cosmopolitan/libc/dns/gethoststxt.c

80 lines
3.8 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/bits.h"
#include "libc/bits/pushpop.h"
#include "libc/bits/safemacros.h"
#include "libc/dce.h"
#include "libc/dns/hoststxt.h"
#include "libc/fmt/fmt.h"
#include "libc/macros.h"
#include "libc/nt/systeminfo.h"
#include "libc/runtime/runtime.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
static struct HostsTxt *g_hoststxt;
static struct HostsTxtInitialStaticMemory {
struct HostsTxt ht;
struct HostsTxtEntry entries[8];
char strings[64];
} g_hoststxt_init;
static textwindows noinline char *getnthoststxtpath(char *pathbuf,
uint32_t size) {
const char *const kWinHostsPath = "\\drivers\\etc\\hosts";
uint32_t len = GetSystemDirectoryA(&pathbuf[0], size);
if (len && len + strlen(kWinHostsPath) + 1 < size) {
if (pathbuf[len] == '\\') pathbuf[len--] = '\0';
memcpy(&pathbuf[len], kWinHostsPath, strlen(kWinHostsPath) + 1);
return &pathbuf[0];
} else {
return NULL;
}
}
/**
* Returns parsed sorted singleton hardcoded hostname→ip4 map.
*
* @note yoinking realloc() ensures there's no size limits
*/
const struct HostsTxt *gethoststxt(void) {
struct HostsTxtInitialStaticMemory *init = &g_hoststxt_init;
if (!g_hoststxt) {
g_hoststxt = &init->ht;
init->ht.entries.n = pushpop(ARRAYLEN(init->entries));
init->ht.entries.p = init->entries;
init->ht.strings.n = pushpop(ARRAYLEN(init->strings));
init->ht.strings.p = init->strings;
__cxa_atexit(freehoststxt, &g_hoststxt, NULL);
char pathbuf[PATH_MAX];
const char *path = "/etc/hosts";
if (IsWindows()) {
path = firstnonnull(getnthoststxtpath(pathbuf, ARRAYLEN(pathbuf)), path);
}
FILE *f;
if (!(f = fopen(path, "r")) || parsehoststxt(g_hoststxt, f) == -1) {
if (!IsTiny()) fprintf(stderr, "%s: %s: %m\n", "warning", path);
}
fclose(f);
sorthoststxt(g_hoststxt);
}
return g_hoststxt;
}