From 9a75af81469d0f81dd4acaa5dbc911bf29e71bb8 Mon Sep 17 00:00:00 2001
From: Cory McWilliams <cory@unprompted.com>
Date: Sun, 6 Feb 2022 03:51:25 +0000
Subject: [PATCH] Don't add a message until its previous message exists.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@3830 ed5197a5-7fde-0310-b194-c3ffbd925b24
---
 src/ssb.db.c | 77 +++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 55 insertions(+), 22 deletions(-)

diff --git a/src/ssb.db.c b/src/ssb.db.c
index b1faf30e..1257907f 100644
--- a/src/ssb.db.c
+++ b/src/ssb.db.c
@@ -63,6 +63,31 @@ void tf_ssb_db_init(tf_ssb_t* ssb)
 		NULL, NULL, NULL);
 }
 
+static bool _tf_ssb_db_previous_message_exists(sqlite3* db, const char* author, int64_t sequence, const char* previous)
+{
+	bool exists = false;
+	if (sequence == 1)
+	{
+		exists = true;
+	}
+	else
+	{
+		sqlite3_stmt* statement;
+		if (sqlite3_prepare(db, "SELECT COUNT(*) FROM messages WHERE author = ?1 AND sequence = ?2 AND id = ?3", -1, &statement, NULL) == SQLITE_OK)
+		{
+			if (sqlite3_bind_text(statement, 1, author, -1, NULL) == SQLITE_OK &&
+				sqlite3_bind_int64(statement, 2, sequence - 1) == SQLITE_OK &&
+				sqlite3_bind_text(statement, 3, previous, -1, NULL) == SQLITE_OK &&
+				sqlite3_step(statement) == SQLITE_ROW)
+			{
+				exists = sqlite3_column_int(statement, 0) != 0;
+			}
+			sqlite3_finalize(statement);
+		}
+	}
+	return exists;
+}
+
 bool tf_ssb_db_store_message(tf_ssb_t* ssb, JSContext* context, const char* id, JSValue val, const char* signature, bool sequence_before_author)
 {
 	bool stored = false;
@@ -84,40 +109,48 @@ bool tf_ssb_db_store_message(tf_ssb_t* ssb, JSContext* context, const char* id,
 	sqlite3* db = tf_ssb_get_db(ssb);
 	sqlite3_stmt* statement;
 	int64_t last_row_id = -1;
-	const char* query = "INSERT INTO messages (id, previous, author, sequence, timestamp, content, hash, signature, sequence_before_author) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?) ON CONFLICT DO NOTHING";
-	if (sqlite3_prepare(db, query, -1, &statement, NULL) == SQLITE_OK)
+
+	if (_tf_ssb_db_previous_message_exists(db, author, sequence, previous))
 	{
-		if (sqlite3_bind_text(statement, 1, id, -1, NULL) == SQLITE_OK &&
-			(previous ? sqlite3_bind_text(statement, 2, previous, -1, NULL) : sqlite3_bind_null(statement, 2)) == SQLITE_OK &&
-			sqlite3_bind_text(statement, 3, author, -1, NULL) == SQLITE_OK &&
-			sqlite3_bind_int64(statement, 4, sequence) == SQLITE_OK &&
-			sqlite3_bind_int64(statement, 5, timestamp) == SQLITE_OK &&
-			sqlite3_bind_text(statement, 6, contentstr, content_len, NULL) == SQLITE_OK &&
-			sqlite3_bind_text(statement, 7, "sha256", 6, NULL) == SQLITE_OK &&
-			sqlite3_bind_text(statement, 8, signature, -1, NULL) == SQLITE_OK &&
-			sqlite3_bind_int(statement, 9, sequence_before_author) == SQLITE_OK)
+		const char* query = "INSERT INTO messages (id, previous, author, sequence, timestamp, content, hash, signature, sequence_before_author) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?) ON CONFLICT DO NOTHING";
+		if (sqlite3_prepare(db, query, -1, &statement, NULL) == SQLITE_OK)
 		{
-			int r = sqlite3_step(statement);
-			if (r != SQLITE_DONE)
+			if (sqlite3_bind_text(statement, 1, id, -1, NULL) == SQLITE_OK &&
+				(previous ? sqlite3_bind_text(statement, 2, previous, -1, NULL) : sqlite3_bind_null(statement, 2)) == SQLITE_OK &&
+				sqlite3_bind_text(statement, 3, author, -1, NULL) == SQLITE_OK &&
+				sqlite3_bind_int64(statement, 4, sequence) == SQLITE_OK &&
+				sqlite3_bind_int64(statement, 5, timestamp) == SQLITE_OK &&
+				sqlite3_bind_text(statement, 6, contentstr, content_len, NULL) == SQLITE_OK &&
+				sqlite3_bind_text(statement, 7, "sha256", 6, NULL) == SQLITE_OK &&
+				sqlite3_bind_text(statement, 8, signature, -1, NULL) == SQLITE_OK &&
+				sqlite3_bind_int(statement, 9, sequence_before_author) == SQLITE_OK)
 			{
-				printf("%s\n", sqlite3_errmsg(db));
-			}
-			stored = r == SQLITE_DONE && sqlite3_changes(db) != 0;
-			if (stored)
-			{
-				last_row_id = sqlite3_last_insert_rowid(db);
+				int r = sqlite3_step(statement);
+				if (r != SQLITE_DONE)
+				{
+					printf("%s\n", sqlite3_errmsg(db));
+				}
+				stored = r == SQLITE_DONE && sqlite3_changes(db) != 0;
+				if (stored)
+				{
+					last_row_id = sqlite3_last_insert_rowid(db);
+				}
 			}
+			sqlite3_finalize(statement);
+		}
+		else
+		{
+			printf("prepare failed: %s\n", sqlite3_errmsg(db));
 		}
-		sqlite3_finalize(statement);
 	}
 	else
 	{
-		printf("prepare failed: %s\n", sqlite3_errmsg(db));
+		printf("Previous message doesn't exist.\n");
 	}
 
 	if (last_row_id != -1)
 	{
-		query = "INSERT INTO blob_wants (id) SELECT DISTINCT json.value FROM messages, json_tree(messages.content) AS json LEFT OUTER JOIN blobs ON json.value = blobs.id WHERE messages.rowid = ?1 AND json.value LIKE '&%%.sha256' AND length(json.value) = ?2 AND blobs.content IS NULL ON CONFLICT DO NOTHING RETURNING id";
+		const char* query = "INSERT INTO blob_wants (id) SELECT DISTINCT json.value FROM messages, json_tree(messages.content) AS json LEFT OUTER JOIN blobs ON json.value = blobs.id WHERE messages.rowid = ?1 AND json.value LIKE '&%%.sha256' AND length(json.value) = ?2 AND blobs.content IS NULL ON CONFLICT DO NOTHING RETURNING id";
 		if (sqlite3_prepare(db, query, -1, &statement, NULL) == SQLITE_OK)
 		{
 			if (sqlite3_bind_int64(statement, 1, last_row_id) == SQLITE_OK &&