/usr/include/postfix/header_token.h is in postfix-dev 2.9.1-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | #ifndef _HEADER_TOKEN_H_INCLUDED_
#define _HEADER_TOKEN_H_INCLUDED_
/*++
/* NAME
/*	header_token 3h
/* SUMMARY
/*	mail header parser
/* SYNOPSIS
/*	#include "header_token.h"
 DESCRIPTION
 .nf
 /*
  * Utility library.
  */
#include <vstring.h>
 /*
  * HEADER header parser tokens. Specials and controls are represented by
  * themselves. Character pointers point to substrings in a token buffer.
  */
typedef struct HEADER_TOKEN {
    int     type;			/* see below */
    union {
	const char *value;		/* just a pointer, not a copy */
	ssize_t offset;			/* index into token buffer */
    }       u;				/* indent beats any alternative */
} HEADER_TOKEN;
#define HEADER_TOK_TOKEN	256
#define HEADER_TOK_QSTRING	257
extern ssize_t header_token(HEADER_TOKEN *, ssize_t, VSTRING *, const char **, const char *, int);
/* 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
/*--*/
#endif
 |