src: don't use locale-sensitive strcasecmp()

strcasecmp() is affected by the current locale as configured through
e.g. the LC_ALL environment variable and the setlocale() libc function.
It can result in unpredictable results across systems so replace it with
a function that isn't susceptible to that.
PR-URL: #6582
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: bnoordhuis

src/node.cc

@@ -69,7 +69,6 @@
 #if defined(_MSC_VER)
 #include<direct.h>
 #include<io.h>
-#definestrcasecmp _stricmp
 #definegetpid GetCurrentProcessId
 #defineumask _umask
 typedefintmode_t;
@@ -1381,27 +1380,27 @@ enum encoding ParseEncoding(const char* encoding,
 break;
  }
 
-if (strcasecmp(encoding, "utf8") == 0) {
+if (StringEqualNoCase(encoding, "utf8")) {
 returnUTF8;
- } elseif (strcasecmp(encoding, "utf-8") == 0) {
+ } elseif (StringEqualNoCase(encoding, "utf-8")) {
 returnUTF8;
- } elseif (strcasecmp(encoding, "ascii") == 0) {
+ } elseif (StringEqualNoCase(encoding, "ascii")) {
 returnASCII;
- } elseif (strcasecmp(encoding, "base64") == 0) {
+ } elseif (StringEqualNoCase(encoding, "base64")) {
 returnBASE64;
- } elseif (strcasecmp(encoding, "ucs2") == 0) {
+ } elseif (StringEqualNoCase(encoding, "ucs2")) {
 returnUCS2;
- } elseif (strcasecmp(encoding, "ucs-2") == 0) {
+ } elseif (StringEqualNoCase(encoding, "ucs-2")) {
 returnUCS2;
- } elseif (strcasecmp(encoding, "utf16le") == 0) {
+ } elseif (StringEqualNoCase(encoding, "utf16le")) {
 returnUCS2;
- } elseif (strcasecmp(encoding, "utf-16le") == 0) {
+ } elseif (StringEqualNoCase(encoding, "utf-16le")) {
 returnUCS2;
- } elseif (strcasecmp(encoding, "binary") == 0) {
+ } elseif (StringEqualNoCase(encoding, "binary")) {
 returnBINARY;
- } elseif (strcasecmp(encoding, "buffer") == 0) {
+ } elseif (StringEqualNoCase(encoding, "buffer")) {
 returnBUFFER;
- } elseif (strcasecmp(encoding, "hex") == 0) {
+ } elseif (StringEqualNoCase(encoding, "hex")) {
 returnHEX;
  } else {
 return default_encoding;

src/node_crypto.cc

@@ -24,10 +24,6 @@
 #include<stdlib.h>
 #include<string.h>
 
-#if defined(_MSC_VER)
-#definestrcasecmp _stricmp
-#endif
-
 #defineTHROW_AND_RETURN_IF_NOT_STRING_OR_BUFFER(val, prefix) \
 do { \
 if (!Buffer::HasInstance(val) && !val->IsString()) { \
@@ -4446,7 +4442,7 @@ void DiffieHellman::DiffieHellmanGroup(
 for (size_t i = 0; i < arraysize(modp_groups); ++i) {
 const modp_group* it = modp_groups + i;
 
-if (strcasecmp(*group_name, it->name) != 0)
+if (!StringEqualNoCase(*group_name, it->name))
 continue;
 
  initialized = diffieHellman->Init(it->prime,

src/util-inl.h

@@ -203,7 +203,19 @@ void SwapBytes(uint16_t* dst, const uint16_t* src, size_t buflen) {
  dst[i] = (src[i] << 8) | (src[i] >> 8);
 }
 
+charToLower(char c) {
+return c >= 'A' && c <= 'Z' ? c + ('a' - 'A') : c;
+}
 
+boolStringEqualNoCase(constchar* a, constchar* b) {
+do {
+if (*a == '\0')
+return *b == '\0';
+if (*b == '\0')
+return *a == '\0';
+ } while (ToLower(*a++) == ToLower(*b++));
+returnfalse;
+}
 
 } // namespace node
 

src/util.h

@@ -178,6 +178,12 @@ inline TypeName* Unwrap(v8::Local<v8::Object> object);
 
 inlinevoidSwapBytes(uint16_t* dst, constuint16_t* src, size_t buflen);
 
+// tolower() is locale-sensitive. Use ToLower() instead.
+inlinecharToLower(char c);
+
+// strcasecmp() is locale-sensitive. Use StringEqualNoCase() instead.
+inlineboolStringEqualNoCase(constchar* a, constchar* b);
+
 // Allocates an array of member type T. For up to kStackStorageSize items,
 // the stack is used, otherwise malloc().
 template <typename T, size_tkStackStorageSize = 1024>

test/cctest/util.cc

@@ -56,3 +56,21 @@ TEST(UtilTest, ListHead) {
 EXPECT_TRUE(list.IsEmpty());
 EXPECT_FALSE(list.begin() != list.end());
 }
+
+TEST(UtilTest, StringEqualNoCase) {
+using node::StringEqualNoCase;
+EXPECT_FALSE(StringEqualNoCase("a", "b"));
+EXPECT_TRUE(StringEqualNoCase("", ""));
+EXPECT_TRUE(StringEqualNoCase("equal", "equal"));
+EXPECT_TRUE(StringEqualNoCase("equal", "EQUAL"));
+EXPECT_TRUE(StringEqualNoCase("EQUAL", "EQUAL"));
+EXPECT_FALSE(StringEqualNoCase("equal", "equals"));
+EXPECT_FALSE(StringEqualNoCase("equals", "equal"));
+}
+
+TEST(UtilTest, ToLower) {
+using node::ToLower;
+EXPECT_EQ('0', ToLower('0'));
+EXPECT_EQ('a', ToLower('a'));
+EXPECT_EQ('a', ToLower('A'));
+}