moonlight-embedded/libgamestream/client.c

/*
 * This file is part of Moonlight Embedded.
 *
 * Copyright (C) 2015-2016 Iwan Timmer
 *
 * Moonlight is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Moonlight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Moonlight; if not, see <http://www.gnu.org/licenses/>.
 */

#include "http.h"
#include "xml.h"
#include "mkcert.h"
#include "client.h"
#include "errors.h"

#include <Limelight.h>

#include <sys/stat.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <uuid/uuid.h>
#include <openssl/sha.h>
#include <openssl/aes.h>
#include <openssl/rand.h>
#include <openssl/evp.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/err.h>

#define UNIQUE_FILE_NAME "uniqueid.dat"
#define P12_FILE_NAME "client.p12"

#define UNIQUEID_BYTES 8
#define UNIQUEID_CHARS (UNIQUEID_BYTES*2)

#define CHANNEL_COUNT_STEREO 2
#define CHANNEL_COUNT_51_SURROUND 6

#define CHANNEL_MASK_STEREO 0x3
#define CHANNEL_MASK_51_SURROUND 0xFC

static char unique_id[UNIQUEID_CHARS+1];
static X509 *cert;
static char cert_hex[4096];
static EVP_PKEY *privateKey;

const char* gs_error;

static int mkdirtree(const char* directory) {
  char buffer[1024];
  char* p = buffer;

  // The passed in string could be a string literal
  // so we must copy it first
  strcpy(p, directory);

  while (*p != 0) {
    // Find the end of the path element
    do {
      p++;
    } while (*p != 0 && *p != '/');

    char oldChar = *p;
    *p = 0;

    // Create the directory if it doesn't exist already
    if (mkdir(buffer, 0775) == -1 && errno != EEXIST) {
        return -1;
    }

    *p = oldChar;
  }

  return 0;
}

static int load_unique_id(const char* keyDirectory) {
  char uniqueFilePath[4096];
  sprintf(uniqueFilePath, "%s/%s", keyDirectory, UNIQUE_FILE_NAME);

  FILE *fd = fopen(uniqueFilePath, "r");
  if (fd == NULL) {
    unsigned char unique_data[UNIQUEID_BYTES];
    RAND_bytes(unique_data, UNIQUEID_BYTES);
    for (int i = 0; i < UNIQUEID_BYTES; i++) {
      sprintf(unique_id + (i * 2), "%02x", unique_data[i]);
    }
    fd = fopen(uniqueFilePath, "w");
    if (fd == NULL)
      return GS_FAILED;

    fwrite(unique_id, UNIQUEID_CHARS, 1, fd);
  } else {
    fread(unique_id, UNIQUEID_CHARS, 1, fd);
  }
  fclose(fd);
  unique_id[UNIQUEID_CHARS] = 0;

  return GS_OK;
}

static int load_cert(const char* keyDirectory) {
  char certificateFilePath[4096];
  sprintf(certificateFilePath, "%s/%s", keyDirectory, CERTIFICATE_FILE_NAME);

  char keyFilePath[4096];
  sprintf(&keyFilePath[0], "%s/%s", keyDirectory, KEY_FILE_NAME);

  FILE *fd = fopen(certificateFilePath, "r");
  if (fd == NULL) {
    printf("Generating certificate...");
    CERT_KEY_PAIR cert = mkcert_generate();
    printf("done\n");

    char p12FilePath[4096];
    sprintf(p12FilePath, "%s/%s", keyDirectory, P12_FILE_NAME);

    mkcert_save(certificateFilePath, p12FilePath, keyFilePath, cert);
    mkcert_free(cert);
    fd = fopen(certificateFilePath, "r");
  }

  if (fd == NULL) {
    gs_error = "Can't open certificate file";
    return GS_FAILED;
  }

  if (!(cert = PEM_read_X509(fd, NULL, NULL, NULL))) {
    gs_error = "Error loading cert into memory";
    return GS_FAILED;
  }

  rewind(fd);

  int c;
  int length = 0;
  while ((c = fgetc(fd)) != EOF) {
    sprintf(cert_hex + length, "%02x", c);
    length += 2;
  }
  cert_hex[length] = 0;

  fclose(fd);

  fd = fopen(keyFilePath, "r");
  if (fd == NULL) {
    gs_error = "Error loading key into memory";
    return GS_FAILED;
  }

  PEM_read_PrivateKey(fd, &privateKey, NULL, NULL);
  fclose(fd);

  return GS_OK;
}

static int load_server_status(PSERVER_DATA server) {

  uuid_t uuid;
  char uuid_str[37];

  int ret;
  char url[4096];
  int i;

  i = 0;
  do {
    char *pairedText = NULL;
    char *currentGameText = NULL;
    char *versionText = NULL;
    char *stateText = NULL;
    char *heightText = NULL;
    char *serverCodecModeSupportText = NULL;

    ret = GS_INVALID;

    uuid_generate_random(uuid);
    uuid_unparse(uuid, uuid_str);

    // Modern GFE versions don't allow serverinfo to be fetched over HTTPS if the client
    // is not already paired. Since we can't pair without knowing the server version, we
    // make another request over HTTP if the HTTPS request fails. We can't just use HTTP
    // for everything because it doesn't accurately tell us if we're paired.
    sprintf(url, "%s://%s:%d/serverinfo?uniqueid=%s&uuid=%s",
      i == 0 ? "https" : "http", server->address, i == 0 ? 47984 : 47989, unique_id, uuid_str);

    PHTTP_DATA data = http_create_data();
    if (data == NULL) {
      ret = GS_OUT_OF_MEMORY;
      goto cleanup;
    }
    if (http_request(url, data) != GS_OK) {
      ret = GS_IO_ERROR;
      goto cleanup;
    }

    if (xml_search(data->memory, data->size, "currentgame", &currentGameText) != GS_OK) {
      goto cleanup;
    }

    if (xml_search(data->memory, data->size, "PairStatus", &pairedText) != GS_OK)
      goto cleanup;

    if (xml_search(data->memory, data->size, "appversion", &versionText) != GS_OK)
      goto cleanup;

    if (xml_search(data->memory, data->size, "state", &stateText) != GS_OK)
      goto cleanup;

    if (xml_search(data->memory, data->size, "Height", &heightText) != GS_OK)
      goto cleanup;

    if (xml_search(data->memory, data->size, "ServerCodecModeSupport", &serverCodecModeSupportText) != GS_OK)
      goto cleanup;

    if (xml_search(data->memory, data->size, "gputype", &server->gpuType) != GS_OK)
      goto cleanup;

    if (xml_search(data->memory, data->size, "GfeVersion", &server->gfeVersion) != GS_OK)
      goto cleanup;

    // These fields are present on all version of GFE that this client supports
    if (!strlen(currentGameText) || !strlen(pairedText) || !strlen(versionText) || !strlen(stateText))
      goto cleanup;

    server->paired = pairedText != NULL && strcmp(pairedText, "1") == 0;
    server->currentGame = currentGameText == NULL ? 0 : atoi(currentGameText);
    server->supports4K = heightText != NULL && serverCodecModeSupportText != NULL && atoi(heightText) >= 2160;
    server->serverMajorVersion = atoi(versionText);
    if (strstr(stateText, "_SERVER_AVAILABLE")) {
      // After GFE 2.8, current game remains set even after streaming
      // has ended. We emulate the old behavior by forcing it to zero
      // if streaming is not active.
      server->currentGame = 0;
    }
    ret = GS_OK;

    cleanup:
    if (data != NULL)
      http_free_data(data);

    if (pairedText != NULL)
      free(pairedText);

    if (currentGameText != NULL)
      free(currentGameText);

    if (versionText != NULL)
      free(versionText);

    if (heightText != NULL)
      free(heightText);

    if (serverCodecModeSupportText != NULL)
      free(serverCodecModeSupportText);

    i++;
  } while (ret != GS_OK && i < 2);

  return ret;
}

static void bytes_to_hex(unsigned char *in, char *out, size_t len) {
  for (int i = 0; i < len; i++) {
    sprintf(out + i * 2, "%02x", in[i]);
  }
  out[len * 2] = 0;
}

static int sign_it(const char *msg, size_t mlen, unsigned char **sig, size_t *slen, EVP_PKEY *pkey) {
  int result = GS_FAILED;

  *sig = NULL;
  *slen = 0;

  EVP_MD_CTX *ctx = EVP_MD_CTX_create();
  if (ctx == NULL)
    return GS_FAILED;

  const EVP_MD *md = EVP_get_digestbyname("SHA256");
  if (md == NULL)
    goto cleanup;

  int rc = EVP_DigestInit_ex(ctx, md, NULL);
  if (rc != 1)
    goto cleanup;

  rc = EVP_DigestSignInit(ctx, NULL, md, NULL, pkey);
  if (rc != 1)
    goto cleanup;

  rc = EVP_DigestSignUpdate(ctx, msg, mlen);
  if (rc != 1)
    goto cleanup;

  size_t req = 0;
  rc = EVP_DigestSignFinal(ctx, NULL, &req);
  if (rc != 1 || !(req > 0))
    goto cleanup;

  *sig = OPENSSL_malloc(req);
  if (*sig == NULL)
    goto cleanup;

  *slen = req;
  rc = EVP_DigestSignFinal(ctx, *sig, slen);
  if (rc != 1 || req != *slen)
    goto cleanup;

  result = GS_OK;

  cleanup:
  EVP_MD_CTX_destroy(ctx);
  ctx = NULL;

  return result;
}

static bool verifySignature(const char *data, int dataLength, const char *signature, int signatureLength, const char *cert) {
    X509* x509;
    BIO* bio = BIO_new(BIO_s_mem());
    BIO_puts(bio, cert);
    x509 = PEM_read_bio_X509(bio, NULL, NULL, NULL);
    
    BIO_free(bio);
    
    if (!x509) {
        printf("Invalid certificate\n");
        return false;
    }
    
    EVP_PKEY* pubKey = X509_get_pubkey(x509);
    EVP_MD_CTX *mdctx = NULL;
    mdctx = EVP_MD_CTX_create();
    EVP_DigestVerifyInit(mdctx, NULL, EVP_sha256(), NULL, pubKey);
    EVP_DigestVerifyUpdate(mdctx, data, dataLength);
    int result = EVP_DigestVerifyFinal(mdctx, signature, signatureLength);
    
    X509_free(x509);
    EVP_PKEY_free(pubKey);
    EVP_MD_CTX_destroy(mdctx);
    printf("%d/%d = %d\n", dataLength, signatureLength, result);
    
    return result > 0;
}

int gs_unpair(PSERVER_DATA server) {
  int ret = GS_OK;
  char url[4096];
  uuid_t uuid;
  char uuid_str[37];
  PHTTP_DATA data = http_create_data();
  if (data == NULL)
    return GS_OUT_OF_MEMORY;

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "http://%s:47989/unpair?uniqueid=%s&uuid=%s", server->address, unique_id, uuid_str);
  ret = http_request(url, data);

  http_free_data(data);
  return ret;
}

int gs_pair(PSERVER_DATA server, char* pin) {
  int ret = GS_OK;
  char* result = NULL;
  char url[4096];
  uuid_t uuid;
  char uuid_str[37];

  if (server->paired) {
    gs_error = "Already paired";
    return GS_WRONG_STATE;
  }

  if (server->currentGame != 0) {
    gs_error = "The computer is currently in a game. You must close the game before pairing";
    return GS_WRONG_STATE;
  }

  unsigned char salt_data[16];
  char salt_hex[33];
  RAND_bytes(salt_data, 16);
  bytes_to_hex(salt_data, salt_hex, 16);

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "http://%s:47989/pair?uniqueid=%s&uuid=%s&devicename=roth&updateState=1&phrase=getservercert&salt=%s&clientcert=%s", server->address, unique_id, uuid_str, salt_hex, cert_hex);
  PHTTP_DATA data = http_create_data();
  if (data == NULL)
    return GS_OUT_OF_MEMORY;
  else if ((ret = http_request(url, data)) != GS_OK)
    goto cleanup;

  if ((ret = xml_search(data->memory, data->size, "paired", &result)) != GS_OK)
    goto cleanup;

  if (strcmp(result, "1") != 0) {
    gs_error = "Pairing failed";
    ret = GS_FAILED;
    goto cleanup;
  }

  free(result);
  result = NULL;
  if ((ret = xml_search(data->memory, data->size, "plaincert", &result)) != GS_OK)
    goto cleanup;

  if (strlen(result)/2 > 8191) {
    gs_error = "Server certificate too big";
    ret = GS_FAILED;
    goto cleanup;
  }

  char plaincert[8192];
  for (int count = 0; count < strlen(result); count += 2) {
    sscanf(&result[count], "%2hhx", &plaincert[count / 2]);
  }
  plaincert[strlen(result)/2] = '\0';
  printf("%d / %d\n", strlen(result)/2, strlen(plaincert));

  unsigned char salt_pin[20];
  unsigned char aes_key_hash[32];
  AES_KEY enc_key, dec_key;
  memcpy(salt_pin, salt_data, 16);
  memcpy(salt_pin+16, pin, 4);

  int hash_length = server->serverMajorVersion >= 7 ? 32 : 20;
  if (server->serverMajorVersion >= 7)
    SHA256(salt_pin, 20, aes_key_hash);
  else
    SHA1(salt_pin, 20, aes_key_hash);

  AES_set_encrypt_key((unsigned char *)aes_key_hash, 128, &enc_key);
  AES_set_decrypt_key((unsigned char *)aes_key_hash, 128, &dec_key);

  unsigned char challenge_data[16];
  unsigned char challenge_enc[16];
  char challenge_hex[33];
  RAND_bytes(challenge_data, 16);
  AES_encrypt(challenge_data, challenge_enc, &enc_key);
  bytes_to_hex(challenge_enc, challenge_hex, 16);

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "http://%s:47989/pair?uniqueid=%s&uuid=%s&devicename=roth&updateState=1&clientchallenge=%s", server->address, unique_id, uuid_str, challenge_hex);
  if ((ret = http_request(url, data)) != GS_OK)
    goto cleanup;

  free(result);
  result = NULL;
  if ((ret = xml_search(data->memory, data->size, "paired", &result)) != GS_OK)
    goto cleanup;

  if (strcmp(result, "1") != 0) {
    gs_error = "Pairing failed";
    ret = GS_FAILED;
    goto cleanup;
  }

  free(result);
  result = NULL;
  if (xml_search(data->memory, data->size, "challengeresponse", &result) != GS_OK) {
    ret = GS_INVALID;
    goto cleanup;
  }

  char challenge_response_data_enc[48];
  char challenge_response_data[48];
  for (int count = 0; count < strlen(result); count += 2) {
    sscanf(&result[count], "%2hhx", &challenge_response_data_enc[count / 2]);
  }

  for (int i = 0; i < 48; i += 16) {
    AES_decrypt(&challenge_response_data_enc[i], &challenge_response_data[i], &dec_key);
  }

  char client_secret_data[16];
  RAND_bytes(client_secret_data, 16);

  char challenge_response[16 + 256 + 16];
  char challenge_response_hash[32];
  char challenge_response_hash_enc[32];
  char challenge_response_hex[65];
  memcpy(challenge_response, challenge_response_data + hash_length, 16);
  memcpy(challenge_response + 16, cert->signature->data, 256);
  memcpy(challenge_response + 16 + 256, client_secret_data, 16);
  if (server->serverMajorVersion >= 7)
    SHA256(challenge_response, 16 + 256 + 16, challenge_response_hash);
  else
    SHA1(challenge_response, 16 + 256 + 16, challenge_response_hash);

  for (int i = 0; i < 32; i += 16) {
    AES_encrypt(&challenge_response_hash[i], &challenge_response_hash_enc[i], &enc_key);
  }
  bytes_to_hex(challenge_response_hash_enc, challenge_response_hex, 32);

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "http://%s:47989/pair?uniqueid=%s&uuid=%s&devicename=roth&updateState=1&serverchallengeresp=%s", server->address, unique_id, uuid_str, challenge_response_hex);
  if ((ret = http_request(url, data)) != GS_OK)
    goto cleanup;

  free(result);
  result = NULL;
  if ((ret = xml_search(data->memory, data->size, "paired", &result)) != GS_OK)
    goto cleanup;

  if (strcmp(result, "1") != 0) {
    gs_error = "Pairing failed";
    ret = GS_FAILED;
    goto cleanup;
  }

  free(result);
  result = NULL;
  if (xml_search(data->memory, data->size, "pairingsecret", &result) != GS_OK) {
    ret = GS_INVALID;
    goto cleanup;
  }

  char pairing_secret[16 + 256];
  for (int count = 0; count < strlen(result); count += 2) {
    sscanf(&result[count], "%2hhx", &pairing_secret[count / 2]);
  }

  if (!verifySignature(pairing_secret, 16, pairing_secret+16, 256, plaincert)) {
    gs_error = "MITM attack detected";
    ret = GS_FAILED;
    goto cleanup;
  }

  unsigned char *signature = NULL;
  size_t s_len;
  if (sign_it(client_secret_data, 16, &signature, &s_len, privateKey) != GS_OK) {
      gs_error = "Failed to sign data";
      ret = GS_FAILED;
      goto cleanup;
  }

  char client_pairing_secret[16 + 256];
  char client_pairing_secret_hex[(16 + 256) * 2 + 1];
  memcpy(client_pairing_secret, client_secret_data, 16);
  memcpy(client_pairing_secret + 16, signature, 256);
  bytes_to_hex(client_pairing_secret, client_pairing_secret_hex, 16 + 256);

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "http://%s:47989/pair?uniqueid=%s&uuid=%s&devicename=roth&updateState=1&clientpairingsecret=%s", server->address, unique_id, uuid_str, client_pairing_secret_hex);
  if ((ret = http_request(url, data)) != GS_OK)
    goto cleanup;

  free(result);
  result = NULL;
  if ((ret = xml_search(data->memory, data->size, "paired", &result)) != GS_OK)
    goto cleanup;

  if (strcmp(result, "1") != 0) {
    gs_error = "Pairing failed";
    ret = GS_FAILED;
    goto cleanup;
  }

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "https://%s:47984/pair?uniqueid=%s&uuid=%s&devicename=roth&updateState=1&phrase=pairchallenge", server->address, unique_id, uuid_str);
  if ((ret = http_request(url, data)) != GS_OK)
    goto cleanup;

  free(result);
  result = NULL;
  if ((ret = xml_search(data->memory, data->size, "paired", &result)) != GS_OK)
    goto cleanup;

  if (strcmp(result, "1") != 0) {
    gs_error = "Pairing failed";
    ret = GS_FAILED;
    goto cleanup;
  }

  server->paired = true;

  cleanup:
  if (ret != GS_OK)
    gs_unpair(server);
  
  if (result != NULL)
    free(result);

  http_free_data(data);

  return ret;
}

int gs_applist(PSERVER_DATA server, PAPP_LIST *list) {
  int ret = GS_OK;
  char url[4096];
  uuid_t uuid;
  char uuid_str[37];
  PHTTP_DATA data = http_create_data();
  if (data == NULL)
    return GS_OUT_OF_MEMORY;

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "https://%s:47984/applist?uniqueid=%s&uuid=%s", server->address, unique_id, uuid_str);
  if (http_request(url, data) != GS_OK)
    ret = GS_IO_ERROR;
  else if (xml_applist(data->memory, data->size, list) != GS_OK)
    ret = GS_INVALID;

  http_free_data(data);
  return ret;
}

int gs_start_app(PSERVER_DATA server, STREAM_CONFIGURATION *config, int appId, bool sops, bool localaudio) {
  int ret = GS_OK;
  uuid_t uuid;
  char* result = NULL;
  char uuid_str[37];

  if (config->height >= 2160 && !server->supports4K)
    return GS_NOT_SUPPORTED_4K;

  RAND_bytes(config->remoteInputAesKey, 16);
  memset(config->remoteInputAesIv, 0, 16);

  srand(time(NULL));
  char url[4096];
  u_int32_t rikeyid = 0;
  char rikey_hex[33];
  bytes_to_hex(config->remoteInputAesKey, rikey_hex, 16);

  PHTTP_DATA data = http_create_data();
  if (data == NULL)
    return GS_OUT_OF_MEMORY;

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  if (server->currentGame == 0) {
    int channelCounnt = config->audioConfiguration == AUDIO_CONFIGURATION_STEREO ? CHANNEL_COUNT_STEREO : CHANNEL_COUNT_51_SURROUND;
    int mask = config->audioConfiguration == AUDIO_CONFIGURATION_STEREO ? CHANNEL_MASK_STEREO : CHANNEL_MASK_51_SURROUND;
    sprintf(url, "https://%s:47984/launch?uniqueid=%s&uuid=%s&appid=%d&mode=%dx%dx%d&additionalStates=1&sops=%d&rikey=%s&rikeyid=%d&localAudioPlayMode=%d&surroundAudioInfo=%d", server->address, unique_id, uuid_str, appId, config->width, config->height, config->fps, sops, rikey_hex, rikeyid, localaudio, (mask << 16) + channelCounnt);
  } else
    sprintf(url, "https://%s:47984/resume?uniqueid=%s&uuid=%s&rikey=%s&rikeyid=%d", server->address, unique_id, uuid_str, rikey_hex, rikeyid);

  if ((ret = http_request(url, data)) == GS_OK)
    server->currentGame = appId;
  else
    goto cleanup;

  if ((ret = xml_search(data->memory, data->size, "gamesession", &result)) != GS_OK)
    goto cleanup;

  if (!strcmp(result, "0")) {
    ret = GS_FAILED;
    goto cleanup;
  }

  cleanup:
  if (result != NULL)
    free(result);

  http_free_data(data);
  return ret;
}

int gs_quit_app(PSERVER_DATA server) {
  int ret = GS_OK;
  char url[4096];
  uuid_t uuid;
  char uuid_str[37];
  char* result = NULL;
  PHTTP_DATA data = http_create_data();
  if (data == NULL)
    return GS_OUT_OF_MEMORY;

  uuid_generate_random(uuid);
  uuid_unparse(uuid, uuid_str);
  sprintf(url, "https://%s:47984/cancel?uniqueid=%s&uuid=%s", server->address, unique_id, uuid_str);
  if ((ret = http_request(url, data)) != GS_OK)
    goto cleanup;

  if ((ret = xml_search(data->memory, data->size, "cancel", &result)) != GS_OK)
    goto cleanup;

  if (strcmp(result, "0") == 0) {
    ret = GS_FAILED;
    goto cleanup;
  }

  cleanup:
  if (result != NULL)
    free(result);

  http_free_data(data);
  return ret;
}

int gs_init(PSERVER_DATA server, const char *keyDirectory) {
  mkdirtree(keyDirectory);
  if (load_unique_id(keyDirectory) != GS_OK)
    return GS_FAILED;

  if (load_cert(keyDirectory))
    return GS_FAILED;

  http_init(keyDirectory);
  return load_server_status(server);
}