From 5bf9892bb31da969f6751d15e26e2e51390a5e57 Mon Sep 17 00:00:00 2001
From: "Martine S. Lenders" <m.lenders@fu-berlin.de>
Date: Tue, 1 Oct 2019 16:36:14 +0200
Subject: [PATCH] gnrc_sixlowpan_frag_rb: add new functions for SFR

---
 sys/include/net/gnrc/sixlowpan/frag/rb.h      | 39 ++++++++++++++++
 .../frag/rb/gnrc_sixlowpan_frag_rb.c          | 44 +++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/sys/include/net/gnrc/sixlowpan/frag/rb.h b/sys/include/net/gnrc/sixlowpan/frag/rb.h
index b66b1d31d1..76091e270e 100644
--- a/sys/include/net/gnrc/sixlowpan/frag/rb.h
+++ b/sys/include/net/gnrc/sixlowpan/frag/rb.h
@@ -114,6 +114,45 @@ gnrc_sixlowpan_frag_rb_t *gnrc_sixlowpan_frag_rb_add(gnrc_netif_hdr_t *netif_hdr
                                                      gnrc_pktsnip_t *frag,
                                                      size_t offset, unsigned page);
 
+/**
+ * @brief   Checks if a reassembly buffer entry with a given link-layer address
+ *          pair and tag exists
+ *
+ * @pre     `netif_hdr != NULL`
+ *
+ * @param[in] netif_hdr An interface header to provide the (source, destination)
+ *                      link-layer address pair. Must not be NULL.
+ * @param[in] tag       Tag to search for.
+ *
+ * @note    datagram_size is not a search parameter as the primary use case
+ *          for this function is [Selective Fragment Recovery]
+ *          (https://tools.ietf.org/html/draft-ietf-6lo-fragment-recovery-05)
+ *          where this information only exists in the first fragment.
+ *
+ * @return  true, if an entry with the given tuple exist.
+ * @return  false, if no entry with the given tuple exist.
+ */
+bool gnrc_sixlowpan_frag_rb_exists(const gnrc_netif_hdr_t *netif_hdr,
+                                   uint16_t tag);
+
+/**
+ * @brief   Removes a reassembly buffer entry with a given link-layer address
+ *          pair and tag
+ *
+ * @pre     `netif_hdr != NULL`
+ *
+ * @param[in] netif_hdr An interface header to provide the (source, destination)
+ *                      link-layer address pair. Must not be NULL.
+ * @param[in] tag       Tag to search for.
+ *
+ * @note    datagram_size is not a search parameter as the primary use case
+ *          for this function is [Selective Fragment Recovery]
+ *          (https://tools.ietf.org/html/draft-ietf-6lo-fragment-recovery-05)
+ *          where this information only exists in the first fragment.
+ */
+void gnrc_sixlowpan_frag_rb_rm_by_datagram(const gnrc_netif_hdr_t *netif_hdr,
+                                           uint16_t tag);
+
 /**
  * @brief   Checks if a reassembly buffer entry is unset
  *
diff --git a/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c b/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c
index d0c8856fa4..d51dfb216d 100644
--- a/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c
+++ b/sys/net/gnrc/network_layer/sixlowpan/frag/rb/gnrc_sixlowpan_frag_rb.c
@@ -73,6 +73,9 @@ static int _rbuf_get(const void *src, size_t src_len,
                      const void *dst, size_t dst_len,
                      size_t size, uint16_t tag,
                      unsigned page);
+/* gets an entry only by link-layer information and tag */
+static gnrc_sixlowpan_frag_rb_t *_rbuf_get_by_tag(const gnrc_netif_hdr_t *netif_hdr,
+                                                  uint16_t tag);
 /* internal add to repeat add when fragments overlapped */
 static int _rbuf_add(gnrc_netif_hdr_t *netif_hdr, gnrc_pktsnip_t *pkt,
                      size_t offset, unsigned page);
@@ -138,6 +141,47 @@ gnrc_sixlowpan_frag_rb_t *gnrc_sixlowpan_frag_rb_add(gnrc_netif_hdr_t *netif_hdr
     return (res < 0) ? NULL : &rbuf[res];
 }
 
+
+
+bool gnrc_sixlowpan_frag_rb_exists(const gnrc_netif_hdr_t *netif_hdr,
+                                   uint16_t tag)
+{
+    return (_rbuf_get_by_tag(netif_hdr, tag) != NULL);
+}
+
+void gnrc_sixlowpan_frag_rb_rm_by_datagram(const gnrc_netif_hdr_t *netif_hdr,
+                                           uint16_t tag)
+{
+    gnrc_sixlowpan_frag_rb_t *e = _rbuf_get_by_tag(netif_hdr, tag);
+
+    if (e != NULL) {
+        gnrc_sixlowpan_frag_rb_remove(e);
+    }
+}
+
+static gnrc_sixlowpan_frag_rb_t *_rbuf_get_by_tag(const gnrc_netif_hdr_t *netif_hdr,
+                                                  uint16_t tag)
+{
+    assert(netif_hdr != NULL);
+    const uint8_t *src = gnrc_netif_hdr_get_src_addr(netif_hdr);
+    const uint8_t *dst = gnrc_netif_hdr_get_dst_addr(netif_hdr);
+    const uint8_t src_len = netif_hdr->src_l2addr_len;
+    const uint8_t dst_len = netif_hdr->dst_l2addr_len;
+
+    for (unsigned i = 0; i < GNRC_SIXLOWPAN_FRAG_RBUF_SIZE; i++) {
+        gnrc_sixlowpan_frag_rb_t *e = &rbuf[i];
+
+        if ((e->pkt != NULL) && (e->super.tag == tag) &&
+            (e->super.src_len == src_len) &&
+            (e->super.dst_len == dst_len) &&
+            (memcmp(e->super.src, src, src_len) == 0) &&
+            (memcmp(e->super.dst, dst, dst_len) == 0)) {
+            return e;
+        }
+    }
+    return NULL;
+}
+
 #ifndef NDEBUG
 static bool _valid_offset(gnrc_pktsnip_t *pkt, size_t offset)
 {