mbedtls: add

Signed-off-by: Simon Rozman <simon@rozman.si>

include/stdex/mbedtls.hpp

@@ -0,0 +1,219 @@
+/*
+	SPDX-License-Identifier: MIT
+	Copyright © 2016-2025 Amebis
+*/
+
+#pragma once
+
+#include "compat.hpp"
+#include "exception.hpp"
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdocumentation-deprecated-sync"
+#endif
+#include <mbedtls/bignum.h>
+#include <mbedtls/ctr_drbg.h>
+#include <mbedtls/entropy.h>
+#include <mbedtls/error.h>
+#include <mbedtls/pk.h>
+#include <mbedtls/x509_crt.h>
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
+#ifdef MBEDTLS_USE_PSA_CRYPTO
+#include <psa/crypto.h>
+#endif
+#if !defined(_WIN32)
+#include <stdio.h>
+#include <unistd.h>
+#endif
+#include <stdexcept>
+
+namespace stdex
+{
+	namespace mbedtls
+	{
+		///
+		/// MbedTLS runtime error
+		///
+		class runtime_error : public stdex::num_runtime_error<int>
+		{
+		public:
+			///
+			/// Constructs an exception
+			///
+			/// \param[in] num  MbedTLS error code
+			///
+			runtime_error(error_type num) : stdex::num_runtime_error<int>(num, message(num))
+			{
+			}
+
+			///
+			/// Constructs an exception
+			///
+			/// \param[in] num  MbedTLS error code
+			/// \param[in] msg  Error message
+			///
+			runtime_error(error_type num, const std::string &msg) : stdex::num_runtime_error<int>(num, msg + ": " + message(num))
+			{
+			}
+
+			///
+			/// Constructs an exception
+			///
+			/// \param[in] num  MbedTLS error code
+			/// \param[in] msg  Error message
+			///
+			runtime_error(error_type num, const char *msg) : stdex::num_runtime_error<int>(num, std::string(msg) + ": " + message(num))
+			{
+			}
+
+		protected:
+			///
+			/// Returns a string explaining the meaning of a security result code
+			///
+			/// \sa [mbedtls_strerror function](https://mbed-ce.github.io/mbed-os/group__mbedtls__errors.html#ga8c41c149b77a4807115b19c2af858558)
+			///
+			static std::string message(error_type num)
+			{
+				char buf[1024];
+				memset(buf, 0, sizeof(buf));
+				mbedtls_strerror(num, buf, sizeof(buf));
+				return buf;
+			}
+		};
+
+		///
+		/// MbedTLS entropy context 
+		///
+		class entropy_context : public mbedtls_entropy_context
+		{
+		public:
+			///
+			/// Initializes MbedTLS entropy context
+			///
+			/// \sa [mbedtls_entropy_init](https://mbed-ce.github.io/mbed-os/group__mbedtls__entropy__module.html#gaa901e027093c6fe65dee5760db78aced)
+			/// 
+			entropy_context()
+			{
+				mbedtls_entropy_init(this);
+	#if !defined(_WIN32) && defined(MBEDTLS_FS_IO)
+				int ret = mbedtls_entropy_add_source(this, dev_random_entropy_poll, NULL, 32, MBEDTLS_ENTROPY_SOURCE_STRONG);
+				if (ret != 0)
+					throw runtime_error(ret, "mbedtls_entropy_add_source failed");
+	#endif
+			}
+
+			///
+			/// Frees MbedTLS entropy context
+			///
+			/// \sa [mbedtls_entropy_free](https://mbed-ce.github.io/mbed-os/group__mbedtls__entropy__module.html#ga06778439f8a0e2daa2d3b444e06ad8dd)
+			/// 
+			~entropy_context()
+			{
+				mbedtls_entropy_free(this);
+			}
+
+		protected:
+	#if !defined(_WIN32) && defined(MBEDTLS_FS_IO)
+			static int dev_random_entropy_poll(void* data, unsigned char* output, size_t len, size_t* olen)
+			{
+				_Unreferenced_(data);
+				*olen = 0;
+				FILE* file = fopen("/dev/random", "rb");
+				if (file == NULL)
+					return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
+				size_t left = len;
+				unsigned char* p = output;
+				while (left) {
+					// /dev/random can return much less than requested. If so, try again.
+					size_t ret = fread(p, 1, left, file);
+					if (ret == 0 && ferror(file)) {
+						fclose(file);
+						return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
+					}
+					p += ret;
+					left -= ret;
+					if (!left)
+						break;
+					sleep(1);
+				}
+				fclose(file);
+				*olen = len;
+				return 0;
+			}
+	#endif
+		};
+
+		///
+		/// The MbedTLS CTR_DRBG context structure
+		///
+		struct ctr_drbg_context : public mbedtls_ctr_drbg_context
+		{
+			ctr_drbg_context() { mbedtls_ctr_drbg_init(this); }
+			~ctr_drbg_context() { mbedtls_ctr_drbg_free(this); }
+		};
+
+		///
+		/// MbedTLS MPI
+		///
+		struct mpi : public mbedtls_mpi
+		{
+			mpi() { mbedtls_mpi_init(this); }
+			~mpi() { mbedtls_mpi_free(this); }
+		};
+
+		///
+		/// MbedTLS public key container
+		///
+		struct pk_context : public mbedtls_pk_context
+		{
+			pk_context() { mbedtls_pk_init(this); }
+			~pk_context() { mbedtls_pk_free(this); }
+		};
+
+		///
+		/// MbedTLS container for an X.509 certificate
+		///
+		struct x509_crt : public mbedtls_x509_crt
+		{
+			x509_crt() { mbedtls_x509_crt_init(this); }
+			~x509_crt() { mbedtls_x509_crt_free(this); }
+		};
+
+		///
+		/// MbedTLS Container for writing a certificate (CRT)
+		///
+		struct x509write_cert : public mbedtls_x509write_cert
+		{
+			x509write_cert() { mbedtls_x509write_crt_init(this); }
+			~x509write_cert() { mbedtls_x509write_crt_free(this); }
+		};
+
+		///
+		/// MbedTLS global initializer
+		///
+		class initializer
+		{
+		public:
+			///
+			/// Initializes MbedTLS library
+			/// 
+			initializer()
+			{
+#ifdef MBEDTLS_USE_PSA_CRYPTO
+				auto status = psa_crypto_init();
+				if (status != PSA_SUCCESS)
+					throw runtime_error("Failed to initialize PSA Crypto implementation");
+#endif
+			}
+
+			~initializer()
+			{
+#ifdef MBEDTLS_USE_PSA_CRYPTO
+				mbedtls_psa_crypto_free();
+#endif
+			}
+		};
+	}
+}