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#include <fstream>
#include <filesystem>
#include <unordered_map>
#include <mutex>
#include <thread>
#include <memory>
#include <cstdlib>
#include "handler.h"
using namespace std;
static string shell_escape(const string &str) {
string res;
res.reserve(str.size() + 16);
res += '\'';
for (char c : str) {
if (c == '\'') res += "'\"'\"'";
else res += c;
}
res += '\'';
return res;
}
static string read_file(const string &fname) {
ifstream f(fname);
if (!f) return {};
string contents;
char buffer[4096];
while (true) {
f.read(buffer, sizeof buffer);
contents.insert(contents.size(), buffer, f.gcount());
if (!f) break;
}
return contents;
}
static string download_url(const string &url) {
string tempdir_name = "/tmp/tmp.url_handler.XXXXXX";
if (mkdtemp(tempdir_name.data()) == nullptr) {
perror("mkdtemp");
return {};
}
string tempfile_name = tempdir_name + "/file";
string cmd = "curl -sL " + shell_escape(url) + " >" + shell_escape(tempfile_name);
// fprintf(stderr, "cmd = %s\n", cmd.data());
system(cmd.data());
string response = read_file(tempfile_name);
filesystem::remove_all(tempdir_name);
fprintf(stderr, "Received response for url '%s'\n", url.data());
return response;
}
struct State {
string url;
thread download_thread;
// mutex protects 'response' and 'response_present'; the download thread
// sets 'response_present' to true and simultaneously 'response' to the
// right value. After 'response_present' can be observed to be true by the
// main thread, the download thread doesn't touch anything anymore.
mutex res_mt;
bool response_present = false;
string response;
// owned by host thread
size_t rescur = 0;
};
static unordered_map<uint32_t, unique_ptr<State>> state_map;
uint16_t handle_icmp(uint32_t source_addr, const array<uint8_t, 16> &payload) {
auto state_it = state_map.find(source_addr);
if (state_it == state_map.end()) {
state_it = state_map.emplace(source_addr, make_unique<State>()).first;
}
State &state = *state_it->second;
switch (payload[0]) {
case 100: // url fragment
// fprintf(stderr, "msg(%u): url fragment\n", source_addr);
{
lock_guard<mutex> guard(state.res_mt);
if (state.response_present) return 0;
}
for (size_t i = 1; i < 16; i++) {
if (payload[i] == '\0') {
fprintf(stderr, "URL received: <%s>\n", state.url.data());
state.download_thread = thread([&state]() {
string response = download_url(state.url);
{
lock_guard<mutex> guard(state.res_mt);
state.response = move(response);
state.response_present = true;
}
// fprintf(stderr, "[dlth] response received: <%s>\n", state.response.data());
});
break;
}
state.url.push_back(payload[i]);
}
return 1;
case 101: { // query whether response is ready
// fprintf(stderr, "msg(%u): ready query\n", source_addr);
lock_guard<mutex> guard(state.res_mt);
return state.response_present ? 1 : 0;
}
case 102: { // get response
// fprintf(stderr, "msg(%u): get_response\n", source_addr);
{
lock_guard<mutex> guard(state.res_mt);
if (!state.response_present) return 0;
}
uint16_t retval = 0;
for (size_t i = 0; i < 2 && state.rescur < state.response.size(); i++) {
retval |= (uint16_t)state.response[state.rescur] << (8 * i);
state.rescur++;
}
if (state.rescur == state.response.size()) {
state.download_thread.join(); // should already have exited
state_map.erase(state_it);
}
// fprintf(stderr, " -> retval %016X\n", (unsigned)retval);
return retval;
}
}
return 0;
}
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