diff options
Diffstat (limited to 'net/x25/x25_facilities.c')
| -rw-r--r-- | net/x25/x25_facilities.c | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/net/x25/x25_facilities.c b/net/x25/x25_facilities.c new file mode 100644 index 000000000000..a21bdb95f9a8 --- /dev/null +++ b/net/x25/x25_facilities.c @@ -0,0 +1,231 @@ +/* + * 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 <linux/kernel.h> +#include <linux/string.h> +#include <linux/skbuff.h> +#include <net/sock.h> +#include <net/x25.h> + +/* + * 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 char *p = skb->data; + unsigned int 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]); + len -= p[1] + 2; + p += 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) { + /* + * Length of the facilities field in call_req or + * call_accept packets + */ + buffer[0] = 0; + len = 1; /* 1 byte for the length field */ + return len; + } + + if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { + *p++ = X25_FAC_REVERSE; + *p++ = !!facilities->reverse; + } + + if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { + *p++ = X25_FAC_THROUGHPUT; + *p++ = facilities->throughput; + } + + if ((facilities->pacsize_in || facilities->pacsize_out) && + (facil_mask & X25_MASK_PACKET_SIZE)) { + *p++ = X25_FAC_PACKET_SIZE; + *p++ = facilities->pacsize_in ? : facilities->pacsize_out; + *p++ = facilities->pacsize_out ? : facilities->pacsize_in; + } + + if ((facilities->winsize_in || facilities->winsize_out) && + (facil_mask & X25_MASK_WINDOW_SIZE)) { + *p++ = X25_FAC_WINDOW_SIZE; + *p++ = facilities->winsize_in ? : facilities->winsize_out; + *p++ = facilities->winsize_out ? : facilities->winsize_in; + } + + 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_sock *x25 = x25_sk(sk); + struct x25_facilities *ours = &x25->facilities; + struct x25_facilities theirs; + int len; + + memset(&theirs, 0, sizeof(theirs)); + memcpy(new, ours, sizeof(*new)); + + len = x25_parse_facilities(skb, &theirs, &x25->vc_facil_mask); + + /* + * They want reverse charging, we won't accept it. + */ + if (theirs.reverse && ours->reverse) { + SOCK_DEBUG(sk, "X.25: rejecting reverse charging request"); + return -1; + } + + new->reverse = theirs.reverse; + + if (theirs.throughput) { + if (theirs.throughput < ours->throughput) { + SOCK_DEBUG(sk, "X.25: throughput negotiated down"); + new->throughput = theirs.throughput; + } + } + + if (theirs.pacsize_in && theirs.pacsize_out) { + 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 && theirs.winsize_out) { + 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 *nb) +{ + + if (!nb->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"); + } + } +} |