Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 501 insertions, 0 deletions

diff --git a/src/nss-myhostname/nss-myhostname.c b/src/nss-myhostname/nss-myhostname.c
new file mode 100644
index 0000000..e491351
--- /dev/null
+++ b/src/nss-myhostname/nss-myhostname.c
@@ -0,0 +1,501 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <net/if.h>
+#include <netdb.h>
+#include <nss.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "alloc-util.h"
+#include "hostname-util.h"
+#include "local-addresses.h"
+#include "macro.h"
+#include "nss-util.h"
+#include "signal-util.h"
+#include "string-util.h"
+#include "util.h"
+
+/* We use 127.0.0.2 as IPv4 address. This has the advantage over
+ * 127.0.0.1 that it can be translated back to the local hostname. For
+ * IPv6 we use ::1 which unfortunately will not translate back to the
+ * hostname but instead something like "localhost" or so. */
+
+#define LOCALADDRESS_IPV4 (htobe32(0x7F000002))
+#define LOCALADDRESS_IPV6 &in6addr_loopback
+
+NSS_GETHOSTBYNAME_PROTOTYPES(myhostname);
+NSS_GETHOSTBYADDR_PROTOTYPES(myhostname);
+
+enum nss_status _nss_myhostname_gethostbyname4_r(
+                const char *name,
+                struct gaih_addrtuple **pat,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp) {
+
+        struct gaih_addrtuple *r_tuple, *r_tuple_prev = NULL;
+        _cleanup_free_ struct local_address *addresses = NULL;
+        _cleanup_free_ char *hn = NULL;
+        const char *canonical = NULL;
+        int n_addresses = 0;
+        uint32_t local_address_ipv4;
+        struct local_address *a;
+        size_t l, idx, ms;
+        char *r_name;
+        unsigned n;
+
+        PROTECT_ERRNO;
+        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+        assert(name);
+        assert(pat);
+        assert(buffer);
+        assert(errnop);
+        assert(h_errnop);
+
+        if (is_localhost(name)) {
+                /* We respond to 'localhost', so that /etc/hosts
+                 * is optional */
+
+                canonical = "localhost";
+                local_address_ipv4 = htobe32(INADDR_LOOPBACK);
+
+        } else if (is_gateway_hostname(name)) {
+
+                n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
+                if (n_addresses <= 0) {
+                        *h_errnop = HOST_NOT_FOUND;
+                        return NSS_STATUS_NOTFOUND;
+                }
+
+                canonical = "_gateway";
+
+        } else {
+                hn = gethostname_malloc();
+                if (!hn) {
+                        UNPROTECT_ERRNO;
+                        *errnop = ENOMEM;
+                        *h_errnop = NO_RECOVERY;
+                        return NSS_STATUS_TRYAGAIN;
+                }
+
+                /* We respond to our local host name, our hostname suffixed with a single dot. */
+                if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
+                        *h_errnop = HOST_NOT_FOUND;
+                        return NSS_STATUS_NOTFOUND;
+                }
+
+                n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
+                if (n_addresses < 0)
+                        n_addresses = 0;
+
+                canonical = hn;
+                local_address_ipv4 = LOCALADDRESS_IPV4;
+        }
+
+        l = strlen(canonical);
+        ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * (n_addresses > 0 ? n_addresses : 2);
+        if (buflen < ms) {
+                UNPROTECT_ERRNO;
+                *errnop = ERANGE;
+                *h_errnop = NETDB_INTERNAL;
+                return NSS_STATUS_TRYAGAIN;
+        }
+
+        /* First, fill in hostname */
+        r_name = buffer;
+        memcpy(r_name, canonical, l+1);
+        idx = ALIGN(l+1);
+
+        assert(n_addresses >= 0);
+        if (n_addresses == 0) {
+                /* Second, fill in IPv6 tuple */
+                r_tuple = (struct gaih_addrtuple*) (buffer + idx);
+                r_tuple->next = r_tuple_prev;
+                r_tuple->name = r_name;
+                r_tuple->family = AF_INET6;
+                memcpy(r_tuple->addr, LOCALADDRESS_IPV6, 16);
+                r_tuple->scopeid = 0;
+
+                idx += ALIGN(sizeof(struct gaih_addrtuple));
+                r_tuple_prev = r_tuple;
+
+                /* Third, fill in IPv4 tuple */
+                r_tuple = (struct gaih_addrtuple*) (buffer + idx);
+                r_tuple->next = r_tuple_prev;
+                r_tuple->name = r_name;
+                r_tuple->family = AF_INET;
+                *(uint32_t*) r_tuple->addr = local_address_ipv4;
+                r_tuple->scopeid = 0;
+
+                idx += ALIGN(sizeof(struct gaih_addrtuple));
+                r_tuple_prev = r_tuple;
+        }
+
+        /* Fourth, fill actual addresses in, but in backwards order */
+        for (a = addresses + n_addresses - 1, n = 0; (int) n < n_addresses; n++, a--) {
+                r_tuple = (struct gaih_addrtuple*) (buffer + idx);
+                r_tuple->next = r_tuple_prev;
+                r_tuple->name = r_name;
+                r_tuple->family = a->family;
+                r_tuple->scopeid = a->family == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&a->address.in6) ? a->ifindex : 0;
+                memcpy(r_tuple->addr, &a->address, 16);
+
+                idx += ALIGN(sizeof(struct gaih_addrtuple));
+                r_tuple_prev = r_tuple;
+        }
+
+        /* Verify the size matches */
+        assert(idx == ms);
+
+        /* Nscd expects us to store the first record in **pat. */
+        if (*pat)
+                **pat = *r_tuple_prev;
+        else
+                *pat = r_tuple_prev;
+
+        if (ttlp)
+                *ttlp = 0;
+
+        /* Explicitly reset both *h_errnop and h_errno to work around
+         * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
+        *h_errnop = NETDB_SUCCESS;
+        h_errno = 0;
+
+        return NSS_STATUS_SUCCESS;
+}
+
+static enum nss_status fill_in_hostent(
+                const char *canonical, const char *additional,
+                int af,
+                struct local_address *addresses, unsigned n_addresses,
+                uint32_t local_address_ipv4,
+                struct hostent *result,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp,
+                char **canonp) {
+
+        size_t l_canonical, l_additional, idx, ms, alen;
+        char *r_addr, *r_name, *r_aliases, *r_alias = NULL, *r_addr_list;
+        struct local_address *a;
+        unsigned n, c;
+
+        assert(canonical);
+        assert(result);
+        assert(buffer);
+        assert(errnop);
+        assert(h_errnop);
+
+        PROTECT_ERRNO;
+
+        alen = FAMILY_ADDRESS_SIZE(af);
+
+        for (a = addresses, n = 0, c = 0; n < n_addresses; a++, n++)
+                if (af == a->family)
+                        c++;
+
+        l_canonical = strlen(canonical);
+        l_additional = strlen_ptr(additional);
+        ms = ALIGN(l_canonical+1)+
+                (additional ? ALIGN(l_additional+1) : 0) +
+                sizeof(char*) +
+                (additional ? sizeof(char*) : 0) +
+                (c > 0 ? c : 1) * ALIGN(alen) +
+                (c > 0 ? c+1 : 2) * sizeof(char*);
+
+        if (buflen < ms) {
+                UNPROTECT_ERRNO;
+                *errnop = ERANGE;
+                *h_errnop = NETDB_INTERNAL;
+                return NSS_STATUS_TRYAGAIN;
+        }
+
+        /* First, fill in hostnames */
+        r_name = buffer;
+        memcpy(r_name, canonical, l_canonical+1);
+        idx = ALIGN(l_canonical+1);
+
+        if (additional) {
+                r_alias = buffer + idx;
+                memcpy(r_alias, additional, l_additional+1);
+                idx += ALIGN(l_additional+1);
+        }
+
+        /* Second, create aliases array */
+        r_aliases = buffer + idx;
+        if (additional) {
+                ((char**) r_aliases)[0] = r_alias;
+                ((char**) r_aliases)[1] = NULL;
+                idx += 2*sizeof(char*);
+        } else {
+                ((char**) r_aliases)[0] = NULL;
+                idx += sizeof(char*);
+        }
+
+        /* Third, add addresses */
+        r_addr = buffer + idx;
+        if (c > 0) {
+                unsigned i = 0;
+
+                for (a = addresses, n = 0; n < n_addresses; a++, n++) {
+                        if (af != a->family)
+                                continue;
+
+                        memcpy(r_addr + i*ALIGN(alen), &a->address, alen);
+                        i++;
+                }
+
+                assert(i == c);
+                idx += c*ALIGN(alen);
+        } else {
+                if (af == AF_INET)
+                        *(uint32_t*) r_addr = local_address_ipv4;
+                else
+                        memcpy(r_addr, LOCALADDRESS_IPV6, 16);
+
+                idx += ALIGN(alen);
+        }
+
+        /* Fourth, add address pointer array */
+        r_addr_list = buffer + idx;
+        if (c > 0) {
+                unsigned i;
+
+                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*);
+
+        } else {
+                ((char**) r_addr_list)[0] = r_addr;
+                ((char**) r_addr_list)[1] = NULL;
+                idx += 2 * sizeof(char*);
+        }
+
+        /* Verify the size matches */
+        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;
+
+        /* Explicitly reset both *h_errnop and h_errno to work around
+         * https://bugzilla.redhat.com/show_bug.cgi?id=1125975 */
+        *h_errnop = NETDB_SUCCESS;
+        h_errno = 0;
+
+        return NSS_STATUS_SUCCESS;
+}
+
+enum nss_status _nss_myhostname_gethostbyname3_r(
+                const char *name,
+                int af,
+                struct hostent *host,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp,
+                char **canonp) {
+
+        _cleanup_free_ struct local_address *addresses = NULL;
+        const char *canonical, *additional = NULL;
+        _cleanup_free_ char *hn = NULL;
+        uint32_t local_address_ipv4 = 0;
+        int n_addresses = 0;
+
+        PROTECT_ERRNO;
+        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+        assert(name);
+        assert(host);
+        assert(buffer);
+        assert(errnop);
+        assert(h_errnop);
+
+        if (af == AF_UNSPEC)
+                af = AF_INET;
+
+        if (!IN_SET(af, AF_INET, AF_INET6)) {
+                UNPROTECT_ERRNO;
+                *errnop = EAFNOSUPPORT;
+                *h_errnop = NO_DATA;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        if (is_localhost(name)) {
+                canonical = "localhost";
+                local_address_ipv4 = htobe32(INADDR_LOOPBACK);
+
+        } else if (is_gateway_hostname(name)) {
+
+                n_addresses = local_gateways(NULL, 0, af, &addresses);
+                if (n_addresses <= 0) {
+                        *h_errnop = HOST_NOT_FOUND;
+                        return NSS_STATUS_NOTFOUND;
+                }
+
+                canonical = "_gateway";
+
+        } else {
+                hn = gethostname_malloc();
+                if (!hn) {
+                        UNPROTECT_ERRNO;
+                        *errnop = ENOMEM;
+                        *h_errnop = NO_RECOVERY;
+                        return NSS_STATUS_TRYAGAIN;
+                }
+
+                if (!streq(name, hn) && !streq_ptr(startswith(name, hn), ".")) {
+                        *h_errnop = HOST_NOT_FOUND;
+                        return NSS_STATUS_NOTFOUND;
+                }
+
+                n_addresses = local_addresses(NULL, 0, af, &addresses);
+                if (n_addresses < 0)
+                        n_addresses = 0;
+
+                canonical = hn;
+                additional = n_addresses <= 0 && af == AF_INET6 ? "localhost" : NULL;
+                local_address_ipv4 = LOCALADDRESS_IPV4;
+        }
+
+        UNPROTECT_ERRNO;
+
+        return fill_in_hostent(
+                        canonical, additional,
+                        af,
+                        addresses, n_addresses,
+                        local_address_ipv4,
+                        host,
+                        buffer, buflen,
+                        errnop, h_errnop,
+                        ttlp,
+                        canonp);
+}
+
+enum nss_status _nss_myhostname_gethostbyaddr2_r(
+                const void* addr, socklen_t len,
+                int af,
+                struct hostent *host,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp) {
+
+        const char *canonical = NULL, *additional = NULL;
+        uint32_t local_address_ipv4 = LOCALADDRESS_IPV4;
+        _cleanup_free_ struct local_address *addresses = NULL;
+        _cleanup_free_ char *hn = NULL;
+        int n_addresses = 0;
+        struct local_address *a;
+        bool additional_from_hostname = false;
+        unsigned n;
+
+        PROTECT_ERRNO;
+        BLOCK_SIGNALS(NSS_SIGNALS_BLOCK);
+
+        assert(addr);
+        assert(host);
+        assert(buffer);
+        assert(errnop);
+        assert(h_errnop);
+
+        if (!IN_SET(af, AF_INET, AF_INET6)) {
+                UNPROTECT_ERRNO;
+                *errnop = EAFNOSUPPORT;
+                *h_errnop = NO_DATA;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        if (len != FAMILY_ADDRESS_SIZE(af)) {
+                UNPROTECT_ERRNO;
+                *errnop = EINVAL;
+                *h_errnop = NO_RECOVERY;
+                return NSS_STATUS_UNAVAIL;
+        }
+
+        if (af == AF_INET) {
+                if ((*(uint32_t*) addr) == LOCALADDRESS_IPV4)
+                        goto found;
+
+                if ((*(uint32_t*) addr) == htobe32(INADDR_LOOPBACK)) {
+                        canonical = "localhost";
+                        local_address_ipv4 = htobe32(INADDR_LOOPBACK);
+                        goto found;
+                }
+
+        } else {
+                assert(af == AF_INET6);
+
+                if (memcmp(addr, LOCALADDRESS_IPV6, 16) == 0) {
+                        canonical = "localhost";
+                        additional_from_hostname = true;
+                        goto found;
+                }
+        }
+
+        n_addresses = local_addresses(NULL, 0, AF_UNSPEC, &addresses);
+        for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
+                if (af != a->family)
+                        continue;
+
+                if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0)
+                        goto found;
+        }
+
+        addresses = mfree(addresses);
+
+        n_addresses = local_gateways(NULL, 0, AF_UNSPEC, &addresses);
+        for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
+                if (af != a->family)
+                        continue;
+
+                if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) {
+                        canonical = "_gateway";
+                        goto found;
+                }
+        }
+
+        *h_errnop = HOST_NOT_FOUND;
+        return NSS_STATUS_NOTFOUND;
+
+found:
+        if (!canonical || additional_from_hostname) {
+                hn = gethostname_malloc();
+                if (!hn) {
+                        UNPROTECT_ERRNO;
+                        *errnop = ENOMEM;
+                        *h_errnop = NO_RECOVERY;
+                        return NSS_STATUS_TRYAGAIN;
+                }
+
+                if (!canonical)
+                        canonical = hn;
+                else
+                        additional = hn;
+        }
+
+        UNPROTECT_ERRNO;
+        return fill_in_hostent(
+                        canonical, additional,
+                        af,
+                        addresses, n_addresses,
+                        local_address_ipv4,
+                        host,
+                        buffer, buflen,
+                        errnop, h_errnop,
+                        ttlp,
+                        NULL);
+}
+
+NSS_GETHOSTBYNAME_FALLBACKS(myhostname);
+NSS_GETHOSTBYADDR_FALLBACKS(myhostname);