1 /* SPDX-License-Identifier: BSD-3-Clause */
2 /*
3 * Copyright (c) 2013
4 * Guillaume Subiron
5 */
6
7 #include "slirp.h"
8 #include "udp.h"
9 #include "dhcpv6.h"
10
udp6_input(struct mbuf * m)11 void udp6_input(struct mbuf *m)
12 {
13 Slirp *slirp = m->slirp;
14 M_DUP_DEBUG(slirp, m, 0, 0);
15
16 struct ip6 *ip, save_ip;
17 struct udphdr *uh;
18 int iphlen = sizeof(struct ip6);
19 int len;
20 struct socket *so;
21 struct sockaddr_in6 lhost;
22 int hop_limit;
23
24 DEBUG_CALL("udp6_input");
25 DEBUG_ARG("m = %p", m);
26
27 if (slirp->restricted) {
28 goto bad;
29 }
30
31 ip = mtod(m, struct ip6 *);
32 m->m_len -= iphlen;
33 m->m_data += iphlen;
34 uh = mtod_check(m, sizeof(struct udphdr));
35 if (uh == NULL) {
36 goto bad;
37 }
38 m->m_len += iphlen;
39 m->m_data -= iphlen;
40
41 if (ip6_cksum(m)) {
42 goto bad;
43 }
44
45 len = ntohs((uint16_t)uh->uh_ulen);
46
47 /*
48 * Make mbuf data length reflect UDP length.
49 * If not enough data to reflect UDP length, drop.
50 */
51 if (ntohs(ip->ip_pl) != len) {
52 if (len > ntohs(ip->ip_pl)) {
53 goto bad;
54 }
55 m_adj(m, len - ntohs(ip->ip_pl));
56 ip->ip_pl = htons(len);
57 }
58
59 /*
60 * Save a copy of the IP header in case we want restore it
61 * for sending an ICMP error message in response.
62 */
63 save_ip = *ip;
64
65 /* Locate pcb for datagram. */
66 lhost.sin6_family = AF_INET6;
67 lhost.sin6_addr = ip->ip_src;
68 lhost.sin6_port = uh->uh_sport;
69
70 /* handle DHCPv6 */
71 if (ntohs(uh->uh_dport) == DHCPV6_SERVER_PORT &&
72 (in6_equal(&ip->ip_dst, &slirp->vhost_addr6) ||
73 in6_dhcp_multicast(&ip->ip_dst))) {
74 m->m_data += iphlen;
75 m->m_len -= iphlen;
76 dhcpv6_input(&lhost, m);
77 m->m_data -= iphlen;
78 m->m_len += iphlen;
79 goto bad;
80 }
81
82 /* handle TFTP */
83 if (ntohs(uh->uh_dport) == TFTP_SERVER &&
84 !memcmp(ip->ip_dst.s6_addr, slirp->vhost_addr6.s6_addr, 16)) {
85 m->m_data += iphlen;
86 m->m_len -= iphlen;
87 tftp_input((struct sockaddr_storage *)&lhost, m);
88 m->m_data -= iphlen;
89 m->m_len += iphlen;
90 goto bad;
91 }
92
93 so = solookup(&slirp->udp_last_so, &slirp->udb,
94 (struct sockaddr_storage *)&lhost, NULL);
95
96 if (so == NULL) {
97 /* If there's no socket for this packet, create one. */
98 so = socreate(slirp);
99 if (udp_attach(so, AF_INET6) == -1) {
100 DEBUG_MISC(" udp6_attach errno = %d-%s", errno, strerror(errno));
101 sofree(so);
102 goto bad;
103 }
104
105 /* Setup fields */
106 so->so_lfamily = AF_INET6;
107 so->so_laddr6 = ip->ip_src;
108 so->so_lport6 = uh->uh_sport;
109 }
110
111 so->so_ffamily = AF_INET6;
112 so->so_faddr6 = ip->ip_dst; /* XXX */
113 so->so_fport6 = uh->uh_dport; /* XXX */
114
115 iphlen += sizeof(struct udphdr);
116 m->m_len -= iphlen;
117 m->m_data += iphlen;
118
119 /*
120 * Check for TTL
121 */
122 hop_limit = save_ip.ip_hl-1;
123 if (hop_limit <= 0) {
124 m->m_len += iphlen;
125 m->m_data -= iphlen;
126 *ip = save_ip;
127 DEBUG_MISC("udp ttl exceeded");
128 icmp6_send_error(m, ICMP6_TIMXCEED, ICMP6_TIMXCEED_INTRANS);
129 goto bad;
130 }
131 setsockopt(so->s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hop_limit, sizeof(hop_limit));
132
133 /*
134 * Now we sendto() the packet.
135 */
136 if (sosendto(so, m) == -1) {
137 m->m_len += iphlen;
138 m->m_data -= iphlen;
139 *ip = save_ip;
140 DEBUG_MISC("udp tx errno = %d-%s", errno, strerror(errno));
141 icmp6_send_error(m, ICMP6_UNREACH, ICMP6_UNREACH_NO_ROUTE);
142 goto bad;
143 }
144
145 m_free(so->so_m); /* used for ICMP if error on sorecvfrom */
146
147 /* restore the orig mbuf packet */
148 m->m_len += iphlen;
149 m->m_data -= iphlen;
150 *ip = save_ip;
151 so->so_m = m;
152
153 return;
154 bad:
155 m_free(m);
156 }
157
udp6_output(struct socket * so,struct mbuf * m,struct sockaddr_in6 * saddr,struct sockaddr_in6 * daddr)158 int udp6_output(struct socket *so, struct mbuf *m, struct sockaddr_in6 *saddr,
159 struct sockaddr_in6 *daddr)
160 {
161 Slirp *slirp = m->slirp;
162 M_DUP_DEBUG(slirp, m, 0, sizeof(struct ip6) + sizeof(struct udphdr));
163
164 struct ip6 *ip;
165 struct udphdr *uh;
166
167 DEBUG_CALL("udp6_output");
168 DEBUG_ARG("so = %p", so);
169 DEBUG_ARG("m = %p", m);
170
171 /* adjust for header */
172 m->m_data -= sizeof(struct udphdr);
173 m->m_len += sizeof(struct udphdr);
174 uh = mtod(m, struct udphdr *);
175 m->m_data -= sizeof(struct ip6);
176 m->m_len += sizeof(struct ip6);
177 ip = mtod(m, struct ip6 *);
178
179 /* Build IP header */
180 ip->ip_pl = htons(m->m_len - sizeof(struct ip6));
181 ip->ip_nh = IPPROTO_UDP;
182 ip->ip_src = saddr->sin6_addr;
183 ip->ip_dst = daddr->sin6_addr;
184
185 /* Build UDP header */
186 uh->uh_sport = saddr->sin6_port;
187 uh->uh_dport = daddr->sin6_port;
188 uh->uh_ulen = ip->ip_pl;
189 uh->uh_sum = 0;
190 uh->uh_sum = ip6_cksum(m);
191 if (uh->uh_sum == 0) {
192 uh->uh_sum = 0xffff;
193 }
194
195 return ip6_output(so, m, 0);
196 }
197