chiark / gitweb /
Update TODO
[elogind.git] / src / nss-resolve / nss-resolve.c
index 7b0c24fbeacb1dc073aa95df8ef1ae132ea86ba8..3f32ed06507df81eb72a7aa0c975b27cf5cba52e 100644 (file)
 #include <net/if.h>
 #include <stdlib.h>
 #include <arpa/inet.h>
+#include <dlfcn.h>
 
 #include "sd-bus.h"
 #include "bus-util.h"
-#include "bus-errors.h"
+#include "bus-common-errors.h"
 #include "macro.h"
 #include "nss-util.h"
 #include "util.h"
@@ -43,21 +44,49 @@ 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;
+typedef void (*voidfunc_t)(void);
+
+static voidfunc_t find_fallback(const char *module, const char *symbol) {
+        void *dl;
+
+        /* Try to find a fallback NSS module symbol */
+
+        dl = dlopen(module, RTLD_LAZY|RTLD_NODELETE);
+        if (!dl)
+                return NULL;
+
+        return dlsym(dl, symbol);
+}
+
+static bool bus_error_shall_fallback(sd_bus_error *e) {
+        return sd_bus_error_has_name(e, SD_BUS_ERROR_SERVICE_UNKNOWN) ||
+               sd_bus_error_has_name(e, SD_BUS_ERROR_NAME_HAS_NO_OWNER) ||
+               sd_bus_error_has_name(e, SD_BUS_ERROR_NO_REPLY) ||
+               sd_bus_error_has_name(e, SD_BUS_ERROR_ACCESS_DENIED);
+}
+
+static int count_addresses(sd_bus_message *m, int af, const char **canonical) {
+        int c = 0, r, ifindex;
 
         assert(m);
-        assert(ret);
+        assert(canonical);
+
+        r = sd_bus_message_read(m, "i", &ifindex);
+        if (r < 0)
+                return r;
 
-        while ((r = sd_bus_message_enter_container(m, 'r', "yayi")) > 0) {
-                unsigned char family;
+        r = sd_bus_message_enter_container(m, 'a', "(iay)");
+        if (r < 0)
+                return r;
 
-                r = sd_bus_message_read(m, "y", &family);
+        while ((r = sd_bus_message_enter_container(m, 'r', "iay")) > 0) {
+                int family;
+
+                r = sd_bus_message_read(m, "i", &family);
                 if (r < 0)
                         return r;
 
-                r = sd_bus_message_skip(m, "ayi");
+                r = sd_bus_message_skip(m, "ay");
                 if (r < 0)
                         return r;
 
@@ -73,12 +102,19 @@ static int count_addresses(sd_bus_message *m, unsigned af, unsigned *ret) {
         if (r < 0)
                 return r;
 
-        r = sd_bus_message_rewind(m, false);
+        r = sd_bus_message_exit_container(m);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_read(m, "s", canonical);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_rewind(m, true);
         if (r < 0)
                 return r;
 
-        *ret = c;
-        return 0;
+        return c;
 }
 
 enum nss_status _nss_resolve_gethostbyname4_r(
@@ -91,11 +127,11 @@ enum nss_status _nss_resolve_gethostbyname4_r(
         _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;
+        _cleanup_bus_close_unref_ sd_bus *bus = NULL;
+        const char *canonical = NULL;
         size_t l, ms, idx;
         char *r_name;
-        unsigned i = 0, c = 0;
-        int r;
+        int c, r, i = 0, ifindex;
 
         assert(name);
         assert(pat);
@@ -121,7 +157,7 @@ enum nss_status _nss_resolve_gethostbyname4_r(
         if (r < 0)
                 goto fail;
 
-        r = sd_bus_message_append(req, "sy", name, AF_UNSPEC);
+        r = sd_bus_message_append(req, "isit", 0, name, AF_UNSPEC, (uint64_t) 0);
         if (r < 0)
                 goto fail;
 
@@ -133,26 +169,45 @@ enum nss_status _nss_resolve_gethostbyname4_r(
                         return NSS_STATUS_NOTFOUND;
                 }
 
+                if (bus_error_shall_fallback(&error)) {
+
+                        enum nss_status (*fallback)(
+                                        const char *name,
+                                        struct gaih_addrtuple **pat,
+                                        char *buffer, size_t buflen,
+                                        int *errnop, int *h_errnop,
+                                        int32_t *ttlp);
+
+                        fallback = (enum nss_status (*)(const char *name,
+                                                        struct gaih_addrtuple **pat,
+                                                        char *buffer, size_t buflen,
+                                                        int *errnop, int *h_errnop,
+                                                        int32_t *ttlp))
+                                find_fallback("libnss_dns.so.2", "_nss_dns_gethostbyname4_r");
+                        if (fallback)
+                                return fallback(name, pat, buffer, buflen, errnop, h_errnop, ttlp);
+                }
+
                 *errnop = -r;
                 *h_errnop = NO_RECOVERY;
                 return NSS_STATUS_UNAVAIL;
         }
 
-        r = sd_bus_message_enter_container(reply, 'a', "(yayi)");
-        if (r < 0)
+        c = count_addresses(reply, AF_UNSPEC, &canonical);
+        if (c < 0) {
+                r = c;
                 goto fail;
-
-        r = count_addresses(reply, AF_UNSPEC, &c);
-        if (r < 0)
-                goto fail;
-
-        if (c <= 0) {
+        }
+        if (c == 0) {
                 *errnop = ESRCH;
                 *h_errnop = HOST_NOT_FOUND;
                 return NSS_STATUS_NOTFOUND;
         }
 
-        l = strlen(name);
+        if (isempty(canonical))
+                canonical = name;
+
+        l = strlen(canonical);
         ms = ALIGN(l+1) + ALIGN(sizeof(struct gaih_addrtuple)) * c;
         if (buflen < ms) {
                 *errnop = ENOMEM;
@@ -162,18 +217,31 @@ enum nss_status _nss_resolve_gethostbyname4_r(
 
         /* First, append name */
         r_name = buffer;
-        memcpy(r_name, name, l+1);
+        memcpy(r_name, canonical, 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;
+
+        r = sd_bus_message_read(reply, "i", &ifindex);
+        if (r < 0)
+                goto fail;
+
+        if (ifindex < 0) {
+                r = -EINVAL;
+                goto fail;
+        }
+
+        r = sd_bus_message_enter_container(reply, 'a', "(iay)");
+        if (r < 0)
+                goto fail;
+
+        while ((r = sd_bus_message_enter_container(reply, 'r', "iay")) > 0) {
+                int family;
                 const void *a;
-                int ifindex;
                 size_t sz;
 
-                r = sd_bus_message_read(reply, "y", &family);
+                r = sd_bus_message_read(reply, "i", &family);
                 if (r < 0)
                         goto fail;
 
@@ -181,10 +249,6 @@ enum nss_status _nss_resolve_gethostbyname4_r(
                 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;
@@ -192,12 +256,7 @@ enum nss_status _nss_resolve_gethostbyname4_r(
                 if (!IN_SET(family, AF_INET, AF_INET6))
                         continue;
 
-                if (sz != PROTO_ADDRESS_SIZE(family)) {
-                        r = -EINVAL;
-                        goto fail;
-                }
-
-                if (ifindex < 0) {
+                if (sz != FAMILY_ADDRESS_SIZE(family)) {
                         r = -EINVAL;
                         goto fail;
                 }
@@ -212,13 +271,10 @@ enum nss_status _nss_resolve_gethostbyname4_r(
                 idx += ALIGN(sizeof(struct gaih_addrtuple));
                 i++;
         }
-
-        assert(i == c);
-
-        r = sd_bus_message_exit_container(reply);
         if (r < 0)
                 goto fail;
 
+        assert(i == c);
         assert(idx == ms);
 
         if (*pat)
@@ -229,6 +285,11 @@ enum nss_status _nss_resolve_gethostbyname4_r(
         if (ttlp)
                 *ttlp = 0;
 
+        /* Explicitly reset all error variables */
+        *errnop = 0;
+        *h_errnop = NETDB_SUCCESS;
+        h_errno = 0;
+
         return NSS_STATUS_SUCCESS;
 
 fail:
@@ -249,10 +310,10 @@ enum nss_status _nss_resolve_gethostbyname3_r(
         _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;
+        _cleanup_bus_close_unref_ sd_bus *bus = NULL;
         size_t l, idx, ms, alen;
-        int r;
+        const char *canonical;
+        int c, r, i = 0, ifindex;
 
         assert(name);
         assert(result);
@@ -286,7 +347,7 @@ enum nss_status _nss_resolve_gethostbyname3_r(
         if (r < 0)
                 goto fail;
 
-        r = sd_bus_message_append(req, "sy", name, af);
+        r = sd_bus_message_append(req, "isit", 0, name, af, (uint64_t) 0);
         if (r < 0)
                 goto fail;
 
@@ -298,32 +359,52 @@ enum nss_status _nss_resolve_gethostbyname3_r(
                         return NSS_STATUS_NOTFOUND;
                 }
 
+                if (bus_error_shall_fallback(&error)) {
+
+                        enum nss_status (*fallback)(
+                                        const char *name,
+                                        int af,
+                                        struct hostent *result,
+                                        char *buffer, size_t buflen,
+                                        int *errnop, int *h_errnop,
+                                        int32_t *ttlp,
+                                        char **canonp);
+
+                        fallback =  (enum nss_status (*)(const char *name,
+                                                         int af,
+                                                         struct hostent *result,
+                                                         char *buffer, size_t buflen,
+                                                         int *errnop, int *h_errnop,
+                                                         int32_t *ttlp,
+                                                         char **canonp))
+                                find_fallback("libnss_dns.so.2", "_nss_dns_gethostbyname3_r");
+                        if (fallback)
+                                return fallback(name, af, result, buffer, buflen, errnop, h_errnop, ttlp, canonp);
+                }
+
                 *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)
+        c = count_addresses(reply, af, &canonical);
+        if (c < 0) {
+                r = c;
                 goto fail;
-
-        if (c <= 0) {
+        }
+        if (c == 0) {
                 *errnop = ESRCH;
                 *h_errnop = HOST_NOT_FOUND;
                 return NSS_STATUS_NOTFOUND;
         }
 
-        alen = PROTO_ADDRESS_SIZE(af);
-        l = strlen(name);
+        if (isempty(canonical))
+                canonical = name;
+
+        alen = FAMILY_ADDRESS_SIZE(af);
+        l = strlen(canonical);
 
-        ms = ALIGN(l+1) +
-                sizeof(char*) +
-                (c > 0 ? c : 1) * ALIGN(alen) +
-                (c > 0 ? c+1 : 2) * sizeof(char*);
+        ms = ALIGN(l+1) + c * ALIGN(alen) + (c+2) * sizeof(char*);
 
         if (buflen < ms) {
                 *errnop = ENOMEM;
@@ -333,23 +414,36 @@ enum nss_status _nss_resolve_gethostbyname3_r(
 
         /* First, append name */
         r_name = buffer;
-        memcpy(r_name, name, l+1);
+        memcpy(r_name, canonical, l+1);
         idx = ALIGN(l+1);
 
-        /* Second, create aliases array */
+        /* Second, create empty 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;
+
+        r = sd_bus_message_read(reply, "i", &ifindex);
+        if (r < 0)
+                goto fail;
+
+        if (ifindex < 0) {
+                r = -EINVAL;
+                goto fail;
+        }
+
+        r = sd_bus_message_enter_container(reply, 'a', "(iay)");
+        if (r < 0)
+                goto fail;
+
+        while ((r = sd_bus_message_enter_container(reply, 'r', "iay")) > 0) {
+                int family;
                 const void *a;
-                int ifindex;
                 size_t sz;
 
-                r = sd_bus_message_read(reply, "y", &family);
+                r = sd_bus_message_read(reply, "i", &family);
                 if (r < 0)
                         goto fail;
 
@@ -357,10 +451,6 @@ enum nss_status _nss_resolve_gethostbyname3_r(
                 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;
@@ -373,23 +463,16 @@ enum nss_status _nss_resolve_gethostbyname3_r(
                         goto fail;
                 }
 
-                if (ifindex < 0) {
-                        r = -EINVAL;
-                        goto fail;
-                }
-
                 memcpy(r_addr + i*ALIGN(alen), a, alen);
                 i++;
         }
+        if (r < 0)
+                goto fail;
 
         assert(i == c);
         idx += c * ALIGN(alen);
 
-        r = sd_bus_message_exit_container(reply);
-        if (r < 0)
-                goto fail;
-
-        /* Third, append address pointer array */
+        /* Fourth, 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);
@@ -405,6 +488,11 @@ enum nss_status _nss_resolve_gethostbyname3_r(
         result->h_length = alen;
         result->h_addr_list = (char**) r_addr_list;
 
+        /* Explicitly reset all error variables */
+        *errnop = 0;
+        *h_errnop = NETDB_SUCCESS;
+        h_errno = 0;
+
         if (ttlp)
                 *ttlp = 0;
 
@@ -430,11 +518,11 @@ enum nss_status _nss_resolve_gethostbyaddr2_r(
         _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;
+        _cleanup_bus_close_unref_ sd_bus *bus = NULL;
         unsigned c = 0, i = 0;
         size_t ms = 0, idx;
         const char *n;
-        int r;
+        int r, ifindex;
 
         assert(addr);
         assert(result);
@@ -448,7 +536,7 @@ enum nss_status _nss_resolve_gethostbyaddr2_r(
                 return NSS_STATUS_UNAVAIL;
         }
 
-        if (len != PROTO_ADDRESS_SIZE(af)) {
+        if (len != FAMILY_ADDRESS_SIZE(af)) {
                 *errnop = EINVAL;
                 *h_errnop = NO_RECOVERY;
                 return NSS_STATUS_UNAVAIL;
@@ -472,7 +560,7 @@ enum nss_status _nss_resolve_gethostbyaddr2_r(
         if (r < 0)
                 goto fail;
 
-        r = sd_bus_message_append(req, "y", af);
+        r = sd_bus_message_append(req, "ii", 0, af);
         if (r < 0)
                 goto fail;
 
@@ -480,7 +568,7 @@ enum nss_status _nss_resolve_gethostbyaddr2_r(
         if (r < 0)
                 goto fail;
 
-        r = sd_bus_message_append(req, "i", 0);
+        r = sd_bus_message_append(req, "t", (uint64_t) 0);
         if (r < 0)
                 goto fail;
 
@@ -492,11 +580,43 @@ enum nss_status _nss_resolve_gethostbyaddr2_r(
                         return NSS_STATUS_NOTFOUND;
                 }
 
+                if (bus_error_shall_fallback(&error)) {
+
+                        enum nss_status (*fallback)(
+                                        const void* addr, socklen_t len,
+                                        int af,
+                                        struct hostent *result,
+                                        char *buffer, size_t buflen,
+                                        int *errnop, int *h_errnop,
+                                        int32_t *ttlp);
+
+                        fallback = (enum nss_status (*)(
+                                        const void* addr, socklen_t len,
+                                        int af,
+                                        struct hostent *result,
+                                        char *buffer, size_t buflen,
+                                        int *errnop, int *h_errnop,
+                                        int32_t *ttlp))
+                                find_fallback("libnss_dns.so.2", "_nss_dns_gethostbyaddr2_r");
+
+                        if (fallback)
+                                return fallback(addr, len, af, result, buffer, buflen, errnop, h_errnop, ttlp);
+                }
+
                 *errnop = -r;
                 *h_errnop = NO_RECOVERY;
                 return NSS_STATUS_UNAVAIL;
         }
 
+        r = sd_bus_message_read(reply, "i", &ifindex);
+        if (r < 0)
+                goto fail;
+
+        if (ifindex < 0) {
+                r = -EINVAL;
+                goto fail;
+        }
+
         r = sd_bus_message_enter_container(reply, 'a', "s");
         if (r < 0)
                 goto fail;
@@ -560,6 +680,8 @@ enum nss_status _nss_resolve_gethostbyaddr2_r(
 
                 idx += ALIGN(l+1);
         }
+        if (r < 0)
+                goto fail;
 
         ((char**) r_aliases)[c-1] = NULL;
         assert(idx == ms);
@@ -573,6 +695,11 @@ enum nss_status _nss_resolve_gethostbyaddr2_r(
         if (ttlp)
                 *ttlp = 0;
 
+        /* Explicitly reset all error variables */
+        *errnop = 0;
+        *h_errnop = NETDB_SUCCESS;
+        h_errno = 0;
+
         return NSS_STATUS_SUCCESS;
 
 fail: