From 333bb408e1d9b900733565bc48b33b37f7a837c9 Mon Sep 17 00:00:00 2001
From: nemunaire <nemunaire@nemunai.re>
Date: Wed, 21 Nov 2018 03:22:42 +0100
Subject: [PATCH] backend: save the checksum of each try, to be able to detect
 duplicates after

---
 backend/submission.go | 11 ++++++++++-
 libfic/db.go          |  1 +
 libfic/exercice.go    |  8 ++++----
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/backend/submission.go b/backend/submission.go
index 41e00b1b..ece2eb02 100644
--- a/backend/submission.go
+++ b/backend/submission.go
@@ -11,6 +11,8 @@ import (
 	"os"
 	"strconv"
 
+	"golang.org/x/crypto/blake2b"
+
 	"srs.epita.fr/fic-server/libfic"
 )
 
@@ -54,6 +56,13 @@ func treatSubmission(pathname string, team fic.Team, exercice_id string) {
 		return
 	}
 
+	// Save checksum to treat duplicates
+	cksum := blake2b.Sum512(cnt_raw)
+	if err != nil {
+		log.Println(id, "[ERR] JSON parsing error:", err)
+		return
+	}
+
 	// Parse it
 	var responses ResponsesUpload
 	err = json.Unmarshal(cnt_raw, &responses)
@@ -70,7 +79,7 @@ func treatSubmission(pathname string, team fic.Team, exercice_id string) {
 	}
 
 	// Check given answers
-	solved, err := exercice.CheckResponse(responses.Keys, responses.MCQs, team)
+	solved, err := exercice.CheckResponse(cksum[:], responses.Keys, responses.MCQs, team)
 	if err != nil {
 		log.Println(id, "[ERR] Unable to CheckResponse:", err)
 		genTeamMyFile(team)
diff --git a/libfic/db.go b/libfic/db.go
index a32bc22b..b446805f 100644
--- a/libfic/db.go
+++ b/libfic/db.go
@@ -244,6 +244,7 @@ CREATE TABLE IF NOT EXISTS exercice_tries(
   id_exercice INTEGER NOT NULL,
   id_team INTEGER NOT NULL,
   time TIMESTAMP NOT NULL,
+  cksum BINARY(64) NOT NULL,
   nbdiff INTEGER NOT NULL DEFAULT 0,
   FOREIGN KEY(id_exercice) REFERENCES exercices(id_exercice),
   FOREIGN KEY(id_team) REFERENCES teams(id_team)
diff --git a/libfic/exercice.go b/libfic/exercice.go
index 15273b08..8ec7f32e 100644
--- a/libfic/exercice.go
+++ b/libfic/exercice.go
@@ -205,8 +205,8 @@ func (e Exercice) GetLevel() (int, error) {
 }
 
 // NewTry registers a solving attempt for the given Team.
-func (e Exercice) NewTry(t Team) error {
-	if _, err := DBExec("INSERT INTO exercice_tries (id_exercice, id_team, time) VALUES (?, ?, ?)", e.Id, t.Id, time.Now()); err != nil {
+func (e Exercice) NewTry(t Team, cksum []byte) error {
+	if _, err := DBExec("INSERT INTO exercice_tries (id_exercice, id_team, time, cksum) VALUES (?, ?, ?, ?)", e.Id, t.Id, time.Now(), cksum); err != nil {
 		return err
 	} else {
 		return nil
@@ -264,8 +264,8 @@ func (e Exercice) TriedCount() int64 {
 
 // CheckResponse, given both flags and MCQ responses, figures out if thoses are correct (or if they are previously solved).
 // In the meanwhile, CheckResponse registers good answers given (but it does not mark the challenge as solved at the end).
-func (e Exercice) CheckResponse(respflags map[string]string, respmcq map[int64]bool, t Team) (bool, error) {
-	if err := e.NewTry(t); err != nil {
+func (e Exercice) CheckResponse(cksum []byte, respflags map[string]string, respmcq map[int64]bool, t Team) (bool, error) {
+	if err := e.NewTry(t, cksum); err != nil {
 		return false, err
 	} else if flags, err := e.GetFlags(); err != nil {
 		return false, err