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 #include "got_lib_poll.h"
28 
29 #define GOT_PKT_TIMEOUT	30
30 
31 const struct got_error *
32 got_pkt_readn(ssize_t *off, int fd, void *buf, size_t n)
33 {
34 	const struct got_error *err;
35 	size_t len;
36 
37 	err = got_poll_read_full_timeout(fd, &len, buf, n, n,
38 	    GOT_PKT_TIMEOUT);
39 	if (err)
40 		return err;
41 
42 	/* XXX size_t -> ssize_t */
43 	if (len > SSIZE_MAX)
44 		return got_error(GOT_ERR_RANGE);
45 	*off = len;
46 	return NULL;
47 }
48 
49 const struct got_error *
50 got_pkt_flushpkt(int fd, int chattygot)
51 {
52 	ssize_t w;
53 
54 	if (chattygot > 1)
55 		fprintf(stderr, "%s: writepkt: 0000\n", getprogname());
56 
57 	w = write(fd, "0000", 4);
58 	if (w == -1)
59 		return got_error_from_errno("write");
60 	if (w != 4)
61 		return got_error(GOT_ERR_IO);
62 	return NULL;
63 }
64 
65 const struct got_error *
66 got_pkt_readlen(int *len, const char *str, int chattygot)
67 {
68 	int	 i;
69 
70 	*len = 0;
71 	for (i = 0; i < 4; i++) {
72 		if ('0' <= str[i] && str[i] <= '9') {
73 			*len *= 16;
74 			*len += str[i] - '0';
75 		} else if ('a' <= str[i] && str[i] <= 'f') {
76 			*len *= 16;
77 			*len += str[i] - 'a' + 10;
78 		} else {
79 			if (chattygot)
80 				fprintf(stderr, "%s: bad length: '.4%s'\n",
81 				    getprogname(), str);
82 			return got_error_msg(GOT_ERR_BAD_PACKET,
83 			    "packet length has invalid format");
84 		}
85 	}
86 	return NULL;
87 }
88 
89 /*
90  * Packet header contains a 4-byte hexstring which specifies the length
91  * of data which follows.
92  */
93 const struct got_error *
94 got_pkt_readhdr(int *datalen, int fd, int chattygot)
95 {
96 	static const struct got_error *err;
97 	char lenstr[4];
98 	ssize_t r;
99 	int n;
100 
101 	*datalen = 0;
102 
103 	err = got_pkt_readn(&r, fd, lenstr, 4);
104 	if (err)
105 		return err;
106 	if (r == 0) {
107 		/* implicit "0000" */
108 		if (chattygot > 1)
109 			fprintf(stderr, "%s: readpkt: 0000\n", getprogname());
110 		return NULL;
111 	}
112 	if (r != 4)
113 		return got_error_msg(GOT_ERR_BAD_PACKET,
114 		    "wrong packet header length");
115 
116 	err = got_pkt_readlen(&n, lenstr, chattygot);
117 	if (n == 0)
118 		return err;
119 	if (n <= 4)
120 		return got_error_msg(GOT_ERR_BAD_PACKET, "packet too short");
121 	n -= 4;
122 
123 	*datalen = n;
124 	return NULL;
125 }
126 
127 const struct got_error *
128 got_pkt_readpkt(int *outlen, int fd, char *buf, int buflen, int chattygot)
129 {
130 	const struct got_error *err = NULL;
131 	int datalen, i;
132 	ssize_t n;
133 
134 	err = got_pkt_readhdr(&datalen, fd, chattygot);
135 	if (err)
136 		return err;
137 
138 	if (datalen > buflen)
139 		return got_error(GOT_ERR_NO_SPACE);
140 
141 	err = got_pkt_readn(&n, fd, buf, datalen);
142 	if (err)
143 		return err;
144 	if (n != datalen)
145 		return got_error_msg(GOT_ERR_BAD_PACKET, "short packet");
146 
147 	if (chattygot > 1) {
148 		fprintf(stderr, "%s: readpkt: %zd:\t", getprogname(), n);
149 		for (i = 0; i < n; i++) {
150 			if (isprint((unsigned char)buf[i]))
151 				fputc(buf[i], stderr);
152 			else
153 				fprintf(stderr, "[0x%.2x]", buf[i]);
154 		}
155 		fputc('\n', stderr);
156 	}
157 
158 	*outlen = n;
159 	return NULL;
160 }
161 
162 const struct got_error *
163 got_pkt_writepkt(int fd, char *buf, int nbuf, int chattygot)
164 {
165 	char len[5];
166 	int i, ret;
167 	ssize_t w;
168 
169 	ret = snprintf(len, sizeof(len), "%04x", nbuf + 4);
170 	if (ret < 0 || (size_t)ret >= sizeof(len))
171 		return got_error(GOT_ERR_NO_SPACE);
172 	w = write(fd, len, 4);
173 	if (w == -1)
174 		return got_error_from_errno("write");
175 	if (w != 4)
176 		return got_error(GOT_ERR_IO);
177 	w = write(fd, buf, nbuf);
178 	if (w == -1)
179 		return got_error_from_errno("write");
180 	if (w != nbuf)
181 		return got_error(GOT_ERR_IO);
182 	if (chattygot > 1) {
183 		fprintf(stderr, "%s: writepkt: %s:\t", getprogname(), len);
184 		for (i = 0; i < nbuf; i++) {
185 			if (isprint((unsigned char)buf[i]))
186 				fputc(buf[i], stderr);
187 			else
188 				fprintf(stderr, "[0x%.2x]", buf[i]);
189 		}
190 		fputc('\n', stderr);
191 	}
192 	return NULL;
193 }