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pppoe-server: -n to use vendor specific tag as remote*N*umber. #38

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pppoe-server: -n to use vendor specific tag as remote*N*umber. #38

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71 changes: 65 additions & 6 deletions src/pppoe-server.c
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,8 @@ int NumInterfaces = 0;
int MaxInterfaces = 0;
int draining = 0;

int vendorTagAsRemoteNumber = 0; /* 0 is disabled, 1 use "Agent Circuit ID", 2 use "Agent Remote ID". */

/* The number of session slots */
size_t NumSessionSlots;

Expand Down Expand Up @@ -176,6 +178,7 @@ static PPPoETag hostUniq;
static PPPoETag relayId;
static PPPoETag receivedCookie;
static PPPoETag requestedService;
static PPPoETag vendorTag;

#define HOSTNAMELEN 256

Expand Down Expand Up @@ -514,6 +517,14 @@ parsePADRTags(uint16_t type, uint16_t len, unsigned char *data,
requestedService.length = htons(len);
memcpy(requestedService.payload, data, len);
break;
case TAG_VENDOR_SPECIFIC:
/* We only care about vendor 0x00000DE9 ("BBF" aka Broadband Forum, IANA) */
if (len >= 4 && *(uint32_t*)data == htonl(0xDE9)) {
vendorTag.type = htons(type);
vendorTag.length = htons(len);
memcpy(vendorTag.payload, data, len);
}
break;
}
}

Expand Down Expand Up @@ -881,6 +892,7 @@ processPADR(Interface *ethif, PPPoEPacket *packet, int len)
hostUniq.type = 0;
receivedCookie.type = 0;
requestedService.type = 0;
vendorTag.type = 0;

/* Ignore PADR's not directed at us */
if (memcmp(packet->ethHdr.h_dest, myAddr, ETH_ALEN)) return;
Expand Down Expand Up @@ -979,6 +991,7 @@ processPADR(Interface *ethif, PPPoEPacket *packet, int len)
cliSession->funcs = &DefaultSessionFunctionTable;
cliSession->startTime = time(NULL);
cliSession->serviceName = serviceName;
cliSession->remoteNumber = NULL;

/* Create child process, send PADS packet back */
child = fork();
Expand Down Expand Up @@ -1071,6 +1084,32 @@ processPADR(Interface *ethif, PPPoEPacket *packet, int len)
cursor += ntohs(hostUniq.length) + TAG_HDR_SIZE;
plen += ntohs(hostUniq.length) + TAG_HDR_SIZE;
}
if (vendorTag.type && vendorTag.length && vendorTagAsRemoteNumber) {
/* we know the Vendor-ID (32 bits) is 0xDE9, we can skip that */
int len = ntohs(vendorTag.length) - 4;
char* parse = (char*)vendorTag.payload + 4;

while (len >= 2) {
uint8_t tag = parse[0];
uint8_t tlen = parse[1];

parse += 2;
len -= 2;

/* corrupted packet, or malicious manipulation */
if (tlen > len)
break;

if (tag == vendorTagAsRemoteNumber) {
/* correct variant */
cliSession->remoteNumber = strndup(parse, tlen);
break;
}

len -= tlen;
parse += tlen;
}
}
pads.length = htons(plen);
sendPacket(NULL, sock, &pads, (int) (plen + HDR_SIZE));

Expand Down Expand Up @@ -1209,7 +1248,7 @@ main(int argc, char **argv)
char const *s;
int cookie_ok = 0;

char const *options = "X:ix:hI:C:L:R:T:m:FN:f:O:o:skp:lrudPS:q:Q:H:M:U:g:";
char const *options = "X:ix:hI:C:L:R:T:m:FN:f:O:o:skp:lrudPS:q:Q:H:M:U:g:n:";

if (getuid() != geteuid() ||
getgid() != getegid()) {
Expand Down Expand Up @@ -1457,6 +1496,18 @@ main(int argc, char **argv)
SET_STRING(unix_control, optarg);
break;

case 'n':
if (sscanf(optarg, "%d", &opt) != 1) {
usage(argv[0]);
exit(EXIT_FAILURE);
}
if (opt < 0 || opt > 2) {
fprintf(stderr, "-n: Value must be in the range 0 to 2\n");
exit(EXIT_FAILURE);
}
vendorTagAsRemoteNumber = opt;
break;

case 'h':
usage(argv[0]);
exit(EXIT_SUCCESS);
Expand Down Expand Up @@ -1989,11 +2040,17 @@ startPPPD(ClientSession *session)
argv[c++] = "default-asyncmap";

argv[c++] = "remotenumber";
snprintf(buffer, SMALLBUF, "%02x:%02x:%02x:%02x:%02x:%02x",
session->eth[0], session->eth[1], session->eth[2],
session->eth[3], session->eth[4], session->eth[5]);
if (!(argv[c++] = strdup(buffer))) {
exit(EXIT_FAILURE);
if (session->remoteNumber) {
if (!(argv[c++] = strdup(session->remoteNumber))) {
exit(EXIT_FAILURE);
}
} else {
snprintf(buffer, SMALLBUF, "%02x:%02x:%02x:%02x:%02x:%02x",
session->eth[0], session->eth[1], session->eth[2],
session->eth[3], session->eth[4], session->eth[5]);
if (!(argv[c++] = strdup(buffer))) {
exit(EXIT_FAILURE);
}
}

if (PassUnitOptionToPPPD) {
Expand Down Expand Up @@ -2178,6 +2235,8 @@ pppoe_free_session(ClientSession *ses)
ses->pid = 0;
memset(ses->eth, 0, ETH_ALEN);
ses->flags = 0;
free(ses->remoteNumber);
ses->remoteNumber = NULL;
NumActiveSessions--;
return 0;
}
Expand Down
1 change: 1 addition & 0 deletions src/pppoe-server.h
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,7 @@ typedef struct ClientSessionStruct {
time_t startTime; /* When session started */
char const *serviceName; /* Service name */
uint16_t requested_mtu; /* Requested PPP_MAX_PAYLOAD per RFC 4638 */
char *remoteNumber; /* Vendor-Specific tag extracted remote number ... this is a bit of a hack */
} ClientSession;

/* Hack for daemonizing */
Expand Down