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29 * @(#)if_loop.c 8.1 (Berkeley) 6/10/93
30 * $FreeBSD: src/sys/net/if_loop.c,v 1.47.2.9 2004/02/08 08:40:24 silby Exp $
34 * Loopback interface driver for protocol testing and timing.
39 #include "opt_inet6.h"
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/kernel.h>
45 #include <sys/malloc.h>
47 #include <sys/socket.h>
48 #include <sys/sockio.h>
51 #include <net/if_types.h>
52 #include <net/if_clone.h>
53 #include <net/ifq_var.h>
54 #include <net/netisr.h>
55 #include <net/route.h>
57 #include <net/bpfdesc.h>
60 #include <netinet/in.h>
61 #include <netinet/in_var.h>
66 #include <netinet/in.h>
68 #include <netinet6/in6_var.h>
69 #include <netinet/ip6.h>
72 static int lo_clone_create(struct if_clone *, int, caddr_t);
73 static int lo_clone_destroy(struct ifnet *);
75 static int lo_output(struct ifnet *, struct mbuf *, struct sockaddr *,
77 static int lo_ioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
78 static void lo_rtrequest(int, struct rtentry *);
80 static void lo_altqstart(struct ifnet *, struct ifaltq_subque *);
83 #if defined(TINY_LOMTU)
84 #define LOMTU (1024+512)
85 #elif defined(LARGE_LOMTU)
91 #define LO_CSUM_FEATURES (CSUM_IP | CSUM_UDP | CSUM_TCP)
95 static struct if_clone lo_cloner = IF_CLONE_INITIALIZER("lo",
96 lo_clone_create, lo_clone_destroy, NLOOP, IF_MAXUNIT);
99 lo_sysinit(void *dummy __unused)
101 if_clone_attach(&lo_cloner);
103 SYSINIT(lo_sysinit, SI_SUB_PSEUDO, SI_ORDER_ANY, lo_sysinit, NULL);
106 lo_clone_create(struct if_clone *ifc, int unit, caddr_t param __unused)
110 ifp = kmalloc(sizeof(*ifp), M_IFNET, M_WAITOK | M_ZERO);
111 if_initname(ifp, ifc->ifc_name, unit);
113 ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
114 ifp->if_capabilities = IFCAP_HWCSUM | IFCAP_RSS;
115 ifp->if_hwassist = LO_CSUM_FEATURES;
116 ifp->if_capenable = ifp->if_capabilities;
117 ifp->if_ioctl = lo_ioctl;
118 ifp->if_output = lo_output;
119 ifp->if_type = IFT_LOOP;
120 ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
121 ifq_set_ready(&ifp->if_snd);
123 ifp->if_start = lo_altqstart;
125 if_attach(ifp, NULL);
126 bpfattach(ifp, DLT_NULL, sizeof(u_int));
129 KASSERT(unit == 0, ("loif is %s", ifp->if_xname));
136 lo_clone_destroy(struct ifnet *ifp)
148 lo_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
153 if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
155 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
156 rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
159 IFNET_STAT_INC(ifp, opackets, 1);
160 IFNET_STAT_INC(ifp, obytes, m->m_pkthdr.len);
162 switch (dst->sa_family) {
167 kprintf("lo_output: af=%d unexpected\n", dst->sa_family);
169 return (EAFNOSUPPORT);
173 if (ifp->if_capenable & IFCAP_RXCSUM) {
176 if (m->m_pkthdr.csum_flags & CSUM_IP)
177 csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
178 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
179 csum_flags |= (CSUM_DATA_VALID | CSUM_PSEUDO_HDR);
181 m->m_pkthdr.csum_flags |= csum_flags;
182 if (csum_flags & CSUM_DATA_VALID)
183 m->m_pkthdr.csum_data = 0xffff;
185 if ((ifp->if_capenable & IFCAP_RSS) == 0)
186 m->m_flags &= ~M_HASH;
187 return (if_simloop(ifp, m, dst->sa_family, 0));
193 * This function is to support software emulation of hardware loopback,
194 * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
195 * hear their own broadcasts, we create a copy of the packet that we
196 * would normally receive via a hardware loopback.
198 * This function expects the packet to include the media header of length hlen.
201 if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
205 KASSERT((m->m_flags & M_PKTHDR) != 0, ("if_simloop: no HDR"));
206 m->m_pkthdr.rcvif = ifp;
208 /* BPF write needs to be handled specially */
209 if (af == AF_UNSPEC) {
210 KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
211 af = *(mtod(m, int *));
212 m->m_len -= sizeof(int);
213 m->m_pkthdr.len -= sizeof(int);
214 m->m_data += sizeof(int);
221 if (ifp->if_bpf == NULL)
224 if (ifp->if_bpf->bif_dlt == DLT_NULL) {
225 uint32_t bpf_af = (uint32_t)af;
226 bpf_ptap(ifp->if_bpf, m, &bpf_af, 4);
228 bpf_mtap(ifp->if_bpf, m);
234 /* Strip away media header */
240 * altq for loop is just for debugging.
241 * only used when called for loop interface (not for
242 * a simplex interface).
244 if (ifq_is_enabled(&ifp->if_snd) && ifp->if_start == lo_altqstart) {
245 struct altq_pktattr pktattr;
249 * if the queueing discipline needs packet classification,
250 * do it before prepending link headers.
252 ifq_classify(&ifp->if_snd, m, af, &pktattr);
254 M_PREPEND(m, sizeof(int32_t), M_NOWAIT);
257 afp = mtod(m, int32_t *);
260 return ifq_dispatch(ifp, m, &pktattr);
264 /* Deliver to upper layer protocol */
273 m->m_flags |= M_LOOP;
278 kprintf("if_simloop: can't handle af=%d\n", af);
280 return (EAFNOSUPPORT);
283 IFNET_STAT_INC(ifp, ipackets, 1);
284 IFNET_STAT_INC(ifp, ibytes, m->m_pkthdr.len);
285 netisr_queue(isr, m);
291 lo_altqstart(struct ifnet *ifp, struct ifaltq_subque *ifsq)
299 m = ifsq_dequeue(ifsq);
304 afp = mtod(m, int32_t *);
306 m_adj(m, sizeof(int32_t));
316 m->m_flags |= M_LOOP;
321 kprintf("lo_altqstart: can't handle af%d\n", af);
326 IFNET_STAT_INC(ifp, ipackets, 1);
327 IFNET_STAT_INC(ifp, ibytes, m->m_pkthdr.len);
328 netisr_queue(isr, m);
335 lo_rtrequest(int cmd, struct rtentry *rt)
338 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; /* for ISO */
340 * For optimal performance, the send and receive buffers
341 * should be at least twice the MTU plus a little more for
344 rt->rt_rmx.rmx_recvpipe = rt->rt_rmx.rmx_sendpipe = 3 * LOMTU;
349 * Process an ioctl request.
353 lo_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
356 struct ifreq *ifr = (struct ifreq *)data;
361 ifp->if_flags |= IFF_UP | IFF_RUNNING;
362 ifa = (struct ifaddr *)data;
363 ifa->ifa_rtrequest = lo_rtrequest;
365 * Everything else is done at a higher level.
372 error = EAFNOSUPPORT; /* XXX */
375 switch (ifr->ifr_addr.sa_family) {
387 error = EAFNOSUPPORT;
393 ifp->if_mtu = ifr->ifr_mtu;
400 mask = ifr->ifr_reqcap ^ ifp->if_capenable;
401 if (mask & IFCAP_HWCSUM) {
402 ifp->if_capenable ^= (mask & IFCAP_HWCSUM);
403 if (IFCAP_TXCSUM & ifp->if_capenable)
404 ifp->if_hwassist = LO_CSUM_FEATURES;
406 ifp->if_hwassist = 0;
408 if (mask & IFCAP_RSS)
409 ifp->if_capenable ^= IFCAP_RSS;