/* $NetBSD: ip_proxy.c,v 1.18 1999/08/24 16:10:35 bouyer Exp $ */ /* * Copyright (C) 1997-1998 by Darren Reed. * * Redistribution and use in source and binary forms are permitted * provided that this notice is preserved and due credit is given * to the original author and the contributors. */ #if !defined(lint) #if defined(__NetBSD__) static const char rcsid[] = "$NetBSD: ip_proxy.c,v 1.18 1999/08/24 16:10:35 bouyer Exp $"; #else static const char rcsid[] = "@(#)Id: ip_proxy.c,v 2.0.2.11.2.15 1998/11/22 01:50:29 darrenr Exp "; #endif #endif #if defined(__FreeBSD__) && defined(KERNEL) && !defined(_KERNEL) # define _KERNEL #endif #include #include #include #include #include #include #include #include #if !defined(_KERNEL) && !defined(KERNEL) # include # include # include #endif #ifndef linux # include #endif #include #if defined(_KERNEL) # if !defined(linux) # include # else # include # endif #endif #if !defined(__SVR4) && !defined(__svr4__) # ifndef linux # include # endif #else # include # include # include # include #endif #if __FreeBSD__ > 2 # include #endif #include #ifdef sun # include #endif #include #include #include #include #ifndef linux # include #endif #include #include #include #include "netinet/ip_compat.h" #include #include "netinet/ip_fil.h" #include "netinet/ip_proxy.h" #include "netinet/ip_nat.h" #include "netinet/ip_state.h" #ifndef MIN #define MIN(a,b) (((a)<(b))?(a):(b)) #endif static ap_session_t *ap_new_session __P((aproxy_t *, ip_t *, fr_info_t *, nat_t *)); int ap_fixseqack __P((fr_info_t *, ip_t *, ap_session_t *, int inc)); #define AP_SESS_SIZE 53 #if defined(_KERNEL) && !defined(linux) #include "netinet/ip_ftp_pxy.c" #endif ap_session_t *ap_sess_tab[AP_SESS_SIZE]; ap_session_t *ap_sess_list = NULL; aproxy_t ap_proxies[] = { #ifdef IPF_FTP_PROXY { "ftp", (char)IPPROTO_TCP, 0, 0, ippr_ftp_init, ippr_ftp_in, ippr_ftp_out }, #endif { "", '\0', 0, 0, NULL, NULL } }; int ap_ok(ip, tcp, nat) ip_t *ip; tcphdr_t *tcp; ipnat_t *nat; { aproxy_t *apr = nat->in_apr; u_short dport = nat->in_dport; if (!apr || (apr && (apr->apr_flags & APR_DELETE)) || (ip->ip_p != apr->apr_p)) return 0; if ((tcp && (tcp->th_dport != dport)) || (!tcp && dport)) return 0; return 1; } /* * Allocate a new application proxy structure and fill it in with the * relevant details. call the init function once complete, prior to * returning. */ static ap_session_t *ap_new_session(apr, ip, fin, nat) aproxy_t *apr; ip_t *ip; fr_info_t *fin; nat_t *nat; { register ap_session_t *aps; tcphdr_t *tcp; u_short dport; u_int hv; if (!apr || (apr && (apr->apr_flags & APR_DELETE)) || (ip->ip_p != apr->apr_p)) return NULL; if (!(fin->fin_fi.fi_fl & FI_TCPUDP)) tcp = NULL; else tcp = (tcphdr_t *)fin->fin_dp; dport = nat->nat_ptr->in_dport; if ((tcp && (tcp->th_dport != dport)) || (!tcp && dport)) return NULL; hv = ip->ip_src.s_addr ^ ip->ip_dst.s_addr; hv *= 651733; if (tcp) { hv ^= (tcp->th_sport + tcp->th_dport); hv *= 5; } hv %= AP_SESS_SIZE; KMALLOC(aps, ap_session_t *, sizeof(*aps)); if (!aps) return NULL; bzero((char *)aps, sizeof(*aps)); aps->aps_apr = apr; aps->aps_src = ip->ip_src; aps->aps_dst = ip->ip_dst; aps->aps_p = ip->ip_p; if (tcp) { aps->aps_sport = tcp->th_sport; aps->aps_dport = tcp->th_dport; } aps->aps_data = NULL; aps->aps_psiz = 0; aps->aps_hnext = ap_sess_tab[hv]; aps->aps_next = ap_sess_list; ap_sess_list = aps; aps->aps_nat = nat; aps->aps_hv = hv; nat->nat_aps = aps; ap_sess_tab[hv] = aps; (void) (*apr->apr_init)(fin, ip, aps, nat); return aps; } /* * check to see if a packet should be passed through an active proxy routine * if one has been setup for it. */ int ap_check(ip, fin, nat) ip_t *ip; fr_info_t *fin; nat_t *nat; { ap_session_t *aps; aproxy_t *apr; tcphdr_t *tcp = NULL; u_32_t sum; int err; if ((aps = nat->nat_aps) == NULL) aps = ap_new_session(nat->nat_ptr->in_apr, ip, fin, nat); if ((aps != NULL) && (aps->aps_p == ip->ip_p)) { if (ip->ip_p == IPPROTO_TCP) { tcp = (tcphdr_t *)fin->fin_dp; /* * verify that the checksum is correct. If not, then * don't do anything with this packet. */ #if SOLARIS && defined(_KERNEL) sum = fr_tcpsum(fin->fin_qfm, ip, tcp, ip->ip_len); #else sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp, ip->ip_len); #endif if (sum != 0) { frstats[fin->fin_out].fr_tcpbad++; return -1; } } apr = aps->aps_apr; err = 0; if (fin->fin_out) { if (apr->apr_outpkt) err = (*apr->apr_outpkt)(fin, ip, aps, nat); } else { if (apr->apr_inpkt) err = (*apr->apr_inpkt)(fin, ip, aps, nat); } if (tcp != NULL) { err = ap_fixseqack(fin, ip, aps, err); tcp->th_sum = 0; #if SOLARIS && defined(_KERNEL) tcp->th_sum = fr_tcpsum(fin->fin_qfm, ip, tcp, ip->ip_len); #else tcp->th_sum = fr_tcpsum(*(mb_t **)fin->fin_mp, ip, tcp, ip->ip_len); #endif } aps->aps_bytes += ip->ip_len; aps->aps_pkts++; return 2; } return -1; } aproxy_t *ap_match(pr, name) u_char pr; char *name; { aproxy_t *ap; for (ap = ap_proxies; ap->apr_p; ap++) if ((ap->apr_p == pr) && !strncmp(name, ap->apr_label, sizeof(ap->apr_label))) { ap->apr_ref++; return ap; } return NULL; } void ap_free(ap) aproxy_t *ap; { ap->apr_ref--; } void aps_free(aps) ap_session_t *aps; { ap_session_t *a, **ap; u_int hv; if (!aps) return; hv = aps->aps_hv; for (ap = ap_sess_tab + hv; (a = *ap); ap = &a->aps_hnext) if (a == aps) { *ap = a->aps_hnext; break; } for (ap = &ap_sess_list; (a = *ap); ap = &a->aps_next) if (a == aps) { *ap = a->aps_next; break; } if (a) { if (aps->aps_data && aps->aps_psiz) KFREES(aps->aps_data, aps->aps_psiz); KFREE(aps); } } int ap_fixseqack(fin, ip, aps, inc) fr_info_t *fin; ip_t *ip; ap_session_t *aps; int inc; { int sel, ch = 0, out, nlen; u_32_t seq1, seq2; tcphdr_t *tcp; tcp = (tcphdr_t *)fin->fin_dp; out = fin->fin_out; nlen = ip->ip_len; nlen -= (ip->ip_hl << 2) + (tcp->th_off << 2); if (out != 0) { seq1 = (u_32_t)ntohl(tcp->th_seq); sel = aps->aps_sel[out]; /* switch to other set ? */ if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) && (seq1 > aps->aps_seqmin[!sel])) sel = aps->aps_sel[out] = !sel; if (aps->aps_seqoff[sel]) { seq2 = aps->aps_seqmin[sel] - aps->aps_seqoff[sel]; if (seq1 > seq2) { seq2 = aps->aps_seqoff[sel]; seq1 += seq2; tcp->th_seq = htonl(seq1); ch = 1; } } if (inc && (seq1 > aps->aps_seqmin[!sel])) { aps->aps_seqmin[!sel] = seq1 + nlen - 1; aps->aps_seqoff[!sel] = aps->aps_seqoff[sel] + inc; } /***/ seq1 = ntohl(tcp->th_ack); sel = aps->aps_sel[1 - out]; /* switch to other set ? */ if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) && (seq1 > aps->aps_ackmin[!sel])) sel = aps->aps_sel[1 - out] = !sel; if (aps->aps_ackoff[sel] && (seq1 > aps->aps_ackmin[sel])) { seq2 = aps->aps_ackoff[sel]; tcp->th_ack = htonl(seq1 - seq2); ch = 1; } } else { seq1 = ntohl(tcp->th_seq); sel = aps->aps_sel[out]; /* switch to other set ? */ if ((aps->aps_ackmin[!sel] > aps->aps_ackmin[sel]) && (seq1 > aps->aps_ackmin[!sel])) sel = aps->aps_sel[out] = !sel; if (aps->aps_ackoff[sel]) { seq2 = aps->aps_ackmin[sel] - aps->aps_ackoff[sel]; if (seq1 > seq2) { seq2 = aps->aps_ackoff[sel]; seq1 += seq2; tcp->th_seq = htonl(seq1); ch = 1; } } if (inc && (seq1 > aps->aps_ackmin[!sel])) { aps->aps_ackmin[!sel] = seq1 + nlen - 1; aps->aps_ackoff[!sel] = aps->aps_ackoff[sel] + inc; } /***/ seq1 = ntohl(tcp->th_ack); sel = aps->aps_sel[1 - out]; /* switch to other set ? */ if ((aps->aps_seqmin[!sel] > aps->aps_seqmin[sel]) && (seq1 > aps->aps_seqmin[!sel])) sel = aps->aps_sel[1 - out] = !sel; if (aps->aps_seqoff[sel] && (seq1 > aps->aps_seqmin[sel])) { seq2 = aps->aps_seqoff[sel]; tcp->th_ack = htonl(seq1 - seq2); ch = 1; } } return ch ? 2 : 0; }