[mynewt-mcumgr] 01/05: zephyr - fragmentation of overly long responses.

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commit d03e76c77eb1c4bb0b3da54d2b099c3435868cfa
Author: Christopher Collins <cc...@apache.org>
AuthorDate: Thu Jan 4 13:24:35 2018 -0800

    zephyr - fragmentation of overly long responses.
---
 smp/port/zephyr/include/zephyr_smp/zephyr_smp.h | 13 ++++-
 smp/port/zephyr/src/zephyr_smp.c                | 72 +++++++++++++++----------
 2 files changed, 55 insertions(+), 30 deletions(-)

diff --git a/smp/port/zephyr/include/zephyr_smp/zephyr_smp.h b/smp/port/zephyr/include/zephyr_smp/zephyr_smp.h
index d74e8c4..c05ef01 100644
--- a/smp/port/zephyr/include/zephyr_smp/zephyr_smp.h
+++ b/smp/port/zephyr/include/zephyr_smp/zephyr_smp.h
@@ -14,7 +14,18 @@ struct zephyr_nmgr_pkt;
  */
 typedef int zephyr_smp_transport_out_fn(struct zephyr_smp_transport *zst,
                                         struct zephyr_nmgr_pkt *pkt);
-typedef uint16_t zephyr_smp_transport_get_mtu_fn(void);
+
+/**
+ * MTU query function.  The supplied packet should contain a request received
+ * from the peer whose MTU is being queried.  This function takes a packet
+ * parameter because some transports store connection-specific information in
+ * the packet (e.g., the BLE transport stores the connection pointer).
+ *
+ * @return                      The transport's MTU;
+ *                              0 if transmission is currently not possible.
+ */
+typedef uint16_t
+zephyr_smp_transport_get_mtu_fn(const struct zephyr_nmgr_pkt *pkt);
 
 struct zephyr_smp_transport {
     /* Must be the first member. */
diff --git a/smp/port/zephyr/src/zephyr_smp.c b/smp/port/zephyr/src/zephyr_smp.c
index 2262397..759006d 100644
--- a/smp/port/zephyr/src/zephyr_smp.c
+++ b/smp/port/zephyr/src/zephyr_smp.c
@@ -23,32 +23,6 @@ static const struct mgmt_streamer_cfg zephyr_smp_cbor_cfg = {
     .free_buf = zephyr_smp_free_buf,
 };
 
-#if 0
-/**
- * Allocates an mbuf to contain an outgoing response fragment.
- */
-static struct os_mbuf *
-zephyr_smp_rsp_frag_alloc(uint16_t frag_size, void *arg)
-{
-    struct os_mbuf *src_rsp;
-    struct os_mbuf *frag;
-
-    /* We need to duplicate the user header from the source response, as that
-     * is where transport-specific information is stored.
-     */
-    src_rsp = arg;
-
-    frag = os_msys_get_pkthdr(frag_size, OS_MBUF_USRHDR_LEN(src_rsp));
-    if (frag != NULL) {
-        /* Copy the user header from the response into the fragment mbuf. */
-        memcpy(OS_MBUF_USRHDR(frag), OS_MBUF_USRHDR(src_rsp),
-               OS_MBUF_USRHDR_LEN(src_rsp));
-    }
-
-    return frag;
-}
-#endif
-
 static void *
 zephyr_smp_alloc_rsp(const void *req, void *arg)
 {
@@ -68,6 +42,29 @@ zephyr_smp_alloc_rsp(const void *req, void *arg)
     return rsp_pkt;
 }
 
+static struct zephyr_nmgr_pkt *
+zephyr_smp_split_frag(struct zephyr_nmgr_pkt **pkt, uint16_t mtu)
+{
+    struct zephyr_nmgr_pkt *frag;
+    struct zephyr_nmgr_pkt *src;
+
+    src = *pkt;
+
+    if (src->len <= mtu) {
+        *pkt = NULL;
+        frag = src;
+    } else {
+        frag = zephyr_smp_alloc_rsp(src, NULL);
+        frag->len = mtu;
+        memcpy(frag->data, src->data, mtu);
+
+        src->len -= mtu;
+        memmove(src->data, src->data + mtu, src->len);
+    }
+
+    return frag;
+}
+
 static int
 zephyr_smp_trim_front(void *buf, int len, void *arg)
 {
@@ -126,18 +123,35 @@ static int
 zephyr_smp_tx_rsp(struct smp_streamer *ns, void *rsp, void *arg)
 {
     struct zephyr_smp_transport *zst;
+    struct zephyr_nmgr_pkt *frag;
     struct zephyr_nmgr_pkt *pkt;
+    uint16_t mtu;
     int rc;
+    int i;
 
     zst = arg;
     pkt = rsp;
 
-    rc = zst->zst_output(zst, pkt);
-    if (rc != 0) {
+    mtu = zst->zst_get_mtu(rsp);
+    if (mtu == 0) {
+        /* The transport cannot support a transmission right now. */
         return MGMT_ERR_EUNKNOWN;
     }
 
-    return MGMT_ERR_EOK;
+    i = 0;
+    while (pkt != NULL) {
+        frag = zephyr_smp_split_frag(&pkt, mtu);
+        if (frag == NULL) {
+            return MGMT_ERR_ENOMEM;
+        }
+
+        rc = zst->zst_output(zst, frag);
+        if (rc != 0) {
+            return MGMT_ERR_EUNKNOWN;
+        }
+    }
+
+    return 0;
 }
 
 static void

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