114 lines
3.0 KiB
C
114 lines
3.0 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <arpa/inet.h>
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#include <sys/socket.h>
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#include <sys/select.h>
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#include "common.h"
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/* 停等协议发送（带超时重传） */
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void send_with_stopwait(int sock,
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struct sockaddr_in6 *peer,
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struct packet *pkt, int pkt_len)
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{
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socklen_t len = sizeof(*peer);
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while (1) {
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sendto(sock, pkt, pkt_len, 0,
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(struct sockaddr *)peer, len);
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fd_set fds;
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FD_ZERO(&fds);
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FD_SET(sock, &fds);
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struct timeval tv;
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tv.tv_sec = TIMEOUT_SEC;
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tv.tv_usec = 0;
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int ret = select(sock + 1, &fds, NULL, NULL, &tv);
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if (ret > 0) {
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struct packet ack;
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recvfrom(sock, &ack, sizeof(ack), 0, NULL, NULL);
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if (ack.type == TYPE_ACK && ack.seq == pkt->seq) {
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return; // 正确 ACK
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}
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}
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printf("[timeout] retransmit\n");
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}
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}
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int main(int argc, char *argv[])
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{
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if (argc != 2) {
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printf("用法: %s <对方IPv6地址>\n", argv[0]);
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return 1;
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}
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int sock = socket(AF_INET6, SOCK_DGRAM, 0);
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/* 绑定本地 IPv6 端口 */
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struct sockaddr_in6 local;
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memset(&local, 0, sizeof(local));
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local.sin6_family = AF_INET6;
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local.sin6_addr = in6addr_any;
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local.sin6_port = htons(PORT);
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bind(sock, (struct sockaddr *)&local, sizeof(local));
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/* 对端地址 */
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struct sockaddr_in6 peer;
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memset(&peer, 0, sizeof(peer));
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peer.sin6_family = AF_INET6;
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peer.sin6_port = htons(PORT);
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inet_pton(AF_INET6, argv[1], &peer.sin6_addr);
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uint8_t send_seq = 0;
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uint8_t recv_seq = 0;
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struct packet pkt, rcv;
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memset(&pkt, 0, sizeof(pkt));
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memset(&rcv, 0, sizeof(rcv));
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printf("Linux UDP IPv6 Stop-Wait Chat\n");
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while (1) {
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/* 非阻塞接收 */
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fd_set fds;
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FD_ZERO(&fds);
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FD_SET(sock, &fds);
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struct timeval tv = {0, 100000};
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if (select(sock + 1, &fds, NULL, NULL, &tv) > 0) {
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recvfrom(sock, &rcv, sizeof(rcv), 0, NULL, NULL);
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rcv.payload[sizeof(rcv.payload) - 1] = '\0';
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if (rcv.type == TYPE_DATA) {
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if (rcv.seq == recv_seq) {
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printf("\npeer: %s\n", rcv.payload);
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recv_seq ^= 1;
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}
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rcv.type = TYPE_ACK;
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sendto(sock, &rcv, 2, 0,
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(struct sockaddr *)&peer, sizeof(peer));
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}
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}
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/* 发送 */
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printf(">> ");
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if (!fgets(pkt.payload, sizeof(pkt.payload), stdin))
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break;
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size_t len = strlen(pkt.payload);
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if (len > 0 && pkt.payload[len - 1] == '\n') pkt.payload[len - 1] = '\0';
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pkt.seq = send_seq;
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pkt.type = TYPE_DATA;
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int pkt_len = 2 + strlen(pkt.payload) + 1;
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send_with_stopwait(sock, &peer, &pkt, pkt_len);
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send_seq ^= 1;
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}
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close(sock);
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return 0;
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}
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