unix4lyfe git - darkstat-debian/blob - conv.c

   1 /* darkstat 3
   2  * copyright (c) 2001-2014 Emil Mikulic.
   3  *
   4  * conv.c: convenience functions.
   5  *
   6  * Permission to use, copy, modify, and distribute this file for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include "conv.h"
  20
  21 #include <sys/wait.h>
  22 #include <assert.h>
  23 #include <ctype.h>
  24 #include "err.h"
  25 #include <errno.h>
  26 #include <fcntl.h>
  27 #include <pwd.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <time.h>
  32 #include <unistd.h>
  33 #include <limits.h>
  34
  35 #define PATH_DEVNULL "/dev/null"
  36
  37 /* malloc() that exits on failure. */
  38 void *
  39 xmalloc(const size_t size)
  40 {
  41    void *ptr = malloc(size);
  42
  43    if (ptr == NULL)
  44       errx(1, "malloc(): out of memory");
  45    return (ptr);
  46 }
  47
  48 /* calloc() that exits on failure. */
  49 void *
  50 xcalloc(const size_t num, const size_t size)
  51 {
  52    void *ptr = calloc(num, size);
  53
  54    if (ptr == NULL)
  55       errx(1, "calloc(): out of memory");
  56    return (ptr);
  57 }
  58
  59 /* realloc() that exits on failure. */
  60 void *
  61 xrealloc(void *original, const size_t size)
  62 {
  63     void *ptr = realloc(original, size);
  64
  65     if (ptr == NULL)
  66       errx(1, "realloc(): out of memory");
  67     return (ptr);
  68 }
  69
  70 /* strdup() that exits on failure. */
  71 char *
  72 xstrdup(const char *s)
  73 {
  74    char *tmp = strdup(s);
  75
  76    if (tmp == NULL)
  77       errx(1, "strdup(): out of memory");
  78    return (tmp);
  79 }
  80
  81 /* ---------------------------------------------------------------------------
  82  * Split string out of src with range [left:right-1]
  83  */
  84 char *
  85 split_string(const char *src, const size_t left, const size_t right)
  86 {
  87     char *dest;
  88     assert(left <= right);
  89     assert(left < strlen(src));   /* [left means must be smaller */
  90     assert(right <= strlen(src)); /* right) means can be equal or smaller */
  91
  92     dest = xmalloc(right - left + 1);
  93     memcpy(dest, src+left, right-left);
  94     dest[right-left] = '\0';
  95     return (dest);
  96 }
  97
  98 /* ---------------------------------------------------------------------------
  99  * Uppercasify all characters in a string of given length.
 100  */
 101 void
 102 strntoupper(char *str, const size_t length)
 103 {
 104     size_t i;
 105
 106     for (i=0; i<length; i++)
 107         str[i] = toupper(str[i]);
 108 }
 109
 110 /* ---------------------------------------------------------------------------
 111  * Returns non-zero if haystack starts with needle.
 112  */
 113 int
 114 str_starts_with(const char *haystack, const char *needle)
 115 {
 116    int i = 0;
 117
 118    while (needle[i] != '\0') {
 119       if ((haystack[i] == '\0') || (haystack[i] != needle[i]))
 120          return (0);
 121       i++;
 122    }
 123    return (1);
 124 }
 125
 126 /* split - splits a string by a delimiter character into an array of
 127  * string chunks.
 128  *
 129  * The chunks and the array are dynamically allocated using xmalloc() so
 130  * it will errx() if it runs out of memory.
 131  *
 132  *    int num_chunks;
 133  *    char **chunks = split('.', "..one...two....", &num_chunks);
 134  *
 135  *    num_chunks = 2, chunks = { "one", "two", NULL }
 136  */
 137 char **
 138 split(const char delimiter, const char *str, unsigned int *num_chunks)
 139 {
 140    unsigned int num = 0;
 141    char **chunks = NULL;
 142    size_t left, right = 0;
 143
 144    #define PUSH(c) do { num++;  chunks = (char**) xrealloc(chunks, \
 145       sizeof(*chunks) * num);  chunks[num-1] = c; } while(0)
 146
 147    for(;;) {
 148       /* find first non-delimiter */
 149       for (left = right; str[left] == delimiter; left++)
 150             ;
 151
 152       if (str[left] == '\0')
 153          break; /* ran out of string */
 154
 155       /* find first delimiter or end of string */
 156       for (right=left+1;
 157          str[right] != delimiter && str[right] != '\0';
 158          right++)
 159             ;
 160
 161       /* split chunk out */
 162       PUSH( split_string(str, left, right) );
 163
 164       if (str[right] == '\0')
 165          break; /* ran out of string */
 166       else
 167          right++;
 168    }
 169
 170    /* return */
 171    PUSH(NULL);
 172    if (num_chunks != NULL)
 173       *num_chunks = num-1; /* NULL doesn't count */
 174    return (chunks);
 175    #undef PUSH
 176 }
 177
 178 /* Given an HTTP query string and a key to search for, return the value
 179  * associated with it, or NULL if there is no such key or qs is NULL.
 180  * The returned string needs to be freed.
 181  *
 182  * e.g.:
 183  * qs = "sort=in&start=20";
 184  * qs_get(sq, "sort") returns "in"
 185  * qs_get(sq, "end") returns NULL
 186  */
 187 char *
 188 qs_get(const char *qs, const char *key)
 189 {
 190    size_t pos, qslen, keylen;
 191
 192    if (qs == NULL) return NULL;
 193
 194    qslen = strlen(qs);
 195    keylen = strlen(key);
 196    pos = 0;
 197    while (pos < qslen) {
 198       if (!(pos + keylen + 1 < qslen))
 199          /* not enough room for "key" + "=" */
 200          return NULL;
 201       else {
 202          if (str_starts_with(qs+pos, key) && qs[pos+keylen] == '=') {
 203             /* found key= */
 204             size_t start, end;
 205
 206             start = pos + keylen + 1;
 207             for (end=start; end<qslen && qs[end] != '&'; end++)
 208                ;
 209             return split_string(qs, start, end);
 210          } else {
 211             /* didn't find key, skip to next & */
 212             do { pos++; } while ((pos < qslen) && (qs[pos] != '&'));
 213             pos++; /* skip the ampersand */
 214          }
 215       }
 216    }
 217    return NULL; /* not found */
 218 }
 219
 220 static int lifeline[2] = { -1, -1 };
 221 static int fd_null = -1;
 222
 223 void
 224 daemonize_start(void)
 225 {
 226    pid_t f, w;
 227
 228    if (pipe(lifeline) == -1)
 229       err(1, "pipe(lifeline)");
 230
 231    fd_null = open(PATH_DEVNULL, O_RDWR, 0);
 232    if (fd_null == -1)
 233       err(1, "open(" PATH_DEVNULL ")");
 234
 235    f = fork();
 236    if (f == -1)
 237       err(1, "fork");
 238    else if (f != 0) {
 239       /* parent: wait for child */
 240       char tmp[1];
 241       int status;
 242
 243       verbosef("parent waiting");
 244       if (close(lifeline[1]) == -1)
 245          warn("close lifeline in parent");
 246       if (read(lifeline[0], tmp, sizeof(tmp)) != 0) /* expecting EOF */
 247          err(1, "lifeline read() failed");
 248       verbosef("parent done reading, calling waitpid");
 249       w = waitpid(f, &status, WNOHANG);
 250       verbosef("waitpid ret %d, status is %d", w, status);
 251       if (w == -1)
 252          err(1, "waitpid");
 253       else if (w == 0)
 254          /* child is running happily */
 255          exit(EXIT_SUCCESS);
 256       else
 257          /* child init failed, pass on its exit status */
 258          exit(WEXITSTATUS(status));
 259    }
 260    /* else we are the child: continue initializing */
 261 }
 262
 263 void
 264 daemonize_finish(void)
 265 {
 266    if (fd_null == -1)
 267       return; /* didn't daemonize_start(), i.e. we're not daemonizing */
 268
 269    if (setsid() == -1)
 270       err(1, "setsid");
 271    if (close(lifeline[0]) == -1)
 272       warn("close read end of lifeline in child");
 273    if (close(lifeline[1]) == -1)
 274       warn("couldn't cut the lifeline");
 275
 276    /* close all our std fds */
 277    if (dup2(fd_null, STDIN_FILENO) == -1)
 278       warn("dup2(stdin)");
 279    if (dup2(fd_null, STDOUT_FILENO) == -1)
 280       warn("dup2(stdout)");
 281    if (dup2(fd_null, STDERR_FILENO) == -1)
 282       warn("dup2(stderr)");
 283    if (fd_null > 2)
 284       close(fd_null);
 285 }
 286
 287 /*
 288  * For security, chroot (optionally) and drop privileges.
 289  * Pass a NULL chroot_dir to disable chroot() behaviour.
 290  */
 291 void privdrop(const char *chroot_dir, const char *privdrop_user) {
 292    struct passwd *pw;
 293
 294    errno = 0;
 295    pw = getpwnam(privdrop_user);
 296
 297    if (pw == NULL) {
 298       if (errno == 0)
 299          errx(1, "getpwnam(\"%s\") failed: no such user", privdrop_user);
 300       else
 301          err(1, "getpwnam(\"%s\") failed", privdrop_user);
 302    }
 303    if (chroot_dir == NULL) {
 304       verbosef("no --chroot dir specified, darkstat will not chroot()");
 305    } else {
 306       tzset(); /* read /etc/localtime before we chroot */
 307       if (chdir(chroot_dir) == -1)
 308          err(1, "chdir(\"%s\") failed", chroot_dir);
 309       if (chroot(chroot_dir) == -1)
 310          err(1, "chroot(\"%s\") failed", chroot_dir);
 311       verbosef("chrooted into: %s", chroot_dir);
 312    }
 313    if (setgid(pw->pw_gid) == -1)
 314       err(1, "setgid");
 315    if (setuid(pw->pw_uid) == -1)
 316       err(1, "setuid");
 317    verbosef("set uid/gid to %d/%d", (int)pw->pw_uid, (int)pw->pw_gid);
 318 }
 319
 320 /* Make the specified file descriptor non-blocking. */
 321 void
 322 fd_set_nonblock(const int fd)
 323 {
 324    int flags;
 325
 326    if ((flags = fcntl(fd, F_GETFL, 0)) == -1)
 327       err(1, "fcntl(fd %d) to get flags", fd);
 328    flags |= O_NONBLOCK;
 329    if (fcntl(fd, F_SETFL, flags) == -1)
 330       err(1, "fcntl(fd %d) to set O_NONBLOCK", fd);
 331    assert( (fcntl(fd, F_GETFL, 0) & O_NONBLOCK ) == O_NONBLOCK );
 332 }
 333
 334 /* Make the specified file descriptor blocking. */
 335 void
 336 fd_set_block(const int fd)
 337 {
 338    int flags;
 339
 340    if ((flags = fcntl(fd, F_GETFL, 0)) == -1)
 341       err(1, "fcntl(fd %d) to get flags", fd);
 342    flags &= ~O_NONBLOCK;
 343    if (fcntl(fd, F_SETFL, flags) == -1)
 344       err(1, "fcntl(fd %d) to unset O_NONBLOCK", fd);
 345    assert( (fcntl(fd, F_GETFL, 0) & O_NONBLOCK ) == 0 );
 346 }
 347
 348 /* vim:set ts=3 sw=3 tw=78 expandtab: */