commit d9c979abf9307ef3e27dbe65317430977bb322c7
Author: Florian Weimer <fweimer@redhat.com>
Date: Tue Aug 30 10:02:49 2022 +0200
nss_dns: Split getanswer_ptr from getanswer_r
And expand the use of name_ok and qtype in getanswer_ptr (the
former also in getanswer_r).
After further cleanups, not much code will be shared between the
two functions.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit 0dcc43e9981005540bf39dc7bf33fbab62cf9e84)
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
index 6e83fca1c5b1f98c..a6bf73a091968358 100644
--- a/resolv/nss_dns/dns-host.c
+++ b/resolv/nss_dns/dns-host.c
@@ -117,6 +117,11 @@ static enum nss_status getanswer_r (struct resolv_context *ctx,
struct hostent *result, char *buffer,
size_t buflen, int *errnop, int *h_errnop,
int map, int32_t *ttlp, char **canonp);
+static enum nss_status getanswer_ptr (const querybuf *answer, int anslen,
+ const char *qname,
+ struct hostent *result, char *buffer,
+ size_t buflen, int *errnop,
+ int *h_errnop, int32_t *ttlp);
static enum nss_status gaih_getanswer (const querybuf *answer1, int anslen1,
const querybuf *answer2, int anslen2,
@@ -562,9 +567,8 @@ _nss_dns_gethostbyaddr2_r (const void *addr, socklen_t len, int af,
return errno == ECONNREFUSED ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
}
- status = getanswer_r
- (ctx, host_buffer.buf, n, qbuf, T_PTR, result, buffer, buflen,
- errnop, h_errnop, 0 /* XXX */, ttlp, NULL);
+ status = getanswer_ptr (host_buffer.buf, n, qbuf, result,
+ buffer, buflen, errnop, h_errnop, ttlp);
if (host_buffer.buf != orig_host_buffer)
free (host_buffer.buf);
if (status != NSS_STATUS_SUCCESS)
@@ -660,8 +664,6 @@ getanswer_r (struct resolv_context *ctx,
int haveanswer, had_error;
char *bp, **ap, **hap;
char tbuf[MAXDNAME];
- const char *tname;
- int (*name_ok) (const char *);
u_char packtmp[NS_MAXCDNAME];
int have_to_map = 0;
uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
@@ -680,22 +682,8 @@ getanswer_r (struct resolv_context *ctx,
if (buflen - sizeof (struct host_data) != linebuflen)
linebuflen = INT_MAX;
- tname = qname;
result->h_name = NULL;
end_of_message = answer->buf + anslen;
- switch (qtype)
- {
- case T_A:
- case T_AAAA:
- name_ok = __libc_res_hnok;
- break;
- case T_PTR:
- name_ok = __libc_res_dnok;
- break;
- default:
- *errnop = ENOENT;
- return NSS_STATUS_UNAVAIL; /* XXX should be abort(); */
- }
/*
* find first satisfactory answer
@@ -730,7 +718,7 @@ getanswer_r (struct resolv_context *ctx,
*h_errnop = NO_RECOVERY;
return NSS_STATUS_UNAVAIL;
}
- if (__glibc_unlikely (name_ok (bp) == 0))
+ if (__glibc_unlikely (__libc_res_hnok (bp) == 0))
{
errno = EBADMSG;
*errnop = EBADMSG;
@@ -784,7 +772,7 @@ getanswer_r (struct resolv_context *ctx,
n = -1;
}
- if (__glibc_unlikely (n < 0 || (*name_ok) (bp) == 0))
+ if (__glibc_unlikely (n < 0 || __libc_res_hnok (bp) == 0))
{
++had_error;
continue;
@@ -817,7 +805,7 @@ getanswer_r (struct resolv_context *ctx,
continue; /* XXX - had_error++ ? */
}
- if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME)
+ if (type == T_CNAME)
{
/* A CNAME could also have a TTL entry. */
if (ttlp != NULL && ttl < *ttlp)
@@ -827,7 +815,7 @@ getanswer_r (struct resolv_context *ctx,
continue;
n = __libc_dn_expand (answer->buf, end_of_message, cp,
tbuf, sizeof tbuf);
- if (__glibc_unlikely (n < 0 || (*name_ok) (tbuf) == 0))
+ if (__glibc_unlikely (n < 0 || __libc_res_hnok (tbuf) == 0))
{
++had_error;
continue;
@@ -858,7 +846,260 @@ getanswer_r (struct resolv_context *ctx,
continue;
}
- if (qtype == T_PTR && type == T_CNAME)
+ if (type == T_A && qtype == T_AAAA && map)
+ have_to_map = 1;
+ else if (__glibc_unlikely (type != qtype))
+ {
+ cp += n;
+ continue; /* XXX - had_error++ ? */
+ }
+
+ switch (type)
+ {
+ case T_A:
+ case T_AAAA:
+ if (__glibc_unlikely (__strcasecmp (result->h_name, bp) != 0))
+ {
+ cp += n;
+ continue; /* XXX - had_error++ ? */
+ }
+
+ /* Stop parsing at a record whose length is incorrect. */
+ if (n != rrtype_to_rdata_length (type))
+ {
+ ++had_error;
+ break;
+ }
+
+ /* Skip records of the wrong type. */
+ if (n != result->h_length)
+ {
+ cp += n;
+ continue;
+ }
+ if (!haveanswer)
+ {
+ int nn;
+
+ /* We compose a single hostent out of the entire chain of
+ entries, so the TTL of the hostent is essentially the lowest
+ TTL in the chain. */
+ if (ttlp != NULL && ttl < *ttlp)
+ *ttlp = ttl;
+ if (canonp != NULL)
+ *canonp = bp;
+ result->h_name = bp;
+ nn = strlen (bp) + 1; /* for the \0 */
+ bp += nn;
+ linebuflen -= nn;
+ }
+
+ /* Provide sufficient alignment for both address
+ families. */
+ enum { align = 4 };
+ _Static_assert ((align % __alignof__ (struct in_addr)) == 0,
+ "struct in_addr alignment");
+ _Static_assert ((align % __alignof__ (struct in6_addr)) == 0,
+ "struct in6_addr alignment");
+ {
+ char *new_bp = PTR_ALIGN_UP (bp, align);
+ linebuflen -= new_bp - bp;
+ bp = new_bp;
+ }
+
+ if (__glibc_unlikely (n > linebuflen))
+ goto too_small;
+ bp = __mempcpy (*hap++ = bp, cp, n);
+ cp += n;
+ linebuflen -= n;
+ break;
+ default:
+ abort ();
+ }
+ if (had_error == 0)
+ ++haveanswer;
+ }
+
+ if (haveanswer > 0)
+ {
+ *ap = NULL;
+ *hap = NULL;
+ /*
+ * Note: we sort even if host can take only one address
+ * in its return structures - should give it the "best"
+ * address in that case, not some random one
+ */
+ if (haveanswer > 1 && qtype == T_A
+ && __resolv_context_sort_count (ctx) > 0)
+ addrsort (ctx, host_data->h_addr_ptrs, haveanswer);
+
+ if (result->h_name == NULL)
+ {
+ n = strlen (qname) + 1; /* For the \0. */
+ if (n > linebuflen)
+ goto too_small;
+ if (n >= MAXHOSTNAMELEN)
+ goto no_recovery;
+ result->h_name = bp;
+ bp = __mempcpy (bp, qname, n); /* Cannot overflow. */
+ linebuflen -= n;
+ }
+
+ if (have_to_map)
+ if (map_v4v6_hostent (result, &bp, &linebuflen))
+ goto too_small;
+ *h_errnop = NETDB_SUCCESS;
+ return NSS_STATUS_SUCCESS;
+ }
+ no_recovery:
+ *h_errnop = NO_RECOVERY;
+ *errnop = ENOENT;
+ /* Special case here: if the resolver sent a result but it only
+ contains a CNAME while we are looking for a T_A or T_AAAA record,
+ we fail with NOTFOUND instead of TRYAGAIN. */
+ return ((qtype == T_A || qtype == T_AAAA) && ap != host_data->aliases
+ ? NSS_STATUS_NOTFOUND : NSS_STATUS_TRYAGAIN);
+}
+
+static enum nss_status
+getanswer_ptr (const querybuf *answer, int anslen, const char *qname,
+ struct hostent *result, char *buffer, size_t buflen,
+ int *errnop, int *h_errnop, int32_t *ttlp)
+{
+ struct host_data
+ {
+ char *aliases[MAX_NR_ALIASES];
+ unsigned char host_addr[16]; /* IPv4 or IPv6 */
+ char *h_addr_ptrs[0];
+ } *host_data;
+ int linebuflen;
+ const HEADER *hp;
+ const u_char *end_of_message, *cp;
+ int n, ancount, qdcount;
+ int haveanswer, had_error;
+ char *bp, **ap, **hap;
+ char tbuf[MAXDNAME];
+ const char *tname;
+ u_char packtmp[NS_MAXCDNAME];
+ uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
+ buffer += pad;
+ buflen = buflen > pad ? buflen - pad : 0;
+ if (__glibc_unlikely (buflen < sizeof (struct host_data)))
+ {
+ /* The buffer is too small. */
+ too_small:
+ *errnop = ERANGE;
+ *h_errnop = NETDB_INTERNAL;
+ return NSS_STATUS_TRYAGAIN;
+ }
+ host_data = (struct host_data *) buffer;
+ linebuflen = buflen - sizeof (struct host_data);
+ if (buflen - sizeof (struct host_data) != linebuflen)
+ linebuflen = INT_MAX;
+
+ tname = qname;
+ result->h_name = NULL;
+ end_of_message = answer->buf + anslen;
+
+ /*
+ * find first satisfactory answer
+ */
+ hp = &answer->hdr;
+ ancount = ntohs (hp->ancount);
+ qdcount = ntohs (hp->qdcount);
+ cp = answer->buf + HFIXEDSZ;
+ if (__glibc_unlikely (qdcount != 1))
+ {
+ *h_errnop = NO_RECOVERY;
+ return NSS_STATUS_UNAVAIL;
+ }
+ if (sizeof (struct host_data) + (ancount + 1) * sizeof (char *) >= buflen)
+ goto too_small;
+ bp = (char *) &host_data->h_addr_ptrs[ancount + 1];
+ linebuflen -= (ancount + 1) * sizeof (char *);
+
+ n = __ns_name_unpack (answer->buf, end_of_message, cp,
+ packtmp, sizeof packtmp);
+ if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
+ {
+ if (__glibc_unlikely (errno == EMSGSIZE))
+ goto too_small;
+
+ n = -1;
+ }
+
+ if (__glibc_unlikely (n < 0))
+ {
+ *errnop = errno;
+ *h_errnop = NO_RECOVERY;
+ return NSS_STATUS_UNAVAIL;
+ }
+ if (__glibc_unlikely (__libc_res_dnok (bp) == 0))
+ {
+ errno = EBADMSG;
+ *errnop = EBADMSG;
+ *h_errnop = NO_RECOVERY;
+ return NSS_STATUS_UNAVAIL;
+ }
+ cp += n + QFIXEDSZ;
+
+ ap = host_data->aliases;
+ *ap = NULL;
+ result->h_aliases = host_data->aliases;
+ hap = host_data->h_addr_ptrs;
+ *hap = NULL;
+ result->h_addr_list = host_data->h_addr_ptrs;
+ haveanswer = 0;
+ had_error = 0;
+
+ while (ancount-- > 0 && cp < end_of_message && had_error == 0)
+ {
+ int type, class;
+
+ n = __ns_name_unpack (answer->buf, end_of_message, cp,
+ packtmp, sizeof packtmp);
+ if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
+ {
+ if (__glibc_unlikely (errno == EMSGSIZE))
+ goto too_small;
+
+ n = -1;
+ }
+
+ if (__glibc_unlikely (n < 0 || __libc_res_dnok (bp) == 0))
+ {
+ ++had_error;
+ continue;
+ }
+ cp += n; /* name */
+
+ if (__glibc_unlikely (cp + 10 > end_of_message))
+ {
+ ++had_error;
+ continue;
+ }
+
+ NS_GET16 (type, cp);
+ NS_GET16 (class, cp);
+ int32_t ttl;
+ NS_GET32 (ttl, cp);
+ NS_GET16 (n, cp); /* RDATA length. */
+
+ if (end_of_message - cp < n)
+ {
+ /* RDATA extends beyond the end of the packet. */
+ ++had_error;
+ continue;
+ }
+
+ if (__glibc_unlikely (class != C_IN))
+ {
+ /* XXX - debug? syslog? */
+ cp += n;
+ continue; /* XXX - had_error++ ? */
+ }
+
+ if (type == T_CNAME)
{
/* A CNAME could also have a TTL entry. */
if (ttlp != NULL && ttl < *ttlp)
@@ -887,14 +1128,6 @@ getanswer_r (struct resolv_context *ctx,
continue;
}
- if (type == T_A && qtype == T_AAAA && map)
- have_to_map = 1;
- else if (__glibc_unlikely (type != qtype))
- {
- cp += n;
- continue; /* XXX - had_error++ ? */
- }
-
switch (type)
{
case T_PTR:
@@ -956,8 +1189,6 @@ getanswer_r (struct resolv_context *ctx,
TTL in the chain. */
if (ttlp != NULL && ttl < *ttlp)
*ttlp = ttl;
- if (canonp != NULL)
- *canonp = bp;
result->h_name = bp;
nn = strlen (bp) + 1; /* for the \0 */
bp += nn;
@@ -984,7 +1215,8 @@ getanswer_r (struct resolv_context *ctx,
linebuflen -= n;
break;
default:
- abort ();
+ cp += n;
+ continue; /* XXX - had_error++ ? */
}
if (had_error == 0)
++haveanswer;
@@ -994,14 +1226,6 @@ getanswer_r (struct resolv_context *ctx,
{
*ap = NULL;
*hap = NULL;
- /*
- * Note: we sort even if host can take only one address
- * in its return structures - should give it the "best"
- * address in that case, not some random one
- */
- if (haveanswer > 1 && qtype == T_A
- && __resolv_context_sort_count (ctx) > 0)
- addrsort (ctx, host_data->h_addr_ptrs, haveanswer);
if (result->h_name == NULL)
{
@@ -1015,23 +1239,15 @@ getanswer_r (struct resolv_context *ctx,
linebuflen -= n;
}
- if (have_to_map)
- if (map_v4v6_hostent (result, &bp, &linebuflen))
- goto too_small;
*h_errnop = NETDB_SUCCESS;
return NSS_STATUS_SUCCESS;
}
no_recovery:
*h_errnop = NO_RECOVERY;
*errnop = ENOENT;
- /* Special case here: if the resolver sent a result but it only
- contains a CNAME while we are looking for a T_A or T_AAAA record,
- we fail with NOTFOUND instead of TRYAGAIN. */
- return ((qtype == T_A || qtype == T_AAAA) && ap != host_data->aliases
- ? NSS_STATUS_NOTFOUND : NSS_STATUS_TRYAGAIN);
+ return NSS_STATUS_TRYAGAIN;
}
-
static enum nss_status
gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname,
struct gaih_addrtuple ***patp,