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authorWaldemar Brodkorb <wbx@uclibc-ng.org>2015-12-22 09:47:56 (GMT)
committerWaldemar Brodkorb <wbx@uclibc-ng.org>2015-12-22 09:47:56 (GMT)
commit6b4bcce3cbb89442f96e2e47a507b5983f27a191 (patch)
tree2be29a17ee6854fcbb45586d3605a3fd78ac8bea /libc
parent6994bbf289dc098d38b27521da3a7431e17736db (diff)
resolv: fix gethostbyname2_r to match gethostbyname_r, fixing bugs with AAAA lookups
The latter half of gethostbyname2_r (doing AAAA queries) is rather dramatically different from the corresponding portion of gethostbyname_r (doing A queries). This leads to problems like calls to getaddrinfo only returning one IPv6 address, even when multiple exist. Seems to be entirely a case of divergent evolution -- a half-decade of fixes for the IPv4 code but no love for IPv6. Until now. ;) DNS behaviour for IPv6 is really no different than for IPv4 -- beyond the difference in address sizes, there's no need for the functions to be so different. Consequently, this patch really is almost just a cut-and-paste of gethostbyname_r, with the appropriate substitutions of in6_addr, AF_INET6, etc; while holding on to the few extra bits that actually belong in there (eg #ifdef __UCLIBC_HAS_IPV6__). Signed-off-by: Wes Campaigne <westacular@gmail.com>
Diffstat (limited to 'libc')
-rw-r--r--libc/inet/resolv.c163
1 files changed, 104 insertions, 59 deletions
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index de038e4..3851b2a 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -2200,12 +2200,13 @@ int gethostbyname2_r(const char *name,
? gethostbyname_r(name, result_buf, buf, buflen, result, h_errnop)
: HOST_NOT_FOUND;
#else
- struct in6_addr *in;
struct in6_addr **addr_list;
+ char **alias;
+ char *alias0;
unsigned char *packet;
struct resolv_answer a;
int i;
- int nest = 0;
+ int packet_len;
int wrong_af = 0;
if (family == AF_INET)
@@ -2220,9 +2221,8 @@ int gethostbyname2_r(const char *name,
/* do /etc/hosts first */
{
- int old_errno = errno; /* Save the old errno and reset errno */
- __set_errno(0); /* to check for missing /etc/hosts. */
-
+ int old_errno = errno; /* save the old errno and reset errno */
+ __set_errno(0); /* to check for missing /etc/hosts. */
i = __get_hosts_byname_r(name, AF_INET6 /*family*/, result_buf,
buf, buflen, result, h_errnop);
if (i == NETDB_SUCCESS) {
@@ -2244,42 +2244,58 @@ int gethostbyname2_r(const char *name,
}
__set_errno(old_errno);
}
+
DPRINTF("Nothing found in /etc/hosts\n");
*h_errnop = NETDB_INTERNAL;
+ /* prepare future h_aliases[0] */
+ i = strlen(name) + 1;
+ if ((ssize_t)buflen <= i)
+ return ERANGE;
+ memcpy(buf, name, i); /* paranoia: name might change */
+ alias0 = buf;
+ buf += i;
+ buflen -= i;
/* make sure pointer is aligned */
i = ALIGN_BUFFER_OFFSET(buf);
buf += i;
buflen -= i;
/* Layout in buf:
- * struct in6_addr* in;
- * struct in6_addr* addr_list[2];
- * char scratch_buf[256];
+ * char *alias[2];
+ * struct in6_addr* addr_list[NN+1];
+ * struct in6_addr* in[NN];
*/
- in = (struct in6_addr*)buf;
- buf += sizeof(*in);
- buflen -= sizeof(*in);
- addr_list = (struct in6_addr**)buf;
- buf += sizeof(*addr_list) * 2;
- buflen -= sizeof(*addr_list) * 2;
+ alias = (char **)buf;
+ buf += sizeof(alias[0]) * 2;
+ buflen -= sizeof(alias[0]) * 2;
+ addr_list = (struct in6_addr **)buf;
+ /* buflen may be < 0, must do signed compare */
if ((ssize_t)buflen < 256)
return ERANGE;
- addr_list[0] = in;
- addr_list[1] = NULL;
- strncpy(buf, name, buflen);
- buf[buflen] = '\0';
+
+ /* 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;
/* maybe it is already an address? */
- if (inet_pton(AF_INET6, name, in)) {
- result_buf->h_name = buf;
- result_buf->h_addrtype = AF_INET6;
- result_buf->h_length = sizeof(*in);
- result_buf->h_addr_list = (char **) addr_list;
- /* result_buf->h_aliases = ??? */
- *result = result_buf;
- *h_errnop = NETDB_SUCCESS;
- return NETDB_SUCCESS;
+ {
+ struct in6_addr *in = (struct in6_addr *)(buf + sizeof(addr_list[0]) * 2);
+ if (inet_pton(AF_INET6, 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_INET6;
+ result_buf->h_length = sizeof(struct in6_addr);
+ result_buf->h_addr_list = (char **) addr_list;
+ *result = result_buf;
+ *h_errnop = NETDB_SUCCESS;
+ return NETDB_SUCCESS;
+ }
}
/* what if /etc/hosts has it but it's not IPv6?
@@ -2291,51 +2307,80 @@ int gethostbyname2_r(const char *name,
}
/* talk to DNS servers */
-/* TODO: why it's so different from gethostbyname_r (IPv4 case)? */
- memset(&a, '\0', sizeof(a));
- for (;;) {
- int packet_len;
+ a.buf = buf;
+ /* take into account that at least one address will be there,
+ * we'll need space of one in6_addr + two addr_list[] elems */
+ a.buflen = buflen - ((sizeof(addr_list[0]) * 2 + sizeof(struct in6_addr)));
+ a.add_count = 0;
+ packet_len = __dns_lookup(name, T_AAAA, &packet, &a);
+ if (packet_len < 0) {
+ *h_errnop = HOST_NOT_FOUND;
+ DPRINTF("__dns_lookup returned < 0\n");
+ return TRY_AGAIN;
+ }
-/* Hmm why we memset(a) to zeros only once? */
- packet_len = __dns_lookup(buf, T_AAAA, &packet, &a);
- if (packet_len < 0) {
- *h_errnop = HOST_NOT_FOUND;
- return TRY_AGAIN;
+ if (a.atype == T_AAAA) { /* ADDRESS */
+ /* we need space for addr_list[] and one IPv6 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 in6_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");
+ /* *h_errnop = NETDB_INTERNAL; - already is */
+ i = ERANGE;
+ goto free_and_ret;
}
- strncpy(buf, a.dotted, buflen);
- free(a.dotted);
- if (a.atype != T_CNAME)
- break;
+ /* 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);
- DPRINTF("Got a CNAME in gethostbyname()\n");
- if (++nest > MAX_RECURSE) {
- *h_errnop = NO_RECOVERY;
- return -1;
+ /* 1st address is in a.rdata, insert it */
+ buf += need_bytes - sizeof(struct in6_addr);
+ memcpy(buf, a.rdata, sizeof(struct in6_addr));
+
+ /* fill addr_list[] */
+ for (i = 0; i <= a.add_count; i++) {
+ addr_list[i] = (struct in6_addr*)buf;
+ buf += sizeof(struct in6_addr);
}
- i = __decode_dotted(packet, a.rdoffset, packet_len, buf, buflen);
- free(packet);
- if (i < 0) {
- *h_errnop = NO_RECOVERY;
- return -1;
+ 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;
}
- }
- if (a.atype == T_AAAA) { /* ADDRESS */
- memcpy(in, a.rdata, sizeof(*in));
- result_buf->h_name = buf;
+
+ result_buf->h_name = alias0;
+ result_buf->h_aliases = alias;
result_buf->h_addrtype = AF_INET6;
- result_buf->h_length = sizeof(*in);
+ result_buf->h_length = sizeof(struct in6_addr);
result_buf->h_addr_list = (char **) addr_list;
- /* result_buf->h_aliases = ??? */
- free(packet);
*result = result_buf;
*h_errnop = NETDB_SUCCESS;
- return NETDB_SUCCESS;
+ i = NETDB_SUCCESS;
+ goto free_and_ret;
}
- free(packet);
+
*h_errnop = HOST_NOT_FOUND;
- return TRY_AGAIN;
+ __set_h_errno(HOST_NOT_FOUND);
+ i = TRY_AGAIN;
+ free_and_ret:
+ free(a.dotted);
+ free(packet);
+ return i;
#endif /* __UCLIBC_HAS_IPV6__ */
}
libc_hidden_def(gethostbyname2_r)