修正 checksum 計算錯誤以及重傳時可能形成無窮迴圈的問題

2 files changed, 26 insertions, 15 deletions

diff --git a/hw2/ump-pkt.c b/hw2/ump-pkt.c
index babcf34..73a66e5 100644
--- a/hw2/ump-pkt.c
+++ b/hw2/ump-pkt.c
@@ -15,7 +15,7 @@ uint16_t ump_pkt_calc_checksum (UmpPkt* pkt, bool skip_checksum) {
 	for (int i = 0; i < pkt_len / 2; i++) {
 		if ((i != 16 / 2) || !skip_checksum) {
 			uint16_t checksum_new =	checksum + pkt_data[i];
-			if (checksum_new > checksum) {
+			if (checksum_new >= checksum) {
 				checksum = checksum_new;
 			} else {
 				checksum = checksum_new + 1;
diff --git a/hw2/ump-sched.c b/hw2/ump-sched.c
index 692ad6e..7ee4e0c 100644
--- a/hw2/ump-sched.c
+++ b/hw2/ump-sched.c
@@ -111,11 +111,15 @@ static bool check_packet (UmpPkt* pkt, UmpSched* sched, size_t pkt_len) {
 	return true;
 }
 
+static int get_net_score (UmpSched* sched, int j) {
+	return sched->conn[j].score - sched->conn[j].sent;
+}
+
 static int find_high_score (UmpSched* sched) {
 	int selected = 0;
 	int net_score = INT_MIN;
 	for (int j = 0; j < sched->conn_count; j++) {
-		int net_score_this = sched->conn[j].score - sched->conn[j].sent;
+		int net_score_this = get_net_score (sched, j);
 		if (net_score_this > net_score) {
 			net_score = net_score_this;
 			selected = j;
@@ -431,8 +435,9 @@ ssize_t ump_sched_send (UmpSched* sched, void* buf, size_t count) {
 		for (int i = 0; i < sched->pkt_count;) {
 			for (int j = 0; j < sched->conn_count; j++) {
 				lbs_logger_format (sched->log,
-					"agent[%d]: # sent %d # score %d #",
-					j, sched->conn[j].sent, sched->conn[j].score);
+					"agent[%d]: # sent %d # score %d # net_score %d",
+					j, sched->conn[j].sent, sched->conn[j].score,
+					get_net_score (sched, j));
 			}
 
 			xalarm (0, 500000);
@@ -449,16 +454,20 @@ ssize_t ump_sched_send (UmpSched* sched, void* buf, size_t count) {
 					sched->conn[sched->pkt_map[i]].score--;
 
 					int selected = find_high_score (sched);
-					UmpPkt* pkt = &(sched->pkt[i]);
-					lbs_logger_format (sched->log, "REsend %s packet #%" PRIu32
-						" (agent[%d])",
-						ump_pkt_show_message (pkt), ump_pkt_get_seq_num (pkt),
-						selected);
-					sendto (sched->conn_fd, pkt,
-						ump_pkt_get_data_offset (pkt) + pkt->app_data_len, 0,
-						SOCKADDR (&(sched->conn[selected].addr)),
-						sched->conn[selected].addr_len);
-					sched->pkt_map[i] = selected;
+
+					for (int k = i; k < sched->pkt_count; k++) {
+						UmpPkt* pkt = &(sched->pkt[k]);
+						lbs_logger_format (sched->log, "REsend %s packet #%" PRIu32
+							" (agent[%d])",
+							ump_pkt_show_message (pkt), ump_pkt_get_seq_num (pkt),
+							selected);
+						sendto (sched->conn_fd, pkt,
+							ump_pkt_get_data_offset (pkt) + pkt->app_data_len, 0,
+							SOCKADDR (&(sched->conn[selected].addr)),
+							sched->conn[selected].addr_len);
+						sched->conn[selected].sent++;
+						sched->pkt_map[k] = selected;
+					}
 				}
 				continue;
 			}
@@ -474,7 +483,9 @@ ssize_t ump_sched_send (UmpSched* sched, void* buf, size_t count) {
 			}
 			uint32_t seq_rel = ump_pkt_get_seq_num (pkt_new) - sched->seq_start;
 			if (seq_rel >= 0 && seq_rel < sched->pkt_count) {
-				if (seq_rel == i) {
+				if (seq_rel > i) {
+					i = seq_rel;
+				} else if (seq_rel == i) {
 					i++;
 				}
 			}