udp_input(register struct mbuf *m, int iphlen) { Slirp *slirp = m->slirp; register struct ip *ip; register struct udphdr *uh; int len; struct ip save_ip; struct socket *so; DEBUG_CALL("udp_input"); DEBUG_ARG("m = %lx", (long)m); DEBUG_ARG("iphlen = %d", iphlen); /* * Strip IP options, if any; should skip this, * make available to user, and use on returned packets, * but we don't yet have a way to check the checksum * with options still present. */ if(iphlen > sizeof(struct ip)) { ip_stripoptions(m, (struct mbuf *)0); iphlen = sizeof(struct ip); } /* * Get IP and UDP header together in first mbuf. */ ip = mtod(m, struct ip *); uh = (struct udphdr *)((caddr_t)ip + iphlen); /* * Make mbuf data length reflect UDP length. * If not enough data to reflect UDP length, drop. */ len = ntohs((uint16_t)uh->uh_ulen); if (ip->ip_len != len) { if (len > ip->ip_len) { goto bad; } m_adj(m, len - ip->ip_len); ip->ip_len = len; } /* * Save a copy of the IP header in case we want restore it * for sending an ICMP error message in response. */ save_ip = *ip; save_ip.ip_len+= iphlen; /* tcp_input subtracts this */ /* * Checksum extended UDP header and data. */ if (uh->uh_sum) { memset(&((struct ipovly *)ip)->ih_mbuf, 0, sizeof(struct mbuf_ptr)); ((struct ipovly *)ip)->ih_x1 = 0; ((struct ipovly *)ip)->ih_len = uh->uh_ulen; if(cksum(m, len + sizeof(struct ip))) { goto bad; } } /* * handle DHCP/BOOTP */ if (ntohs(uh->uh_dport) == BOOTP_SERVER && (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr || ip->ip_dst.s_addr == 0xffffffff)) { bootp_input(m); goto bad; } /* * handle TFTP */ if (ntohs(uh->uh_dport) == TFTP_SERVER && ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) { tftp_input(m); goto bad; } if (slirp->restricted) { goto bad; } /* * Locate pcb for datagram. */ so = slirp->udp_last_so; if (so->so_lport != uh->uh_sport || so->so_laddr.s_addr != ip->ip_src.s_addr) { struct socket *tmp; for (tmp = slirp->udb.so_next; tmp != &slirp->udb; tmp = tmp->so_next) { if (tmp->so_lport == uh->uh_sport && tmp->so_laddr.s_addr == ip->ip_src.s_addr) { so = tmp; break; } } if (tmp == &slirp->udb) { so = NULL; } else { slirp->udp_last_so = so; } } if (so == NULL) { /* * If there's no socket for this packet, * create one */ so = socreate(slirp); if (!so) { goto bad; } if(udp_attach(so) == -1) { DEBUG_MISC((dfd," udp_attach errno = %d-%s\n", errno,strerror(errno))); sofree(so); goto bad; } /* * Setup fields */ so->so_laddr = ip->ip_src; so->so_lport = uh->uh_sport; if ((so->so_iptos = udp_tos(so)) == 0) so->so_iptos = ip->ip_tos; /* * XXXXX Here, check if it's in udpexec_list, * and if it is, do the fork_exec() etc. */ } so->so_faddr = ip->ip_dst; /* XXX */ so->so_fport = uh->uh_dport; /* XXX */ iphlen += sizeof(struct udphdr); m->m_len -= iphlen; m->m_data += iphlen; /* * Now we sendto() the packet. */ if(sosendto(so,m) == -1) { m->m_len += iphlen; m->m_data -= iphlen; *ip=save_ip; DEBUG_MISC((dfd,"udp tx errno = %d-%s\n",errno,strerror(errno))); icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno)); } m_free(so->so_m); /* used for ICMP if error on sorecvfrom */ /* restore the orig mbuf packet */ m->m_len += iphlen; m->m_data -= iphlen; *ip=save_ip; so->so_m=m; /* ICMP backup */ return; bad: m_free(m); }