int strategy_choose_remote_addr(vpn_ctx_t *ctx) {
// rules:
// 1. if there isn't any address received from within ADDR_TIMEOUT
// choose latest
// 2. if there are some addresses received from within ADDR_TIMEOUT
// choose randomly from them
//
// how we do this efficiently
// 1. scan once and find latest, total number of not timed out addresses
// 2. if number <= 1, use latest
// 3. if number > 1, generate random i in (0, number),
// scan again and pick (i)th address not timed out
int i, total_not_timed_out = 0, chosen;
time_t now;
addr_info_t *latest = NULL, *temp;
if (ctx->nknown_addr == 0) {
return 0;
}
time(&now);
for (i = 0; i < ctx->nknown_addr; i++) {
temp = &ctx->known_addrs[i];
if (latest == NULL ||
latest->last_recv_time < temp->last_recv_time) {
latest = temp;
}
if (now - temp->last_recv_time <= ADDR_TIMEOUT) {
total_not_timed_out++;
}
}
if (total_not_timed_out <= 1) {
load_addr(latest, &ctx->remote_addr, &ctx->remote_addrlen);
} else {
chosen = randombytes_uniform(total_not_timed_out);
total_not_timed_out = 0;
for (i = 0; i < ctx->nknown_addr; i++) {
temp = &ctx->known_addrs[i];
if (now - temp->last_recv_time <= ADDR_TIMEOUT) {
if (total_not_timed_out == chosen) {
load_addr(temp, &ctx->remote_addr, &ctx->remote_addrlen);
break;
}
total_not_timed_out++;
}
}
}
return 0;
}
int read_ModR_M(swaddr_t eip, Operand *rm, Operand *reg) {
ModR_M m;
m.val = instr_fetch(eip, 1);
// Log("m.val = %02x", m.val);
reg->type = OP_TYPE_REG;
reg->reg = m.reg;
if(m.mod == 3) {
rm->type = OP_TYPE_REG;
rm->reg = m.R_M;
switch(rm->size) {
case 1: rm->val = reg_b(m.R_M); break;
case 2: rm->val = reg_w(m.R_M); break;
case 4: rm->val = reg_l(m.R_M); break;
default: assert(0);
}
#ifdef DEBUG
switch(rm->size) {
case 1: sprintf(rm->str, "%%%s", regsb[m.R_M]); break;
case 2: sprintf(rm->str, "%%%s", regsw[m.R_M]); break;
case 4: sprintf(rm->str, "%%%s", regsl[m.R_M]); break;
}
#endif
return 1;
}
else {
int instr_len = load_addr(eip, &m, rm);
rm->val = swaddr_read(rm->addr, rm->size, R_DS); //TODO DS or SS
return instr_len;
}
}
DWORD
Read5(DWORD d)
{
word_20 p = 0;
load_addr(&p,d,5);
return p;
}
