src/director/mail-host.c

	mail-host.c revision eb209d12e3b1cfed564c35cf19fdb1bf7fcc6811
/* Copyright (c) 2010-2014 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "bsearch-insert-pos.h"
#include "md5.h"
#include "mail-host.h"

#define VHOST_MULTIPLIER 100

struct mail_vhost {
    unsigned int hash;
    struct mail_host *host;
};

struct mail_host_list {
    ARRAY_TYPE(mail_host) hosts;
    ARRAY(struct mail_vhost) vhosts;
    bool hosts_unsorted;
    bool consistent_hashing;
};

static int
mail_host_cmp(struct mail_host *const *h1, struct mail_host *const *h2)
{
    return net_ip_cmp(&(*h1)->ip, &(*h2)->ip);
}

static int
mail_vhost_cmp(const struct mail_vhost *h1, const struct mail_vhost *h2)
{
    if (h1->hash < h2->hash)
        return -1;
    else if (h1->hash > h2->hash)
        return 1;
    /* hash collision. not ideal, but we'll need to keep the order
       consistent across directors so compare the IPs next. */
    return net_ip_cmp(&h1->host->ip, &h2->host->ip);
}

static int
mail_vhost_hash_cmp(const unsigned int *hash, const struct mail_vhost *vhost)
{
    if (vhost->hash < *hash)
        return 1;
    else if (vhost->hash > *hash)
        return -1;
    else
        return 0;
}

static void mail_vhost_add(struct mail_host_list *list, struct mail_host *host)
{
    struct mail_vhost *vhost;
    struct md5_context md5_ctx, md5_ctx2;
    unsigned char md5[MD5_RESULTLEN];
    const char *ip_str;
    char num_str[MAX_INT_STRLEN];
    unsigned int i, j;

    ip_str = net_ip2addr(&host->ip);

    md5_init(&md5_ctx);
    md5_update(&md5_ctx, ip_str, strlen(ip_str));

    for (i = 0; i < host->vhost_count; i++) {
        md5_ctx2 = md5_ctx;
        i_snprintf(num_str, sizeof(num_str), "-%u", i);
        md5_update(&md5_ctx2, num_str, strlen(num_str));
        md5_final(&md5_ctx2, md5);

        vhost = array_append_space(&list->vhosts);
        vhost->host = host;
        for (j = 0; j < sizeof(vhost->hash); j++)
            vhost->hash = (vhost->hash << CHAR_BIT) | md5[j];
    }
}

static void mail_hosts_sort_ring(struct mail_host_list *list)
{
    struct mail_host *const *hostp;

    /* rebuild vhosts */
    array_clear(&list->vhosts);
    array_foreach(&list->hosts, hostp)
        mail_vhost_add(list, *hostp);
    array_sort(&list->vhosts, mail_vhost_cmp);
    list->hosts_unsorted = FALSE;
}

static void mail_hosts_sort_direct(struct mail_host_list *list)
{
    struct mail_vhost *vhost;
    struct mail_host *const *hostp;
    unsigned int i;

    array_sort(&list->hosts, mail_host_cmp);

    /* rebuild vhosts */
    array_clear(&list->vhosts);
    array_foreach(&list->hosts, hostp) {
        for (i = 0; i < (*hostp)->vhost_count; i++) {
            vhost = array_append_space(&list->vhosts);
            vhost->host = *hostp;
        }
    }
    list->hosts_unsorted = FALSE;
}

static void mail_hosts_sort(struct mail_host_list *list)
{
    if (list->consistent_hashing)
        mail_hosts_sort_ring(list);
    else
        mail_hosts_sort_direct(list);
}

struct mail_host *
mail_host_add_ip(struct mail_host_list *list, const struct ip_addr *ip)
{
    struct mail_host *host;

    host = i_new(struct mail_host, 1);
    host->vhost_count = VHOST_MULTIPLIER;
    host->ip = *ip;
    array_append(&list->hosts, &host, 1);

    list->hosts_unsorted = TRUE;
    return host;
}

static int mail_host_add(struct mail_host_list *list, const char *host)
{
    struct ip_addr *ips;
    unsigned int i, ips_count;

    if (net_gethostbyname(host, &ips, &ips_count) < 0) {
        i_error("Unknown mail host: %s", host);
        return -1;
    }

    for (i = 0; i < ips_count; i++)
        (void)mail_host_add_ip(list, &ips[i]);
    return 0;
}

static int
mail_hosts_add_range(struct mail_host_list *list,
             struct ip_addr ip1, struct ip_addr ip2)
{
    uint32_t *ip1_arr, *ip2_arr;
    uint32_t i1, i2;
    unsigned int i, j, max_bits, last_bits;

    if (ip1.family != ip2.family) {
        i_error("IP address family mismatch: %s vs %s",
            net_ip2addr(&ip1), net_ip2addr(&ip2));
        return -1;
    }
    if (net_ip_cmp(&ip1, &ip2) > 0) {
        i_error("IP addresses reversed: %s-%s",
            net_ip2addr(&ip1), net_ip2addr(&ip2));
        return -1;
    }
    if (IPADDR_IS_V4(&ip1)) {
        ip1_arr = &ip1.u.ip4.s_addr;
        ip2_arr = &ip2.u.ip4.s_addr;
        max_bits = 32;
        last_bits = 8;
    } else {
#ifndef HAVE_IPV6
        i_error("IPv6 not supported");
        return -1;
#else
        ip1_arr = (void *)&ip1.u.ip6;
        ip2_arr = (void *)&ip2.u.ip6;
        max_bits = 128;
        last_bits = 16;
#endif
    }

    /* make sure initial bits match */
    for (i = 0; i < (max_bits-last_bits)/32; i++) {
        if (ip1_arr[i] != ip2_arr[i]) {
            i_error("IP address range too large: %s-%s",
                net_ip2addr(&ip1), net_ip2addr(&ip2));
            return -1;
        }
    }
    i1 = htonl(ip1_arr[i]);
    i2 = htonl(ip2_arr[i]);

    for (j = last_bits; j < 32; j++) {
        if ((i1 & (1U << j)) != (i2 & (1U << j))) {
            i_error("IP address range too large: %s-%s",
                net_ip2addr(&ip1), net_ip2addr(&ip2));
            return -1;
        }
    }

    /* create hosts from the final bits */
    do {
        ip1_arr[i] = ntohl(i1);
        (void)mail_host_add_ip(list, &ip1);
        i1++;
    } while (ip1_arr[i] != ip2_arr[i]);
    return 0;
}

int mail_hosts_parse_and_add(struct mail_host_list *list,
                 const char *hosts_string)
{
    int ret = 0;

    T_BEGIN {
        const char *const *tmp, *p, *host1, *host2;
        struct ip_addr ip1, ip2;

        tmp = t_strsplit_spaces(hosts_string, " ");
        for (; *tmp != NULL; tmp++) {
            p = strchr(*tmp, '-');
            if (p != NULL) {
                /* see if this is ip1-ip2 range */
                host1 = t_strdup_until(*tmp, p);
                host2 = p + 1;
                if (net_addr2ip(host1, &ip1) == 0 &&
                    net_addr2ip(host2, &ip2) == 0) {
                    if (mail_hosts_add_range(list, ip1,
                                 ip2) < 0)
                        ret = -1;
                    continue;
                }
            }

            if (mail_host_add(list, *tmp) < 0)
                ret = -1;
        }
    } T_END;

    if (array_count(&list->hosts) == 0) {
        if (ret < 0)
            i_error("No valid servers specified");
        else
            i_error("Empty server list");
        ret = -1;
    }
    return ret;
}

void mail_host_set_vhost_count(struct mail_host_list *list,
                   struct mail_host *host, unsigned int vhost_count)
{
    host->vhost_count = vhost_count;
    list->hosts_unsorted = TRUE;
}

void mail_host_remove(struct mail_host_list *list, struct mail_host *host)
{
    struct mail_host *const *hosts;
    unsigned int i, count;

    hosts = array_get(&list->hosts, &count);
    for (i = 0; i < count; i++) {
        if (hosts[i] == host) {
            array_delete(&list->hosts, i, 1);
            break;
        }
    }

    i_free(host);
    list->hosts_unsorted = TRUE;
}

struct mail_host *
mail_host_lookup(struct mail_host_list *list, const struct ip_addr *ip)
{
    struct mail_host *const *hostp;

    if (list->hosts_unsorted)
        mail_hosts_sort(list);

    array_foreach(&list->hosts, hostp) {
        if (net_ip_compare(&(*hostp)->ip, ip))
            return *hostp;
    }
    return NULL;
}

static struct mail_host *
mail_host_get_by_hash_ring(struct mail_host_list *list, unsigned int hash)
{
    const struct mail_vhost *vhosts;
    unsigned int count, idx;

    vhosts = array_get(&list->vhosts, &count);
    array_bsearch_insert_pos(&list->vhosts, &hash,
                 mail_vhost_hash_cmp, &idx);
    if (idx == count) {
        if (count == 0)
            return NULL;
        idx = 0;
    }

    return vhosts[idx].host;
}

static struct mail_host *
mail_host_get_by_hash_direct(struct mail_host_list *list, unsigned int hash)
{
    const struct mail_vhost *vhosts;
    unsigned int count;

    vhosts = array_get(&list->vhosts, &count);
    if (count == 0)
        return NULL;

    return vhosts[hash % count].host;
}

struct mail_host *
mail_host_get_by_hash(struct mail_host_list *list, unsigned int hash)
{
    if (list->hosts_unsorted)
        mail_hosts_sort(list);

    if (list->consistent_hashing)
        return mail_host_get_by_hash_ring(list, hash);
    else
        return mail_host_get_by_hash_direct(list, hash);
}

const ARRAY_TYPE(mail_host) *mail_hosts_get(struct mail_host_list *list)
{
    if (list->hosts_unsorted)
        mail_hosts_sort(list);
    return &list->hosts;
}

struct mail_host_list *mail_hosts_init(bool consistent_hashing)
{
    struct mail_host_list *list;

    list = i_new(struct mail_host_list, 1);
    list->consistent_hashing = consistent_hashing;
    i_array_init(&list->hosts, 16);
    i_array_init(&list->vhosts, 16*VHOST_MULTIPLIER);
    return list;
}

void mail_hosts_deinit(struct mail_host_list **_list)
{
    struct mail_host_list *list = *_list;
    struct mail_host **hostp;

    *_list = NULL;

    array_foreach_modifiable(&list->hosts, hostp)
        i_free(*hostp);
    array_free(&list->hosts);
    array_free(&list->vhosts);
    i_free(list);
}

static struct mail_host *mail_host_dup(const struct mail_host *src)
{
    struct mail_host *dest;

    dest = i_new(struct mail_host, 1);
    *dest = *src;
    return dest;
}

struct mail_host_list *mail_hosts_dup(const struct mail_host_list *src)
{
    struct mail_host_list *dest;
    struct mail_host *const *hostp, *dest_host;

    dest = mail_hosts_init(src->consistent_hashing);
    array_foreach(&src->hosts, hostp) {
        dest_host = mail_host_dup(*hostp);
        array_append(&dest->hosts, &dest_host, 1);
    }
    mail_hosts_sort(dest);
    return dest;
}