myaddrinfo.c

[詳解]

/*++
/* NAME
/*  myaddrinfo 3
/* SUMMARY
/*  addrinfo encapsulation and emulation
/* SYNOPSIS
/*  #include <myaddrinfo.h>
/*
/*  #define MAI_V4ADDR_BITS ...
/*  #define MAI_V6ADDR_BITS ...
/*  #define MAI_V4ADDR_BYTES ...
/*  #define MAI_V6ADDR_BYTES ...
/*
/*  typedef struct { char buf[....]; } MAI_HOSTNAME_STR;
/*  typedef struct { char buf[....]; } MAI_HOSTADDR_STR;
/*  typedef struct { char buf[....]; } MAI_SERVNAME_STR;
/*  typedef struct { char buf[....]; } MAI_SERVPORT_STR;
/*
/*  int hostname_to_sockaddr(hostname, service, socktype, result)
/*  const char *hostname;
/*  const char *service;
/*  int socktype;
/*  struct addrinfo **result;
/*
/*  int hostname_to_sockaddr_pf(hostname, pf, service, socktype, result)
/*  const char *hostname;
/*  int pf;
/*  const char *service;
/*  int socktype;
/*  struct addrinfo **result;
/*
/*  int hostaddr_to_sockaddr(hostaddr, service, socktype, result)
/*  const char *hostaddr;
/*  const char *service;
/*  int socktype;
/*  struct addrinfo **result;
/*
/*  int sockaddr_to_hostaddr(sa, salen, hostaddr, portnum, socktype)
/*  const struct sockaddr *sa;
/*  SOCKADDR_SIZE salen;
/*  MAI_HOSTADDR_STR *hostaddr;
/*  MAI_SERVPORT_STR *portnum;
/*  int socktype;
/*
/*  int sockaddr_to_hostname(sa, salen, hostname, service, socktype)
/*  const struct sockaddr *sa;
/*  SOCKADDR_SIZE salen;
/*  MAI_HOSTNAME_STR *hostname;
/*  MAI_SERVNAME_STR *service;
/*  int socktype;
/*
/*  const char *MAI_STRERROR(error)
/*  int error;
/* DESCRIPTION
/*  This module provides a simplified user interface to the
/*  getaddrinfo(3) and getnameinfo(3) routines (which provide
/*  a unified interface to manipulate IPv4 and IPv6 socket
/*  address structures).
/*
/*  On systems without getaddrinfo(3) and getnameinfo(3) support,
/*  emulation for IPv4 only can be enabled by defining
/*  EMULATE_IPV4_ADDRINFO.
/*
/*  hostname_to_sockaddr() looks up the binary addresses for
/*  the specified symbolic hostname or numeric address.  The
/*  result should be destroyed with freeaddrinfo(). A null host
/*  pointer converts to the null host address.
/*
/*  hostname_to_sockaddr_pf() is an extended interface that
/*  provides a protocol family override.
/*
/*  hostaddr_to_sockaddr() converts a printable network address
/*  into the corresponding binary form.  The result should be
/*  destroyed with freeaddrinfo(). A null host pointer converts
/*  to the null host address.
/*
/*  sockaddr_to_hostaddr() converts a binary network address
/*  into printable form. The result buffers should be large
/*  enough to hold the printable address or port including the
/*  null terminator.
/*  This function strips off the IPv6 datalink suffix.
/*
/*  sockaddr_to_hostname() converts a binary network address
/*  into a hostname or service.  The result buffer should be
/*  large enough to hold the hostname or service including the
/*  null terminator. This routine rejects malformed hostnames
/*  or numeric hostnames and pretends that the lookup failed.
/*
/*  MAI_STRERROR() is an unsafe macro (it evaluates the argument
/*  multiple times) that invokes strerror() or gai_strerror()
/*  as appropriate.
/*
/*  This module exports the following constants that should be
/*  user for storage allocation of name or address information:
/* .IP MAI_V4ADDR_BITS
/* .IP MAI_V6ADDR_BITS
/* .IP MAI_V4ADDR_BYTES
/* .IP MAI_V6ADDR_BYTES
/*  The number of bits or bytes needed to store a binary
/*  IPv4 or IPv6 network address.
/* .PP
/*  The types MAI_HOST{NAME,ADDR}_STR and MAI_SERV{NAME,PORT}_STR
/*  implement buffers for the storage of the string representations
/*  of symbolic or numerical hosts or services. Do not use
/*  buffer types other than the ones that are expected here,
/*  or things will blow up with buffer overflow problems.
/*
/*  Arguments:
/* .IP hostname
/*  On input to hostname_to_sockaddr(), a numeric or symbolic
/*  hostname, or a null pointer (meaning the wild-card listen
/*  address).  On output from sockaddr_to_hostname(), storage
/*  for the result hostname, or a null pointer.
/* .IP pf
/*  Protocol type: PF_UNSPEC (meaning: use any protocol that is
/*  available), PF_INET, or PF_INET6.  This argument is ignored
/*  in EMULATE_IPV4_ADDRINFO mode.
/* .IP hostaddr
/*  On input to hostaddr_to_sockaddr(), a numeric hostname,
/*  or a null pointer (meaning the wild-card listen address).
/*  On output from sockaddr_to_hostaddr(), storage for the
/*  result hostaddress, or a null pointer.
/* .IP service
/*  On input to hostname/addr_to_sockaddr(), a numeric or
/*  symbolic service name, or a null pointer in which case the
/*  socktype argument is ignored.  On output from
/*  sockaddr_to_hostname/addr(), storage for the result service
/*  name, or a null pointer.
/* .IP portnum
/*  Storage for the result service port number, or a null pointer.
/* .IP socktype
/*  Socket type: SOCK_STREAM, SOCK_DGRAM, etc. This argument is
/*  ignored when no service or port are specified.
/* .IP sa
/*  Protocol-independent socket address structure.
/* .IP salen
/*  Protocol-dependent socket address structure size in bytes.
/* SEE ALSO
/*  getaddrinfo(3), getnameinfo(3), freeaddrinfo(3), gai_strerror(3)
/* DIAGNOSTICS
/*  All routines either return 0 upon success, or an error code
/*  that is compatible with gai_strerror().
/*
/*  On systems where addrinfo support is emulated by Postfix,
/*  some out-of-memory errors are not reported to the caller,
/*  but are handled by mymalloc().
/* BUGS
/*  The IPv4-only emulation code does not support requests that
/*  specify a service but no socket type. It returns an error
/*  indication, instead of enumerating all the possible answers.
/*
/*  The hostname/addr_to_sockaddr() routines should accept a
/*  list of address families that the caller is interested in,
/*  and they should return only information of those types.
/*
/*  Unfortunately, it is not possible to remove unwanted address
/*  family results from hostname_to_sockaddr(), because we
/*  don't know how the system library routine getaddrinfo()
/*  allocates memory.  For example, getaddrinfo() could save
/*  space by referencing the same string object from multiple
/*  addrinfo structures; or it could allocate a string object
/*  and the addrinfo structure as one memory block.
/*
/*  We could get around this by copying getaddrinfo() results
/*  to our own private data structures, but that would only
/*  make an already expensive API even more expensive.
/*
/*  A better workaround is to return a vector of addrinfo
/*  pointers to the elements that contain only the elements
/*  that the caller is interested in. The pointer to the
/*  original getaddrinfo() result can be hidden at the end
/*  after the null terminator, or before the first element.
/* 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 library. */

#include <sys_defs.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>          /* sprintf() */

/* Utility library. */

#include <mymalloc.h>
#include <valid_hostname.h>
#include <sock_addr.h>
#include <stringops.h>
#include <msg.h>
#include <inet_proto.h>
#include <myaddrinfo.h>
#include <split_at.h>

/* Application-specific. */

 /*
  * Use an old trick to save some space: allocate space for two objects in
  * one. In Postfix we often use this trick for structures that have an array
  * of things at the end.
  */
struct ipv4addrinfo {
    struct addrinfo info;
    struct sockaddr_in sin;
};

 /*
  * When we're not interested in service ports, we must pick a socket type
  * otherwise getaddrinfo() will give us duplicate results: one set for TCP,
  * and another set for UDP. For consistency, we'll use the same default
  * socket type for the results from emulation mode.
  */
#define MAI_SOCKTYPE    SOCK_STREAM /* getaddrinfo() query */

#ifdef EMULATE_IPV4_ADDRINFO

/* clone_ipv4addrinfo - clone ipv4addrinfo structure */

static struct ipv4addrinfo *clone_ipv4addrinfo(struct ipv4addrinfo * tp)
{
    struct ipv4addrinfo *ip;

    ip = (struct ipv4addrinfo *) mymalloc(sizeof(*ip));
    *ip = *tp;
    ip->info.ai_addr = (struct sockaddr *) &(ip->sin);
    return (ip);
}

/* init_ipv4addrinfo - initialize an ipv4addrinfo structure */

static void init_ipv4addrinfo(struct ipv4addrinfo * ip, int socktype)
{

    /*
     * Portability: null pointers aren't necessarily all-zero bits, so we
     * make explicit assignments to all the pointers that we're aware of.
     */
    memset((void *) ip, 0, sizeof(*ip));
    ip->info.ai_family = PF_INET;
    ip->info.ai_socktype = socktype;
    ip->info.ai_protocol = 0;           /* XXX */
    ip->info.ai_addrlen = sizeof(ip->sin);
    ip->info.ai_canonname = 0;
    ip->info.ai_addr = (struct sockaddr *) &(ip->sin);
    ip->info.ai_next = 0;
    ip->sin.sin_family = AF_INET;
#ifdef HAS_SA_LEN
    ip->sin.sin_len = sizeof(ip->sin);
#endif
}

/* find_service - translate numeric or symbolic service name */

static int find_service(const char *service, int socktype)
{
    struct servent *sp;
    const char *proto;
    unsigned port;

    if (alldig(service)) {
    port = atoi(service);
    return (port < 65536 ? htons(port) : -1);
    }
    if (socktype == SOCK_STREAM) {
    proto = "tcp";
    } else if (socktype == SOCK_DGRAM) {
    proto = "udp";
    } else {
    return (-1);
    }
    if ((sp = getservbyname(service, proto)) != 0) {
    return (sp->s_port);
    } else {
    return (-1);
    }
}

#endif

/* hostname_to_sockaddr_pf - hostname to binary address form */

int     hostname_to_sockaddr_pf(const char *hostname, int pf,
                        const char *service, int socktype,
                        struct addrinfo ** res)
{
#ifdef EMULATE_IPV4_ADDRINFO

    /*
     * Emulated getaddrinfo(3) version.
     */
    static struct ipv4addrinfo template;
    struct ipv4addrinfo *ip;
    struct ipv4addrinfo *prev;
    struct in_addr addr;
    struct hostent *hp;
    char  **name_list;
    int     port;

    /*
     * Validate the service.
     */
    if (service) {
    if ((port = find_service(service, socktype)) < 0)
        return (EAI_SERVICE);
    } else {
    port = 0;
    socktype = MAI_SOCKTYPE;
    }

    /*
     * No host means INADDR_ANY.
     */
    if (hostname == 0) {
    ip = (struct ipv4addrinfo *) mymalloc(sizeof(*ip));
    init_ipv4addrinfo(ip, socktype);
    ip->sin.sin_addr.s_addr = INADDR_ANY;
    ip->sin.sin_port = port;
    *res = &(ip->info);
    return (0);
    }

    /*
     * Numeric host.
     */
    if (inet_pton(AF_INET, hostname, (void *) &addr) == 1) {
    ip = (struct ipv4addrinfo *) mymalloc(sizeof(*ip));
    init_ipv4addrinfo(ip, socktype);
    ip->sin.sin_addr = addr;
    ip->sin.sin_port = port;
    *res = &(ip->info);
    return (0);
    }

    /*
     * Look up the IPv4 address list.
     */
    if ((hp = gethostbyname(hostname)) == 0)
    return (h_errno == TRY_AGAIN ? EAI_AGAIN : EAI_NODATA);
    if (hp->h_addrtype != AF_INET
    || hp->h_length != sizeof(template.sin.sin_addr))
    return (EAI_NODATA);

    /*
     * Initialize the result template.
     */
    if (template.info.ai_addrlen == 0)
    init_ipv4addrinfo(&template, socktype);

    /*
     * Copy the address information into an addrinfo structure.
     */
    prev = &template;
    for (name_list = hp->h_addr_list; name_list[0]; name_list++) {
    ip = clone_ipv4addrinfo(prev);
    ip->sin.sin_addr = IN_ADDR(name_list[0]);
    ip->sin.sin_port = port;
    if (prev == &template)
        *res = &(ip->info);
    else
        prev->info.ai_next = &(ip->info);
    prev = ip;
    }
    return (0);
#else

    /*
     * Native getaddrinfo(3) version.
     * 
     * XXX Wild-card listener issues.
     * 
     * With most IPv4 plus IPv6 systems, an IPv6 wild-card listener also listens
     * on the IPv4 wild-card address. Connections from IPv4 clients appear as
     * IPv4-in-IPv6 addresses; when Postfix support for IPv4 is turned on,
     * Postfix automatically maps these embedded addresses to their original
     * IPv4 form. So everything seems to be fine.
     * 
     * However, some applications prefer to use separate listener sockets for
     * IPv4 and IPv6. The Postfix IPv6 patch provided such an example. And
     * this is where things become tricky. On many systems the IPv6 and IPv4
     * wild-card listeners cannot coexist. When one is already active, the
     * other fails with EADDRINUSE. Solaris 9, however, will automagically
     * "do the right thing" and allow both listeners to coexist.
     * 
     * Recent systems have the IPV6_V6ONLY feature (RFC 3493), which tells the
     * system that we really mean IPv6 when we say IPv6. This allows us to
     * set up separate wild-card listener sockets for IPv4 and IPv6. So
     * everything seems to be fine again.
     * 
     * The following workaround disables the wild-card IPv4 listener when
     * IPV6_V6ONLY is unavailable. This is necessary for some Linux versions,
     * but is not needed for Solaris 9 (which allows IPv4 and IPv6 wild-card
     * listeners to coexist). Solaris 10 beta already has IPV6_V6ONLY.
     * 
     * XXX This workaround obviously breaks if we want to support protocols in
     * addition to IPv6 and IPv4, but it is needed only until IPv6
     * implementations catch up with RFC 3493. A nicer fix is to filter the
     * getaddrinfo() result, and to return a vector of addrinfo pointers to
     * only those types of elements that the caller has expressed interested
     * in.
     * 
     * XXX Vanilla AIX 5.1 getaddrinfo() does not support a null hostname with
     * AI_PASSIVE. And since we don't know how getaddrinfo() manages its
     * memory we can't bypass it for this special case, or freeaddrinfo()
     * might blow up. Instead we turn off IPV6_V6ONLY in inet_listen(), and
     * supply a protocol-dependent hard-coded string value to getaddrinfo()
     * below, so that it will convert into the appropriate wild-card address.
     * 
     * XXX AIX 5.[1-3] getaddrinfo() may return a non-null port when a null
     * service argument is specified.
     */
    struct addrinfo hints;
    int     err;

    memset((void *) &hints, 0, sizeof(hints));
    hints.ai_family = (pf != PF_UNSPEC) ? pf : inet_proto_info()->ai_family;
    hints.ai_socktype = service ? socktype : MAI_SOCKTYPE;
    if (!hostname) {
    hints.ai_flags = AI_PASSIVE;
#if !defined(IPV6_V6ONLY) || defined(BROKEN_AI_PASSIVE_NULL_HOST)
    switch (hints.ai_family) {
    case PF_UNSPEC:
        hints.ai_family = PF_INET6;
#ifdef BROKEN_AI_PASSIVE_NULL_HOST
    case PF_INET6:
        hostname = "::";
        break;
    case PF_INET:
        hostname = "0.0.0.0";
        break;
#endif
    }
#endif
    }
    err = getaddrinfo(hostname, service, &hints, res);
#if defined(BROKEN_AI_NULL_SERVICE)
    if (service == 0 && err == 0) {
    struct addrinfo *r;
    unsigned short *portp;

    for (r = *res; r != 0; r = r->ai_next)
        if (*(portp = SOCK_ADDR_PORTP(r->ai_addr)) != 0)
        *portp = 0;
    }
#endif
    return (err);
#endif
}

/* hostaddr_to_sockaddr - printable address to binary address form */

int     hostaddr_to_sockaddr(const char *hostaddr, const char *service,
                         int socktype, struct addrinfo ** res)
{
#ifdef EMULATE_IPV4_ADDRINFO

    /*
     * Emulated getaddrinfo(3) version.
     */
    struct ipv4addrinfo *ip;
    struct in_addr addr;
    int     port;

    /*
     * Validate the service.
     */
    if (service) {
    if ((port = find_service(service, socktype)) < 0)
        return (EAI_SERVICE);
    } else {
    port = 0;
    socktype = MAI_SOCKTYPE;
    }

    /*
     * No host means INADDR_ANY.
     */
    if (hostaddr == 0) {
    ip = (struct ipv4addrinfo *) mymalloc(sizeof(*ip));
    init_ipv4addrinfo(ip, socktype);
    ip->sin.sin_addr.s_addr = INADDR_ANY;
    ip->sin.sin_port = port;
    *res = &(ip->info);
    return (0);
    }

    /*
     * Deal with bad address forms.
     */
    switch (inet_pton(AF_INET, hostaddr, (void *) &addr)) {
    case 1:                 /* Success */
    break;
    default:                    /* Unparsable */
    return (EAI_NONAME);
    case -1:                    /* See errno */
    return (EAI_SYSTEM);
    }

    /*
     * Initialize the result structure.
     */
    ip = (struct ipv4addrinfo *) mymalloc(sizeof(*ip));
    init_ipv4addrinfo(ip, socktype);

    /*
     * And copy the result.
     */
    ip->sin.sin_addr = addr;
    ip->sin.sin_port = port;
    *res = &(ip->info);

    return (0);
#else

    /*
     * Native getaddrinfo(3) version. See comments in hostname_to_sockaddr().
     * 
     * XXX Vanilla AIX 5.1 getaddrinfo() returns multiple results when
     * converting a printable ipv4 or ipv6 address to socket address with
     * ai_family=PF_UNSPEC, ai_flags=AI_NUMERICHOST, ai_socktype=SOCK_STREAM,
     * ai_protocol=0 or IPPROTO_TCP, and service=0. The workaround is to
     * ignore all but the first result.
     * 
     * XXX AIX 5.[1-3] getaddrinfo() may return a non-null port when a null
     * service argument is specified.
     */
    struct addrinfo hints;
    int     err;

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = inet_proto_info()->ai_family;
    hints.ai_socktype = service ? socktype : MAI_SOCKTYPE;
    hints.ai_flags = AI_NUMERICHOST;
    if (!hostaddr) {
    hints.ai_flags |= AI_PASSIVE;
#if !defined(IPV6_V6ONLY) || defined(BROKEN_AI_PASSIVE_NULL_HOST)
    switch (hints.ai_family) {
    case PF_UNSPEC:
        hints.ai_family = PF_INET6;
#ifdef BROKEN_AI_PASSIVE_NULL_HOST
    case PF_INET6:
        hostaddr = "::";
        break;
    case PF_INET:
        hostaddr = "0.0.0.0";
        break;
#endif
    }
#endif
    }
    err = getaddrinfo(hostaddr, service, &hints, res);
#if defined(BROKEN_AI_NULL_SERVICE)
    if (service == 0 && err == 0) {
    struct addrinfo *r;
    unsigned short *portp;

    for (r = *res; r != 0; r = r->ai_next)
        if (*(portp = SOCK_ADDR_PORTP(r->ai_addr)) != 0)
        *portp = 0;
    }
#endif
    return (err);
#endif
}

/* sockaddr_to_hostaddr - binary address to printable address form */

int     sockaddr_to_hostaddr(const struct sockaddr *sa, SOCKADDR_SIZE salen,
                         MAI_HOSTADDR_STR *hostaddr,
                         MAI_SERVPORT_STR *portnum,
                         int unused_socktype)
{
#ifdef EMULATE_IPV4_ADDRINFO
    char    portbuf[sizeof("65535")];
    ssize_t len;

    /*
     * Emulated getnameinfo(3) version. The buffer length includes the space
     * for the null terminator.
     */
    if (sa->sa_family != AF_INET) {
    errno = EAFNOSUPPORT;
    return (EAI_SYSTEM);
    }
    if (hostaddr != 0) {
    if (inet_ntop(AF_INET, (void *) &(SOCK_ADDR_IN_ADDR(sa)),
              hostaddr->buf, sizeof(hostaddr->buf)) == 0)
        return (EAI_SYSTEM);
    }
    if (portnum != 0) {
    sprintf(portbuf, "%d", ntohs(SOCK_ADDR_IN_PORT(sa)) & 0xffff);
    if ((len = strlen(portbuf)) >= sizeof(portnum->buf)) {
        errno = ENOSPC;
        return (EAI_SYSTEM);
    }
    memcpy(portnum->buf, portbuf, len + 1);
    }
    return (0);
#else
    int     ret;

    /*
     * Native getnameinfo(3) version.
     */
    ret = getnameinfo(sa, salen,
              hostaddr ? hostaddr->buf : (char *) 0,
              hostaddr ? sizeof(hostaddr->buf) : 0,
              portnum ? portnum->buf : (char *) 0,
              portnum ? sizeof(portnum->buf) : 0,
              NI_NUMERICHOST | NI_NUMERICSERV);
    if (hostaddr != 0 && ret == 0 && sa->sa_family == AF_INET6)
    (void) split_at(hostaddr->buf, '%');
    return (ret);
#endif
}

/* sockaddr_to_hostname - binary address to printable hostname */

int     sockaddr_to_hostname(const struct sockaddr *sa, SOCKADDR_SIZE salen,
                         MAI_HOSTNAME_STR *hostname,
                         MAI_SERVNAME_STR *service,
                         int socktype)
{
#ifdef EMULATE_IPV4_ADDRINFO

    /*
     * Emulated getnameinfo(3) version.
     */
    struct hostent *hp;
    struct servent *sp;
    size_t  len;

    /*
     * Sanity check.
     */
    if (sa->sa_family != AF_INET)
    return (EAI_NODATA);

    /*
     * Look up the host name.
     */
    if (hostname != 0) {
    if ((hp = gethostbyaddr((char *) &(SOCK_ADDR_IN_ADDR(sa)),
                sizeof(SOCK_ADDR_IN_ADDR(sa)),
                AF_INET)) == 0)
        return (h_errno == TRY_AGAIN ? EAI_AGAIN : EAI_NONAME);

    /*
     * Save the result. The buffer length includes the space for the null
     * terminator. Hostname sanity checks are at the end of this
     * function.
     */
    if ((len = strlen(hp->h_name)) >= sizeof(hostname->buf)) {
        errno = ENOSPC;
        return (EAI_SYSTEM);
    }
    memcpy(hostname->buf, hp->h_name, len + 1);
    }

    /*
     * Look up the service.
     */
    if (service != 0) {
    if ((sp = getservbyport(ntohs(SOCK_ADDR_IN_PORT(sa)),
                  socktype == SOCK_DGRAM ? "udp" : "tcp")) == 0)
        return (EAI_NONAME);

    /*
     * Save the result. The buffer length includes the space for the null
     * terminator.
     */
    if ((len = strlen(sp->s_name)) >= sizeof(service->buf)) {
        errno = ENOSPC;
        return (EAI_SYSTEM);
    }
    memcpy(service->buf, sp->s_name, len + 1);
    }
#else

    /*
     * Native getnameinfo(3) version.
     */
    int     err;

    err = getnameinfo(sa, salen,
              hostname ? hostname->buf : (char *) 0,
              hostname ? sizeof(hostname->buf) : 0,
              service ? service->buf : (char *) 0,
              service ? sizeof(service->buf) : 0,
              socktype == SOCK_DGRAM ?
              NI_NAMEREQD | NI_DGRAM : NI_NAMEREQD);
    if (err != 0)
    return (err);
#endif

    /*
     * Hostname sanity checks.
     */
    if (hostname != 0) {
    if (valid_hostaddr(hostname->buf, DONT_GRIPE)) {
        msg_warn("numeric hostname: %s", hostname->buf);
        return (EAI_NONAME);
    }
    if (!valid_hostname(hostname->buf, DO_GRIPE))
        return (EAI_NONAME);
    }
    return (0);
}

/* myaddrinfo_control - fine control */

void    myaddrinfo_control(int name,...)
{
    const char *myname = "myaddrinfo_control";
    va_list ap;

    for (va_start(ap, name); name != 0; name = va_arg(ap, int)) {
    switch (name) {
    default:
        msg_panic("%s: bad name %d", myname, name);
    }
    }
    va_end(ap);
}

#ifdef EMULATE_IPV4_ADDRINFO

/* freeaddrinfo - release storage */

void    freeaddrinfo(struct addrinfo * ai)
{
    struct addrinfo *ap;
    struct addrinfo *next;

    /*
     * Artefact of implementation: tolerate a null pointer argument.
     */
    for (ap = ai; ap != 0; ap = next) {
    next = ap->ai_next;
    if (ap->ai_canonname)
        myfree(ap->ai_canonname);
    /* ap->ai_addr is allocated within this memory block */
    myfree((void *) ap);
    }
}

static char *ai_errlist[] = {
    "Success",
    "Address family for hostname not supported",    /* EAI_ADDRFAMILY */
    "Temporary failure in name resolution", /* EAI_AGAIN     */
    "Invalid value for ai_flags",   /* EAI_BADFLAGS   */
    "Non-recoverable failure in name resolution",   /* EAI_FAIL  */
    "ai_family not supported",      /* EAI_FAMILY     */
    "Memory allocation failure",    /* EAI_MEMORY     */
    "No address associated with hostname",  /* EAI_NODATA     */
    "hostname nor servname provided, or not known", /* EAI_NONAME     */
    "service name not supported for ai_socktype",   /* EAI_SERVICE    */
    "ai_socktype not supported",    /* EAI_SOCKTYPE   */
    "System error returned in errno",   /* EAI_SYSTEM     */
    "Invalid value for hints",      /* EAI_BADHINTS   */
    "Resolved protocol is unknown", /* EAI_PROTOCOL   */
    "Unknown error",            /* EAI_MAX    */
};

/* gai_strerror - error number to string */

char   *gai_strerror(int ecode)
{

    /*
     * Note: EAI_SYSTEM errors are not automatically handed over to
     * strerror(). The application decides.
     */
    if (ecode < 0 || ecode > EAI_MAX)
    ecode = EAI_MAX;
    return (ai_errlist[ecode]);
}

#endif

#ifdef TEST

 /*
  * A test program that takes some info from the command line and runs it
  * forward and backward through the above conversion routines.
  */
#include <stdlib.h>
#include <msg.h>
#include <vstream.h>
#include <msg_vstream.h>

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)
{
    struct addrinfo *info;
    struct addrinfo *ip;
    struct addrinfo **resv;
    MAI_HOSTNAME_STR host;
    MAI_HOSTADDR_STR addr;
    size_t  len, n;
    int     err;

    msg_vstream_init(argv[0], VSTREAM_ERR);

    if (argc != 4)
    msg_fatal("usage: %s protocols hostname hostaddress", argv[0]);

    inet_proto_init(argv[0], argv[1]);

    msg_info("=== hostname %s ===", argv[2]);

    if ((err = hostname_to_sockaddr(argv[2], (char *) 0, 0, &info)) != 0) {
    msg_info("hostname_to_sockaddr(%s): %s",
      argv[2], err == EAI_SYSTEM ? strerror(errno) : gai_strerror(err));
    } else {
    for (len = 0, ip = info; ip != 0; ip = ip->ai_next)
        len += 1;
    resv = (struct addrinfo **) mymalloc(len * sizeof(*resv));
    for (len = 0, ip = info; ip != 0; ip = ip->ai_next)
        resv[len++] = ip;
    qsort((void *) resv, len, sizeof(*resv), compare_family);
    for (n = 0; n < len; n++) {
        ip = resv[n];
        if ((err = sockaddr_to_hostaddr(ip->ai_addr, ip->ai_addrlen, &addr,
                     (MAI_SERVPORT_STR *) 0, 0)) != 0) {
        msg_info("sockaddr_to_hostaddr: %s",
           err == EAI_SYSTEM ? strerror(errno) : gai_strerror(err));
        continue;
        }
        msg_info("%s -> family=%d sock=%d proto=%d %s", argv[2],
         ip->ai_family, ip->ai_socktype, ip->ai_protocol, addr.buf);
        if ((err = sockaddr_to_hostname(ip->ai_addr, ip->ai_addrlen, &host,
                     (MAI_SERVNAME_STR *) 0, 0)) != 0) {
        msg_info("sockaddr_to_hostname: %s",
           err == EAI_SYSTEM ? strerror(errno) : gai_strerror(err));
        continue;
        }
        msg_info("%s -> %s", addr.buf, host.buf);
    }
    freeaddrinfo(info);
    myfree((void *) resv);
    }

    msg_info("=== host address %s ===", argv[3]);

    if ((err = hostaddr_to_sockaddr(argv[3], (char *) 0, 0, &ip)) != 0) {
    msg_info("hostaddr_to_sockaddr(%s): %s",
      argv[3], err == EAI_SYSTEM ? strerror(errno) : gai_strerror(err));
    } else {
    if ((err = sockaddr_to_hostaddr(ip->ai_addr, ip->ai_addrlen, &addr,
                    (MAI_SERVPORT_STR *) 0, 0)) != 0) {
        msg_info("sockaddr_to_hostaddr: %s",
           err == EAI_SYSTEM ? strerror(errno) : gai_strerror(err));
    } else {
        msg_info("%s -> family=%d sock=%d proto=%d %s", argv[3],
         ip->ai_family, ip->ai_socktype, ip->ai_protocol, addr.buf);
        if ((err = sockaddr_to_hostname(ip->ai_addr, ip->ai_addrlen, &host,
                     (MAI_SERVNAME_STR *) 0, 0)) != 0) {
        msg_info("sockaddr_to_hostname: %s",
           err == EAI_SYSTEM ? strerror(errno) : gai_strerror(err));
        } else
        msg_info("%s -> %s", addr.buf, host.buf);
        freeaddrinfo(ip);
    }
    }
    exit(0);
}

#endif