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/*++
/* NAME
/* is_header 3
/* SUMMARY
/* message header classification
/* SYNOPSIS
/* #include <is_header.h>
/*
/* ssize_t is_header(string)
/* const char *string;
/*
/* ssize_t is_header_buf(string, len)
/* const char *string;
/* ssize_t len;
/* DESCRIPTION
/* is_header() examines the given string and returns non-zero (true)
/* when it begins with a mail header name + optional space + colon.
/* The result is the length of the mail header name.
/*
/* is_header_buf() is a more elaborate interface for use with strings
/* that may not be null terminated.
/* STANDARDS
/* RFC 822 (ARPA Internet Text Messages)
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include "sys_defs.h"
#include <ctype.h>
/* Global library. */
#include "is_header.h"
/* is_header_buf - determine if this can be a header line */
ssize_t is_header_buf(const char *str, ssize_t str_len)
{
const unsigned char *cp;
int state;
int c;
ssize_t len;
#define INIT 0
#define IN_CHAR 1
#define IN_CHAR_SPACE 2
#define CU_CHAR_PTR(x) ((const unsigned char *) (x))
/*
* XXX RFC 2822 Section 4.5, Obsolete header fields: whitespace may
* appear between header label and ":" (see: RFC 822, Section 3.4.2.).
*
* XXX Don't run off the end in case some non-standard iscntrl()
* implementation considers null a non-control character...
*/
for (len = 0, state = INIT, cp = CU_CHAR_PTR(str); /* see below */; cp++) {
if (str_len != IS_HEADER_NULL_TERMINATED && str_len-- <= 0)
return (0);
switch (c = *cp) {
default:
if (c == 0 || !ISASCII(c) || ISCNTRL(c))
return (0);
if (state == INIT)
state = IN_CHAR;
if (state == IN_CHAR) {
len++;
continue;
}
return (0);
case ' ':
case '\t':
if (state == IN_CHAR)
state = IN_CHAR_SPACE;
if (state == IN_CHAR_SPACE)
continue;
return (0);
case ':':
return ((state == IN_CHAR || state == IN_CHAR_SPACE) ? len : 0);
}
}
/* Redundant return for future proofing. */
return (0);
}
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