crypto: simplify DH groups

PR-URL: #31178
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>

Author: tniessen

src/node_crypto.cc

@@ -5687,6 +5687,13 @@ bool DiffieHellman::Init(const char* p, int p_len, const char* g, int g_len) {
   return VerifyContext();
 }
 
+inline const modp_group* FindDiffieHellmanGroup(const char* name) {
+  for (const modp_group& group : modp_groups) {
+    if (StringEqualNoCase(name, group.name))
+      return &group;
+  }
+  return nullptr;
+}
 
 void DiffieHellman::DiffieHellmanGroup(
     const FunctionCallbackInfo<Value>& args) {
@@ -5702,22 +5709,15 @@ void DiffieHellman::DiffieHellmanGroup(
   bool initialized = false;
 
   const node::Utf8Value group_name(env->isolate(), args[0]);
-  for (size_t i = 0; i < arraysize(modp_groups); ++i) {
-    const modp_group* it = modp_groups + i;
-
-    if (!StringEqualNoCase(*group_name, it->name))
-      continue;
-
-    initialized = diffieHellman->Init(it->prime,
-                                      it->prime_size,
-                                      it->gen,
-                                      it->gen_size);
-    if (!initialized)
-      env->ThrowError("Initialization failed");
-    return;
-  }
+  const modp_group* group = FindDiffieHellmanGroup(*group_name);
+  if (group == nullptr)
+    return env->ThrowError("Unknown group");
 
-  env->ThrowError("Unknown group");
+  initialized = diffieHellman->Init(group->prime,
+                                    group->prime_size,
+                                    group->gen);
+  if (!initialized)
+    env->ThrowError("Initialization failed");
 }
 
 

src/node_crypto_groups.h

@@ -32,7 +32,7 @@
 */
 
 
-static const unsigned char two_generator[] = { 2 };
+static const unsigned int two_generator = 2;
 
 static const unsigned char group_modp1[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
@@ -394,20 +394,19 @@ typedef struct {
   const char* name;
   const char* prime;
   unsigned int prime_size;
-  const char* gen;
-  unsigned int gen_size;
+  unsigned int gen;
 } modp_group;
 
 static const modp_group modp_groups[] = {
 #define V(var) reinterpret_cast<const char*>(var)
-  { "modp1", V(group_modp1), sizeof(group_modp1), V(two_generator), 1 },
-  { "modp2", V(group_modp2), sizeof(group_modp2), V(two_generator), 1 },
-  { "modp5", V(group_modp5), sizeof(group_modp5), V(two_generator), 1 },
-  { "modp14", V(group_modp14), sizeof(group_modp14), V(two_generator), 1 },
-  { "modp15", V(group_modp15), sizeof(group_modp15), V(two_generator), 1 },
-  { "modp16", V(group_modp16), sizeof(group_modp16), V(two_generator), 1 },
-  { "modp17", V(group_modp17), sizeof(group_modp17), V(two_generator), 1 },
-  { "modp18", V(group_modp18), sizeof(group_modp18), V(two_generator), 1 }
+  { "modp1", V(group_modp1), sizeof(group_modp1), two_generator },
+  { "modp2", V(group_modp2), sizeof(group_modp2), two_generator },
+  { "modp5", V(group_modp5), sizeof(group_modp5), two_generator },
+  { "modp14", V(group_modp14), sizeof(group_modp14), two_generator },
+  { "modp15", V(group_modp15), sizeof(group_modp15), two_generator },
+  { "modp16", V(group_modp16), sizeof(group_modp16), two_generator },
+  { "modp17", V(group_modp17), sizeof(group_modp17), two_generator },
+  { "modp18", V(group_modp18), sizeof(group_modp18), two_generator }
 #undef V
 };