src/slirp/mbuf.c

/*
 * Copyright (c) 1995 Danny Gasparovski
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

/*
 * mbuf's in SLiRP are much simpler than the real mbufs in
 * FreeBSD.  They are fixed size, determined by the MTU,
 * so that one whole packet can fit.  Mbuf's cannot be
 * chained together.  If there's more data than the mbuf
 * could hold, an external malloced buffer is pointed to
 * by m_ext (and the data pointers) and M_EXT is set in
 * the flags
 */

#include <slirp.h>

struct  mbuf *mbutl;
char    *mclrefcnt;
int mbuf_alloced = 0;
struct mbuf m_freelist, m_usedlist;
int mbuf_thresh = 30;
int mbuf_max = 0;
int msize;

void
m_init()
{
        m_freelist.m_next = m_freelist.m_prev = &m_freelist;
        m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist;
        msize_init();
}

void
msize_init()
{
        /*
         * Find a nice value for msize
         * XXX if_maxlinkhdr already in mtu
         */
        msize = (if_mtu>if_mru?if_mtu:if_mru) + 
                        if_maxlinkhdr + sizeof(struct m_hdr ) + 6;
}

/*
 * Get an mbuf from the free list, if there are none
 * malloc one
 * 
 * Because fragmentation can occur if we alloc new mbufs and
 * free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE,
 * which tells m_free to actually free() it
 */
struct mbuf *
m_get()
{
        register struct mbuf *m;
        int flags = 0;
        
        DEBUG_CALL("m_get");
        
        if (m_freelist.m_next == &m_freelist) {
                m = (struct mbuf *)malloc(msize);
                if (m == NULL) goto end_error;
                mbuf_alloced++;
                if (mbuf_alloced > mbuf_thresh)
                        flags = M_DOFREE;
                if (mbuf_alloced > mbuf_max)
                        mbuf_max = mbuf_alloced;
        } else {
                m = m_freelist.m_next;
                remque(m);
        }
        
        /* Insert it in the used list */
        insque(m,&m_usedlist);
        m->m_flags = (flags | M_USEDLIST);
        
        /* Initialise it */
        m->m_size = msize - sizeof(struct m_hdr);
        m->m_data = m->m_dat;
        m->m_len = 0;
        m->m_nextpkt = 0;
        m->m_prevpkt = 0;
end_error:
        DEBUG_ARG("m = %lx", (long )m);
        return m;
}

void
m_free(m)
        struct mbuf *m;
{
        
  DEBUG_CALL("m_free");
  DEBUG_ARG("m = %lx", (long )m);
        
  if(m) {
        /* Remove from m_usedlist */
        if (m->m_flags & M_USEDLIST)
           remque(m);
        
        /* If it's M_EXT, free() it */
        if (m->m_flags & M_EXT)
           free(m->m_ext);

        /*
         * Either free() it or put it on the free list
         */
        if (m->m_flags & M_DOFREE) {
                free(m);
                mbuf_alloced--;
        } else if ((m->m_flags & M_FREELIST) == 0) {
                insque(m,&m_freelist);
                m->m_flags = M_FREELIST; /* Clobber other flags */
        }
  } /* if(m) */
}

/*
 * Copy data from one mbuf to the end of
 * the other.. if result is too big for one mbuf, malloc()
 * an M_EXT data segment
 */
void
m_cat(m, n)
        register struct mbuf *m, *n;
{
        /*
         * If there's no room, realloc
         */
        if (M_FREEROOM(m) < n->m_len)
                m_inc(m,m->m_size+MINCSIZE);
        
        memcpy(m->m_data+m->m_len, n->m_data, n->m_len);
        m->m_len += n->m_len;

        m_free(n);
}


/* make m size bytes large */
void
m_inc(m, size)
        struct mbuf *m;
        int size;
{
        /* some compiles throw up on gotos.  This one we can fake. */
        if(m->m_size>size) return;

        if (m->m_flags & M_EXT) {
          /* datasize = m->m_data - m->m_ext; */
          m->m_ext = (char *)realloc(m->m_ext,size);
/*              if (m->m_ext == NULL)
 *                      return (struct mbuf *)NULL;
 */             
          /* m->m_data = m->m_ext + datasize; */
        } else {
          int datasize;
          char *dat;
          datasize = m->m_data - m->m_dat;
          dat = (char *)malloc(size);
/*              if (dat == NULL)
 *                      return (struct mbuf *)NULL;
 */
          memcpy(dat, m->m_dat, m->m_size);
          
          m->m_ext = dat;
          m->m_data = m->m_ext + datasize;
          m->m_flags |= M_EXT;
        }
 
        m->m_size = size;

}


void
m_adj(m, len)
        struct mbuf *m;
        int len;
{
        if (m == NULL)
                return;
        if (len >= 0) {
                /* Trim from head */
                m->m_data += len;
                m->m_len -= len;
        } else {
                /* Trim from tail */
                len = -len;
                m->m_len -= len;
        }
}


/*
 * Copy len bytes from m, starting off bytes into n
 */
int
m_copy(n, m, off, len)
        struct mbuf *n, *m;
        int off, len;
{
        if (len > M_FREEROOM(n))
                return -1;

        memcpy((n->m_data + n->m_len), (m->m_data + off), len);
        n->m_len += len;
        return 0;
}


/*
 * Given a pointer into an mbuf, return the mbuf
 * XXX This is a kludge, I should eliminate the need for it
 * Fortunately, it's not used often
 */
struct mbuf *
dtom(dat)
        void *dat;
{
        struct mbuf *m;
        
        DEBUG_CALL("dtom");
        DEBUG_ARG("dat = %lx", (long )dat);

        /* bug corrected for M_EXT buffers */
        for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) {
          if (m->m_flags & M_EXT) {
            if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) )
              return m;
          } else {
            if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) )
              return m;
          }
        }
        
        DEBUG_ERROR((dfd, "dtom failed"));
        
        return (struct mbuf *)0;
}

Revision:	1.1
Committed:	2005-05-13T09:00:59Z (19 years, 4 months ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
CVS Tags:	nigel-build-17
Log Message:	slirp user mode network emulation code from qemu
#	User	Rev	Content
1	gbeauche	1.1	/*
2			* Copyright (c) 1995 Danny Gasparovski
3			*
4			* Please read the file COPYRIGHT for the
5			* terms and conditions of the copyright.
6			*/
7
8			/*
9			* mbuf's in SLiRP are much simpler than the real mbufs in
10			* FreeBSD. They are fixed size, determined by the MTU,
11			* so that one whole packet can fit. Mbuf's cannot be
12			* chained together. If there's more data than the mbuf
13			* could hold, an external malloced buffer is pointed to
14			* by m_ext (and the data pointers) and M_EXT is set in
15			* the flags
16			*/
17
18			#include <slirp.h>
19
20			struct mbuf *mbutl;
21			char *mclrefcnt;
22			int mbuf_alloced = 0;
23			struct mbuf m_freelist, m_usedlist;
24			int mbuf_thresh = 30;
25			int mbuf_max = 0;
26			int msize;
27
28			void
29			m_init()
30			{
31			m_freelist.m_next = m_freelist.m_prev = &m_freelist;
32			m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist;
33			msize_init();
34			}
35
36			void
37			msize_init()
38			{
39			/*
40			* Find a nice value for msize
41			* XXX if_maxlinkhdr already in mtu
42			*/
43			msize = (if_mtu>if_mru?if_mtu:if_mru) +
44			if_maxlinkhdr + sizeof(struct m_hdr ) + 6;
45			}
46
47			/*
48			* Get an mbuf from the free list, if there are none
49			* malloc one
50			*
51			* Because fragmentation can occur if we alloc new mbufs and
52			* free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE,
53			* which tells m_free to actually free() it
54			*/
55			struct mbuf *
56			m_get()
57			{
58			register struct mbuf *m;
59			int flags = 0;
60
61			DEBUG_CALL("m_get");
62
63			if (m_freelist.m_next == &m_freelist) {
64			m = (struct mbuf *)malloc(msize);
65			if (m == NULL) goto end_error;
66			mbuf_alloced++;
67			if (mbuf_alloced > mbuf_thresh)
68			flags = M_DOFREE;
69			if (mbuf_alloced > mbuf_max)
70			mbuf_max = mbuf_alloced;
71			} else {
72			m = m_freelist.m_next;
73			remque(m);
74			}
75
76			/* Insert it in the used list */
77			insque(m,&m_usedlist);
78			m->m_flags = (flags \| M_USEDLIST);
79
80			/* Initialise it */
81			m->m_size = msize - sizeof(struct m_hdr);
82			m->m_data = m->m_dat;
83			m->m_len = 0;
84			m->m_nextpkt = 0;
85			m->m_prevpkt = 0;
86			end_error:
87			DEBUG_ARG("m = %lx", (long )m);
88			return m;
89			}
90
91			void
92			m_free(m)
93			struct mbuf *m;
94			{
95
96			DEBUG_CALL("m_free");
97			DEBUG_ARG("m = %lx", (long )m);
98
99			if(m) {
100			/* Remove from m_usedlist */
101			if (m->m_flags & M_USEDLIST)
102			remque(m);
103
104			/* If it's M_EXT, free() it */
105			if (m->m_flags & M_EXT)
106			free(m->m_ext);
107
108			/*
109			* Either free() it or put it on the free list
110			*/
111			if (m->m_flags & M_DOFREE) {
112			free(m);
113			mbuf_alloced--;
114			} else if ((m->m_flags & M_FREELIST) == 0) {
115			insque(m,&m_freelist);
116			m->m_flags = M_FREELIST; /* Clobber other flags */
117			}
118			} /* if(m) */
119			}
120
121			/*
122			* Copy data from one mbuf to the end of
123			* the other.. if result is too big for one mbuf, malloc()
124			* an M_EXT data segment
125			*/
126			void
127			m_cat(m, n)
128			register struct mbuf m, n;
129			{
130			/*
131			* If there's no room, realloc
132			*/
133			if (M_FREEROOM(m) < n->m_len)
134			m_inc(m,m->m_size+MINCSIZE);
135
136			memcpy(m->m_data+m->m_len, n->m_data, n->m_len);
137			m->m_len += n->m_len;
138
139			m_free(n);
140			}
141
142
143			/* make m size bytes large */
144			void
145			m_inc(m, size)
146			struct mbuf *m;
147			int size;
148			{
149			/* some compiles throw up on gotos. This one we can fake. */
150			if(m->m_size>size) return;
151
152			if (m->m_flags & M_EXT) {
153			/* datasize = m->m_data - m->m_ext; */
154			m->m_ext = (char *)realloc(m->m_ext,size);
155			/* if (m->m_ext == NULL)
156			* return (struct mbuf *)NULL;
157			*/
158			/* m->m_data = m->m_ext + datasize; */
159			} else {
160			int datasize;
161			char *dat;
162			datasize = m->m_data - m->m_dat;
163			dat = (char *)malloc(size);
164			/* if (dat == NULL)
165			* return (struct mbuf *)NULL;
166			*/
167			memcpy(dat, m->m_dat, m->m_size);
168
169			m->m_ext = dat;
170			m->m_data = m->m_ext + datasize;
171			m->m_flags \|= M_EXT;
172			}
173
174			m->m_size = size;
175
176			}
177
178
179
180			void
181			m_adj(m, len)
182			struct mbuf *m;
183			int len;
184			{
185			if (m == NULL)
186			return;
187			if (len >= 0) {
188			/* Trim from head */
189			m->m_data += len;
190			m->m_len -= len;
191			} else {
192			/* Trim from tail */
193			len = -len;
194			m->m_len -= len;
195			}
196			}
197
198
199			/*
200			* Copy len bytes from m, starting off bytes into n
201			*/
202			int
203			m_copy(n, m, off, len)
204			struct mbuf n, m;
205			int off, len;
206			{
207			if (len > M_FREEROOM(n))
208			return -1;
209
210			memcpy((n->m_data + n->m_len), (m->m_data + off), len);
211			n->m_len += len;
212			return 0;
213			}
214
215
216			/*
217			* Given a pointer into an mbuf, return the mbuf
218			* XXX This is a kludge, I should eliminate the need for it
219			* Fortunately, it's not used often
220			*/
221			struct mbuf *
222			dtom(dat)
223			void *dat;
224			{
225			struct mbuf *m;
226
227			DEBUG_CALL("dtom");
228			DEBUG_ARG("dat = %lx", (long )dat);
229
230			/* bug corrected for M_EXT buffers */
231			for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) {
232			if (m->m_flags & M_EXT) {
233			if( (char )dat>=m->m_ext && (char )dat<(m->m_ext + m->m_size) )
234			return m;
235			} else {
236			if( (char )dat >= m->m_dat && (char )dat<(m->m_dat + m->m_size) )
237			return m;
238			}
239			}
240
241			DEBUG_ERROR((dfd, "dtom failed"));
242
243			return (struct mbuf *)0;
244			}
245