From 954e0227d4fbcc879f5f662e94940a2be34636d9 Mon Sep 17 00:00:00 2001
From: Cory McWilliams <cory@unprompted.com>
Date: Fri, 14 Oct 2022 17:39:08 +0000
Subject: [PATCH] When checking database integrity, delete messages after a
 gap.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@4005 ed5197a5-7fde-0310-b194-c3ffbd925b24
---
 src/ssb.db.c | 59 +++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 42 insertions(+), 17 deletions(-)

diff --git a/src/ssb.db.c b/src/ssb.db.c
index 0edbf654..c4af262b 100644
--- a/src/ssb.db.c
+++ b/src/ssb.db.c
@@ -731,6 +731,8 @@ bool tf_ssb_db_check(sqlite3* db, const char* check_author)
 			sqlite3_bind_text(statement, 1, check_author, -1, NULL);
 		}
 		char previous_id[k_id_base64_len];
+		int64_t previous_sequence = -1;
+		char previous_author[k_id_base64_len] = { 0 };
 		while (sqlite3_step(statement) == SQLITE_ROW)
 		{
 			const char* id = (const char*)sqlite3_column_text(statement, 0);
@@ -748,28 +750,47 @@ bool tf_ssb_db_check(sqlite3* db, const char* check_author)
 			bool actual_sequence_before_author = false;
 			JSValue j = JS_JSONStringify(context, message, JS_NULL, JS_NewInt32(context, 2));
 			const char* jv = JS_ToCString(context, j);
-			if (tf_ssb_verify_and_strip_signature(context, message, actual_id, sizeof(actual_id), out_signature, sizeof(out_signature), &actual_sequence_before_author))
+
+			bool delete_following = false;
+			if (strcmp(author, previous_author))
 			{
-				if (previous && strcmp(previous, previous_id))
-				{
-					printf("%s:%d previous was %s should be %s\n", id, (int)sequence, previous_id, previous);
-				}
-				if (strcmp(id, actual_id))
-				{
-					if (_tf_ssb_update_message_id(db, id, actual_id))
-					{
-						printf("updated %s to %s\n", id, actual_id);
-					}
-					else
-					{
-						printf("failed to update %s to %s\n", id, actual_id);
-					}
-				}
+				printf("%s\n", author);
+			}
+
+			if (strcmp(author, previous_author) == 0 && sequence != previous_sequence + 1)
+			{
+				printf("Detected gap in messages for %s at sequence = %" PRId64 " => %" PRId64 ".\n", author, previous_sequence, sequence);
+				delete_following = true;
 			}
 			else
 			{
-				printf("%s sequence=%" PRId64 " unable to verify signature for %s sequence_before_author=%d message=[%.*s]\n", author, sequence, id, sequence_before_author, (int)strlen(jv), jv);
+				if (tf_ssb_verify_and_strip_signature(context, message, actual_id, sizeof(actual_id), out_signature, sizeof(out_signature), &actual_sequence_before_author))
+				{
+					if (previous && strcmp(previous, previous_id))
+					{
+						printf("%s:%d previous was %s should be %s\n", id, (int)sequence, previous_id, previous);
+					}
+					if (strcmp(id, actual_id))
+					{
+						if (_tf_ssb_update_message_id(db, id, actual_id))
+						{
+							printf("updated %s to %s\n", id, actual_id);
+						}
+						else
+						{
+							printf("failed to update %s to %s\n", id, actual_id);
+						}
+					}
+				}
+				else
+				{
+					printf("%s sequence=%" PRId64 " unable to verify signature for %s sequence_before_author=%d message=[%.*s]\n", author, sequence, id, sequence_before_author, (int)strlen(jv), jv);
+					delete_following = true;
+				}
+			}
 
+			if (delete_following)
+			{
 				printf("Deleting author = %s sequence >= %" PRId64 ".\n", author, sequence);
 				sqlite3_stmt* delete_statement = NULL;
 				if (sqlite3_prepare(db, "DELETE FROM messages WHERE author = ? AND sequence >= ?", -1, &delete_statement, NULL) == SQLITE_OK)
@@ -785,6 +806,10 @@ bool tf_ssb_db_check(sqlite3* db, const char* check_author)
 					sqlite3_finalize(delete_statement);
 				}
 			}
+
+			snprintf(previous_author, sizeof(previous_author), "%s", author);
+			previous_sequence = sequence;
+
 			JS_FreeCString(context, jv);
 			JS_FreeValue(context, j);
 			snprintf(previous_id, sizeof(previous_id), "%s", id);