1 files changed, 103 insertions, 0 deletions

diff --git a/core/ping.c b/core/ping.c
new file mode 100644
index 00000000..ffabe221
--- /dev/null
+++ b/core/ping.c
@@ -0,0 +1,103 @@
+/*
+ * ping.c -- Buffered pinging using cyclic arrays.
+ *
+ * This file is donated to the Tox Project.
+ * Copyright 2013  plutooo
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "network.h"
+#include "util.h"
+
+#define PING_NUM_MAX 256
+#define PING_TIMEOUT 5 // 5s
+
+typedef struct {
+    IP_Port  ipp;
+    uint64_t id;
+    uint64_t timestamp;
+} pinged_t;
+
+static pinged_t pings[PING_NUM_MAX];
+static size_t   num_pings;
+static size_t   pos_pings;
+
+
+void init_ping()
+{
+    num_pings = 0;
+    pos_pings = 0;
+}
+
+static bool is_timeout(uint64_t time)
+{
+    return (time + PING_TIMEOUT) < now();
+}
+
+static void remove_timeouts()   // O(n)
+{
+    size_t i, id;
+    size_t new_pos = pos_pings;
+    size_t new_num = num_pings;
+
+    // Loop through buffer, oldest first
+    for (i=0; i<num_pings; i++) {
+        id = (pos_pings + i) % PING_NUM_MAX;
+
+        if(is_timeout(pings[id].timestamp)) {
+            new_pos++;
+            new_num--;
+        }
+        // Break here because list is sorted.
+        else
+            break;
+    }
+
+    num_pings = new_num;
+    pos_pings = new_pos % PING_NUM_MAX;
+}
+
+uint64_t add_ping(IP_Port ipp)   // O(n)
+{
+    size_t p;
+
+    remove_timeouts();
+
+    // Remove oldest ping if full buffer
+    if (num_pings == PING_NUM_MAX) {
+        num_pings--;
+        pos_pings = (pos_pings + 1) % PING_NUM_MAX;
+    }
+
+    // Insert new ping at end of list
+    p = (pos_pings + num_pings) % PING_NUM_MAX;
+
+    pings[p].ipp       = ipp;
+    pings[p].timestamp = now();
+    pings[p].id        = random_64b();
+
+    num_pings++;
+    return pings[p].id;
+}
+
+bool is_pinging(IP_Port ipp, uint64_t ping_id)   // O(n) TODO: replace this with something else.
+{
+    if (ipp.ip.i == 0 && ping_id == 0)
+        return false;
+    
+    size_t i, id;
+
+    remove_timeouts();
+
+    for (i=0; i<num_pings; i++) {
+        id = (pos_pings + i) % PING_NUM_MAX;
+
+        if ((ipp_eq(pings[id].ipp, ipp) || ipp.ip.i == 0) && (pings[id].id == ping_id || ping_id == 0)) {
+            return true;
+        }
+    }
+
+    return false;
+}