crypto: simplify DH modp group name matcher

* Use ARRAY_SIZE() rather than scanning until we hit a NULL entry.
* Fix `-fsigned-char -Wnarrowing` compiler warnings. Harmless but
  numerous and annoying.
* Static-ify the modp_group and mod_groups arrays.
* Const-ify the modp_groups array.

src/node_crypto.cc

@@ -2972,25 +2972,21 @@ void DiffieHellman::DiffieHellmanGroup(
   }
 
   const String::Utf8Value group_name(args[0]);
+  for (unsigned int i = 0; i < ARRAY_SIZE(modp_groups); ++i) {
+    const modp_group* it = modp_groups + i;
 
-  modp_group* it = modp_groups;
+    if (strcasecmp(*group_name, it->name) != 0)
+      continue;
 
-  while (it->name != NULL) {
-    if (!strcasecmp(*group_name, it->name))
-      break;
-    it++;
-  }
-
-  if (it->name != NULL) {
     diffieHellman->Init(it->prime,
                         it->prime_size,
                         it->gen,
                         it->gen_size);
-  } else {
-    return ThrowError("Unknown group");
+    diffieHellman->Wrap(args.This());
+    return;
   }
 
-  diffieHellman->Wrap(args.This());
+  ThrowError("Unknown group");
 }
 
 

src/node_crypto_groups.h

@@ -7,9 +7,9 @@
 */
 
 
-const char two_generator[] = { 2 };
+static const unsigned char two_generator[] = { 2 };
 
-const char group_modp1[] = {
+static const unsigned char group_modp1[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -21,7 +21,7 @@ const char group_modp1[] = {
   0xf4, 0x4c, 0x42, 0xe9, 0xa6, 0x3a, 0x36, 0x20, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
-const char group_modp2[] = {
+static const unsigned char group_modp2[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -36,7 +36,7 @@ const char group_modp2[] = {
   0x1f, 0xe6, 0x49, 0x28, 0x66, 0x51, 0xec, 0xe6, 0x53, 0x81,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
-const char group_modp5[] = {
+static const unsigned char group_modp5[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -58,7 +58,7 @@ const char group_modp5[] = {
   0xca, 0x23, 0x73, 0x27, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff };
 
-const char group_modp14[] = {
+static const unsigned char group_modp14[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -86,7 +86,7 @@ const char group_modp14[] = {
   0x15, 0x72, 0x8e, 0x5a, 0x8a, 0xac, 0xaa, 0x68, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
-const char group_modp15[] = {
+static const unsigned char group_modp15[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -127,7 +127,7 @@ const char group_modp15[] = {
   0xd1, 0x20, 0xa9, 0x3a, 0xd2, 0xca, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff, 0xff, 0xff };
 
-const char group_modp16[] = {
+static const unsigned char group_modp16[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -181,7 +181,7 @@ const char group_modp16[] = {
   0x34, 0x06, 0x31, 0x99, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
   0xff, 0xff };
 
-const char group_modp17[] = {
+static const unsigned char group_modp17[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -260,7 +260,7 @@ const char group_modp17[] = {
   0x74, 0xd6, 0xe6, 0x94, 0xf9, 0x1e, 0x6d, 0xcc, 0x40, 0x24,
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
-const char group_modp18[] = {
+static const unsigned char group_modp18[] = {
   0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xc9, 0x0f,
   0xda, 0xa2, 0x21, 0x68, 0xc2, 0x34, 0xc4, 0xc6, 0x62, 0x8b,
   0x80, 0xdc, 0x1c, 0xd1, 0x29, 0x02, 0x4e, 0x08, 0x8a, 0x67,
@@ -368,19 +368,20 @@ const char group_modp18[] = {
 typedef struct {
   const char* name;
   const char* prime;
-  int prime_size;
+  unsigned int prime_size;
   const char* gen;
-  int gen_size;
+  unsigned int gen_size;
 } modp_group;
 
-modp_group modp_groups[] = {
-  { "modp1", group_modp1, sizeof(group_modp1) / sizeof(group_modp1[0]), two_generator, 1 },
-  { "modp2", group_modp2, sizeof(group_modp2) / sizeof(group_modp2[0]), two_generator, 1 },
-  { "modp5", group_modp5, sizeof(group_modp5) / sizeof(group_modp5[0]), two_generator, 1 },
-  { "modp14", group_modp14, sizeof(group_modp14) / sizeof(group_modp14[0]), two_generator, 1 },
-  { "modp15", group_modp15, sizeof(group_modp15) / sizeof(group_modp15[0]), two_generator, 1 },
-  { "modp16", group_modp16, sizeof(group_modp16) / sizeof(group_modp16[0]), two_generator, 1 },
-  { "modp17", group_modp17, sizeof(group_modp17) / sizeof(group_modp17[0]), two_generator, 1 },
-  { "modp18", group_modp18, sizeof(group_modp18) / sizeof(group_modp18[0]), two_generator, 1 },
-  { NULL, NULL, 0, NULL, 0 }
+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 }
+#undef V
 };