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33 * @(#)if_loop.c 8.1 (Berkeley) 6/10/93
34 * $FreeBSD: src/sys/net/if_loop.c,v 1.47.2.9 2004/02/08 08:40:24 silby Exp $
38 * Loopback interface driver for protocol testing and timing.
43 #include "opt_inet6.h"
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
51 #include <sys/socket.h>
52 #include <sys/sockio.h>
54 #include <sys/mplock2.h>
57 #include <net/if_types.h>
58 #include <net/ifq_var.h>
59 #include <net/netisr.h>
60 #include <net/route.h>
62 #include <net/bpfdesc.h>
65 #include <netinet/in.h>
66 #include <netinet/in_var.h>
70 #include <netproto/ipx/ipx.h>
71 #include <netproto/ipx/ipx_if.h>
76 #include <netinet/in.h>
78 #include <netinet6/in6_var.h>
79 #include <netinet/ip6.h>
82 static void loopattach(void *);
83 static int looutput(struct ifnet *, struct mbuf *, struct sockaddr *,
85 static int loioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
86 static void lortrequest(int, struct rtentry *, struct rt_addrinfo *);
88 static void lo_altqstart(struct ifnet *);
90 PSEUDO_SET(loopattach, if_loop);
93 #define LOMTU (1024+512)
94 #elif defined(LARGE_LOMTU)
100 #define LO_CSUM_FEATURES (CSUM_IP | CSUM_UDP | CSUM_TCP)
102 struct ifnet loif[NLOOP];
106 loopattach(void *dummy)
111 for (i = 0, ifp = loif; i < NLOOP; i++, ifp++) {
112 if_initname(ifp, "lo", i);
114 ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
115 ifp->if_capabilities = IFCAP_HWCSUM;
116 ifp->if_hwassist = LO_CSUM_FEATURES;
117 ifp->if_capenable = ifp->if_capabilities;
118 ifp->if_ioctl = loioctl;
119 ifp->if_output = looutput;
120 ifp->if_type = IFT_LOOP;
121 ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
122 ifq_set_ready(&ifp->if_snd);
124 ifp->if_start = lo_altqstart;
126 if_attach(ifp, NULL);
127 bpfattach(ifp, DLT_NULL, sizeof(u_int));
132 looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
137 if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
139 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
140 rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
144 ifp->if_obytes += m->m_pkthdr.len;
146 switch (dst->sa_family) {
153 kprintf("looutput: af=%d unexpected\n", dst->sa_family);
155 return (EAFNOSUPPORT);
159 if (ifp->if_capenable & IFCAP_RXCSUM) {
162 if (m->m_pkthdr.csum_flags & CSUM_IP)
163 csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
164 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
165 csum_flags |= (CSUM_DATA_VALID | CSUM_PSEUDO_HDR);
167 m->m_pkthdr.csum_flags |= csum_flags;
168 if (csum_flags & CSUM_DATA_VALID)
169 m->m_pkthdr.csum_data = 0xffff;
171 return (if_simloop(ifp, m, dst->sa_family, 0));
177 * This function is to support software emulation of hardware loopback,
178 * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
179 * hear their own broadcasts, we create a copy of the packet that we
180 * would normally receive via a hardware loopback.
182 * This function expects the packet to include the media header of length hlen.
185 if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
189 KASSERT((m->m_flags & M_PKTHDR) != 0, ("if_simloop: no HDR"));
190 m->m_pkthdr.rcvif = ifp;
192 /* BPF write needs to be handled specially */
193 if (af == AF_UNSPEC) {
194 KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
195 af = *(mtod(m, int *));
196 m->m_len -= sizeof(int);
197 m->m_pkthdr.len -= sizeof(int);
198 m->m_data += sizeof(int);
205 if (ifp->if_bpf == NULL)
208 if (ifp->if_bpf->bif_dlt == DLT_NULL) {
209 uint32_t bpf_af = (uint32_t)af;
210 bpf_ptap(ifp->if_bpf, m, &bpf_af, 4);
212 bpf_mtap(ifp->if_bpf, m);
218 /* Strip away media header */
224 * altq for loop is just for debugging.
225 * only used when called for loop interface (not for
226 * a simplex interface).
228 if (ifq_is_enabled(&ifp->if_snd) && ifp->if_start == lo_altqstart) {
229 struct altq_pktattr pktattr;
234 * if the queueing discipline needs packet classification,
235 * do it before prepending link headers.
237 ifq_classify(&ifp->if_snd, m, af, &pktattr);
239 M_PREPEND(m, sizeof(int32_t), MB_DONTWAIT);
242 afp = mtod(m, int32_t *);
246 * A critical section is needed for subsystems protected by
247 * the MP lock, and the serializer is assumed to already
248 * be held for MPSAFE subsystems.
251 error = ifq_enqueue(&ifp->if_snd, m, &pktattr);
252 ifnet_serialize_tx(ifp);
254 ifnet_deserialize_tx(ifp);
260 /* Deliver to upper layer protocol */
269 m->m_flags |= M_LOOP;
279 kprintf("if_simloop: can't handle af=%d\n", af);
281 return (EAFNOSUPPORT);
285 ifp->if_ibytes += m->m_pkthdr.len;
286 netisr_queue(isr, m);
292 lo_altqstart(struct ifnet *ifp)
300 m = ifq_dequeue(&ifp->if_snd, NULL);
305 afp = mtod(m, int32_t *);
307 m_adj(m, sizeof(int32_t));
317 m->m_flags |= M_LOOP;
332 kprintf("lo_altqstart: can't handle af%d\n", af);
338 ifp->if_ibytes += m->m_pkthdr.len;
339 netisr_queue(isr, m);
346 lortrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
349 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; /* for ISO */
351 * For optimal performance, the send and receive buffers
352 * should be at least twice the MTU plus a little more for
355 rt->rt_rmx.rmx_recvpipe = rt->rt_rmx.rmx_sendpipe = 3 * LOMTU;
360 * Process an ioctl request.
364 loioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
367 struct ifreq *ifr = (struct ifreq *)data;
372 ifp->if_flags |= IFF_UP | IFF_RUNNING;
373 ifa = (struct ifaddr *)data;
374 ifa->ifa_rtrequest = lortrequest;
376 * Everything else is done at a higher level.
383 error = EAFNOSUPPORT; /* XXX */
386 switch (ifr->ifr_addr.sa_family) {
398 error = EAFNOSUPPORT;
404 ifp->if_mtu = ifr->ifr_mtu;
411 mask = (ifr->ifr_reqcap ^ ifp->if_capenable) & IFCAP_HWCSUM;
413 ifp->if_capenable ^= mask;
414 if (IFCAP_TXCSUM & ifp->if_capenable)
415 ifp->if_hwassist = LO_CSUM_FEATURES;
417 ifp->if_hwassist = 0;