diff options
Diffstat (limited to 'src/nss-resolve/nss-resolve.c')
| -rw-r--r-- | src/nss-resolve/nss-resolve.c | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/nss-resolve/nss-resolve.c b/src/nss-resolve/nss-resolve.c index 5268fb763a..b2cb19a7b4 100644 --- a/src/nss-resolve/nss-resolve.c +++ b/src/nss-resolve/nss-resolve.c @@ -29,6 +29,7 @@ #include <net/if.h> #include <stdlib.h> #include <arpa/inet.h> +#include <dlfcn.h> #include "sd-bus.h" #include "bus-util.h" @@ -43,6 +44,27 @@ NSS_GETHOSTBYADDR_PROTOTYPES(resolve); #define DNS_CALL_TIMEOUT_USEC (45*USEC_PER_SEC) +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; @@ -143,6 +165,25 @@ 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; @@ -309,6 +350,29 @@ 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; @@ -505,6 +569,29 @@ 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; |