Fix spurious DNS lookups in the C library.
The problem was that the 'defdname' field of res_state structure
was not properly initialized in __res_vinit(). This field is used
to store the default domain name, which is normally build from
calling gethostname() (see line 549 of res_init.c).
Unfortunately, in the typical Android case, gethostname() returns
an error (the hostname is configured) and a random stack string is
used later to build the DNS search list (see lines 556+ in res_init.c)
For the sake of illustration, let's say the search list is set to
a random value like 'xWLK'.
The end result is that when trying to result an unknown domain name
(e.g. 'www.ptn'), the query fails then the resolver tries to make a
new query with the DNS search list path(s) appended (e.g. 'www.ptn.xWLK').
The patch simply initializes 'defdname' to an empty string to avoid
this when the net.dns.search system property is not set.
Also contains whitespace/formatting fixes
diff --git a/libc/docs/CHANGES.TXT b/libc/docs/CHANGES.TXT
index c053714..4f87547 100644
--- a/libc/docs/CHANGES.TXT
+++ b/libc/docs/CHANGES.TXT
@@ -76,6 +76,10 @@
- <time.h>: Fix timezone management implementation to properly update
'tm_gmtoff' field in 'struct tm' structure.
+- DNS: get rid of spurious random DNS queries when trying to resolve
+ an unknown domain name. Due to an initialization bug, a random DNS search
+ list was generated for each thread is net.dns.search is not defined.
+
-------------------------------------------------------------------------------
Differences between Android 2.1 and 2.0.1:
diff --git a/libc/netbsd/resolv/res_cache.c b/libc/netbsd/resolv/res_cache.c
index 2c912de..2621a7b 100644
--- a/libc/netbsd/resolv/res_cache.c
+++ b/libc/netbsd/resolv/res_cache.c
@@ -251,7 +251,7 @@
return p;
va_start(args, format);
- n = snprintf( p, avail, format, args);
+ n = vsnprintf( p, avail, format, args);
va_end(args);
/* certain C libraries return -1 in case of truncation */
diff --git a/libc/netbsd/resolv/res_init.c b/libc/netbsd/resolv/res_init.c
index 751603d..81e570f 100644
--- a/libc/netbsd/resolv/res_init.c
+++ b/libc/netbsd/resolv/res_init.c
@@ -198,6 +198,8 @@
if (pp > statp->dnsrch)
return 1;
}
+ statp->defdname[0] = '\0'; /* no default domain name on Android */
+ statp->dnsrch[0] = NULL;
return 0;
}
#endif
@@ -381,7 +383,7 @@
/* Add the domain search list */
havesearch = load_domain_search_list(statp);
-#else /* IGNORE resolv.conf */
+#else /* !ANDROID_CHANGES - IGNORE resolv.conf in Android */
#define MATCH(line, name) \
(!strncmp(line, name, sizeof(name) - 1) && \
(line[sizeof(name) - 1] == ' ' || \
@@ -534,7 +536,7 @@
statp->nsort = nsort;
(void) fclose(fp);
}
-#endif /* ANDROID_CHANGES */
+#endif /* !ANDROID_CHANGES */
/*
* Last chance to get a nameserver. This should not normally
* be necessary
diff --git a/libc/private/arpa_nameser.h b/libc/private/arpa_nameser.h
index 2d2a739..438dc04 100644
--- a/libc/private/arpa_nameser.h
+++ b/libc/private/arpa_nameser.h
@@ -566,4 +566,12 @@
#include "arpa_nameser_compat.h"
#endif
+#if 0
+# include <logd.h>
+# define XLOG(...) \
+ __libc_android_log_print(ANDROID_LOG_DEBUG,"libc",__VA_ARGS__)
+#else
+#define XLOG(...) do {} while (0)
+#endif
+
#endif /* !_ARPA_NAMESER_H_ */
diff --git a/libc/unistd/gethostname.c b/libc/unistd/gethostname.c
index 369d21e..5d3d7d9 100644
--- a/libc/unistd/gethostname.c
+++ b/libc/unistd/gethostname.c
@@ -41,11 +41,11 @@
int namelen = strlen(name.nodename);
if ((int)buflen < namelen+1) {
- errno = EINVAL;
+ errno = EINVAL;
result = -1;
} else {
memcpy( buff, name.nodename, namelen+1 );
- }
+ }
}
return result;
}
