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Diffstat (limited to 'libc/dns/net/hosts_cache.c')
-rw-r--r--libc/dns/net/hosts_cache.c524
1 files changed, 524 insertions, 0 deletions
diff --git a/libc/dns/net/hosts_cache.c b/libc/dns/net/hosts_cache.c
new file mode 100644
index 0000000..deafb78
--- /dev/null
+++ b/libc/dns/net/hosts_cache.c
@@ -0,0 +1,524 @@
+/*
+ * Copyright (C) 2016 The CyanogenMod Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <fcntl.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <strings.h>
+#include <sys/file.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <utime.h>
+#include <pthread.h>
+
+#include <netinet/in6.h>
+#include <arpa/inet.h>
+
+#include "hostent.h"
+#include "resolv_private.h"
+
+#define MAX_ADDRLEN (INET6_ADDRSTRLEN - (1 + 5))
+#define MAX_HOSTLEN MAXHOSTNAMELEN
+
+#define ESTIMATED_LINELEN 32
+#define HCFILE_ALLOC_SIZE 256
+
+/* From sethostent.c */
+#define ALIGNBYTES (sizeof(uintptr_t) - 1)
+#define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) &~ ALIGNBYTES)
+
+/*
+ * Host cache entry for hcfile.c_data.
+ * Offsets are into hcfile.h_data.
+ * Strings are *not* terminated by NULL, but by whitespace (isspace) or '#'.
+ * Use hstr* functions with these.
+ */
+struct hcent
+{
+ uint32_t addr;
+ uint32_t name;
+};
+
+/*
+ * Overall host cache file state.
+ */
+struct hcfile
+{
+ int h_fd;
+ struct stat h_st;
+ char *h_data;
+
+ uint32_t c_alloc;
+ uint32_t c_len;
+ struct hcent *c_data;
+};
+static struct hcfile hcfile;
+static pthread_mutex_t hclock = PTHREAD_MUTEX_INITIALIZER;
+
+static size_t hstrlen(const char *s)
+{
+ const char *p = s;
+ while (*p && *p != '#' && !isspace(*p))
+ ++p;
+ return p - s;
+}
+
+static int hstrcmp(const char *a, const char *b)
+{
+ size_t alen = hstrlen(a);
+ size_t blen = hstrlen(b);
+ int res = strncmp(a, b, MIN(alen, blen));
+ if (res == 0)
+ res = alen - blen;
+ return res;
+}
+
+static char *hstrcpy(char *dest, const char *src)
+{
+ size_t len = hstrlen(src);
+ memcpy(dest, src, len);
+ dest[len] = '\0';
+ return dest;
+}
+
+static char *hstrdup(const char *s)
+{
+ size_t len = hstrlen(s);
+ char *dest = (char *)malloc(len + 1);
+ if (!dest)
+ return NULL;
+ memcpy(dest, s, len);
+ dest[len] = '\0';
+ return dest;
+}
+
+static int cmp_hcent_name(const void *a, const void *b)
+{
+ struct hcent *ea = (struct hcent *)a;
+ const char *na = hcfile.h_data + ea->name;
+ struct hcent *eb = (struct hcent *)b;
+ const char *nb = hcfile.h_data + eb->name;
+
+ return hstrcmp(na, nb);
+}
+
+static struct hcent *_hcfindname(const char *name)
+{
+ size_t first, last, mid;
+ struct hcent *cur = NULL;
+ int cmp;
+
+ if (hcfile.c_len == 0)
+ return NULL;
+
+ first = 0;
+ last = hcfile.c_len - 1;
+ mid = (first + last) / 2;
+ while (first <= last) {
+ cur = hcfile.c_data + mid;
+ cmp = hstrcmp(hcfile.h_data + cur->name, name);
+ if (cmp == 0)
+ goto found;
+ if (cmp < 0)
+ first = mid + 1;
+ else {
+ if (mid > 0)
+ last = mid - 1;
+ else
+ return NULL;
+ }
+ mid = (first + last) / 2;
+ }
+ return NULL;
+
+found:
+ while (cur > hcfile.c_data) {
+ struct hcent *prev = cur - 1;
+ cmp = cmp_hcent_name(cur, prev);
+ if (cmp)
+ break;
+ cur = prev;
+ }
+
+ return cur;
+}
+
+/*
+ * Find next name on line, if any.
+ *
+ * Assumes that line is terminated by LF.
+ */
+static const char *_hcnextname(const char *name)
+{
+ while (!isspace(*name)) {
+ if (*name == '#')
+ return NULL;
+ ++name;
+ }
+ while (isspace(*name)) {
+ if (*name == '\n')
+ return NULL;
+ ++name;
+ }
+ if (*name == '#')
+ return NULL;
+ return name;
+}
+
+static int _hcfilemmap(void)
+{
+ struct stat st;
+ int h_fd;
+ char *h_addr;
+ const char *p, *pend;
+ uint32_t c_alloc;
+
+ h_fd = open(_PATH_HOSTS, O_RDONLY);
+ if (h_fd < 0)
+ return -1;
+ if (flock(h_fd, LOCK_EX) != 0) {
+ close(h_fd);
+ return -1;
+ }
+
+ if (hcfile.h_data) {
+ memset(&st, 0, sizeof(st));
+ if (fstat(h_fd, &st) == 0) {
+ if (st.st_size == hcfile.h_st.st_size &&
+ st.st_mtime == hcfile.h_st.st_mtime) {
+ flock(h_fd, LOCK_UN);
+ close(h_fd);
+ return 0;
+ }
+ }
+ free(hcfile.c_data);
+ munmap(hcfile.h_data, hcfile.h_st.st_size);
+ close(hcfile.h_fd);
+ memset(&hcfile, 0, sizeof(struct hcfile));
+ }
+
+ if (fstat(h_fd, &st) != 0) {
+ flock(h_fd, LOCK_UN);
+ close(h_fd);
+ return -1;
+ }
+ h_addr = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED, h_fd, 0);
+ if (h_addr == MAP_FAILED) {
+ flock(h_fd, LOCK_UN);
+ close(h_fd);
+ return -1;
+ }
+
+ hcfile.h_fd = h_fd;
+ hcfile.h_st = st;
+ hcfile.h_data = h_addr;
+
+ c_alloc = 0;
+ /*
+ * Do an initial allocation if the file is "large". Estimate
+ * 32 bytes per line and define "large" as more than half of
+ * the alloc growth size (256 entries).
+ */
+ if (st.st_size >= ESTIMATED_LINELEN * HCFILE_ALLOC_SIZE / 2) {
+ c_alloc = st.st_size / ESTIMATED_LINELEN;
+ hcfile.c_data = malloc(c_alloc * sizeof(struct hcent));
+ if (!hcfile.c_data) {
+ goto oom;
+ }
+ }
+
+ p = (const char *)h_addr;
+ pend = p + st.st_size;
+ while (p < pend) {
+ const char *eol, *addr, *name;
+ size_t len;
+ addr = p;
+ eol = memchr(p, '\n', pend - p);
+ if (!eol)
+ break;
+ p = eol + 1;
+ if (*addr == '#' || *addr == '\n')
+ continue;
+ len = hstrlen(addr);
+ if (len > MAX_ADDRLEN)
+ continue;
+ name = addr + len;
+ while (name < eol && isspace(*name))
+ ++name;
+ while (name < eol) {
+ len = hstrlen(name);
+ if (len == 0)
+ break;
+ if (len < MAX_HOSTLEN) {
+ struct hcent *ent;
+ if (c_alloc <= hcfile.c_len) {
+ struct hcent *c_data;
+ c_alloc += HCFILE_ALLOC_SIZE;
+ c_data = realloc(hcfile.c_data, c_alloc * sizeof(struct hcent));
+ if (!c_data) {
+ goto oom;
+ }
+ hcfile.c_data = c_data;
+ }
+ ent = hcfile.c_data + hcfile.c_len;
+ ent->addr = addr - h_addr;
+ ent->name = name - h_addr;
+ ++hcfile.c_len;
+ }
+ name += len;
+ while (name < eol && isspace(*name))
+ ++name;
+ }
+ }
+
+ qsort(hcfile.c_data, hcfile.c_len,
+ sizeof(struct hcent), cmp_hcent_name);
+
+ flock(h_fd, LOCK_UN);
+
+ return 0;
+
+oom:
+ free(hcfile.c_data);
+ munmap(hcfile.h_data, hcfile.h_st.st_size);
+ flock(hcfile.h_fd, LOCK_UN);
+ close(hcfile.h_fd);
+ memset(&hcfile, 0, sizeof(struct hcfile));
+ return -1;
+}
+
+/*
+ * Caching version of getaddrinfo.
+ *
+ * If we find the requested host name in the cache, use getaddrinfo to
+ * populate the result for each address we find.
+ *
+ * Note glibc and bionic differ in the handling of ai_canonname. POSIX
+ * says that ai_canonname is only populated in the first result entry.
+ * glibc does this. bionic populates ai_canonname in all result entries.
+ * We choose the POSIX/glibc way here.
+ */
+int hc_getaddrinfo(const char *host, const char *service,
+ const struct addrinfo *hints,
+ struct addrinfo **result)
+{
+ int ret = 0;
+ struct hcent *ent, *cur;
+ struct addrinfo *ai;
+ struct addrinfo rhints;
+ struct addrinfo *last;
+ int canonname = 0;
+ int cmp;
+
+ if (getenv("ANDROID_HOSTS_CACHE_DISABLE") != NULL)
+ return EAI_SYSTEM;
+
+ /* Avoid needless work and recursion */
+ if (hints && (hints->ai_flags & AI_NUMERICHOST))
+ return EAI_SYSTEM;
+ if (!host)
+ return EAI_SYSTEM;
+
+ pthread_mutex_lock(&hclock);
+
+ if (_hcfilemmap() != 0) {
+ ret = EAI_SYSTEM;
+ goto out;
+ }
+ ent = _hcfindname(host);
+ if (!ent) {
+ ret = EAI_NONAME;
+ goto out;
+ }
+
+ if (hints) {
+ canonname = (hints->ai_flags & AI_CANONNAME);
+ memcpy(&rhints, hints, sizeof(rhints));
+ rhints.ai_flags &= ~AI_CANONNAME;
+ }
+ else {
+ memset(&rhints, 0, sizeof(rhints));
+ }
+ rhints.ai_flags |= AI_NUMERICHOST;
+
+ last = NULL;
+ cur = ent;
+ do {
+ char addrstr[MAX_ADDRLEN];
+ struct addrinfo *res;
+
+ hstrcpy(addrstr, hcfile.h_data + cur->addr);
+
+ if (getaddrinfo(addrstr, service, &rhints, &res) == 0) {
+ if (!last)
+ (*result)->ai_next = res;
+ else
+ last->ai_next = res;
+ last = res;
+ while (last->ai_next)
+ last = last->ai_next;
+ }
+
+ if(cur + 1 >= hcfile.c_data + hcfile.c_len)
+ break;
+ cmp = cmp_hcent_name(cur, cur + 1);
+ cur = cur + 1;
+ }
+ while (!cmp);
+
+ if (last == NULL) {
+ /* This check is equivalent to (*result)->ai_next == NULL */
+ ret = EAI_NODATA;
+ goto out;
+ }
+
+ if (canonname) {
+ ai = (*result)->ai_next;
+ free(ai->ai_canonname);
+ ai->ai_canonname = hstrdup(hcfile.h_data + ent->name);
+ }
+
+out:
+ pthread_mutex_unlock(&hclock);
+ return ret;
+}
+
+/*
+ * Caching version of gethtbyname.
+ *
+ * Note glibc and bionic differ in the handling of aliases. glibc returns
+ * all aliases for all entries, regardless of whether they match h_addrtype.
+ * bionic returns only the aliases for the first hosts entry. We return all
+ * aliases for all IPv4 entries.
+ *
+ * Additionally, if an alias is IPv6 and the primary name for an alias also
+ * has an IPv4 entry, glibc will return the IPv4 address(es), but bionic
+ * will not. Neither do we.
+ */
+int hc_gethtbyname(const char *host, int af, struct getnamaddr *info)
+{
+ int ret = NETDB_SUCCESS;
+ struct hcent *ent, *cur;
+ int cmp;
+ size_t addrlen;
+ unsigned int naliases = 0;
+ char *aliases[MAXALIASES];
+ unsigned int naddrs = 0;
+ char *addr_ptrs[MAXADDRS];
+ unsigned int n;
+
+ if (getenv("ANDROID_HOSTS_CACHE_DISABLE") != NULL)
+ return NETDB_INTERNAL;
+
+ switch (af) {
+ case AF_INET: addrlen = NS_INADDRSZ; break;
+ case AF_INET6: addrlen = NS_IN6ADDRSZ; break;
+ default:
+ return NETDB_INTERNAL;
+ }
+
+ pthread_mutex_lock(&hclock);
+
+ if (_hcfilemmap() != 0) {
+ ret = NETDB_INTERNAL;
+ goto out;
+ }
+
+ ent = _hcfindname(host);
+ if (!ent) {
+ ret = HOST_NOT_FOUND;
+ goto out;
+ }
+
+ cur = ent;
+ do {
+ char addr[16];
+ char addrstr[MAX_ADDRLEN];
+ char namestr[MAX_HOSTLEN];
+ const char *name;
+
+ hstrcpy(addrstr, hcfile.h_data + cur->addr);
+ if (inet_pton(af, addrstr, &addr) == 1) {
+ char *aligned;
+ /* First match is considered the official hostname */
+ if (naddrs == 0) {
+ hstrcpy(namestr, hcfile.h_data + cur->name);
+ HENT_SCOPY(info->hp->h_name, namestr, info->buf, info->buflen);
+ }
+ for (name = hcfile.h_data + cur->name; name; name = _hcnextname(name)) {
+ if (!hstrcmp(name, host))
+ continue;
+ hstrcpy(namestr, name);
+ HENT_SCOPY(aliases[naliases], namestr, info->buf, info->buflen);
+ ++naliases;
+ if (naliases >= MAXALIASES)
+ goto nospc;
+ }
+ aligned = (char *)ALIGN(info->buf);
+ if (info->buf != aligned) {
+ if ((ptrdiff_t)info->buflen < (aligned - info->buf))
+ goto nospc;
+ info->buflen -= (aligned - info->buf);
+ info->buf = aligned;
+ }
+ HENT_COPY(addr_ptrs[naddrs], addr, addrlen, info->buf, info->buflen);
+ ++naddrs;
+ if (naddrs >= MAXADDRS)
+ goto nospc;
+ }
+
+ if(cur + 1 >= hcfile.c_data + hcfile.c_len)
+ break;
+ cmp = cmp_hcent_name(cur, cur + 1);
+ cur = cur + 1;
+ }
+ while (!cmp);
+
+ if (naddrs == 0) {
+ ret = HOST_NOT_FOUND;
+ goto out;
+ }
+
+ addr_ptrs[naddrs++] = NULL;
+ aliases[naliases++] = NULL;
+
+ /* hp->h_name already populated */
+ HENT_ARRAY(info->hp->h_aliases, naliases, info->buf, info->buflen);
+ for (n = 0; n < naliases; ++n) {
+ info->hp->h_aliases[n] = aliases[n];
+ }
+ info->hp->h_addrtype = af;
+ info->hp->h_length = addrlen;
+ HENT_ARRAY(info->hp->h_addr_list, naddrs, info->buf, info->buflen);
+ for (n = 0; n < naddrs; ++n) {
+ info->hp->h_addr_list[n] = addr_ptrs[n];
+ }
+
+out:
+ pthread_mutex_unlock(&hclock);
+ *info->he = ret;
+ return ret;
+
+nospc:
+ ret = NETDB_INTERNAL;
+ goto out;
+}
generated by cgit v1.1 at 2024-12-22 09:15:21 +0000