61 lines
2.9 KiB
C
61 lines
2.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/dns/dns.h"
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#include "libc/str/str.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Writes dotted hostname to DNS message wire.
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*
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* The wire format is basically a sequence of Pascal strings, for each
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* label in the name. We only do enough validation to maintain protocol
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* invariants.
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*
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* @param name is a dotted NUL-terminated hostname string
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* @return bytes written (excluding NUL) or -1 w/ errno
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*/
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int pascalifydnsname(uint8_t *buf, size_t size, const char *name) {
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size_t i = 0;
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size_t namelen = strlen(name);
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if (namelen > DNS_NAME_MAX) return enametoolong();
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if (size || namelen) {
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if (namelen + 1 > size) return enospc();
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buf[0] = '\0';
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size_t j = 0;
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for (;;) {
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size_t k;
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for (k = 0; name[j + k] && name[j + k] != '.'; ++k) {
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buf[i + k + 1] = name[j + k];
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}
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if (k) {
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if (k > DNS_LABEL_MAX) return enametoolong();
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buf[i] = k;
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i += k + 1;
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}
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j += k + 1;
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if (!name[j - 1]) {
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break;
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}
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}
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buf[i] = '\0';
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}
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return i;
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}
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