From 683f65f8ac06148eb9fa283309840e16ec3f421d Mon Sep 17 00:00:00 2001
From: Sergey Lyubka <cpq@users.noreply.github.com>
Date: Sat, 31 Aug 2024 12:21:12 +0100
Subject: [PATCH] Make mg_random() fallible. Abort TLS on weak RNG

---
 examples/infineon/infineon-xmc7200/hal.c      |  3 +-
 .../same54-xpro/device-dashboard/main.c       |  3 +-
 .../microchip/same54-xpro/mqtt-client/main.c  |  3 +-
 .../frdm-mcxn947-make-baremetal-builtin/hal.c |  3 +-
 .../frdm-mcxn947-make-freertos-builtin/hal.c  |  3 +-
 .../source/hal.c                              |  3 +-
 .../source/hal.c                              |  3 +-
 .../rt1020-evk-make-baremetal-builtin/main.c  |  3 +-
 .../rt1020-evk-make-freertos-builtin/main.c   |  3 +-
 .../rt1060-evk-make-baremetal-builtin/main.c  |  4 +-
 .../rt1060-evk-make-freertos-builtin/main.c   |  3 +-
 .../source/main.c                             |  3 +-
 .../ek-ra6m4-make-baremetal-builtin/hal.c     |  3 +-
 examples/rp2040/pico-w5500/main.c             |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../stm32/nucleo-f429zi-keil-baremetal/main.c |  3 +-
 .../stm32/nucleo-f429zi-keil-freertos/main.c  |  3 +-
 .../main.c                                    |  5 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../stm32/nucleo-f746zg-keil-baremetal/main.c |  3 +-
 .../nucleo-f746zg-keil-freertos-lwip/main.c   |  9 ++--
 .../nucleo-f746zg-keil-freertos-tcp/main.c    |  9 ++--
 .../stm32/nucleo-f746zg-keil-freertos/main.c  |  3 +-
 .../main.c                                    | 12 ++---
 .../nucleo-f746zg-keil-freertos_cmsis2/main.c |  3 +-
 .../stm32/nucleo-f746zg-keil-rtx-mdk/main.c   |  9 ++--
 examples/stm32/nucleo-f746zg-keil-rtx/main.c  |  3 +-
 .../stm32/nucleo-f746zg-keil-rtx5-lwip/main.c | 12 ++---
 .../stm32/nucleo-f746zg-keil-rtx5-mdk/main.c  | 10 ++--
 examples/stm32/nucleo-f746zg-keil-rtx5/main.c |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  5 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../nucleo-f746zg-make-freertos-tcp/main.c    |  3 +-
 .../nucleo-g031-make-baremetal-builtin/main.c |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../Core/Src/main.c                           |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../main.c                                    |  3 +-
 .../wch/ch32v307-make-baremetal-builtin/hal.c |  3 +-
 mongoose.c                                    | 47 +++++++++++++++----
 mongoose.h                                    | 20 ++++++--
 src/arch_win32.h                              | 18 ++++++-
 src/tls_builtin.c                             |  8 ++--
 src/util.c                                    | 39 +++++++++++++--
 src/util.h                                    |  2 +-
 test/Makefile                                 | 13 ++---
 tutorials/http/http-server/Makefile           |  7 ++-
 62 files changed, 253 insertions(+), 111 deletions(-)

diff --git a/examples/infineon/infineon-xmc7200/hal.c b/examples/infineon/infineon-xmc7200/hal.c
index d0240e6a..2755b460 100644
--- a/examples/infineon/infineon-xmc7200/hal.c
+++ b/examples/infineon/infineon-xmc7200/hal.c
@@ -8,11 +8,12 @@ void SysTick_Handler(void) {       // SyStick IRQ handler, triggered every 1ms
   s_ticks++;
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
diff --git a/examples/microchip/same54-xpro/device-dashboard/main.c b/examples/microchip/same54-xpro/device-dashboard/main.c
index 14e54b49..c56150bb 100644
--- a/examples/microchip/same54-xpro/device-dashboard/main.c
+++ b/examples/microchip/same54-xpro/device-dashboard/main.c
@@ -22,11 +22,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/microchip/same54-xpro/mqtt-client/main.c b/examples/microchip/same54-xpro/mqtt-client/main.c
index 1f86bc32..037c5d7a 100644
--- a/examples/microchip/same54-xpro/mqtt-client/main.c
+++ b/examples/microchip/same54-xpro/mqtt-client/main.c
@@ -24,11 +24,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void fn(struct mg_connection *c, int ev, void *ev_data) {
diff --git a/examples/nxp/frdm-mcxn947-make-baremetal-builtin/hal.c b/examples/nxp/frdm-mcxn947-make-baremetal-builtin/hal.c
index aa465716..45560b09 100644
--- a/examples/nxp/frdm-mcxn947-make-baremetal-builtin/hal.c
+++ b/examples/nxp/frdm-mcxn947-make-baremetal-builtin/hal.c
@@ -9,11 +9,12 @@ void SysTick_Handler(void) {       // SyStick IRQ handler, triggered every 1ms
 }
 
 #if 0
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 #endif
 
diff --git a/examples/nxp/frdm-mcxn947-make-freertos-builtin/hal.c b/examples/nxp/frdm-mcxn947-make-freertos-builtin/hal.c
index 3c32b0a3..a1ff1914 100644
--- a/examples/nxp/frdm-mcxn947-make-freertos-builtin/hal.c
+++ b/examples/nxp/frdm-mcxn947-make-freertos-builtin/hal.c
@@ -9,11 +9,12 @@ void SysTick_Handler(void) {       // SyStick IRQ handler, triggered every 1ms
   s_ticks++;
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
diff --git a/examples/nxp/frdm-mcxn947-xpresso-baremetal-builtin/source/hal.c b/examples/nxp/frdm-mcxn947-xpresso-baremetal-builtin/source/hal.c
index aa465716..45560b09 100644
--- a/examples/nxp/frdm-mcxn947-xpresso-baremetal-builtin/source/hal.c
+++ b/examples/nxp/frdm-mcxn947-xpresso-baremetal-builtin/source/hal.c
@@ -9,11 +9,12 @@ void SysTick_Handler(void) {       // SyStick IRQ handler, triggered every 1ms
 }
 
 #if 0
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 #endif
 
diff --git a/examples/nxp/frdm-mcxn947-xpresso-freertos-builtin/source/hal.c b/examples/nxp/frdm-mcxn947-xpresso-freertos-builtin/source/hal.c
index 316721b2..9e6903b8 100644
--- a/examples/nxp/frdm-mcxn947-xpresso-freertos-builtin/source/hal.c
+++ b/examples/nxp/frdm-mcxn947-xpresso-freertos-builtin/source/hal.c
@@ -9,11 +9,12 @@ void SysTick_Handler(void) {       // SyStick IRQ handler, triggered every 1ms
   s_ticks++;
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
diff --git a/examples/nxp/rt1020-evk-make-baremetal-builtin/main.c b/examples/nxp/rt1020-evk-make-baremetal-builtin/main.c
index 3fd164e5..1fca6513 100644
--- a/examples/nxp/rt1020-evk-make-baremetal-builtin/main.c
+++ b/examples/nxp/rt1020-evk-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 static void timer_fn(void *arg) {
   gpio_toggle(LED);                                      // Blink LED
diff --git a/examples/nxp/rt1020-evk-make-freertos-builtin/main.c b/examples/nxp/rt1020-evk-make-freertos-builtin/main.c
index 2ef15ff7..9a497361 100644
--- a/examples/nxp/rt1020-evk-make-freertos-builtin/main.c
+++ b/examples/nxp/rt1020-evk-make-freertos-builtin/main.c
@@ -7,11 +7,12 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/nxp/rt1060-evk-make-baremetal-builtin/main.c b/examples/nxp/rt1060-evk-make-baremetal-builtin/main.c
index 3fd164e5..7a66465a 100644
--- a/examples/nxp/rt1060-evk-make-baremetal-builtin/main.c
+++ b/examples/nxp/rt1060-evk-make-baremetal-builtin/main.c
@@ -16,12 +16,14 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
+
 static void timer_fn(void *arg) {
   gpio_toggle(LED);                                      // Blink LED
   struct mg_tcpip_if *ifp = arg;                         // And show
diff --git a/examples/nxp/rt1060-evk-make-freertos-builtin/main.c b/examples/nxp/rt1060-evk-make-freertos-builtin/main.c
index 497f6fbe..96be22d6 100644
--- a/examples/nxp/rt1060-evk-make-freertos-builtin/main.c
+++ b/examples/nxp/rt1060-evk-make-freertos-builtin/main.c
@@ -15,11 +15,12 @@ void SysTick_Handler(void) {
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/nxp/rt1060-evk-xpresso-baremetal-builtin/source/main.c b/examples/nxp/rt1060-evk-xpresso-baremetal-builtin/source/main.c
index c83c335f..ba76eaca 100644
--- a/examples/nxp/rt1060-evk-xpresso-baremetal-builtin/source/main.c
+++ b/examples/nxp/rt1060-evk-xpresso-baremetal-builtin/source/main.c
@@ -33,8 +33,9 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   TRNG_GetRandomData(TRNG, buf, len);  // Init by BOARD_InitBootPeripherals()
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/renesas/ek-ra6m4-make-baremetal-builtin/hal.c b/examples/renesas/ek-ra6m4-make-baremetal-builtin/hal.c
index a326f37f..ac8d6b0b 100644
--- a/examples/renesas/ek-ra6m4-make-baremetal-builtin/hal.c
+++ b/examples/renesas/ek-ra6m4-make-baremetal-builtin/hal.c
@@ -47,11 +47,12 @@ void SysTick_Handler(void) {  // SyStick IRQ handler, triggered every 1ms
 }
 
 #if 0
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 #endif
 
diff --git a/examples/rp2040/pico-w5500/main.c b/examples/rp2040/pico-w5500/main.c
index 3c79e67f..81586803 100644
--- a/examples/rp2040/pico-w5500/main.c
+++ b/examples/rp2040/pico-w5500/main.c
@@ -26,11 +26,12 @@ static uint8_t spi_txn(void *spi, uint8_t byte) {
   return result;
 }
 
-void mg_random(void *buf, size_t len) {
+bool mg_random(void *buf, size_t len) {
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = get_rand_32();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f429zi-cube-baremetal-builtin/Core/Src/main.c b/examples/stm32/nucleo-f429zi-cube-baremetal-builtin/Core/Src/main.c
index 3bab391a..b44edf0a 100644
--- a/examples/stm32/nucleo-f429zi-cube-baremetal-builtin/Core/Src/main.c
+++ b/examples/stm32/nucleo-f429zi-cube-baremetal-builtin/Core/Src/main.c
@@ -76,13 +76,14 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return (uint64_t)HAL_GetTick();     // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f429zi-cube-freertos-builtin/Core/Src/main.c b/examples/stm32/nucleo-f429zi-cube-freertos-builtin/Core/Src/main.c
index 335b2cc0..86a95492 100644
--- a/examples/stm32/nucleo-f429zi-cube-freertos-builtin/Core/Src/main.c
+++ b/examples/stm32/nucleo-f429zi-cube-freertos-builtin/Core/Src/main.c
@@ -90,13 +90,14 @@ void server(void *argument);
 
 /* Private user code ---------------------------------------------------------*/
 /* USER CODE BEGIN 0 */
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Src/main.c b/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Src/main.c
index 22cf18a9..0d20e994 100644
--- a/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Src/main.c
+++ b/examples/stm32/nucleo-f429zi-cube-freertos-lwip/Core/Src/main.c
@@ -70,13 +70,14 @@ void blinker(void const * argument);
 
 /* Private user code ---------------------------------------------------------*/
 /* USER CODE BEGIN 0 */
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 /* USER CODE END 0 */
diff --git a/examples/stm32/nucleo-f429zi-keil-baremetal/main.c b/examples/stm32/nucleo-f429zi-keil-baremetal/main.c
index 8ae1eb69..cd0538b0 100644
--- a/examples/stm32/nucleo-f429zi-keil-baremetal/main.c
+++ b/examples/stm32/nucleo-f429zi-keil-baremetal/main.c
@@ -11,13 +11,14 @@ uint64_t mg_millis(void) {          // Let Mongoose use our uptime function
   return (uint64_t) HAL_GetTick();  // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f429zi-keil-freertos/main.c b/examples/stm32/nucleo-f429zi-keil-freertos/main.c
index 9b368493..6cf2dbbc 100644
--- a/examples/stm32/nucleo-f429zi-keil-freertos/main.c
+++ b/examples/stm32/nucleo-f429zi-keil-freertos/main.c
@@ -17,13 +17,14 @@ void SysTick_Handler(void) {
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f429zi-make-baremetal-builtin-rndis/main.c b/examples/stm32/nucleo-f429zi-make-baremetal-builtin-rndis/main.c
index 4c7f689c..74cadc70 100644
--- a/examples/stm32/nucleo-f429zi-make-baremetal-builtin-rndis/main.c
+++ b/examples/stm32/nucleo-f429zi-make-baremetal-builtin-rndis/main.c
@@ -22,11 +22,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 bool tud_network_recv_cb(const uint8_t *buf, uint16_t len) {
@@ -80,7 +81,7 @@ int main(void) {
   gpio_output(LED);               // Setup blue LED
   uart_init(UART_DEBUG, 115200);  // Initialise debug printf
 
-  struct mg_mgr mgr;        // Initialise 
+  struct mg_mgr mgr;        // Initialise
   mg_mgr_init(&mgr);        // Mongoose event manager
   mg_log_set(MG_LL_DEBUG);  // Set log level
 
diff --git a/examples/stm32/nucleo-f429zi-make-baremetal-builtin/main.c b/examples/stm32/nucleo-f429zi-make-baremetal-builtin/main.c
index 19ad4a75..0dca9f1c 100644
--- a/examples/stm32/nucleo-f429zi-make-baremetal-builtin/main.c
+++ b/examples/stm32/nucleo-f429zi-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f429zi-make-freertos-builtin/main.c b/examples/stm32/nucleo-f429zi-make-freertos-builtin/main.c
index 75798cef..58382cba 100644
--- a/examples/stm32/nucleo-f429zi-make-freertos-builtin/main.c
+++ b/examples/stm32/nucleo-f429zi-make-freertos-builtin/main.c
@@ -7,11 +7,12 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-cube-baremetal-builtin/Core/Src/main.c b/examples/stm32/nucleo-f746zg-cube-baremetal-builtin/Core/Src/main.c
index f086b785..4c48e5b6 100644
--- a/examples/stm32/nucleo-f746zg-cube-baremetal-builtin/Core/Src/main.c
+++ b/examples/stm32/nucleo-f746zg-cube-baremetal-builtin/Core/Src/main.c
@@ -90,13 +90,14 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return (uint64_t)HAL_GetTick();     // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-cube-freertos-builtin/Core/Src/main.c b/examples/stm32/nucleo-f746zg-cube-freertos-builtin/Core/Src/main.c
index 4a538d50..edc9028e 100644
--- a/examples/stm32/nucleo-f746zg-cube-freertos-builtin/Core/Src/main.c
+++ b/examples/stm32/nucleo-f746zg-cube-freertos-builtin/Core/Src/main.c
@@ -104,13 +104,14 @@ void server(void *argument);
 
 /* Private user code ---------------------------------------------------------*/
 /* USER CODE BEGIN 0 */
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Src/main.c b/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Src/main.c
index 45878ddf..112d66cf 100644
--- a/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Src/main.c
+++ b/examples/stm32/nucleo-f746zg-cube-freertos-lwip/Core/Src/main.c
@@ -71,13 +71,14 @@ void blinker(void const * argument);
 
 /* Private user code ---------------------------------------------------------*/
 /* USER CODE BEGIN 0 */
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 /* USER CODE END 0 */
diff --git a/examples/stm32/nucleo-f746zg-keil-baremetal/main.c b/examples/stm32/nucleo-f746zg-keil-baremetal/main.c
index b4cc5b30..612fbf6d 100644
--- a/examples/stm32/nucleo-f746zg-keil-baremetal/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-baremetal/main.c
@@ -12,13 +12,14 @@ uint64_t mg_millis(void) {          // Let Mongoose use our uptime function
   return (uint64_t) HAL_GetTick();  // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos-lwip/main.c b/examples/stm32/nucleo-f746zg-keil-freertos-lwip/main.c
index c1351648..fcaf0b61 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos-lwip/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-freertos-lwip/main.c
@@ -16,18 +16,19 @@
 extern void xPortSysTickHandler(void);
 void SysTick_Handler (void) {
   HAL_IncTick();
-  // xPortSysTickHandler() must be called after vTaskStartScheduler() and mx_init() takes longer than 1ms 
+  // xPortSysTickHandler() must be called after vTaskStartScheduler() and mx_init() takes longer than 1ms
   if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED)
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void server(void *args) {
@@ -74,14 +75,14 @@ static void netw_init (struct netif *netif) {
 
 static struct netif s_netif;
 
-static void app_main (void *args) { 
+static void app_main (void *args) {
   netw_init(&s_netif);
   xTaskCreate(netw, "netw", 128, &s_netif, configMAX_PRIORITIES - 1, NULL);  // Create the Ethernet link/rx thread
   MG_INFO(("Waiting for IP..."));
   while(ip4_addr_isany_val(*netif_ip4_addr(&s_netif)))
     vTaskDelay(pdMS_TO_TICKS(200));
   MG_INFO(("READY, IP: %s", ip4addr_ntoa(netif_ip4_addr(&s_netif))));
-  
+
   xTaskCreate(server, "server", 2048, 0, configMAX_PRIORITIES - 1, NULL);
   vTaskDelete(NULL);
   (void)args;
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos-tcp/main.c b/examples/stm32/nucleo-f746zg-keil-freertos-tcp/main.c
index e54522ce..130acb07 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos-tcp/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-freertos-tcp/main.c
@@ -13,17 +13,18 @@ extern RNG_HandleTypeDef hrng;
 extern void xPortSysTickHandler(void);
 void SysTick_Handler (void) {
   HAL_IncTick();
-  // xPortSysTickHandler() must be called after vTaskStartScheduler() and mx_init() takes longer than 1ms 
+  // xPortSysTickHandler() must be called after vTaskStartScheduler() and mx_init() takes longer than 1ms
   if (xTaskGetSchedulerState() != taskSCHEDULER_NOT_STARTED)
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void server(void *args) {
@@ -70,7 +71,7 @@ int main(void) {
 
   uint8_t macaddr[6] = GENERATE_LOCALLY_ADMINISTERED_MAC();
   // required for fallback if DHCP fails
-  static const uint8_t ipaddr[4] = {192, 168, 0, 77};	
+  static const uint8_t ipaddr[4] = {192, 168, 0, 77};
   static const uint8_t netmask[4] = {255, 255, 255, 0};
   static const uint8_t dnsaddr[4] = {8, 8, 8, 8};
   static const uint8_t gwaddr[4] = {192, 168, 0, 1};
@@ -98,7 +99,7 @@ void HAL_ETH_MspInit(ETH_HandleTypeDef *heth) {
 uint32_t ulApplicationGetNextSequenceNumber(uint32_t a, uint16_t b, uint32_t c,
                                             uint16_t d) {
   (void) a, (void) b, (void) c, (void) d;
-  uint32_t x;  
+  uint32_t x;
   HAL_RNG_GenerateRandomNumber(&hrng, &x);
   return x;
 }
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos/main.c b/examples/stm32/nucleo-f746zg-keil-freertos/main.c
index e6617060..fb9e7443 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-freertos/main.c
@@ -17,13 +17,14 @@ void SysTick_Handler(void) {
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/main.c b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/main.c
index 980c6c01..40199ee4 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2-lwip/main.c
@@ -5,7 +5,7 @@
 #include "mongoose.h"
 #include "main.h"
 #include "net.h"
-#include "cmsis_os2.h" 
+#include "cmsis_os2.h"
 #include "ethernetif.h"
 #include "lwip/dhcp.h"
 #include "lwip/netif.h"
@@ -14,13 +14,14 @@
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void server(void *args) {
@@ -67,14 +68,14 @@ static void netw_init (struct netif *netif) {
 
 static struct netif s_netif;
 
-static void app_main (void *args) { 
+static void app_main (void *args) {
   netw_init(&s_netif);
   osThreadNew(netw, &s_netif, NULL);  // Create the Ethernet link/rx thread with a default stack size
   MG_INFO(("Waiting for IP..."));
   while(ip4_addr_isany_val(*netif_ip4_addr(&s_netif)))
     osDelay((osKernelGetTickFreq() * 200U) / 1000U);
   MG_INFO(("READY, IP: %s", ip4addr_ntoa(netif_ip4_addr(&s_netif))));
-  
+
   const osThreadAttr_t server_attr = {
     .stack_size = 8192                            // Create the server thread with a stack size of 8KB
   };
@@ -94,7 +95,6 @@ int main(void) {
   osKernelInitialize();                 // Initialize CMSIS-RTOS
   osThreadNew(blinker, NULL, NULL);  // Create the blinker thread with a default stack size
   osThreadNew(app_main, NULL, NULL);  // Create the thread that will start networking, use a default stack size
-  osKernelStart();  // This blocks     
+  osKernelStart();  // This blocks
   return 0;
 }
-
diff --git a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/main.c b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/main.c
index 9fc7e73f..148386e3 100644
--- a/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-freertos_cmsis2/main.c
@@ -9,13 +9,14 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx-mdk/main.c b/examples/stm32/nucleo-f746zg-keil-rtx-mdk/main.c
index 7f0bf6e0..e50435fb 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx-mdk/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-rtx-mdk/main.c
@@ -5,18 +5,19 @@
 #include "mongoose.h"
 #include "main.h"
 #include "net.h"
-#include "cmsis_os.h" 
+#include "cmsis_os.h"
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void server(const void *args) {
@@ -50,7 +51,7 @@ void netDHCP_Notify (uint32_t if_num, uint8_t option, const uint8_t *val, uint32
   (void)if_num, (void)val, (void)len;
 }
 
-static void app_main (const void *args) { 
+static void app_main (const void *args) {
   uint8_t ipaddr[NET_ADDR_IP4_LEN];
   char ip[40];
   netInitialize();
@@ -70,7 +71,7 @@ osThreadDef(blinker, osPriorityNormal, 1, 0); // Create the blinker thread with
 osThreadDef(app_main, osPriorityNormal, 1, 1024); // Create the thread that will start networking with a stack size of 1KB
 
 extern void mx_init(void);
- 
+
 int main(void) {		// this is not actually baremetal main() but the "main" thread
   osKernelInitialize();                 // Stop kernel
   mx_init();                // Setup clock and all peripherals configured in CubeMX
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx/main.c b/examples/stm32/nucleo-f746zg-keil-rtx/main.c
index 43edfa83..79a97d34 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-rtx/main.c
@@ -9,13 +9,14 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/main.c b/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/main.c
index 62103e58..5177dcb0 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-rtx5-lwip/main.c
@@ -5,7 +5,7 @@
 #include "mongoose.h"
 #include "main.h"
 #include "net.h"
-#include "cmsis_os2.h" 
+#include "cmsis_os2.h"
 #include "ethernetif.h"
 #include "lwip/dhcp.h"
 #include "lwip/netif.h"
@@ -14,13 +14,14 @@
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void server(void *args) {
@@ -67,14 +68,14 @@ static void netw_init (struct netif *netif) {
 
 static struct netif s_netif;
 
-__NO_RETURN static void app_main (void *args) { 
+__NO_RETURN static void app_main (void *args) {
   netw_init(&s_netif);
   osThreadNew(netw, &s_netif, NULL);  // Create the Ethernet link/rx thread with a default stack size
   MG_INFO(("Waiting for IP..."));
   while(ip4_addr_isany_val(*netif_ip4_addr(&s_netif)))
     osDelay((osKernelGetTickFreq() * 200U) / 1000U);
   MG_INFO(("READY, IP: %s", ip4addr_ntoa(netif_ip4_addr(&s_netif))));
-  
+
   const osThreadAttr_t server_attr = {
     .stack_size = 8192                            // Create the server thread with a stack size of 8KB
   };
@@ -95,7 +96,6 @@ int main(void) {
   osKernelInitialize();                 // Initialize CMSIS-RTOS
   osThreadNew(blinker, NULL, NULL);  // Create the blinker thread with a default stack size
   osThreadNew(app_main, NULL, NULL);  // Create the thread that will start networking, use a default stack size
-  osKernelStart();  // This blocks     
+  osKernelStart();  // This blocks
   return 0;
 }
-
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/main.c b/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/main.c
index 47a79360..bd6826d8 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-rtx5-mdk/main.c
@@ -5,18 +5,19 @@
 #include "mongoose.h"
 #include "main.h"
 #include "net.h"
-#include "cmsis_os2.h" 
+#include "cmsis_os2.h"
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void server(void *args) {
@@ -48,7 +49,7 @@ void netDHCP_Notify (uint32_t if_num, uint8_t option, const uint8_t *val, uint32
   (void)if_num, (void)val, (void)len;
 }
 
-__NO_RETURN static void app_main (void *args) { 
+__NO_RETURN static void app_main (void *args) {
   uint8_t ipaddr[NET_ADDR_IP4_LEN];
   char ip[40];
 
@@ -80,7 +81,6 @@ int main(void) {
   osKernelInitialize();                 // Initialize CMSIS-RTOS
   osThreadNew(blinker, NULL, NULL);  // Create the blinker thread with a default stack size
   s_am = osThreadNew(app_main, NULL, NULL);  // Create the thread that will start networking, use a default stack size
-  osKernelStart();  // This blocks     
+  osKernelStart();  // This blocks
   return 0;
 }
-
diff --git a/examples/stm32/nucleo-f746zg-keil-rtx5/main.c b/examples/stm32/nucleo-f746zg-keil-rtx5/main.c
index 81f0fe1c..cd2b2095 100644
--- a/examples/stm32/nucleo-f746zg-keil-rtx5/main.c
+++ b/examples/stm32/nucleo-f746zg-keil-rtx5/main.c
@@ -9,13 +9,14 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-make-baremetal-builtin-cmsis_driver/main.c b/examples/stm32/nucleo-f746zg-make-baremetal-builtin-cmsis_driver/main.c
index 2c8e5fcb..55b65d7c 100644
--- a/examples/stm32/nucleo-f746zg-make-baremetal-builtin-cmsis_driver/main.c
+++ b/examples/stm32/nucleo-f746zg-make-baremetal-builtin-cmsis_driver/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-make-baremetal-builtin-rndis/main.c b/examples/stm32/nucleo-f746zg-make-baremetal-builtin-rndis/main.c
index 4c7f689c..74cadc70 100644
--- a/examples/stm32/nucleo-f746zg-make-baremetal-builtin-rndis/main.c
+++ b/examples/stm32/nucleo-f746zg-make-baremetal-builtin-rndis/main.c
@@ -22,11 +22,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 bool tud_network_recv_cb(const uint8_t *buf, uint16_t len) {
@@ -80,7 +81,7 @@ int main(void) {
   gpio_output(LED);               // Setup blue LED
   uart_init(UART_DEBUG, 115200);  // Initialise debug printf
 
-  struct mg_mgr mgr;        // Initialise 
+  struct mg_mgr mgr;        // Initialise
   mg_mgr_init(&mgr);        // Mongoose event manager
   mg_log_set(MG_LL_DEBUG);  // Set log level
 
diff --git a/examples/stm32/nucleo-f746zg-make-baremetal-builtin/main.c b/examples/stm32/nucleo-f746zg-make-baremetal-builtin/main.c
index 25a2a76e..dc4fa7a4 100644
--- a/examples/stm32/nucleo-f746zg-make-baremetal-builtin/main.c
+++ b/examples/stm32/nucleo-f746zg-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-make-freertos-builtin/main.c b/examples/stm32/nucleo-f746zg-make-freertos-builtin/main.c
index 75798cef..58382cba 100644
--- a/examples/stm32/nucleo-f746zg-make-freertos-builtin/main.c
+++ b/examples/stm32/nucleo-f746zg-make-freertos-builtin/main.c
@@ -7,11 +7,12 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-f746zg-make-freertos-tcp/main.c b/examples/stm32/nucleo-f746zg-make-freertos-tcp/main.c
index b0e36be0..0ac40691 100644
--- a/examples/stm32/nucleo-f746zg-make-freertos-tcp/main.c
+++ b/examples/stm32/nucleo-f746zg-make-freertos-tcp/main.c
@@ -23,11 +23,12 @@ void SysTick_Handler(void) {
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void ethernet_init(void) {
diff --git a/examples/stm32/nucleo-g031-make-baremetal-builtin/main.c b/examples/stm32/nucleo-g031-make-baremetal-builtin/main.c
index ec4ba68b..08d4810e 100644
--- a/examples/stm32/nucleo-g031-make-baremetal-builtin/main.c
+++ b/examples/stm32/nucleo-g031-make-baremetal-builtin/main.c
@@ -23,11 +23,12 @@ void SysTick_Handler(void) {       // SyStick IRQ handler, triggered every 1ms
   s_ticks++;
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
diff --git a/examples/stm32/nucleo-h563zi-make-baremetal-builtin/main.c b/examples/stm32/nucleo-h563zi-make-baremetal-builtin/main.c
index b60d1ce9..803f448c 100644
--- a/examples/stm32/nucleo-h563zi-make-baremetal-builtin/main.c
+++ b/examples/stm32/nucleo-h563zi-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-h563zi-make-freertos-builtin/main.c b/examples/stm32/nucleo-h563zi-make-freertos-builtin/main.c
index 272030a9..a5c217bb 100644
--- a/examples/stm32/nucleo-h563zi-make-freertos-builtin/main.c
+++ b/examples/stm32/nucleo-h563zi-make-freertos-builtin/main.c
@@ -7,11 +7,12 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-h723zg-make-baremetal-builtin/main.c b/examples/stm32/nucleo-h723zg-make-baremetal-builtin/main.c
index a0b00c3a..8ce71edc 100644
--- a/examples/stm32/nucleo-h723zg-make-baremetal-builtin/main.c
+++ b/examples/stm32/nucleo-h723zg-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 #ifdef MQTT_DASHBOARD
diff --git a/examples/stm32/nucleo-h723zg-make-freertos-builtin/main.c b/examples/stm32/nucleo-h723zg-make-freertos-builtin/main.c
index 7c261536..e363229f 100644
--- a/examples/stm32/nucleo-h723zg-make-freertos-builtin/main.c
+++ b/examples/stm32/nucleo-h723zg-make-freertos-builtin/main.c
@@ -15,11 +15,12 @@ void SysTick_Handler(void) {
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-h743zi-cube-baremetal-builtin/Core/Src/main.c b/examples/stm32/nucleo-h743zi-cube-baremetal-builtin/Core/Src/main.c
index 94f5b235..33e15a85 100644
--- a/examples/stm32/nucleo-h743zi-cube-baremetal-builtin/Core/Src/main.c
+++ b/examples/stm32/nucleo-h743zi-cube-baremetal-builtin/Core/Src/main.c
@@ -90,13 +90,14 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return (uint64_t)HAL_GetTick();     // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-h743zi-cube-freertos-builtin/Core/Src/main.c b/examples/stm32/nucleo-h743zi-cube-freertos-builtin/Core/Src/main.c
index e63defcc..1fa028eb 100644
--- a/examples/stm32/nucleo-h743zi-cube-freertos-builtin/Core/Src/main.c
+++ b/examples/stm32/nucleo-h743zi-cube-freertos-builtin/Core/Src/main.c
@@ -104,13 +104,14 @@ void server(void *argument);
 
 /* Private user code ---------------------------------------------------------*/
 /* USER CODE BEGIN 0 */
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   extern RNG_HandleTypeDef hrng;
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r;
     HAL_RNG_GenerateRandomNumber(&hrng, &r);
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-h743zi-make-baremetal-builtin/main.c b/examples/stm32/nucleo-h743zi-make-baremetal-builtin/main.c
index cd6a30a3..f9cb57db 100644
--- a/examples/stm32/nucleo-h743zi-make-baremetal-builtin/main.c
+++ b/examples/stm32/nucleo-h743zi-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/nucleo-h743zi-make-freertos-builtin/main.c b/examples/stm32/nucleo-h743zi-make-freertos-builtin/main.c
index 9706f30a..f01a1cb7 100644
--- a/examples/stm32/nucleo-h743zi-make-freertos-builtin/main.c
+++ b/examples/stm32/nucleo-h743zi-make-freertos-builtin/main.c
@@ -14,11 +14,12 @@ void SysTick_Handler(void) {
     xPortSysTickHandler();
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/stm32h573i-dk-make-baremetal-builtin/main.c b/examples/stm32/stm32h573i-dk-make-baremetal-builtin/main.c
index b60d1ce9..803f448c 100644
--- a/examples/stm32/stm32h573i-dk-make-baremetal-builtin/main.c
+++ b/examples/stm32/stm32h573i-dk-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/stm32h573i-dk-make-freertos-builtin/main.c b/examples/stm32/stm32h573i-dk-make-freertos-builtin/main.c
index 272030a9..a5c217bb 100644
--- a/examples/stm32/stm32h573i-dk-make-freertos-builtin/main.c
+++ b/examples/stm32/stm32h573i-dk-make-freertos-builtin/main.c
@@ -7,11 +7,12 @@
 
 #define BLINK_PERIOD_MS 1000  // LED blinking period in millis
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/stm32/stm32h747i-disco-make-baremetal-builtin/main.c b/examples/stm32/stm32h747i-disco-make-baremetal-builtin/main.c
index 2f008f4c..4b208805 100644
--- a/examples/stm32/stm32h747i-disco-make-baremetal-builtin/main.c
+++ b/examples/stm32/stm32h747i-disco-make-baremetal-builtin/main.c
@@ -16,11 +16,12 @@ uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
   return s_ticks;           // Return number of milliseconds since boot
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 static void timer_fn(void *arg) {
diff --git a/examples/wch/ch32v307-make-baremetal-builtin/hal.c b/examples/wch/ch32v307-make-baremetal-builtin/hal.c
index fa4e227a..1b82ab72 100644
--- a/examples/wch/ch32v307-make-baremetal-builtin/hal.c
+++ b/examples/wch/ch32v307-make-baremetal-builtin/hal.c
@@ -26,11 +26,12 @@ __attribute__((interrupt())) void SysTick_Handler(void) {
   SysTick->SR = 0;
 }
 
-void mg_random(void *buf, size_t len) {  // Use on-board RNG
+bool mg_random(void *buf, size_t len) {  // Use on-board RNG
   for (size_t n = 0; n < len; n += sizeof(uint32_t)) {
     uint32_t r = rng_read();
     memcpy((char *) buf + n, &r, n + sizeof(r) > len ? len - n : sizeof(r));
   }
+  return true;
 }
 
 uint64_t mg_millis(void) {  // Let Mongoose use our uptime function
diff --git a/mongoose.c b/mongoose.c
index cf0eb4be..de50ea3d 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -10066,7 +10066,7 @@ static void mg_tls_server_send_hello(struct mg_connection *c) {
   // calculate keyshare
   uint8_t x25519_pub[X25519_BYTES];
   uint8_t x25519_prv[X25519_BYTES];
-  mg_random(x25519_prv, sizeof(x25519_prv));
+  if (!mg_random(x25519_prv, sizeof(x25519_prv))) mg_error(c, "RNG"); 
   mg_tls_x25519(x25519_pub, x25519_prv, X25519_BASE_POINT, 1);
   mg_tls_x25519(tls->x25519_sec, x25519_prv, tls->x25519_cli, 1);
   mg_tls_hexdump("s x25519 sec", tls->x25519_sec, sizeof(tls->x25519_sec));
@@ -10292,12 +10292,12 @@ static void mg_tls_client_send_hello(struct mg_connection *c) {
   }
 
   // calculate keyshare
-  mg_random(tls->x25519_cli, sizeof(tls->x25519_cli));
+  if (!mg_random(tls->x25519_cli, sizeof(tls->x25519_cli))) mg_error(c, "RNG");
   mg_tls_x25519(x25519_pub, tls->x25519_cli, X25519_BASE_POINT, 1);
 
   // fill in the gaps: random + session ID + keyshare
-  mg_random(tls->session_id, sizeof(tls->session_id));
-  mg_random(tls->random, sizeof(tls->random));
+  if (!mg_random(tls->session_id, sizeof(tls->session_id))) mg_error(c, "RNG");
+  if (!mg_random(tls->random, sizeof(tls->random))) mg_error(c, "RNG");
   memmove(msg_client_hello + 11, tls->random, sizeof(tls->random));
   memmove(msg_client_hello + 44, tls->session_id, sizeof(tls->session_id));
   memmove(msg_client_hello + 94, x25519_pub, sizeof(x25519_pub));
@@ -16337,6 +16337,7 @@ struct mg_str mg_url_pass(const char *url) {
 #endif
 
 
+
 // Not using memset for zeroing memory, cause it can be dropped by compiler
 // See https://github.com/cesanta/mongoose/pull/1265
 void mg_bzero(volatile unsigned char *buf, size_t len) {
@@ -16347,22 +16348,50 @@ void mg_bzero(volatile unsigned char *buf, size_t len) {
 
 #if MG_ENABLE_CUSTOM_RANDOM
 #else
-void mg_random(void *buf, size_t len) {
-  bool done = false;
+bool mg_random(void *buf, size_t len) {
+  bool success = false;
   unsigned char *p = (unsigned char *) buf;
 #if MG_ARCH == MG_ARCH_ESP32
   while (len--) *p++ = (unsigned char) (esp_random() & 255);
-  done = true;
+  success = true;
 #elif MG_ARCH == MG_ARCH_WIN32
+  static bool initialised = false;
+#if defined(_MSC_VER) && _MSC_VER < 1700
+  static HCRYPTPROV hProv;
+  // CryptGenRandom() implementation earlier than 2008 is weak, see
+  // https://en.wikipedia.org/wiki/CryptGenRandom
+  if (initialised == false) {
+    initialised = CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL,
+                                      CRYPT_VERIFYCONTEXT);
+  }
+  if (initialised == true) {
+    success = CryptGenRandom(hProv, len, p);
+  }
+#else
+  // BCrypt is a "new generation" strong crypto API, so try it first
+  static BCRYPT_ALG_HANDLE hProv;
+  if (initialised == false &&
+      BCryptOpenAlgorithmProvider(&hProv, BCRYPT_RNG_ALGORITHM, NULL, 0) == 0) {
+    initialised = true;
+  }
+  if (initialised == true) {
+    success = BCryptGenRandom(hProv, p, (ULONG) len, 0) == 0;
+  }
+#endif
+
 #elif MG_ARCH == MG_ARCH_UNIX
   FILE *fp = fopen("/dev/urandom", "rb");
   if (fp != NULL) {
-    if (fread(buf, 1, len, fp) == len) done = true;
+    if (fread(buf, 1, len, fp) == len) success = true;
     fclose(fp);
   }
 #endif
   // If everything above did not work, fallback to a pseudo random generator
-  while (!done && len--) *p++ = (unsigned char) (rand() & 255);
+  if (success == false) {
+    MG_ERROR(("Weak RNG: using rand()"));
+    while (len--) *p++ = (unsigned char) (rand() & 255);
+  }
+  return success;
 }
 #endif
 
diff --git a/mongoose.h b/mongoose.h
index 1cc3d837..3489fe49 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -443,6 +443,20 @@ typedef enum { false = 0, true = 1 } bool;
 #include <winerror.h>
 #include <winsock2.h>
 
+// For mg_random()
+#if defined(_MSC_VER) && _MSC_VER < 1700
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x400  // Let vc98 pick up wincrypt.h
+#endif
+#include <wincrypt.h>
+#pragma comment(lib, "advapi32.lib")
+#else
+#include <bcrypt.h>
+#if defined(_MSC_VER) 
+#pragma comment(lib, "bcrypt.lib")
+#endif
+#endif
+
 // Protect from calls like std::snprintf in app code
 // See https://github.com/cesanta/mongoose/issues/1047
 #ifndef __cplusplus
@@ -487,12 +501,12 @@ typedef int socklen_t;
   (((errcode) < 0) && (WSAGetLastError() == WSAECONNRESET))
 
 #define realpath(a, b) _fullpath((b), (a), MG_PATH_MAX)
-#define sleep(x) Sleep((x) *1000)
+#define sleep(x) Sleep((x) * 1000)
 #define mkdir(a, b) _mkdir(a)
 #define timegm(x) _mkgmtime(x)
 
 #ifndef S_ISDIR
-#define S_ISDIR(x) (((x) &_S_IFMT) == _S_IFDIR)
+#define S_ISDIR(x) (((x) & _S_IFMT) == _S_IFDIR)
 #endif
 
 #ifndef MG_ENABLE_DIRLIST
@@ -1056,7 +1070,7 @@ struct mg_str mg_unpacked(const char *path);  // Packed file as mg_str
 #endif
 
 void mg_bzero(volatile unsigned char *buf, size_t len);
-void mg_random(void *buf, size_t len);
+bool mg_random(void *buf, size_t len);
 char *mg_random_str(char *buf, size_t len);
 uint16_t mg_ntohs(uint16_t net);
 uint32_t mg_ntohl(uint32_t net);
diff --git a/src/arch_win32.h b/src/arch_win32.h
index b0ab1b69..c31310f3 100644
--- a/src/arch_win32.h
+++ b/src/arch_win32.h
@@ -50,6 +50,20 @@ typedef enum { false = 0, true = 1 } bool;
 #include <winerror.h>
 #include <winsock2.h>
 
+// For mg_random()
+#if defined(_MSC_VER) && _MSC_VER < 1700
+#ifndef _WIN32_WINNT
+#define _WIN32_WINNT 0x400  // Let vc98 pick up wincrypt.h
+#endif
+#include <wincrypt.h>
+#pragma comment(lib, "advapi32.lib")
+#else
+#include <bcrypt.h>
+#if defined(_MSC_VER)
+#pragma comment(lib, "bcrypt.lib")
+#endif
+#endif
+
 // Protect from calls like std::snprintf in app code
 // See https://github.com/cesanta/mongoose/issues/1047
 #ifndef __cplusplus
@@ -94,12 +108,12 @@ typedef int socklen_t;
   (((errcode) < 0) && (WSAGetLastError() == WSAECONNRESET))
 
 #define realpath(a, b) _fullpath((b), (a), MG_PATH_MAX)
-#define sleep(x) Sleep((x) *1000)
+#define sleep(x) Sleep((x) * 1000)
 #define mkdir(a, b) _mkdir(a)
 #define timegm(x) _mkgmtime(x)
 
 #ifndef S_ISDIR
-#define S_ISDIR(x) (((x) &_S_IFMT) == _S_IFDIR)
+#define S_ISDIR(x) (((x) & _S_IFMT) == _S_IFDIR)
 #endif
 
 #ifndef MG_ENABLE_DIRLIST
diff --git a/src/tls_builtin.c b/src/tls_builtin.c
index d96d4b39..9c4c585d 100644
--- a/src/tls_builtin.c
+++ b/src/tls_builtin.c
@@ -623,7 +623,7 @@ static void mg_tls_server_send_hello(struct mg_connection *c) {
   // calculate keyshare
   uint8_t x25519_pub[X25519_BYTES];
   uint8_t x25519_prv[X25519_BYTES];
-  mg_random(x25519_prv, sizeof(x25519_prv));
+  if (!mg_random(x25519_prv, sizeof(x25519_prv))) mg_error(c, "RNG"); 
   mg_tls_x25519(x25519_pub, x25519_prv, X25519_BASE_POINT, 1);
   mg_tls_x25519(tls->x25519_sec, x25519_prv, tls->x25519_cli, 1);
   mg_tls_hexdump("s x25519 sec", tls->x25519_sec, sizeof(tls->x25519_sec));
@@ -849,12 +849,12 @@ static void mg_tls_client_send_hello(struct mg_connection *c) {
   }
 
   // calculate keyshare
-  mg_random(tls->x25519_cli, sizeof(tls->x25519_cli));
+  if (!mg_random(tls->x25519_cli, sizeof(tls->x25519_cli))) mg_error(c, "RNG");
   mg_tls_x25519(x25519_pub, tls->x25519_cli, X25519_BASE_POINT, 1);
 
   // fill in the gaps: random + session ID + keyshare
-  mg_random(tls->session_id, sizeof(tls->session_id));
-  mg_random(tls->random, sizeof(tls->random));
+  if (!mg_random(tls->session_id, sizeof(tls->session_id))) mg_error(c, "RNG");
+  if (!mg_random(tls->random, sizeof(tls->random))) mg_error(c, "RNG");
   memmove(msg_client_hello + 11, tls->random, sizeof(tls->random));
   memmove(msg_client_hello + 44, tls->session_id, sizeof(tls->session_id));
   memmove(msg_client_hello + 94, x25519_pub, sizeof(x25519_pub));
diff --git a/src/util.c b/src/util.c
index 332ce93b..345fa0f5 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,3 +1,4 @@
+#include "log.h"
 #include "util.h"
 
 // Not using memset for zeroing memory, cause it can be dropped by compiler
@@ -10,22 +11,50 @@ void mg_bzero(volatile unsigned char *buf, size_t len) {
 
 #if MG_ENABLE_CUSTOM_RANDOM
 #else
-void mg_random(void *buf, size_t len) {
-  bool done = false;
+bool mg_random(void *buf, size_t len) {
+  bool success = false;
   unsigned char *p = (unsigned char *) buf;
 #if MG_ARCH == MG_ARCH_ESP32
   while (len--) *p++ = (unsigned char) (esp_random() & 255);
-  done = true;
+  success = true;
 #elif MG_ARCH == MG_ARCH_WIN32
+  static bool initialised = false;
+#if defined(_MSC_VER) && _MSC_VER < 1700
+  static HCRYPTPROV hProv;
+  // CryptGenRandom() implementation earlier than 2008 is weak, see
+  // https://en.wikipedia.org/wiki/CryptGenRandom
+  if (initialised == false) {
+    initialised = CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL,
+                                      CRYPT_VERIFYCONTEXT);
+  }
+  if (initialised == true) {
+    success = CryptGenRandom(hProv, len, p);
+  }
+#else
+  // BCrypt is a "new generation" strong crypto API, so try it first
+  static BCRYPT_ALG_HANDLE hProv;
+  if (initialised == false &&
+      BCryptOpenAlgorithmProvider(&hProv, BCRYPT_RNG_ALGORITHM, NULL, 0) == 0) {
+    initialised = true;
+  }
+  if (initialised == true) {
+    success = BCryptGenRandom(hProv, p, (ULONG) len, 0) == 0;
+  }
+#endif
+
 #elif MG_ARCH == MG_ARCH_UNIX
   FILE *fp = fopen("/dev/urandom", "rb");
   if (fp != NULL) {
-    if (fread(buf, 1, len, fp) == len) done = true;
+    if (fread(buf, 1, len, fp) == len) success = true;
     fclose(fp);
   }
 #endif
   // If everything above did not work, fallback to a pseudo random generator
-  while (!done && len--) *p++ = (unsigned char) (rand() & 255);
+  if (success == false) {
+    MG_ERROR(("Weak RNG: using rand()"));
+    while (len--) *p++ = (unsigned char) (rand() & 255);
+  }
+  return success;
 }
 #endif
 
diff --git a/src/util.h b/src/util.h
index 58f3b5ab..78405946 100644
--- a/src/util.h
+++ b/src/util.h
@@ -12,7 +12,7 @@
 #endif
 
 void mg_bzero(volatile unsigned char *buf, size_t len);
-void mg_random(void *buf, size_t len);
+bool mg_random(void *buf, size_t len);
 char *mg_random_str(char *buf, size_t len);
 uint16_t mg_ntohs(uint16_t net);
 uint32_t mg_ntohl(uint32_t net);
diff --git a/test/Makefile b/test/Makefile
index 4926da7f..def1a243 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -6,9 +6,10 @@ OPTS ?= -O3 -g3
 INCS ?= -Isrc -I.
 SSL ?=
 CWD ?= $(realpath $(CURDIR))
+ROOT_DIR = $(realpath $(CWD)/..)
 ENV ?=  -e Tmp=. -e WINEDEBUG=-all
 DOCKER_BIN ?= docker
-DOCKER ?= $(DOCKER_BIN) run --platform linux/amd64 --rm $(ENV) -v $(CWD)/..:$(CWD)/.. -w $(CWD)
+DOCKER ?= $(DOCKER_BIN) run --platform linux/amd64 --rm $(ENV) -v $(ROOT_DIR):$(ROOT_DIR) -w $(CWD)
 VCFLAGS = /nologo /W3 /O2 /MD /I. $(DEFS) $(TFLAGS)
 IPV6 ?= 1
 ASAN ?= -fsanitize=address,undefined,alignment -fno-sanitize-recover=all -fno-omit-frame-pointer -fno-common
@@ -166,23 +167,23 @@ riscv: mongoose.h $(SRCS)
 	$(DOCKER) mdashnet/riscv riscv-none-elf-gcc -march=rv32imc -mabi=ilp32 $(SRCS) $(OPTS) $(WARN) $(INCS) $(DEFS) $(TFLAGS) -o unit_test
 
 vc98: Makefile mongoose.h $(SRCS)
-	$(DOCKER) mdashnet/vc98 wine cl $(SRCS) $(VCFLAGS) ws2_32.lib /Fe$@.exe
+	$(DOCKER) mdashnet/vc98 wine cl $(SRCS) $(VCFLAGS) /Fe$@.exe
 	$(DOCKER) mdashnet/vc98 wine $@.exe
 
 vc17: Makefile mongoose.h $(SRCS)
-	$(DOCKER) mdashnet/vc17 wine64 cl $(SRCS) $(VCFLAGS) ws2_32.lib /Fe$@.exe
+	$(DOCKER) mdashnet/vc17 wine64 cl $(SRCS) $(VCFLAGS) /Fe$@.exe
 	$(DOCKER) mdashnet/vc17 wine64 $@.exe
 
 vc22: Makefile mongoose.h $(SRCS)
-	$(DOCKER) mdashnet/vc22 wine64 cl $(SRCS) $(VCFLAGS) ws2_32.lib /Fe$@.exe
+	$(DOCKER) mdashnet/vc22 wine64 cl $(SRCS) $(VCFLAGS) /Fe$@.exe
 	$(DOCKER) mdashnet/vc22 wine64 $@.exe
 
 mingw: Makefile mongoose.h $(SRCS)
-	$(DOCKER) mdashnet/mingw x86_64-w64-mingw32-gcc $(SRCS) -W -Wall -Werror -I. $(DEFS) -lwsock32 -o $@.exe
+	$(DOCKER) mdashnet/mingw x86_64-w64-mingw32-gcc $(SRCS) -W -Wall -Werror -I. $(DEFS) -lwsock32 -lbcrypt -o $@.exe
 	$(DOCKER) mdashnet/mingw wine64 $@.exe
 
 mingw++: Makefile mongoose.h $(SRCS)
-	$(DOCKER) mdashnet/mingw x86_64-w64-mingw32-g++ $(SRCS) -W -Wall -Werror -I. $(DEFS) -lwsock32 -o $@.exe
+	$(DOCKER) mdashnet/mingw x86_64-w64-mingw32-g++ $(SRCS) -W -Wall -Werror -I. $(DEFS) -lwsock32 -lbcrypt -o $@.exe
 
 linux-libs: CFLAGS += -fPIC
 linux-libs: LDFLAGS += -Wl,-soname,libmongoose.so.$(VERSION)
diff --git a/tutorials/http/http-server/Makefile b/tutorials/http/http-server/Makefile
index 43098952..b0a6b340 100644
--- a/tutorials/http/http-server/Makefile
+++ b/tutorials/http/http-server/Makefile
@@ -3,7 +3,7 @@ DELETE = rm -rf                   # Command to remove files
 OUT ?= -o $(PROG)                 # Compiler argument for output file
 SOURCES = main.c mongoose.c       # Source code files
 CFLAGS = -W -Wall -Wextra -g -I.  # Build options
-CFLAGS += -fsanitize=address,undefined,alignment
+#CFLAGS += -fsanitize=address,undefined,alignment
 
 # Mongoose build options. See https://mongoose.ws/documentation/#build-options
 CFLAGS_MONGOOSE += -DMG_HTTP_DIRLIST_TIME_FMT="%Y/%m/%d %H:%M:%S"
@@ -13,7 +13,7 @@ CFLAGS_MONGOOSE += -DMG_TLS=MG_TLS_BUILTIN
 ifeq ($(OS),Windows_NT)   # Windows settings. Assume MinGW compiler. To use VC: make CC=cl CFLAGS=/MD OUT=/Feprog.exe
   PROG ?= example.exe           # Use .exe suffix for the binary
   CC = gcc                      # Use MinGW gcc compiler
-  CFLAGS += -lws2_32            # Link against Winsock library
+  CFLAGS += -lws2_32 -lbcrypt   # Link against Winsock library
   DELETE = cmd /C del /Q /F /S  # Command prompt command to delete files
   OUT ?= -o $(PROG)             # Build output
 endif
@@ -24,5 +24,8 @@ all: $(PROG)              # Default target. Build and run program
 $(PROG): $(SOURCES)       # Build program from sources
 	$(CC) $(SOURCES) $(CFLAGS) $(CFLAGS_MONGOOSE) $(CFLAGS_EXTRA) $(OUT)
 
+vc98:
+	cl $(SOURCES) -DMG_ENABLE_SSI=1 -DMG_TLS=MG_TLS_BUILTIN
+
 clean:                    # Cleanup. Delete built program and all build artifacts
 	$(DELETE) $(PROG) *.o *.obj *.exe *.dSYM