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authorRich Felker <dalias@aerifal.cx>2014-06-02 02:13:57 -0400
committerRich Felker <dalias@aerifal.cx>2014-06-02 02:13:57 -0400
commit8312f7f60f9dfe88118163d38b8282abf04aac2f (patch)
tree0dcbcbd3f9e6b3362a920707895624bdc3adb1f5 /src/network/res_mkquery.c
parent1871f583f419f58bbcd921cda41c991994672c8a (diff)
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implement new dns backend, res_send and other legacy resolver functions
this is the second phase of the "resolver overhaul" project. the key additions in this commit are the __res_msend and __res_mkquery functions, which have been factored so as to provide a backend for both the legacy res_* functions and the standard getaddrinfo and getnameinfo functions. the latter however are still using the old backend code; there is code duplication which still needs to be removed, and this will be the next phase of the resolver overhaul. __res_msend is derived from the old __dns_doqueries function, but generalized to send arbitrary caller-provided packets in parallel rather than producing the parallel queries itself. this allows it to be used (completely trivially) as a backend for res_send. the factored-out query generation code, with slightly more generality, is now part of __res_mkquery.
Diffstat (limited to 'src/network/res_mkquery.c')
-rw-r--r--src/network/res_mkquery.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/src/network/res_mkquery.c b/src/network/res_mkquery.c
new file mode 100644
index 00000000..f7e4e9c6
--- /dev/null
+++ b/src/network/res_mkquery.c
@@ -0,0 +1,41 @@
+#include <resolv.h>
+#include <string.h>
+#include <time.h>
+#include "libc.h"
+
+int __res_mkquery(int op, const char *dname, int class, int type,
+ const unsigned char *data, int datalen,
+ const unsigned char *newrr, unsigned char *buf, int buflen)
+{
+ int id, i, j;
+ unsigned char q[280];
+ struct timespec ts;
+ size_t l = strnlen(dname, 256);
+
+ if (l-1>=254 || buflen<18+l || op>15u || class>255u || type>255u)
+ return -1;
+
+ /* Construct query template - ID will be filled later */
+ memset(q, 0, 18+l);
+ q[2] = op*8 + 1;
+ q[5] = 1;
+ memcpy((char *)q+13, dname, l);
+ for (i=13; q[i]; i=j+1) {
+ for (j=i; q[j] && q[j] != '.'; j++);
+ if (j-i-1u > 62u) return -1;
+ q[i-1] = j-i;
+ }
+ q[i+1] = type;
+ q[i+3] = class;
+
+ /* Make a reasonably unpredictable id */
+ clock_gettime(CLOCK_REALTIME, &ts);
+ id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff;
+ q[0] = id/256;
+ q[1] = id;
+
+ memcpy(buf, q, 18+l);
+ return 18+l;
+}
+
+weak_alias(__res_mkquery, res_mkquery);