dns_sa_to_rr.c

[詳解]

/*++
/* NAME
/*  dns_sa_to_rr 3
/* SUMMARY
/*  socket address to resource record
/* SYNOPSIS
/*  #include <dns.h>
/*
/*  DNS_RR  *dns_sa_to_rr(hostname, pref, sa)
/*  const char *hostname;
/*  unsigned pref;
/*  struct sockaddr *sa;
/* DESCRIPTION
/*  dns_sa_to_rr() converts a socket address into a DNS resource record.
/*
/*  Arguments:
/* .IP hostname
/*  The resource record host name. This will be both the qname
/*  and the rname in the synthetic DNS resource record.
/* .IP pref
/*  The resource record MX host preference, if applicable.
/* .IP sa
/*  Binary address.
/* DIAGNOSTICS
/*  The result is a null pointer in case of problems, with the
/*  errno variable set to indicate the problem type.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System libraries. */

#include <sys_defs.h>
#include <errno.h>

/* Utility library. */

#include <msg.h>

/* DNS library. */

#include <dns.h>

/* dns_sa_to_rr - socket address to resource record */

DNS_RR *dns_sa_to_rr(const char *hostname, unsigned pref, struct sockaddr *sa)
{
#define DUMMY_TTL   0

    if (sa->sa_family == AF_INET) {
    return (dns_rr_create(hostname, hostname, T_A, C_IN, DUMMY_TTL, pref,
                  (char *) &SOCK_ADDR_IN_ADDR(sa),
                  sizeof(SOCK_ADDR_IN_ADDR(sa))));
#ifdef HAS_IPV6
    } else if (sa->sa_family == AF_INET6) {
    return (dns_rr_create(hostname, hostname, T_AAAA, C_IN, DUMMY_TTL, pref,
                  (char *) &SOCK_ADDR_IN6_ADDR(sa),
                  sizeof(SOCK_ADDR_IN6_ADDR(sa))));
#endif
    } else {
    errno = EAFNOSUPPORT;
    return (0);
    }
}

 /*
  * Stand-alone test program.
  */
#ifdef TEST
#include <stdlib.h>
#include <vstream.h>
#include <myaddrinfo.h>
#include <inet_proto.h>
#include <mymalloc.h>

static const char *myname;

static NORETURN usage(void)
{
    msg_fatal("usage: %s hostname", myname);
}

static int compare_family(const void *a, const void *b)
{
    struct addrinfo *resa = *(struct addrinfo **) a;
    struct addrinfo *resb = *(struct addrinfo **) b;

    return (resa->ai_family - resb->ai_family);
}

int     main(int argc, char **argv)
{
    MAI_HOSTADDR_STR hostaddr;
    struct addrinfo *res0;
    struct addrinfo *res;
    struct addrinfo **resv;
    size_t  len, n;
    DNS_RR *rr;
    int     aierr;

    myname = argv[0];
    if (argc < 2)
    usage();

    inet_proto_init(argv[0], INET_PROTO_NAME_ALL);

    while (*++argv) {
    if ((aierr = hostname_to_sockaddr(argv[0], (char *) 0, 0, &res0)) != 0)
        msg_fatal("%s: %s", argv[0], MAI_STRERROR(aierr));
    for (len = 0, res = res0; res != 0; res = res->ai_next)
        len += 1;
    resv = (struct addrinfo **) mymalloc(len * sizeof(*resv));
    for (len = 0, res = res0; res != 0; res = res->ai_next)
        resv[len++] = res;
    qsort((void *) resv, len, sizeof(*resv), compare_family);
    for (n = 0; n < len; n++) {
        if ((rr = dns_sa_to_rr(argv[0], 0, resv[n]->ai_addr)) == 0)
        msg_fatal("dns_sa_to_rr: %m");
        if (dns_rr_to_pa(rr, &hostaddr) == 0)
        msg_fatal("dns_rr_to_pa: %m");
        vstream_printf("%s -> %s\n", argv[0], hostaddr.buf);
        vstream_fflush(VSTREAM_OUT);
        dns_rr_free(rr);
    }
    freeaddrinfo(res0);
    myfree((void *) resv);
    }
    return (0);
}

#endif