/*
	 * Copyright (C) 2010-2025 Red Hat, Inc.  All rights reserved.
	 *
	 * Authors: Fabio M. Di Nitto <fabbione@kronosnet.org>
	 *          Federico Simoncelli <fsimon@kronosnet.org>
	 *
	 * This software licensed under LGPL-2.0+
	 */
	
	#include "config.h"
	
	#include <stdlib.h>
	#include <string.h>
	#include <errno.h>
	#include <pthread.h>
	#include <stdio.h>
	
	#include "host.h"
	#include "internals.h"
	#include "logging.h"
	#include "threads_common.h"
	
	static void _host_list_update(knet_handle_t knet_h)
	{
		struct knet_host *host;
		knet_h->host_ids_entries = 0;
	

		for (host = knet_h->host_head; host != NULL; host = host->next) {
			knet_h->host_ids[knet_h->host_ids_entries] = host->host_id;
			knet_h->host_ids_entries++;
		}
	}
	
	int knet_host_add(knet_handle_t knet_h, knet_node_id_t host_id)
	{
		int savederrno = 0, err = 0;
		struct knet_host *host = NULL;
		uint8_t link_idx;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		savederrno = get_global_wrlock(knet_h);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get write lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		if (knet_h->host_index[host_id]) {
			err = -1;
			savederrno = EEXIST;
			log_err(knet_h, KNET_SUB_HOST, "Unable to add host %u: %s",
				  host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		host = malloc(sizeof(struct knet_host));
		if (!host) {
			err = -1;
			savederrno = errno;
			log_err(knet_h, KNET_SUB_HOST, "Unable to allocate memory for host %u: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		memset(host, 0, sizeof(struct knet_host));
	
		/*
		 * set host_id
		 */
		host->host_id = host_id;
	
		/*
		 * set default host->name to host_id for logging
		 */
		snprintf(host->name, KNET_MAX_HOST_LEN, "%u", host_id);
	
		/*
		 * initialize links internal data
		 */
		for (link_idx = 0; link_idx < KNET_MAX_LINK; link_idx++) {
			host->link[link_idx].link_id = link_idx;
			host->link[link_idx].status.stats.latency_min = UINT32_MAX;
		}
	
		/*
		 * add new host to the index
		 */
		knet_h->host_index[host_id] = host;
	
		/*
		 * add new host to host list
		 */
		if (knet_h->host_head) {
			host->next = knet_h->host_head;
		}
		knet_h->host_head = host;
	
		_host_list_update(knet_h);
	
	exit_unlock:
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		if (err < 0) {
			free(host);
		}
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_remove(knet_handle_t knet_h, knet_node_id_t host_id)
	{
		int savederrno = 0, err = 0;
		struct knet_host *host, *removed;
		uint8_t link_idx;
	

		if (!_is_valid_handle(knet_h)) {
			return -1;

		}
	
		savederrno = get_global_wrlock(knet_h);

		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get write lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;

		}
	
		host = knet_h->host_index[host_id];
	

		if (!host) {
			err = -1;
			savederrno = EINVAL;
			log_err(knet_h, KNET_SUB_HOST, "Unable to remove host %u: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;

		}
	
		/*
		 * if links are configured we cannot release the host
		 */
	

		for (link_idx = 0; link_idx < KNET_MAX_LINK; link_idx++) {

			if (host->link[link_idx].configured) {
				err = -1;
				savederrno = EBUSY;
				log_err(knet_h, KNET_SUB_HOST, "Unable to remove host %u, links are still configured: %s",
					host_id, strerror(savederrno));
				goto exit_unlock;

			}

		}
	
		removed = NULL;
	
		/*
		 * removing host from list
		 */

		if (knet_h->host_head->host_id == host_id) {
			removed = knet_h->host_head;
			knet_h->host_head = removed->next;
		} else {
			for (host = knet_h->host_head; host->next != NULL; host = host->next) {
				if (host->next->host_id == host_id) {
					removed = host->next;
					host->next = removed->next;
					break;
				}
			}
		}
	
		knet_h->host_index[host_id] = NULL;
		free(removed);
	
		_host_list_update(knet_h);
	
	exit_unlock:
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_set_name(knet_handle_t knet_h, knet_node_id_t host_id, const char *name)
	{
		int savederrno = 0, err = 0;
		struct knet_host *host;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		savederrno = get_global_wrlock(knet_h);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get write lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		if (!knet_h->host_index[host_id]) {
			err = -1;
			savederrno = EINVAL;
			log_err(knet_h, KNET_SUB_HOST, "Unable to find host %u to set name: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		if (!name) {
			err = -1;
			savederrno = EINVAL;
			log_err(knet_h, KNET_SUB_HOST, "Unable to set name for host %u: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		if (strlen(name) >= KNET_MAX_HOST_LEN) {
			err = -1;
			savederrno = EINVAL;
			log_err(knet_h, KNET_SUB_HOST, "Requested name for host %u is too long: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		for (host = knet_h->host_head; host != NULL; host = host->next) {
			if (!strncmp(host->name, name, KNET_MAX_HOST_LEN)) {
				err = -1;
				savederrno = EEXIST;
				log_err(knet_h, KNET_SUB_HOST, "Duplicated name found on host_id %u",
					host->host_id);
				goto exit_unlock;
			}
		}
	
		snprintf(knet_h->host_index[host_id]->name, KNET_MAX_HOST_LEN, "%s", name);
	
	exit_unlock:
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_get_name_by_host_id(knet_handle_t knet_h, knet_node_id_t host_id,
					  char *name)
	{
		int savederrno = 0, err = 0;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		if (!name) {
			errno = EINVAL;
			return -1;
		}
	
		savederrno = pthread_rwlock_rdlock(&knet_h->global_rwlock);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get read lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		if (!knet_h->host_index[host_id]) {
			savederrno = EINVAL;
			err = -1;
			log_debug(knet_h, KNET_SUB_HOST, "Host %u not found", host_id);
			goto exit_unlock;
		}
	
		snprintf(name, KNET_MAX_HOST_LEN, "%s", knet_h->host_index[host_id]->name);
	
	exit_unlock:
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_get_id_by_host_name(knet_handle_t knet_h, const char *name,
					  knet_node_id_t *host_id)
	{
		int savederrno = 0, err = 0, found = 0;
		struct knet_host *host;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		if (!name) {
			errno = EINVAL;
			return -1;
		}
	
		if (!host_id) {
			errno = EINVAL;
			return -1;
		}
	
		savederrno = pthread_rwlock_rdlock(&knet_h->global_rwlock);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get read lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		for (host = knet_h->host_head; host != NULL; host = host->next) {
			if (!strncmp(name, host->name, KNET_MAX_HOST_LEN)) {
				found = 1;
				*host_id = host->host_id;
				break;
			}
		}
	
		if (!found) {
			savederrno = ENOENT;
			err = -1;
		}
	
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_get_host_list(knet_handle_t knet_h,
				    knet_node_id_t *host_ids, size_t *host_ids_entries)
	{
		int savederrno = 0;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		if ((!host_ids) || (!host_ids_entries)) {
			errno = EINVAL;
			return -1;
		}
	
		savederrno = pthread_rwlock_rdlock(&knet_h->global_rwlock);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get read lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		memmove(host_ids, knet_h->host_ids, sizeof(knet_h->host_ids));
		*host_ids_entries = knet_h->host_ids_entries;
	
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		return 0;
	}
	
	int knet_host_set_policy(knet_handle_t knet_h, knet_node_id_t host_id,
				 uint8_t policy)
	{
		int savederrno = 0, err = 0;
		uint8_t old_policy;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		if (policy > KNET_LINK_POLICY_RR) {
			errno = EINVAL;
			return -1;
		}
	
		savederrno = get_global_wrlock(knet_h);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get write lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		if (!knet_h->host_index[host_id]) {
			err = -1;
			savederrno = EINVAL;
			log_err(knet_h, KNET_SUB_HOST, "Unable to set name for host %u: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		old_policy = knet_h->host_index[host_id]->link_handler_policy;
		knet_h->host_index[host_id]->link_handler_policy = policy;
	
		if (_host_dstcache_update_async(knet_h, knet_h->host_index[host_id])) {
			savederrno = errno;
			err = -1;
			knet_h->host_index[host_id]->link_handler_policy = old_policy;
			log_debug(knet_h, KNET_SUB_HOST, "Unable to update switch cache for host %u: %s",
				  host_id, strerror(savederrno));
		}
	
		log_debug(knet_h, KNET_SUB_HOST, "Host %u has new switching policy: %u", host_id, policy);
	
	exit_unlock:
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_get_policy(knet_handle_t knet_h, knet_node_id_t host_id,
				 uint8_t *policy)
	{
		int savederrno = 0, err = 0;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		if (!policy) {
			errno = EINVAL;
			return -1;
		}
	
		savederrno = pthread_rwlock_rdlock(&knet_h->global_rwlock);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get read lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		if (!knet_h->host_index[host_id]) {
			err = -1;
			savederrno = EINVAL;
			log_err(knet_h, KNET_SUB_HOST, "Unable to get name for host %u: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		*policy = knet_h->host_index[host_id]->link_handler_policy;
	
	exit_unlock:
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_get_status(knet_handle_t knet_h, knet_node_id_t host_id,
				 struct knet_host_status *status)
	{
		int savederrno = 0, err = 0;
		struct knet_host *host;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		if (!status) {
			errno = EINVAL;
			return -1;
		}
	
		savederrno = pthread_rwlock_rdlock(&knet_h->global_rwlock);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get read lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		host = knet_h->host_index[host_id];
		if (!host) {
			err = -1;
			savederrno = EINVAL;
			log_err(knet_h, KNET_SUB_HOST, "Unable to find host %u: %s",
				host_id, strerror(savederrno));
			goto exit_unlock;
		}
	
		memmove(status, &host->status, sizeof(struct knet_host_status));
	
	exit_unlock:
		pthread_rwlock_unlock(&knet_h->global_rwlock);
		errno = err ? savederrno : 0;
		return err;
	}
	
	int knet_host_enable_status_change_notify(knet_handle_t knet_h,
						  void *host_status_change_notify_fn_private_data,
						  void (*host_status_change_notify_fn) (
							void *private_data,
							knet_node_id_t host_id,
							uint8_t reachable,
							uint8_t remote,
							uint8_t external))
	{
		int savederrno = 0;
	
		if (!_is_valid_handle(knet_h)) {
			return -1;
		}
	
		savederrno = get_global_wrlock(knet_h);
		if (savederrno) {
			log_err(knet_h, KNET_SUB_HOST, "Unable to get write lock: %s",
				strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		knet_h->host_status_change_notify_fn_private_data = host_status_change_notify_fn_private_data;
		knet_h->host_status_change_notify_fn = host_status_change_notify_fn;
		if (knet_h->host_status_change_notify_fn) {
			log_debug(knet_h, KNET_SUB_HOST, "host_status_change_notify_fn enabled");
		} else {
			log_debug(knet_h, KNET_SUB_HOST, "host_status_change_notify_fn disabled");
		}
	
		pthread_rwlock_unlock(&knet_h->global_rwlock);
	
		errno = 0;
		return 0;
	}
	
	static void _clear_cbuffers(struct knet_host *host, seq_num_t rx_seq_num)
	{
		int i;
	
		memset(host->circular_buffer, 0, KNET_CBUFFER_SIZE);
		host->rx_seq_num = rx_seq_num;
	
		memset(host->circular_buffer_defrag, 0, KNET_CBUFFER_SIZE);
	
		for (i = 0; i < KNET_DEFRAG_BUFFERS; i++) {
			memset(&host->defrag_buf[i], 0, sizeof(struct knet_host_defrag_buf));
		}
	}
	
	static void _reclaim_old_defrag_bufs(struct knet_host *host, seq_num_t seq_num)
	{
		seq_num_t head, tail; /* seq_num boundaries */
		int i;
	
		head = seq_num + 1;
		tail = seq_num - (KNET_DEFRAG_BUFFERS + 1);
	
		/*
		 * expire old defrag buffers
		 */
		for (i = 0; i < KNET_DEFRAG_BUFFERS; i++) {
			if (host->defrag_buf[i].in_use) {
				/*
				 * head has done a rollover to 0+
				 */
				if (tail > head) {
					if ((host->defrag_buf[i].pckt_seq >= head) && (host->defrag_buf[i].pckt_seq <= tail)) {
						host->defrag_buf[i].in_use = 0;
					}
				} else {
					if ((host->defrag_buf[i].pckt_seq >= head) || (host->defrag_buf[i].pckt_seq <= tail)){
						host->defrag_buf[i].in_use = 0;
					}
				}
			}
		}
	}
	
	/*
	 * check if a given packet seq num is in the circular buffers
	 * defrag_buf = 0 -> use normal cbuf 1 -> use the defrag buffer lookup
	 */
	
	int _seq_num_lookup(struct knet_host *host, seq_num_t seq_num, int defrag_buf, int clear_buf)
	{
		size_t head, tail; /* circular buffer indexes */
		seq_num_t seq_dist;
		char *dst_cbuf = host->circular_buffer;
		char *dst_cbuf_defrag = host->circular_buffer_defrag;
		seq_num_t *dst_seq_num = &host->rx_seq_num;
	
		/*
		 * There is a potential race condition where the sender
		 * is overloaded, sending data packets before pings
		 * can kick in and set the correct dst_seq_num.
		 *
		 * if this node is starting up (dst_seq_num = 0),
		 * it can start rejecing valid packets and get stuck.
		 *
		 * Set the dst_seq_num to the first seen packet and
		 * use that as reference instead.
		 */
		if (!*dst_seq_num) {
			*dst_seq_num = seq_num;
		}
	
		if (clear_buf) {
			_clear_cbuffers(host, seq_num);
		}
	
		_reclaim_old_defrag_bufs(host, *dst_seq_num);
	
		if (seq_num < *dst_seq_num) {
			seq_dist =  (SEQ_MAX - seq_num) + *dst_seq_num;
		} else {
			seq_dist = *dst_seq_num - seq_num;
		}
	
		head = seq_num % KNET_CBUFFER_SIZE;
	
		if (seq_dist < KNET_CBUFFER_SIZE) { /* seq num is in ring buffer */
			if (!defrag_buf) {
				return (dst_cbuf[head] == 0) ? 1 : 0;
			} else {
				return (dst_cbuf_defrag[head] == 0) ? 1 : 0;
			}
		} else if (seq_dist <= SEQ_MAX - KNET_CBUFFER_SIZE) {
			memset(dst_cbuf, 0, KNET_CBUFFER_SIZE);
			memset(dst_cbuf_defrag, 0, KNET_CBUFFER_SIZE);
			*dst_seq_num = seq_num;
		}
	
		/* cleaning up circular buffer */
		tail = (*dst_seq_num + 1) % KNET_CBUFFER_SIZE;
	
		if (tail > head) {
			memset(dst_cbuf + tail, 0, KNET_CBUFFER_SIZE - tail);
			memset(dst_cbuf, 0, head + 1);
			memset(dst_cbuf_defrag + tail, 0, KNET_CBUFFER_SIZE - tail);
			memset(dst_cbuf_defrag, 0, head + 1);
		} else {
			memset(dst_cbuf + tail, 0, head - tail + 1);
			memset(dst_cbuf_defrag + tail, 0, head - tail + 1);
		}
	
		*dst_seq_num = seq_num;
	
		return 1;
	}
	
	void _seq_num_set(struct knet_host *host, seq_num_t seq_num, int defrag_buf)
	{
		if (!defrag_buf) { 
			host->circular_buffer[seq_num % KNET_CBUFFER_SIZE] = 1;
		} else {
			host->circular_buffer_defrag[seq_num % KNET_CBUFFER_SIZE] = 1;
		}
	
		return;
	}
	
	int _host_dstcache_update_async(knet_handle_t knet_h, struct knet_host *host)
	{
		int savederrno = 0;
		knet_node_id_t host_id = host->host_id;
	
		if (sendto(knet_h->dstsockfd[1], &host_id, sizeof(host_id), MSG_DONTWAIT | MSG_NOSIGNAL, NULL, 0) != sizeof(host_id)) {
			savederrno = errno;
			log_debug(knet_h, KNET_SUB_HOST, "Unable to write to dstpipefd[1]: %s",
				  strerror(savederrno));
			errno = savederrno;
			return -1;
		}
	
		return 0;
	}
	
	int _host_dstcache_update_sync(knet_handle_t knet_h, struct knet_host *host)
	{
		int link_idx;
		int best_priority = -1;
		int reachable = 0;
	
		if (knet_h->host_id == host->host_id && knet_h->has_loop_link) {
			host->active_link_entries = 1;
			return 0;
		}
	
		host->active_link_entries = 0;
		for (link_idx = 0; link_idx < KNET_MAX_LINK; link_idx++) {
			if (host->link[link_idx].status.enabled != 1) /* link is not enabled */
				continue;
			if (host->link[link_idx].status.connected != 1) /* link is not enabled */
				continue;
			if (host->link[link_idx].has_valid_mtu != 1) /* link does not have valid MTU */
				continue;
	
			if (host->link_handler_policy == KNET_LINK_POLICY_PASSIVE) {
				/* for passive we look for the only active link with higher priority */
				if (host->link[link_idx].priority > best_priority) {
					host->active_links[0] = link_idx;
					best_priority = host->link[link_idx].priority;
				}
				host->active_link_entries = 1;
			} else {
				/* for RR and ACTIVE we need to copy all available links */
				host->active_links[host->active_link_entries] = link_idx;
				host->active_link_entries++;
			}
		}
	
		if (host->link_handler_policy == KNET_LINK_POLICY_PASSIVE) {
			log_info(knet_h, KNET_SUB_HOST, "host: %u (passive) best link: %u (pri: %u)",
				 host->host_id, host->link[host->active_links[0]].link_id,
				 host->link[host->active_links[0]].priority);
		} else {
			log_info(knet_h, KNET_SUB_HOST, "host: %u has %u active links",
				 host->host_id, host->active_link_entries);
		}
	
		/* no active links, we can clean the circular buffers and indexes */
		if (!host->active_link_entries) {
			log_warn(knet_h, KNET_SUB_HOST, "host: %u has no active links", host->host_id);
			_clear_cbuffers(host, 0);
		} else {
			reachable = 1;
		}
	
		if (host->status.reachable != reachable) {
			host->status.reachable = reachable;
			if (knet_h->host_status_change_notify_fn) {
				knet_h->host_status_change_notify_fn(
							     knet_h->host_status_change_notify_fn_private_data,
							     host->host_id,
							     host->status.reachable,
							     host->status.remote,
							     host->status.external);
			}
		}
	
		return 0;
	}