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121 lines
3.1 KiB
C
121 lines
3.1 KiB
C
/* Optional inetd plugin for the Character Generator Protocol, RFC 864
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*
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* Copyright (c) 2016 Joachim Nilsson <troglobit@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <arpa/inet.h>
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#include <unistd.h> /* STDIN_FILENO */
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#include <sys/socket.h>
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#include "plugin.h"
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#define NAME "chargen"
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#define PATTERN "!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~ "
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static char *generator(char *buf, size_t buflen)
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{
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size_t num, len, width = 72;
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static size_t pos = 0;
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const char pattern[] = PATTERN;
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if (buflen < width)
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width = buflen;
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len = width;
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if (len + 3 > buflen)
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len = buflen - 3;
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if (pos + len > sizeof(pattern)) {
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num = sizeof(pattern) - pos;
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len -= num;
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} else {
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num = width;
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if (num + 3 > buflen)
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num = buflen - 3;
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len = 0;
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}
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strncpy(buf, &pattern[pos], num--);
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if (len++)
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strncpy(&buf[num], pattern, len);
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strlcat(buf, "\r\n", width);
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if (++pos >= sizeof(pattern) - 1)
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pos = 0;
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return buf;
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}
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static int recv_peer(int sd, char *buf, ssize_t len, struct sockaddr *sa, socklen_t *sa_len)
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{
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len = recvfrom(sd, buf, len, MSG_DONTWAIT, sa, sa_len);
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if (-1 == len)
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return -1; /* On error, close connection. */
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if (inetd_check_loop(sa, *sa_len, NAME))
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return -1;
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return 0;
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}
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static int send_peer(int sd, char *buf, ssize_t len, struct sockaddr *sa, socklen_t sa_len)
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{
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char *pattern = generator(buf, len);
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return sendto(sd, pattern, strlen(pattern), MSG_DONTWAIT, sa, sa_len);
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}
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static int cb(int type)
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{
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int sd = STDIN_FILENO;
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char buf[BUFSIZ];
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struct sockaddr_storage sa;
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socklen_t sa_len = sizeof(sa);
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if (recv_peer(sd, buf, sizeof(buf), (struct sockaddr *)&sa, &sa_len))
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return -1;
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return send_peer(sd, buf, sizeof(buf), (struct sockaddr *)&sa, sa_len);
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}
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static plugin_t plugin = {
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.name = NAME, /* Must match the inetd /etc/services entry */
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.inetd = {
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.cmd = cb
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},
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};
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PLUGIN_INIT(plugin_init)
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{
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plugin_register(&plugin);
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}
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PLUGIN_EXIT(plugin_exit)
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{
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plugin_unregister(&plugin);
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}
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/**
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* Local Variables:
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* indent-tabs-mode: t
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* c-file-style: "linux"
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* End:
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*/
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