Add helper functions for info_callback and msg_callback.

This is getting a little repetitive.

Change-Id: Ib0fa8ab10149557c2d728b88648381b9368221d9
Reviewed-on: https://boringssl-review.googlesource.com/8126
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/ssl/dtls_record.c b/ssl/dtls_record.c
index eaf6df7..71d7ba5 100644
--- a/ssl/dtls_record.c
+++ b/ssl/dtls_record.c
@@ -195,10 +195,8 @@
     return ssl_open_record_discard;
   }
 
-  if (ssl->msg_callback != NULL) {
-    ssl->msg_callback(0 /* read */, 0, SSL3_RT_HEADER, in,
-                      DTLS1_RT_HEADER_LENGTH, ssl, ssl->msg_callback_arg);
-  }
+  ssl_do_msg_callback(ssl, 0 /* read */, 0, SSL3_RT_HEADER, in,
+                      DTLS1_RT_HEADER_LENGTH);
 
   uint16_t epoch = (((uint16_t)sequence[0]) << 8) | sequence[1];
   if (epoch != ssl->d1->r_epoch ||
@@ -299,10 +297,8 @@
 
   *out_len = DTLS1_RT_HEADER_LENGTH + ciphertext_len;
 
-  if (ssl->msg_callback) {
-    ssl->msg_callback(1 /* write */, 0, SSL3_RT_HEADER, out,
-                      DTLS1_RT_HEADER_LENGTH, ssl, ssl->msg_callback_arg);
-  }
+  ssl_do_msg_callback(ssl, 1 /* write */, 0, SSL3_RT_HEADER, out,
+                      DTLS1_RT_HEADER_LENGTH);
 
   return 1;
 }