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ip/pppoe: properly zero-pad ethernet frames, optimize framing, limit mtu

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we should properly zero-pad the ethernet frames we send out
instead of sending random garbage.

for ppp -> ethernet, the ethernet header is fixed, so we
can generate it once before the read()/write() loop.

Use a 1514 byte buffer for all ethernet frames as the
maximum, and limit the mtu to 1514-14-8 -> 1492.
This commit is contained in:
cinap_lenrek 2024-11-07 21:24:27 +00:00
parent aeb857e367
commit e4373dd103
1 changed files with 84 additions and 84 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

168
sys/src/cmd/ip/pppoe.c
View file

@ -7,6 +7,70 @@
#include <libc.h>
#include <ip.h>
typedef struct Etherhdr Etherhdr;
struct Etherhdr {
uchar dst[6];
uchar src[6];
uchar type[2];
};
enum {
EtherHdrSz = 6+6+2,
EtherMintu = 60,
EtherMaxtu = 1500+EtherHdrSz,
EtherPppoeDiscovery = 0x8863,
EtherPppoeSession = 0x8864,
};
uchar etherbcast[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
typedef struct Pppoehdr Pppoehdr;
struct Pppoehdr {
uchar verstype;
uchar code;
uchar sessid[2];
uchar length[2]; /* of payload */
};
enum {
PppoeHdrSz = 1+1+2+2,
Hdr = EtherHdrSz+PppoeHdrSz,
Maxmtu = EtherMaxtu - (Hdr+2), /* 2 bytes for PPP header */
};
enum {
VersType = 0x11,
/* Discovery codes */
CodeDiscInit = 0x09, /* discovery init */
CodeDiscOffer = 0x07, /* discovery offer */
CodeDiscReq = 0x19, /* discovery request */
CodeDiscSess = 0x65, /* session confirmation */
CodeDiscTerm = 0xa7,
/* Session codes */
CodeSession = 0x00,
};
typedef struct Taghdr Taghdr;
struct Taghdr {
uchar type[2];
uchar length[2]; /* of value */
};
enum {
TagEnd = 0x0000, /* end of tag list */
TagSrvName = 0x0101, /* service name */
TagAcName = 0x0102, /* access concentrator name */
TagHostUniq = 0x0103, /* nonce */
TagAcCookie = 0x0104, /* a.c. cookie */
TagVendSpec = 0x0105, /* vendor specific */
TagRelaySessId = 0x0110, /* relay session id */
TagSrvNameErr = 0x0201, /* service name error (ascii) */
TagAcSysErr = 0x0202, /* a.c. system error */
};
void dumppkt(uchar*);
uchar *findtag(uchar*, int, int*, int);
void hexdump(uchar*, int);
@ -32,7 +96,7 @@ uchar *cookie;
int cookielen;
uchar etherdst[6];
uchar ethersrc[6];
int mtu = 1492;
int mtu = Maxmtu;
int pktcompress, hdrcompress;
char *baud;
@ -97,6 +161,8 @@ main(int argc, char **argv)
break;
case 'm':
mtu = atoi(EARGF(usage()));
if(mtu > Maxmtu)
mtu = Maxmtu;
break;
case 'i':
ipnet4 = EARGF(usage());
@ -150,23 +216,6 @@ main(int argc, char **argv)
execppp(pppoe(dev));
}
typedef struct Etherhdr Etherhdr;
struct Etherhdr {
uchar dst[6];
uchar src[6];
uchar type[2];
};
enum {
EtherHdrSz = 6+6+2,
EtherMintu = 60,
EtherPppoeDiscovery = 0x8863,
EtherPppoeSession = 0x8864,
};
uchar etherbcast[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
int
etherhdr(uchar *pkt, uchar *dst, int type)
{
@ -178,33 +227,6 @@ etherhdr(uchar *pkt, uchar *dst, int type)
return EtherHdrSz;
}
typedef struct Pppoehdr Pppoehdr;
struct Pppoehdr {
uchar verstype;
uchar code;
uchar sessid[2];
uchar length[2]; /* of payload */
};
enum {
PppoeHdrSz = 1+1+2+2,
Hdr = EtherHdrSz+PppoeHdrSz,
};
enum {
VersType = 0x11,
/* Discovery codes */
CodeDiscInit = 0x09, /* discovery init */
CodeDiscOffer = 0x07, /* discovery offer */
CodeDiscReq = 0x19, /* discovery request */
CodeDiscSess = 0x65, /* session confirmation */
CodeDiscTerm = 0xa7,
/* Session codes */
CodeSession = 0x00,
};
int
pppoehdr(uchar *pkt, int code, int sessid)
{
@ -217,24 +239,6 @@ pppoehdr(uchar *pkt, int code, int sessid)
return PppoeHdrSz;
}
typedef struct Taghdr Taghdr;
struct Taghdr {
uchar type[2];
uchar length[2]; /* of value */
};
enum {
TagEnd = 0x0000, /* end of tag list */
TagSrvName = 0x0101, /* service name */
TagAcName = 0x0102, /* access concentrator name */
TagHostUniq = 0x0103, /* nonce */
TagAcCookie = 0x0104, /* a.c. cookie */
TagVendSpec = 0x0105, /* vendor specific */
TagRelaySessId = 0x0110, /* relay session id */
TagSrvNameErr = 0x0201, /* service name error (ascii) */
TagAcSysErr = 0x0202, /* a.c. system error */
};
int
tag(uchar *pkt, int type, void *value, int nvalue)
{
@ -473,11 +477,9 @@ int
pppoe(char *ether)
{
char buf[128];
uchar pkt[1520];
uchar pkt[EtherMaxtu];
int dfd, sfd, p[2], n, sz, timeout;
Pppoehdr *ph;
ph = (Pppoehdr*)(pkt+EtherHdrSz);
snprint(buf, sizeof buf, "%s!%d", ether, EtherPppoeDiscovery);
if((dfd = dial(buf, nil, nil, nil)) < 0)
fatal("dial %s: %r\n", buf);
@ -549,16 +551,17 @@ Restart:
break;
case 0:
close(dfd);
while((n = read(sfd, pkt, sizeof pkt)) > 0){
if(malformed(pkt, n, EtherPppoeSession)
|| ph->code != 0x00 || nhgets(ph->sessid) != sessid){
if(debug)
fprint(2, "malformed session pkt: %r\n");
if(debug)
dumppkt(pkt);
pppoehdr((uchar*)buf, 0x00, sessid);
while((sz = read(sfd, pkt, sizeof pkt)) > 0){
if(sz < Hdr
|| pkt[EtherHdrSz+1] != 0x00 /* code */
|| pkt[EtherHdrSz+2] != (uchar)buf[2] /* sessid[0] */
|| pkt[EtherHdrSz+3] != (uchar)buf[3] /* sessid[1] */
|| (n = nhgets(pkt+Hdr-2)) > sz-Hdr)
continue;
}
if(write(p[0], pkt+Hdr, nhgets(ph->length)) < 0){
if(write(p[0], pkt+Hdr, n) < 0){
if(debug)
fprint(2, "write to ppp failed: %r\n");
break;
@ -574,17 +577,14 @@ Restart:
break;
case 0:
close(dfd);
etherhdr(pkt, etherdst, EtherPppoeSession);
pppoehdr(pkt+EtherHdrSz, 0x00, sessid);
while((n = read(p[0], pkt+Hdr, sizeof pkt-Hdr)) > 0){
etherhdr(pkt, etherdst, EtherPppoeSession);
pppoehdr(pkt+EtherHdrSz, 0x00, sessid);
hnputs(pkt+Hdr-2, n);
sz = Hdr+n;
if(debug > 1){
dumppkt(pkt);
hexdump(pkt, sz);
}
if(sz < EtherMintu)
sz = EtherMintu;
for(sz = Hdr+n; sz < EtherMintu; sz++)
pkt[sz] = 0;
if(write(sfd, pkt, sz) < 0){
if(debug)
fprint(2, "write to ether failed: %r");