getaddrinfo.c

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/*-------------------------------------------------------------------------
 *
 * getaddrinfo.c
 *    Support getaddrinfo() on platforms that don't have it.
 *
 * We also supply getnameinfo() here, assuming that the platform will have
 * it if and only if it has getaddrinfo().  If this proves false on some
 * platform, we'll need to split this file and provide a separate configure
 * test for getnameinfo().
 *
 * Windows may or may not have these routines, so we handle Windows specially
 * by dynamically checking for their existence.  If they already exist, we
 * use the Windows native routines, but if not, we use our own.
 *
 *
 * Copyright (c) 2003-2020, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/port/getaddrinfo.c
 *
 *-------------------------------------------------------------------------
 */

/* This is intended to be used in both frontend and backend, so use c.h */
#include "c.h"

#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "getaddrinfo.h"
#include "libpq/pqcomm.h"       /* needed for struct sockaddr_storage */
#include "port/pg_bswap.h"


#ifdef WIN32
/*
 * The native routines may or may not exist on the Windows platform we are on,
 * so we dynamically look up the routines, and call them via function pointers.
 * Here we need to declare what the function pointers look like
 */
typedef int (__stdcall * getaddrinfo_ptr_t) (const char *nodename,
                                             const char *servname,
                                             const struct addrinfo *hints,
                                             struct addrinfo **res);

typedef void (__stdcall * freeaddrinfo_ptr_t) (struct addrinfo *ai);

typedef int (__stdcall * getnameinfo_ptr_t) (const struct sockaddr *sa,
                                             int salen,
                                             char *node, int nodelen,
                                             char *service, int servicelen,
                                             int flags);

/* static pointers to the native routines, so we only do the lookup once. */
static getaddrinfo_ptr_t getaddrinfo_ptr = NULL;
static freeaddrinfo_ptr_t freeaddrinfo_ptr = NULL;
static getnameinfo_ptr_t getnameinfo_ptr = NULL;


static bool
haveNativeWindowsIPv6routines(void)
{
    void       *hLibrary = NULL;
    static bool alreadyLookedForIpv6routines = false;

    if (alreadyLookedForIpv6routines)
        return (getaddrinfo_ptr != NULL);

    /*
     * For Windows XP and later versions, the IPv6 routines are present in the
     * WinSock 2 library (ws2_32.dll).
     */
    hLibrary = LoadLibraryA("ws2_32");

    /* If hLibrary is null, we couldn't find a dll with functions */
    if (hLibrary != NULL)
    {
        /* We found a dll, so now get the addresses of the routines */

        getaddrinfo_ptr = (getaddrinfo_ptr_t) GetProcAddress(hLibrary,
                                                             "getaddrinfo");
        freeaddrinfo_ptr = (freeaddrinfo_ptr_t) GetProcAddress(hLibrary,
                                                               "freeaddrinfo");
        getnameinfo_ptr = (getnameinfo_ptr_t) GetProcAddress(hLibrary,
                                                             "getnameinfo");

        /*
         * If any one of the routines is missing, let's play it safe and
         * ignore them all
         */
        if (getaddrinfo_ptr == NULL ||
            freeaddrinfo_ptr == NULL ||
            getnameinfo_ptr == NULL)
        {
            FreeLibrary(hLibrary);
            hLibrary = NULL;
            getaddrinfo_ptr = NULL;
            freeaddrinfo_ptr = NULL;
            getnameinfo_ptr = NULL;
        }
    }

    alreadyLookedForIpv6routines = true;
    return (getaddrinfo_ptr != NULL);
}
#endif


/*
 * get address info for ipv4 sockets.
 *
 *  Bugs:   - only one addrinfo is set even though hintp is NULL or
 *        ai_socktype is 0
 *      - AI_CANONNAME is not supported.
 *      - servname can only be a number, not text.
 */
int
getaddrinfo(const char *node, const char *service,
            const struct addrinfo *hintp,
            struct addrinfo **res)
{
    struct addrinfo *ai;
    struct sockaddr_in sin,
               *psin;
    struct addrinfo hints;

#ifdef WIN32

    /*
     * If Windows has native IPv6 support, use the native Windows routine.
     * Otherwise, fall through and use our own code.
     */
    if (haveNativeWindowsIPv6routines())
        return (*getaddrinfo_ptr) (node, service, hintp, res);
#endif

    if (hintp == NULL)
    {
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = AF_INET;
        hints.ai_socktype = SOCK_STREAM;
    }
    else
        memcpy(&hints, hintp, sizeof(hints));

    if (hints.ai_family != AF_INET && hints.ai_family != AF_UNSPEC)
        return EAI_FAMILY;

    if (hints.ai_socktype == 0)
        hints.ai_socktype = SOCK_STREAM;

    if (!node && !service)
        return EAI_NONAME;

    memset(&sin, 0, sizeof(sin));

    sin.sin_family = AF_INET;

    if (node)
    {
        if (node[0] == '\0')
            sin.sin_addr.s_addr = pg_hton32(INADDR_ANY);
        else if (hints.ai_flags & AI_NUMERICHOST)
        {
            if (!inet_aton(node, &sin.sin_addr))
                return EAI_NONAME;
        }
        else
        {
            struct hostent *hp;

#ifdef FRONTEND
            struct hostent hpstr;
            char        buf[BUFSIZ];
            int         herrno = 0;

            pqGethostbyname(node, &hpstr, buf, sizeof(buf),
                            &hp, &herrno);
#else
            hp = gethostbyname(node);
#endif
            if (hp == NULL)
            {
                switch (h_errno)
                {
                    case HOST_NOT_FOUND:
                    case NO_DATA:
                        return EAI_NONAME;
                    case TRY_AGAIN:
                        return EAI_AGAIN;
                    case NO_RECOVERY:
                    default:
                        return EAI_FAIL;
                }
            }
            if (hp->h_addrtype != AF_INET)
                return EAI_FAIL;

            memcpy(&(sin.sin_addr), hp->h_addr, hp->h_length);
        }
    }
    else
    {
        if (hints.ai_flags & AI_PASSIVE)
            sin.sin_addr.s_addr = pg_hton32(INADDR_ANY);
        else
            sin.sin_addr.s_addr = pg_hton32(INADDR_LOOPBACK);
    }

    if (service)
        sin.sin_port = pg_hton16((unsigned short) atoi(service));

#ifdef HAVE_STRUCT_SOCKADDR_STORAGE_SS_LEN
    sin.sin_len = sizeof(sin);
#endif

    ai = malloc(sizeof(*ai));
    if (!ai)
        return EAI_MEMORY;

    psin = malloc(sizeof(*psin));
    if (!psin)
    {
        free(ai);
        return EAI_MEMORY;
    }

    memcpy(psin, &sin, sizeof(*psin));

    ai->ai_flags = 0;
    ai->ai_family = AF_INET;
    ai->ai_socktype = hints.ai_socktype;
    ai->ai_protocol = hints.ai_protocol;
    ai->ai_addrlen = sizeof(*psin);
    ai->ai_addr = (struct sockaddr *) psin;
    ai->ai_canonname = NULL;
    ai->ai_next = NULL;

    *res = ai;

    return 0;
}


void
freeaddrinfo(struct addrinfo *res)
{
    if (res)
    {
#ifdef WIN32

        /*
         * If Windows has native IPv6 support, use the native Windows routine.
         * Otherwise, fall through and use our own code.
         */
        if (haveNativeWindowsIPv6routines())
        {
            (*freeaddrinfo_ptr) (res);
            return;
        }
#endif

        if (res->ai_addr)
            free(res->ai_addr);
        free(res);
    }
}


const char *
gai_strerror(int errcode)
{
#ifdef HAVE_HSTRERROR
    int         hcode;

    switch (errcode)
    {
        case EAI_NONAME:
            hcode = HOST_NOT_FOUND;
            break;
        case EAI_AGAIN:
            hcode = TRY_AGAIN;
            break;
        case EAI_FAIL:
        default:
            hcode = NO_RECOVERY;
            break;
    }

    return hstrerror(hcode);
#else                           /* !HAVE_HSTRERROR */

    switch (errcode)
    {
        case EAI_NONAME:
            return "Unknown host";
        case EAI_AGAIN:
            return "Host name lookup failure";
            /* Errors below are probably WIN32 only */
#ifdef EAI_BADFLAGS
        case EAI_BADFLAGS:
            return "Invalid argument";
#endif
#ifdef EAI_FAMILY
        case EAI_FAMILY:
            return "Address family not supported";
#endif
#ifdef EAI_MEMORY
        case EAI_MEMORY:
            return "Not enough memory";
#endif
#if defined(EAI_NODATA) && EAI_NODATA != EAI_NONAME /* MSVC/WIN64 duplicate */
        case EAI_NODATA:
            return "No host data of that type was found";
#endif
#ifdef EAI_SERVICE
        case EAI_SERVICE:
            return "Class type not found";
#endif
#ifdef EAI_SOCKTYPE
        case EAI_SOCKTYPE:
            return "Socket type not supported";
#endif
        default:
            return "Unknown server error";
    }
#endif                          /* HAVE_HSTRERROR */
}

/*
 * Convert an ipv4 address to a hostname.
 *
 * Bugs:    - Only supports NI_NUMERICHOST and NI_NUMERICSERV behavior.
 *        It will never resolve a hostname.
 *      - No IPv6 support.
 */
int
getnameinfo(const struct sockaddr *sa, int salen,
            char *node, int nodelen,
            char *service, int servicelen, int flags)
{
#ifdef WIN32

    /*
     * If Windows has native IPv6 support, use the native Windows routine.
     * Otherwise, fall through and use our own code.
     */
    if (haveNativeWindowsIPv6routines())
        return (*getnameinfo_ptr) (sa, salen, node, nodelen,
                                   service, servicelen, flags);
#endif

    /* Invalid arguments. */
    if (sa == NULL || (node == NULL && service == NULL))
        return EAI_FAIL;

#ifdef  HAVE_IPV6
    if (sa->sa_family == AF_INET6)
        return EAI_FAMILY;
#endif

    /* Unsupported flags. */
    if (flags & NI_NAMEREQD)
        return EAI_AGAIN;

    if (node)
    {
        if (sa->sa_family == AF_INET)
        {
            if (pg_inet_net_ntop(AF_INET,
                                 &((struct sockaddr_in *) sa)->sin_addr,
                                 sa->sa_family == AF_INET ? 32 : 128,
                                 node, nodelen) == NULL)
                return EAI_MEMORY;
        }
        else
            return EAI_MEMORY;
    }

    if (service)
    {
        int         ret = -1;

        if (sa->sa_family == AF_INET)
        {
            ret = snprintf(service, servicelen, "%d",
                           pg_ntoh16(((struct sockaddr_in *) sa)->sin_port));
        }
        if (ret < 0 || ret >= servicelen)
            return EAI_MEMORY;
    }

    return 0;
}