https://github.com/gdelugre/literal_ipaddr
C++17 constexpr implementation of inet_addr / inet_aton / inet_pton
https://github.com/gdelugre/literal_ipaddr
constexpr cxx17 ipaddress
Last synced: about 1 month ago
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C++17 constexpr implementation of inet_addr / inet_aton / inet_pton
- Host: GitHub
- URL: https://github.com/gdelugre/literal_ipaddr
- Owner: gdelugre
- License: mit
- Created: 2019-05-29T17:18:53.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2019-05-29T19:32:55.000Z (over 6 years ago)
- Last Synced: 2025-04-23T21:11:24.455Z (6 months ago)
- Topics: constexpr, cxx17, ipaddress
- Language: C++
- Size: 7.81 KB
- Stars: 27
- Watchers: 2
- Forks: 3
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Parsing IP addresses at compile-time in C++
This repository contains a C++17 constexpr implementation of the IP address parsing functions ``inet_addr``, ``inet_aton`` and ``inet_pton``. It supports both v4 and v6 address families.
When passed a literal IP address string, the compiler will parse the string and generate automatically the ``in_addr`` or ``in6_addr`` structure.
The address format is compatible with standard representations:
- ``inet_addr`` and ``inet_aton`` accept IPv4 addresses in format ``a.b.c.d``, ``a.b.c``, ``a.b``, or ``a``, with address components expressed in decimal, octal or hexadecimal.
```c++
// Alternative syntaxes producing the same result:
// IPAddr::inet_addr("127.0.1")
// IPAddr::inet_addr("127.1")
// IPAddr::inet_addr("0x7f.1")
// IPAddr::inet_addr("2130706433")
//
constexpr in_addr_t addr = IPAddr::inet_addr("127.0.0.1");
```
- ``inet_pton`` supports IPv4 addresses in canonical form (4 decimal components with no leading zeros) and IPv6 addresses represented according to RFC 2373, including with embedded IPv4 addresses.
```c++
constexpr auto in_addr1 = IPAddr::inet_pton("127.0.0.1");
constexpr auto in_addr2 = IPAddr::inet_pton("::1");
constexpr auto in_addr3 = IPAddr::inet_pton("fe80::127.0.0.1"); // IPv4-in-IPv6 syntax
```
The ``ipaddr.h`` header also defines ``_ipaddr`` and ``_ipport`` literals. The ``_ipaddr`` suffix will automatically detect the format of the IP address and return the according ``in[6]_addr`` structure, or raise a static assertion if the format is incorrect.
## Example
```c++
int s = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
const struct sockaddr_in dst {
.sin_family = AF_INET,
.sin_port = 1234_ipport,
.sin_addr = "127.0.0.1"_ipaddr
};
connect(s, (struct sockaddr *)&dst, sizeof(dst));
```
The above example, with clang 8.0.0 on Linux x86_64, generates:
```objdump
mov $0x2,%edi
mov $0x1,%esi
xor %edx,%edx
callq
movups 0xe7e(%rip),%xmm0 # sockaddr in rodata section
mov %rsp,%rsi
movaps %xmm0,(%rsi)
mov %eax,%edi
mov $0x10,%edx
callq
```
With gcc 8.3.0:
```objdump
xor %edx,%edx
mov $0x1,%esi
mov $0x2,%edi
callq
mov $0x10,%edx
lea 0x8(%rsp),%rsi
movabs $0x100007fd2040002,%rcx # sockaddr as an immediate operand
mov %eax,%edi
mov %rcx,0x8(%rsp)
movq $0x0,0x10(%rsp)
callq
```
## License
Distributed under the MIT license, see LICENSE file.