Add basic use-after-free checking in limited places.
[ldk-java] / java_strings.py
index 90226fa4dd37eef15e2dbc57da0ea304a1c39824..1d28d0d1007e0a12acbc9cf9e792a9603ef910dc 100644 (file)
@@ -1,5 +1,6 @@
 from bindingstypes import *
 from enum import Enum
+import sys
 
 class Target(Enum):
     JAVA = 1,
@@ -23,6 +24,13 @@ class Consts:
 
         self.bindings_header = """package org.ldk.impl;
 import org.ldk.enums.*;
+import org.ldk.impl.version;
+import java.io.File;
+import java.io.InputStream;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
 
 public class bindings {
        public static class VecOrSliceDef {
@@ -34,10 +42,30 @@ public class bindings {
                }
        }
        static {
-               System.loadLibrary(\"lightningjni\");
+               try {
+                       // Try to load natively first, this works on Android and in testing.
+                       System.loadLibrary(\"lightningjni\");
+               } catch (UnsatisfiedLinkError system_load_err) {
+                       // Otherwise try to load from the library jar.
+                       File tmpdir = new File(System.getProperty("java.io.tmpdir"), "ldk-java-nativelib");
+                       tmpdir.mkdir(); // If it fails to create, assume it was there already
+                       tmpdir.deleteOnExit();
+                       String libname = "liblightningjni_" + System.getProperty("os.name").replaceAll(" ", "") +
+                               "-" + System.getProperty("os.arch").replaceAll(" ", "") + ".nativelib";
+                       try (InputStream is = bindings.class.getResourceAsStream("/" + libname)) {
+                               Path libpath = new File(tmpdir.toPath().toString(), "liblightningjni.so").toPath();
+                               Files.copy(is, libpath, StandardCopyOption.REPLACE_EXISTING);
+                               Runtime.getRuntime().load(libpath.toString());
+                       } catch (Exception e) {
+                               System.err.println("Failed to load LDK native library.");
+                               System.err.println("System LDK native library load failed with: " + system_load_err);
+                               System.err.println("Resource-based LDK native library load failed with: " + e);
+                               throw new IllegalArgumentException(e);
+                       }
+               }
                init(java.lang.Enum.class, VecOrSliceDef.class);
                init_class_cache();
-               if (!get_lib_version_string().equals(get_ldk_java_bindings_version()))
+               if (!get_lib_version_string().equals(version.get_ldk_java_bindings_version()))
                        throw new IllegalArgumentException("Compiled LDK library and LDK class failes do not match");
                // Fetching the LDK versions from C also checks that the header and binaries match
                get_ldk_c_bindings_version();
@@ -47,9 +75,6 @@ public class bindings {
        static native void init_class_cache();
        static native String get_lib_version_string();
 
-       public static String get_ldk_java_bindings_version() {
-               return "<git_version_ldk_garbagecollected>";
-       }
        public static native String get_ldk_c_bindings_version();
        public static native String get_ldk_version();
 
@@ -66,12 +91,20 @@ public class bindings {
        public static native long new_empty_slice_vec();
 
 """
+        self.bindings_version_file = """package org.ldk.impl;
+
+public class version {
+       public static String get_ldk_java_bindings_version() {
+               return "<git_version_ldk_garbagecollected>";
+       }
+}"""
 
         self.bindings_footer = "}\n"
 
         self.util_fn_pfx = """package org.ldk.structs;
 import org.ldk.impl.bindings;
 import java.util.Arrays;
+import javax.annotation.Nullable;
 import org.ldk.enums.*;
 
 public class UtilMethods {
@@ -82,12 +115,14 @@ import java.util.LinkedList;
 class CommonBase {
        long ptr;
        LinkedList<Object> ptrs_to = new LinkedList();
-       protected CommonBase(long ptr) { this.ptr = ptr; }
-       public long _test_only_get_ptr() { return this.ptr; }
+       protected CommonBase(long ptr) { assert ptr < 0 || ptr > 1024; this.ptr = ptr; }
 }
 """
 
-        self.c_file_pfx = """#include \"org_ldk_impl_bindings.h\"
+        self.c_file_pfx = """#include <jni.h>
+// On OSX jlong (ie long long) is not equivalent to int64_t, so we override here
+#define int64_t jlong
+#include \"org_ldk_impl_bindings.h\"
 #include <lightning.h>
 #include <string.h>
 #include <stdatomic.h>
@@ -124,13 +159,16 @@ void __attribute__((constructor)) spawn_stderr_redirection() {
         else:
             self.c_file_pfx = self.c_file_pfx + "#define DEBUG_PRINT(...) fprintf(stderr, __VA_ARGS__)\n"
 
-        if not DEBUG:
+        if not DEBUG or sys.platform == "darwin":
             self.c_file_pfx = self.c_file_pfx + """#define MALLOC(a, _) malloc(a)
 #define FREE(p) if ((uint64_t)(p) > 1024) { free(p); }
-#define DO_ASSERT(a) (void)(a)
+#define CHECK_ACCESS(p)
+"""
+        if not DEBUG:
+            self.c_file_pfx += """#define DO_ASSERT(a) (void)(a)
 #define CHECK(a)
 """
-        else:
+        if DEBUG:
             self.c_file_pfx = self.c_file_pfx + """#include <assert.h>
 // Always run a, then assert it is true:
 #define DO_ASSERT(a) do { bool _assert_val = (a); assert(_assert_val); } while(0)
@@ -144,7 +182,10 @@ void __attribute__((constructor)) debug_log_version() {
                DEBUG_PRINT("LDK C Bindings version did not match the header we built against\\n");
        DEBUG_PRINT("Loaded LDK-Java Bindings with LDK %s and LDK-C-Bindings %s\\n", check_get_ldk_version(), check_get_ldk_bindings_version());
 }
+"""
 
+            if sys.platform != "darwin":
+                self.c_file_pfx += """
 // Running a leak check across all the allocations and frees of the JDK is a mess,
 // so instead we implement our own naive leak checker here, relying on the -wrap
 // linker option to wrap malloc/calloc/realloc/free, tracking everyhing allocated
@@ -152,8 +193,8 @@ void __attribute__((constructor)) debug_log_version() {
 #include <threads.h>
 """
 
-            if self.target == Target.ANDROID:
-                self.c_file_pfx = self.c_file_pfx + """
+                if self.target == Target.ANDROID:
+                    self.c_file_pfx = self.c_file_pfx + """
 #include <unwind.h>
 #include <dlfcn.h>
 
@@ -194,14 +235,15 @@ void backtrace_symbols_fd(void ** buffer, int count, int _fd) {
        }
 }
 """
-            else:
-                self.c_file_pfx = self.c_file_pfx + "#include <execinfo.h>\n"
-            self.c_file_pfx = self.c_file_pfx + """
+                else:
+                    self.c_file_pfx = self.c_file_pfx + "#include <execinfo.h>\n"
+                self.c_file_pfx = self.c_file_pfx + """
 #include <unistd.h>
-static mtx_t allocation_mtx;
+#include <pthread.h>
+static pthread_mutex_t allocation_mtx;
 
 void __attribute__((constructor)) init_mtx() {
-       DO_ASSERT(mtx_init(&allocation_mtx, mtx_plain) == thrd_success);
+       DO_ASSERT(!pthread_mutex_init(&allocation_mtx, NULL));
 }
 
 #define BT_MAX 128
@@ -223,10 +265,10 @@ static void new_allocation(void* res, const char* struct_name, size_t len) {
        new_alloc->struct_name = struct_name;
        new_alloc->bt_len = backtrace(new_alloc->bt, BT_MAX);
        new_alloc->alloc_len = len;
-       DO_ASSERT(mtx_lock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(!pthread_mutex_lock(&allocation_mtx));
        new_alloc->next = allocation_ll;
        allocation_ll = new_alloc;
-       DO_ASSERT(mtx_unlock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(!pthread_mutex_unlock(&allocation_mtx));
 }
 static void* MALLOC(size_t len, const char* struct_name) {
        void* res = __real_malloc(len);
@@ -236,22 +278,22 @@ static void* MALLOC(size_t len, const char* struct_name) {
 void __real_free(void* ptr);
 static void alloc_freed(void* ptr) {
        allocation* p = NULL;
-       DO_ASSERT(mtx_lock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(!pthread_mutex_lock(&allocation_mtx));
        allocation* it = allocation_ll;
        while (it->ptr != ptr) {
                p = it; it = it->next;
                if (it == NULL) {
-                       DEBUG_PRINT("Tried to free unknown pointer %p at:\\n", ptr);
+                       DEBUG_PRINT("ERROR: Tried to free unknown pointer %p at:\\n", ptr);
                        void* bt[BT_MAX];
                        int bt_len = backtrace(bt, BT_MAX);
                        backtrace_symbols_fd(bt, bt_len, STDERR_FILENO);
                        DEBUG_PRINT("\\n\\n");
-                       DO_ASSERT(mtx_unlock(&allocation_mtx) == thrd_success);
+                       DO_ASSERT(!pthread_mutex_unlock(&allocation_mtx));
                        return; // addrsan should catch malloc-unknown and print more info than we have
                }
        }
        if (p) { p->next = it->next; } else { allocation_ll = it->next; }
-       DO_ASSERT(mtx_unlock(&allocation_mtx) == thrd_success);
+       DO_ASSERT(!pthread_mutex_unlock(&allocation_mtx));
        DO_ASSERT(it->ptr == ptr);
        __real_free(it);
 }
@@ -277,6 +319,24 @@ void __wrap_free(void* ptr) {
        __real_free(ptr);
 }
 
+static void CHECK_ACCESS(void* ptr) {
+       DO_ASSERT(!pthread_mutex_lock(&allocation_mtx));
+       allocation* it = allocation_ll;
+       while (it->ptr != ptr) {
+               it = it->next;
+               if (it == NULL) {
+                       DEBUG_PRINT("ERROR: Tried to access unknown pointer %p at:\\n", ptr);
+                       void* bt[BT_MAX];
+                       int bt_len = backtrace(bt, BT_MAX);
+                       backtrace_symbols_fd(bt, bt_len, STDERR_FILENO);
+                       DEBUG_PRINT("\\n\\n");
+                       DO_ASSERT(!pthread_mutex_unlock(&allocation_mtx));
+                       return; // addrsan should catch and print more info than we have
+               }
+       }
+       DO_ASSERT(!pthread_mutex_unlock(&allocation_mtx));
+}
+
 void* __real_realloc(void* ptr, size_t newlen);
 void* __wrap_realloc(void* ptr, size_t len) {
        if (ptr != NULL) alloc_freed(ptr);
@@ -425,16 +485,17 @@ static inline LDKStr java_to_owned_str(JNIEnv *env, jstring str) {
        return res;
 }
 
-JNIEXPORT jstring JNICALL Java_org_ldk_impl_bindings_get_1lib_1version_1string(JNIEnv *env, jclass _c) {
-       return str_ref_to_java(env, "<git_version_ldk_garbagecollected>", strlen("<git_version_ldk_garbagecollected>"));
-}
 JNIEXPORT jstring JNICALL Java_org_ldk_impl_bindings_get_1ldk_1c_1bindings_1version(JNIEnv *env, jclass _c) {
        return str_ref_to_java(env, check_get_ldk_bindings_version(), strlen(check_get_ldk_bindings_version()));
 }
 JNIEXPORT jstring JNICALL Java_org_ldk_impl_bindings_get_1ldk_1version(JNIEnv *env, jclass _c) {
        return str_ref_to_java(env, check_get_ldk_version(), strlen(check_get_ldk_version()));
 }
+#include "version.c"
 """
+        self.c_version_file = """JNIEXPORT jstring JNICALL Java_org_ldk_impl_bindings_get_1lib_1version_1string(JNIEnv *env, jclass _c) {
+       return str_ref_to_java(env, "<git_version_ldk_garbagecollected>", strlen("<git_version_ldk_garbagecollected>"));
+}"""
 
         self.hu_struct_file_prefix = """package org.ldk.structs;
 
@@ -442,6 +503,7 @@ import org.ldk.impl.bindings;
 import org.ldk.enums.*;
 import org.ldk.util.*;
 import java.util.Arrays;
+import javax.annotation.Nullable;
 
 """
         self.c_fn_ty_pfx = "JNIEXPORT "
@@ -451,13 +513,17 @@ import java.util.Arrays;
         self.ptr_native_ty = "long"
         self.result_c_ty = "jclass"
         self.ptr_arr = "jobjectArray"
+        self.is_arr_some_check = ("", " != NULL")
         self.get_native_arr_len_call = ("(*env)->GetArrayLength(env, ", ")")
 
     def construct_jenv(self):
         res =  "JNIEnv *env;\n"
         res += "jint get_jenv_res = (*j_calls->vm)->GetEnv(j_calls->vm, (void**)&env, JNI_VERSION_1_6);\n"
         res += "if (get_jenv_res == JNI_EDETACHED) {\n"
-        res += "\tDO_ASSERT((*j_calls->vm)->AttachCurrentThread(j_calls->vm, (void**)&env, NULL) == JNI_OK);\n"
+        if self.target == Target.ANDROID:
+            res += "\tDO_ASSERT((*j_calls->vm)->AttachCurrentThread(j_calls->vm, &env, NULL) == JNI_OK);\n"
+        else:
+            res += "\tDO_ASSERT((*j_calls->vm)->AttachCurrentThread(j_calls->vm, (void**)&env, NULL) == JNI_OK);\n"
         res += "} else {\n"
         res += "\tDO_ASSERT(get_jenv_res == JNI_OK);\n"
         res += "}\n"
@@ -674,7 +740,7 @@ import java.util.Arrays;
         java_meths = []
         for fn_line in field_fns:
             java_meth_descr = "("
-            if fn_line.fn_name != "free" and fn_line.fn_name != "clone":
+            if fn_line.fn_name != "free" and fn_line.fn_name != "cloned":
                 out_java = out_java + "\t\t " + fn_line.ret_ty_info.java_ty + " " + fn_line.fn_name + "("
                 java_trait_constr = java_trait_constr + "\t\t\t@Override public " + fn_line.ret_ty_info.java_ty + " " + fn_line.fn_name + "("
                 out_java_trait += "\t\t/**\n\t\t * " + fn_line.docs.replace("\n", "\n\t\t * ") + "\n\t\t */\n"
@@ -767,7 +833,7 @@ import java.util.Arrays;
                 # We're a supertrait
                 out_c = out_c + "\t" + var[0] + "_JCalls* " + var[1] + ";\n"
         for fn in field_fns:
-            if fn.fn_name != "free" and fn.fn_name != "clone":
+            if fn.fn_name != "free" and fn.fn_name != "cloned":
                 out_c = out_c + "\tjmethodID " + fn.fn_name + "_meth;\n"
         out_c = out_c + "} " + struct_name + "_JCalls;\n"
 
@@ -783,7 +849,7 @@ import java.util.Arrays;
                 out_c = out_c + "\t}\n}\n"
 
         for idx, fn_line in enumerate(field_fns):
-            if fn_line.fn_name != "free" and fn_line.fn_name != "clone":
+            if fn_line.fn_name != "free" and fn_line.fn_name != "cloned":
                 assert fn_line.ret_ty_info.ty_info.get_full_rust_ty()[1] == ""
                 out_c = out_c + fn_line.ret_ty_info.ty_info.get_full_rust_ty()[0] + " " + fn_line.fn_name + "_" + struct_name + "_jcall("
                 if fn_line.self_is_const:
@@ -809,10 +875,13 @@ import java.util.Arrays;
                     out_c = out_c + "\t" + fn_line.ret_ty_info.c_ty + " ret = (*env)->CallObjectMethod(env, obj, j_calls->" + fn_line.fn_name + "_meth"
                 elif fn_line.ret_ty_info.c_ty == "void":
                     out_c += "\t(*env)->Call" + fn_line.ret_ty_info.java_ty.title() + "Method(env, obj, j_calls->" + fn_line.fn_name + "_meth"
+                elif fn_line.ret_ty_info.java_ty == "String":
+                    # Manually write out String methods as they're just an Object
+                    out_c += "\t" + fn_line.ret_ty_info.c_ty + " ret = (*env)->CallObjectMethod(env, obj, j_calls->" + fn_line.fn_name + "_meth"
                 elif not fn_line.ret_ty_info.passed_as_ptr:
                     out_c += "\t" + fn_line.ret_ty_info.c_ty + " ret = (*env)->Call" + fn_line.ret_ty_info.java_ty.title() + "Method(env, obj, j_calls->" + fn_line.fn_name + "_meth"
                 else:
-                    out_c = out_c + "\t" + fn_line.ret_ty_info.rust_obj + "* ret = (" + fn_line.ret_ty_info.rust_obj + "*)(*env)->CallLongMethod(env, obj, j_calls->" + fn_line.fn_name + "_meth"
+                    out_c = out_c + "\tuint64_t ret = (*env)->CallLongMethod(env, obj, j_calls->" + fn_line.fn_name + "_meth"
 
                 for idx, arg_info in enumerate(fn_line.args_ty):
                     if arg_info.ret_conv is not None:
@@ -820,6 +889,12 @@ import java.util.Arrays;
                     else:
                         out_c = out_c + ", " + arg_info.arg_name
                 out_c = out_c + ");\n"
+
+                out_c += "\tif ((*env)->ExceptionCheck(env)) {\n"
+                out_c += "\t\t(*env)->ExceptionDescribe(env);\n"
+                out_c += "\t\t(*env)->FatalError(env, \"A call to " + fn_line.fn_name + " in " + struct_name + " from rust threw an exception.\");\n"
+                out_c += "\t}\n"
+
                 if fn_line.ret_ty_info.arg_conv is not None:
                     out_c += "\t" + fn_line.ret_ty_info.arg_conv.replace("\n", "\n\t") + "\n"
                     out_c += "\t" + self.deconstruct_jenv().replace("\n", "\n\t").strip() + "\n"
@@ -831,15 +906,19 @@ import java.util.Arrays;
 
                 out_c = out_c + "}\n"
 
-        # Write out a clone function whether we need one or not, as we use them in moving to rust
-        out_c = out_c + "static void* " + struct_name + "_JCalls_clone(const void* this_arg) {\n"
-        out_c = out_c + "\t" + struct_name + "_JCalls *j_calls = (" + struct_name + "_JCalls*) this_arg;\n"
-        out_c = out_c + "\tatomic_fetch_add_explicit(&j_calls->refcnt, 1, memory_order_release);\n"
+        # If we can, write out a clone function whether we need one or not, as we use them in moving to rust
+        can_clone_with_ptr = True
         for var in field_vars:
-            if not isinstance(var, ConvInfo):
-                out_c = out_c + "\tatomic_fetch_add_explicit(&j_calls->" + var[1] + "->refcnt, 1, memory_order_release);\n"
-        out_c = out_c + "\treturn (void*) this_arg;\n"
-        out_c = out_c + "}\n"
+            if isinstance(var, ConvInfo):
+                can_clone_with_ptr = False
+        if can_clone_with_ptr:
+            out_c = out_c + "static void " + struct_name + "_JCalls_cloned(" + struct_name + "* new_obj) {\n"
+            out_c = out_c + "\t" + struct_name + "_JCalls *j_calls = (" + struct_name + "_JCalls*) new_obj->this_arg;\n"
+            out_c = out_c + "\tatomic_fetch_add_explicit(&j_calls->refcnt, 1, memory_order_release);\n"
+            for var in field_vars:
+                if not isinstance(var, ConvInfo):
+                    out_c = out_c + "\tatomic_fetch_add_explicit(&j_calls->" + var[1] + "->refcnt, 1, memory_order_release);\n"
+            out_c = out_c + "}\n"
 
         out_c = out_c + "static inline " + struct_name + " " + struct_name + "_init (" + self.c_fn_args_pfx + ", jobject o"
         for var in flattened_field_vars:
@@ -857,7 +936,7 @@ import java.util.Arrays;
         out_c = out_c + "\tcalls->o = (*env)->NewWeakGlobalRef(env, o);\n"
 
         for (fn_name, java_meth_descr) in java_meths:
-            if fn_name != "free" and fn_name != "clone":
+            if fn_name != "free" and fn_name != "cloned":
                 out_c = out_c + "\tcalls->" + fn_name + "_meth = (*env)->GetMethodID(env, c, \"" + fn_name + "\", \"" + java_meth_descr + "\");\n"
                 out_c = out_c + "\tCHECK(calls->" + fn_name + "_meth != NULL);\n"
 
@@ -867,12 +946,12 @@ import java.util.Arrays;
         out_c = out_c + "\n\t" + struct_name + " ret = {\n"
         out_c = out_c + "\t\t.this_arg = (void*) calls,\n"
         for fn_line in field_fns:
-            if fn_line.fn_name != "free" and fn_line.fn_name != "clone":
+            if fn_line.fn_name != "free" and fn_line.fn_name != "cloned":
                 out_c = out_c + "\t\t." + fn_line.fn_name + " = " + fn_line.fn_name + "_" + struct_name + "_jcall,\n"
             elif fn_line.fn_name == "free":
                 out_c = out_c + "\t\t.free = " + struct_name + "_JCalls_free,\n"
             else:
-                out_c = out_c + "\t\t.clone = " + struct_name + "_JCalls_clone,\n"
+                out_c = out_c + "\t\t.cloned = " + struct_name + "_JCalls_cloned,\n"
         for var in field_vars:
             if isinstance(var, ConvInfo):
                 if var.arg_conv_name is not None:
@@ -914,12 +993,34 @@ import java.util.Arrays;
         out_c = out_c + "\treturn (uint64_t)res_ptr;\n"
         out_c = out_c + "}\n"
 
+        for var in flattened_field_vars:
+            if not isinstance(var, ConvInfo):
+                out_java_trait += "\n\t/**\n"
+                out_java_trait += "\t * Gets the underlying " + var[1] + ".\n"
+                out_java_trait += "\t */\n"
+                underscore_name = ''.join('_' + c.lower() if c.isupper() else c for c in var[1]).strip('_')
+                out_java_trait += "\tpublic " + var[1] + " get_" + underscore_name + "() {\n"
+                out_java_trait += "\t\t" + var[1] + " res = new " + var[1] + "(null, bindings." + struct_name + "_get_" + var[1] + "(this.ptr));\n"
+                out_java_trait += "\t\tthis.ptrs_to.add(res);\n"
+                out_java_trait += "\t\treturn res;\n"
+                out_java_trait += "\t}\n"
+                out_java_trait += "\n"
+
+                out_java += "\tpublic static native long " + struct_name + "_get_" + var[1] + "(long arg);\n"
+
+                out_c += "JNIEXPORT int64_t JNICALL Java_org_ldk_impl_bindings_" + struct_name + "_1get_1" + var[1] + "(JNIEnv *env, jclass clz, int64_t arg) {\n"
+                out_c += "\t" + struct_name + " *inp = (" + struct_name + " *)(arg & ~1);\n"
+                out_c += "\tuint64_t res_ptr = (uint64_t)&inp->" + var[1] + ";\n"
+                out_c += "\tDO_ASSERT((res_ptr & 1) == 0);\n"
+                out_c += "\treturn (int64_t)(res_ptr | 1);\n"
+                out_c += "}\n"
+
         return (out_java, out_java_trait, out_c)
 
     def trait_struct_inc_refcnt(self, ty_info):
         base_conv = "\nif (" + ty_info.var_name + "_conv.free == " + ty_info.rust_obj + "_JCalls_free) {\n"
         base_conv = base_conv + "\t// If this_arg is a JCalls struct, then we need to increment the refcnt in it.\n"
-        base_conv = base_conv + "\t" + ty_info.rust_obj + "_JCalls_clone(" + ty_info.var_name + "_conv.this_arg);\n}"
+        base_conv = base_conv + "\t" + ty_info.rust_obj + "_JCalls_cloned(&" + ty_info.var_name + "_conv);\n}"
         return base_conv
 
     def map_complex_enum(self, struct_name, variant_list, camel_to_snake, enum_doc_comment):
@@ -955,7 +1056,7 @@ import java.util.Arrays;
             init_meth_params = ""
             init_meth_body = ""
             hu_conv_body = ""
-            for idx, field_ty in enumerate(var.fields):
+            for idx, (field_ty, field_docs) in enumerate(var.fields):
                 if idx > 0:
                     init_meth_params = init_meth_params + ", "
 
@@ -966,7 +1067,12 @@ import java.util.Arrays;
                     init_meth_params = init_meth_params + field_path + " " + field_ty.arg_name
                 else:
                     out_java += "\t\t\tpublic " + field_ty.java_ty + " " + field_ty.arg_name + ";\n"
-                    java_hu_subclasses = java_hu_subclasses + "\t\tpublic final " + field_ty.java_hu_ty + " " + field_ty.arg_name + ";\n"
+                    if field_docs is not None:
+                        java_hu_subclasses += "\t\t/**\n\t\t * " + field_docs.replace("\n", "\n\t\t * ") + "\n\t\t*/\n"
+                    java_hu_subclasses += "\t\t"
+                    if field_ty.nullable:
+                        java_hu_subclasses += "@Nullable "
+                    java_hu_subclasses += "public final " + field_ty.java_hu_ty + " " + field_ty.arg_name + ";\n"
                     init_meth_params = init_meth_params + field_ty.java_ty + " " + field_ty.arg_name
                 init_meth_body = init_meth_body + "this." + field_ty.arg_name + " = " + field_ty.arg_name + "; "
                 if field_ty.to_hu_conv is not None:
@@ -1000,7 +1106,7 @@ import java.util.Arrays;
         for var in variant_list:
             out_c += ("\t\tcase " + struct_name + "_" + var.var_name + ": {\n")
             c_params = []
-            for idx, field_map in enumerate(var.fields):
+            for idx, (field_map, field_docs) in enumerate(var.fields):
                 if field_map.ret_conv is not None:
                     out_c += ("\t\t\t" + field_map.ret_conv[0].replace("\n", "\n\t\t\t"))
                     if var.tuple_variant:
@@ -1025,11 +1131,12 @@ import java.util.Arrays;
         out_opaque_struct_human += self.hu_struct_file_prefix
         out_opaque_struct_human += "\n/**\n * " + struct_doc_comment.replace("\n", "\n * ") + "\n */\n"
         out_opaque_struct_human += "@SuppressWarnings(\"unchecked\") // We correctly assign various generic arrays\n"
-        out_opaque_struct_human += ("public class " + struct_name.replace("LDK","") + " extends CommonBase")
+        hu_name = struct_name.replace("LDKC2Tuple", "TwoTuple").replace("LDKC3Tuple", "ThreeTuple").replace("LDK", "")
+        out_opaque_struct_human += ("public class " + hu_name + " extends CommonBase")
         if struct_name.startswith("LDKLocked"):
             out_opaque_struct_human += (" implements AutoCloseable")
         out_opaque_struct_human += (" {\n")
-        out_opaque_struct_human += ("\t" + struct_name.replace("LDK", "") + "(Object _dummy, long ptr) { super(ptr); }\n")
+        out_opaque_struct_human += ("\t" + hu_name + "(Object _dummy, long ptr) { super(ptr); }\n")
         if struct_name.startswith("LDKLocked"):
             out_opaque_struct_human += ("\t@Override public void close() {\n")
         else:
@@ -1040,8 +1147,10 @@ import java.util.Arrays;
         out_opaque_struct_human += ("\t}\n\n")
         return out_opaque_struct_human
 
+    def map_tuple(self, struct_name):
+        return self.map_opaque_struct(struct_name, "A Tuple")
 
-    def map_function(self, argument_types, c_call_string, method_name, return_type_info, struct_meth, default_constructor_args, takes_self, takes_self_as_ref, args_known, type_mapping_generator, doc_comment):
+    def map_function(self, argument_types, c_call_string, method_name, meth_n, return_type_info, struct_meth, default_constructor_args, takes_self, takes_self_as_ref, args_known, type_mapping_generator, doc_comment):
         out_java = ""
         out_c = ""
         out_java_struct = None
@@ -1068,9 +1177,10 @@ import java.util.Arrays;
         if not args_known:
             out_java_struct += ("\t// Skipped " + method_name + "\n")
         else:
-            meth_n = method_name[len(struct_meth) + 1:].strip("_")
             if doc_comment is not None:
                 out_java_struct += "\t/**\n\t * " + doc_comment.replace("\n", "\n\t * ") + "\n\t */\n"
+            if return_type_info.nullable:
+                out_java_struct += "\t@Nullable\n"
             if not takes_self:
                 if meth_n == "new":
                     out_java_struct += "\tpublic static " + return_type_info.java_hu_ty + " of("
@@ -1088,13 +1198,19 @@ import java.util.Arrays;
                     continue
                 if arg.java_ty != "void":
                     if arg.arg_name in default_constructor_args:
+                        assert not arg.nullable
                         for explode_idx, explode_arg in enumerate(default_constructor_args[arg.arg_name]):
                             if explode_idx != 0:
                                 out_java_struct += (", ")
                             out_java_struct += (
                                 explode_arg.java_hu_ty + " " + arg.arg_name + "_" + explode_arg.arg_name)
                     else:
-                        out_java_struct += (arg.java_hu_ty + " " + arg.arg_name)
+                        if arg.nullable:
+                            out_java_struct += "@Nullable "
+                        ty_string = arg.java_hu_ty
+                        if arg.java_fn_ty_arg[0] == "L" and arg.java_fn_ty_arg[len(arg.java_fn_ty_arg) - 1] == ";":
+                            ty_string = arg.java_fn_ty_arg.strip("L;").replace("/", ".")
+                        out_java_struct += ty_string + " " + arg.arg_name
         out_java += (");\n")
         out_c += (") {\n")
         if out_java_struct is not None:
@@ -1160,6 +1276,9 @@ import java.util.Arrays;
                 else:
                     out_java_struct += (info.arg_name)
             out_java_struct += (");\n")
+            if return_type_info.java_ty == "long" and return_type_info.java_hu_ty != "long":
+                out_java_struct += "\t\tif (ret >= 0 && ret < 1024) { return null; }\n"
+
             if return_type_info.to_hu_conv is not None:
                 if not takes_self:
                     out_java_struct += ("\t\t" + return_type_info.to_hu_conv.replace("\n", "\n\t\t").replace("this",