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An attempt to fix UDP ASSOCIATE mode

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This commit is contained in:
VasiliPupkin256 2020-08-03 23:48:54 +03:00
parent 3b5fa46e27
commit 6faae6d0c1
1 changed files with 28 additions and 11 deletions
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39
src/socks.c
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@ -348,23 +348,34 @@ fflush(stderr);
break;
}
if (fds[1].revents) {
// if we cant relay packet forward (can't resolve address or whatever)
// there is no way to report this individual error to the client
// so we silently drop it instead of closing the ASSOCIATION
sasize = sizeof(sin);
if((len = so._recvfrom(param->clisock, (char *)buf, 65535, 0, (struct sockaddr *)&sin, &sasize)) <= 10) {
if((len = so._recvfrom(param->clisock, (char *)buf, 65535, 0, (struct sockaddr *)&sin, &sasize)) < 0) {
param->res = 464;
break;
}
if(SAADDRLEN(&sin) != SAADDRLEN(&param->sincr) || memcmp(SAADDR(&sin), SAADDR(&param->sincr), SAADDRLEN(&sin))){
param->res = 465;
break;
// dropping packet recieved from an address that not belong to client
continue;
}
// we remember the client port on each relay
// it is not perfect, some packets may come from a previously connected client
// or being a miliciously formed by a hacker
// ideally we should build an association table between local and remote addresses
// but well...
*SAPORT(&param->sincr) = *SAPORT(&sin);
if(buf[0] || buf[1] || buf[2]) {
param->res = 466;
break;
}
size = 4;
if(len <= 10) continue;
switch(buf[3]) {
case 4:
size = 16;
if(len <= 10 + 16 - 4) continue;
case 1:
i = 4+size;
memcpy(SAADDR(&param->sinsr), buf+4, size);
@ -372,11 +383,12 @@ fflush(stderr);
break;
case 3:
size = buf[4];
if(len <= 10 + size - 4) continue;
for (i=4; size; i++, size--){
buf[i] = buf[i+1];
}
buf[i++] = 0;
if(!getip46(param->srv->family, buf+4, (struct sockaddr *) &param->sinsr)) RETURN(100);
if(!getip46(param->srv->family, buf+4, (struct sockaddr *) &param->sinsr)) continue;
break;
default:
RETURN(997);
@ -388,8 +400,7 @@ fflush(stderr);
sasize = sizeof(param->sinsr);
if(len > (int)i){
if(socksendto(param->remsock, (struct sockaddr *)&param->sinsr, buf+i, len - i, conf.timeouts[SINGLEBYTE_L]*1000) <= 0){
param->res = 467;
break;
continue;
}
param->statscli64+=(len - i);
param->nwrites++;
@ -413,7 +424,7 @@ fflush(stderr);
sasize = sizeof(param->sinsr);
buf[0]=buf[1]=buf[2]=0;
buf[3]=(*SAFAMILY(&param->sinsl) == AF_INET)?1:4;
if((len = so._recvfrom(param->remsock, (char *)buf+6+SAADDRLEN(&param->sinsl), 65535 - 10, 0, (struct sockaddr *)&param->sinsr, &sasize)) <= 0) {
if((len = so._recvfrom(param->remsock, (char *)buf+6+SAADDRLEN(&param->sinsl), 65535 - 10, 0, (struct sockaddr *)&param->sinsr, &sasize)) < 0) {
param->res = 468;
break;
}
@ -421,10 +432,16 @@ fflush(stderr);
param->nreads++;
memcpy(buf+4, SAADDR(&param->sinsr), SAADDRLEN(&param->sinsr));
memcpy(buf+4+SAADDRLEN(&param->sinsr), SAPORT(&param->sinsr), 2);
sasize = sizeof(sin);
if(socksendto(param->clisock, (struct sockaddr *)&sin, buf, len + 6 + SAADDRLEN(&param->sinsr), conf.timeouts[SINGLEBYTE_L]*1000) <=0){
param->res = 469;
break;
if(*SAPORT(&param->sincr) == 0 || *(uint32_t*)SAADDR(&param->sincr) == 0){
// client hasn't connected yet so we don't know his address
// dropping incoming packet
continue;
}
sasize = sizeof(param->sincr);
if(socksendto(param->clisock, (struct sockaddr *)&param->sincr, buf, len + 6 + SAADDRLEN(&param->sinsr), conf.timeouts[SINGLEBYTE_L]*1000) <=0){
continue;
}
#if SOCKSTRACE > 1
fprintf(stderr, "UDP packet relayed to client from %hu size %d\n",