dns_rr_to_sa.c

[詳解]

/*++
/* NAME
/*  dns_rr_to_sa 3
/* SUMMARY
/*  resource record to socket address
/* SYNOPSIS
/*  #include <dns.h>
/*
/*  int dns_rr_to_sa(rr, port, sa, sa_length)
/*  DNS_RR  *rr;
/*  unsigned port;
/*  struct sockaddr *sa;
/*  SOCKADDR_SIZE *sa_length;
/* DESCRIPTION
/*  dns_rr_to_sa() converts the address in a DNS resource record into
/*  a socket address of the corresponding type.
/*
/*  Arguments:
/* .IP rr
/*  DNS resource record pointer.
/* .IP port
/*  TCP or UDP port, network byte order.
/* .IP sa
/*  Socket address pointer.
/* .IP sa_length
/*  On input, the available socket address storage space.
/*  On output, the amount of space actually used.
/* DIAGNOSTICS
/*  The result is non-zero in case of problems, with the
/*  error type returned via the errno variable.
/* 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_rr_to_sa - resource record to socket address */

int     dns_rr_to_sa(DNS_RR *rr, unsigned port, struct sockaddr *sa,
                     SOCKADDR_SIZE *sa_length)
{
    SOCKADDR_SIZE sock_addr_len;

    if (rr->type == T_A) {
    if (rr->data_len != sizeof(SOCK_ADDR_IN_ADDR(sa))) {
        errno = EINVAL;
        return (-1);
    } else if ((sock_addr_len = sizeof(*SOCK_ADDR_IN_PTR(sa))) > *sa_length) {
        errno = ENOSPC;
        return (-1);
    } else {
        memset((void *) SOCK_ADDR_IN_PTR(sa), 0, sock_addr_len);
        SOCK_ADDR_IN_FAMILY(sa) = AF_INET;
        SOCK_ADDR_IN_PORT(sa) = port;
        SOCK_ADDR_IN_ADDR(sa) = IN_ADDR(rr->data);
#ifdef HAS_SA_LEN
        sa->sa_len = sock_addr_len;
#endif
        *sa_length = sock_addr_len;
        return (0);
    }
#ifdef HAS_IPV6
    } else if (rr->type == T_AAAA) {
    if (rr->data_len != sizeof(SOCK_ADDR_IN6_ADDR(sa))) {
        errno = EINVAL;
        return (-1);
    } else if ((sock_addr_len = sizeof(*SOCK_ADDR_IN6_PTR(sa))) > *sa_length) {
        errno = ENOSPC;
        return (-1);
    } else {
        memset((void *) SOCK_ADDR_IN6_PTR(sa), 0, sock_addr_len);
        SOCK_ADDR_IN6_FAMILY(sa) = AF_INET6;
        SOCK_ADDR_IN6_PORT(sa) = port;
        SOCK_ADDR_IN6_ADDR(sa) = IN6_ADDR(rr->data);
#ifdef HAS_SA_LEN
        sa->sa_len = sock_addr_len;
#endif
        *sa_length = sock_addr_len;
        return (0);
    }
#endif
    } else {
    errno = EAFNOSUPPORT;
    return (-1);
    }
}

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

#include <stringops.h>
#include <vstream.h>
#include <myaddrinfo.h>

static const char *myname;

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

int     main(int argc, char **argv)
{
    DNS_RR *rr;
    MAI_HOSTADDR_STR hostaddr;
    MAI_SERVPORT_STR portnum;
    struct sockaddr_storage ss;
    struct sockaddr *sa = (struct sockaddr *) &ss;
    SOCKADDR_SIZE sa_length = sizeof(ss);
    VSTRING *why;
    int     type;
    int     port;

    myname = argv[0];
    if (argc < 4)
    usage();
    why = vstring_alloc(1);

    while (*++argv) {
    if (argv[1] == 0 || argv[2] == 0)
        usage();
    if ((type = dns_type(argv[0])) == 0)
        usage();
    if (!alldig(argv[2]) || (port = atoi(argv[2])) > 65535)
        usage();
    if (dns_lookup(argv[1], type, 0, &rr, (VSTRING *) 0, why) != DNS_OK)
        msg_fatal("%s: %s", argv[1], vstring_str(why));
    sa_length = sizeof(ss);
    if (dns_rr_to_sa(rr, htons(port), sa, &sa_length) != 0)
        msg_fatal("dns_rr_to_sa: %m");
    SOCKADDR_TO_HOSTADDR(sa, sa_length, &hostaddr, &portnum, 0);
    vstream_printf("%s %s -> %s %s\n",
               argv[1], argv[2], hostaddr.buf, portnum.buf);
    vstream_fflush(VSTREAM_OUT);
    argv += 2;
    dns_rr_free(rr);
    }
    vstring_free(why);
    return (0);
}

#endif