external/ibm-public/postfix/dist/src/util/netstring.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      netstring 3
   6 /* SUMMARY
   7 /*      netstring stream I/O support
   8 /* SYNOPSIS
   9 /*      #include <netstring.h>
  10 /*
  11 /*      void    netstring_setup(stream, timeout)
  12 /*      VSTREAM *stream;
  13 /*      int     timeout;
  14 /*
  15 /*      void    netstring_except(stream, exception)
  16 /*      VSTREAM *stream;
  17 /*      int     exception;
  18 /*
  19 /*      VSTRING *netstring_get(stream, buf, limit)
  20 /*      VSTREAM *stream;
  21 /*      VSTRING *buf;
  22 /*      ssize_t limit;
  23 /*
  24 /*      void    netstring_put(stream, data, len)
  25 /*      VSTREAM *stream;
  26 /*      const char *data;
  27 /*      ssize_t len;
  28 /*
  29 /*      void    netstring_put_multi(stream, data, len, data, len, ..., 0)
  30 /*      VSTREAM *stream;
  31 /*      const char *data;
  32 /*      ssize_t len;
  33 /*
  34 /*      void    NETSTRING_PUT_BUF(stream, buf)
  35 /*      VSTREAM *stream;
  36 /*      VSTRING *buf;
  37 /*
  38 /*      void    netstring_fflush(stream)
  39 /*      VSTREAM *stream;
  40 /*
  41 /*      VSTRING *netstring_memcpy(buf, data, len)
  42 /*      VSTRING *buf;
  43 /*      const char *data;
  44 /*      ssize_t len;
  45 /*
  46 /*      VSTRING *netstring_memcat(buf, data, len)
  47 /*      VSTRING *buf;
  48 /*      const char *src;
  49 /*      ssize_t len;
  50 /* AUXILIARY ROUTINES
  51 /*      ssize_t netstring_get_length(stream)
  52 /*      VSTREAM *stream;
  53 /*
  54 /*      VSTRING *netstring_get_data(stream, buf, len)
  55 /*      VSTREAM *stream;
  56 /*      VSTRING *buf;
  57 /*      ssize_t len;
  58 /*
  59 /*      void    netstring_get_terminator(stream)
  60 /*      VSTREAM *stream;
  61 /* DESCRIPTION
  62 /*      This module reads and writes netstrings with error detection:
  63 /*      timeouts, unexpected end-of-file, or format errors. Netstring
  64 /*      is a data format designed by Daniel Bernstein.
  65 /*
  66 /*      netstring_setup() arranges for a time limit on the netstring
  67 /*      read and write operations described below.
  68 /*      This routine alters the behavior of streams as follows:
  69 /* .IP \(bu
  70 /*      The read/write timeout is set to the specified value.
  71 /* .IP \(bu
  72 /*      The stream is configured to enable exception handling.
  73 /* .PP
  74 /*      netstring_except() raises the specified exception on the
  75 /*      named stream. See the DIAGNOSTICS section below.
  76 /*
  77 /*      netstring_get() reads a netstring from the specified stream
  78 /*      and extracts its content. The limit specifies a maximal size.
  79 /*      Specify zero to disable the size limit. The result is not null
  80 /*      terminated.  The result value is the buf argument.
  81 /*
  82 /*      netstring_put() encapsulates the specified string as a netstring
  83 /*      and sends the result to the specified stream.
  84 /*      The stream output buffer is not flushed.
  85 /*
  86 /*      netstring_put_multi() encapsulates the content of multiple strings
  87 /*      as one netstring and sends the result to the specified stream. The
  88 /*      argument list must be terminated with a null data pointer.
  89 /*      The stream output buffer is not flushed.
  90 /*
  91 /*      NETSTRING_PUT_BUF() is a macro that provides a VSTRING-based
  92 /*      wrapper for the netstring_put() routine.
  93 /*
  94 /*      netstring_fflush() flushes the output buffer of the specified
  95 /*      stream and handles any errors.
  96 /*
  97 /*      netstring_memcpy() encapsulates the specified data as a netstring
  98 /*      and copies the result over the specified buffer. The result
  99 /*      value is the buffer.
 100 /*
 101 /*      netstring_memcat() encapsulates the specified data as a netstring
 102 /*      and appends the result to the specified buffer. The result
 103 /*      value is the buffer.
 104 /*
 105 /*      The following routines provide low-level access to a netstring
 106 /*      stream.
 107 /*
 108 /*      netstring_get_length() reads a length field from the specified
 109 /*      stream, and absorbs the netstring length field terminator.
 110 /*
 111 /*      netstring_get_data() reads the specified number of bytes from the
 112 /*      specified stream into the specified buffer, and absorbs the
 113 /*      netstring terminator.  The result value is the buf argument.
 114 /*
 115 /*      netstring_get_terminator() reads the netstring terminator from
 116 /*      the specified stream.
 117 /* DIAGNOSTICS
 118 /* .fi
 119 /* .ad
 120 /*      In case of error, a vstream_longjmp() call is performed to the
 121 /*      context specified with vstream_setjmp().
 122 /*      Error codes passed along with vstream_longjmp() are:
 123 /* .IP NETSTRING_ERR_EOF
 124 /*      An I/O error happened, or the peer has disconnected unexpectedly.
 125 /* .IP NETSTRING_ERR_TIME
 126 /*      The time limit specified to netstring_setup() was exceeded.
 127 /* .IP NETSTRING_ERR_FORMAT
 128 /*      The input contains an unexpected character value.
 129 /* .IP NETSTRING_ERR_SIZE
 130 /*      The input is larger than acceptable.
 131 /* BUGS
 132 /*      The timeout deadline affects all I/O on the named stream, not
 133 /*      just the I/O done on behalf of this module.
 134 /*
 135 /*      The timeout deadline overwrites any previously set up state on
 136 /*      the named stream.
 137 /*
 138 /*      netstrings are not null terminated, which makes printing them
 139 /*      a bit awkward.
 140 /* LICENSE
 141 /* .ad
 142 /* .fi
 143 /*      The Secure Mailer license must be distributed with this software.
 144 /* SEE ALSO
 145 /*      http://cr.yp.to/proto/netstrings.txt, netstring definition
 146 /* AUTHOR(S)
 147 /*      Wietse Venema
 148 /*      IBM T.J. Watson Research
 149 /*      P.O. Box 704
 150 /*      Yorktown Heights, NY 10598, USA
 151 /*--*/
 152
 153 /* System library. */
 154
 155 #include <sys_defs.h>
 156 #include <stdarg.h>
 157 #include <ctype.h>
 158
 159 /* Utility library. */
 160
 161 #include <msg.h>
 162 #include <vstream.h>
 163 #include <vstring.h>
 164 #include <netstring.h>
 165
 166 /* Application-specific. */
 167
 168 #define STR(x)  vstring_str(x)
 169 #define LEN(x)  VSTRING_LEN(x)
 170
 171 /* netstring_setup - initialize netstring stream */
 172
 173 void    netstring_setup(VSTREAM *stream, int timeout)
 174 {
 175     vstream_control(stream,
 176                     VSTREAM_CTL_TIMEOUT, timeout,
 177                     VSTREAM_CTL_EXCEPT,
 178                     VSTREAM_CTL_END);
 179 }
 180
 181 /* netstring_except - process netstring stream exception */
 182
 183 void    netstring_except(VSTREAM *stream, int exception)
 184 {
 185     vstream_longjmp(stream, exception);
 186 }
 187
 188 /* netstring_get_length - read netstring length + terminator */
 189
 190 ssize_t netstring_get_length(VSTREAM *stream)
 191 {
 192     const char *myname = "netstring_get_length";
 193     ssize_t len = 0;
 194     int     ch;
 195
 196     for (;;) {
 197         switch (ch = VSTREAM_GETC(stream)) {
 198         case VSTREAM_EOF:
 199             netstring_except(stream, vstream_ftimeout(stream) ?
 200                              NETSTRING_ERR_TIME : NETSTRING_ERR_EOF);
 201         case ':':
 202             if (msg_verbose > 1)
 203                 msg_info("%s: read netstring length %ld", myname, (long) len);
 204             return (len);
 205         default:
 206             if (!ISDIGIT(ch))
 207                 netstring_except(stream, NETSTRING_ERR_FORMAT);
 208             len = len * 10 + ch - '0';
 209             /* vstream_fread() would read zero bytes. Reject input anyway. */
 210             if (len < 0)
 211                 netstring_except(stream, NETSTRING_ERR_SIZE);
 212             break;
 213         }
 214     }
 215 }
 216
 217 /* netstring_get_data - read netstring payload + terminator */
 218
 219 VSTRING *netstring_get_data(VSTREAM *stream, VSTRING *buf, ssize_t len)
 220 {
 221     const char *myname = "netstring_get_data";
 222
 223     /*
 224      * Allocate buffer space.
 225      */
 226     VSTRING_RESET(buf);
 227     VSTRING_SPACE(buf, len);
 228
 229     /*
 230      * Read the payload and absorb the terminator.
 231      */
 232     if (vstream_fread(stream, STR(buf), len) != len)
 233         netstring_except(stream, vstream_ftimeout(stream) ?
 234                          NETSTRING_ERR_TIME : NETSTRING_ERR_EOF);
 235     if (msg_verbose > 1)
 236         msg_info("%s: read netstring data %.*s",
 237                  myname, (int) (len < 30 ? len : 30), STR(buf));
 238     netstring_get_terminator(stream);
 239
 240     /*
 241      * Position the buffer.
 242      */
 243     VSTRING_AT_OFFSET(buf, len);
 244     return (buf);
 245 }
 246
 247 /* netstring_get_terminator - absorb netstring terminator */
 248
 249 void    netstring_get_terminator(VSTREAM *stream)
 250 {
 251     if (VSTREAM_GETC(stream) != ',')
 252         netstring_except(stream, NETSTRING_ERR_FORMAT);
 253 }
 254
 255 /* netstring_get - read string from netstring stream */
 256
 257 VSTRING *netstring_get(VSTREAM *stream, VSTRING *buf, ssize_t limit)
 258 {
 259     ssize_t len;
 260
 261     len = netstring_get_length(stream);
 262     if (limit && len > limit)
 263         netstring_except(stream, NETSTRING_ERR_SIZE);
 264     netstring_get_data(stream, buf, len);
 265     return (buf);
 266 }
 267
 268 /* netstring_put - send string as netstring */
 269
 270 void    netstring_put(VSTREAM *stream, const char *data, ssize_t len)
 271 {
 272     const char *myname = "netstring_put";
 273
 274     if (msg_verbose > 1)
 275         msg_info("%s: write netstring len %ld data %.*s",
 276                  myname, (long) len, (int) (len < 30 ? len : 30), data);
 277     vstream_fprintf(stream, "%ld:", (long) len);
 278     vstream_fwrite(stream, data, len);
 279     VSTREAM_PUTC(',', stream);
 280 }
 281
 282 /* netstring_put_multi - send multiple strings as one netstring */
 283
 284 void    netstring_put_multi(VSTREAM *stream,...)
 285 {
 286     const char *myname = "netstring_put_multi";
 287     ssize_t total;
 288     char   *data;
 289     ssize_t data_len;
 290     va_list ap;
 291
 292     /*
 293      * Figure out the total result size.
 294      */
 295     va_start(ap, stream);
 296     for (total = 0; (data = va_arg(ap, char *)) != 0; total += data_len)
 297         if ((data_len = va_arg(ap, ssize_t)) < 0)
 298             msg_panic("netstring_put_multi: bad data length %ld", (long) data_len);
 299     va_end(ap);
 300
 301     /*
 302      * Debugging support.
 303      */
 304     if (msg_verbose > 1) {
 305         va_start(ap, stream);
 306         data = va_arg(ap, char *);
 307         data_len = va_arg(ap, ssize_t);
 308         msg_info("%s: write netstring len %ld data %.*s",
 309          myname, (long) total, (int) (data_len < 30 ? data_len : 30), data);
 310         va_end(ap);
 311     }
 312
 313     /*
 314      * Send the length, content and terminator.
 315      */
 316     vstream_fprintf(stream, "%ld:", (long) total);
 317     va_start(ap, stream);
 318     while ((data = va_arg(ap, char *)) != 0) {
 319         data_len = va_arg(ap, ssize_t);
 320         if (data_len > 0)
 321             if (vstream_fwrite(stream, data, data_len) != data_len)
 322                 netstring_except(stream, vstream_ftimeout(stream) ?
 323                                  NETSTRING_ERR_TIME : NETSTRING_ERR_EOF);
 324     }
 325     va_end(ap);
 326     vstream_fwrite(stream, ",", 1);
 327 }
 328
 329 /* netstring_fflush - flush netstring stream */
 330
 331 void    netstring_fflush(VSTREAM *stream)
 332 {
 333     if (vstream_fflush(stream) == VSTREAM_EOF)
 334         netstring_except(stream, vstream_ftimeout(stream) ?
 335                          NETSTRING_ERR_TIME : NETSTRING_ERR_EOF);
 336 }
 337
 338 /* netstring_memcpy - copy data as in-memory netstring */
 339
 340 VSTRING *netstring_memcpy(VSTRING *buf, const char *src, ssize_t len)
 341 {
 342     vstring_sprintf(buf, "%ld:", (long) len);
 343     vstring_memcat(buf, src, len);
 344     VSTRING_ADDCH(buf, ',');
 345     return (buf);
 346 }
 347
 348 /* netstring_memcat - append data as in-memory netstring */
 349
 350 VSTRING *netstring_memcat(VSTRING *buf, const char *src, ssize_t len)
 351 {
 352     vstring_sprintf_append(buf, "%ld:", (long) len);
 353     vstring_memcat(buf, src, len);
 354     VSTRING_ADDCH(buf, ',');
 355     return (buf);
 356 }