mirror of
https://github.com/jart/cosmopolitan.git
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5144c22189
- Use nullness checks when calling weakly linked functions. - Avoid typedef for reasons described in Linux Kernel style guide. - Avoid enum in in Windows headers. Earlier in Cosmo's history all one hundred files in libc/nt/enum/ used to be enums and it resulted in gigabytes of DWARF data almost as large as everything else in the codebase combined. - Bitfields aren't our friends. They have frequent ABI breakages, inconsistent arithmetic across compilers, and different endianness between cpus. Compiler authors also haven't invested much roi into making bit fields go fast so they produce poor assembly. - Use memccpy() instead of strncpy() or snprintf() for length-bounded copying of C strings. strncpy() is a misunderstood function and snprintf() is awesome but memccpy() deserves more love.
53 lines
2.8 KiB
C
53 lines
2.8 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 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/alg/alg.h"
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#include "libc/bits/bits.h"
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#include "libc/dns/consts.h"
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#include "libc/dns/dns.h"
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#include "libc/dns/hoststxt.h"
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#include "libc/fmt/fmt.h"
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#include "libc/sock/sock.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/af.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Finds name associated with address in HOSTS.TXT table.
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*
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* @param ht can be GetHostsTxt()
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* @param af can be AF_INET
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* @param ip is IP address in binary (sin_addr)
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* @param buf is buffer to store the name
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* @param bufsize is length of buf
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* @return 1 if found, 0 if not found, or -1 w/ errno
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* @error EAFNOSUPPORT
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*/
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int ResolveHostsReverse(const struct HostsTxt *ht, int af, const uint8_t *ip,
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char *buf, size_t bufsize) {
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size_t i;
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if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
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for (i = 0; i < ht->entries.i; ++i) {
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if (READ32LE(ip) == READ32LE(ht->entries.p[i].ip)) {
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if (memccpy(buf, ht->strings.p + ht->entries.p[i].name, '\0', bufsize)) {
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return 1;
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}
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}
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}
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return 0;
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}
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