[libc] Implement ntohl and ntohs

[rtenneti]

Summary

Per spec:

https://pubs.opengroup.org/onlinepubs/9699919799/functions/ntohl.html
https://pubs.opengroup.org/onlinepubs/9699919799/functions/ntohs.html

Co-authored-by: Jeff Bailey <[e-mail]>

[sivachandra]

libc/src/network/ntohl.cpp

16

Should this always convert to big-endian, or should it convert to the host's endianness?

[rtenneti]

libc/src/network/ntohl.cpp

16

I thought of implementing it as the following:

LLVM_LIBC_FUNCTION(uint32_t, ntohl, (uint32_t netlong)) {

return Endian::IS_LITTLE ? __builtin_bswap32(netlong) : netlong;

}

The above seem to be same as Endian::to_big_endian. I am wondering if it is better to implement the above (to be clearer). What do you think? Thanks

[rtenneti]

+ Added explicit check for IS_LITTLE to do the swap.
+ Added a test to verify htonl(ntohl(orig)) == orig.

[rtenneti]

Hi Siva,

Added a htonl(ntohl(...)) test. Did the swap based on host's endianess. PTAL.

[sivachandra]

libc/src/network/ntohl.cpp

16

I think this is cleaner. One more suggestion - use a constexpr if statement like this:

if constexpr (Endian::IS_LITTLE)
  return __builtin_bswap(netlong);
else
  return netlong;

[rtenneti]

Fixed comments.

[rtenneti]

Did a git pull rebase false to merge the latest changes.

[sivachandra]

Not sure what happened here, but the diff is not related to the topic of this change.

[rtenneti]

Ran git restore on llvm files.

[rtenneti]

Dif a git pull --rebase.

[rtenneti]

Fixed comments.

[rtenneti]

Fixing Siva's comments.

libc/config/linux/aarch64/entrypoints.txt

set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.truncl
 )
 
 if(LLVM_LIBC_FULL_BUILD)
   list(APPEND TARGET_LIBC_ENTRYPOINTS
     # network.h entrypoints
     libc.src.network.htonl
     libc.src.network.htons
+    libc.src.network.ntohl
+    libc.src.network.ntohs
 
     # pthread.h entrypoints
     libc.src.pthread.pthread_atfork
     libc.src.pthread.pthread_attr_destroy
     libc.src.pthread.pthread_attr_init
     libc.src.pthread.pthread_attr_getdetachstate
     libc.src.pthread.pthread_attr_getguardsize
     libc.src.pthread.pthread_attr_getstack

libc/config/linux/x86_64/entrypoints.txt

list(APPEND TARGET_LIBC_ENTRYPOINTS
     libc.src.dirent.closedir
     libc.src.dirent.dirfd
     libc.src.dirent.opendir
     libc.src.dirent.readdir
 
     # network.h entrypoints
     libc.src.network.htonl
     libc.src.network.htons
+    libc.src.network.ntohl
+    libc.src.network.ntohs
 
     # pthread.h entrypoints
     libc.src.pthread.pthread_atfork
     libc.src.pthread.pthread_attr_destroy
     libc.src.pthread.pthread_attr_init
     libc.src.pthread.pthread_attr_getdetachstate
     libc.src.pthread.pthread_attr_getguardsize
     libc.src.pthread.pthread_attr_getstack

libc/spec/posix.td

HeaderSpec ArpaInet = HeaderSpec<
               RetValSpec<UInt32Type>,
               [ArgSpec<UInt32Type>]
           >,
           FunctionSpec<
               "htons",
               RetValSpec<UInt16Type>,
               [ArgSpec<UInt16Type>]
           >,
+          FunctionSpec<
+              "ntohl",
+              RetValSpec<UInt32Type>,
+              [ArgSpec<UInt32Type>]
+          >,
+          FunctionSpec<
+              "ntohs",
+              RetValSpec<UInt16Type>,
+              [ArgSpec<UInt16Type>]
+          >,
       ]
   >;
 
   HeaderSpec PThread = HeaderSpec<
     "pthread.h",
     [], // Macros
     [
         AtForkCallbackT,

libc/src/network/CMakeLists.txt

add_entrypoint_object(
   SRCS
     htons.cpp
   HDRS
     htons.h
   DEPENDS
     libc.include.arpa_inet
     libc.src.__support.common
 )
+
+add_entrypoint_object(
+  ntohl
+  SRCS
+    ntohl.cpp
+  HDRS
+    ntohl.h
+  DEPENDS
+    libc.include.arpa_inet
+    libc.src.__support.common
+)
+
+add_entrypoint_object(
+  ntohs
+  SRCS
+    ntohs.cpp
+  HDRS
+    ntohs.h
+  DEPENDS
+    libc.include.arpa_inet
+    libc.src.__support.common
+)

libc/src/network/htons.h

 //===-- Implementation header of htons --------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_LIBC_SRC_NETWORK_HTONS_H
 #define LLVM_LIBC_SRC_NETWORK_HTONS_H
 
 #include <stdint.h>
 
 namespace __llvm_libc {
 
-uint16_t htons(uint16_t hostlong);
+uint16_t htons(uint16_t hostshort);
 
 } // namespace __llvm_libc
 
 #endif // LLVM_LIBC_SRC_NETWORK_HTONS_H

libc/src/network/ntohl.h

-//===-- Implementation header of htons --------------------------*- C++ -*-===//
+//===-- Implementation header of ntohl --------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_LIBC_SRC_NETWORK_HTONS_H
-#define LLVM_LIBC_SRC_NETWORK_HTONS_H
+#ifndef LLVM_LIBC_SRC_NETWORK_NTOHL_H
+#define LLVM_LIBC_SRC_NETWORK_NTOHL_H
 
 #include <stdint.h>
 
 namespace __llvm_libc {
 
-uint16_t htons(uint16_t hostlong);
+uint32_t ntohl(uint32_t netlong);
 
 } // namespace __llvm_libc
 
-#endif // LLVM_LIBC_SRC_NETWORK_HTONS_H
+#endif // LLVM_LIBC_SRC_NETWORK_NTOHL_H

libc/src/network/ntohl.cpp

-//===-- Implementation header of htons --------------------------*- C++ -*-===//
+//===-- Implementation of ntohl function ----------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_LIBC_SRC_NETWORK_HTONS_H
-#define LLVM_LIBC_SRC_NETWORK_HTONS_H
-
-#include <stdint.h>
+#include "src/network/ntohl.h"
+#include "src/__support/common.h"
+#include "src/__support/endian.h"
 
 namespace __llvm_libc {
 
-uint16_t htons(uint16_t hostlong);
+LLVM_LIBC_FUNCTION(uint32_t, ntohl, (uint32_t netlong)) {
+  if constexpr (Endian::IS_LITTLE)
+    return __builtin_bswap32(netlong);
+  else
+    return netlong;
+}
 
 } // namespace __llvm_libc
-
-#endif // LLVM_LIBC_SRC_NETWORK_HTONS_H

libc/src/network/ntohs.h

-//===-- Implementation header of htons --------------------------*- C++ -*-===//
+//===-- Implementation header of ntohs --------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_LIBC_SRC_NETWORK_HTONS_H
-#define LLVM_LIBC_SRC_NETWORK_HTONS_H
+#ifndef LLVM_LIBC_SRC_NETWORK_NTOHS_H
+#define LLVM_LIBC_SRC_NETWORK_NTOHS_H
 
 #include <stdint.h>
 
 namespace __llvm_libc {
 
-uint16_t htons(uint16_t hostlong);
+uint16_t ntohs(uint16_t netshort);
 
 } // namespace __llvm_libc
 
-#endif // LLVM_LIBC_SRC_NETWORK_HTONS_H
+#endif // LLVM_LIBC_SRC_NETWORK_NTOHS_H

libc/src/network/ntohs.cpp

+//===-- Implementation of ntohs function ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/network/ntohs.h"
+#include "src/__support/common.h"
+#include "src/__support/endian.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(uint16_t, ntohs, (uint16_t netshort)) {
+  if constexpr (Endian::IS_LITTLE)
+    return __builtin_bswap16(netshort);
+  else
+    return netshort;
+}
+
+} // namespace __llvm_libc

libc/test/src/network/CMakeLists.txt

 add_libc_testsuite(libc_network_unittests)
 
 add_libc_unittest(
   htonl
   SUITE
     libc_network_unittests
   SRCS
     htonl_test.cpp
   CXX_STANDARD
     20
   DEPENDS
     libc.src.network.htonl
+    libc.src.network.ntohl
 )
 
 add_libc_unittest(
   htons
   SUITE
     libc_network_unittests
   SRCS
     htons_test.cpp
   CXX_STANDARD
     20
   DEPENDS
     libc.src.network.htons
+    libc.src.network.ntohs
+)
+
+add_libc_unittest(
+  ntohl
+  SUITE
+    libc_network_unittests
+  SRCS
+    ntohl_test.cpp
+  CXX_STANDARD
+    20
+  DEPENDS
+    libc.src.network.htonl
+    libc.src.network.ntohl
+)
+
+add_libc_unittest(
+  ntohs
+  SUITE
+    libc_network_unittests
+  SRCS
+    ntohs_test.cpp
+  CXX_STANDARD
+    20
+  DEPENDS
+    libc.src.network.htons
+    libc.src.network.ntohs
 )

libc/test/src/network/htonl_test.cpp

 //===-- Unittests for htonl -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/__support/endian.h"
 #include "src/network/htonl.h"
+#include "src/network/ntohl.h"
 #include "test/UnitTest/Test.h"
 
 TEST(LlvmLibcHtonl, SmokeTest) {
   uint32_t original = 0x67452301;
   uint32_t swapped = 0x01234567;
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
   EXPECT_EQ(__llvm_libc::htonl(original), swapped);
 #endif
 #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
   EXPECT_EQ(__llvm_libc::htonl(original), original);
 #endif
 }
+
+TEST(LlvmLibcHtonl, CompleteTest) {
+  uint32_t original = 0x01234567;
+  EXPECT_EQ(__llvm_libc::htonl(__llvm_libc::ntohl(original)), original);
+}

libc/test/src/network/htons_test.cpp

 //===-- Unittests for htons -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/__support/endian.h"
 #include "src/network/htons.h"
+#include "src/network/ntohs.h"
 #include "test/UnitTest/Test.h"
 
 TEST(LlvmLibcHtons, SmokeTest) {
   uint16_t original = 0x2301;
   uint16_t swapped = 0x0123;
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
   EXPECT_EQ(__llvm_libc::htons(original), swapped);
 #endif
 #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
   EXPECT_EQ(__llvm_libc::htons(original), original);
 #endif
 }
+
+TEST(LlvmLibcHtons, CompleteTest) {
+  uint16_t original = 0x0123;
+  EXPECT_EQ(__llvm_libc::htons(__llvm_libc::ntohs(original)), original);
+}

libc/test/src/network/ntohl_test.cpp

-//===-- Unittests for htonl -----------------------------------------------===//
+//===-- Unittests for ntohl -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/__support/endian.h"
 #include "src/network/htonl.h"
+#include "src/network/ntohl.h"
 #include "test/UnitTest/Test.h"
 
-TEST(LlvmLibcHtonl, SmokeTest) {
+TEST(LlvmLibcNtohl, SmokeTest) {
   uint32_t original = 0x67452301;
   uint32_t swapped = 0x01234567;
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-  EXPECT_EQ(__llvm_libc::htonl(original), swapped);
+  EXPECT_EQ(__llvm_libc::ntohl(original), swapped);
 #endif
 #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
-  EXPECT_EQ(__llvm_libc::htonl(original), original);
+  EXPECT_EQ(__llvm_libc::ntohl(original), original);
 #endif
 }
+
+TEST(LlvmLibcNtohl, CompleteTest) {
+  uint32_t original = 0x01234567;
+  EXPECT_EQ(__llvm_libc::ntohl(__llvm_libc::htonl(original)), original);
+}

libc/test/src/network/ntohs_test.cpp

-//===-- Unittests for htons -----------------------------------------------===//
+//===-- Unittests for ntohs -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "src/__support/endian.h"
 #include "src/network/htons.h"
+#include "src/network/ntohs.h"
 #include "test/UnitTest/Test.h"
 
-TEST(LlvmLibcHtons, SmokeTest) {
+TEST(LlvmLibcNtohs, SmokeTest) {
   uint16_t original = 0x2301;
   uint16_t swapped = 0x0123;
 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-  EXPECT_EQ(__llvm_libc::htons(original), swapped);
+  EXPECT_EQ(__llvm_libc::ntohs(original), swapped);
 #endif
 #if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
-  EXPECT_EQ(__llvm_libc::htons(original), original);
+  EXPECT_EQ(__llvm_libc::ntohs(original), original);
 #endif
 }
+
+TEST(LlvmLibcNtohs, CompleteTest) {
+  uint16_t original = 0x0123;
+  EXPECT_EQ(__llvm_libc::ntohs(__llvm_libc::htons(original)), original);
+}