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#include "packet.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <err.h>
#include <poll.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdbool.h>
struct proc {
pid_t pid;
int fds[2];
};
static void
close_fd(int *fd)
{
if (*fd >= 0)
close(*fd);
}
static void
proc_close(struct proc *proc)
{
if (proc->pid)
waitpid(proc->pid, NULL, 0);
close_fd(&proc->fds[0]);
close_fd(&proc->fds[1]);
*proc = (struct proc){0};
}
static bool
proc_open(const char *file, char *const argv[], struct proc *out_proc)
{
*out_proc = (struct proc){0};
int pipes[4];
if (pipe(&pipes[0]) != 0 || pipe(&pipes[2]) != 0 ) {
proc_close(out_proc);
return false;
}
if ((out_proc->pid = fork()) > 0) {
out_proc->fds[0] = pipes[3];
out_proc->fds[1] = pipes[0];
close(pipes[1]);
close(pipes[2]);
return true;
} else {
close(pipes[0]);
close(pipes[3]);
dup2(pipes[2], 0);
dup2(pipes[1], 1);
close(pipes[2]);
close(pipes[1]);
execvp(file, argv);
_exit(0);
}
out_proc->fds[0] = pipes[3];
out_proc->fds[1] = pipes[0];
close(pipes[1]);
close(pipes[2]);
return true;
}
static size_t
safe_read(int fd, void *dst, const size_t dst_size)
{
size_t off = 0;
ssize_t ret = 0;
for (; off < dst_size && (ret = read(fd, (char*)dst + off, dst_size - off)) > 0; off += ret);
return (ret < 0 ? 0 : off);
}
static void
dump_packet(const uint8_t *bytes, const size_t sz, const char *prefix, const uint16_t type)
{
const char *local = getenv("TCPLOCALPORT");
char path[4096];
snprintf(path, sizeof(path), "packets/%s-%s-0x%.4x.raw", local, prefix, type);
FILE *f;
if (!(f = fopen(path, "wb")))
err(EXIT_FAILURE, "fopen");
if (fwrite(bytes, 1, sz, f) != sz)
err(EXIT_FAILURE, "fwrite");
fclose(f);
}
static void
handle_select_character_res(union packet *packet, bool prologue)
{
packet->hdr.type = (prologue ? PACKET_CHARACTER_ENTER_PROLOGUE : PACKET_SELECT_CHARACTER_RES);
struct pbuf pbuf = { .packet = packet, .cursor = sizeof(packet->hdr) };
pbuf.cursor += sizeof(uint32_t);
for (size_t i = 0; i < 32; ++i) pbuf_write(&pbuf, (uint8_t[]){0xff}, 1);
const char *server_ip = getenv("SERVER_IP");
server_ip = (server_ip ? server_ip : "127.0.0.1");
pbuf_write_str(&pbuf, server_ip);
pbuf_write(&pbuf, (uint16_t[]){10100}, sizeof(uint16_t));
for (size_t i = 0; i < 38; ++i) pbuf_write(&pbuf, (uint8_t[]){0x00}, 1);
pbuf_flush(&pbuf);
}
static void
handle_character_enter_prologue(union packet *packet)
{
handle_select_character_res(packet, true);
}
static void
handle_server_list(union packet *packet)
{
struct pbuf pbuf = { .packet = packet, .cursor = sizeof(packet->hdr) };
pbuf_write(&pbuf, (uint8_t[]){0x00, 0x01, 0x00, 0x00}, 4);
pbuf_write(&pbuf, (uint16_t[]){10000}, sizeof(uint16_t));
pbuf_write_str(&pbuf, "benis");
const char *server_ip = getenv("SERVER_IP");
server_ip = (server_ip ? server_ip : "127.0.0.1");
pbuf_write_str(&pbuf, server_ip);
pbuf_write(&pbuf, (uint8_t[]){0x01, 0x00, 0x00, 0x00, 0x9f, 0x01, 0x00, 0x00, 0x00}, 9);
pbuf_flush(&pbuf);
}
static bool
intercept(union packet *packet)
{
packet_crypt(packet);
bool ret = true;
switch (packet->hdr.type) {
case PACKET_SERVER_LIST:
handle_server_list(packet);
break;
case PACKET_SELECT_CHARACTER_RES:
handle_select_character_res(packet, false);
break;
case PACKET_CHARACTER_ENTER_PROLOGUE:
handle_character_enter_prologue(packet);
break;
default:
ret = false;
break;
}
packet_crypt(packet);
return ret;
}
static uint16_t
decrypted_packet_type(union packet *packet)
{
const uint16_t size = packet->hdr.size;
packet->hdr.size = sizeof(packet->hdr);
packet_crypt(packet);
const uint16_t type = packet->hdr.type;
packet_crypt(packet);
packet->hdr.size = size;
return type;
}
int
main(int argc, char *const argv[])
{
for (int i = 1; i < argc; ++i) {
if (!strcmp(argv[i], "--help") || !strcmp(argv[i], "-h"))
errx(EXIT_SUCCESS, "usage: %s cmd [args]", argv[0]);
}
struct proc server = {0};
if (argc >= 2 && !proc_open(argv[1], argv + 1, &server))
errx(EXIT_FAILURE, "failed to execute: %s", argv[1]);
setvbuf(stdout, NULL, _IONBF, 0);
struct pollfd pfd[] = {
{ .fd = STDIN_FILENO, .events = POLLIN },
{ .fd = server.fds[1], .events = POLLIN },
};
union packet packet;
while (poll(pfd, 1 + !!server.pid, -1) > 0) {
if (pfd[0].revents & POLLIN) {
if (fread(packet.buf, 1, sizeof(packet.hdr), stdin) < sizeof(packet.hdr))
errx(EXIT_SUCCESS, "client close");
if (!packet_verify(&packet)) {
for (size_t i = 0; i < 7; ++i) fprintf(stderr, "%.2x ", packet.buf[i]);
errx(EXIT_FAILURE, "invalid packet");
}
if (fread(packet.buf + sizeof(packet.hdr), 1, packet.hdr.size - sizeof(packet.hdr), stdin) != packet.hdr.size - sizeof(packet.hdr))
errx(EXIT_SUCCESS, "failed to read packet from client");
const uint16_t type = decrypted_packet_type(&packet);
dump_packet(packet.buf, packet.hdr.size, "client", type);
if (intercept(&packet)) {
dump_packet(packet.buf, packet.hdr.size, "client-intercepted", type);
warnx("intercepted client packet 0x%.4x", type);
} else {
warnx("client packet 0x%.4x (%u)",type, packet.hdr.size);
}
if (server.pid && write(server.fds[0], packet.buf, packet.hdr.size) != packet.hdr.size)
err(EXIT_FAILURE, "failed to write to server");
} else if (pfd[1].revents & POLLIN) {
if (read(server.fds[1], packet.buf, sizeof(packet.hdr)) < (ssize_t)sizeof(packet.hdr))
errx(EXIT_SUCCESS, "server close");
if (!packet_verify(&packet)) {
for (size_t i = 0; i < 7; ++i) fprintf(stderr, "%.2x ", packet.buf[i]);
errx(EXIT_FAILURE, "invalid packet");
}
if (safe_read(server.fds[1], packet.buf + sizeof(packet.hdr), packet.hdr.size - sizeof(packet.hdr)) != (packet.hdr.size - sizeof(packet.hdr)))
errx(EXIT_SUCCESS, "failed to read packet from server");
const uint16_t type = decrypted_packet_type(&packet);
dump_packet(packet.buf, packet.hdr.size, "server", type);
if (intercept(&packet)) {
dump_packet(packet.buf, packet.hdr.size, "server-intercepted", type);
warnx("intercepted server packet 0x%.4x",type);
} else {
warnx("server packet 0x%.4x (%u)", type, packet.hdr.size);
}
if (fwrite(packet.buf, 1, packet.hdr.size, stdout) != packet.hdr.size)
err(EXIT_FAILURE, "failed to write to client");
}
}
proc_close(&server);
return EXIT_SUCCESS;
}
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