[libc-commits] [libc] e071e43 - [libc] Add `IN6_IS_ADDR_V4MAPPED` (#172645)

[via libc-commits]

Author: Connector Switch
Date: 2025-12-18T23:12:49+08:00
New Revision: e071e435893d3165a607e0b649ea379d75d86a6e

URL: https://github.com/llvm/llvm-project/commit/e071e435893d3165a607e0b649ea379d75d86a6e
DIFF: https://github.com/llvm/llvm-project/commit/e071e435893d3165a607e0b649ea379d75d86a6e.diff

LOG: [libc] Add `IN6_IS_ADDR_V4MAPPED` (#172645)

This patch adds the `IN6_IS_ADDR_V4MAPPED` macro, which checks whether
an address is IPv4 mapped address.

Added: 
    

Modified: 
    libc/include/llvm-libc-macros/netinet-in-macros.h
    libc/test/include/netinet_in_test.cpp

Removed: 
    


################################################################################
diff  --git a/libc/include/llvm-libc-macros/netinet-in-macros.h b/libc/include/llvm-libc-macros/netinet-in-macros.h
index 88ffe92756b16..1d7bef833f2b8 100644
--- a/libc/include/llvm-libc-macros/netinet-in-macros.h
+++ b/libc/include/llvm-libc-macros/netinet-in-macros.h
@@ -64,6 +64,14 @@
   ((__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[0]) == 0xfe &&            \
    (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xc0) == 0xc0)
 
+#define IN6_IS_ADDR_V4MAPPED(a)                                                \
+  ((__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[0]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint32_t *, a)[1]) == 0 &&              \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[8]) == 0 &&               \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[9]) == 0 &&               \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[10]) == 0xff &&           \
+   (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[11]) == 0xff)
+
 #define IN6_IS_ADDR_MC_NODELOCAL(a)                                            \
   (IN6_IS_ADDR_MULTICAST(a) &&                                                 \
    (__LLVM_LIBC_CAST(reinterpret_cast, uint8_t *, a)[1] & 0xf) == 0x1)

diff  --git a/libc/test/include/netinet_in_test.cpp b/libc/test/include/netinet_in_test.cpp
index 72500c4d51438..2f57080ef8b77 100644
--- a/libc/test/include/netinet_in_test.cpp
+++ b/libc/test/include/netinet_in_test.cpp
@@ -56,4 +56,11 @@ TEST(LlvmLibcNetinetInTest, IN6Macro) {
   EXPECT_TRUE(IN6_IS_ADDR_MC_GLOBAL(buff));
   buff[1] = 0;
   buff[0] = 0;
+
+  EXPECT_FALSE(IN6_IS_ADDR_V4MAPPED(buff));
+  buff[10] = 0xff;
+  buff[11] = 0xff;
+  EXPECT_TRUE(IN6_IS_ADDR_V4MAPPED(buff));
+  buff[10] = 0;
+  buff[11] = 0;
 }