/* * X.25 Packet Layer release 002 * * This is ALPHA test software. This code may break your machine, randomly fail to work with new * releases, misbehave and/or generally screw up. It might even work. * * This code REQUIRES 2.1.15 or higher * * This module: * This module is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * History * X.25 001 Split from x25_subr.c * mar/20/00 Daniela Squassoni Disabling/enabling of facilities * negotiation. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Parse a set of facilities into the facilities structure. Unrecognised * facilities are written to the debug log file. */ int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, unsigned long *vc_fac_mask) { unsigned int len; unsigned char *p = skb->data; len = *p++; *vc_fac_mask = 0; while (len > 0) { switch (*p & X25_FAC_CLASS_MASK) { case X25_FAC_CLASS_A: switch (*p) { case X25_FAC_REVERSE: facilities->reverse = (p[1] & 0x01); *vc_fac_mask |= X25_MASK_REVERSE; break; case X25_FAC_THROUGHPUT: facilities->throughput = p[1]; *vc_fac_mask |= X25_MASK_THROUGHPUT; break; default: printk(KERN_DEBUG "X.25: unknown facility %02X, value %02X\n", p[0], p[1]); break; } p += 2; len -= 2; break; case X25_FAC_CLASS_B: switch (*p) { case X25_FAC_PACKET_SIZE: facilities->pacsize_in = p[1]; facilities->pacsize_out = p[2]; *vc_fac_mask |= X25_MASK_PACKET_SIZE; break; case X25_FAC_WINDOW_SIZE: facilities->winsize_in = p[1]; facilities->winsize_out = p[2]; *vc_fac_mask |= X25_MASK_WINDOW_SIZE; break; default: printk(KERN_DEBUG "X.25: unknown facility %02X, values %02X, %02X\n", p[0], p[1], p[2]); break; } p += 3; len -= 3; break; case X25_FAC_CLASS_C: printk(KERN_DEBUG "X.25: unknown facility %02X, values %02X, %02X, %02X\n", p[0], p[1], p[2], p[3]); p += 4; len -= 4; break; case X25_FAC_CLASS_D: printk(KERN_DEBUG "X.25: unknown facility %02X, length %d, values %02X, %02X, %02X, %02X\n", p[0], p[1], p[2], p[3], p[4], p[5]); p += p[1] + 2; len -= p[1] + 2; break; } } return p - skb->data; } /* * Create a set of facilities. */ int x25_create_facilities(unsigned char *buffer, struct x25_facilities *facilities, unsigned long facil_mask) { unsigned char *p = buffer + 1; int len; if (facil_mask == 0) { buffer [0] = 0; /* length of the facilities field in call_req or call_accept packets */ len = 1; /* 1 byte for the length field */ return len; } if ((facilities->reverse != 0) && (facil_mask & X25_MASK_REVERSE)) { *p++ = X25_FAC_REVERSE; *p++ = (facilities->reverse) ? 0x01 : 0x00; } if ((facilities->throughput != 0) && (facil_mask & X25_MASK_THROUGHPUT)) { *p++ = X25_FAC_THROUGHPUT; *p++ = facilities->throughput; } if ((facilities->pacsize_in != 0 || facilities->pacsize_out != 0) && (facil_mask & X25_MASK_PACKET_SIZE)) { *p++ = X25_FAC_PACKET_SIZE; *p++ = (facilities->pacsize_in == 0) ? facilities->pacsize_out : facilities->pacsize_in; *p++ = (facilities->pacsize_out == 0) ? facilities->pacsize_in : facilities->pacsize_out; } if ((facilities->winsize_in != 0 || facilities->winsize_out != 0) && (facil_mask & X25_MASK_WINDOW_SIZE)) { *p++ = X25_FAC_WINDOW_SIZE; *p++ = (facilities->winsize_in == 0) ? facilities->winsize_out : facilities->winsize_in; *p++ = (facilities->winsize_out == 0) ? facilities->winsize_in : facilities->winsize_out; } len = p - buffer; buffer[0] = len - 1; return len; } /* * Try to reach a compromise on a set of facilities. * * The only real problem is with reverse charging. */ int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, struct x25_facilities *new) { struct x25_facilities *ours; struct x25_facilities theirs; int len; memset(&theirs, 0x00, sizeof(struct x25_facilities)); ours = &sk->protinfo.x25->facilities; *new = *ours; len = x25_parse_facilities(skb, &theirs, &sk->protinfo.x25->vc_facil_mask); /* * They want reverse charging, we won't accept it. */ if (theirs.reverse != 0 && ours->reverse == 0) { SOCK_DEBUG(sk, "X.25: rejecting reverse charging request"); return -1; } new->reverse = theirs.reverse; if (theirs.throughput != 0) { if (theirs.throughput < ours->throughput) { SOCK_DEBUG(sk, "X.25: throughput negotiated down"); new->throughput = theirs.throughput; } } if (theirs.pacsize_in != 0 && theirs.pacsize_out != 0) { if (theirs.pacsize_in < ours->pacsize_in) { SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down"); new->pacsize_in = theirs.pacsize_in; } if (theirs.pacsize_out < ours->pacsize_out) { SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down"); new->pacsize_out = theirs.pacsize_out; } } if (theirs.winsize_in != 0 && theirs.winsize_out != 0) { if (theirs.winsize_in < ours->winsize_in) { SOCK_DEBUG(sk, "X.25: window size inwards negotiated down"); new->winsize_in = theirs.winsize_in; } if (theirs.winsize_out < ours->winsize_out) { SOCK_DEBUG(sk, "X.25: window size outwards negotiated down"); new->winsize_out = theirs.winsize_out; } } return len; } /* * Limit values of certain facilities according to the capability of the * currently attached x25 link. */ void x25_limit_facilities(struct x25_facilities *facilities, struct x25_neigh *neighbour) { if( ! neighbour->extended ){ if( facilities->winsize_in > 7 ){ printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n"); facilities->winsize_in = 7; } if( facilities->winsize_out > 7 ){ facilities->winsize_out = 7; printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n"); } } }
