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 #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 }