/* * Copyright (c) 1982, 1986, 1988, 1990, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)udp_usrreq.c 8.4 (Berkeley) 1/21/94 * udp_usrreq.c,v 1.4 1994/10/02 17:48:45 phk Exp */ /* * Changes and additions relating to SLiRP * Copyright (c) 1995 Danny Gasparovski. * * Please read the file COPYRIGHT for the * terms and conditions of the copyright. */ #include #include "ip_icmp.h" #define SLIRP_COMPILATION 1 #include "sockets.h" #ifdef LOG_ENABLED struct udpstat udpstat; #endif /* Keeps track of the number of DNS requests. Used to implement the firewall * option that restricts the number of DNS requests (-max_dns_conns). */ u_int dns_num_conns; struct socket udb; static u_int8_t udp_tos(struct socket *so); static void udp_emu(struct socket *so, struct mbuf *m); /* * UDP protocol implementation. * Per RFC 768, August, 1980. */ #ifndef COMPAT_42 #define UDPCKSUM 1 #else #define UDPCKSUM 0 /* XXX */ #endif struct socket *udp_last_so = &udb; void udp_init(void) { udb.so_next = udb.so_prev = &udb; dns_num_conns = 0; } /* m->m_data points at ip packet header * m->m_len length ip packet * ip->ip_len length data (IPDU) */ void udp_input(register struct mbuf *m, int iphlen) { register struct ip *ip; register struct udphdr *uh; /* struct mbuf *opts = 0;*/ int len; struct ip save_ip; struct socket *so; DEBUG_CALL("udp_input"); DEBUG_ARG("m = %lx", (long)m); DEBUG_ARG("iphlen = %d", iphlen); STAT(udpstat.udps_ipackets++); /* * 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((u_int16_t)uh->uh_ulen); if (ip->ip_len != len) { if (len > ip->ip_len) { STAT(udpstat.udps_badlen++); goto bad; } m_adj(m, len - ip->ip_len); ip->ip_len = len; } /* ------------------------------------------------------*/ /* User mode network stack restrictions */ /* slirp_should_drop requires host byte ordering in arguments */ time_t timestamp = time(NULL); if (slirp_should_drop(ntohl(ip->ip_dst.addr), ntohs(uh->uh_dport.port), IPPROTO_UDP)) { slirp_drop_log( "Dropped UDP: src: 0x%08lx:0x%04x dst: 0x%08lx:0x%04x %ld\n", ntohl(ip->ip_src.addr), ntohs(uh->uh_sport.port), ntohl(ip->ip_dst.addr), ntohs(uh->uh_dport.port), timestamp ); goto bad; /* drop the packet */ } else { slirp_drop_log( "Allowed UDP: src: 0x%08lx:0x%04x dst: 0x%08lx:0x%04x %ld\n", ntohl(ip->ip_src.addr), ntohs(uh->uh_sport.port), ntohl(ip->ip_dst.addr), ntohs(uh->uh_dport.port), timestamp ); } /* ------------------------------------------------------*/ /* * 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 (UDPCKSUM && 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; /* keep uh_sum for ICMP reply * uh->uh_sum = cksum(m, len + sizeof (struct ip)); * if (uh->uh_sum) { */ if(cksum(m, len + sizeof(struct ip))) { STAT(udpstat.udps_badsum++); goto bad; } } /* * handle DHCP/BOOTP */ if (port_geth(uh->uh_dport) == BOOTP_SERVER) { bootp_input(m); goto bad; } if (slirp_restrict) goto bad; /* * handle TFTP */ if (port_geth(uh->uh_dport) == TFTP_SERVER) { tftp_input(m); goto bad; } // DNS logging and FW rules if (ntohs(uh->uh_dport.port) == 53) { if (!slirp_dump_dns(m)) { DEBUG_MISC((dfd,"Error logging DNS packet")); } dns_num_conns++; if (slirp_get_max_dns_conns() != -1 && dns_num_conns > slirp_get_max_dns_conns()) goto bad; } /* * Locate pcb for datagram. */ so = udp_last_so; if (so->so_laddr_port != port_geth(uh->uh_sport) || so->so_laddr_ip != ip_geth(ip->ip_src)) { struct socket *tmp; for (tmp = udb.so_next; tmp != &udb; tmp = tmp->so_next) { if (tmp->so_laddr_port == port_geth(uh->uh_sport) && tmp->so_laddr_ip == ip_geth(ip->ip_src)) { tmp->so_faddr_ip = ip_geth(ip->ip_dst); tmp->so_faddr_port = port_geth(uh->uh_dport); so = tmp; break; } } if (tmp == &udb) { so = NULL; } else { STAT(udpstat.udpps_pcbcachemiss++); udp_last_so = so; } } if (so == NULL) { /* * If there's no socket for this packet, * create one */ if ((so = socreate()) == NULL) goto bad; if(udp_attach(so) == -1) { DEBUG_MISC((dfd," udp_attach errno = %d-%s\n", errno,errno_str)); sofree(so); goto bad; } /* * Setup fields */ /* udp_last_so = so; */ so->so_laddr_ip = ip_geth(ip->ip_src); so->so_laddr_port = port_geth(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_geth(ip->ip_dst); /* XXX */ so->so_faddr_port = port_geth(uh->uh_dport); /* XXX */ iphlen += sizeof(struct udphdr); m->m_len -= iphlen; m->m_data += iphlen; /* * Now we sendto() the packet. */ if (so->so_emu) udp_emu(so, m); 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, errno_str)); icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,errno_str); } 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_freem(m); /* if (opts) m_freem(opts); */ return; } int udp_output2_(struct socket *so, struct mbuf *m, const SockAddress* saddr, const SockAddress* daddr, int iptos) { register struct udpiphdr *ui; uint32_t saddr_ip = sock_address_get_ip(saddr); uint32_t daddr_ip = sock_address_get_ip(daddr); int saddr_port = sock_address_get_port(saddr); int daddr_port = sock_address_get_port(daddr); int error = 0; DEBUG_CALL("udp_output"); DEBUG_ARG("so = %lx", (long)so); DEBUG_ARG("m = %lx", (long)m); DEBUG_ARG("saddr = %lx", (long) saddr_ip); DEBUG_ARG("daddr = %lx", (long) daddr_ip); /* * Adjust for header */ m->m_data -= sizeof(struct udpiphdr); m->m_len += sizeof(struct udpiphdr); /* * Fill in mbuf with extended UDP header * and addresses and length put into network format. */ ui = mtod(m, struct udpiphdr *); memset(&ui->ui_i.ih_mbuf, 0 , sizeof(struct mbuf_ptr)); ui->ui_x1 = 0; ui->ui_pr = IPPROTO_UDP; ui->ui_len = htons(m->m_len - sizeof(struct ip)); /* + sizeof (struct udphdr)); */ /* XXXXX Check for from-one-location sockets, or from-any-location sockets */ ui->ui_src = ip_seth(saddr_ip); ui->ui_dst = ip_seth(daddr_ip); ui->ui_sport = port_seth(saddr_port); ui->ui_dport = port_seth(daddr_port); ui->ui_ulen = ui->ui_len; /* * Stuff checksum and output datagram. */ ui->ui_sum = 0; if (UDPCKSUM) { if ((ui->ui_sum = cksum(m, /* sizeof (struct udpiphdr) + */ m->m_len)) == 0) ui->ui_sum = 0xffff; } ((struct ip *)ui)->ip_len = m->m_len; ((struct ip *)ui)->ip_ttl = IPDEFTTL; ((struct ip *)ui)->ip_tos = iptos; STAT(udpstat.udps_opackets++); // DNS logging if (so != NULL && so->so_faddr_port == 53) { /*so has host byte order */ if (!slirp_dump_dns(m)) { DEBUG_MISC((dfd,"Error logging DNS packet")); } } error = ip_output(so, m); return (error); } int udp_output_(struct socket *so, struct mbuf *m, SockAddress* from) { SockAddress saddr, daddr; uint32_t saddr_ip; uint16_t saddr_port; saddr_ip = sock_address_get_ip(from); saddr_port = sock_address_get_port(from); if ((so->so_faddr_ip & 0xffffff00) == special_addr_ip) { saddr_ip = so->so_faddr_ip; if ((so->so_faddr_ip & 0x000000ff) == 0xff) saddr_ip = alias_addr_ip; } sock_address_init_inet( &saddr, saddr_ip, saddr_port ); sock_address_init_inet( &daddr, so->so_laddr_ip, so->so_laddr_port ); return udp_output2_(so, m, &saddr, &daddr, so->so_iptos); } int udp_attach(struct socket *so) { so->s = socket_anyaddr_server( 0, SOCKET_DGRAM ); if (so->s != -1) { /* success, insert in queue */ so->so_expire = curtime + SO_EXPIRE; insque(so,&udb); } return(so->s); } void udp_detach(struct socket *so) { socket_close(so->s); /* if (so->so_m) m_free(so->so_m); done by sofree */ sofree(so); } static const struct tos_t udptos[] = { {0, 53, IPTOS_LOWDELAY, 0}, /* DNS */ {517, 517, IPTOS_LOWDELAY, EMU_TALK}, /* talk */ {518, 518, IPTOS_LOWDELAY, EMU_NTALK}, /* ntalk */ {0, 7648, IPTOS_LOWDELAY, EMU_CUSEEME}, /* Cu-Seeme */ {0, 0, 0, 0} }; static u_int8_t udp_tos(struct socket *so) { int i = 0; while(udptos[i].tos) { if ((udptos[i].fport && so->so_faddr_port == udptos[i].fport) || (udptos[i].lport && so->so_laddr_port == udptos[i].lport)) { so->so_emu = udptos[i].emu; return udptos[i].tos; } i++; } return 0; } /* * Here, talk/ytalk/ntalk requests must be emulated */ static void udp_emu(struct socket *so, struct mbuf *m) { SockAddress sockaddr; struct cu_header { uint16_t d_family; // destination family uint16_t d_port; // destination port uint32_t d_addr; // destination address uint16_t s_family; // source family uint16_t s_port; // source port uint32_t so_addr; // source address uint32_t seqn; // sequence number uint16_t message; // message uint16_t data_type; // data type uint16_t pkt_len; // packet length } *cu_head; switch(so->so_emu) { case EMU_CUSEEME: /* * Cu-SeeMe emulation. * Hopefully the packet is more that 16 bytes long. We don't * do any other tests, just replace the address and port * fields. */ if (m->m_len >= sizeof (*cu_head)) { if (socket_get_address(so->s, &sockaddr) < 0) return; cu_head = mtod(m, struct cu_header *); cu_head->s_port = htons( sock_address_get_port(&sockaddr)); cu_head->so_addr = htonl( sock_address_get_ip(&sockaddr)); } return; } } struct socket * udp_listen(u_int port, u_int32_t laddr, u_int lport, int flags) { struct socket *so; SockAddress addr; uint32_t addr_ip; if ((so = socreate()) == NULL) { free(so); return NULL; } so->s = socket_anyaddr_server( port, SOCKET_DGRAM ); so->so_expire = curtime + SO_EXPIRE; so->so_haddr_port = port; insque(so,&udb); if (so->s < 0) { udp_detach(so); return NULL; } socket_get_address(so->s, &addr); so->so_faddr_port = sock_address_get_port(&addr); addr_ip = sock_address_get_ip(&addr); if (addr_ip == 0 || addr_ip == loopback_addr_ip) so->so_faddr_ip = alias_addr_ip; else so->so_faddr_ip = addr_ip; so->so_laddr_port = lport; so->so_laddr_ip = laddr; if (flags != SS_FACCEPTONCE) so->so_expire = 0; so->so_state = SS_ISFCONNECTED; return so; } int udp_unlisten (u_int port) { return slirp_unredir(1, port); }