external/ibm-public/postfix/dist/src/global/is_header.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      is_header 3
   6 /* SUMMARY
   7 /*      message header classification
   8 /* SYNOPSIS
   9 /*      #include <is_header.h>
  10 /*
  11 /*      ssize_t is_header(string)
  12 /*      const char *string;
  13 /*
  14 /*      ssize_t is_header_buf(string, len)
  15 /*      const char *string;
  16 /*      ssize_t len;
  17 /* DESCRIPTION
  18 /*      is_header() examines the given string and returns non-zero (true)
  19 /*      when it begins with a mail header name + optional space + colon.
  20 /*      The result is the length of the mail header name.
  21 /*
  22 /*      is_header_buf() is a more elaborate interface for use with strings
  23 /*      that may not be null terminated.
  24 /* STANDARDS
  25 /*      RFC 822 (ARPA Internet Text Messages)
  26 /* LICENSE
  27 /* .ad
  28 /* .fi
  29 /*      The Secure Mailer license must be distributed with this software.
  30 /* AUTHOR(S)
  31 /*      Wietse Venema
  32 /*      IBM T.J. Watson Research
  33 /*      P.O. Box 704
  34 /*      Yorktown Heights, NY 10598, USA
  35 /*--*/
  36
  37 /* System library. */
  38
  39 #include "sys_defs.h"
  40 #include <ctype.h>
  41
  42 /* Global library. */
  43
  44 #include "is_header.h"
  45
  46 /* is_header_buf - determine if this can be a header line */
  47
  48 ssize_t is_header_buf(const char *str, ssize_t str_len)
  49 {
  50     const unsigned char *cp;
  51     int     state;
  52     int     c;
  53     ssize_t len;
  54
  55 #define INIT            0
  56 #define IN_CHAR         1
  57 #define IN_CHAR_SPACE   2
  58 #define CU_CHAR_PTR(x)  ((const unsigned char *) (x))
  59
  60     /*
  61      * XXX RFC 2822 Section 4.5, Obsolete header fields: whitespace may
  62      * appear between header label and ":" (see: RFC 822, Section 3.4.2.).
  63      *
  64      * XXX Don't run off the end in case some non-standard iscntrl()
  65      * implementation considers null a non-control character...
  66      */
  67     for (len = 0, state = INIT, cp = CU_CHAR_PTR(str); /* see below */; cp++) {
  68         if (str_len != IS_HEADER_NULL_TERMINATED && str_len-- <= 0)
  69             return (0);
  70         switch (c = *cp) {
  71         default:
  72             if (c == 0 || !ISASCII(c) || ISCNTRL(c))
  73                 return (0);
  74             if (state == INIT)
  75                 state = IN_CHAR;
  76             if (state == IN_CHAR) {
  77                 len++;
  78                 continue;
  79             }
  80             return (0);
  81         case ' ':
  82         case '\t':
  83             if (state == IN_CHAR)
  84                 state = IN_CHAR_SPACE;
  85             if (state == IN_CHAR_SPACE)
  86                 continue;
  87             return (0);
  88         case ':':
  89             return ((state == IN_CHAR || state == IN_CHAR_SPACE) ? len : 0);
  90         }
  91     }
  92     /* Redundant return for future proofing. */
  93     return (0);
  94 }