nss-icmp.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <unistd.h>
   4 #include <string.h>
   5 #include <errno.h>
   6 #include <sys/socket.h>
   7 #include <netinet/in.h>
   8 #include <netdb.h>
   9 #include <arpa/inet.h>
  10 #include <nss.h>
  11 #include <sys/types.h>
  12 #include <fcntl.h>
  13
  14 #define CONFIGFILE "/etc/nss-icmp.conf"
  15
  16 struct cache {
  17     struct cache *next, *prev;
  18     char *addr;
  19     socklen_t addrlen;
  20     int af;
  21     int notfound;
  22     char **names;
  23 };
  24
  25 static int inited = 0;
  26 static int timeout = -1;
  27 static int usecache = 1;
  28 static struct cache *cache = NULL;
  29
  30 static void readconfig(void)
  31 {
  32     FILE *f;
  33     char linebuf[1024];
  34     char *p, *p2;
  35
  36     if((f = fopen(CONFIGFILE, "r")) == NULL)
  37         return;
  38
  39     while(fgets(linebuf, sizeof(linebuf), f) != NULL) {
  40         if(linebuf[0] == '#')
  41             continue;
  42         if((p = strchr(linebuf, '\n')) != NULL)
  43             *p = 0;
  44         if((p = strchr(linebuf, ' ')) != NULL) {
  45             p2 = p + 1;
  46             *p = 0;
  47         }
  48         if(!strcmp(linebuf, "timeout")) {
  49             if(p2 == NULL)
  50                 continue;
  51             timeout = atoi(p2);
  52         }
  53         if(!strcmp(linebuf, "nocache")) {
  54             usecache = 0;
  55         }
  56     }
  57
  58     fclose(f);
  59 }
  60
  61 static void freecache(struct cache *cc)
  62 {
  63     int i;
  64
  65     if(cc->next != NULL)
  66         cc->next->prev = cc->prev;
  67     if(cc->prev != NULL)
  68         cc->prev->next = cc->next;
  69     if(cc == cache)
  70         cache = cc->next;
  71     if(cc->addr != NULL)
  72         free(cc->addr);
  73     if(cc->names != NULL) {
  74         for(i = 0; cc->names[i] != NULL; i++)
  75             free(cc->names[i]);
  76         free(cc->names);
  77     }
  78     free(cc);
  79 }
  80
  81 static void cachenotfound(const void *addr, socklen_t len, int af)
  82 {
  83     struct cache *cc;
  84
  85     for(cc = cache; cc != NULL; cc = cc->next) {
  86         if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len))
  87             break;
  88     }
  89     if(cc == NULL) {
  90         if((cc = malloc(sizeof(*cc))) == NULL)
  91             return;
  92         memset(cc, 0, sizeof(*cc));
  93         if((cc->addr = malloc(len)) == NULL) {
  94             freecache(cc);
  95             return;
  96         }
  97         memcpy(cc->addr, addr, len);
  98         cc->addrlen = len;
  99         cc->af = af;
 100
 101         cc->notfound = 1;
 102
 103         cc->next = cache;
 104         if(cache != NULL)
 105             cache->prev = cc;
 106         cache = cc;
 107     }
 108 }
 109
 110 static void updatecache(struct hostent *he)
 111 {
 112     int i;
 113     struct cache *cc;
 114
 115     for(cc = cache; cc != NULL; cc = cc->next) {
 116         if((cc->af == he->h_addrtype) && (cc->addrlen == he->h_length) && !memcmp(cc->addr, he->h_addr_list[0], he->h_length))
 117             break;
 118     }
 119     if(cc == NULL) {
 120         if((cc = malloc(sizeof(*cc))) == NULL)
 121             return;
 122         memset(cc, 0, sizeof(*cc));
 123         if((cc->addr = malloc(he->h_length)) == NULL) {
 124             freecache(cc);
 125             return;
 126         }
 127         memcpy(cc->addr, he->h_addr_list[0], he->h_length);
 128         cc->addrlen = he->h_length;
 129         cc->af = he->h_addrtype;
 130
 131         for(i = 0; he->h_aliases[i] != NULL; i++);
 132         if((cc->names = malloc(sizeof(*(cc->names)) * (i + 1))) == NULL) {
 133             freecache(cc);
 134             return;
 135         }
 136         memset(cc->names, 0, sizeof(*(cc->names)) * (i + 1));
 137         for(i = 0; he->h_aliases[i] != NULL; i++) {
 138             if((cc->names[i] = malloc(strlen(he->h_aliases[i]) + 1)) == NULL) {
 139                 freecache(cc);
 140                 return;
 141             }
 142             strcpy(cc->names[i], he->h_aliases[i]);
 143         }
 144
 145         cc->next = cache;
 146         if(cache != NULL)
 147             cache->prev = cc;
 148         cache = cc;
 149     }
 150 }
 151
 152 enum nss_status _nss_icmp_gethostbyaddr_r(const void *addr, socklen_t len, int af, struct hostent *result, char *buffer, size_t buflen, int *errnop, int *h_errnop)
 153 {
 154     int i, ret;
 155     struct retstruct {
 156         char *aliaslist[16];
 157         char *addrlist[2];
 158         char retaddr[16];
 159     } *retbuf;
 160     char addrbuf[1024];
 161     int an, thislen;
 162     char *p, *p2, *p3;
 163     u_int8_t *ap;
 164     pid_t child;
 165     int pfd[2];
 166     int rl;
 167     struct cache *cc;
 168
 169     if(!inited) {
 170         readconfig();
 171         inited = 1;
 172     }
 173
 174     retbuf = (struct retstruct *)buffer;
 175     if((buflen < sizeof(*retbuf)) || (len > sizeof(retbuf->retaddr))) {
 176         *errnop = ENOMEM;
 177         *h_errnop = NETDB_INTERNAL;
 178         return(NSS_STATUS_UNAVAIL);
 179     }
 180
 181     for(cc = cache; cc != NULL; cc = cc->next) {
 182         if((cc->af == af) && (cc->addrlen == len) && !memcmp(cc->addr, addr, len))
 183             break;
 184     }
 185
 186     if(cc == NULL) {
 187         ap = (u_int8_t *)addr;
 188         if(inet_ntop(af, addr, addrbuf, sizeof(addrbuf)) == NULL) {
 189             *errnop = errno;
 190             *h_errnop = NETDB_INTERNAL;
 191             return(NSS_STATUS_UNAVAIL);
 192         }
 193
 194         if(pipe(pfd)) {
 195             *errnop = errno;
 196             *h_errnop = NETDB_INTERNAL;
 197             return(NSS_STATUS_UNAVAIL);
 198         }
 199         /* I honestly don't know if it is considered OK to fork in other
 200          * people's programs. We need a SUID worker, though, so there's
 201          * little choice that I can see. */
 202         if((child = fork()) < 0) {
 203             *errnop = errno;
 204             *h_errnop = NETDB_INTERNAL;
 205             return(NSS_STATUS_UNAVAIL);
 206         }
 207
 208         if(child == 0) {
 209             int i, fd;
 210             char timeoutbuf[128];
 211
 212             if((fd = open("/dev/null", O_WRONLY)) < 0)
 213                 exit(127);
 214             close(pfd[0]);
 215             dup2(pfd[1], 1);
 216             dup2(fd, 2);
 217             for(i = 3; i < FD_SETSIZE; i++)
 218                 close(i);
 219
 220             if(timeout != -1) {
 221                 snprintf(timeoutbuf, sizeof(timeoutbuf), "%i", timeout);
 222                 execlp("idnlookup", "idnlookup", "-t", timeoutbuf, addrbuf, NULL);
 223             } else {
 224                 execlp("idnlookup", "idnlookup", addrbuf, NULL);
 225             }
 226             exit(127);
 227         }
 228
 229         close(pfd[1]);
 230
 231         rl = 0;
 232         do {
 233             ret = read(pfd[0], addrbuf + rl, sizeof(addrbuf) - rl);
 234             if(ret < 0) {
 235                 *errnop = errno;
 236                 *h_errnop = NETDB_INTERNAL;
 237                 close(pfd[0]);
 238                 return(NSS_STATUS_UNAVAIL);
 239             }
 240             rl += ret;
 241             if(rl >= sizeof(addrbuf) - 1) {
 242                 *errnop = ENOMEM;
 243                 *h_errnop = NETDB_INTERNAL;
 244                 close(pfd[0]);
 245                 return(NSS_STATUS_UNAVAIL);
 246             }
 247         } while(ret != 0);
 248         addrbuf[rl] = 0;
 249         close(pfd[0]);
 250
 251         an = 0;
 252         p = addrbuf;
 253         p3 = buffer + sizeof(*retbuf);
 254         while((p2 = strchr(p, '\n')) != NULL) {
 255             *p2 = 0;
 256             thislen = p2 - p;
 257             if(thislen == 0)
 258                 continue;
 259             if((p3 - buffer) + thislen + 1 > buflen) {
 260                 *errnop = ENOMEM;
 261                 *h_errnop = NETDB_INTERNAL;
 262                 return(NSS_STATUS_UNAVAIL);
 263             }
 264             memcpy(p3, p, thislen + 1);
 265             retbuf->aliaslist[an] = p3;
 266             p3 += thislen + 1;
 267             p = p2 + 1;
 268             if(++an == 16) {
 269                 *errnop = ENOMEM;
 270                 *h_errnop = NETDB_INTERNAL;
 271                 return(NSS_STATUS_UNAVAIL);
 272             }
 273         }
 274         if(an == 0) {
 275             cachenotfound(addr, len, af);
 276             *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */
 277             return(NSS_STATUS_NOTFOUND);
 278         }
 279         retbuf->aliaslist[an] = NULL;
 280     } else {
 281         if(cc->notfound) {
 282             *h_errnop = TRY_AGAIN; /* XXX: Is this correct? */
 283             return(NSS_STATUS_NOTFOUND);
 284         }
 285
 286         p3 = buffer + sizeof(*retbuf);
 287         for(i = 0; cc->names[i] != NULL; i++) {
 288             thislen = strlen(cc->names[i]);
 289             if((p3 - buffer) + thislen + 1 > buflen) {
 290                 *errnop = ENOMEM;
 291                 *h_errnop = NETDB_INTERNAL;
 292                 return(NSS_STATUS_UNAVAIL);
 293             }
 294             memcpy(p3, cc->names[i], thislen + 1);
 295             retbuf->aliaslist[an] = p3;
 296             p3 += thislen + 1;
 297             if(++an == 16) {
 298                 *errnop = ENOMEM;
 299                 *h_errnop = NETDB_INTERNAL;
 300                 return(NSS_STATUS_UNAVAIL);
 301             }
 302         }
 303     }
 304
 305     memcpy(retbuf->retaddr, addr, len);
 306     retbuf->addrlist[0] = retbuf->retaddr;
 307     retbuf->addrlist[1] = NULL;
 308     result->h_name = retbuf->aliaslist[0];
 309     result->h_aliases = retbuf->aliaslist;
 310     result->h_addr_list = retbuf->addrlist;
 311     result->h_addrtype = af;
 312     result->h_length = len;
 313
 314     if(cc == NULL)
 315         updatecache(result);
 316
 317     *h_errnop = NETDB_SUCCESS;
 318     return(NSS_STATUS_SUCCESS);
 319 }