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 /*
62  * Packet header contains a 4-byte hexstring which specifies the length
63  * of data which follows.
64  */
65 const struct got_error *
66 got_pkt_readhdr(int *datalen, int fd, int chattygot)
67 {
68 	static const struct got_error *err = NULL;
69 	char lenstr[5];
70 	long len;
71 	char *e;
72 	int n, i;
73 	ssize_t r;
74 
75 	*datalen = 0;
76 
77 	err = got_pkt_readn(&r, fd, lenstr, 4);
78 	if (err)
79 		return err;
80 	if (r == 0) {
81 		/* implicit "0000" */
82 		if (chattygot > 1)
83 			fprintf(stderr, "%s: readpkt: 0000\n", getprogname());
84 		return NULL;
85 	}
86 	if (r != 4)
87 		return got_error_msg(GOT_ERR_BAD_PACKET,
88 		    "wrong packet header length");
89 
90 	lenstr[4] = '\0';
91 	for (i = 0; i < 4; i++) {
92 		if (!isprint((unsigned char)lenstr[i]))
93 			return got_error_msg(GOT_ERR_BAD_PACKET,
94 			    "unprintable character in packet length field");
95 	}
96 	for (i = 0; i < 4; i++) {
97 		if (!isxdigit((unsigned char)lenstr[i])) {
98 			if (chattygot)
99 				fprintf(stderr, "%s: bad length: '%s'\n",
100 				    getprogname(), lenstr);
101 			return got_error_msg(GOT_ERR_BAD_PACKET,
102 			    "packet length not specified in hex");
103 		}
104 	}
105 	errno = 0;
106 	len = strtol(lenstr, &e, 16);
107 	if (lenstr[0] == '\0' || *e != '\0')
108 		return got_error(GOT_ERR_BAD_PACKET);
109 	if (errno == ERANGE && (len == LONG_MAX || len == LONG_MIN))
110 		return got_error_msg(GOT_ERR_BAD_PACKET, "bad packet length");
111 	if (len > INT_MAX || len < INT_MIN)
112 		return got_error_msg(GOT_ERR_BAD_PACKET, "bad packet length");
113 	n = len;
114 	if (n == 0)
115 		return NULL;
116 	if (n <= 4)
117 		return got_error_msg(GOT_ERR_BAD_PACKET, "packet too short");
118 	n  -= 4;
119 
120 	*datalen = n;
121 	return NULL;
122 }
123 
124 const struct got_error *
125 got_pkt_readpkt(int *outlen, int fd, char *buf, int buflen, int chattygot)
126 {
127 	const struct got_error *err = NULL;
128 	int datalen, i;
129 	ssize_t n;
130 
131 	err = got_pkt_readhdr(&datalen, fd, chattygot);
132 	if (err)
133 		return err;
134 
135 	if (datalen > buflen)
136 		return got_error(GOT_ERR_NO_SPACE);
137 
138 	err = got_pkt_readn(&n, fd, buf, datalen);
139 	if (err)
140 		return err;
141 	if (n != datalen)
142 		return got_error_msg(GOT_ERR_BAD_PACKET, "short packet");
143 
144 	if (chattygot > 1) {
145 		fprintf(stderr, "%s: readpkt: %zd:\t", getprogname(), n);
146 		for (i = 0; i < n; i++) {
147 			if (isprint((unsigned char)buf[i]))
148 				fputc(buf[i], stderr);
149 			else
150 				fprintf(stderr, "[0x%.2x]", buf[i]);
151 		}
152 		fputc('\n', stderr);
153 	}
154 
155 	*outlen = n;
156 	return NULL;
157 }
158 
159 const struct got_error *
160 got_pkt_writepkt(int fd, char *buf, int nbuf, int chattygot)
161 {
162 	char len[5];
163 	int i, ret;
164 	ssize_t w;
165 
166 	ret = snprintf(len, sizeof(len), "%04x", nbuf + 4);
167 	if (ret < 0 || (size_t)ret >= sizeof(len))
168 		return got_error(GOT_ERR_NO_SPACE);
169 	w = write(fd, len, 4);
170 	if (w == -1)
171 		return got_error_from_errno("write");
172 	if (w != 4)
173 		return got_error(GOT_ERR_IO);
174 	w = write(fd, buf, nbuf);
175 	if (w == -1)
176 		return got_error_from_errno("write");
177 	if (w != nbuf)
178 		return got_error(GOT_ERR_IO);
179 	if (chattygot > 1) {
180 		fprintf(stderr, "%s: writepkt: %s:\t", getprogname(), len);
181 		for (i = 0; i < nbuf; i++) {
182 			if (isprint((unsigned char)buf[i]))
183 				fputc(buf[i], stderr);
184 			else
185 				fprintf(stderr, "[0x%.2x]", buf[i]);
186 		}
187 		fputc('\n', stderr);
188 	}
189 	return NULL;
190 }