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-rw-r--r--libc/inet/resolv.c226
1 files changed, 136 insertions, 90 deletions
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index 044059d7d..7ef2fba45 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -762,6 +762,10 @@ int attribute_hidden __dns_lookup(const char *name, int type,
int nscount, char **nsip,
unsigned char **outpacket,
struct resolv_answer *a)
+//FIXME: nscount/nsip are *always* taken from __nameservers and __nameserver[]
+//globals. Locking is busted: __nameserver[] can be freed under us.
+//Fix it by eliminating these params and accessing __nameserver(s)
+//only under lock inside this routine.
{
int i, j, len, fd, pos, rc;
#ifdef USE_SELECT
@@ -2084,20 +2088,44 @@ libc_hidden_def(getnameinfo)
#ifdef L_gethostbyname_r
+/* Bug 671 says:
+ * "uClibc resolver's gethostbyname does not return the requested name
+ * as an alias, but instead returns the canonical name. glibc's
+ * gethostbyname has a similar bug where it returns the requested name
+ * with the search domain name appended (to make a FQDN) as an alias,
+ * but not the original name itself. Both contradict POSIX, which says
+ * that the name argument passed to gethostbyname must be in the alias list"
+ * This is fixed now, and we differ from glibc:
+ *
+ * $ ./gethostbyname_uclibc wer.google.com
+ * h_name:'c13-ss-2-lb.cnet.com'
+ * h_length:4
+ * h_addrtype:2 AF_INET
+ * alias:'wer.google.com' <===
+ * addr: 0x4174efd8 '216.239.116.65'
+ *
+ * $ ./gethostbyname_glibc wer.google.com
+ * h_name:'c13-ss-2-lb.cnet.com'
+ * h_length:4
+ * h_addrtype:2 AF_INET
+ * alias:'wer.google.com.com' <===
+ * addr:'216.239.116.65'
+ *
+ * When examples were run, /etc/resolv.conf contained "search com" line.
+ */
int gethostbyname_r(const char * name,
- struct hostent * result_buf,
- char * buf, size_t buflen,
- struct hostent ** result,
- int * h_errnop)
+ struct hostent * result_buf,
+ char * buf,
+ size_t buflen,
+ struct hostent ** result,
+ int * h_errnop)
{
- struct in_addr *in;
struct in_addr **addr_list;
char **alias;
+ char *alias0;
unsigned char *packet;
struct resolv_answer a;
int i;
- int __nameserversXX;
- char ** __nameserverXX;
*result = NULL;
if (!name)
@@ -2128,122 +2156,140 @@ int gethostbyname_r(const char * name,
DPRINTF("Nothing found in /etc/hosts\n");
- /* make sure user char * is aligned */
- i = ALIGN_BUFFER_OFFSET(buf);
- if (unlikely(i)) {
- if (buflen < i)
- return ERANGE;
- buf += i;
- buflen -= i;
- }
-
*h_errnop = NETDB_INTERNAL;
- if (buflen < sizeof(*in))
- return ERANGE;
- in = (struct in_addr*)buf;
- buf += sizeof(*in);
- buflen -= sizeof(*in);
- if (buflen < sizeof(*addr_list)*2)
+ /* prepare future h_aliases[0] */
+ i = strlen(name) + 1;
+ if ((ssize_t)buflen <= i)
return ERANGE;
- addr_list = (struct in_addr**)buf;
- buf += sizeof(*addr_list)*2;
- buflen -= sizeof(*addr_list)*2;
+ strcpy(buf, name);
+ alias0 = buf;
+ buf += i;
+ buflen -= i;
- addr_list[0] = in;
- addr_list[1] = 0;
+ /* make sure pointer is aligned */
+ i = ALIGN_BUFFER_OFFSET(buf);
+ buf += i;
+ buflen -= i;
- if (buflen < sizeof(char *)*ALIAS_DIM)
- return ERANGE;
alias = (char **)buf;
- buf += sizeof(char **)*ALIAS_DIM;
- buflen -= sizeof(char **)*ALIAS_DIM;
+ buf += sizeof(alias[0]) * 2;
+ buflen -= sizeof(alias[0]) * 2;
- if (buflen < 256)
+ addr_list = (struct in_addr **)buf;
+
+ /* do not use *buf or buflen before this verification! */
+ /* buflen may be < 0, must do signed compare */
+ if ((ssize_t)buflen < 256)
return ERANGE;
- strncpy(buf, name, buflen);
- alias[0] = buf;
+ /* we store only one "alias" - the name itself */
+#ifdef __UCLIBC_MJN3_ONLY__
+#warning TODO -- generate the full list
+#endif
+ alias[0] = alias0;
alias[1] = NULL;
- /* First check if this is already an address */
- if (inet_aton(name, in)) {
- result_buf->h_name = buf;
- result_buf->h_addrtype = AF_INET;
- result_buf->h_length = sizeof(*in);
- result_buf->h_addr_list = (char **) addr_list;
- result_buf->h_aliases = alias;
- *result = result_buf;
- *h_errnop = NETDB_SUCCESS;
- return NETDB_SUCCESS;
+ /* maybe it is already an address? */
+ {
+ struct in_addr *in = (struct in_addr *)(buf + sizeof(addr_list[0]) * 2);
+ if (inet_aton(name, in)) {
+ addr_list[0] = in;
+ addr_list[1] = NULL;
+ result_buf->h_name = alias0;
+ result_buf->h_aliases = alias;
+ result_buf->h_addrtype = AF_INET;
+ result_buf->h_length = sizeof(struct in_addr);
+ result_buf->h_addr_list = (char **) addr_list;
+ *result = result_buf;
+ *h_errnop = NETDB_SUCCESS;
+ return NETDB_SUCCESS;
+ }
}
+ /* talk to DNS servers */
__open_nameservers();
-
- /*for (;;)*/ {
-//FIXME: why was it a loop? It never loops...
+ {
+ int __nameserversXX;
+ char ** __nameserverXX;
__UCLIBC_MUTEX_LOCK(__resolv_lock);
__nameserversXX = __nameservers;
__nameserverXX = __nameserver;
__UCLIBC_MUTEX_UNLOCK(__resolv_lock);
a.buf = buf;
- a.buflen = buflen;
+ /* take into account that at least one address will be there,
+ * we'll need space of one in_addr + two addr_list[] elems */
+ a.buflen = buflen - ((sizeof(addr_list[0]) * 2 + sizeof(struct in_addr)));
a.add_count = 0;
i = __dns_lookup(name, T_A, __nameserversXX, __nameserverXX, &packet, &a);
-
if (i < 0) {
*h_errnop = HOST_NOT_FOUND;
- DPRINTF("__dns_lookup\n");
+ DPRINTF("__dns_lookup returned < 0\n");
return TRY_AGAIN;
}
+ }
- if ((a.rdlength + sizeof(struct in_addr*)) * a.add_count + 256 > buflen) {
- free(a.dotted);
- free(packet);
- *h_errnop = NETDB_INTERNAL;
+ if (a.atype == T_A) { /* ADDRESS */
+ /* we need space for addr_list[] and one IPv4 address */
+ /* + 1 accounting for 1st addr (it's in a.rdata),
+ * another + 1 for NULL in last addr_list[]: */
+ int need_bytes = sizeof(addr_list[0]) * (a.add_count + 1 + 1)
+ /* for 1st addr (it's in a.rdata): */
+ + sizeof(struct in_addr);
+ /* how many bytes will 2nd and following addresses take? */
+ int ips_len = a.add_count * a.rdlength;
+
+ buflen -= (need_bytes + ips_len);
+ if ((ssize_t)buflen < 0) {
DPRINTF("buffer too small for all addresses\n");
- return ERANGE;
+ /* *h_errnop = NETDB_INTERNAL; - already is */
+ i = ERANGE;
+ goto free_and_ret;
}
- if (a.add_count > 0) {
- memmove(buf - sizeof(struct in_addr*)*2, buf, a.add_count * a.rdlength);
- addr_list = (struct in_addr**)(buf + a.add_count * a.rdlength);
- addr_list[0] = in;
- for (i = a.add_count - 1; i >= 0; --i)
- addr_list[i+1] = (struct in_addr*)(buf - sizeof(struct in_addr*)*2 + a.rdlength * i);
- addr_list[a.add_count + 1] = 0;
- buflen -= (((char*)&(addr_list[a.add_count + 2])) - buf);
- buf = (char*)&addr_list[a.add_count + 2];
- }
+ /* if there are additional addresses in buf,
+ * move them forward so that they are not destroyed */
+ DPRINTF("a.add_count:%d a.rdlength:%d a.rdata:%p\n", a.add_count, a.rdlength, a.rdata);
+ memmove(buf + need_bytes, buf, ips_len);
- strncpy(buf, a.dotted, buflen);
- free(a.dotted);
+ /* 1st address is in a.rdata, insert it */
+ buf += need_bytes - sizeof(struct in_addr);
+ memcpy(buf, a.rdata, sizeof(struct in_addr));
- if (a.atype == T_A) { /* ADDRESS */
- memcpy(in, a.rdata, sizeof(*in));
- result_buf->h_name = buf;
- result_buf->h_addrtype = AF_INET;
- result_buf->h_length = sizeof(*in);
- result_buf->h_addr_list = (char **) addr_list;
-#ifdef __UCLIBC_MJN3_ONLY__
-#warning TODO -- generate the full list
-#endif
- result_buf->h_aliases = alias; /* TODO: generate the full list */
- free(packet);
- /*was: break;*/
- *result = result_buf;
- *h_errnop = NETDB_SUCCESS;
- return NETDB_SUCCESS;
+ /* fill addr_list[] */
+ for (i = 0; i <= a.add_count; i++) {
+ addr_list[i] = (struct in_addr*)buf;
+ buf += sizeof(struct in_addr);
}
- free(packet);
- *h_errnop = HOST_NOT_FOUND;
- return TRY_AGAIN;
+ addr_list[i] = NULL;
+
+ /* if we have enough space, we can report "better" name
+ * (it may contain search domains attached by __dns_lookup,
+ * or CNAME of the host if it is different from the name
+ * we used to find it) */
+ if (a.dotted && buflen > strlen(a.dotted)) {
+ strcpy(buf, a.dotted);
+ alias0 = buf;
+ }
+
+ result_buf->h_name = alias0;
+ result_buf->h_aliases = alias;
+ result_buf->h_addrtype = AF_INET;
+ result_buf->h_length = sizeof(struct in_addr);
+ result_buf->h_addr_list = (char **) addr_list;
+ *result = result_buf;
+ *h_errnop = NETDB_SUCCESS;
+ i = NETDB_SUCCESS;
+ goto free_and_ret;
}
-/*
- *result = result_buf;
- *h_errnop = NETDB_SUCCESS;
- return NETDB_SUCCESS;
-*/
+
+ *h_errnop = HOST_NOT_FOUND;
+ i = TRY_AGAIN;
+
+ free_and_ret:
+ free(a.dotted);
+ free(packet);
+ return i;
}
libc_hidden_def(gethostbyname_r)
#endif
generated by cgit v1.2.3 (git 2.46.0) at 2025-11-04 00:52:40 +0000