resolved: add small NSS module that uses resolved to resolve DNS names

1 files changed, 585 insertions, 0 deletions

diff --git a/src/nss-resolve/nss-resolve.c b/src/nss-resolve/nss-resolve.c
new file mode 100644
index 0000000000..7b0c24fbea
--- /dev/null
+++ b/src/nss-resolve/nss-resolve.c
@@ -0,0 +1,585 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <limits.h>
+#include <nss.h>
+#include <sys/types.h>
+#include <netdb.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <net/if.h>
+#include <stdlib.h>
+#include <arpa/inet.h>
+
+#include "sd-bus.h"
+#include "bus-util.h"
+#include "bus-errors.h"
+#include "macro.h"
+#include "nss-util.h"
+#include "util.h"
+#include "in-addr-util.h"
+
+NSS_GETHOSTBYNAME_PROTOTYPES(resolve);
+NSS_GETHOSTBYADDR_PROTOTYPES(resolve);
+
+#define DNS_CALL_TIMEOUT_USEC (45*USEC_PER_SEC)
+
+static int count_addresses(sd_bus_message *m, unsigned af, unsigned *ret) {
+        unsigned c = 0;
+        int r;
+
+        assert(m);
+        assert(ret);
+
+        while ((r = sd_bus_message_enter_container(m, 'r', "yayi")) > 0) {
+                unsigned char family;
+
+                r = sd_bus_message_read(m, "y", &family);
+                if (r < 0)
+                        return r;
+
+                r = sd_bus_message_skip(m, "ayi");
+                if (r < 0)
+                        return r;
+
+                r = sd_bus_message_exit_container(m);
+                if (r < 0)
+                        return r;
+
+                if (af != AF_UNSPEC && family != af)
+                        continue;
+
+                c ++;
+        }
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_rewind(m, false);
+        if (r < 0)
+                return r;
+
+        *ret = c;
+        return 0;
+}
+
+enum nss_status _nss_resolve_gethostbyname4_r(
+                const char *name,
+                struct gaih_addrtuple **pat,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp) {
+
+        _cleanup_bus_message_unref_ sd_bus_message *req = NULL, *reply = NULL;
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+        struct gaih_addrtuple *r_tuple, *r_tuple_first = NULL;
+        _cleanup_bus_unref_ sd_bus *bus = NULL;
+        size_t l, ms, idx;
+        char *r_name;
+        unsigned i = 0, c = 0;
+        int r;
+
+        assert(name);
+        assert(pat);
+        assert(buffer);
+        assert(errnop);
+        assert(h_errnop);
+
+        r = sd_bus_open_system(&bus);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_new_method_call(
+                        bus,
+                        &req,
+                        "org.freedesktop.resolve1",
+                        "/org/freedesktop/resolve1",
+                        "org.freedesktop.resolve1.Manager",
+                        "ResolveHostname");
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_set_auto_start(req, false);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_append(req, "sy", name, AF_UNSPEC);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_call(bus, req, DNS_CALL_TIMEOUT_USEC, &error, &reply);
+        if (r < 0) {
+                if (sd_bus_error_has_name(&error, _BUS_ERROR_DNS "NXDOMAIN")) {
+                        *errnop = ESRCH;
+                        *h_errnop = HOST_NOT_FOUND;
+                        return NSS_STATUS_NOTFOUND;
+                }
+
+                *errnop = -r;
+                *h_errnop = NO_RECOVERY;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        r = sd_bus_message_enter_container(reply, 'a', "(yayi)");
+        if (r < 0)
+                goto fail;
+
+        r = count_addresses(reply, AF_UNSPEC, &c);
+        if (r < 0)
+                goto fail;
+
+        if (c <= 0) {
+                *errnop = ESRCH;
+                *h_errnop = HOST_NOT_FOUND;
+                return NSS_STATUS_NOTFOUND;
+        }
+
+        l = strlen(name);
+        ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * c;
+        if (buflen < ms) {
+                *errnop = ENOMEM;
+                *h_errnop = TRY_AGAIN;
+                return NSS_STATUS_TRYAGAIN;
+        }
+
+        /* First, append name */
+        r_name = buffer;
+        memcpy(r_name, name, l+1);
+        idx = ALIGN(l+1);
+
+        /* Second, append addresses */
+        r_tuple_first = (struct gaih_addrtuple*) (buffer + idx);
+        while ((r = sd_bus_message_enter_container(reply, 'r', "yayi")) > 0) {
+                unsigned char family;
+                const void *a;
+                int ifindex;
+                size_t sz;
+
+                r = sd_bus_message_read(reply, "y", &family);
+                if (r < 0)
+                        goto fail;
+
+                r = sd_bus_message_read_array(reply, 'y', &a, &sz);
+                if (r < 0)
+                        goto fail;
+
+                r = sd_bus_message_read(reply, "i", &ifindex);
+                if (r < 0)
+                        goto fail;
+
+                r = sd_bus_message_exit_container(reply);
+                if (r < 0)
+                        goto fail;
+
+                if (!IN_SET(family, AF_INET, AF_INET6))
+                        continue;
+
+                if (sz != PROTO_ADDRESS_SIZE(family)) {
+                        r = -EINVAL;
+                        goto fail;
+                }
+
+                if (ifindex < 0) {
+                        r = -EINVAL;
+                        goto fail;
+                }
+
+                r_tuple = (struct gaih_addrtuple*) (buffer + idx);
+                r_tuple->next = i == c-1 ? NULL : (struct gaih_addrtuple*) ((char*) r_tuple + ALIGN(sizeof(struct gaih_addrtuple)));
+                r_tuple->name = r_name;
+                r_tuple->family = family;
+                r_tuple->scopeid = ifindex;
+                memcpy(r_tuple->addr, a, sz);
+
+                idx += ALIGN(sizeof(struct gaih_addrtuple));
+                i++;
+        }
+
+        assert(i == c);
+
+        r = sd_bus_message_exit_container(reply);
+        if (r < 0)
+                goto fail;
+
+        assert(idx == ms);
+
+        if (*pat)
+                **pat = *r_tuple_first;
+        else
+                *pat = r_tuple_first;
+
+        if (ttlp)
+                *ttlp = 0;
+
+        return NSS_STATUS_SUCCESS;
+
+fail:
+        *errnop = -r;
+        *h_errnop = NO_DATA;
+        return NSS_STATUS_UNAVAIL;
+}
+
+enum nss_status _nss_resolve_gethostbyname3_r(
+                const char *name,
+                int af,
+                struct hostent *result,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp,
+                char **canonp) {
+
+        _cleanup_bus_message_unref_ sd_bus_message *req = NULL, *reply = NULL;
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+        char *r_name, *r_aliases, *r_addr, *r_addr_list;
+        _cleanup_bus_unref_ sd_bus *bus = NULL;
+        unsigned c = 0, i = 0;
+        size_t l, idx, ms, alen;
+        int r;
+
+        assert(name);
+        assert(result);
+        assert(buffer);
+        assert(errnop);
+        assert(h_errnop);
+
+        if (af == AF_UNSPEC)
+                af = AF_INET;
+
+        if (af != AF_INET && af != AF_INET6) {
+                r = -EAFNOSUPPORT;
+                goto fail;
+        }
+
+        r = sd_bus_open_system(&bus);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_new_method_call(
+                        bus,
+                        &req,
+                        "org.freedesktop.resolve1",
+                        "/org/freedesktop/resolve1",
+                        "org.freedesktop.resolve1.Manager",
+                        "ResolveHostname");
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_set_auto_start(req, false);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_append(req, "sy", name, af);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_call(bus, req, DNS_CALL_TIMEOUT_USEC, &error, &reply);
+        if (r < 0) {
+                if (sd_bus_error_has_name(&error, _BUS_ERROR_DNS "NXDOMAIN")) {
+                        *errnop = ESRCH;
+                        *h_errnop = HOST_NOT_FOUND;
+                        return NSS_STATUS_NOTFOUND;
+                }
+
+                *errnop = -r;
+                *h_errnop = NO_RECOVERY;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        r = sd_bus_message_enter_container(reply, 'a', "(yayi)");
+        if (r < 0)
+                goto fail;
+
+        r = count_addresses(reply, af, &c);
+        if (r < 0)
+                goto fail;
+
+        if (c <= 0) {
+                *errnop = ESRCH;
+                *h_errnop = HOST_NOT_FOUND;
+                return NSS_STATUS_NOTFOUND;
+        }
+
+        alen = PROTO_ADDRESS_SIZE(af);
+        l = strlen(name);
+
+        ms = ALIGN(l+1) +
+                sizeof(char*) +
+                (c > 0 ? c : 1) * ALIGN(alen) +
+                (c > 0 ? c+1 : 2) * sizeof(char*);
+
+        if (buflen < ms) {
+                *errnop = ENOMEM;
+                *h_errnop = TRY_AGAIN;
+                return NSS_STATUS_TRYAGAIN;
+        }
+
+        /* First, append name */
+        r_name = buffer;
+        memcpy(r_name, name, l+1);
+        idx = ALIGN(l+1);
+
+        /* Second, create aliases array */
+        r_aliases = buffer + idx;
+        ((char**) r_aliases)[0] = NULL;
+        idx += sizeof(char*);
+
+        /* Third, append addresses */
+        r_addr = buffer + idx;
+        while ((r = sd_bus_message_enter_container(reply, 'r', "yayi")) > 0) {
+                unsigned char family;
+                const void *a;
+                int ifindex;
+                size_t sz;
+
+                r = sd_bus_message_read(reply, "y", &family);
+                if (r < 0)
+                        goto fail;
+
+                r = sd_bus_message_read_array(reply, 'y', &a, &sz);
+                if (r < 0)
+                        goto fail;
+
+                r = sd_bus_message_read(reply, "i", &ifindex);
+                if (r < 0)
+                        goto fail;
+
+                r = sd_bus_message_exit_container(reply);
+                if (r < 0)
+                        goto fail;
+
+                if (family != af)
+                        continue;
+
+                if (sz != alen) {
+                        r = -EINVAL;
+                        goto fail;
+                }
+
+                if (ifindex < 0) {
+                        r = -EINVAL;
+                        goto fail;
+                }
+
+                memcpy(r_addr + i*ALIGN(alen), a, alen);
+                i++;
+        }
+
+        assert(i == c);
+        idx += c * ALIGN(alen);
+
+        r = sd_bus_message_exit_container(reply);
+        if (r < 0)
+                goto fail;
+
+        /* Third, append address pointer array */
+        r_addr_list = buffer + idx;
+        for (i = 0; i < c; i++)
+                ((char**) r_addr_list)[i] = r_addr + i*ALIGN(alen);
+
+        ((char**) r_addr_list)[i] = NULL;
+        idx += (c+1) * sizeof(char*);
+
+        assert(idx == ms);
+
+        result->h_name = r_name;
+        result->h_aliases = (char**) r_aliases;
+        result->h_addrtype = af;
+        result->h_length = alen;
+        result->h_addr_list = (char**) r_addr_list;
+
+        if (ttlp)
+                *ttlp = 0;
+
+        if (canonp)
+                *canonp = r_name;
+
+        return NSS_STATUS_SUCCESS;
+
+fail:
+        *errnop = -r;
+        *h_errnop = NO_DATA;
+        return NSS_STATUS_UNAVAIL;
+}
+
+enum nss_status _nss_resolve_gethostbyaddr2_r(
+                const void* addr, socklen_t len,
+                int af,
+                struct hostent *result,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp) {
+
+        _cleanup_bus_message_unref_ sd_bus_message *req = NULL, *reply = NULL;
+        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
+        char *r_name, *r_aliases, *r_addr, *r_addr_list;
+        _cleanup_bus_unref_ sd_bus *bus = NULL;
+        unsigned c = 0, i = 0;
+        size_t ms = 0, idx;
+        const char *n;
+        int r;
+
+        assert(addr);
+        assert(result);
+        assert(buffer);
+        assert(errnop);
+        assert(h_errnop);
+
+        if (!IN_SET(af, AF_INET, AF_INET6)) {
+                *errnop = EAFNOSUPPORT;
+                *h_errnop = NO_DATA;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        if (len != PROTO_ADDRESS_SIZE(af)) {
+                *errnop = EINVAL;
+                *h_errnop = NO_RECOVERY;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        r = sd_bus_open_system(&bus);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_new_method_call(
+                        bus,
+                        &req,
+                        "org.freedesktop.resolve1",
+                        "/org/freedesktop/resolve1",
+                        "org.freedesktop.resolve1.Manager",
+                        "ResolveAddress");
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_set_auto_start(req, false);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_append(req, "y", af);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_append_array(req, 'y', addr, len);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_append(req, "i", 0);
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_call(bus, req, DNS_CALL_TIMEOUT_USEC, &error, &reply);
+        if (r < 0) {
+                if (sd_bus_error_has_name(&error, _BUS_ERROR_DNS "NXDOMAIN")) {
+                        *errnop = ESRCH;
+                        *h_errnop = HOST_NOT_FOUND;
+                        return NSS_STATUS_NOTFOUND;
+                }
+
+                *errnop = -r;
+                *h_errnop = NO_RECOVERY;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        r = sd_bus_message_enter_container(reply, 'a', "s");
+        if (r < 0)
+                goto fail;
+
+        while ((r = sd_bus_message_read(reply, "s", &n)) > 0) {
+                c++;
+                ms += ALIGN(strlen(n) + 1);
+        }
+        if (r < 0)
+                goto fail;
+
+        r = sd_bus_message_rewind(reply, false);
+        if (r < 0)
+                return r;
+
+        if (c <= 0) {
+                *errnop = ESRCH;
+                *h_errnop = HOST_NOT_FOUND;
+                return NSS_STATUS_NOTFOUND;
+        }
+
+        ms += ALIGN(len) +              /* the address */
+              2 * sizeof(char*) +       /* pointers to the address, plus trailing NULL */
+              c * sizeof(char*);        /* pointers to aliases, plus trailing NULL */
+
+        if (buflen < ms) {
+                *errnop = ENOMEM;
+                *h_errnop = TRY_AGAIN;
+                return NSS_STATUS_TRYAGAIN;
+        }
+
+        /* First, place address */
+        r_addr = buffer;
+        memcpy(r_addr, addr, len);
+        idx = ALIGN(len);
+
+        /* Second, place address list */
+        r_addr_list = buffer + idx;
+        ((char**) r_addr_list)[0] = r_addr;
+        ((char**) r_addr_list)[1] = NULL;
+        idx += sizeof(char*) * 2;
+
+        /* Third, reserve space for the aliases array */
+        r_aliases = buffer + idx;
+        idx += sizeof(char*) * c;
+
+        /* Fourth, place aliases */
+        i = 0;
+        r_name = buffer + idx;
+        while ((r = sd_bus_message_read(reply, "s", &n)) > 0) {
+                char *p;
+                size_t l;
+
+                l = strlen(n);
+                p = buffer + idx;
+                memcpy(p, n, l+1);
+
+                if (i > 1)
+                        ((char**) r_aliases)[i-1] = p;
+                i++;
+
+                idx += ALIGN(l+1);
+        }
+
+        ((char**) r_aliases)[c-1] = NULL;
+        assert(idx == ms);
+
+        result->h_name = r_name;
+        result->h_aliases = (char**) r_aliases;
+        result->h_addrtype = af;
+        result->h_length = len;
+        result->h_addr_list = (char**) r_addr_list;
+
+        if (ttlp)
+                *ttlp = 0;
+
+        return NSS_STATUS_SUCCESS;
+
+fail:
+        *errnop = -r;
+        *h_errnop = NO_DATA;
+        return NSS_STATUS_UNAVAIL;
+}
+
+NSS_GETHOSTBYNAME_FALLBACKS(resolve);
+NSS_GETHOSTBYADDR_FALLBACKS(resolve);