1 /*
2  * Copyright (c) 2019 Ori Bernstein <ori@openbsd.org>
3  * Copyright (c) 2021 Stefan Sperling <stsp@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <ctype.h>
19 #include <errno.h>
20 #include <limits.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <unistd.h>
24 
25 #include "got_error.h"
26 #include "got_lib_pkt.h"
27 
28 const struct got_error *
29 got_pkt_readn(ssize_t *off, int fd, void *buf, size_t n)
30 {
31 	ssize_t r;
32 
33 	*off = 0;
34 	while (*off != n) {
35 		r = read(fd, buf + *off, n - *off);
36 		if (r == -1)
37 			return got_error_from_errno("read");
38 		if (r == 0)
39 			return got_error(GOT_ERR_EOF);
40 		*off += r;
41 	}
42 	return NULL;
43 }
44 
45 const struct got_error *
46 got_pkt_flushpkt(int fd, int chattygot)
47 {
48 	ssize_t w;
49 
50 	if (chattygot > 1)
51 		fprintf(stderr, "%s: writepkt: 0000\n", getprogname());
52 
53 	w = write(fd, "0000", 4);
54 	if (w == -1)
55 		return got_error_from_errno("write");
56 	if (w != 4)
57 		return got_error(GOT_ERR_IO);
58 	return NULL;
59 }
60 
61 const struct got_error *
62 got_pkt_readlen(int *len, const char *str, int chattygot)
63 {
64 	int	 i;
65 
66 	*len = 0;
67 	for (i = 0; i < 4; i++) {
68 		if ('0' <= str[i] && str[i] <= '9') {
69 			*len *= 16;
70 			*len += str[i] - '0';
71 		} else if ('a' <= str[i] && str[i] <= 'f') {
72 			*len *= 16;
73 			*len += str[i] - 'a' + 10;
74 		} else {
75 			if (chattygot)
76 				fprintf(stderr, "%s: bad length: '.4%s'\n",
77 				    getprogname(), str);
78 			return got_error_msg(GOT_ERR_BAD_PACKET,
79 			    "packet length has invalid format");
80 		}
81 	}
82 	return NULL;
83 }
84 
85 /*
86  * Packet header contains a 4-byte hexstring which specifies the length
87  * of data which follows.
88  */
89 const struct got_error *
90 got_pkt_readhdr(int *datalen, int fd, int chattygot)
91 {
92 	static const struct got_error *err;
93 	char lenstr[4];
94 	ssize_t r;
95 	int n;
96 
97 	*datalen = 0;
98 
99 	err = got_pkt_readn(&r, fd, lenstr, 4);
100 	if (err)
101 		return err;
102 	if (r == 0) {
103 		/* implicit "0000" */
104 		if (chattygot > 1)
105 			fprintf(stderr, "%s: readpkt: 0000\n", getprogname());
106 		return NULL;
107 	}
108 	if (r != 4)
109 		return got_error_msg(GOT_ERR_BAD_PACKET,
110 		    "wrong packet header length");
111 
112 	err = got_pkt_readlen(&n, lenstr, chattygot);
113 	if (n == 0)
114 		return err;
115 	if (n <= 4)
116 		return got_error_msg(GOT_ERR_BAD_PACKET, "packet too short");
117 	n -= 4;
118 
119 	*datalen = n;
120 	return NULL;
121 }
122 
123 const struct got_error *
124 got_pkt_readpkt(int *outlen, int fd, char *buf, int buflen, int chattygot)
125 {
126 	const struct got_error *err = NULL;
127 	int datalen, i;
128 	ssize_t n;
129 
130 	err = got_pkt_readhdr(&datalen, fd, chattygot);
131 	if (err)
132 		return err;
133 
134 	if (datalen > buflen)
135 		return got_error(GOT_ERR_NO_SPACE);
136 
137 	err = got_pkt_readn(&n, fd, buf, datalen);
138 	if (err)
139 		return err;
140 	if (n != datalen)
141 		return got_error_msg(GOT_ERR_BAD_PACKET, "short packet");
142 
143 	if (chattygot > 1) {
144 		fprintf(stderr, "%s: readpkt: %zd:\t", getprogname(), n);
145 		for (i = 0; i < n; i++) {
146 			if (isprint((unsigned char)buf[i]))
147 				fputc(buf[i], stderr);
148 			else
149 				fprintf(stderr, "[0x%.2x]", buf[i]);
150 		}
151 		fputc('\n', stderr);
152 	}
153 
154 	*outlen = n;
155 	return NULL;
156 }
157 
158 const struct got_error *
159 got_pkt_writepkt(int fd, char *buf, int nbuf, int chattygot)
160 {
161 	char len[5];
162 	int i, ret;
163 	ssize_t w;
164 
165 	ret = snprintf(len, sizeof(len), "%04x", nbuf + 4);
166 	if (ret < 0 || (size_t)ret >= sizeof(len))
167 		return got_error(GOT_ERR_NO_SPACE);
168 	w = write(fd, len, 4);
169 	if (w == -1)
170 		return got_error_from_errno("write");
171 	if (w != 4)
172 		return got_error(GOT_ERR_IO);
173 	w = write(fd, buf, nbuf);
174 	if (w == -1)
175 		return got_error_from_errno("write");
176 	if (w != nbuf)
177 		return got_error(GOT_ERR_IO);
178 	if (chattygot > 1) {
179 		fprintf(stderr, "%s: writepkt: %s:\t", getprogname(), len);
180 		for (i = 0; i < nbuf; i++) {
181 			if (isprint((unsigned char)buf[i]))
182 				fputc(buf[i], stderr);
183 			else
184 				fprintf(stderr, "[0x%.2x]", buf[i]);
185 		}
186 		fputc('\n', stderr);
187 	}
188 	return NULL;
189 }