[libc-commits] [libc] [libc] implement `inet_aton` (PR #162651)
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Thu Oct 9 06:22:12 PDT 2025
https://github.com/c8ef created https://github.com/llvm/llvm-project/pull/162651
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>From 9774e2daaa5e89c6684f91b82ab5b4b5c6b88c88 Mon Sep 17 00:00:00 2001
From: c8ef <c8ef at outlook.com>
Date: Thu, 9 Oct 2025 21:21:09 +0800
Subject: [PATCH] [libc] implement inet_aton
---
libc/config/linux/aarch64/entrypoints.txt | 1 +
libc/config/linux/riscv/entrypoints.txt | 1 +
libc/config/linux/x86_64/entrypoints.txt | 1 +
libc/include/arpa/inet.yaml | 10 ++-
libc/src/arpa/inet/CMakeLists.txt | 14 ++++
libc/src/arpa/inet/inet_aton.cpp | 63 +++++++++++++++
libc/src/arpa/inet/inet_aton.h | 21 +++++
libc/test/src/arpa/inet/CMakeLists.txt | 13 +++
libc/test/src/arpa/inet/inet_aton_test.cpp | 93 ++++++++++++++++++++++
9 files changed, 216 insertions(+), 1 deletion(-)
create mode 100644 libc/src/arpa/inet/inet_aton.cpp
create mode 100644 libc/src/arpa/inet/inet_aton.h
create mode 100644 libc/test/src/arpa/inet/inet_aton_test.cpp
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 8bf6c44b1d669..714120a79e39a 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -945,6 +945,7 @@ if(LLVM_LIBC_FULL_BUILD)
# arpa/inet.h entrypoints
libc.src.arpa.inet.htonl
libc.src.arpa.inet.htons
+ libc.src.arpa.inet.inet_aton
libc.src.arpa.inet.ntohl
libc.src.arpa.inet.ntohs
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index dffccbab9a8e9..f6bbb346d10e5 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -1077,6 +1077,7 @@ if(LLVM_LIBC_FULL_BUILD)
# arpa/inet.h entrypoints
libc.src.arpa.inet.htonl
libc.src.arpa.inet.htons
+ libc.src.arpa.inet.inet_aton
libc.src.arpa.inet.ntohl
libc.src.arpa.inet.ntohs
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index b4ab073ec912f..aa455e80ec5d3 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -1113,6 +1113,7 @@ if(LLVM_LIBC_FULL_BUILD)
# arpa/inet.h entrypoints
libc.src.arpa.inet.htonl
libc.src.arpa.inet.htons
+ libc.src.arpa.inet.inet_aton
libc.src.arpa.inet.ntohl
libc.src.arpa.inet.ntohs
diff --git a/libc/include/arpa/inet.yaml b/libc/include/arpa/inet.yaml
index 10cd56d6ce786..edc8b4e52763f 100644
--- a/libc/include/arpa/inet.yaml
+++ b/libc/include/arpa/inet.yaml
@@ -1,7 +1,8 @@
header: arpa/inet.h
header_template: inet.h.def
macros: []
-types: []
+types:
+ - type_name: in_addr
enums: []
objects: []
functions:
@@ -17,6 +18,13 @@ functions:
return_type: uint16_t
arguments:
- type: uint16_t
+ - name: inet_aton
+ standards:
+ - POSIX
+ return_type: int
+ arguments:
+ - type: const char *
+ - type: in_addr *
- name: ntohl
standards:
- POSIX
diff --git a/libc/src/arpa/inet/CMakeLists.txt b/libc/src/arpa/inet/CMakeLists.txt
index 1f39a076fde91..fc17c395a6a24 100644
--- a/libc/src/arpa/inet/CMakeLists.txt
+++ b/libc/src/arpa/inet/CMakeLists.txt
@@ -22,6 +22,20 @@ add_entrypoint_object(
libc.src.__support.common
)
+add_entrypoint_object(
+ inet_aton
+ SRCS
+ inet_aton.cpp
+ HDRS
+ inet_aton.h
+ DEPENDS
+ libc.include.arpa_inet
+ libc.include.llvm-libc-types.in_addr
+ libc.src.__support.common
+ libc.src.__support.str_to_integer
+ libc.src.arpa.inet.htonl
+)
+
add_entrypoint_object(
ntohl
SRCS
diff --git a/libc/src/arpa/inet/inet_aton.cpp b/libc/src/arpa/inet/inet_aton.cpp
new file mode 100644
index 0000000000000..183b147cc0c10
--- /dev/null
+++ b/libc/src/arpa/inet/inet_aton.cpp
@@ -0,0 +1,63 @@
+//===-- Implementation of inet_aton 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/arpa/inet/inet_aton.h"
+#include "src/__support/common.h"
+#include "src/__support/str_to_integer.h"
+#include "src/arpa/inet/htonl.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, inet_aton, (const char *cp, in_addr *inp)) {
+ unsigned long parts[4] = {0};
+ int dot_num = 0;
+
+ for (; dot_num < 4; ++dot_num) {
+ auto result = internal::strtointeger<unsigned long>(cp, 0);
+ parts[dot_num] = result;
+
+ if (result.has_error() || result.parsed_len == 0)
+ return 0;
+ char next_char = *(cp + result.parsed_len);
+ if (next_char != '.' && next_char != '\0')
+ return 0;
+ else if (next_char == '\0')
+ break;
+ else
+ cp += (result.parsed_len + 1);
+ }
+
+ unsigned long result = 0;
+ if (dot_num == 0) {
+ if (parts[0] > 0xffffffff)
+ return 0;
+ result = parts[0];
+ } else if (dot_num == 1) {
+ if (parts[0] > 0xff || parts[1] > 0xffffff)
+ return 0;
+ result = (parts[0] << 24) | parts[1];
+ } else if (dot_num == 2) {
+ if (parts[0] > 0xff || parts[1] > 0xff || parts[2] > 0xffff)
+ return 0;
+ result = (parts[0] << 24) | (parts[1] << 16) | parts[2];
+ } else if (dot_num == 3) {
+ if (parts[0] > 0xff || parts[1] > 0xff || parts[2] > 0xff ||
+ parts[3] > 0xff)
+ return 0;
+ result = (parts[0] << 24) | (parts[1] << 16) | (parts[2] << 8) | parts[3];
+ } else {
+ return 0;
+ }
+
+ if (inp)
+ inp->s_addr = LIBC_NAMESPACE::htonl(static_cast<uint32_t>(result));
+
+ return 1;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/arpa/inet/inet_aton.h b/libc/src/arpa/inet/inet_aton.h
new file mode 100644
index 0000000000000..ea387d1f6b2f6
--- /dev/null
+++ b/libc/src/arpa/inet/inet_aton.h
@@ -0,0 +1,21 @@
+//===-- Implementation header of inet_aton ----------------------*- 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_ARPA_INET_INET_ATON_H
+#define LLVM_LIBC_SRC_ARPA_INET_INET_ATON_H
+
+#include "include/llvm-libc-types/in_addr.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int inet_aton(const char *cp, in_addr *inp);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_ARPA_INET_INET_ATON_H
diff --git a/libc/test/src/arpa/inet/CMakeLists.txt b/libc/test/src/arpa/inet/CMakeLists.txt
index 6e78e3a50e612..42fa49fe07267 100644
--- a/libc/test/src/arpa/inet/CMakeLists.txt
+++ b/libc/test/src/arpa/inet/CMakeLists.txt
@@ -26,6 +26,19 @@ add_libc_unittest(
libc.src.arpa.inet.ntohs
)
+add_libc_unittest(
+ inet_aton
+ SUITE
+ libc_arpa_inet_unittests
+ SRCS
+ inet_aton_test.cpp
+ CXX_STANDARD
+ 20
+ DEPENDS
+ libc.src.arpa.inet.htonl
+ libc.src.arpa.inet.inet_aton
+)
+
add_libc_unittest(
ntohl
SUITE
diff --git a/libc/test/src/arpa/inet/inet_aton_test.cpp b/libc/test/src/arpa/inet/inet_aton_test.cpp
new file mode 100644
index 0000000000000..0b438740b99b0
--- /dev/null
+++ b/libc/test/src/arpa/inet/inet_aton_test.cpp
@@ -0,0 +1,93 @@
+//===-- Unittests for inet_aton -------------------------------------------===//
+//
+// 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/arpa/inet/htonl.h"
+#include "src/arpa/inet/inet_aton.h"
+#include "test/UnitTest/Test.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+TEST(LlvmLibcInetAton, ValidTest) {
+ in_addr a;
+
+ // a.b.c.d
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("127.1.2.4", &a));
+ ASSERT_EQ(htonl(0x7f010204), a.s_addr);
+
+ // a.b.c
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("127.1.4", &a));
+ ASSERT_EQ(htonl(0x7f010004), a.s_addr);
+
+ // a.b
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("127.1", &a));
+ ASSERT_EQ(htonl(0x7f000001), a.s_addr);
+
+ // a
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("0x7f000001", &a));
+ ASSERT_EQ(htonl(0x7f000001), a.s_addr);
+
+ // Hex (0x) and mixed-case hex digits.
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("0xFf.0.0.1", &a));
+ ASSERT_EQ(htonl(0xff000001), a.s_addr);
+
+ // Hex (0X) and mixed-case hex digits.
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("0XfF.0.0.1", &a));
+ ASSERT_EQ(htonl(0xff000001), a.s_addr);
+
+ // Octal.
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("0177.0.0.1", &a));
+ ASSERT_EQ(htonl(0x7f000001), a.s_addr);
+
+ a.s_addr = 0;
+ ASSERT_EQ(1, inet_aton("036", &a));
+ ASSERT_EQ(htonl(036U), a.s_addr);
+}
+
+TEST(LlvmLibcInetAton, InvalidTest) {
+ ASSERT_EQ(0, inet_aton("", nullptr)); // Empty.
+ ASSERT_EQ(0, inet_aton("x", nullptr)); // Leading junk.
+ ASSERT_EQ(0, inet_aton("127.0.0.1x", nullptr)); // Trailing junk.
+ ASSERT_EQ(0, inet_aton("09.0.0.1", nullptr)); // Invalid octal.
+ ASSERT_EQ(0, inet_aton("0xg.0.0.1", nullptr)); // Invalid hex.
+
+ ASSERT_EQ(0, inet_aton("1.2.3.4.5", nullptr)); // Too many dots.
+ ASSERT_EQ(0, inet_aton("1.2.3.4.", nullptr)); // Trailing dot.
+
+ // Out of range a.b.c.d form.
+ ASSERT_EQ(0, inet_aton("999.0.0.1", nullptr));
+ ASSERT_EQ(0, inet_aton("0.999.0.1", nullptr));
+ ASSERT_EQ(0, inet_aton("0.0.999.1", nullptr));
+ ASSERT_EQ(0, inet_aton("0.0.0.999", nullptr));
+
+ // Out of range a.b.c form.
+ ASSERT_EQ(0, inet_aton("256.0.0", nullptr));
+ ASSERT_EQ(0, inet_aton("0.256.0", nullptr));
+ ASSERT_EQ(0, inet_aton("0.0.0x10000", nullptr));
+
+ // Out of range a.b form.
+ ASSERT_EQ(0, inet_aton("256.0", nullptr));
+ ASSERT_EQ(0, inet_aton("0.0x1000000", nullptr));
+
+ // Out of range a form.
+ ASSERT_EQ(0, inet_aton("0x100000000", nullptr));
+
+ // 64-bit overflow.
+ ASSERT_EQ(0, inet_aton("0x10000000000000000", nullptr));
+
+ // Out of range octal.
+ ASSERT_EQ(0, inet_aton("0400.0.0.1", nullptr));
+}
+
+} // namespace LIBC_NAMESPACE_DECL
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