src/lib/net.c

	net.c revision 8bb311aef8b8a6ddda990414083cecedcea77c09
/* Copyright (c) 1999-2016 Dovecot authors, see the included COPYING file */

#define _GNU_SOURCE /* For Linux's struct ucred */
#include "lib.h"
#include "fd-set-nonblock.h"
#include "time-util.h"
#include "net.h"

#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <sys/un.h>
#include <netinet/tcp.h>
#if defined(HAVE_UCRED_H)
#  include <ucred.h> /* for getpeerucred() */
#elif defined(HAVE_SYS_UCRED_H)
#  include <sys/ucred.h> /* for FreeBSD struct xucred */
#endif

union sockaddr_union {
    struct sockaddr sa;
    struct sockaddr_in sin;
#ifdef HAVE_IPV6
    struct sockaddr_in6 sin6;
#endif
};

union sockaddr_union_unix {
    struct sockaddr sa;
    struct sockaddr_un un;
};

#ifdef HAVE_IPV6
#  define SIZEOF_SOCKADDR(so) ((so).sa.sa_family == AF_INET6 ? \
    sizeof(so.sin6) : sizeof(so.sin))
#else
#  define SIZEOF_SOCKADDR(so) (sizeof(so.sin))
#endif

#if !defined(HAVE_GETPEEREID) && !defined(SO_PEERCRED) && !defined(HAVE_GETPEERUCRED) && defined(MSG_WAITALL) && defined(LOCAL_CREDS)
#  define NEEDS_LOCAL_CREDS 1
#endif

bool net_ip_compare(const struct ip_addr *ip1, const struct ip_addr *ip2)
{
    return net_ip_cmp(ip1, ip2) == 0;
}

int net_ip_cmp(const struct ip_addr *ip1, const struct ip_addr *ip2)
{
    if (ip1->family != ip2->family)
        return ip1->family - ip2->family;

#ifdef HAVE_IPV6
    if (ip1->family == AF_INET6)
        return memcmp(&ip1->u.ip6, &ip2->u.ip6, sizeof(ip1->u.ip6));
#endif

    return memcmp(&ip1->u.ip4, &ip2->u.ip4, sizeof(ip1->u.ip4));
}

unsigned int net_ip_hash(const struct ip_addr *ip)
{
        const unsigned char *p;
    unsigned int len, g, h = 0;

#ifdef HAVE_IPV6
    if (ip->family == AF_INET6) {
        p = ip->u.ip6.s6_addr;
        len = sizeof(ip->u.ip6);
    } else
#endif
    {
        return ip->u.ip4.s_addr;
    }

    for (; len > 0; len--, p++) {
        h = (h << 4) + *p;
        if ((g = h & 0xf0000000UL)) {
            h = h ^ (g >> 24);
            h = h ^ g;
        }
    }

    return h;
}

/* copy IP to sockaddr */
static inline void
sin_set_ip(union sockaddr_union *so, const struct ip_addr *ip)
{
    if (ip == NULL) {
#ifdef HAVE_IPV6
        so->sin6.sin6_family = AF_INET6;
        so->sin6.sin6_addr = in6addr_any;
#else
        so->sin.sin_family = AF_INET;
        so->sin.sin_addr.s_addr = INADDR_ANY;
#endif
        return;
    }

    so->sin.sin_family = ip->family;
#ifdef HAVE_IPV6
    if (ip->family == AF_INET6)
        memcpy(&so->sin6.sin6_addr, &ip->u.ip6, sizeof(ip->u.ip6));
    else
#endif
        memcpy(&so->sin.sin_addr, &ip->u.ip4, sizeof(ip->u.ip4));
}

static inline void
sin_get_ip(const union sockaddr_union *so, struct ip_addr *ip)
{
    /* IP structs may be sent across processes. Clear the whole struct
       first to make sure it won't leak any data across processes. */
    memset(ip, 0, sizeof(*ip));

    ip->family = so->sin.sin_family;

#ifdef HAVE_IPV6
    if (ip->family == AF_INET6)
        memcpy(&ip->u.ip6, &so->sin6.sin6_addr, sizeof(ip->u.ip6));
    else
#endif
    if (ip->family == AF_INET)
        memcpy(&ip->u.ip4, &so->sin.sin_addr, sizeof(ip->u.ip4));
    else
        memset(&ip->u, 0, sizeof(ip->u));
}

static inline void sin_set_port(union sockaddr_union *so, in_port_t port)
{
#ifdef HAVE_IPV6
    if (so->sin.sin_family == AF_INET6)
                so->sin6.sin6_port = htons(port);
    else
#endif
        so->sin.sin_port = htons(port);
}

static inline in_port_t sin_get_port(union sockaddr_union *so)
{
#ifdef HAVE_IPV6
    if (so->sin.sin_family == AF_INET6)
        return ntohs(so->sin6.sin6_port);
#endif
    if (so->sin.sin_family == AF_INET)
        return ntohs(so->sin.sin_port);

    return 0;
}

#ifdef __FreeBSD__
static int
net_connect_ip_full_freebsd(const struct ip_addr *ip, in_port_t port,
                const struct ip_addr *my_ip, int sock_type,
                bool blocking);

static int net_connect_ip_full(const struct ip_addr *ip, in_port_t port,
                   const struct ip_addr *my_ip, int sock_type,
                   bool blocking)
{
    int fd, try;

    for (try = 0;;) {
        fd = net_connect_ip_full_freebsd(ip, port, my_ip, sock_type, blocking);
        if (fd != -1 || ++try == 5 ||
            (errno != EADDRINUSE && errno != EACCES))
            break;
        /*
           This may be just a temporary problem:

           EADDRINUSE: busy
           EACCES: pf may cause this if another connection used
                   the same port recently
        */
    }
    return fd;
}
/* then some kludging: */
#define net_connect_ip_full net_connect_ip_full_freebsd
#endif

static int net_connect_ip_full(const struct ip_addr *ip, in_port_t port,
                   const struct ip_addr *my_ip, int sock_type, bool blocking)
{
    union sockaddr_union so;
    int fd, ret, opt = 1;

    if (my_ip != NULL && ip->family != my_ip->family) {
        i_warning("net_connect_ip(): ip->family != my_ip->family");
                my_ip = NULL;
    }

    /* create the socket */
    memset(&so, 0, sizeof(so));
        so.sin.sin_family = ip->family;
    fd = socket(ip->family, sock_type, 0);

    if (fd == -1) {
        i_error("socket() failed: %m");
        return -1;
    }

    /* set socket options */
    (void)setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
    if (sock_type == SOCK_STREAM)
        (void)setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &opt, sizeof(opt));
    if (!blocking)
        net_set_nonblock(fd, TRUE);

    /* set our own address */
    if (my_ip != NULL) {
        sin_set_ip(&so, my_ip);
        if (bind(fd, &so.sa, SIZEOF_SOCKADDR(so)) == -1) {
            i_error("bind(%s) failed: %m", net_ip2addr(my_ip));
            i_close_fd(&fd);
            return -1;
        }
    }

    /* connect */
    sin_set_ip(&so, ip);
    sin_set_port(&so, port);
    ret = connect(fd, &so.sa, SIZEOF_SOCKADDR(so));

#ifndef WIN32
    if (ret < 0 && errno != EINPROGRESS)
#else
    if (ret < 0 && WSAGetLastError() != WSAEWOULDBLOCK)
#endif
    {
                i_close_fd(&fd);
        return -1;
    }

    return fd;
}
#ifdef __FreeBSD__
#  undef net_connect_ip_full
#endif

int net_connect_ip(const struct ip_addr *ip, in_port_t port,
           const struct ip_addr *my_ip)
{
    return net_connect_ip_full(ip, port, my_ip, SOCK_STREAM, FALSE);
}

int net_connect_ip_blocking(const struct ip_addr *ip, in_port_t port,
                const struct ip_addr *my_ip)
{
    return net_connect_ip_full(ip, port, my_ip, SOCK_STREAM, TRUE);
}

int net_connect_udp(const struct ip_addr *ip, in_port_t port,
                   const struct ip_addr *my_ip)
{
    return net_connect_ip_full(ip, port, my_ip, SOCK_DGRAM, FALSE);
}

int net_try_bind(const struct ip_addr *ip)
{
    union sockaddr_union so;
    int fd;

    /* create the socket */
    memset(&so, 0, sizeof(so));
        so.sin.sin_family = ip->family;
    fd = socket(ip->family, SOCK_STREAM, 0);
    if (fd == -1) {
        i_error("socket() failed: %m");
        return -1;
    }

    sin_set_ip(&so, ip);
    if (bind(fd, &so.sa, SIZEOF_SOCKADDR(so)) == -1) {
        i_close_fd(&fd);
        return -1;
    }
    i_close_fd(&fd);
    return 0;
}

int net_connect_unix(const char *path)
{
    union sockaddr_union_unix sa;
    int fd, ret;

    memset(&sa, 0, sizeof(sa));
    sa.un.sun_family = AF_UNIX;
    if (i_strocpy(sa.un.sun_path, path, sizeof(sa.un.sun_path)) < 0) {
        /* too long path */
#ifdef ENAMETOOLONG
        errno = ENAMETOOLONG;
#else
        errno = EINVAL;
#endif
        return -1;
    }

    /* create the socket */
    fd = socket(PF_UNIX, SOCK_STREAM, 0);
    if (fd == -1) {
        i_error("socket(%s) failed: %m", path);
        return -1;
    }

    net_set_nonblock(fd, TRUE);

    /* connect */
    ret = connect(fd, &sa.sa, sizeof(sa));
    if (ret < 0 && errno != EINPROGRESS) {
                i_close_fd(&fd);
        return -1;
    }

#ifdef NEEDS_LOCAL_CREDS
    {
        int on = 1;
        if (setsockopt(fd, 0, LOCAL_CREDS, &on, sizeof on)) {
            i_error("setsockopt(LOCAL_CREDS) failed: %m");
            return -1;
        }
    }
#endif

    return fd;
}

int net_connect_unix_with_retries(const char *path, unsigned int msecs)
{
    struct timeval start, now;
    int fd;

    if (gettimeofday(&start, NULL) < 0)
        i_panic("gettimeofday() failed: %m");

    do {
        fd = net_connect_unix(path);
        if (fd != -1 || (errno != EAGAIN && errno != ECONNREFUSED))
            break;

        /* busy. wait for a while. */
        usleep(((rand() % 10) + 1) * 10000);
        if (gettimeofday(&now, NULL) < 0)
            i_panic("gettimeofday() failed: %m");
    } while (timeval_diff_msecs(&now, &start) < (int)msecs);
    return fd;
}

void net_disconnect(int fd)
{
    /* FreeBSD's close() fails with ECONNRESET if socket still has unsent
       data in transmit buffer. We don't care. */
    if (close(fd) < 0 && errno != ECONNRESET)
        i_error("net_disconnect() failed: %m");
}

void net_set_nonblock(int fd, bool nonblock)
{
    fd_set_nonblock(fd, nonblock);
}

int net_set_cork(int fd ATTR_UNUSED, bool cork ATTR_UNUSED)
{
#ifdef TCP_CORK
    int val = cork;

    return setsockopt(fd, IPPROTO_TCP, TCP_CORK, &val, sizeof(val));
#else
    errno = ENOPROTOOPT;
    return -1;
#endif
}

void net_get_ip_any4(struct ip_addr *ip)
{
    ip->family = AF_INET;
    ip->u.ip4.s_addr = INADDR_ANY;
}

void net_get_ip_any6(struct ip_addr *ip)
{
#ifdef HAVE_IPV6
    ip->family = AF_INET6;
    ip->u.ip6 = in6addr_any;
#else
    memset(ip, 0, sizeof(struct ip_addr));
#endif
}

int net_listen(const struct ip_addr *my_ip, in_port_t *port, int backlog)
{
    enum net_listen_flags flags = 0;

    return net_listen_full(my_ip, port, &flags, backlog);
}

int net_listen_full(const struct ip_addr *my_ip, in_port_t *port,
            enum net_listen_flags *flags, int backlog)
{
    union sockaddr_union so;
    int ret, fd, opt = 1;
    socklen_t len;

    memset(&so, 0, sizeof(so));
    sin_set_port(&so, *port);
    sin_set_ip(&so, my_ip);

    /* create the socket */
    fd = socket(so.sin.sin_family, SOCK_STREAM, 0);
#ifdef HAVE_IPV6
    if (fd == -1 && my_ip == NULL &&
        (errno == EINVAL || errno == EAFNOSUPPORT)) {
        /* IPv6 is not supported by OS */
        so.sin.sin_family = AF_INET;
        so.sin.sin_addr.s_addr = INADDR_ANY;

        fd = socket(AF_INET, SOCK_STREAM, 0);
    }
#endif
    if (fd == -1) {
        i_error("socket() failed: %m");
        return -1;
    }

    /* set socket options */
    (void)setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
    (void)setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &opt, sizeof(opt));

    if ((*flags & NET_LISTEN_FLAG_REUSEPORT) != 0) {
#ifdef SO_REUSEPORT
        if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT,
                   &opt, sizeof(opt)) < 0)
#endif
            *flags &= ~NET_LISTEN_FLAG_REUSEPORT;
    }

    /* If using IPv6, bind only to IPv6 if possible. This avoids
       ambiguities with IPv4-mapped IPv6 addresses. */
#ifdef IPV6_V6ONLY
    if (so.sin.sin_family == AF_INET6) {
        opt = 1;
        (void)setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &opt, sizeof(opt));
    }
#endif
    /* specify the address/port we want to listen in */
    ret = bind(fd, &so.sa, SIZEOF_SOCKADDR(so));
    if (ret < 0) {
        if (errno != EADDRINUSE) {
            i_error("bind(%s, %u) failed: %m",
                my_ip == NULL ? "" : net_ip2addr(my_ip), *port);
        }
    } else {
        /* get the actual port we started listen */
        len = SIZEOF_SOCKADDR(so);
        ret = getsockname(fd, &so.sa, &len);
        if (ret >= 0) {
            *port = sin_get_port(&so);

            /* start listening */
            if (listen(fd, backlog) >= 0)
                return fd;

            if (errno != EADDRINUSE)
                i_error("listen() failed: %m");
        }
    }

        /* error */
    i_close_fd(&fd);
    return -1;
}

int net_listen_unix(const char *path, int backlog)
{
    union {
        struct sockaddr sa;
        struct sockaddr_un un;
    } sa;
    int fd;

    memset(&sa, 0, sizeof(sa));
    sa.un.sun_family = AF_UNIX;
    if (i_strocpy(sa.un.sun_path, path, sizeof(sa.un.sun_path)) < 0) {
        /* too long path */
        errno = EOVERFLOW;
        return -1;
    }

    /* create the socket */
    fd = socket(PF_UNIX, SOCK_STREAM, 0);
    if (fd == -1) {
        i_error("socket() failed: %m");
        return -1;
    }

#ifdef NEEDS_LOCAL_CREDS
    {
        int on = 1;
        if (setsockopt(fd, 0, LOCAL_CREDS, &on, sizeof on)) {
            i_error("setsockopt(LOCAL_CREDS) failed: %m");
            return -1;
        }
    }
#endif

    /* bind */
    if (bind(fd, &sa.sa, sizeof(sa)) < 0) {
        if (errno != EADDRINUSE)
            i_error("bind(%s) failed: %m", path);
    } else {
        /* start listening */
        if (listen(fd, backlog) == 0)
            return fd;

        if (errno != EADDRINUSE)
            i_error("listen() failed: %m");
    }

    i_close_fd(&fd);
    return -1;
}

int net_listen_unix_unlink_stale(const char *path, int backlog)
{
    unsigned int i = 0;
    int fd;

    while ((fd = net_listen_unix(path, backlog)) == -1) {
        if (errno != EADDRINUSE || ++i == 2)
            return -1;

        /* see if it really exists */
        fd = net_connect_unix(path);
        if (fd != -1 || errno != ECONNREFUSED) {
            if (fd != -1) i_close_fd(&fd);
            errno = EADDRINUSE;
            return -1;
        }

        /* delete and try again */
        if (i_unlink_if_exists(path) < 0) {
            errno = EADDRINUSE;
            return -1;
        }
    }
    return fd;
}

int net_accept(int fd, struct ip_addr *addr_r, in_port_t *port_r)
{
    union sockaddr_union so;
    int ret;
    socklen_t addrlen;

    i_assert(fd >= 0);

    addrlen = sizeof(so);
    ret = accept(fd, &so.sa, &addrlen);

    if (ret < 0) {
        if (errno == EAGAIN || errno == ECONNABORTED)
            return -1;
        else
            return -2;
    }
    if (so.sin.sin_family == AF_UNIX) {
        if (addr_r != NULL)
            memset(addr_r, 0, sizeof(*addr_r));
        if (port_r != NULL) *port_r = 0;
    } else {
        if (addr_r != NULL) sin_get_ip(&so, addr_r);
        if (port_r != NULL) *port_r = sin_get_port(&so);
    }
    return ret;
}

ssize_t net_receive(int fd, void *buf, size_t len)
{
    ssize_t ret;

    i_assert(fd >= 0);
    i_assert(len <= SSIZE_T_MAX);

    ret = read(fd, buf, len);
    if (ret == 0) {
        /* disconnected */
        errno = 0;
        return -2;
    }

    if (unlikely(ret < 0)) {
        if (errno == EINTR || errno == EAGAIN)
            return 0;

        if (errno == ECONNRESET || errno == ETIMEDOUT) {
                        /* treat as disconnection */
            return -2;
        }
    }

    return ret;
}

ssize_t net_transmit(int fd, const void *data, size_t len)
{
        ssize_t ret;

    i_assert(fd >= 0);
    i_assert(len <= SSIZE_T_MAX);

    ret = send(fd, data, len, 0);
    if (ret == -1) {
        if (errno == EINTR || errno == EAGAIN)
            return 0;
        if (errno == EPIPE)
            return -2;
    }
        return ret;
}

int net_gethostbyname(const char *addr, struct ip_addr **ips,
              unsigned int *ips_count)
{
    /* @UNSAFE */
#ifdef HAVE_IPV6
    union sockaddr_union *so;
    struct addrinfo hints, *ai, *origai;
    struct ip_addr ip;
    int host_error;
#else
    struct hostent *hp;
#endif
        int count;

    *ips = NULL;
        *ips_count = 0;

#ifdef HAVE_IPV6
    /* support [ipv6] style addresses here so they work globally */
    if (addr[0] == '[' && net_addr2ip(addr, &ip) == 0) {
        *ips_count = 1;
        *ips = t_new(struct ip_addr, 1);
        **ips = ip;
        return 0;
    }

    memset(&hints, 0, sizeof(struct addrinfo));
    hints.ai_socktype = SOCK_STREAM;

    /* save error to host_error for later use */
    host_error = getaddrinfo(addr, NULL, &hints, &ai);
    if (host_error != 0)
        return host_error;

        /* get number of IPs */
        origai = ai;
    for (count = 0; ai != NULL; ai = ai->ai_next)
                count++;

        *ips_count = count;
        *ips = t_malloc(sizeof(struct ip_addr) * count);

        count = 0;
    for (ai = origai; ai != NULL; ai = ai->ai_next, count++) {
        so = (union sockaddr_union *) ai->ai_addr;

        sin_get_ip(so, &(*ips)[count]);
    }
    freeaddrinfo(origai);
#else
    hp = gethostbyname(addr);
    if (hp == NULL)
        return h_errno;

        /* get number of IPs */
    count = 0;
    while (hp->h_addr_list[count] != NULL)
        count++;

        *ips_count = count;
        *ips = t_malloc(sizeof(struct ip_addr) * count);

    while (count > 0) {
        count--;

        (*ips)[count].family = AF_INET;
        memcpy(&(*ips)[count].u.ip4, hp->h_addr_list[count],
               sizeof((*ips)[count].u.ip4));
    }
#endif

    return 0;
}

int net_gethostbyaddr(const struct ip_addr *ip, const char **name_r)
{
    union sockaddr_union so;
    socklen_t addrlen = sizeof(so);
    char hbuf[NI_MAXHOST];
    int ret;

    memset(&so, 0, sizeof(so));
    sin_set_ip(&so, ip);
    ret = getnameinfo(&so.sa, addrlen, hbuf, sizeof(hbuf), NULL, 0,
              NI_NAMEREQD);
    if (ret != 0)
        return ret;

    *name_r = t_strdup(hbuf);
    return 0;
}

int net_getsockname(int fd, struct ip_addr *addr, in_port_t *port)
{
    union sockaddr_union so;
    socklen_t addrlen;

    i_assert(fd >= 0);

    addrlen = sizeof(so);
    if (getsockname(fd, &so.sa, &addrlen) == -1)
        return -1;
    if (so.sin.sin_family == AF_UNIX) {
        if (addr != NULL)
            memset(addr, 0, sizeof(*addr));
        if (port != NULL) *port = 0;
    } else {
        if (addr != NULL) sin_get_ip(&so, addr);
        if (port != NULL) *port = sin_get_port(&so);
    }
    return 0;
}

int net_getpeername(int fd, struct ip_addr *addr, in_port_t *port)
{
    union sockaddr_union so;
    socklen_t addrlen;

    i_assert(fd >= 0);

    addrlen = sizeof(so);
    if (getpeername(fd, &so.sa, &addrlen) == -1)
        return -1;
    if (so.sin.sin_family == AF_UNIX) {
        if (addr != NULL)
            memset(addr, 0, sizeof(*addr));
        if (port != NULL) *port = 0;
    } else {
        if (addr != NULL) sin_get_ip(&so, addr);
        if (port != NULL) *port = sin_get_port(&so);
    }
    return 0;
}

int net_getunixname(int fd, const char **name_r)
{
    union sockaddr_union_unix so;
    socklen_t addrlen = sizeof(so);

    if (getsockname(fd, &so.sa, &addrlen) < 0)
        return -1;
    if (so.un.sun_family != AF_UNIX) {
        errno = ENOTSOCK;
        return -1;
    }
    *name_r = t_strdup(so.un.sun_path);
    return 0;
}

int net_getunixcred(int fd, struct net_unix_cred *cred_r)
{
#if defined(SO_PEERCRED)
# if defined(HAVE_STRUCT_SOCKPEERCRED)
    /* OpenBSD (may also provide getpeereid, but we also want pid) */
    struct sockpeercred ucred;
# else
    /* Linux */
    struct ucred ucred;
# endif
    socklen_t len = sizeof(ucred);

    if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {
        i_error("getsockopt(SO_PEERCRED) failed: %m");
        return -1;
    }
    cred_r->uid = ucred.uid;
    cred_r->gid = ucred.gid;
    cred_r->pid = ucred.pid;
    return 0;
#elif defined(LOCAL_PEEREID)
    /* NetBSD (may also provide getpeereid, but we also want pid) */
    struct unpcbid ucred;
    socklen_t len = sizeof(ucred);

    if (getsockopt(fd, 0, LOCAL_PEEREID, &ucred, &len) < 0) {
        i_error("getsockopt(LOCAL_PEEREID) failed: %m");
        return -1;
    }

    cred_r->uid = ucred.unp_euid;
    cred_r->gid = ucred.unp_egid;
    cred_r->pid = ucred.unp_pid;
    return 0;
#elif defined(HAVE_GETPEEREID)
    /* OSX 10.4+, FreeBSD 4.6+, OpenBSD 3.0+, NetBSD 5.0+ */
    if (getpeereid(fd, &cred_r->uid, &cred_r->gid) < 0) {
        i_error("getpeereid() failed: %m");
        return -1;
    }
    cred_r->pid = (pid_t)-1;
    return 0;
#elif defined(LOCAL_PEERCRED)
    /* Older FreeBSD */
    struct xucred ucred;
    socklen_t len = sizeof(ucred);

    if (getsockopt(fd, 0, LOCAL_PEERCRED, &ucred, &len) < 0) {
        i_error("getsockopt(LOCAL_PEERCRED) failed: %m");
        return -1;
    }

    if (ucred.cr_version != XUCRED_VERSION) {
        errno = EINVAL;
        return -1;
    }

    cred_r->uid = ucred.cr_uid;
    cred_r->gid = ucred.cr_gid;
    cred_r->pid = (pid_t)-1;
    return 0;
#elif defined(HAVE_GETPEERUCRED)
    /* Solaris */
    ucred_t *ucred = NULL;

    if (getpeerucred(fd, &ucred) < 0) {
        i_error("getpeerucred() failed: %m");
        return -1;
    }
    cred_r->uid = ucred_geteuid(ucred);
    cred_r->gid = ucred_getrgid(ucred);
    cred_r->pid = ucred_getpid(ucred);
    ucred_free(ucred);

    if (cred_r->uid == (uid_t)-1 ||
        cred_r->gid == (gid_t)-1) {
        errno = EINVAL;
        return -1;
    }
    return 0;
#elif NEEDS_LOCAL_CREDS
    /* NetBSD < 5 */
    int i, n, on;
    struct iovec iov;
    struct msghdr msg;
    struct {
        struct cmsghdr ch;
        char buf[110];
    } cdata;
    struct sockcred *sc;

    iov.iov_base = (char *)&on;
    iov.iov_len = 1;

    sc = (struct sockcred *)cdata.buf;
    sc->sc_uid = sc->sc_euid = sc->sc_gid = sc->sc_egid = -1;
    memset(&cdata.ch, 0, sizeof cdata.ch);

    memset(&msg, 0, sizeof msg);

    msg.msg_iov = &iov;
    msg.msg_iovlen = 1;
    msg.msg_control = &cdata;
    msg.msg_controllen = sizeof(cdata.ch) + sizeof(cdata.buf);

    for (i = 0; i < 10; i++) {
        n = recvmsg(fd, &msg, MSG_WAITALL | MSG_PEEK);
        if (n >= 0 || errno != EAGAIN)
            break;
        usleep(100);
    }
    if (n < 0) {
        i_error("recvmsg() failed: %m");
        return -1;
    }
    cred_r->uid = sc->sc_euid;
    cred_r->gid = sc->sc_egid;
    cred_r->pid = (pid_t)-1;
    return 0;
#else
    errno = EINVAL;
    return -1;
#endif
}

const char *net_ip2addr(const struct ip_addr *ip)
{
#ifdef HAVE_IPV6
    char addr[MAX_IP_LEN+1];

    addr[MAX_IP_LEN] = '\0';
    if (inet_ntop(ip->family, &ip->u.ip6, addr, MAX_IP_LEN) == NULL)
        return "";

    return t_strdup(addr);
#else
    unsigned long ip4;

    if (ip->family != AF_INET)
        return "";

    ip4 = ntohl(ip->u.ip4.s_addr);
    return t_strdup_printf("%lu.%lu.%lu.%lu",
                   (ip4 & 0xff000000UL) >> 24,
                   (ip4 & 0x00ff0000) >> 16,
                   (ip4 & 0x0000ff00) >> 8,
                   (ip4 & 0x000000ff));
#endif
}

int net_addr2ip(const char *addr, struct ip_addr *ip)
{
    int ret;

    if (strchr(addr, ':') != NULL) {
        /* IPv6 */
#ifdef HAVE_IPV6
        T_BEGIN {
            if (addr[0] == '[') {
                /* allow [ipv6 addr] */
                unsigned int len = strlen(addr);
                if (addr[len-1] == ']')
                    addr = t_strndup(addr+1, len-2);
            }
            ret = inet_pton(AF_INET6, addr, &ip->u.ip6);
        } T_END;
        if (ret == 0)
            return -1;
#else
        ip->u.ip4.s_addr = 0;
#endif
        ip->family = AF_INET6;
    } else {
        /* IPv4 */
        if (inet_aton(addr, &ip->u.ip4) == 0)
            return -1;
        ip->family = AF_INET;
    }
    return 0;
}

int net_str2port(const char *str, in_port_t *port_r)
{
    uintmax_t l;

    if (str_to_uintmax(str, &l) < 0)
        return -1;

    if (l == 0 || l > (in_port_t)-1)
        return -1;
    *port_r = (in_port_t)l;
    return 0;
}

int net_str2port_zero(const char *str, in_port_t *port_r)
{
    uintmax_t l;

    if (str_to_uintmax(str, &l) < 0)
        return -1;

    if (l > (in_port_t)-1)
        return -1;
    *port_r = (in_port_t)l;
    return 0;
}

int net_str2hostport(const char *str, in_port_t default_port,
             const char **host_r, in_port_t *port_r)
{
    const char *p, *host;
    in_port_t port;

    if (str[0] == '[') {
        /* [IPv6] address, possibly followed by :port */
        p = strchr(str, ']');
        if (p == NULL)
            return -1;
        host = t_strdup_until(str+1, p++);
    } else {
        p = strchr(str, ':');
        if (p == NULL || strchr(p+1, ':') != NULL) {
            /* host or IPv6 address */
            *host_r = str;
            *port_r = default_port;
            return 0;
        }
        host = t_strdup_until(str, p);
    }
    if (p[0] == '\0') {
        *host_r = host;
        *port_r = default_port;
        return 0;
    }
    if (p[0] != ':')
        return -1;
    if (net_str2port(p+1, &port) < 0)
        return -1;
    *host_r = host;
    *port_r = port;
    return 0;
}

int net_ipv6_mapped_ipv4_convert(const struct ip_addr *src,
                 struct ip_addr *dest)
{
#ifdef HAVE_IPV6
    static uint8_t v4_prefix[] =
        { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff };

    if (!IPADDR_IS_V6(src))
        return -1;
    if (memcmp(src->u.ip6.s6_addr, v4_prefix, sizeof(v4_prefix)) != 0)
        return -1;

    dest->family = AF_INET;
    memcpy(&dest->u.ip6, &src->u.ip6.s6_addr[3*4], 4);
    return 0;
#else
    return -1;
#endif
}

int net_geterror(int fd)
{
    int data;
    socklen_t len = sizeof(data);

    if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &data, &len) == -1) {
        /* we're now really returning the getsockopt()'s error code
           instead of the socket's, but normally we should never get
           here anyway. */
        return errno;
    }

    return data;
}

const char *net_gethosterror(int error)
{
#ifdef HAVE_IPV6
    i_assert(error != 0);

    return gai_strerror(error);
#else
    switch (error) {
    case HOST_NOT_FOUND:
        return "Host not found";
    case NO_ADDRESS:
        return "No IP address found for name";
    case NO_RECOVERY:
        return "A non-recoverable name server error occurred";
    case TRY_AGAIN:
        return "A temporary error on an authoritative name server";
    default:
        return t_strdup_printf("Unknown error %d", error);
    }
#endif
}

int net_hosterror_notfound(int error)
{
#ifdef HAVE_IPV6
#ifdef EAI_NODATA /* NODATA is depricated */
    return error != 1 && (error == EAI_NONAME || error == EAI_NODATA);
#else
    return error != 1 && (error == EAI_NONAME);
#endif
#else
    return error == HOST_NOT_FOUND || error == NO_ADDRESS;
#endif
}

const char *net_getservbyport(in_port_t port)
{
    struct servent *entry;

    entry = getservbyport(htons(port), "tcp");
    return entry == NULL ? NULL : entry->s_name;
}

bool is_ipv4_address(const char *addr)
{
    while (*addr != '\0') {
        if (*addr != '.' && !i_isdigit(*addr))
            return FALSE;
                addr++;
    }

    return TRUE;
}

bool is_ipv6_address(const char *addr)
{
    bool have_prefix = FALSE;

    if (*addr == '[') {
        have_prefix = TRUE;
        addr++;
    }
    while (*addr != '\0') {
        if (*addr != ':' && !i_isxdigit(*addr)) {
            if (have_prefix && *addr == ']' && addr[1] == '\0')
                break;
            return FALSE;
        }
                addr++;
    }

    return TRUE;
}

int net_parse_range(const char *network, struct ip_addr *ip_r,
            unsigned int *bits_r)
{
    const char *p;
    unsigned int bits, max_bits;

    p = strchr(network, '/');
    if (p != NULL)
        network = t_strdup_until(network, p++);

    if (net_addr2ip(network, ip_r) < 0)
        return -1;

    max_bits = IPADDR_BITS(ip_r);
    if (p == NULL) {
        /* full IP address must match */
        bits = max_bits;
    } else {
        /* get the network mask */
        if (str_to_uint(p, &bits) < 0 || bits > max_bits)
            return -1;
    }
    *bits_r = bits;
    return 0;
}

bool net_is_in_network(const struct ip_addr *ip,
               const struct ip_addr *net_ip, unsigned int bits)
{
    struct ip_addr tmp_ip;
    const uint32_t *ip1, *ip2;
    uint32_t mask, i1, i2;
    unsigned int pos, i;

    if (net_ipv6_mapped_ipv4_convert(ip, &tmp_ip) == 0) {
        /* IPv4 address mapped disguised as IPv6 address */
        ip = &tmp_ip;
    }

    if (ip->family == 0 || net_ip->family == 0) {
        /* non-IPv4/IPv6 address (e.g. UNIX socket) never matches
           anything */
        return FALSE;
    }
    if (IPADDR_IS_V4(ip) != IPADDR_IS_V4(net_ip)) {
        /* one is IPv6 and one is IPv4 */
        return FALSE;
    }
    i_assert(IPADDR_IS_V6(ip) == IPADDR_IS_V6(net_ip));

    if (IPADDR_IS_V4(ip)) {
        ip1 = &ip->u.ip4.s_addr;
        ip2 = &net_ip->u.ip4.s_addr;
    } else {
#ifdef HAVE_IPV6
        ip1 = (const void *)&ip->u.ip6;
        ip2 = (const void *)&net_ip->u.ip6;
#else
        /* shouldn't get here */
        return FALSE;
#endif
    }

    /* check first the full 32bit ints */
    for (pos = 0, i = 0; pos + 32 <= bits; pos += 32, i++) {
        if (ip1[i] != ip2[i])
            return FALSE;
    }
    i1 = htonl(ip1[i]);
    i2 = htonl(ip2[i]);

    /* check the last full bytes */
    for (mask = 0xff000000; pos + 8 <= bits; pos += 8, mask >>= 8) {
        if ((i1 & mask) != (i2 & mask))
            return FALSE;
    }

    /* check the last bits, they're reversed in bytes */
    bits -= pos;
    for (mask = 0x80000000 >> (pos % 32); bits > 0; bits--, mask >>= 1) {
        if ((i1 & mask) != (i2 & mask))
            return FALSE;
    }
    return TRUE;
}