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 
27 const struct got_error *
28 got_pkt_readn(ssize_t *off, int fd, void *buf, size_t n)
29 {
30 	ssize_t r;
31 
32 	*off = 0;
33 	while (*off != n) {
34 		r = read(fd, buf + *off, n - *off);
35 		if (r == -1)
36 			return got_error_from_errno("read");
37 		if (r == 0)
38 			return NULL;
39 		*off += r;
40 	}
41 	return NULL;
42 }
43 
44 const struct got_error *
45 got_pkt_flushpkt(int fd, int chattygot)
46 {
47 	ssize_t w;
48 
49 	if (chattygot > 1)
50 		fprintf(stderr, "%s: writepkt: 0000\n", getprogname());
51 
52 	w = write(fd, "0000", 4);
53 	if (w == -1)
54 		return got_error_from_errno("write");
55 	if (w != 4)
56 		return got_error(GOT_ERR_IO);
57 	return NULL;
58 }
59 
60 /*
61  * Packet header contains a 4-byte hexstring which specifies the length
62  * of data which follows.
63  */
64 const struct got_error *
65 got_pkt_readhdr(int *datalen, int fd, int chattygot)
66 {
67 	static const struct got_error *err = NULL;
68 	char lenstr[5];
69 	long len;
70 	char *e;
71 	int n, i;
72 	ssize_t r;
73 
74 	*datalen = 0;
75 
76 	err = got_pkt_readn(&r, fd, lenstr, 4);
77 	if (err)
78 		return err;
79 	if (r == 0) {
80 		/* implicit "0000" */
81 		if (chattygot > 1)
82 			fprintf(stderr, "%s: readpkt: 0000\n", getprogname());
83 		return NULL;
84 	}
85 	if (r != 4)
86 		return got_error_msg(GOT_ERR_BAD_PACKET,
87 		    "wrong packet header length");
88 
89 	lenstr[4] = '\0';
90 	for (i = 0; i < 4; i++) {
91 		if (!isprint((unsigned char)lenstr[i]))
92 			return got_error_msg(GOT_ERR_BAD_PACKET,
93 			    "unprintable character in packet length field");
94 	}
95 	for (i = 0; i < 4; i++) {
96 		if (!isxdigit((unsigned char)lenstr[i])) {
97 			if (chattygot)
98 				fprintf(stderr, "%s: bad length: '%s'\n",
99 				    getprogname(), lenstr);
100 			return got_error_msg(GOT_ERR_BAD_PACKET,
101 			    "packet length not specified in hex");
102 		}
103 	}
104 	errno = 0;
105 	len = strtol(lenstr, &e, 16);
106 	if (lenstr[0] == '\0' || *e != '\0')
107 		return got_error(GOT_ERR_BAD_PACKET);
108 	if (errno == ERANGE && (len == LONG_MAX || len == LONG_MIN))
109 		return got_error_msg(GOT_ERR_BAD_PACKET, "bad packet length");
110 	if (len > INT_MAX || len < INT_MIN)
111 		return got_error_msg(GOT_ERR_BAD_PACKET, "bad packet length");
112 	n = len;
113 	if (n == 0)
114 		return NULL;
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(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;
163 	ssize_t w;
164 
165 	if (snprintf(len, sizeof(len), "%04x", nbuf + 4) >= sizeof(len))
166 		return got_error(GOT_ERR_NO_SPACE);
167 	w = write(fd, len, 4);
168 	if (w == -1)
169 		return got_error_from_errno("write");
170 	if (w != 4)
171 		return got_error(GOT_ERR_IO);
172 	w = write(fd, buf, nbuf);
173 	if (w == -1)
174 		return got_error_from_errno("write");
175 	if (w != nbuf)
176 		return got_error(GOT_ERR_IO);
177 	if (chattygot > 1) {
178 		fprintf(stderr, "%s: writepkt: %s:\t", getprogname(), len);
179 		for (i = 0; i < nbuf; i++) {
180 			if (isprint(buf[i]))
181 				fputc(buf[i], stderr);
182 			else
183 				fprintf(stderr, "[0x%.2x]", buf[i]);
184 		}
185 		fputc('\n', stderr);
186 	}
187 	return NULL;
188 }