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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>
46 #include <sys/socket.h>
47 #include <sys/sockio.h>
49 #include <sys/mplock2.h>
52 #include <net/if_types.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 void loopattach(void *);
73 static int looutput(struct ifnet *, struct mbuf *, struct sockaddr *,
75 static int loioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
76 static void lortrequest(int, struct rtentry *);
78 static void lo_altqstart(struct ifnet *, struct ifaltq_subque *);
80 PSEUDO_SET(loopattach, if_loop);
83 #define LOMTU (1024+512)
84 #elif defined(LARGE_LOMTU)
90 #define LO_CSUM_FEATURES (CSUM_IP | CSUM_UDP | CSUM_TCP)
92 struct ifnet loif[NLOOP];
96 loopattach(void *dummy)
101 for (i = 0, ifp = loif; i < NLOOP; i++, ifp++) {
102 if_initname(ifp, "lo", i);
104 ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
105 ifp->if_capabilities = IFCAP_HWCSUM | IFCAP_RSS;
106 ifp->if_hwassist = LO_CSUM_FEATURES;
107 ifp->if_capenable = ifp->if_capabilities;
108 ifp->if_ioctl = loioctl;
109 ifp->if_output = looutput;
110 ifp->if_type = IFT_LOOP;
111 ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
112 ifq_set_ready(&ifp->if_snd);
114 ifp->if_start = lo_altqstart;
116 if_attach(ifp, NULL);
117 bpfattach(ifp, DLT_NULL, sizeof(u_int));
122 looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
127 if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
129 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
130 rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
133 IFNET_STAT_INC(ifp, opackets, 1);
134 IFNET_STAT_INC(ifp, obytes, m->m_pkthdr.len);
136 switch (dst->sa_family) {
141 kprintf("looutput: af=%d unexpected\n", dst->sa_family);
143 return (EAFNOSUPPORT);
147 if (ifp->if_capenable & IFCAP_RXCSUM) {
150 if (m->m_pkthdr.csum_flags & CSUM_IP)
151 csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
152 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
153 csum_flags |= (CSUM_DATA_VALID | CSUM_PSEUDO_HDR);
155 m->m_pkthdr.csum_flags |= csum_flags;
156 if (csum_flags & CSUM_DATA_VALID)
157 m->m_pkthdr.csum_data = 0xffff;
159 if ((ifp->if_capenable & IFCAP_RSS) == 0)
160 m->m_flags &= ~M_HASH;
161 return (if_simloop(ifp, m, dst->sa_family, 0));
167 * This function is to support software emulation of hardware loopback,
168 * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
169 * hear their own broadcasts, we create a copy of the packet that we
170 * would normally receive via a hardware loopback.
172 * This function expects the packet to include the media header of length hlen.
175 if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
179 KASSERT((m->m_flags & M_PKTHDR) != 0, ("if_simloop: no HDR"));
180 m->m_pkthdr.rcvif = ifp;
182 /* BPF write needs to be handled specially */
183 if (af == AF_UNSPEC) {
184 KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
185 af = *(mtod(m, int *));
186 m->m_len -= sizeof(int);
187 m->m_pkthdr.len -= sizeof(int);
188 m->m_data += sizeof(int);
195 if (ifp->if_bpf == NULL)
198 if (ifp->if_bpf->bif_dlt == DLT_NULL) {
199 uint32_t bpf_af = (uint32_t)af;
200 bpf_ptap(ifp->if_bpf, m, &bpf_af, 4);
202 bpf_mtap(ifp->if_bpf, m);
208 /* Strip away media header */
214 * altq for loop is just for debugging.
215 * only used when called for loop interface (not for
216 * a simplex interface).
218 if (ifq_is_enabled(&ifp->if_snd) && ifp->if_start == lo_altqstart) {
219 struct altq_pktattr pktattr;
223 * if the queueing discipline needs packet classification,
224 * do it before prepending link headers.
226 ifq_classify(&ifp->if_snd, m, af, &pktattr);
228 M_PREPEND(m, sizeof(int32_t), M_NOWAIT);
231 afp = mtod(m, int32_t *);
234 return ifq_dispatch(ifp, m, &pktattr);
238 /* Deliver to upper layer protocol */
247 m->m_flags |= M_LOOP;
252 kprintf("if_simloop: can't handle af=%d\n", af);
254 return (EAFNOSUPPORT);
257 IFNET_STAT_INC(ifp, ipackets, 1);
258 IFNET_STAT_INC(ifp, ibytes, m->m_pkthdr.len);
259 netisr_queue(isr, m);
265 lo_altqstart(struct ifnet *ifp, struct ifaltq_subque *ifsq)
273 m = ifsq_dequeue(ifsq);
278 afp = mtod(m, int32_t *);
280 m_adj(m, sizeof(int32_t));
290 m->m_flags |= M_LOOP;
295 kprintf("lo_altqstart: can't handle af%d\n", af);
300 IFNET_STAT_INC(ifp, ipackets, 1);
301 IFNET_STAT_INC(ifp, ibytes, m->m_pkthdr.len);
302 netisr_queue(isr, m);
309 lortrequest(int cmd, struct rtentry *rt)
312 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; /* for ISO */
314 * For optimal performance, the send and receive buffers
315 * should be at least twice the MTU plus a little more for
318 rt->rt_rmx.rmx_recvpipe = rt->rt_rmx.rmx_sendpipe = 3 * LOMTU;
323 * Process an ioctl request.
327 loioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
330 struct ifreq *ifr = (struct ifreq *)data;
335 ifp->if_flags |= IFF_UP | IFF_RUNNING;
336 ifa = (struct ifaddr *)data;
337 ifa->ifa_rtrequest = lortrequest;
339 * Everything else is done at a higher level.
346 error = EAFNOSUPPORT; /* XXX */
349 switch (ifr->ifr_addr.sa_family) {
361 error = EAFNOSUPPORT;
367 ifp->if_mtu = ifr->ifr_mtu;
374 mask = ifr->ifr_reqcap ^ ifp->if_capenable;
375 if (mask & IFCAP_HWCSUM) {
376 ifp->if_capenable ^= (mask & IFCAP_HWCSUM);
377 if (IFCAP_TXCSUM & ifp->if_capenable)
378 ifp->if_hwassist = LO_CSUM_FEATURES;
380 ifp->if_hwassist = 0;
382 if (mask & IFCAP_RSS)
383 ifp->if_capenable ^= IFCAP_RSS;