include/boost/corosio/native/detail/endpoint_convert.hpp

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endpoint_convert.hpp

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1			//
2			// Copyright (c) 2026 Vinnie Falco ([email protected])
3			//
4			// Distributed under the Boost Software License, Version 1.0. (See accompanying
5			// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6			//
7			// Official repository: https://github.com/cppalliance/corosio
8			//
9
10			#ifndef BOOST_COROSIO_NATIVE_DETAIL_ENDPOINT_CONVERT_HPP
11			#define BOOST_COROSIO_NATIVE_DETAIL_ENDPOINT_CONVERT_HPP
12
13			#include <boost/corosio/endpoint.hpp>
14			#include <boost/corosio/local_endpoint.hpp>
15			#include <boost/corosio/detail/platform.hpp>
16
17			#include <algorithm>
18			#include <cstring>
19
20			#if BOOST_COROSIO_POSIX
21			#include <sys/socket.h>
22			#include <sys/un.h>
23			#include <netinet/in.h>
24			#include <arpa/inet.h>
25			#else
26			#ifndef WIN32_LEAN_AND_MEAN
27			#define WIN32_LEAN_AND_MEAN
28			#endif
29			#ifndef NOMINMAX
30			#define NOMINMAX
31			#endif
32			#include <WinSock2.h>
33			#include <Ws2tcpip.h>
34			#endif
35
36			#include <cstddef> // offsetof
37
38			#ifndef AF_UNIX
39			#define AF_UNIX 1
40			#endif
41
42			namespace boost::corosio::detail {
43
44			/** Convert IPv4 endpoint to sockaddr_in.
45
46			@param ep The endpoint to convert. Must be IPv4 (is_v4() == true).
47			@return A sockaddr_in structure with fields in network byte order.
48			*/
49			inline sockaddr_in
50		3974x	to_sockaddr_in(endpoint const& ep) noexcept
51			{
52		3974x	sockaddr_in sa{};
53		3974x	sa.sin_family = AF_INET;
54		3974x	sa.sin_port = htons(ep.port());
55		3974x	auto bytes = ep.v4_address().to_bytes();
56		3974x	std::memcpy(&sa.sin_addr, bytes.data(), 4);
57		3974x	return sa;
58			}
59
60			/** Convert IPv6 endpoint to sockaddr_in6.
61
62			@param ep The endpoint to convert. Must be IPv6 (is_v6() == true).
63			@return A sockaddr_in6 structure with fields in network byte order.
64			*/
65			inline sockaddr_in6
66		27x	to_sockaddr_in6(endpoint const& ep) noexcept
67			{
68		27x	sockaddr_in6 sa{};
69		27x	sa.sin6_family = AF_INET6;
70		27x	sa.sin6_port = htons(ep.port());
71		27x	auto bytes = ep.v6_address().to_bytes();
72		27x	std::memcpy(&sa.sin6_addr, bytes.data(), 16);
73		27x	return sa;
74			}
75
76			/** Create endpoint from sockaddr_in.
77
78			@param sa The sockaddr_in structure with fields in network byte order.
79			@return An endpoint with address and port extracted from sa.
80			*/
81			inline endpoint
82		7748x	from_sockaddr_in(sockaddr_in const& sa) noexcept
83			{
84			ipv4_address::bytes_type bytes;
85		7748x	std::memcpy(bytes.data(), &sa.sin_addr, 4);
86		7748x	return endpoint(ipv4_address(bytes), ntohs(sa.sin_port));
87			}
88
89			/** Create endpoint from sockaddr_in6.
90
91			@param sa The sockaddr_in6 structure with fields in network byte order.
92			@return An endpoint with address and port extracted from sa.
93			*/
94			inline endpoint
95		58x	from_sockaddr_in6(sockaddr_in6 const& sa) noexcept
96			{
97			ipv6_address::bytes_type bytes;
98		58x	std::memcpy(bytes.data(), &sa.sin6_addr, 16);
99		58x	return endpoint(ipv6_address(bytes), ntohs(sa.sin6_port));
100			}
101
102			/** Convert an IPv4 endpoint to an IPv4-mapped IPv6 sockaddr_in6.
103
104			Produces a `sockaddr_in6` with the `::ffff:` prefix, suitable
105			for passing an IPv4 destination to a dual-stack IPv6 socket.
106
107			@param ep The endpoint to convert. Must be IPv4 (is_v4() == true).
108			@return A sockaddr_in6 with the IPv4-mapped address.
109			*/
110			inline sockaddr_in6
111		1x	to_v4_mapped_sockaddr_in6(endpoint const& ep) noexcept
112			{
113		1x	sockaddr_in6 sa{};
114		1x	sa.sin6_family = AF_INET6;
115		1x	sa.sin6_port = htons(ep.port());
116			// ::ffff:0:0/96 prefix
117		1x	sa.sin6_addr.s6_addr[10] = 0xff;
118		1x	sa.sin6_addr.s6_addr[11] = 0xff;
119		1x	auto bytes = ep.v4_address().to_bytes();
120		1x	std::memcpy(&sa.sin6_addr.s6_addr[12], bytes.data(), 4);
121		1x	return sa;
122			}
123
124			/** Convert endpoint to sockaddr_storage.
125
126			Dispatches to @ref to_sockaddr_in or @ref to_sockaddr_in6
127			based on the endpoint's address family.
128
129			@param ep The endpoint to convert.
130			@param storage Output parameter filled with the sockaddr.
131			@return The length of the filled sockaddr structure.
132			*/
133			inline socklen_t
134		3985x	to_sockaddr(endpoint const& ep, sockaddr_storage& storage) noexcept
135			{
136		3985x	std::memset(&storage, 0, sizeof(storage));
137	2/2 ✓ Branch 3 → 4 taken 3960 times. ✓ Branch 3 → 6 taken 25 times.	3985x	if (ep.is_v4())
138			{
139		3960x	auto sa = to_sockaddr_in(ep);
140		3960x	std::memcpy(&storage, &sa, sizeof(sa));
141		3960x	return sizeof(sa);
142			}
143		25x	auto sa6 = to_sockaddr_in6(ep);
144		25x	std::memcpy(&storage, &sa6, sizeof(sa6));
145		25x	return sizeof(sa6);
146			}
147
148			/** Convert endpoint to sockaddr_storage for a specific socket family.
149
150			When the socket is AF_INET6 and the endpoint is IPv4, the address
151			is converted to an IPv4-mapped IPv6 address (`::ffff:x.x.x.x`) so
152			dual-stack sockets can connect to IPv4 destinations.
153
154			@param ep The endpoint to convert.
155			@param socket_family The address family of the socket (AF_INET or
156			AF_INET6).
157			@param storage Output parameter filled with the sockaddr.
158			@return The length of the filled sockaddr structure.
159			*/
160			inline socklen_t
161		1968x	to_sockaddr(
162			endpoint const& ep, int socket_family, sockaddr_storage& storage) noexcept
163			{
164			// IPv4 endpoint on IPv6 socket: use IPv4-mapped address
165	6/6 ✓ Branch 3 → 4 taken 1960 times. ✓ Branch 3 → 6 taken 8 times. ✓ Branch 4 → 5 taken 1 time. ✓ Branch 4 → 6 taken 1959 times. ✓ Branch 7 → 8 taken 1 time. ✓ Branch 7 → 10 taken 1967 times.	1968x	if (ep.is_v4() && socket_family == AF_INET6)
166			{
167		1x	std::memset(&storage, 0, sizeof(storage));
168		1x	auto sa6 = to_v4_mapped_sockaddr_in6(ep);
169		1x	std::memcpy(&storage, &sa6, sizeof(sa6));
170		1x	return sizeof(sa6);
171			}
172		1967x	return to_sockaddr(ep, storage);
173			}
174
175			/** Create endpoint from sockaddr_storage.
176
177			Dispatches on `ss_family` to reconstruct the appropriate
178			IPv4 or IPv6 endpoint.
179
180			@param storage The sockaddr_storage with fields in network byte order.
181			@return An endpoint with address and port extracted from storage.
182			*/
183			inline endpoint
184		7781x	from_sockaddr(sockaddr_storage const& storage) noexcept
185			{
186	2/2 ✓ Branch 2 → 3 taken 7731 times. ✓ Branch 2 → 5 taken 50 times.	7781x	if (storage.ss_family == AF_INET)
187			{
188			sockaddr_in sa;
189		7731x	std::memcpy(&sa, &storage, sizeof(sa));
190		7731x	return from_sockaddr_in(sa);
191			}
192	2/2 ✓ Branch 5 → 6 taken 49 times. ✓ Branch 5 → 8 taken 1 time.	50x	if (storage.ss_family == AF_INET6)
193			{
194			sockaddr_in6 sa6;
195		49x	std::memcpy(&sa6, &storage, sizeof(sa6));
196		49x	return from_sockaddr_in6(sa6);
197			}
198		1x	return endpoint{};
199			}
200
201			/** Return the native address family for an endpoint.
202
203			@param ep The endpoint to query.
204			@return `AF_INET` for IPv4, `AF_INET6` for IPv6.
205			*/
206			inline int
207			endpoint_family(endpoint const& ep) noexcept
208			{
209			return ep.is_v6() ? AF_INET6 : AF_INET;
210			}
211
212			/** Return the address family of a socket descriptor.
213
214			@param fd The socket file descriptor.
215			@return AF_INET, AF_INET6, or AF_UNSPEC on failure.
216			*/
217			inline int
218			socket_family(
219			#if BOOST_COROSIO_POSIX
220			int fd
221			#else
222			std::uintptr_t fd
223			#endif
224			) noexcept
225			{
226			sockaddr_storage storage{};
227			socklen_t len = sizeof(storage);
228			if (getsockname(
229			#if BOOST_COROSIO_POSIX
230			fd,
231			#else
232			static_cast<SOCKET>(fd),
233			#endif
234			reinterpret_cast<sockaddr*>(&storage), &len) != 0)
235			return AF_UNSPEC;
236			return storage.ss_family;
237			}
238
239			//----------------------------------------------------------
240			// local_endpoint (AF_UNIX) conversions
241			//----------------------------------------------------------
242
243			// Platform-agnostic sockaddr_un alias. POSIX uses the real
244			// sockaddr_un from <sys/un.h>; Windows uses a private struct
245			// matching the layout (same approach as Boost.Asio).
246			#if BOOST_COROSIO_POSIX
247			using un_sa_t = sockaddr_un;
248			#else
249			struct un_sa_t
250			{
251			u_short sun_family;
252			char sun_path[108];
253			};
254			#endif
255
256			/** Convert a local_endpoint to sockaddr_storage.
257
258			@param ep The local endpoint to convert.
259			@param storage Output parameter filled with the sockaddr_un.
260			@return The length of the filled sockaddr structure.
261			*/
262			inline socklen_t
263		68x	to_sockaddr(local_endpoint const& ep, sockaddr_storage& storage) noexcept
264			{
265		68x	std::memset(&storage, 0, sizeof(storage));
266		68x	un_sa_t sa{};
267		68x	sa.sun_family = AF_UNIX;
268		68x	auto path = ep.path();
269		68x	auto copy_len = (std::min)(path.size(), sizeof(sa.sun_path));
270	1/2 ✓ Branch 5 → 6 taken 68 times. ✗ Branch 5 → 8 not taken.	68x	if (copy_len > 0)
271		68x	std::memcpy(sa.sun_path, path.data(), copy_len);
272		68x	std::memcpy(&storage, &sa, sizeof(sa));
273
274	1/2 ✗ Branch 9 → 10 not taken. ✓ Branch 9 → 11 taken 68 times.	68x	if (ep.is_abstract())
275		✗	return static_cast<socklen_t>(offsetof(un_sa_t, sun_path) + copy_len);
276		68x	return static_cast<socklen_t>(sizeof(sa));
277			}
278
279			/** Convert a local_endpoint to sockaddr_storage (family-aware overload).
280
281			The socket_family parameter is ignored for Unix sockets since
282			there is no dual-stack mapping.
283
284			@param ep The local endpoint to convert.
285			@param socket_family Ignored.
286			@param storage Output parameter filled with the sockaddr_un.
287			@return The length of the filled sockaddr structure.
288			*/
289			inline socklen_t
290			to_sockaddr(
291			local_endpoint const& ep,
292			int /socket_family/,
293			sockaddr_storage& storage) noexcept
294			{
295			return to_sockaddr(ep, storage);
296			}
297
298			/** Create a local_endpoint from sockaddr_storage.
299
300			@param storage The sockaddr_storage (must have ss_family == AF_UNIX).
301			@param len The address length returned by the kernel.
302			@return A local_endpoint with the path extracted from the
303			sockaddr_un, or an empty endpoint if the family is not AF_UNIX.
304			*/
305			inline local_endpoint
306		168x	from_sockaddr_local(sockaddr_storage const& storage, socklen_t len) noexcept
307			{
308	1/2 ✗ Branch 2 → 3 not taken. ✓ Branch 2 → 4 taken 168 times.	168x	if (storage.ss_family != AF_UNIX)
309		✗	return local_endpoint{};
310
311		168x	un_sa_t sa{};
312		168x	std::memcpy(
313		168x	&sa, &storage, (std::min)(static_cast<std::size_t>(len), sizeof(sa)));
314
315		168x	auto path_offset = offsetof(un_sa_t, sun_path);
316	1/2 ✗ Branch 5 → 6 not taken. ✓ Branch 5 → 7 taken 168 times.	168x	if (static_cast<std::size_t>(len) <= path_offset)
317		✗	return local_endpoint{};
318
319			// Clamp to the buffer: a foreign len may overstate the payload,
320			// and sun_path is the struct's last member.
321		336x	auto path_len = (std::min)(static_cast<std::size_t>(len) - path_offset,
322		168x	sizeof(sa.sun_path));
323
324			// Non-abstract paths may be null-terminated by the kernel
325	3/4 ✓ Branch 8 → 9 taken 168 times. ✗ Branch 8 → 13 not taken. ✓ Branch 9 → 10 taken 75 times. ✓ Branch 9 → 13 taken 93 times.	168x	if (path_len > 0 && sa.sun_path[0] != '\0')
326			{
327			auto* end =
328		75x	static_cast<char const*>(std::memchr(sa.sun_path, '\0', path_len));
329	1/2 ✓ Branch 11 → 12 taken 75 times. ✗ Branch 11 → 13 not taken.	75x	if (end)
330		75x	path_len = static_cast<std::size_t>(end - sa.sun_path);
331			}
332
333			// A foreign sun_path may exceed corosio's cap; the length
334			// pre-check keeps the throwing constructor unreachable.
335	2/2 ✓ Branch 13 → 14 taken 93 times. ✓ Branch 13 → 15 taken 75 times.	168x	if (path_len > local_endpoint::max_path_length)
336		93x	return local_endpoint{};
337		75x	return local_endpoint(std::string_view(sa.sun_path, path_len));
338			}
339
340			//----------------------------------------------------------
341			// Tag-dispatch helpers for templatized reactor code.
342			// Overload resolution selects the correct conversion based
343			// on the Endpoint type.
344			//----------------------------------------------------------
345
346			/** Convert sockaddr_storage to an IP endpoint (tag overload).
347
348			@param storage The sockaddr_storage with fields in network byte order.
349			@param len The address length returned by the kernel.
350			@return An endpoint with address and port extracted from storage.
351			*/
352			inline endpoint
353			from_sockaddr_as(
354			sockaddr_storage const& storage,
355			socklen_t /len/,
356			endpoint const&) noexcept
357			{
358			return from_sockaddr(storage);
359			}
360
361			/** Convert sockaddr_storage to a local_endpoint (tag overload).
362
363			@param storage The sockaddr_storage.
364			@param len The address length returned by the kernel.
365			@return A local_endpoint with path extracted from storage.
366			*/
367			inline local_endpoint
368			from_sockaddr_as(
369			sockaddr_storage const& storage,
370			socklen_t len,
371			local_endpoint const&) noexcept
372			{
373			return from_sockaddr_local(storage, len);
374			}
375
376			} // namespace boost::corosio::detail
377
378			#endif
379