res/res_rtp_asterisk: Fix crash in debug from RTCP reports without report block

When RTCP debugging was enabled, an RTCP report without a report block would
cause a crash. This was due to the verbose output not checking to see if the
report_block pointer was NULl before dereferencing it.

This patch adds the necessary check to prevent printing any verbose output
if the far side hasn't provided us the information they should have.

ASTERISK-24791 #close
Reported by: JoshE
Tested by: JoshE
........

Merged revisions 431879 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@431880 65c4cc65-6c06-0410-ace0-fbb531ad65f3

res/res_rtp_asterisk.c

@@ -3056,14 +3056,16 @@ static int ast_rtcp_write_report(struct ast_rtp_instance *instance, int sr)
 			ast_verbose("  Sent packets: %u\n", rtcp_report->sender_information.packet_count);
 			ast_verbose("  Sent octets: %u\n", rtcp_report->sender_information.octet_count);
 		}
-		ast_verbose("  Report block:\n");
-		ast_verbose("    Their SSRC: %u\n", report_block->source_ssrc);
-		ast_verbose("    Fraction lost: %d\n", report_block->lost_count.fraction);
-		ast_verbose("    Cumulative loss: %u\n", report_block->lost_count.packets);
-		ast_verbose("    Highest seq no: %u\n", report_block->highest_seq_no);
-		ast_verbose("    IA jitter: %.4f\n", (double)report_block->ia_jitter / rate);
-		ast_verbose("    Their last SR: %u\n", report_block->lsr);
-		ast_verbose("    DLSR: %4.4f (sec)\n\n", (double)(report_block->dlsr / 65536.0));
+		if (report_block) {
+			ast_verbose("  Report block:\n");
+			ast_verbose("    Their SSRC: %u\n", report_block->source_ssrc);
+			ast_verbose("    Fraction lost: %d\n", report_block->lost_count.fraction);
+			ast_verbose("    Cumulative loss: %u\n", report_block->lost_count.packets);
+			ast_verbose("    Highest seq no: %u\n", report_block->highest_seq_no);
+			ast_verbose("    IA jitter: %.4f\n", (double)report_block->ia_jitter / rate);
+			ast_verbose("    Their last SR: %u\n", report_block->lsr);
+			ast_verbose("    DLSR: %4.4f (sec)\n\n", (double)(report_block->dlsr / 65536.0));
+		}
 	}
 
 	ast_rtp_instance_get_local_address(instance, &local_address);