ESP: lwIP fixes (#908)

Before this PR, lwIP caused null pointer dereferences in my setup (see
https://savannah.nongnu.org/bugs/?59831).
It was also possible to use APIs that expected the core mutex to be
locked without locking it.
Now it will instead panic, letting you know.
My project is now much more stable, and I haven't encountered any
crashes.

Author: andreacoradi

examples/espressif/esp/src/lwip/exports.zig

@@ -24,6 +24,13 @@ export fn lwip_unlock_core_mutex() void {
     core_mutex.unlock();
 }
 
+export fn lwip_assert_core_locked() void {
+    if (c.lock_tcpip_core == null) return;
+
+    const mutex: *rtos.Mutex = @ptrCast(@alignCast(c.lock_tcpip_core));
+    std.debug.assert(mutex.locked != null);
+}
+
 export fn lwip_rand() u32 {
     return esp.rng.random_u32();
 }

examples/espressif/esp/src/lwip/include/arch/cc.h

@@ -9,9 +9,12 @@ typedef unsigned int sys_prot_t;
 extern uint32_t lwip_rand(void);
 extern void lwip_lock_core_mutex();
 extern void lwip_unlock_core_mutex();
+extern void lwip_assert_core_locked();
 extern void lwip_assert(const char *msg, const char *file, int line);
 extern void lwip_diag(const char *msg, const char *file, int line);
 
+#define LWIP_ASSERT_CORE_LOCKED()   do { lwip_assert_core_locked(); } while (0)
+
 #define LWIP_PLATFORM_DIAG(x)                                                  \
     do {                                                                       \
         lwip_diag((msg), __FILE__, __LINE__);                                  \

modules/lwip/build.zig

@@ -72,6 +72,7 @@ const files = [_][]const u8{
     "core/ipv4/ip4_addr.c",
     "core/ipv4/igmp.c",
     "core/ipv4/icmp.c",
+    "core/ipv4/acd.c",
 
     // IPv6 implementation:
     "core/ipv6/icmp6.c",

modules/lwip/build.zig.zon

@@ -7,9 +7,9 @@
     },
     .dependencies = .{
         .lwip = .{
-            //.url = "https://download.savannah.nongnu.org/releases/lwip/lwip-2.1.3.zip",
-            .url = "https://github.com/Ashet-Technologies/deps/raw/refs/heads/main/lwip-2.1.3.zip",
-            .hash = "N-V-__8AAKCP6ADEah-rtpC4uEsB_-GFFCqsNInUAJY7bH3S",
+            // .url = "https://download.savannah.nongnu.org/releases/lwip/lwip-2.2.1.zip",
+            .url = "https://github.com/lwip-tcpip/lwip/archive/refs/tags/STABLE-2_2_1_RELEASE.zip",
+            .hash = "N-V-__8AAGSTdQCcOKeNITCRoYez502saFXZqz4ucBJ4xTa9",
         },
     },
 }