ref: e4373dd1038fd8e0369d595283b032d011f28e59
parent: aeb857e367df5f414707fe054edc487386adbe54
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Thu Nov 7 16:24:27 EST 2024
ip/pppoe: properly zero-pad ethernet frames, optimize framing, limit mtu 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.
--- a/sys/src/cmd/ip/pppoe.c
+++ b/sys/src/cmd/ip/pppoe.c
@@ -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 @@
int cookielen;
uchar etherdst[6];
uchar ethersrc[6];
-int mtu = 1492;
+int mtu = Maxmtu;
int pktcompress, hdrcompress;
char *baud;
@@ -97,6 +161,8 @@
break;
case 'm':
mtu = atoi(EARGF(usage()));
+ if(mtu > Maxmtu)
+ mtu = Maxmtu;
break;
case 'i':
ipnet4 = EARGF(usage());
@@ -150,23 +216,6 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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");
--
⑨