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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 $
35 * $DragonFly: src/sys/net/if_loop.c,v 1.26 2008/10/04 11:21:10 sephe Exp $
39 * Loopback interface driver for protocol testing and timing.
43 #include "opt_atalk.h"
45 #include "opt_inet6.h"
48 #include <sys/param.h>
49 #include <sys/systm.h>
50 #include <sys/kernel.h>
53 #include <sys/socket.h>
54 #include <sys/sockio.h>
56 #include <sys/mplock2.h>
59 #include <net/if_types.h>
60 #include <net/ifq_var.h>
61 #include <net/netisr.h>
62 #include <net/route.h>
64 #include <net/bpfdesc.h>
67 #include <netinet/in.h>
68 #include <netinet/in_var.h>
72 #include <netproto/ipx/ipx.h>
73 #include <netproto/ipx/ipx_if.h>
78 #include <netinet/in.h>
80 #include <netinet6/in6_var.h>
81 #include <netinet/ip6.h>
86 #include <netns/ns_if.h>
90 #include <netproto/atalk/at.h>
91 #include <netproto/atalk/at_var.h>
94 static void loopattach(void *);
95 static int looutput(struct ifnet *, struct mbuf *, struct sockaddr *,
97 static int loioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
98 static void lortrequest(int, struct rtentry *, struct rt_addrinfo *);
100 static void lo_altqstart(struct ifnet *);
102 PSEUDO_SET(loopattach, if_loop);
105 #define LOMTU (1024+512)
106 #elif defined(LARGE_LOMTU)
112 #define LO_CSUM_FEATURES (CSUM_IP | CSUM_UDP | CSUM_TCP)
114 struct ifnet loif[NLOOP];
118 loopattach(void *dummy)
123 for (i = 0, ifp = loif; i < NLOOP; i++, ifp++) {
124 if_initname(ifp, "lo", i);
126 ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
127 ifp->if_capabilities = IFCAP_HWCSUM;
128 ifp->if_hwassist = LO_CSUM_FEATURES;
129 ifp->if_capenable = ifp->if_capabilities;
130 ifp->if_ioctl = loioctl;
131 ifp->if_output = looutput;
132 ifp->if_type = IFT_LOOP;
133 ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
134 ifq_set_ready(&ifp->if_snd);
136 ifp->if_start = lo_altqstart;
138 if_attach(ifp, NULL);
139 bpfattach(ifp, DLT_NULL, sizeof(u_int));
144 looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
149 if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
151 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
152 rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
156 ifp->if_obytes += m->m_pkthdr.len;
158 switch (dst->sa_family) {
166 kprintf("looutput: af=%d unexpected\n", dst->sa_family);
168 return (EAFNOSUPPORT);
172 if (ifp->if_capenable & IFCAP_RXCSUM) {
175 if (m->m_pkthdr.csum_flags & CSUM_IP)
176 csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
177 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
178 csum_flags |= (CSUM_DATA_VALID | CSUM_PSEUDO_HDR);
180 m->m_pkthdr.csum_flags |= csum_flags;
181 if (csum_flags & CSUM_DATA_VALID)
182 m->m_pkthdr.csum_data = 0xffff;
184 return (if_simloop(ifp, m, dst->sa_family, 0));
190 * This function is to support software emulation of hardware loopback,
191 * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
192 * hear their own broadcasts, we create a copy of the packet that we
193 * would normally receive via a hardware loopback.
195 * This function expects the packet to include the media header of length hlen.
198 if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
202 KASSERT((m->m_flags & M_PKTHDR) != 0, ("if_simloop: no HDR"));
203 m->m_pkthdr.rcvif = ifp;
205 /* BPF write needs to be handled specially */
206 if (af == AF_UNSPEC) {
207 KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
208 af = *(mtod(m, int *));
209 m->m_len -= sizeof(int);
210 m->m_pkthdr.len -= sizeof(int);
211 m->m_data += sizeof(int);
218 if (ifp->if_bpf == NULL)
221 if (ifp->if_bpf->bif_dlt == DLT_NULL) {
222 uint32_t bpf_af = (uint32_t)af;
223 bpf_ptap(ifp->if_bpf, m, &bpf_af, 4);
225 bpf_mtap(ifp->if_bpf, m);
231 /* Strip away media header */
237 * altq for loop is just for debugging.
238 * only used when called for loop interface (not for
239 * a simplex interface).
241 if (ifq_is_enabled(&ifp->if_snd) && ifp->if_start == lo_altqstart) {
242 struct altq_pktattr pktattr;
247 * if the queueing discipline needs packet classification,
248 * do it before prepending link headers.
250 ifq_classify(&ifp->if_snd, m, af, &pktattr);
252 M_PREPEND(m, sizeof(int32_t), MB_DONTWAIT);
255 afp = mtod(m, int32_t *);
259 * A critical section is needed for subsystems protected by
260 * the MP lock, and the serializer is assumed to already
261 * be held for MPSAFE subsystems.
264 error = ifq_enqueue(&ifp->if_snd, m, &pktattr);
265 ifnet_serialize_tx(ifp);
267 ifnet_deserialize_tx(ifp);
273 /* Deliver to upper layer protocol */
282 m->m_flags |= M_LOOP;
302 kprintf("if_simloop: can't handle af=%d\n", af);
304 return (EAFNOSUPPORT);
308 ifp->if_ibytes += m->m_pkthdr.len;
309 netisr_queue(isr, m);
315 lo_altqstart(struct ifnet *ifp)
323 m = ifq_dequeue(&ifp->if_snd, NULL);
328 afp = mtod(m, int32_t *);
330 m_adj(m, sizeof(int32_t));
340 m->m_flags |= M_LOOP;
365 kprintf("lo_altqstart: can't handle af%d\n", af);
371 ifp->if_ibytes += m->m_pkthdr.len;
372 netisr_queue(isr, m);
379 lortrequest(int cmd, struct rtentry *rt, struct rt_addrinfo *info)
382 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; /* for ISO */
384 * For optimal performance, the send and receive buffers
385 * should be at least twice the MTU plus a little more for
388 rt->rt_rmx.rmx_recvpipe = rt->rt_rmx.rmx_sendpipe = 3 * LOMTU;
393 * Process an ioctl request.
397 loioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
400 struct ifreq *ifr = (struct ifreq *)data;
405 ifp->if_flags |= IFF_UP | IFF_RUNNING;
406 ifa = (struct ifaddr *)data;
407 ifa->ifa_rtrequest = lortrequest;
409 * Everything else is done at a higher level.
416 error = EAFNOSUPPORT; /* XXX */
419 switch (ifr->ifr_addr.sa_family) {
431 error = EAFNOSUPPORT;
437 ifp->if_mtu = ifr->ifr_mtu;
444 mask = (ifr->ifr_reqcap ^ ifp->if_capenable) & IFCAP_HWCSUM;
446 ifp->if_capenable ^= mask;
447 if (IFCAP_TXCSUM & ifp->if_capenable)
448 ifp->if_hwassist = LO_CSUM_FEATURES;
450 ifp->if_hwassist = 0;