From 767da8853189b6468915a602114e29b705cc0c25 Mon Sep 17 00:00:00 2001
From: surtur <a_mirre@utb.cz>
Date: Tue, 11 Jan 2022 05:38:02 +0100
Subject: [PATCH] accumulator: check entropy sources before adding

---
 accumulator.cpp | 27 +++++++++++++++++++++++++++
 accumulator.h   | 17 +++++++++++++----
 2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/accumulator.cpp b/accumulator.cpp
index 337cf32..e40d0a2 100644
--- a/accumulator.cpp
+++ b/accumulator.cpp
@@ -3,8 +3,12 @@
 
 #include "accumulator.h"
 
+#include <fmt/core.h>
+
 #include <chrono>
+#include <cstdint>
 #include <thread>
+#include <vector>
 
 namespace fortuna {
 namespace accumulator {
@@ -19,6 +23,29 @@ Accumulator::Accumulator() noexcept {
 Accumulator::~Accumulator() noexcept {};
 
 
+// check if given source id is an id of an already registered entropy source
+auto Accumulator::src_is_registered(const uint8_t& id) -> bool {
+	bool reg{false};
+	static uint8_t _src_id{};
+
+	for (auto& src_id: this->entropy_sources) {
+		if (src_id == id) {
+			reg = true;
+			_src_id = id;
+			break;
+		}
+	}
+
+	if (reg) {
+		fmt::print(
+			"[!] acc(add_source): entropy source \"{}\" already registered",
+			_src_id);
+		return true;
+	}
+
+	return false;
+}
+
 auto Accumulator::set_gen(fortuna::generator::Generator& gen) -> void {
 	this->Gen = std::move(&gen);
 }
diff --git a/accumulator.h b/accumulator.h
index e0dd60c..0f889c2 100644
--- a/accumulator.h
+++ b/accumulator.h
@@ -8,13 +8,17 @@
 #include <fmt/core.h>
 
 #include <algorithm>
+#include <cstdint>
 #include <exception>
+#include <vector>
 
 namespace fortuna {
 namespace accumulator {
 
 class Accumulator {
 private:
+	static constexpr const uint8_t MAX_SOURCES{255};
+	std::vector<uint8_t> entropy_sources{};
 	fortuna::generator::Generator* Gen;
 
 protected:
@@ -25,12 +29,17 @@ public:
 
 	auto add_source() -> void {
 		static uint src_id{this->src_count};
-		++src_count;
-		accumulator::Pool pools[32];
-		EventAdderImpl event_adder(src_id, pools);
-		[[maybe_unused]] bool scheduled;
+		// make really sure we don't and a duplicate src_id
+		if (src_id <= this->MAX_SOURCES && !src_is_registered(src_id)) {
+			++src_count;
+			accumulator::Pool pools[32];
+			EventAdderImpl event_adder(src_id, pools);
+			[[maybe_unused]] bool scheduled;
+		}
 	}
 
+	auto src_is_registered(const uint8_t& id) -> bool;
+
 	auto set_gen(fortuna::generator::Generator& Gen) -> void;
 
 	auto get_random_data(uint n_bytes) -> std::string;