From 4989cfd8cbf814ecb0800289e3f14020dc6cf24f Mon Sep 17 00:00:00 2001
From: Ian Gulliver <github@flamingcow.io>
Date: Sun, 5 Apr 2026 21:30:21 +0900
Subject: [PATCH] Use pico_rand for DHCP xid, run cmake in load command

---
 CMakeLists.txt   | 2 +-
 cmd/load/main.go | 8 ++++++++
 dhcp.cpp         | 3 ++-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 993cd4a..a6f9adc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -31,4 +31,4 @@ pico_enable_stdio_uart(picomap 0)
 
 pico_add_extra_outputs(picomap)
 
-target_link_libraries(picomap pico_stdlib tinyusb_device tinyusb_board hardware_pio hardware_spi hardware_dma hardware_clocks)
+target_link_libraries(picomap pico_stdlib pico_rand tinyusb_device tinyusb_board hardware_pio hardware_spi hardware_dma hardware_clocks)
diff --git a/cmd/load/main.go b/cmd/load/main.go
index 541deaf..9a095e5 100644
--- a/cmd/load/main.go
+++ b/cmd/load/main.go
@@ -26,6 +26,14 @@ func main() {
 }
 
 func run(buildDir string) error {
+	fmt.Println("Configuring...")
+	cmake := exec.Command("cmake", "-B", buildDir)
+	cmake.Stdout = os.Stdout
+	cmake.Stderr = os.Stderr
+	if err := cmake.Run(); err != nil {
+		return fmt.Errorf("cmake failed: %w", err)
+	}
+
 	fmt.Println("Building...")
 	cmd := exec.Command("make", "-C", buildDir)
 	cmd.Stdout = os.Stdout
diff --git a/dhcp.cpp b/dhcp.cpp
index 45e9c94..d323ec7 100644
--- a/dhcp.cpp
+++ b/dhcp.cpp
@@ -1,5 +1,6 @@
 #include "dhcp.h"
 #include <span>
+#include "pico/rand.h"
 #include "w6300.h"
 
 namespace dhcp_opt {
@@ -15,7 +16,7 @@ struct __attribute__((packed)) dhcp_discover {
     uint8_t htype = 1;
     uint8_t hlen = 6;
     uint8_t hops = 0;
-    uint32_t xid = __builtin_bswap32(0x12345678);
+    uint32_t xid = __builtin_bswap32(static_cast<uint32_t>(get_rand_64()));
     uint16_t secs = 0;
     uint16_t flags = __builtin_bswap16(0x8000);
     std::array<uint8_t, 4> ciaddr = {};