src/passwd/nscd_query.c

   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
  10 static const struct {
  11         short sun_family;
  12         char sun_path[21];
  13 } addr = {
  14         AF_UNIX,
  15         "/var/run/nscd/socket"
  16 };
  17
  18 FILE *__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;
  38 retry:
  39         memset(buf, 0, len);
  40         buf[0] = NSCDVERSION;
  41
  42         fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
  43         if (fd < 0) return NULL;
  44
  45         if(!(f = fdopen(fd, "r"))) {
  46                 close(fd);
  47                 return 0;
  48         }
  49
  50         if (req_buf[2] > LOGIN_NAME_MAX)
  51                 return f;
  52
  53         if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
  54                 /* If there isn't a running nscd we simulate a "not found"
  55                  * result and the caller is responsible for calling
  56                  * fclose on the (unconnected) socket. The value of
  57                  * errno must be left unchanged in this case.  */
  58                 if (errno == EACCES || errno == ECONNREFUSED || errno == ENOENT) {
  59                         errno = errno_save;
  60                         return f;
  61                 }
  62                 goto error;
  63         }
  64
  65         if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 0)
  66                 goto error;
  67
  68         if (!fread(buf, len, 1, f)) {
  69                 /* If the VERSION entry mismatches nscd will disconnect. The
  70                  * most likely cause is that the endianness mismatched. So, we
  71                  * byteswap and try once more. (if we already swapped, just
  72                  * fail out)
  73                  */
  74                 if (ferror(f)) goto error;
  75                 if (!*swap) {
  76                         fclose(f);
  77                         for (i = 0; i < sizeof(req_buf)/sizeof(req_buf[0]); i++) {
  78                                 req_buf[i] = bswap_32(req_buf[i]);
  79                         }
  80                         *swap = 1;
  81                         goto retry;
  82                 } else {
  83                         errno = EIO;
  84                         goto error;
  85                 }
  86         }
  87
  88         if (*swap) {
  89                 for (i = 0; i < len/sizeof(buf[0]); i++) {
  90                         buf[i] = bswap_32(buf[i]);
  91                 }
  92         }
  93
  94         /* The first entry in every nscd response is the version number. This
  95          * really shouldn't happen, and is evidence of some form of malformed
  96          * response.
  97          */
  98         if(buf[0] != NSCDVERSION) {
  99                 errno = EIO;
 100                 goto error;
 101         }
 102
 103         return f;
 104 error:
 105         fclose(f);
 106         return 0;
 107 }