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 "nscd.h"
   8
   9 static const struct {
  10         short sun_family;
  11         char sun_path[21];
  12 } addr = {
  13         AF_UNIX,
  14         "/var/run/nscd/socket"
  15 };
  16
  17 FILE *__nscd_query(int32_t req, const char *key, int32_t *buf, size_t len, int *swap)
  18 {
  19         size_t i;
  20         int fd;
  21         FILE *f = 0;
  22         int32_t req_buf[REQ_LEN] = {
  23                 NSCDVERSION,
  24                 req,
  25                 strlen(key)+1
  26         };
  27         struct msghdr msg = {
  28                 .msg_iov = (struct iovec[]){
  29                         {&req_buf, sizeof(req_buf)},
  30                         {(char*)key, strlen(key)+1}
  31                 },
  32                 .msg_iovlen = 2
  33         };
  34
  35         *swap = 0;
  36 retry:
  37         memset(buf, 0, len);
  38         buf[0] = NSCDVERSION;
  39
  40         fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
  41         if (fd < 0) return NULL;
  42
  43         if(!(f = fdopen(fd, "r"))) {
  44                 close(fd);
  45                 return 0;
  46         }
  47
  48         if (strlen(key) > INT32_MAX - 1)
  49                 return f;
  50
  51         if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
  52                 /* If there isn't a running nscd we return -1 to indicate that
  53                  * that is precisely what happened
  54                  */
  55                 if (errno == EACCES || errno == ECONNREFUSED || errno == ENOENT)
  56                         return f;
  57                 goto error;
  58         }
  59
  60         if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 0)
  61                 goto error;
  62
  63         if (!fread(buf, len, 1, f)) {
  64                 /* If the VERSION entry mismatches nscd will disconnect. The
  65                  * most likely cause is that the endianness mismatched. So, we
  66                  * byteswap and try once more. (if we already swapped, just
  67                  * fail out)
  68                  */
  69                 if (ferror(f)) goto error;
  70                 if (!*swap) {
  71                         fclose(f);
  72                         for (i = 0; i < sizeof(req_buf)/sizeof(req_buf[0]); i++) {
  73                                 req_buf[i] = bswap_32(req_buf[i]);
  74                         }
  75                         *swap = 1;
  76                         goto retry;
  77                 } else {
  78                         errno = EIO;
  79                         goto error;
  80                 }
  81         }
  82
  83         if (*swap) {
  84                 for (i = 0; i < len/sizeof(buf[0]); i++) {
  85                         buf[i] = bswap_32(buf[i]);
  86                 }
  87         }
  88
  89         /* The first entry in every nscd response is the version number. This
  90          * really shouldn't happen, and is evidence of some form of malformed
  91          * response.
  92          */
  93         if(buf[0] != NSCDVERSION) {
  94                 errno = EIO;
  95                 goto error;
  96         }
  97
  98         return f;
  99 error:
 100         fclose(f);
 101         return 0;
 102 }