From 2a07c992ab66cbd49efe5f4f2d31446367f84784 Mon Sep 17 00:00:00 2001
From: DL6ER <dl6er@dl6er.de>
Date: Sat, 23 Nov 2019 19:15:23 +0100
Subject: [PATCH] Add option for whether authentication is needed for localhost
 requests. Defaults to false. (API_AUTH_FOR_LOCALHOST)

Signed-off-by: DL6ER <dl6er@dl6er.de>
---
 src/api/auth.c        | 29 +++++++++++++++++++++++++----
 src/api/http-common.c | 11 ++++++++++-
 src/config.c          | 14 ++++++++++++++
 src/config.h          |  1 +
 4 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/src/api/auth.c b/src/api/auth.c
index 95eec7b3..e66ee80f 100644
--- a/src/api/auth.c
+++ b/src/api/auth.c
@@ -39,10 +39,18 @@ static void generateRandomString(char *str, size_t size)
 // Can we validate this client?
 // Returns -1 if not authenticated or expired
 // Returns >= 0 for any valid authentication
+#define LOCALHOSTv4 "127.0.0.1"
+#define LOCALHOSTv6 "::1"
 int check_client_auth(struct mg_connection *conn)
 {
 	int user_id = -1;
 	const struct mg_request_info *request = mg_get_request_info(conn);
+
+	// Is the user requesting from localhost?
+	if(!httpsettings.api_auth_for_localhost && (strcmp(request->remote_addr, LOCALHOSTv4) == 0 ||
+	                                            strcmp(request->remote_addr, LOCALHOSTv6) == 0))
+		return API_MAX_CLIENTS;
+
 	// Does the client provide a user_id cookie?
 	int num;
 	if(http_get_cookie_int(conn, "user_id", &num) && num > -1 && num < API_MAX_CLIENTS)
@@ -136,10 +144,10 @@ int api_auth(struct mg_connection *conn)
 					logg("Registered new user: user_id %i valid_until: %s remote_addr %s",
 					user_id, timestr, auth_data[user_id].remote_addr);
 				}
-				else
-				{
-					logg("No free user slots available, not authenticating user");
-				}
+			}
+			if(user_id == -1)
+			{
+				logg("WARNING: No free slots available, not authenticating user");
 			}
 		}
 		else if(config.debug & DEBUG_API)
@@ -155,6 +163,19 @@ int api_auth(struct mg_connection *conn)
 		user_id = check_client_auth(conn);
 
 	int method = http_method(conn);
+	if(user_id == API_MAX_CLIENTS)
+	{
+		if(config.debug & DEBUG_API)
+			logg("Authentification: OK, localhost does not need auth.");
+		// We still have to send a cookie for the web interface to be happy
+		char *additional_headers = NULL;
+		if(asprintf(&additional_headers,
+		            "Set-Cookie: user_id=%u; Path=/; Max-Age=%u\r\n",
+		            API_MAX_CLIENTS, API_SESSION_EXPIRE) < 0)
+		{
+			return send_json_error(conn, 500, "internal_error", "Internal server error", NULL, NULL);
+		}
+	}
 	if(user_id > -1 && method == HTTP_GET)
 	{
 		if(config.debug & DEBUG_API)
diff --git a/src/api/http-common.c b/src/api/http-common.c
index 290835f1..94334578 100644
--- a/src/api/http-common.c
+++ b/src/api/http-common.c
@@ -83,7 +83,16 @@ int send_json_success(struct mg_connection *conn,
 {
 	cJSON *json = JSON_NEW_OBJ();
 	JSON_OBJ_REF_STR(json, "status", "success");
-	JSON_SEND_OBJECT_AND_HEADERS(json, additional_headers);
+
+	// Send additional headers if supplied
+	if(additional_headers == NULL)
+	{
+		JSON_SEND_OBJECT(json);
+	}
+	else
+	{
+		JSON_SEND_OBJECT_AND_HEADERS(json, additional_headers);
+	}
 }
 
 int send_http_internal_error(struct mg_connection *conn)
diff --git a/src/config.c b/src/config.c
index 40f20b05..c8014685 100644
--- a/src/config.c
+++ b/src/config.c
@@ -408,6 +408,20 @@ void read_FTLconf(void)
 		logg("   WEBACL: Allowing all access.");
 	}
 
+	// API_AUTH_FOR_LOALHOST
+	// defaults to: false
+	httpsettings.api_auth_for_localhost = false;
+	buffer = parse_FTLconf(fp, "API_AUTH_FOR_LOALHOST");
+
+	if(buffer != NULL && (strcasecmp(buffer, "yes") == 0 ||
+	                      strcasecmp(buffer, "true") == 0))
+		httpsettings.api_auth_for_localhost = true;
+
+	if(httpsettings.api_auth_for_localhost)
+		logg("   API_AUTH_FOR_LOCALHOST: Active");
+	else
+		logg("   API_AUTH_FOR_LOCALHOST: Inactive");
+
 	// Read DEBUG_... setting from pihole-FTL.conf
 	// This option should be the last one as it causes
 	// some rather verbose output into the log when
diff --git a/src/config.h b/src/config.h
index 27225b05..45a8b1b4 100644
--- a/src/config.h
+++ b/src/config.h
@@ -57,6 +57,7 @@ typedef struct httpsettings {
 	char *webroot;
 	char *webhome;
 	const char *acl;
+	bool api_auth_for_localhost;
 	char port[20]; // enough space for 2*(maximum length of number in a uint16_t = 5 characters) + ",[::]:" + NULL
 } httpsettingsStruct;