/* SPDX-License-Identifier: GPL-2.0 */
#include <stdlib.h>
#include <errno.h>
#include <stdint.h>
#include <limits.h>
#include <arpa/inet.h>
#include <string.h>
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <inttypes.h>

#include "minecproxy.h"
#include "misc.h"
#include "uring.h"

static unsigned total_malloc_count = 0;
static int malloc_count = 0;

LIST_HEAD(malloc_list);

struct allocation {
	const char *allocfn;
	const char *callerfn;
	int line;
	void *ptr;
	size_t size;
	struct list_head list;
};

static void add_allocation(const char *allocfn, const char *callerfn, int line,
			   void *ptr, size_t size)
{
	struct allocation *a;

	assert_die(!empty_str(allocfn) && !empty_str(callerfn) && line > 0 &&
			   ptr && size > 0,
		   "invalid arguments");

	a = malloc(sizeof(*a));
	if (!a)
		die("malloc: %m");
	a->allocfn = allocfn;
	a->callerfn = callerfn;
	a->line = line;
	a->ptr = ptr;
	a->size = size;
	list_add(&a->list, &malloc_list);
	total_malloc_count++;
	malloc_count++;
	debug(DBG_MALLOC, "called from %s:%i - %s(%zu) = %p (%p)", callerfn,
	      line, allocfn, size, ptr, a);
}

void *__zmalloc(const char *fn, int line, size_t size)
{
	void *ptr;

	assert_die(!empty_str(fn) && line > 0 && size > 0, "invalid arguments");

	ptr = calloc(1, size);
	if (ptr)
		add_allocation("zmalloc", fn, line, ptr, size);
	return ptr;
}

char *__xstrdup(const char *fn, int line, const char *s)
{
	char *ptr;

	assert_die(!empty_str(fn) && line > 0 && !empty_str(s),
		   "invalid arguments");

	ptr = strdup(s);
	if (ptr)
		add_allocation("xstrdup", fn, line, ptr, strlen(s) + 1);
	return ptr;
}

char *__xstrndup(const char *fn, int line, const char *s, size_t n)
{
	char *ptr;

	assert_die(!empty_str(fn) && line > 0 && !empty_str(s) && n > 0,
		   "invalid arguments");

	ptr = strndup(s, n);
	if (ptr)
		add_allocation("xstrndup", fn, line, ptr, n);
	return ptr;
}

void __xfree(const char *fn, int line, void *ptr)
{
	struct allocation *a, *tmp;
	unsigned delete_count = 0;

	assert_die(!empty_str(fn) && line > 0, "invalid arguments");

	if (!ptr)
		return;
	debug(DBG_MALLOC, "called from %s:%i - %p", fn, line, ptr);

	list_for_each_entry_safe(a, tmp, &malloc_list, list) {
		if (a->ptr == ptr) {
			list_del(&a->list);
			free(a);
			delete_count++;
		}
	}

	if (delete_count != 1) {
		error("Delete count is %u for ptr 0x%p", delete_count, ptr);
		exit(EXIT_FAILURE);
	}

	free(ptr);
	malloc_count--;
}

void debug_resource_usage()
{
	struct allocation *a;
	DIR *dir;
	struct dirent *dent;
	char buf[4096];
	ssize_t r;
	unsigned file_count = 0;

	debug(DBG_MALLOC, "Still malloced %i (total %u)", malloc_count,
	      total_malloc_count);

	list_for_each_entry(a, &malloc_list, list) {
		debug(DBG_MALLOC,
		      "* Lost allocation - %s:%i - ptr: %p, size: %zu",
		      a->callerfn, a->line, a->ptr, a->size);
	}

	dir = opendir("/proc/self/fd");
	if (!dir) {
		error("failed to open fd dir");
		return;
	}

	debug(DBG_MALLOC, "Open files:");
	while ((dent = readdir(dir)) != NULL) {
		if (streq(dent->d_name, ".") || streq(dent->d_name, ".."))
			continue;

		r = readlinkat(dirfd(dir), dent->d_name, buf, sizeof(buf));
		if (r < 0) {
			debug(DBG_MALLOC, "Failed to readlink %s",
			      dent->d_name);
			continue;
		}
		buf[r] = '\0';
		debug(DBG_MALLOC, " * %s -> %s", dent->d_name, buf);
		file_count++;
	}
	closedir(dir);

	if (file_count > 4)
		debug(DBG_MALLOC, "Lost file descriptor(s)");

	debug(DBG_MALLOC, "CQEs used: %" PRIu64 ", SQEs used: %" PRIu64,
	      cqe_count, sqe_count);
}

void connection_set_local(struct connection *conn, int fd)
{
	assert_return(conn && fd >= 0);

	conn->local.addrlen = sizeof(conn->local.st);
	if (getsockname(fd, (struct sockaddr *)&conn->local.st,
			&conn->local.addrlen) < 0)
		sprintf(conn->local.addrstr, "<unknown>");
	else
		saddr_set_addrstr(&conn->local);
}

void connection_set_remote(struct connection *conn, struct saddr *remote)
{
	assert_return(conn && remote);

	conn->remote = *remote;
	saddr_set_addrstr(&conn->remote);
}

static void connect_next(struct uring_task *task, struct connection *conn);

static void connect_cb(struct uring_task *task, int res)
{
	struct connection *conn;

	assert_return(task && task->priv);

	conn = task->priv;
	if (res < 0) {
		debug(DBG_SRV, "%s: connection to %s failed", task->name,
		      conn->remote.addrstr);
		uring_task_close_fd(task);
		connect_next(task, conn);
		return;
	}

	connection_set_local(conn, task->fd);

	debug(DBG_SRV, "%s: connection established %s -> %s", task->name,
	      conn->local.addrstr, conn->remote.addrstr);

	conn->cb(conn, true);
}

static void connect_next(struct uring_task *task, struct connection *conn)
{
	struct saddr *remote, *tmp;
	int sfd;
	unsigned i;

	assert_return(task && conn && conn->cb);
again:
	assert_task_alive_or(DBG_UR, task, goto out);

	i = 0;
	remote = NULL;
	list_for_each_entry(tmp, conn->addrs, list) {
		if (i == conn->next_addr) {
			remote = tmp;
			break;
		}
		i++;
	}

	if (!remote) {
		debug(DBG_SRV, "%s: no more remote addresses to attempt",
		      task->name);
		goto out;
	}

	conn->next_addr++;
	connection_set_remote(conn, remote);
	debug(DBG_SRV, "%s: attempting to connect to %s", task->name,
	      conn->remote.addrstr);

	sfd = socket(conn->remote.st.ss_family, SOCK_STREAM | SOCK_CLOEXEC, 0);
	if (sfd < 0) {
		debug(DBG_SRV, "socket: %m");
		goto again;
	}

	socket_set_low_latency(sfd, cfg->socket_keepalive, cfg->socket_iptos,
			       cfg->socket_nodelay);

	task->priv = conn;
	uring_task_set_fd(task, sfd);
	uring_connect(task, &conn->remote, connect_cb);
	return;

out:
	conn->cb(conn, false);
}

void connect_any(struct uring_task *task, struct list_head *addrs,
		 struct connection *conn, connection_cb_t cb)
{
	assert_return(task && addrs && conn && cb);

	conn->next_addr = 0;
	conn->addrs = addrs;
	conn->cb = cb;
	connect_next(task, conn);
}