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authorJosiah Worcester <josiahw@gmail.com>2015-02-22 20:58:10 -0600
committerRich Felker <dalias@aerifal.cx>2015-02-23 01:02:14 -0500
commit34b423d2077a4c799d2089068d3bec91fb800256 (patch)
tree7b852fdc3d580b4d5dc12494812a5a5d11328f66 /src/passwd/nscd_query.c
parent0afef1aa24b784c86ae6121ca39e999824086c7c (diff)
downloadmusl-34b423d2077a4c799d2089068d3bec91fb800256.tar.gz
support alternate backends for the passwd and group dbs
when we fail to find the entry in the commonly accepted files, we query a server over a Unix domain socket on /var/run/nscd/socket. the protocol used here is compatible with glibc's nscd protocol on most systems (all that use 32-bit numbers for all the protocol fields, which appears to be everything but Alpha).
Diffstat (limited to 'src/passwd/nscd_query.c')
-rw-r--r--src/passwd/nscd_query.c100
1 files changed, 100 insertions, 0 deletions
diff --git a/src/passwd/nscd_query.c b/src/passwd/nscd_query.c
new file mode 100644
index 00000000..f8d0fc13
--- /dev/null
+++ b/src/passwd/nscd_query.c
@@ -0,0 +1,100 @@
+#include <sys/socket.h>
+#include <byteswap.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include "nscd.h"
+
+static const struct {
+ short sun_family;
+ char sun_path[21];
+} addr = {
+ AF_UNIX,
+ "/var/run/nscd/socket"
+};
+
+FILE *__nscd_query(int32_t req, const char *key, int32_t *buf, size_t len, int *swap)
+{
+ size_t i;
+ int fd;
+ FILE *f = 0;
+ int32_t req_buf[REQ_LEN] = {
+ NSCDVERSION,
+ req,
+ strlen(key)+1
+ };
+ struct msghdr msg = {
+ .msg_iov = (struct iovec[]){
+ {&req_buf, sizeof(req_buf)},
+ {(char*)key, strlen(key)+1}
+ },
+ .msg_iovlen = 2
+ };
+
+ if (strlen(key) > INT32_MAX - 1) {
+ return (FILE*)-1;
+ }
+
+ *swap = 0;
+retry:
+
+ fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
+ if (fd < 0) return NULL;
+
+ if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
+ /* If there isn't a running nscd we return -1 to indicate that
+ * that is precisely what happened
+ */
+ if (errno == EACCES || errno == ECONNREFUSED || errno == ENOENT) {
+ close(fd);
+ return (FILE *)-1;
+ }
+ goto error;
+ }
+
+ if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 0)
+ goto error;
+
+ if(!(f = fdopen(fd, "r"))) goto error;
+
+ if (!fread(buf, len, 1, f)) {
+ /* If the VERSION entry mismatches nscd will disconnect. The
+ * most likely cause is that the endianness mismatched. So, we
+ * byteswap and try once more. (if we already swapped, just
+ * fail out)
+ */
+ if (ferror(f)) goto error;
+ if (!*swap) {
+ fclose(f);
+ for (i = 0; i < sizeof(req_buf)/sizeof(req_buf[0]); i++) {
+ req_buf[i] = bswap_32(req_buf[i]);
+ }
+ *swap = 1;
+ goto retry;
+ } else {
+ errno = EIO;
+ goto error;
+ }
+ }
+
+ if (*swap) {
+ for (i = 0; i < len/sizeof(buf[0]); i++) {
+ buf[i] = bswap_32(buf[i]);
+ }
+ }
+
+ /* The first entry in every nscd response is the version number. This
+ * really shouldn't happen, and is evidence of some form of malformed
+ * response.
+ */
+ if(buf[0] != NSCDVERSION) {
+ errno = EIO;
+ goto error;
+ }
+
+ return f;
+error:
+ if (f) fclose(f); else close(fd);
+ return 0;
+}