1 /* $NetBSD: hex_quote.c,v 1.2 2020/03/18 19:05:21 christos Exp $ */
2
3 /*++
4 /* NAME
5 /* hex_quote 3
6 /* SUMMARY
7 /* quote/unquote text, HTTP style.
8 /* SYNOPSIS
9 /* #include <hex_quote.h>
10 /*
11 /* VSTRING *hex_quote(hex, raw)
12 /* VSTRING *hex;
13 /* const char *raw;
14 /*
15 /* VSTRING *hex_unquote(raw, hex)
16 /* VSTRING *raw;
17 /* const char *hex;
18 /* DESCRIPTION
19 /* hex_quote() takes a null-terminated string and replaces non-printable
20 /* and whitespace characters and the % by %XX, XX being the two-digit
21 /* hexadecimal equivalent.
22 /* The hexadecimal codes are produced as upper-case characters. The result
23 /* value is the hex argument.
24 /*
25 /* hex_unquote() performs the opposite transformation. This function
26 /* understands lowercase, uppercase, and mixed case %XX sequences. The
27 /* result value is the raw argument in case of success, a null pointer
28 /* otherwise.
29 /* BUGS
30 /* hex_quote() cannot process null characters in data.
31 /* LICENSE
32 /* .ad
33 /* .fi
34 /* The Secure Mailer license must be distributed with this software.
35 /* AUTHOR(S)
36 /* Wietse Venema
37 /* IBM T.J. Watson Research
38 /* P.O. Box 704
39 /* Yorktown Heights, NY 10598, USA
40 /*
41 /* Wietse Venema
42 /* Google, Inc.
43 /* 111 8th Avenue
44 /* New York, NY 10011, USA
45 /*--*/
46
47 /* System library. */
48
49 #include "sys_defs.h"
50 #include <ctype.h>
51
52 /* Utility library. */
53
54 #include "msg.h"
55 #include "vstring.h"
56 #include "hex_quote.h"
57
58 /* Application-specific. */
59
60 #define STR(x) vstring_str(x)
61 #define LEN(x) VSTRING_LEN(x)
62
63 /* hex_quote - raw data to quoted */
64
hex_quote(VSTRING * hex,const char * raw)65 VSTRING *hex_quote(VSTRING *hex, const char *raw)
66 {
67 const char *cp;
68 int ch;
69
70 VSTRING_RESET(hex);
71 for (cp = raw; (ch = *(unsigned const char *) cp) != 0; cp++) {
72 if (ch != '%' && !ISSPACE(ch) && ISPRINT(ch)) {
73 VSTRING_ADDCH(hex, ch);
74 } else {
75 vstring_sprintf_append(hex, "%%%02X", ch);
76 }
77 }
78 VSTRING_TERMINATE(hex);
79 return (hex);
80 }
81
82 /* hex_unquote - quoted data to raw */
83
hex_unquote(VSTRING * raw,const char * hex)84 VSTRING *hex_unquote(VSTRING *raw, const char *hex)
85 {
86 const char *cp;
87 int ch;
88
89 VSTRING_RESET(raw);
90 for (cp = hex; (ch = *cp) != 0; cp++) {
91 if (ch == '%') {
92 if (ISDIGIT(cp[1]))
93 ch = (cp[1] - '0') << 4;
94 else if (cp[1] >= 'a' && cp[1] <= 'f')
95 ch = (cp[1] - 'a' + 10) << 4;
96 else if (cp[1] >= 'A' && cp[1] <= 'F')
97 ch = (cp[1] - 'A' + 10) << 4;
98 else
99 return (0);
100 if (ISDIGIT(cp[2]))
101 ch |= (cp[2] - '0');
102 else if (cp[2] >= 'a' && cp[2] <= 'f')
103 ch |= (cp[2] - 'a' + 10);
104 else if (cp[2] >= 'A' && cp[2] <= 'F')
105 ch |= (cp[2] - 'A' + 10);
106 else
107 return (0);
108 cp += 2;
109 }
110 VSTRING_ADDCH(raw, ch);
111 }
112 VSTRING_TERMINATE(raw);
113 return (raw);
114 }
115
116 #ifdef TEST
117
118 /*
119 * Proof-of-concept test program: convert to hex and back.
120 */
121 #include <vstream.h>
122
123 #define BUFLEN 1024
124
read_buf(VSTREAM * fp,VSTRING * buf)125 static ssize_t read_buf(VSTREAM *fp, VSTRING *buf)
126 {
127 ssize_t len;
128
129 len = vstream_fread_buf(fp, buf, BUFLEN);
130 VSTRING_TERMINATE(buf);
131 return (len);
132 }
133
main(int unused_argc,char ** unused_argv)134 int main(int unused_argc, char **unused_argv)
135 {
136 VSTRING *raw = vstring_alloc(BUFLEN);
137 VSTRING *hex = vstring_alloc(100);
138 ssize_t len;
139
140 while ((len = read_buf(VSTREAM_IN, raw)) > 0) {
141 hex_quote(hex, STR(raw));
142 if (hex_unquote(raw, STR(hex)) == 0)
143 msg_fatal("bad input: %.100s", STR(hex));
144 if (LEN(raw) != len)
145 msg_fatal("len %ld != raw len %ld", (long) len, (long) LEN(raw));
146 if (vstream_fwrite(VSTREAM_OUT, STR(raw), LEN(raw)) != LEN(raw))
147 msg_fatal("write error: %m");
148 }
149 vstream_fflush(VSTREAM_OUT);
150 vstring_free(raw);
151 vstring_free(hex);
152 return (0);
153 }
154
155 #endif
156