1 files changed, 92 insertions, 0 deletions
diff --git a/src/global/is_header.c b/src/global/is_header.c
new file mode 100644
index 0000000..891e137
--- /dev/null
+++ b/src/global/is_header.c
@@ -0,0 +1,92 @@
+/*++
+/* 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);
+}