1/*++
2/* NAME
3/*	xtext 3
4/* SUMMARY
5/*	quote/unquote text, xtext style.
6/* SYNOPSIS
7/*	#include <xtext.h>
8/*
9/*	VSTRING	*xtext_quote(quoted, unquoted, special)
10/*	VSTRING	*quoted;
11/*	const char *unquoted;
12/*	const char *special;
13/*
14/*	VSTRING	*xtext_quote_append(unquoted, quoted, special)
15/*	VSTRING	*unquoted;
16/*	const char *quoted;
17/*	const char *special;
18/*
19/*	VSTRING	*xtext_unquote(unquoted, quoted)
20/*	VSTRING	*unquoted;
21/*	const char *quoted;
22/* DESCRIPTION
23/*	xtext_quote() takes a null-terminated string and replaces characters
24/*	+, <33(10) and >126(10), as well as characters specified with "special"
25/*	by +XX, XX being the two-digit uppercase hexadecimal equivalent.
26/*
27/*	xtext_quote_append() is like xtext_quote(), but appends the conversion
28/*	result to the result buffer.
29/*
30/*	xtext_unquote() performs the opposite transformation. This function
31/*	understands lowercase, uppercase, and mixed case +XX sequences. The
32/*	result value is the unquoted argument in case of success, a null pointer
33/*	otherwise.
34/* BUGS
35/*	This module cannot process null characters in data.
36/* LICENSE
37/* .ad
38/* .fi
39/*	The Secure Mailer license must be distributed with this software.
40/* AUTHOR(S)
41/*	Wietse Venema
42/*	IBM T.J. Watson Research
43/*	P.O. Box 704
44/*	Yorktown Heights, NY 10598, USA
45/*--*/
46
47/* System library. */
48
49#include <sys_defs.h>
50#include <string.h>
51#include <ctype.h>
52
53/* Utility library. */
54
55#include "msg.h"
56#include "vstring.h"
57#include "xtext.h"
58
59/* Application-specific. */
60
61#define STR(x)	vstring_str(x)
62#define LEN(x)	VSTRING_LEN(x)
63
64/* xtext_quote_append - append unquoted data to quoted data */
65
66VSTRING *xtext_quote_append(VSTRING *quoted, const char *unquoted,
67			            const char *special)
68{
69    const char *cp;
70    int     ch;
71
72    for (cp = unquoted; (ch = *(unsigned const char *) cp) != 0; cp++) {
73	if (ch != '+' && ch > 32 && ch < 127
74	    && (*special == 0 || strchr(special, ch) == 0)) {
75	    VSTRING_ADDCH(quoted, ch);
76	} else {
77	    vstring_sprintf_append(quoted, "+%02X", ch);
78	}
79    }
80    VSTRING_TERMINATE(quoted);
81    return (quoted);
82}
83
84/* xtext_quote - unquoted data to quoted */
85
86VSTRING *xtext_quote(VSTRING *quoted, const char *unquoted, const char *special)
87{
88    VSTRING_RESET(quoted);
89    xtext_quote_append(quoted, unquoted, special);
90    return (quoted);
91}
92
93/* xtext_unquote - quoted data to unquoted */
94
95VSTRING *xtext_unquote(VSTRING *unquoted, const char *quoted)
96{
97    const char *cp;
98    int     ch;
99
100    VSTRING_RESET(unquoted);
101    for (cp = quoted; (ch = *cp) != 0; cp++) {
102	if (ch == '+') {
103	    if (ISDIGIT(cp[1]))
104		ch = (cp[1] - '0') << 4;
105	    else if (cp[1] >= 'a' && cp[1] <= 'f')
106		ch = (cp[1] - 'a' + 10) << 4;
107	    else if (cp[1] >= 'A' && cp[1] <= 'F')
108		ch = (cp[1] - 'A' + 10) << 4;
109	    else
110		return (0);
111	    if (ISDIGIT(cp[2]))
112		ch |= (cp[2] - '0');
113	    else if (cp[2] >= 'a' && cp[2] <= 'f')
114		ch |= (cp[2] - 'a' + 10);
115	    else if (cp[2] >= 'A' && cp[2] <= 'F')
116		ch |= (cp[2] - 'A' + 10);
117	    else
118		return (0);
119	    cp += 2;
120	}
121	VSTRING_ADDCH(unquoted, ch);
122    }
123    VSTRING_TERMINATE(unquoted);
124    return (unquoted);
125}
126
127#ifdef TEST
128
129 /*
130  * Proof-of-concept test program: convert to quoted and back.
131  */
132#include <vstream.h>
133
134#define BUFLEN 1024
135
136static ssize_t read_buf(VSTREAM *fp, VSTRING *buf)
137{
138    ssize_t len;
139
140    VSTRING_RESET(buf);
141    len = vstream_fread(fp, STR(buf), vstring_avail(buf));
142    VSTRING_AT_OFFSET(buf, len);		/* XXX */
143    VSTRING_TERMINATE(buf);
144    return (len);
145}
146
147int     main(int unused_argc, char **unused_argv)
148{
149    VSTRING *unquoted = vstring_alloc(BUFLEN);
150    VSTRING *quoted = vstring_alloc(100);
151    ssize_t len;
152
153    while ((len = read_buf(VSTREAM_IN, unquoted)) > 0) {
154	xtext_quote(quoted, STR(unquoted), "+=");
155	if (xtext_unquote(unquoted, STR(quoted)) == 0)
156	    msg_fatal("bad input: %.100s", STR(quoted));
157	if (LEN(unquoted) != len)
158	    msg_fatal("len %ld != unquoted len %ld",
159		      (long) len, (long) LEN(unquoted));
160	if (vstream_fwrite(VSTREAM_OUT, STR(unquoted), LEN(unquoted)) != LEN(unquoted))
161	    msg_fatal("write error: %m");
162    }
163    vstream_fflush(VSTREAM_OUT);
164    vstring_free(unquoted);
165    vstring_free(quoted);
166    return (0);
167}
168
169#endif
170