mbuf: add function to read packet data

[dpdk.git] / lib / librte_mbuf / rte_mbuf.c

diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index 05ae648..04f9ed3 100644 (file)
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -58,6 +58,7 @@
 #include <rte_string_fns.h>
 #include <rte_hexdump.h>
 #include <rte_errno.h>
+#include <rte_memcpy.h>
 
 /*
  * ctrlmbuf constructor, given as a callback function to
@@ -263,6 +264,40 @@ rte_pktmbuf_dump(FILE *f, const struct rte_mbuf *m, unsigned dump_len)
        }
 }
 
+/* read len data bytes in a mbuf at specified offset (internal) */
+const void *__rte_pktmbuf_read(const struct rte_mbuf *m, uint32_t off,
+       uint32_t len, void *buf)
+{
+       const struct rte_mbuf *seg = m;
+       uint32_t buf_off = 0, copy_len;
+
+       if (off + len > rte_pktmbuf_pkt_len(m))
+               return NULL;
+
+       while (off >= rte_pktmbuf_data_len(seg)) {
+               off -= rte_pktmbuf_data_len(seg);
+               seg = seg->next;
+       }
+
+       if (off + len <= rte_pktmbuf_data_len(seg))
+               return rte_pktmbuf_mtod_offset(seg, char *, off);
+
+       /* rare case: header is split among several segments */
+       while (len > 0) {
+               copy_len = rte_pktmbuf_data_len(seg) - off;
+               if (copy_len > len)
+                       copy_len = len;
+               rte_memcpy((char *)buf + buf_off,
+                       rte_pktmbuf_mtod_offset(seg, char *, off), copy_len);
+               off = 0;
+               buf_off += copy_len;
+               len -= copy_len;
+               seg = seg->next;
+       }
+
+       return buf;
+}
+
 /*
  * Get the name of a RX offload flag. Must be kept synchronized with flag
  * definitions in rte_mbuf.h.