krb5 commit: Add KRB5_TRACE calls for DNS lookups

https://github.com/krb5/krb5/commit/a35577be95d5cede2d2673b7df065cb16f8cfc6d
commit a35577be95d5cede2d2673b7df065cb16f8cfc6d
Author: Matt Rogers <[email protected]>
Date:   Mon Oct 31 14:47:00 2016 -0400

    Add KRB5_TRACE calls for DNS lookups
    
    ticket: 8517 (new)

 src/include/k5-trace.h         |   14 +++++++++++++
 src/lib/krb5/os/dnsglue.h      |   13 ++++++-----
 src/lib/krb5/os/dnssrv.c       |   18 +++++++++-------
 src/lib/krb5/os/locate_kdc.c   |   43 +++++++++++++++++++++------------------
 src/lib/krb5/os/t_locate_kdc.c |    2 +-
 5 files changed, 55 insertions(+), 35 deletions(-)

diff --git a/src/include/k5-trace.h b/src/include/k5-trace.h
index c75e264..15b7e32 100644
--- a/src/include/k5-trace.h
+++ b/src/include/k5-trace.h
@@ -155,6 +155,20 @@ void krb5int_trace(krb5_context context, const char *fmt, ...);
     TRACE(c, "ccselect choosing default cache {ccache} for server " \
           "principal {princ}", cache, server)
 
+#define TRACE_DNS_SRV_ANS(c, host, port, prio, weight)                \
+    TRACE(c, "SRV answer: {int} {int} {int} \"{str}\"", prio, weight, \
+          port, host)
+#define TRACE_DNS_SRV_NOTFOUND(c)               \
+    TRACE(c, "No SRV records found")
+#define TRACE_DNS_SRV_SEND(c, domain)                   \
+    TRACE(c, "Sending DNS SRV query for {str}", domain)
+#define TRACE_DNS_URI_ANS(c, uri, prio, weight)                         \
+    TRACE(c, "URI answer: {int} {int} \"{str}\"", prio, weight, uri)
+#define TRACE_DNS_URI_NOTFOUND(c)               \
+    TRACE(c, "No URI records found")
+#define TRACE_DNS_URI_SEND(c, domain)                   \
+    TRACE(c, "Sending DNS URI query for {str}", domain)
+
 #define TRACE_FAST_ARMOR_CCACHE(c, ccache_name)         \
     TRACE(c, "FAST armor ccache: {str}", ccache_name)
 #define TRACE_FAST_ARMOR_CCACHE_KEY(c, keyblock)                \
diff --git a/src/lib/krb5/os/dnsglue.h b/src/lib/krb5/os/dnsglue.h
index 27147a6..b87e238 100644
--- a/src/lib/krb5/os/dnsglue.h
+++ b/src/lib/krb5/os/dnsglue.h
@@ -167,15 +167,16 @@ struct srv_dns_entry {
     char *host;
 };
 
-krb5_error_code krb5int_make_srv_query_realm(const krb5_data *realm,
-                                             const char *service,
-                                             const char *protocol,
-                                             struct srv_dns_entry **answers);
+krb5_error_code
+krb5int_make_srv_query_realm(krb5_context context, const krb5_data *realm,
+                             const char *service, const char *protocol,
+                             struct srv_dns_entry **answers);
+
 void krb5int_free_srv_dns_data(struct srv_dns_entry *);
 
 krb5_error_code
-k5_make_uri_query(const krb5_data *realm, const char *service,
-                  struct srv_dns_entry **answers);
+k5_make_uri_query(krb5_context context, const krb5_data *realm,
+                  const char *service, struct srv_dns_entry **answers);
 
 #endif /* KRB5_DNS_LOOKUP */
 #endif /* !defined(KRB5_DNSGLUE_H) */
diff --git a/src/lib/krb5/os/dnssrv.c b/src/lib/krb5/os/dnssrv.c
index 76f5b63..d66a8f9 100644
--- a/src/lib/krb5/os/dnssrv.c
+++ b/src/lib/krb5/os/dnssrv.c
@@ -104,8 +104,8 @@ place_srv_entry(struct srv_dns_entry **head, struct srv_dns_entry *new)
 
 /* Query the URI RR, collecting weight, priority, and target. */
 krb5_error_code
-k5_make_uri_query(const krb5_data *realm, const char *service,
-                  struct srv_dns_entry **answers)
+k5_make_uri_query(krb5_context context, const krb5_data *realm,
+                  const char *service, struct srv_dns_entry **answers)
 {
     const unsigned char *p = NULL, *base = NULL;
     char host[MAXDNAME];
@@ -121,6 +121,8 @@ k5_make_uri_query(const krb5_data *realm, const char *service,
     if (ret)
         return 0;
 
+    TRACE_DNS_URI_SEND(context, host);
+
     size = krb5int_dns_init(&ds, host, C_IN, T_URI);
     if (size < 0)
         goto out;
@@ -148,6 +150,7 @@ k5_make_uri_query(const krb5_data *realm, const char *service,
             goto out;
         }
 
+        TRACE_DNS_URI_ANS(context, uri->host, uri->priority, uri->weight);
         place_srv_entry(&head, uri);
     }
 
@@ -165,9 +168,8 @@ out:
  */
 
 krb5_error_code
-krb5int_make_srv_query_realm(const krb5_data *realm,
-                             const char *service,
-                             const char *protocol,
+krb5int_make_srv_query_realm(krb5_context context, const krb5_data *realm,
+                             const char *service, const char *protocol,
                              struct srv_dns_entry **answers)
 {
     const unsigned char *p = NULL, *base = NULL;
@@ -192,9 +194,7 @@ krb5int_make_srv_query_realm(const krb5_data *realm,
     if (ret)
         return 0;
 
-#ifdef TEST
-    fprintf(stderr, "sending DNS SRV query for %s\n", host);
-#endif
+    TRACE_DNS_SRV_SEND(context, host);
 
     size = krb5int_dns_init(&ds, host, C_IN, T_SRV);
     if (size < 0)
@@ -239,6 +239,8 @@ krb5int_make_srv_query_realm(const krb5_data *realm,
             goto out;
         }
 
+        TRACE_DNS_SRV_ANS(context, srv->host, srv->port, srv->priority,
+                          srv->weight);
         place_srv_entry(&head, srv);
     }
 
diff --git a/src/lib/krb5/os/locate_kdc.c b/src/lib/krb5/os/locate_kdc.c
index 014ec6e..b9edecc 100644
--- a/src/lib/krb5/os/locate_kdc.c
+++ b/src/lib/krb5/os/locate_kdc.c
@@ -313,14 +313,16 @@ krb5_locate_srv_conf(krb5_context context, const krb5_data *realm,
 
 #ifdef KRB5_DNS_LOOKUP
 static krb5_error_code
-locate_srv_dns_1(const krb5_data *realm, const char *service,
-                 const char *protocol, struct serverlist *serverlist)
+locate_srv_dns_1(krb5_context context, const krb5_data *realm,
+                 const char *service, const char *protocol,
+                 struct serverlist *serverlist)
 {
     struct srv_dns_entry *head = NULL, *entry = NULL;
     krb5_error_code code = 0;
     k5_transport transport;
 
-    code = krb5int_make_srv_query_realm(realm, service, protocol, &head);
+    code = krb5int_make_srv_query_realm(context, realm, service, protocol,
+                                        &head);
     if (code)
         return 0;
 
@@ -598,9 +600,10 @@ parse_uri_fields(const char *uri, k5_transport *transport_out,
  * and transport type.  Problematic entries are skipped.
  */
 static krb5_error_code
-locate_uri(const krb5_data *realm, const char *req_service,
-           struct serverlist *serverlist, k5_transport req_transport,
-           int default_port, krb5_boolean master_only)
+locate_uri(krb5_context context, const krb5_data *realm,
+           const char *req_service, struct serverlist *serverlist,
+           k5_transport req_transport, int default_port,
+           krb5_boolean master_only)
 {
     krb5_error_code ret;
     k5_transport transport, host_trans;
@@ -609,7 +612,7 @@ locate_uri(const krb5_data *realm, const char *req_service,
     const char *host_field, *path;
     int port, def_port, master;
 
-    ret = k5_make_uri_query(realm, req_service, &answers);
+    ret = k5_make_uri_query(context, realm, req_service, &answers);
     if (ret || answers == NULL)
         return ret;
 
@@ -688,10 +691,11 @@ dns_locate_server_uri(krb5_context context, const krb5_data *realm,
         return 0;
     }
 
-    ret = locate_uri(realm, svcname, serverlist, transport, def_port,
+    ret = locate_uri(context, realm, svcname, serverlist, transport, def_port,
                      find_master);
-    if (ret)
-        Tprintf("dns URI lookup returned error %d\n", ret);
+
+    if (serverlist->nservers == 0)
+        TRACE_DNS_URI_NOTFOUND(context);
 
     return ret;
 }
@@ -729,16 +733,15 @@ dns_locate_server_srv(krb5_context context, const krb5_data *realm,
     }
 
     code = 0;
-    if (transport == UDP || transport == TCP_OR_UDP) {
-        code = locate_srv_dns_1(realm, dnsname, "_udp", serverlist);
-        if (code)
-            Tprintf("dns udp lookup returned error %d\n", code);
-    }
-    if ((transport == TCP || transport == TCP_OR_UDP) && code == 0) {
-        code = locate_srv_dns_1(realm, dnsname, "_tcp", serverlist);
-        if (code)
-            Tprintf("dns tcp lookup returned error %d\n", code);
-    }
+    if (transport == UDP || transport == TCP_OR_UDP)
+        code = locate_srv_dns_1(context, realm, dnsname, "_udp", serverlist);
+
+    if ((transport == TCP || transport == TCP_OR_UDP) && code == 0)
+        code = locate_srv_dns_1(context, realm, dnsname, "_tcp", serverlist);
+
+    if (serverlist->nservers == 0)
+        TRACE_DNS_SRV_NOTFOUND(context);
+
     return code;
 }
 #endif /* KRB5_DNS_LOOKUP */
diff --git a/src/lib/krb5/os/t_locate_kdc.c b/src/lib/krb5/os/t_locate_kdc.c
index 6414b8e..7a53c84 100644
--- a/src/lib/krb5/os/t_locate_kdc.c
+++ b/src/lib/krb5/os/t_locate_kdc.c
@@ -127,7 +127,7 @@ main (int argc, char *argv[])
         break;
 
     case LOOKUP_DNS:
-        err = locate_srv_dns_1(&realm, "_kerberos", "_udp", &sl);
+        err = locate_srv_dns_1(ctx, &realm, "_kerberos", "_udp", &sl);
         break;
 
     case LOOKUP_WHATEVER: