lib/pkt.c

   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 }