1#include <sys/socket.h>
  2#include <byteswap.h>
  3#include <unistd.h>
  4#include <stdio.h>
  5#include <string.h>
  6#include <errno.h>
  7#include <limits.h>
  8#include "nscd.h"
  9
 10static const struct {
 11	short sun_family;
 12	char sun_path[21];
 13} addr = {
 14	AF_UNIX,
 15	"/var/run/nscd/socket"
 16};
 17
 18FILE *__nscd_query(int32_t req, const char *key, int32_t *buf, size_t len, int *swap)
 19{
 20	size_t i;
 21	int fd;
 22	FILE *f = 0;
 23	int32_t req_buf[REQ_LEN] = {
 24		NSCDVERSION,
 25		req,
 26		strnlen(key,LOGIN_NAME_MAX)+1
 27	};
 28	struct msghdr msg = {
 29		.msg_iov = (struct iovec[]){
 30			{&req_buf, sizeof(req_buf)},
 31			{(char*)key, strlen(key)+1}
 32		},
 33		.msg_iovlen = 2
 34	};
 35	int errno_save = errno;
 36
 37	*swap = 0;
 38retry:
 39	memset(buf, 0, len);
 40	buf[0] = NSCDVERSION;
 41
 42	fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
 43	if (fd < 0) {
 44		if (errno == EAFNOSUPPORT) {
 45			f = fopen("/dev/null", "re");
 46			if (f)
 47				errno = errno_save;
 48			return f;
 49		}
 50		return 0;
 51	}
 52
 53	if(!(f = fdopen(fd, "r"))) {
 54		close(fd);
 55		return 0;
 56	}
 57
 58	if (req_buf[2] > LOGIN_NAME_MAX)
 59		return f;
 60
 61	if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
 62		/* If there isn't a running nscd we simulate a "not found"
 63		 * result and the caller is responsible for calling
 64		 * fclose on the (unconnected) socket. The value of
 65		 * errno must be left unchanged in this case.  */
 66		if (errno == EACCES || errno == ECONNREFUSED || errno == ENOENT) {
 67			errno = errno_save;
 68			return f;
 69		}
 70		goto error;
 71	}
 72
 73	if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 0)
 74		goto error;
 75
 76	if (!fread(buf, len, 1, f)) {
 77		/* If the VERSION entry mismatches nscd will disconnect. The
 78		 * most likely cause is that the endianness mismatched. So, we
 79		 * byteswap and try once more. (if we already swapped, just
 80		 * fail out)
 81		 */
 82		if (ferror(f)) goto error;
 83		if (!*swap) {
 84			fclose(f);
 85			for (i = 0; i < sizeof(req_buf)/sizeof(req_buf[0]); i++) {
 86				req_buf[i] = bswap_32(req_buf[i]);
 87			}
 88			*swap = 1;
 89			goto retry;
 90		} else {
 91			errno = EIO;
 92			goto error;
 93		}
 94	}
 95
 96	if (*swap) {
 97		for (i = 0; i < len/sizeof(buf[0]); i++) {
 98			buf[i] = bswap_32(buf[i]);
 99		}
100	}
101
102	/* The first entry in every nscd response is the version number. This
103	 * really shouldn't happen, and is evidence of some form of malformed
104	 * response.
105	 */
106	if(buf[0] != NSCDVERSION) {
107		errno = EIO;
108		goto error;
109	}
110
111	return f;
112error:
113	fclose(f);
114	return 0;
115}