From 6fd95cc03cd02236457d6eb97e86deff3cd45ddf Mon Sep 17 00:00:00 2001
From: Matthias Kruk <m@m10k.eu>
Date: Fri, 25 Oct 2019 15:45:33 +0900
Subject: [PATCH] Add mbuf type and functions to allocate and free them

---
 config.h             |  3 ++-
 include/sys/mbuf.h   | 42 ++++++++++++++++++++++++++++++
 kernel/core/Makefile |  2 +-
 kernel/core/mbuf.c   | 61 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 106 insertions(+), 2 deletions(-)
 create mode 100644 include/sys/mbuf.h
 create mode 100644 kernel/core/mbuf.c

diff --git a/config.h b/config.h
index 502a336..04b15c5 100644
--- a/config.h
+++ b/config.h
@@ -41,7 +41,8 @@
 #define CONFIG_DEBUG_SCHED 0
 #define CONFIG_DEBUG_NET   1
 
-#define CONFIG_SOCKET_MAX  1024
+#define CONFIG_SOCKET_MAX    1024
+#define CONFIG_NET_MBUF_SIZE 2048
 
 /* sanity checks */
 
diff --git a/include/sys/mbuf.h b/include/sys/mbuf.h
new file mode 100644
index 0000000..1472e32
--- /dev/null
+++ b/include/sys/mbuf.h
@@ -0,0 +1,42 @@
+#ifndef __CORAX_MBUF_H__
+#define __CORAX_MBUF_H__
+
+#include <config.h>
+
+struct mbuf {
+	struct mbuf *m_next;
+	struct mbuf *m_nextpkt;
+	void        *m_data;
+	u16_t       m_len;
+	u8_t        m_type;
+	u8_t        m_flags;
+
+	union {
+		struct {
+			void *MH_rcvif;
+			u16_t MH_len;
+			u32_t MH_csum_flags;
+			u32_t MH_csum_data;
+		} M_hdr;
+		u8_t        M_databuf[CONFIG_NET_MBUF_SIZE];
+	} M_dat;
+} __attribute__((packed));
+
+#define m_rcvif     M_dat.M_hdr.MH_rcvif
+#define m_pktlen    M_dat.M_hdr.MH_len
+#define m_csumflags M_dat.M_hdr.MH_csum_flags
+#define m_csumdata  M_dat.M_hdr.MH_csum_data
+
+#define MT_NOTMBUF    0
+#define MT_DATA       1
+#define MT_HEADER     2
+#define MT_SONAME     3
+#define MT_CONTROL    4
+#define MT_EXTCONTROL 5
+#define MT_OOBDATA    6
+
+
+struct mbuf* mbuf_alloc(void);
+void mbuf_free(struct mbuf*);
+
+#endif /* __CORAX_MBUF_H__ */
diff --git a/kernel/core/Makefile b/kernel/core/Makefile
index b9a74e0..ef8b7c5 100644
--- a/kernel/core/Makefile
+++ b/kernel/core/Makefile
@@ -1,4 +1,4 @@
-OBJECTS = main.o process.o sched.o cxnet.o socket.o
+OBJECTS = main.o process.o sched.o cxnet.o socket.o mbuf.o
 OUTPUT = core.o
 INCLUDES = -I../include -I../../include -I../..
 CFLAGS += $(INCLUDES)
diff --git a/kernel/core/mbuf.c b/kernel/core/mbuf.c
new file mode 100644
index 0000000..c479beb
--- /dev/null
+++ b/kernel/core/mbuf.c
@@ -0,0 +1,61 @@
+#include <config.h>
+#include <corax/types.h>
+#include <corax/errno.h>
+#include <sys/mbuf.h>
+#include <debug.h>
+#define ALLOC_SIZE 128
+
+static struct mbuf *_unused;
+
+static struct mbuf* _alloc_mbufs(void)
+{
+	struct mbuf *m;
+
+	m = kmalloc(sizeof(*m) * ALLOC_SIZE);
+
+	if(m) {
+		int n;
+
+		/* skip the last mbuf so its m_next member remains NULL */
+		for(n = 0; n < (ALLOC_SIZE - 1); n++) {
+			m[n].m_next = m + 1;
+		}
+	}
+
+	return(m);
+}
+
+struct mbuf* mbuf_alloc(void)
+{
+	struct mbuf *m;
+
+	if(!_unused) {
+		/* need to allocate more mbufs */
+		_unused = _alloc_mbufs();
+	}
+
+	m = _unused;
+
+	if(m) {
+		_unused = m->m_next;
+
+		/*
+		 * Clear the mbuf's m_next member so the caller can't access more
+		 * mbufs than they're supposed to
+		 */
+		m->m_next = NULL;
+	}
+
+	return(m);
+}
+
+void mbuf_free(struct mbuf *m)
+{
+	/* clear the mbuf and prepend it to the list of unused mbufs */
+	memset(m, 0, sizeof(*m));
+
+	m->m_next = _unused;
+	_unused = m;
+
+	return;
+}
-- 
2.47.3