From 1df8bc0dfe7806fa45a91fe1c8e1aa92b042f520 Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@users.noreply.github.com>
Date: Mon, 27 Feb 2023 10:22:52 -0300
Subject: [PATCH 1/7] Update test.yml

Fix embedded matrix workflow not signalling changes and not running
---
 .github/workflows/test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index b9ac4190..756f00e3 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -201,7 +201,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
         with: { fetch-depth: 2 }
-      - run: if ./test/match_changed_files.sh '^src|^examples/${{ matrix.example.path }}'; then sudo apt -y update ; sudo apt -y install gcc-arm-none-eabi ; fi
+      - run: if ./test/match_changed_files.sh '^src|^examples/${{ matrix.example.path }}'; then echo GO=1 >> $GITHUB_ENV ; fi
       - if: ${{ env.GO == 1 }}
         run: sudo apt -y update ; sudo apt -y install gcc-arm-none-eabi
       - if: ${{ env.GO == 1 }}

From 4e7584167b16be0ff12baedab082a03fc1b08df7 Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@cesanta.com>
Date: Mon, 27 Feb 2023 10:54:32 -0300
Subject: [PATCH 2/7] force check and failures

---
 examples/stm32/nucleo-f429zi-rndis/main.c | 2 +-
 src/tcpip/tcpip.h                         | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/examples/stm32/nucleo-f429zi-rndis/main.c b/examples/stm32/nucleo-f429zi-rndis/main.c
index 7777b5d5..ba6dd324 100644
--- a/examples/stm32/nucleo-f429zi-rndis/main.c
+++ b/examples/stm32/nucleo-f429zi-rndis/main.c
@@ -95,7 +95,7 @@ int main(void) {
                             .mask = mg_htonl(MG_U32(255, 255, 255, 0)),
                             .enable_dhcp_server = true,
                             .driver = &driver,
-                            .queue.len = 4096};
+                            .recv_queue.size = 4096};
   s_ifp = &mif;
   mg_tcpip_init(&mgr, &mif);
   mg_timer_add(&mgr, 500, MG_TIMER_REPEAT, blink_cb, &mgr);
diff --git a/src/tcpip/tcpip.h b/src/tcpip/tcpip.h
index 8c042619..371faed4 100644
--- a/src/tcpip/tcpip.h
+++ b/src/tcpip/tcpip.h
@@ -64,8 +64,8 @@ struct mg_tcpip_spi {
 
 #if MG_ENABLE_TCPIP
 #if !defined(MG_ENABLE_DRIVER_STM32H) && !defined(MG_ENABLE_DRIVER_TM4C)
-#define MG_ENABLE_DRIVER_STM32 1
+  #define MG_ENABLE_DRIVER_STM32 1
 #else
-#define MG_ENABLE_DRIVER_STM32 0
+  #define MG_ENABLE_DRIVER_STM32 0
 #endif
 #endif

From 520507afd965ccef83f83ed2e96e8a65291af733 Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@cesanta.com>
Date: Mon, 27 Feb 2023 11:28:42 -0300
Subject: [PATCH 3/7] unbreak RNDIS examples

---
 examples/rp2040/pico-rmii/driver_rp2040_rmii.c | 3 +--
 examples/rp2040/pico-rndis-dashboard/main.c    | 4 ++--
 examples/stm32/nucleo-f429zi-rndis/main.c      | 3 +--
 examples/stm32/nucleo-f746zg-rndis/main.c      | 5 ++---
 4 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/examples/rp2040/pico-rmii/driver_rp2040_rmii.c b/examples/rp2040/pico-rmii/driver_rp2040_rmii.c
index 5a244d24..b61bd450 100644
--- a/examples/rp2040/pico-rmii/driver_rp2040_rmii.c
+++ b/examples/rp2040/pico-rmii/driver_rp2040_rmii.c
@@ -256,7 +256,6 @@ static bool mg_tcpip_driver_rp2040_rmii_init(struct mg_tcpip_if *ifp) {
       (struct mg_tcpip_driver_rp2040_rmii_data *) ifp->driver_data;
   uint rx_sm_addr, tx_sm_addr;
   s_ifp = ifp;
-  if (ifp->queue.len == 0) ifp->queue.len = 8192;
   rx_sm_addr = pio_add_program(pio0, &rmii_rx_program);
   tx_sm_addr = pio_add_program(pio0, &rmii_tx_program);
   smi_wr_addr = pio_add_program(pio0, &smi_wr_program);
@@ -338,7 +337,7 @@ static void rx_irq(void) {
 }
 
 static size_t mg_tcpip_driver_rp2040_rmii_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
-  size_t len = mg_tcpip_qread(buf, ifp);
+  size_t len = 0; // mg_tcpip_qread(buf, ifp);
   if (len == 0) return 0;
   len -= 4;                           // exclude CRC from frame length
   uint32_t crc = crc_calc(buf, len);  // calculate CRC and compare
diff --git a/examples/rp2040/pico-rndis-dashboard/main.c b/examples/rp2040/pico-rndis-dashboard/main.c
index 07846396..1ebd3292 100644
--- a/examples/rp2040/pico-rndis-dashboard/main.c
+++ b/examples/rp2040/pico-rndis-dashboard/main.c
@@ -56,13 +56,13 @@ int main(void) {
   mg_mgr_init(&mgr);  // and attach it to the MIP interface
   mg_timer_add(&mgr, 500, MG_TIMER_REPEAT, blink_cb, &mgr);
 
-  struct mg_tcpip_driver driver = {.tx = usb_tx, .rx = mg_tcpip_driver_rx, .up = usb_up};
+  struct mg_tcpip_driver driver = {.tx = usb_tx, .up = usb_up};
   struct mg_tcpip_if mif = {.mac = {2, 0, 1, 2, 3, 0x77},
                        .ip = mg_htonl(MG_U32(192, 168, 3, 1)),
                        .mask = mg_htonl(MG_U32(255, 255, 255, 0)),
                        .enable_dhcp_server = true,
                        .driver = &driver,
-                       .queue.len = 4096};
+                       .recv_queue.size = 4096};
   s_ifp = &mif;
   mg_tcpip_init(&mgr, &mif);
   tusb_init();
diff --git a/examples/stm32/nucleo-f429zi-rndis/main.c b/examples/stm32/nucleo-f429zi-rndis/main.c
index ba6dd324..b4bbe32e 100644
--- a/examples/stm32/nucleo-f429zi-rndis/main.c
+++ b/examples/stm32/nucleo-f429zi-rndis/main.c
@@ -88,8 +88,7 @@ int main(void) {
 
 
   MG_INFO(("Init TCP/IP stack ..."));
-  struct mg_tcpip_driver driver = {
-      .tx = usb_tx, .rx = mg_tcpip_driver_rx, .up = usb_up};
+  struct mg_tcpip_driver driver = {.tx = usb_tx, .up = usb_up};
   struct mg_tcpip_if mif = {.mac = GENERATE_LOCALLY_ADMINISTERED_MAC(),
                             .ip = mg_htonl(MG_U32(192, 168, 3, 1)),
                             .mask = mg_htonl(MG_U32(255, 255, 255, 0)),
diff --git a/examples/stm32/nucleo-f746zg-rndis/main.c b/examples/stm32/nucleo-f746zg-rndis/main.c
index 8aee5af3..6bf7ff83 100644
--- a/examples/stm32/nucleo-f746zg-rndis/main.c
+++ b/examples/stm32/nucleo-f746zg-rndis/main.c
@@ -88,14 +88,13 @@ int main(void) {
 
 
   MG_INFO(("Init TCP/IP stack ..."));
-  struct mg_tcpip_driver driver = {
-      .tx = usb_tx, .rx = mg_tcpip_driver_rx, .up = usb_up};
+  struct mg_tcpip_driver driver = {.tx = usb_tx, .up = usb_up};
   struct mg_tcpip_if mif = {.mac = GENERATE_LOCALLY_ADMINISTERED_MAC(),
                             .ip = mg_htonl(MG_U32(192, 168, 3, 1)),
                             .mask = mg_htonl(MG_U32(255, 255, 255, 0)),
                             .enable_dhcp_server = true,
                             .driver = &driver,
-                            .queue.len = 4096};
+                            .recv_queue.size = 4096};
   s_ifp = &mif;
   mg_tcpip_init(&mgr, &mif);
   mg_timer_add(&mgr, 500, MG_TIMER_REPEAT, blink_cb, &mgr);

From bba361016d07f06ce17b2aecd632c05d056f96cc Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@cesanta.com>
Date: Mon, 27 Feb 2023 17:21:33 -0300
Subject: [PATCH 4/7] Update RMII ex, enhance MIP

---
 .../rp2040/pico-rmii/driver_rp2040_rmii.c     | 59 +++++--------------
 examples/rp2040/pico-rmii/main.c              |  2 +
 mongoose.c                                    | 34 ++++++-----
 mongoose.h                                    | 15 +++--
 src/tcpip/tcpip.c                             | 22 +++----
 src/tcpip/tcpip.h                             | 19 +++---
 src/util.c                                    | 12 ++--
 7 files changed, 73 insertions(+), 90 deletions(-)

diff --git a/examples/rp2040/pico-rmii/driver_rp2040_rmii.c b/examples/rp2040/pico-rmii/driver_rp2040_rmii.c
index b61bd450..e77b81d1 100644
--- a/examples/rp2040/pico-rmii/driver_rp2040_rmii.c
+++ b/examples/rp2040/pico-rmii/driver_rp2040_rmii.c
@@ -29,21 +29,21 @@ static dma_channel_config dmacfg_tx;
 
 static uint8_t s_rxbuf[2][ETH_PKT_SIZE];  // ping-pong buffer
 static uint8_t s_txbuf[ETH_PKT_SIZE];
-static struct mg_tcpip_if *s_ifp;             // MIP interface
+static struct mg_tcpip_if *s_ifp;  // MIP interface
 
 #define rmii_tx_wrap_target 0
 #define rmii_tx_wrap 8
 
 static const uint16_t rmii_tx_program_instructions[] = {
     //     .wrap_target
-    0xe000, //  0: set    pins, 0         side 0     
-    0x80a0, //  1: pull   block           side 0     
-    0xe03d, //  2: set    x, 29           side 0     
-    0xf101, //  3: set    pins, 1         side 1 [1] 
-    0x1144, //  4: jmp    x--, 4          side 1 [1] 
-    0xf103, //  5: set    pins, 3         side 1 [1] 
-    0x7002, //  6: out    pins, 2         side 1     
-    0x10e6, //  7: jmp    !osre, 6        side 1     
+    0xe000,  //  0: set    pins, 0         side 0
+    0x80a0,  //  1: pull   block           side 0
+    0xe03d,  //  2: set    x, 29           side 0
+    0xf101,  //  3: set    pins, 1         side 1 [1]
+    0x1144,  //  4: jmp    x--, 4          side 1 [1]
+    0xf103,  //  5: set    pins, 3         side 1 [1]
+    0x7002,  //  6: out    pins, 2         side 1
+    0x10e6,  //  7: jmp    !osre, 6        side 1
              //     .wrap
 };
 
@@ -216,21 +216,6 @@ static inline void smi_rd_init(PIO pio, uint sm, uint addr, uint gpio) {
   pio_sm_init(pio, sm, addr, &c);
 }
 
-static inline uint32_t crc_calc(const uint8_t *data, int length) {
-  static const uint32_t crclut[16] = {
-      // table for polynomial 0xEDB88320 (reflected)
-      0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190, 0x6B6B51F4,
-      0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C,
-      0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C};
-  uint32_t crc = 0xFFFFFFFF;
-  while (--length >= 0) {
-    uint8_t byte = *data++;
-    crc = crclut[(crc ^ byte) & 0x0F] ^ (crc >> 4);
-    crc = crclut[(crc ^ (byte >> 4)) & 0x0F] ^ (crc >> 4);
-  }
-  return ~crc;
-}
-
 static void eth_write_phy(int addr, int reg, int val, uint8_t gpio) {
   uint16_t op = 0x5002 | (addr << 7) | (reg << 2);  // b0101aaaaarrrrr10
   smi_wr_init(pio0, SMITXSM, smi_wr_addr, gpio);
@@ -299,12 +284,12 @@ static bool mg_tcpip_driver_rp2040_rmii_init(struct mg_tcpip_if *ifp) {
 }
 
 static size_t mg_tcpip_driver_rp2040_rmii_tx(const void *buf, size_t len,
-                                 struct mg_tcpip_if *ifp) {
+                                             struct mg_tcpip_if *ifp) {
   dma_channel_wait_for_finish_blocking(dma_tx);
   memset(s_txbuf, 0, 60);  // pre-pad
   memcpy(s_txbuf, buf, len);
   if (len < 60) len = 60;                 // pad
-  uint32_t crc = crc_calc(s_txbuf, len);  // host is little-endian
+  uint32_t crc = mg_crc32(0, s_txbuf, len);  // host is little-endian
   memcpy(s_txbuf + len, (uint8_t *) &crc, 4);
   len += 4;
   sleep_us(10);  // enforce IFG in case software has been lightning fast...
@@ -324,31 +309,17 @@ static void rx_irq(void) {
       1;  // 2 buffers, switch to the available one as fast as possible
   size_t len = ETH_PKT_SIZE - hw->transfer_count;
   dma_channel_abort(dma_rx);
-  dma_channel_set_write_addr(dma_rx, s_rxbuf[rxno], true); // restart DMA
+  dma_channel_set_write_addr(dma_rx, s_rxbuf[rxno], true);  // restart DMA
   pio_interrupt_clear(pio0,
                       0);  // ACK PIO IRQ so the state machine resumes receiving
   // NOTE(scaprile) Here we could check addressing to avoid queuing frames not
-  // for us, or we can defer that for later as we do with CRC The max amount of
-  // time we can linger here is what it takes for the other buffer to fill
-  // (<8us) and that includes irq chaining
+  // for us. The max amount of time we can linger here is what it takes for the
+  // other buffer to fill (<8us) and that includes irq chaining
   if (len >= 64 && len <= ETH_PKT_SIZE)
     mg_tcpip_qwrite(s_rxbuf[s_rxno], len, s_ifp);
   s_rxno = rxno;
 }
 
-static size_t mg_tcpip_driver_rp2040_rmii_rx(void *buf, size_t buflen, struct mg_tcpip_if *ifp) {
-  size_t len = 0; // mg_tcpip_qread(buf, ifp);
-  if (len == 0) return 0;
-  len -= 4;                           // exclude CRC from frame length
-  uint32_t crc = crc_calc(buf, len);  // calculate CRC and compare
-  // NOTE(scaprile) Here we could check addressing to avoid delivering frames
-  // not for us, though MIP already does that (now ?)
-  if (memcmp(&((uint8_t *) buf)[len], &crc,
-             sizeof(crc)))  // host is little-endian
-    return 0;
-  return len;
-}
-
 static bool mg_tcpip_driver_rp2040_rmii_up(struct mg_tcpip_if *ifp) {
   struct mg_tcpip_driver_rp2040_rmii_data *d =
       (struct mg_tcpip_driver_rp2040_rmii_data *) ifp->driver_data;
@@ -360,6 +331,6 @@ static bool mg_tcpip_driver_rp2040_rmii_up(struct mg_tcpip_if *ifp) {
 struct mg_tcpip_driver mg_tcpip_driver_rp2040_rmii = {
     mg_tcpip_driver_rp2040_rmii_init,
     mg_tcpip_driver_rp2040_rmii_tx,
-    mg_tcpip_driver_rp2040_rmii_rx,
+    NULL,
     mg_tcpip_driver_rp2040_rmii_up,
 };
diff --git a/examples/rp2040/pico-rmii/main.c b/examples/rp2040/pico-rmii/main.c
index d7e69cbc..6ea96ea1 100644
--- a/examples/rp2040/pico-rmii/main.c
+++ b/examples/rp2040/pico-rmii/main.c
@@ -42,6 +42,8 @@ int main(void) {
   struct mg_tcpip_if mif = {
       .mac = {2, 0, 1, 2, 3, 5},
       .ip = 0,
+      .enable_mac_check = true,
+      .enable_crc32_check = true,
       .driver = &mg_tcpip_driver_rp2040_rmii,
       .driver_data = &driver_data,
   };
diff --git a/mongoose.c b/mongoose.c
index 7a0971c9..6b258f5b 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -5672,11 +5672,16 @@ uint16_t mg_ntohs(uint16_t net) {
 }
 
 uint32_t mg_crc32(uint32_t crc, const char *buf, size_t len) {
-  int i;
+  static const uint32_t crclut[16] = {
+      // table for polynomial 0xEDB88320 (reflected)
+      0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190, 0x6B6B51F4,
+      0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C,
+      0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C};
   crc = ~crc;
   while (len--) {
-    crc ^= *(unsigned char *) buf++;
-    for (i = 0; i < 8; i++) crc = crc & 1 ? (crc >> 1) ^ 0xedb88320 : crc >> 1;
+    uint8_t byte = *(uint8_t *)buf++;
+    crc = crclut[(crc ^ byte) & 0x0F] ^ (crc >> 4);
+    crc = crclut[(crc ^ (byte >> 4)) & 0x0F] ^ (crc >> 4);
   }
   return ~crc;
 }
@@ -5755,7 +5760,6 @@ uint64_t mg_millis(void) {
 }
 #endif
 
-
 #ifdef MG_ENABLE_LINES
 #line 1 "src/ws.c"
 #endif
@@ -7867,10 +7871,16 @@ static void mg_tcpip_rx(struct mg_tcpip_if *ifp, void *buf, size_t len) {
   pkt.raw.len = len;
   pkt.eth = (struct eth *) buf;
   if (pkt.raw.len < sizeof(*pkt.eth)) return;  // Truncated - runt?
-  if (memcmp(pkt.eth->dst, ifp->mac, sizeof(pkt.eth->dst)) != 0 &&
-      memcmp(pkt.eth->dst, broadcast, sizeof(pkt.eth->dst)) != 0) {
-    // Not for us. Drop silently
-  } else if (pkt.eth->type == mg_htons(0x806)) {
+  if (ifp->enable_mac_check &&
+      memcmp(pkt.eth->dst, ifp->mac, sizeof(pkt.eth->dst)) != 0 &&
+      memcmp(pkt.eth->dst, broadcast, sizeof(pkt.eth->dst)) != 0)
+    return;
+  if (ifp->enable_crc32_check && len > 4) {
+    len -= 4;  // TODO(scaprile): check on bigendian
+    uint32_t crc = mg_crc32(0, (const char *) buf, len);
+    if (memcmp((void *) ((size_t) buf + len), &crc, sizeof(crc))) return;
+  }
+  if (pkt.eth->type == mg_htons(0x806)) {
     pkt.arp = (struct arp *) (pkt.eth + 1);
     if (sizeof(*pkt.eth) + sizeof(*pkt.arp) > pkt.raw.len) return;  // Truncated
     rx_arp(ifp, &pkt);
@@ -7971,11 +7981,6 @@ void mg_tcpip_qwrite(void *buf, size_t len, struct mg_tcpip_if *ifp) {
   }
 }
 
-size_t mg_tcpip_driver_rx(void *buf, size_t len, struct mg_tcpip_if *ifp) {
-  (void) buf, (void) len, (void) ifp;
-  return 0;
-}
-
 void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
   // If MAC address is not set, make a random one
   if (ifp->mac[0] == 0 && ifp->mac[1] == 0 && ifp->mac[2] == 0 &&
@@ -7990,7 +7995,8 @@ void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
   } else {
     size_t framesize = 1540;
     ifp->tx.ptr = (char *) calloc(1, framesize), ifp->tx.len = framesize;
-    ifp->recv_queue.size = ifp->driver->rx ? framesize : 8192;
+    if (ifp->recv_queue.size == 0)
+      ifp->recv_queue.size = ifp->driver->rx ? framesize : 8192;
     ifp->recv_queue.buf = (char *) calloc(1, ifp->recv_queue.size);
     ifp->timer_1000ms = mg_millis();
     mgr->priv = ifp;
diff --git a/mongoose.h b/mongoose.h
index 6bc4bce9..69496b80 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -1514,11 +1514,13 @@ struct mg_tcpip_driver {
 
 // Network interface
 struct mg_tcpip_if {
-  uint8_t mac[6];                  // MAC address. Must be set to a valid MAC
-  uint32_t ip, mask, gw;           // IP address, mask, default gateway
-  struct mg_str tx;                // Output (TX) buffer
-  bool enable_dhcp_client;         // Enable DCHP client
-  bool enable_dhcp_server;         // Enable DCHP server
+  uint8_t mac[6];           // MAC address. Must be set to a valid MAC
+  uint32_t ip, mask, gw;    // IP address, mask, default gateway
+  struct mg_str tx;         // Output (TX) buffer
+  bool enable_dhcp_client;  // Enable DCHP client
+  bool enable_dhcp_server;  // Enable DCHP server
+  bool enable_crc32_check;  // Do a CRC check on rx frames and strip it
+  bool enable_mac_check;    // Do a MAC check on rx frames
   struct mg_tcpip_driver *driver;  // Low level driver
   void *driver_data;               // Driver-specific data
   struct mg_mgr *mgr;              // Mongoose event manager
@@ -1543,9 +1545,6 @@ struct mg_tcpip_if {
 void mg_tcpip_init(struct mg_mgr *, struct mg_tcpip_if *);
 void mg_tcpip_free(struct mg_tcpip_if *);
 void mg_tcpip_qwrite(void *buf, size_t len, struct mg_tcpip_if *ifp);
-size_t mg_tcpip_qread(void *buf, struct mg_tcpip_if *ifp);
-// conveniency rx function for IRQ-driven drivers
-size_t mg_tcpip_driver_rx(void *buf, size_t len, struct mg_tcpip_if *ifp);
 
 extern struct mg_tcpip_driver mg_tcpip_driver_stm32;
 extern struct mg_tcpip_driver mg_tcpip_driver_w5500;
diff --git a/src/tcpip/tcpip.c b/src/tcpip/tcpip.c
index 5273f608..02330b2c 100644
--- a/src/tcpip/tcpip.c
+++ b/src/tcpip/tcpip.c
@@ -693,10 +693,16 @@ static void mg_tcpip_rx(struct mg_tcpip_if *ifp, void *buf, size_t len) {
   pkt.raw.len = len;
   pkt.eth = (struct eth *) buf;
   if (pkt.raw.len < sizeof(*pkt.eth)) return;  // Truncated - runt?
-  if (memcmp(pkt.eth->dst, ifp->mac, sizeof(pkt.eth->dst)) != 0 &&
-      memcmp(pkt.eth->dst, broadcast, sizeof(pkt.eth->dst)) != 0) {
-    // Not for us. Drop silently
-  } else if (pkt.eth->type == mg_htons(0x806)) {
+  if (ifp->enable_mac_check &&
+      memcmp(pkt.eth->dst, ifp->mac, sizeof(pkt.eth->dst)) != 0 &&
+      memcmp(pkt.eth->dst, broadcast, sizeof(pkt.eth->dst)) != 0)
+    return;
+  if (ifp->enable_crc32_check && len > 4) {
+    len -= 4;  // TODO(scaprile): check on bigendian
+    uint32_t crc = mg_crc32(0, (const char *) buf, len);
+    if (memcmp((void *) ((size_t) buf + len), &crc, sizeof(crc))) return;
+  }
+  if (pkt.eth->type == mg_htons(0x806)) {
     pkt.arp = (struct arp *) (pkt.eth + 1);
     if (sizeof(*pkt.eth) + sizeof(*pkt.arp) > pkt.raw.len) return;  // Truncated
     rx_arp(ifp, &pkt);
@@ -797,11 +803,6 @@ void mg_tcpip_qwrite(void *buf, size_t len, struct mg_tcpip_if *ifp) {
   }
 }
 
-size_t mg_tcpip_driver_rx(void *buf, size_t len, struct mg_tcpip_if *ifp) {
-  (void) buf, (void) len, (void) ifp;
-  return 0;
-}
-
 void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
   // If MAC address is not set, make a random one
   if (ifp->mac[0] == 0 && ifp->mac[1] == 0 && ifp->mac[2] == 0 &&
@@ -816,7 +817,8 @@ void mg_tcpip_init(struct mg_mgr *mgr, struct mg_tcpip_if *ifp) {
   } else {
     size_t framesize = 1540;
     ifp->tx.ptr = (char *) calloc(1, framesize), ifp->tx.len = framesize;
-    ifp->recv_queue.size = ifp->driver->rx ? framesize : 8192;
+    if (ifp->recv_queue.size == 0)
+      ifp->recv_queue.size = ifp->driver->rx ? framesize : 8192;
     ifp->recv_queue.buf = (char *) calloc(1, ifp->recv_queue.size);
     ifp->timer_1000ms = mg_millis();
     mgr->priv = ifp;
diff --git a/src/tcpip/tcpip.h b/src/tcpip/tcpip.h
index 371faed4..677dba60 100644
--- a/src/tcpip/tcpip.h
+++ b/src/tcpip/tcpip.h
@@ -15,11 +15,13 @@ struct mg_tcpip_driver {
 
 // Network interface
 struct mg_tcpip_if {
-  uint8_t mac[6];                  // MAC address. Must be set to a valid MAC
-  uint32_t ip, mask, gw;           // IP address, mask, default gateway
-  struct mg_str tx;                // Output (TX) buffer
-  bool enable_dhcp_client;         // Enable DCHP client
-  bool enable_dhcp_server;         // Enable DCHP server
+  uint8_t mac[6];           // MAC address. Must be set to a valid MAC
+  uint32_t ip, mask, gw;    // IP address, mask, default gateway
+  struct mg_str tx;         // Output (TX) buffer
+  bool enable_dhcp_client;  // Enable DCHP client
+  bool enable_dhcp_server;  // Enable DCHP server
+  bool enable_crc32_check;  // Do a CRC check on rx frames and strip it
+  bool enable_mac_check;    // Do a MAC check on rx frames
   struct mg_tcpip_driver *driver;  // Low level driver
   void *driver_data;               // Driver-specific data
   struct mg_mgr *mgr;              // Mongoose event manager
@@ -44,9 +46,6 @@ struct mg_tcpip_if {
 void mg_tcpip_init(struct mg_mgr *, struct mg_tcpip_if *);
 void mg_tcpip_free(struct mg_tcpip_if *);
 void mg_tcpip_qwrite(void *buf, size_t len, struct mg_tcpip_if *ifp);
-size_t mg_tcpip_qread(void *buf, struct mg_tcpip_if *ifp);
-// conveniency rx function for IRQ-driven drivers
-size_t mg_tcpip_driver_rx(void *buf, size_t len, struct mg_tcpip_if *ifp);
 
 extern struct mg_tcpip_driver mg_tcpip_driver_stm32;
 extern struct mg_tcpip_driver mg_tcpip_driver_w5500;
@@ -64,8 +63,8 @@ struct mg_tcpip_spi {
 
 #if MG_ENABLE_TCPIP
 #if !defined(MG_ENABLE_DRIVER_STM32H) && !defined(MG_ENABLE_DRIVER_TM4C)
-  #define MG_ENABLE_DRIVER_STM32 1
+#define MG_ENABLE_DRIVER_STM32 1
 #else
-  #define MG_ENABLE_DRIVER_STM32 0
+#define MG_ENABLE_DRIVER_STM32 0
 #endif
 #endif
diff --git a/src/util.c b/src/util.c
index 6f7f5c0c..e2d44730 100644
--- a/src/util.c
+++ b/src/util.c
@@ -48,11 +48,16 @@ uint16_t mg_ntohs(uint16_t net) {
 }
 
 uint32_t mg_crc32(uint32_t crc, const char *buf, size_t len) {
-  int i;
+  static const uint32_t crclut[16] = {
+      // table for polynomial 0xEDB88320 (reflected)
+      0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC, 0x76DC4190, 0x6B6B51F4,
+      0x4DB26158, 0x5005713C, 0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C,
+      0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C};
   crc = ~crc;
   while (len--) {
-    crc ^= *(unsigned char *) buf++;
-    for (i = 0; i < 8; i++) crc = crc & 1 ? (crc >> 1) ^ 0xedb88320 : crc >> 1;
+    uint8_t byte = *(uint8_t *)buf++;
+    crc = crclut[(crc ^ byte) & 0x0F] ^ (crc >> 4);
+    crc = crclut[(crc ^ (byte >> 4)) & 0x0F] ^ (crc >> 4);
   }
   return ~crc;
 }
@@ -130,4 +135,3 @@ uint64_t mg_millis(void) {
 #endif
 }
 #endif
-

From 38b129de667b29ff4e344ce3221f0ae6f7326d8c Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@cesanta.com>
Date: Tue, 28 Feb 2023 14:04:02 -0300
Subject: [PATCH 5/7] Test some examples on Windows

closes #2047
---
 .github/workflows/test.yml | 28 +++++++++++++++++++++-------
 Makefile                   |  6 ++++++
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 756f00e3..e50ac83e 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -52,13 +52,6 @@ jobs:
       run: sudo apt -y update ; sudo apt -y install libmbedtls-dev valgrind
     - if: ${{ env.GO == 1 }}
       run: make unamalgamated && make valgrind && make mg_prefix
-  examples:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v3
-    - run: sudo apt -y install libmbedtls-dev libpcap-dev
-    - run: make clean examples
-    - run: make clean test MG_ENABLE_POLL=1
   macos:
     runs-on: macos-latest
     env: { HOMEBREW_NO_AUTO_UPDATE: 1 }
@@ -101,6 +94,27 @@ jobs:
     - uses: actions/checkout@v3
     - run: make riscv
 
+  examples:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - run: sudo apt -y install libmbedtls-dev libpcap-dev
+    - run: make clean examples
+    - run: make clean test MG_ENABLE_POLL=1
+  examples_win:
+    runs-on: windows-latest
+    steps:
+    - uses: actions/checkout@v3
+#    - uses: egor-tensin/setup-mingw@v2
+#      with:
+#        platform: x64
+    - name: test they build
+      run: make examples_win
+      shell: cmd
+    - name: test they clean
+      run: make clean_examples_win
+      shell: cmd
+
   test_f7:
     runs-on: ubuntu-latest
     steps:
diff --git a/Makefile b/Makefile
index dd954698..1497021f 100644
--- a/Makefile
+++ b/Makefile
@@ -13,6 +13,7 @@ IPV6 ?= 1
 ASAN ?= -fsanitize=address,undefined,alignment -fno-sanitize-recover=all -fno-omit-frame-pointer -fno-common
 ASAN_OPTIONS ?= detect_leaks=1
 EXAMPLES := $(dir $(wildcard examples/*/Makefile))
+EXAMPLES_WIN := $(dir $(wildcard examples/device-dashboard/Makefile) $(wildcard examples/file-*/Makefile) $(wildcard examples/http-*/Makefile) $(wildcard examples/mqtt-*/Makefile) $(wildcard examples/websocket-*/Makefile) $(wildcard examples/webui-*/Makefile))
 PREFIX ?= /usr/local
 VERSION ?= $(shell cut -d'"' -f2 src/version.h)
 COMMON_CFLAGS ?= $(C_WARN) $(WARN) $(INCS) $(DEFS) -DMG_ENABLE_IPV6=$(IPV6) $(TFLAGS) -pthread
@@ -57,6 +58,11 @@ mip_tap_test: test/mip_tap_test.c mongoose.c mongoose.h Makefile
 examples:
 	@for X in $(EXAMPLES); do test -f $$X/Makefile || continue; $(MAKE) -C $$X example || exit 1; done
 
+examples_win:
+	$(foreach X, $(EXAMPLES_WIN), $(MAKE) -C $(X) example &)
+clean_examples_win:
+	$(foreach X, $(EXAMPLES_WIN), $(MAKE) -C $(X) clean &)
+
 test/packed_fs.c: Makefile src/ssi.h test/fuzz.c test/data/a.txt
 	$(CC) $(CFLAGS) test/pack.c -o pack
 	$(RUN) ./pack Makefile src/ssi.h test/fuzz.c test/data/a.txt test/data/range.txt > $@

From 9ba20304c2dd394c0aa45f84a799d575b5ee18cf Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@users.noreply.github.com>
Date: Tue, 28 Feb 2023 14:14:57 -0300
Subject: [PATCH 6/7] Update test.yml

---
 .github/workflows/test.yml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index e50ac83e..514f9a82 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -114,6 +114,13 @@ jobs:
     - name: test they clean
       run: make clean_examples_win
       shell: cmd
+  examples_mac:
+    runs-on: macos-latest
+    env: { HOMEBREW_NO_AUTO_UPDATE: 1 }
+    steps:
+    - uses: actions/checkout@v3
+    - run: make examples_mac
+    - run: make clean_examples_mac
 
   test_f7:
     runs-on: ubuntu-latest

From 873e4d6547efa6b17a1f6f68371711f0a35c2901 Mon Sep 17 00:00:00 2001
From: "Sergio R. Caprile" <scaprile@cesanta.com>
Date: Tue, 28 Feb 2023 14:18:39 -0300
Subject: [PATCH 7/7] Update Makefile

---
 Makefile | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 1497021f..957f5e1a 100644
--- a/Makefile
+++ b/Makefile
@@ -13,14 +13,16 @@ IPV6 ?= 1
 ASAN ?= -fsanitize=address,undefined,alignment -fno-sanitize-recover=all -fno-omit-frame-pointer -fno-common
 ASAN_OPTIONS ?= detect_leaks=1
 EXAMPLES := $(dir $(wildcard examples/*/Makefile))
+EXAMPLES_MAC := $(filter-out examples/mip-pcap/ examples/mip-tap/, $(EXAMPLES))
 EXAMPLES_WIN := $(dir $(wildcard examples/device-dashboard/Makefile) $(wildcard examples/file-*/Makefile) $(wildcard examples/http-*/Makefile) $(wildcard examples/mqtt-*/Makefile) $(wildcard examples/websocket-*/Makefile) $(wildcard examples/webui-*/Makefile))
+EXAMPLES_EMBEDDED := $(filter-out $(wildcard examples/zephyr/*/), $(dir $(wildcard examples/*/*/Makefile)))
 PREFIX ?= /usr/local
 VERSION ?= $(shell cut -d'"' -f2 src/version.h)
 COMMON_CFLAGS ?= $(C_WARN) $(WARN) $(INCS) $(DEFS) -DMG_ENABLE_IPV6=$(IPV6) $(TFLAGS) -pthread
 CFLAGS ?= $(OPTS) $(ASAN) $(COMMON_CFLAGS)
 VALGRIND_CFLAGS ?= $(OPTS) $(COMMON_CFLAGS)
 VALGRIND_RUN ?= valgrind --tool=memcheck --gen-suppressions=all --leak-check=full --show-leak-kinds=all --leak-resolution=high --track-origins=yes --error-exitcode=1 --exit-on-first-error=yes --fair-sched=yes
-.PHONY: examples test valgrind mip_test
+.PHONY: clean_examples examples mip_test test valgrind
 
 ifeq "$(findstring ++,$(CC))" ""
 # $(CC) does not end with ++, i.e. we're using C. Apply C flags
@@ -57,6 +59,13 @@ mip_tap_test: test/mip_tap_test.c mongoose.c mongoose.h Makefile
 
 examples:
 	@for X in $(EXAMPLES); do test -f $$X/Makefile || continue; $(MAKE) -C $$X example || exit 1; done
+clean_examples:
+	for X in $(EXAMPLES); do test -f $$X/Makefile || continue; $(MAKE) -C $$X clean || exit 1; done
+
+examples_mac:
+	for X in $(EXAMPLES_MAC); do test -f $$X/Makefile || continue; $(MAKE) -C $$X example || exit 1; done
+clean_examples_mac:
+	for X in $(EXAMPLES_MAC); do test -f $$X/Makefile || continue; $(MAKE) -C $$X clean || exit 1; done
 
 examples_win:
 	$(foreach X, $(EXAMPLES_WIN), $(MAKE) -C $(X) example &)
@@ -187,6 +196,11 @@ mongoose.c: Makefile $(wildcard src/*.c) $(wildcard src/tcpip/*.c)
 mongoose.h: $(HDRS) Makefile
 	(cat src/license.h; echo; echo '#ifndef MONGOOSE_H'; echo '#define MONGOOSE_H'; echo; cat src/version.h ; echo; echo '#ifdef __cplusplus'; echo 'extern "C" {'; echo '#endif'; cat src/arch.h src/arch_*.h src/net_*.h src/config.h src/str.h src/queue.h src/fmt.h src/log.h src/timer.h src/fs.h src/util.h src/url.h src/iobuf.h src/base64.h src/md5.h src/sha1.h src/event.h src/net.h src/http.h src/ssi.h src/tls.h src/tls_mbed.h src/tls_openssl.h src/ws.h src/sntp.h src/mqtt.h src/dns.h src/json.h src/rpc.h src/tcpip/tcpip.h src/tcpip/driver_*.h | sed -e '/keep/! s,#include ".*,,' -e 's,^#pragma once,,'; echo; echo '#ifdef __cplusplus'; echo '}'; echo '#endif'; echo '#endif  // MONGOOSE_H')> $@
 
-clean:
+
+clean: clean_examples clean_embedded
 	rm -rf $(PROG) *.exe *.o *.dSYM *_test* ut fuzzer *.gcov *.gcno *.gcda *.obj *.exe *.ilk *.pdb slow-unit* _CL_* infer-out data.txt crash-* test/packed_fs.c pack arduino tmp
-	find examples -maxdepth 3 -name zephyr -prune -o -name Makefile -print | xargs dirname | xargs -n1 make clean -C
+	#find examples -maxdepth 3 -name zephyr -prune -o -name Makefile -print | xargs dirname | xargs -n1 make clean -C
+
+clean_embedded:
+	for X in $(EXAMPLES_EMBEDDED); do test -f $$X/Makefile || continue; $(MAKE) -C $$X clean || exit 1; done
+