// SPDX-License-Identifier: ISC

#include <libbasis/deadline.h>
#include <libbasis/gai_helper.h>
#include <libbasis/misc.h>

#include <trace.h>

#include <errno.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>

static int sockflag(int sockflag, bool nonblock, bool cloexec)
{
	if (nonblock)
		sockflag |= SOCK_NONBLOCK;
	if (cloexec)
		sockflag |= SOCK_CLOEXEC;
	return sockflag;
}

int gai_connect(const struct addrinfo **addr, const struct addrinfo *addrs,
		bool nonblock, bool cloexec, const struct dl *dl)
{
	struct pollfd *pfds;
	const struct addrinfo *it;
	size_t i, addrs_total = 0, addrs_done = 0;
	int errsv = 0, ret = -1;

	trace_msg(GAI, "%s(%s, %s, %d, %d, %s)\n",
		  __func__,
		  addr ? "addr" : "NULL",
		  addrs ? "addrs" : "NULL",
		  nonblock, cloexec,
		  dl ? "dl" : "NULL");

	for (it = addrs; it; it = it->ai_next)
		addrs_total++;

	trace_msg(GAI, "%s: connecting to one of %zu addresses\n", __func__,
		  addrs_total);

	pfds = calloc(addrs_total, sizeof(*pfds));
	if (!pfds)
		return -1;

	for (i = 0; i < addrs_total; ++i)
		pfds[i].fd = -1;

	/* try to connect to all results, save the fd in pfds */
	for (i = 0, it = addrs; it; i++, it = it->ai_next) {
		struct pollfd *pfd = &pfds[i];
		int fd;

		fd = socket(it->ai_family,
			    sockflag(it->ai_socktype, true, cloexec),
			    0);
		if (fd < 0) {
			errsv = errno;
			continue;
		}

		ret = connect(fd, it->ai_addr, it->ai_addrlen);
		if (!ret) {
			trace_msg(GAI, "connected to %d: early success\n", fd);

			ret = fd;
			if (addr)
				*addr = it;
			goto exit_success;
		}

		if (errno == EINPROGRESS) {
			pfd->fd = fd;
			pfd->events = POLLOUT;
			trace_msg(GAI, "adding %d to the waiting list\n", fd);
		} else {
			errsv = errno;
			close(fd);
			trace_msg(GAI, "skipping %d: early error: %d\n", fd, errsv);
		}
	}

	/* wait for the first connection to succeed or for all to fail
	 * (addrs_done == addrs_len)
	 */
	while (ret < 0 && addrs_done < addrs_total) {
		trace_msg(GAI, "waiting, addrs_done = %zu, addrs_total = %zu, ret = %d\n",
			  addrs_done, addrs_total, ret);

		if (poll_dl(pfds, addrs_total, dl) < 0) {
			errsv = errno;
			goto exit_cleanup;
		}

		for (i = 0, it = addrs; it; i++, it = it->ai_next) {
			struct pollfd *pfd = &pfds[i];
			socklen_t len;

			if (pfd->fd < 0 || !(pfd->revents & POLLOUT))
				continue;

			/* fetch a possible connection error */
			trace_msg(GAI, "reading errno for %d\n", pfd->fd);
			len = sizeof(errsv);
			if (getsockopt(pfd->fd, SOL_SOCKET, SO_ERROR,
					 &errsv, &len) < 0)
				errsv = errno;
			if (!errsv) {
				trace_msg(GAI, "connected to %d: late success\n", pfd->fd);

				ret = pfd->fd;
				if (addr)
					*addr = it;
				pfd->fd = -1;
				goto exit_success;
			}

			trace_msg(GAI, "got an error %d: %s, increasing nfds_done\n",
				  errsv, strerror(errsv));
			addrs_done++;
			close(pfd->fd);
			pfd->fd = -1;
		}
	}

exit_success:
	if (ret >= 0) {
		trace_msg(GAI, "returning %d: success\n", ret);

		/* clear nonblock first if it was not requested */
		if (!nonblock) {
			trace_msg(GAI, "clearing nonblock for %d\n", ret);
			if (fd_set_block(ret, true) < 0) {
				errsv = errno;
				close(ret);
				ret = -1;
				goto exit_cleanup;
			}
		}
	}

exit_cleanup:
	for (i = 0; i < addrs_total; ++i) {
		struct pollfd *pfd = &pfds[i];

		if (pfd->fd >= 0)
			close(pfd->fd);
	}
	free(pfds);
	errno = errsv;
	return ret;
}

int gai_bind(const struct addrinfo **addr, const struct addrinfo *addrs,
	     int sock_fd, bool nonblock, bool cloexec)
{
	int errsv = 0;
	const struct addrinfo *it;
	size_t addrs_total = 0;

	trace_msg(GAI, "%s(%s, %s, %d, %d, %d)\n",
		  __func__,
		  addr ? "addr" : "NULL",
		  addrs ? "addrs" : "NULL",
		  sock_fd,
		  nonblock,
		  cloexec);

	for (it = addrs; it; it = it->ai_next)
		addrs_total++;

	trace_msg(GAI, "%s: binding to one of %zu addresses\n", __func__,
		  addrs_total);

	/* try to bind to all results in sequence */
	for (it = addrs; it; it = it->ai_next) {
		int fd;

		if (sock_fd < 0) {
			fd = socket(it->ai_family,
				    sockflag(it->ai_socktype, nonblock,
					     cloexec),
				    0);
			if (fd < 0) {
				errsv = errno;
				continue;
			}
		} else {
			fd = sock_fd;
		}

		if (bind(fd, it->ai_addr, it->ai_addrlen) < 0) {
			errsv = errno;
			if (sock_fd < 0)
				close(fd);
			continue;
		}

		if (addr)
			*addr = it;
		return fd;
	}

	errno = errsv;
	return -1;
}