connect.c

/*
 * Copyright 2023-2024 Gaël PORTAY
 *
 * SPDX-License-Identifier: LGPL-2.1-or-later
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <dlfcn.h>

#include <sys/un.h>
#include <sys/socket.h>

#include "iamroot.h"

static int (*sym)(int, const struct sockaddr *, socklen_t);

hidden int next_connect(int socket, const struct sockaddr *addr,
			socklen_t addrlen)
{
	if (!sym)
		sym = dlsym(RTLD_NEXT, "connect");

	if (!sym)
		return __dl_set_errno_and_perror(ENOSYS, -1);

	return sym(socket, addr, addrlen);
}

int connect(int socket, const struct sockaddr *addr, socklen_t addrlen)
{
	struct sockaddr_un buf = { .sun_family = AF_UNIX, .sun_path = { 0 }};
	struct sockaddr_un *addrun = (struct sockaddr_un *)addr;
	socklen_t buflen = SUN_LEN(&buf);
	int ret = -1;
	ssize_t siz;

	/* Do not proceed to any hack if not an Unix socket */
	if (!addrun || addrun->sun_family != AF_UNIX || !*addrun->sun_path)
		return next_connect(socket, addr, addrlen);

	siz = path_resolution(AT_FDCWD, addrun->sun_path, buf.sun_path,
			      sizeof(buf.sun_path), 0);
	if (siz == -1 && errno == ENAMETOOLONG) {
		char *path;

		path = _getenv("IAMROOT_PATH_RESOLUTION_AF_UNIX");
		if (path) {
			int n = _snprintf(buf.sun_path, sizeof(buf.sun_path),
				  "%s/%s", path, __basename(addrun->sun_path));
			if (n == -1)
				goto exit;

			siz = n;
		}
	}
	if (siz == -1)
		goto exit;

	buflen = SUN_LEN(&buf);

	ret = next_connect(socket, (const struct sockaddr *)&buf, buflen);

exit:
	__debug("%s(socket: %i, addr: { .sun_path: '%s' -> '%s', ... }, addrlen: %i -> %i) -> %i\n",
		__func__, socket, addrun->sun_path, buf.sun_path,
		addrlen, buflen, ret);

	return ret;
}