
+	fclose(fp);
+
+	/* Check for valid cookie string */
+	if(!strstr(cookie, "__cookie__:")) {
+		return NULL;
+	}
+
+	return cookie;
+}
+
 /* Check which servers are alive, maintaining a connection with them and
  * reconnect if a higher priority one is available. */
 static void *server_watchdog(void *arg)
@@ -3297,12 +3331,15 @@ static void setup_servers(ckpool_t *ckp)
 	for (i = 0; i < ckp->btcds; i++) {
 		server_instance_t *si;
 		connsock_t *cs;
+		char *btcdcookie = NULL;
 
 		ckp->servers[i] = ckzalloc(sizeof(server_instance_t));
 		si = ckp->servers[i];
 		si->url = ckp->btcdurl[i];
 		si->auth = ckp->btcdauth[i];
 		si->pass = ckp->btcdpass[i];
+		if(btcdcookie = read_cookie(ckp->btcdcookie[i]))
+			si->cookie = strdup(btcdcookie);
 		si->notify = ckp->btcdnotify[i];
 		si->id = i;
 		cs = &si->cs;