unix4lyfe git - darkstat/blob - db.c

   1 /* darkstat 3
   2  *
   3  * db.c: load and save in-memory database from/to file
   4  * copyright (c) 2007 Ben Stewart, Emil Mikulic.
   5  *
   6  * You may use, modify and redistribute this file under the terms of the
   7  * GNU General Public License version 2. (see COPYING.GPL)
   8  */
   9
  10 #define _GNU_SOURCE 1 /* for O_NOFOLLOW in Linux */
  11
  12 #include <sys/types.h>
  13
  14 #include "darkstat.h"
  15 #include "err.h"
  16 #include "hosts_db.h"
  17 #include "graph_db.h"
  18 #include "db.h"
  19
  20 #include <netinet/in.h> /* for ntohs() and friends */
  21 #include <assert.h>
  22 #include <fcntl.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25
  26 static const unsigned char export_file_header[] = {0xDA, 0x31, 0x41, 0x59};
  27 static const unsigned char export_tag_hosts_ver1[] = {0xDA, 'H', 'S', 0x01};
  28 static const unsigned char export_tag_graph_ver1[] = {0xDA, 'G', 'R', 0x01};
  29
  30 #ifndef swap64
  31 static inline uint64_t
  32 swap64(uint64_t _x)
  33 {
  34    /* this is __bswap64 from:
  35     * $FreeBSD: src/sys/i386/include/endian.h,v 1.41$
  36     */
  37    return ((_x >> 56) | ((_x >> 40) & 0xff00) | ((_x >> 24) & 0xff0000) |
  38           ((_x >> 8) & 0xff000000) | ((_x << 8) & ((uint64_t)0xff << 32)) |
  39           ((_x << 24) & ((uint64_t)0xff << 40)) |
  40           ((_x << 40) & ((uint64_t)0xff << 48)) | ((_x << 56)));
  41 }
  42 #endif
  43
  44 uint64_t
  45 hton64(const uint64_t ho)
  46 {
  47    if (ntohs(0x1234) == 0x1234) return ho;
  48    else return swap64(ho);
  49 }
  50
  51 uint64_t
  52 ntoh64(const uint64_t no)
  53 {
  54    return hton64(no);
  55 }
  56
  57 void
  58 test_64order(void)
  59 {
  60    static const char str[] = { 0x79,0x74,0x69,0x63,0x6b,0x72,0x65,0x6a };
  61    uint64_t no, ho;
  62
  63    assert(sizeof(no) == 8);
  64    memcpy(&no, str, 8);
  65    ho = ntoh64(no);
  66    assert(ho == 8751735851613054314ULL);
  67    assert(hton64(ntoh64(no)) == no);
  68 }
  69
  70 /* ---------------------------------------------------------------------------
  71  * Read-from-file helpers.  They all return 0 on failure, and 1 on success.
  72  */
  73
  74 unsigned int
  75 xtell(const int fd)
  76 {
  77    off_t ofs = lseek(fd, 0, SEEK_CUR);
  78    if (ofs == -1)
  79       err(1, "lseek(0, SEEK_CUR) failed");
  80    return (unsigned int)ofs;
  81 }
  82
  83 /* Read <len> bytes from <fd>, warn() and return 0 on failure,
  84  * or return 1 for success.
  85  */
  86 int
  87 readn(const int fd, void *dest, const size_t len)
  88 {
  89    ssize_t numread;
  90
  91    numread = read(fd, dest, len);
  92    if (numread == (ssize_t)len) return 1;
  93
  94    if (numread == -1)
  95       warn("at pos %u: couldn't read %d bytes", xtell(fd), (int)len);
  96    else
  97       warnx("at pos %u: tried to read %d bytes, got %d",
  98          xtell(fd), (int)len, (int)numread);
  99    return 0;
 100 }
 101
 102 /* Read a byte. */
 103 int
 104 read8(const int fd, uint8_t *dest)
 105 {
 106    assert(sizeof(*dest) == 1);
 107    return readn(fd, dest, sizeof(*dest));
 108 }
 109
 110 /* Read a byte and compare it to the expected data.
 111  * Returns 0 on failure or mismatch, 1 on success.
 112  */
 113 int
 114 expect8(const int fd, uint8_t expecting)
 115 {
 116    uint8_t tmp;
 117
 118    assert(sizeof(tmp) == 1);
 119    if (!readn(fd, &tmp, sizeof(tmp))) return 0;
 120    if (tmp == expecting) return 1;
 121
 122    warnx("at pos %u: expecting 0x%02x, got 0x%02x",
 123       xtell(fd)-1, expecting, tmp);
 124    return 0;
 125 }
 126
 127 /* Read a network order uint16_t from a file
 128  * and store it in host order in memory.
 129  */
 130 int
 131 read16(const int fd, uint16_t *dest)
 132 {
 133    uint16_t tmp;
 134
 135    assert(sizeof(tmp) == 2);
 136    if (!read(fd, &tmp, sizeof(tmp))) return 0;
 137    *dest = ntohs(tmp);
 138    return 1;
 139 }
 140
 141 /* Read a network order uint32_t from a file
 142  * and store it in host order in memory.
 143  */
 144 int
 145 read32(const int fd, uint32_t *dest)
 146 {
 147    uint32_t tmp;
 148
 149    assert(sizeof(tmp) == 4);
 150    if (!read(fd, &tmp, sizeof(tmp))) return 0;
 151    *dest = ntohl(tmp);
 152    return 1;
 153 }
 154
 155 /* Read an in_addr_t from a file.  Addresses are always stored in network
 156  * order, both in the file and in the host's memory (FIXME: is that right?)
 157  */
 158 int
 159 readaddr(const int fd, in_addr_t *dest)
 160 {
 161    assert(sizeof(*dest) == 4);
 162    return readn(fd, dest, sizeof(*dest));
 163 }
 164
 165 /* Read a network order uint64_t from a file
 166  * and store it in host order in memory.
 167  */
 168 int
 169 read64(const int fd, uint64_t *dest)
 170 {
 171    uint64_t tmp;
 172
 173    assert(sizeof(tmp) == 8);
 174    if (!read(fd, &tmp, sizeof(tmp))) return 0;
 175    *dest = ntoh64(tmp);
 176    return 1;
 177 }
 178
 179 /* ---------------------------------------------------------------------------
 180  * Write-to-file helpers.  They all return 0 on failure, and 1 on success.
 181  */
 182
 183 /* Write <len> bytes to <fd>, warn() and return 0 on failure,
 184  * or return 1 for success.
 185  */
 186 int
 187 writen(const int fd, const void *dest, const size_t len)
 188 {
 189    ssize_t numwr;
 190
 191    numwr = write(fd, dest, len);
 192    if (numwr == (ssize_t)len) return 1;
 193
 194    if (numwr == -1)
 195       warn("couldn't write %d bytes", (int)len);
 196    else
 197       warnx("tried to write %d bytes but wrote %d",
 198          (int)len, (int)numwr);
 199    return 0;
 200 }
 201
 202 int
 203 write8(const int fd, const uint8_t i)
 204 {
 205    assert(sizeof(i) == 1);
 206    return writen(fd, &i, sizeof(i));
 207 }
 208
 209 /* Given a uint16_t in host order, write it to a file in network order.
 210  */
 211 int
 212 write16(const int fd, const uint16_t i)
 213 {
 214    uint16_t tmp = htons(i);
 215    assert(sizeof(tmp) == 2);
 216    return writen(fd, &tmp, sizeof(tmp));
 217 }
 218
 219 /* Given a uint32_t in host order, write it to a file in network order.
 220  */
 221 int
 222 write32(const int fd, const uint32_t i)
 223 {
 224    uint32_t tmp = htonl(i);
 225    assert(sizeof(tmp) == 4);
 226    return writen(fd, &tmp, sizeof(tmp));
 227 }
 228
 229 /* Given a uint64_t in host order, write it to a file in network order.
 230  */
 231 int
 232 write64(const int fd, const uint64_t i)
 233 {
 234    uint64_t tmp = hton64(i);
 235    assert(sizeof(tmp) == 8);
 236    return writen(fd, &tmp, sizeof(tmp));
 237 }
 238
 239
 240 /* Write an in_addr_t to a file.  Addresses are always stored in network
 241  * order, both in the file and in the host's memory (FIXME: is that right?)
 242  */
 243 int
 244 writeaddr(const int fd, const in_addr_t addr)
 245 {
 246    assert(sizeof(addr) == 4);
 247    return writen(fd, &addr, sizeof(addr));
 248 }
 249
 250 /* ---------------------------------------------------------------------------
 251  * db import/export code follows.
 252  */
 253
 254 /* Check that the global file header is correct / supported. */
 255 int
 256 read_file_header(const int fd, const uint8_t expected[4])
 257 {
 258    uint8_t got[4];
 259
 260    if (!readn(fd, got, sizeof(got))) return 0;
 261
 262    /* Check the header data */
 263    if (memcmp(got, expected, sizeof(got)) != 0) {
 264       warnx("bad header: "
 265          "expecting %02x%02x%02x%02x, got %02x%02x%02x%02x",
 266          expected[0], expected[1], expected[2], expected[3],
 267          got[0], got[1], got[2], got[3]);
 268       return 0;
 269    }
 270    return 1;
 271 }
 272
 273 /* Returns 0 on failure, 1 on success. */
 274 static int
 275 db_import_from_fd(const int fd)
 276 {
 277    if (!read_file_header(fd, export_file_header)) return 0;
 278    if (!read_file_header(fd, export_tag_hosts_ver1)) return 0;
 279    if (!hosts_db_import(fd)) return 0;
 280    if (!read_file_header(fd, export_tag_graph_ver1)) return 0;
 281    if (!graph_import(fd)) return 0;
 282    return 1;
 283 }
 284
 285 void
 286 db_import(const char *filename)
 287 {
 288    int fd = open(filename, O_RDONLY | O_NOFOLLOW);
 289    if (fd == -1) {
 290       warn("can't import from \"%s\"", filename);
 291       return;
 292    }
 293    if (!db_import_from_fd(fd)) {
 294       warnx("import failed");
 295       /* don't stay in an inconsistent state: */
 296       hosts_db_reset();
 297       graph_reset();
 298    }
 299    close(fd);
 300 }
 301
 302 /* Returns 0 on failure, 1 on success. */
 303 static int
 304 db_export_to_fd(const int fd)
 305 {
 306    if (!writen(fd, export_file_header, sizeof(export_file_header)))
 307       return 0;
 308    if (!writen(fd, export_tag_hosts_ver1, sizeof(export_tag_hosts_ver1)))
 309       return 0;
 310    if (!hosts_db_export(fd))
 311       return 0;
 312    if (!writen(fd, export_tag_graph_ver1, sizeof(export_tag_graph_ver1)))
 313       return 0;
 314    if (!graph_export(fd))
 315       return 0;
 316    return 1;
 317 }
 318
 319 void
 320 db_export(const char *filename)
 321 {
 322    int fd = open(filename, O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC, 0600);
 323    if (fd == -1) {
 324       warn("can't export to \"%s\"", filename);
 325       return;
 326    }
 327    verbosef("exporting db to file \"%s\"", filename);
 328    if (!db_export_to_fd(fd))
 329       warnx("export failed");
 330    else
 331       verbosef("export successful");
 332
 333    /* FIXME: should write to another filename and use the rename() syscall to
 334     * atomically update the output file on success
 335     */
 336    close(fd);
 337 }
 338
 339 /* vim:set ts=3 sw=3 tw=78 et: */