recv_v6.lc

unix网络编程卷1：套接口API的全书源码

#include    "trace.h"##  1 ##src/traceroute/recv_v6.c##

/*##  2 ##src/traceroute/recv_v6.c##
 * Return: -3 on timeout##  3 ##src/traceroute/recv_v6.c##
 *         -2 on ICMP time exceeded in transit (caller keeps going)##  4 ##src/traceroute/recv_v6.c##
 *         -1 on ICMP port unreachable (caller is done)##  5 ##src/traceroute/recv_v6.c##
 *       >= 0 return value is some other ICMP unreachable code##  6 ##src/traceroute/recv_v6.c##
 */##  7 ##src/traceroute/recv_v6.c##

int##  8 ##src/traceroute/recv_v6.c##
recv_v6(int seq, struct timeval *tv)##  9 ##src/traceroute/recv_v6.c##
{## 10 ##src/traceroute/recv_v6.c##
#ifdef  IPV6## 11 ##src/traceroute/recv_v6.c##
    int     hlen1, hlen2, icmp6len;## 12 ##src/traceroute/recv_v6.c##
    ssize_t n;## 13 ##src/traceroute/recv_v6.c##
    socklen_t len;## 14 ##src/traceroute/recv_v6.c##
    struct ip6_hdr *ip6, *hip6;## 15 ##src/traceroute/recv_v6.c##
    struct icmp6_hdr *icmp6;## 16 ##src/traceroute/recv_v6.c##
    struct udphdr *udp;## 17 ##src/traceroute/recv_v6.c##

    alarm(3);## 18 ##src/traceroute/recv_v6.c##
    for (;;) {## 19 ##src/traceroute/recv_v6.c##
        len = pr->salen;## 20 ##src/traceroute/recv_v6.c##
        n = recvfrom(recvfd, recvbuf, sizeof(recvbuf), 0, pr->sarecv, &len);## 21 ##src/traceroute/recv_v6.c##
        if (n < 0) {## 22 ##src/traceroute/recv_v6.c##
            if (errno == EINTR)## 23 ##src/traceroute/recv_v6.c##
                return (-3);    /* alarm expired */## 24 ##src/traceroute/recv_v6.c##
            else## 25 ##src/traceroute/recv_v6.c##
                err_sys("recvfrom error");## 26 ##src/traceroute/recv_v6.c##
        }## 27 ##src/traceroute/recv_v6.c##
        Gettimeofday(tv, NULL); /* get time of packet arrival */## 28 ##src/traceroute/recv_v6.c##

        ip6 = (struct ip6_hdr *) recvbuf;   /* start of IPv6 header */## 29 ##src/traceroute/recv_v6.c##
        hlen1 = sizeof(struct ip6_hdr);## 30 ##src/traceroute/recv_v6.c##

        icmp6 = (struct icmp6_hdr *) (recvbuf + hlen1); /* ICMP hdr */## 31 ##src/traceroute/recv_v6.c##
        if ((icmp6len = n - hlen1) < 8)## 32 ##src/traceroute/recv_v6.c##
            err_quit("icmp6len (%d) < 8", icmp6len);## 33 ##src/traceroute/recv_v6.c##

        if (icmp6->icmp6_type == ICMP6_TIME_EXCEEDED &&## 34 ##src/traceroute/recv_v6.c##
            icmp6->icmp6_code == ICMP6_TIME_EXCEED_TRANSIT) {## 35 ##src/traceroute/recv_v6.c##
            if (icmp6len < 8 + 40 + 8)## 36 ##src/traceroute/recv_v6.c##
                err_quit("icmp6len (%d) < 8 + 40 + 8", icmp6len);## 37 ##src/traceroute/recv_v6.c##

            hip6 = (struct ip6_hdr *) (recvbuf + hlen1 + 8);## 38 ##src/traceroute/recv_v6.c##
            hlen2 = sizeof(struct ip6_hdr);## 39 ##src/traceroute/recv_v6.c##
            udp = (struct udphdr *) (recvbuf + hlen1 + 8 + hlen2);## 40 ##src/traceroute/recv_v6.c##
            if (hip6->ip6_nxt == IPPROTO_UDP &&## 41 ##src/traceroute/recv_v6.c##
                udp->uh_sport == htons(sport) &&## 42 ##src/traceroute/recv_v6.c##
                udp->uh_dport == htons(dport + seq))## 43 ##src/traceroute/recv_v6.c##
                return (-2);    /* we hit an intermediate router */## 44 ##src/traceroute/recv_v6.c##

        } else if (icmp6->icmp6_type == ICMP6_DST_UNREACH) {## 45 ##src/traceroute/recv_v6.c##
            if (icmp6len < 8 + 40 + 8)## 46 ##src/traceroute/recv_v6.c##
                err_quit("icmp6len (%d) < 8 + 40 + 8", icmp6len);## 47 ##src/traceroute/recv_v6.c##

            hip6 = (struct ip6_hdr *) (recvbuf + hlen1 + 8);## 48 ##src/traceroute/recv_v6.c##
            hlen2 = 40;## 49 ##src/traceroute/recv_v6.c##
            udp = (struct udphdr *) (recvbuf + hlen1 + 8 + hlen2);## 50 ##src/traceroute/recv_v6.c##
            if (hip6->ip6_nxt == IPPROTO_UDP &&## 51 ##src/traceroute/recv_v6.c##
                udp->uh_sport == htons(sport) &&## 52 ##src/traceroute/recv_v6.c##
                udp->uh_dport == htons(dport + seq)) {## 53 ##src/traceroute/recv_v6.c##
                if (icmp6->icmp6_code == ICMP6_DST_UNREACH_NOPORT)## 54 ##src/traceroute/recv_v6.c##
                    return (-1);    /* have reached destination */## 55 ##src/traceroute/recv_v6.c##
                else## 56 ##src/traceroute/recv_v6.c##
                    return (icmp6->icmp6_code); /* 0, 1, 2, ... */## 57 ##src/traceroute/recv_v6.c##
            }## 58 ##src/traceroute/recv_v6.c##
        } else if (verbose) {## 59 ##src/traceroute/recv_v6.c##
            printf(" (from %s: type = %d, code = %d)\n",## 60 ##src/traceroute/recv_v6.c##
                   Sock_ntop_host(pr->sarecv, pr->salen),## 61 ##src/traceroute/recv_v6.c##
                   icmp6->icmp6_type, icmp6->icmp6_code);## 62 ##src/traceroute/recv_v6.c##
        }## 63 ##src/traceroute/recv_v6.c##
        /* Some other ICMP error, recvfrom() again */## 64 ##src/traceroute/recv_v6.c##
    }## 65 ##src/traceroute/recv_v6.c##
#endif## 66 ##src/traceroute/recv_v6.c##
}## 67 ##src/traceroute/recv_v6.c##