mongoose.c

  mg_fclose(filep);
}

void mg_send_file(struct mg_connection *conn, const char *path) {
  struct file file = STRUCT_FILE_INITIALIZER;
  if (mg_stat(conn, path, &file)) {
    handle_file_request(conn, path, &file);
  } else {
    send_http_error(conn, 404, "Not Found", "%s", "File not found");
  }
}


// Parse HTTP headers from the given buffer, advance buffer to the point
// where parsing stopped.
static void parse_http_headers(char **buf, struct mg_request_info *ri) {
  int i;

  for (i = 0; i < (int) ARRAY_SIZE(ri->http_headers); i++) {
    ri->http_headers[i].name = skip_quoted(buf, ":", " ", 0);
    ri->http_headers[i].value = skip(buf, "\r\n");
    if (ri->http_headers[i].name[0] == '\0')
      break;
    ri->num_headers = i + 1;
  }
}

static int is_valid_http_method(const char *method) {
  return !strcmp(method, "GET") || !strcmp(method, "POST") ||
    !strcmp(method, "HEAD") || !strcmp(method, "CONNECT") ||
    !strcmp(method, "PUT") || !strcmp(method, "DELETE") ||
    !strcmp(method, "OPTIONS") || !strcmp(method, "PROPFIND")
    || !strcmp(method, "MKCOL")
          ;
}

// Parse HTTP request, fill in mg_request_info structure.
// This function modifies the buffer by NUL-terminating
// HTTP request components, header names and header values.
static int parse_http_message(char *buf, int len, struct mg_request_info *ri) {
  int is_request, request_length = get_request_len(buf, len);
  if (request_length > 0) {
    // Reset attributes. DO NOT TOUCH is_ssl, remote_ip, remote_port
    ri->remote_user = ri->request_method = ri->uri = ri->http_version = NULL;
    ri->num_headers = 0;

    buf[request_length - 1] = '\0';

    // RFC says that all initial whitespaces should be ingored
    while (*buf != '\0' && isspace(* (unsigned char *) buf)) {
      buf++;
    }
    ri->request_method = skip(&buf, " ");
    ri->uri = skip(&buf, " ");
    ri->http_version = skip(&buf, "\r\n");
    if (((is_request = is_valid_http_method(ri->request_method)) &&
         memcmp(ri->http_version, "HTTP/", 5) != 0) ||
        (!is_request && memcmp(ri->request_method, "HTTP/", 5)) != 0) {
      request_length = -1;
    } else {
      if (is_request) {
        ri->http_version += 5;
      }
      parse_http_headers(&buf, ri);
    }
  }
  return request_length;
}

// Keep reading the input (either opened file descriptor fd, or socket sock,
// or SSL descriptor ssl) into buffer buf, until \r\n\r\n appears in the
// buffer (which marks the end of HTTP request). Buffer buf may already
// have some data. The length of the data is stored in nread.
// Upon every read operation, increase nread by the number of bytes read.
static int read_request(FILE *fp, struct mg_connection *conn,
                        char *buf, int bufsiz, int *nread) {
  int request_len, n = 0;

  request_len = get_request_len(buf, *nread);
  while (conn->ctx->stop_flag == 0 &&
         *nread < bufsiz && request_len == 0 &&
         (n = pull(fp, conn, buf + *nread, bufsiz - *nread)) > 0) {
    *nread += n;
    assert(*nread <= bufsiz);
    request_len = get_request_len(buf, *nread);
  }

  return request_len <= 0 && n <= 0 ? -1 : request_len;
}

// For given directory path, substitute it to valid index file.
// Return 0 if index file has been found, -1 if not found.
// If the file is found, it's stats is returned in stp.
static int substitute_index_file(struct mg_connection *conn, char *path,
                                 size_t path_len, struct file *filep) {
  const char *list = conn->ctx->config[INDEX_FILES];
  struct file file = STRUCT_FILE_INITIALIZER;
  struct vec filename_vec;
  size_t n = strlen(path);
  int found = 0;

  // The 'path' given to us points to the directory. Remove all trailing
  // directory separator characters from the end of the path, and
  // then append single directory separator character.
  while (n > 0 && path[n - 1] == '/') {
    n--;
  }
  path[n] = '/';

  // Traverse index files list. For each entry, append it to the given
  // path and see if the file exists. If it exists, break the loop
  while ((list = next_option(list, &filename_vec, NULL)) != NULL) {

    // Ignore too long entries that may overflow path buffer
    if (filename_vec.len > path_len - (n + 2))
      continue;

    // Prepare full path to the index file
    mg_strlcpy(path + n + 1, filename_vec.ptr, filename_vec.len + 1);

    // Does it exist?
    if (mg_stat(conn, path, &file)) {
      // Yes it does, break the loop
      *filep = file;
      found = 1;
      break;
    }
  }

  // If no index file exists, restore directory path
  if (!found) {
    path[n] = '\0';
  }

  return found;
}

// Return True if we should reply 304 Not Modified.
static int is_not_modified(const struct mg_connection *conn,
                           const struct file *filep) {
  char etag[64];
  const char *ims = mg_get_header(conn, "If-Modified-Since");
  const char *inm = mg_get_header(conn, "If-None-Match");
  construct_etag(etag, sizeof(etag), filep);
  return (inm != NULL && !mg_strcasecmp(etag, inm)) ||
    (ims != NULL && filep->modification_time <= parse_date_string(ims));
}

static int forward_body_data(struct mg_connection *conn, FILE *fp,
                             SOCKET sock, SSL *ssl) {
  const char *expect, *body;
  char buf[MG_BUF_LEN];
  int to_read, nread, buffered_len, success = 0;

  expect = mg_get_header(conn, "Expect");
  assert(fp != NULL);

  if (conn->content_len == -1) {
    send_http_error(conn, 411, "Length Required", "%s", "");
  } else if (expect != NULL && mg_strcasecmp(expect, "100-continue")) {
    send_http_error(conn, 417, "Expectation Failed", "%s", "");
  } else {
    if (expect != NULL) {
      (void) mg_printf(conn, "%s", "HTTP/1.1 100 Continue\r\n\r\n");
    }

    body = conn->buf + conn->request_len + conn->consumed_content;
    buffered_len = &conn->buf[conn->data_len] - body;
    assert(buffered_len >= 0);
    assert(conn->consumed_content == 0);

    if (buffered_len > 0) {
      if ((int64_t) buffered_len > conn->content_len) {
        buffered_len = (int) conn->content_len;
      }
      push(fp, sock, ssl, body, (int64_t) buffered_len);
      conn->consumed_content += buffered_len;
    }

    nread = 0;
    while (conn->consumed_content < conn->content_len) {
      to_read = sizeof(buf);
      if ((int64_t) to_read > conn->content_len - conn->consumed_content) {
        to_read = (int) (conn->content_len - conn->consumed_content);
      }
      nread = pull(NULL, conn, buf, to_read);
      if (nread <= 0 || push(fp, sock, ssl, buf, nread) != nread) {
        break;
      }
      conn->consumed_content += nread;
    }

    if (conn->consumed_content == conn->content_len) {
      success = nread >= 0;
    }

    // Each error code path in this function must send an error
    if (!success) {
      send_http_error(conn, 577, http_500_error, "%s", "");
    }
  }

  return success;
}

#if !defined(NO_CGI)
// This structure helps to create an environment for the spawned CGI program.
// Environment is an array of "VARIABLE=VALUE\0" ASCIIZ strings,
// last element must be NULL.
// However, on Windows there is a requirement that all these VARIABLE=VALUE\0
// strings must reside in a contiguous buffer. The end of the buffer is
// marked by two '\0' characters.
// We satisfy both worlds: we create an envp array (which is vars), all
// entries are actually pointers inside buf.
struct cgi_env_block {
  struct mg_connection *conn;
  char buf[CGI_ENVIRONMENT_SIZE]; // Environment buffer
  int len; // Space taken
  char *vars[MAX_CGI_ENVIR_VARS]; // char **envp
  int nvars; // Number of variables
};

static char *addenv(struct cgi_env_block *block,
                    PRINTF_FORMAT_STRING(const char *fmt), ...)
  PRINTF_ARGS(2, 3);

// Append VARIABLE=VALUE\0 string to the buffer, and add a respective
// pointer into the vars array.
static char *addenv(struct cgi_env_block *block, const char *fmt, ...) {
  int n, space;
  char *added;
  va_list ap;

  // Calculate how much space is left in the buffer
  space = sizeof(block->buf) - block->len - 2;
  assert(space >= 0);

  // Make a pointer to the free space int the buffer
  added = block->buf + block->len;

  // Copy VARIABLE=VALUE\0 string into the free space
  va_start(ap, fmt);
  n = mg_vsnprintf(block->conn, added, (size_t) space, fmt, ap);
  va_end(ap);

  // Make sure we do not overflow buffer and the envp array
  if (n > 0 && n + 1 < space &&
      block->nvars < (int) ARRAY_SIZE(block->vars) - 2) {
    // Append a pointer to the added string into the envp array
    block->vars[block->nvars++] = added;
    // Bump up used length counter. Include \0 terminator
    block->len += n + 1;
  } else {
    cry(block->conn, "%s: CGI env buffer truncated for [%s]", __func__, fmt);
  }

  return added;
}

static void prepare_cgi_environment(struct mg_connection *conn,
                                    const char *prog,
                                    struct cgi_env_block *blk) {
  const char *s, *slash;
  struct vec var_vec;
  char *p, src_addr[IP_ADDR_STR_LEN];
  int  i;

  blk->len = blk->nvars = 0;
  blk->conn = conn;
  sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);

  addenv(blk, "SERVER_NAME=%s", conn->ctx->config[AUTHENTICATION_DOMAIN]);
  addenv(blk, "SERVER_ROOT=%s", conn->ctx->config[DOCUMENT_ROOT]);
  addenv(blk, "DOCUMENT_ROOT=%s", conn->ctx->config[DOCUMENT_ROOT]);

  // Prepare the environment block
  addenv(blk, "%s", "GATEWAY_INTERFACE=CGI/1.1");
  addenv(blk, "%s", "SERVER_PROTOCOL=HTTP/1.1");
  addenv(blk, "%s", "REDIRECT_STATUS=200"); // For PHP

  // TODO(lsm): fix this for IPv6 case
  addenv(blk, "SERVER_PORT=%d", ntohs(conn->client.lsa.sin.sin_port));

  addenv(blk, "REQUEST_METHOD=%s", conn->request_info.request_method);
  addenv(blk, "REMOTE_ADDR=%s", src_addr);
  addenv(blk, "REMOTE_PORT=%d", conn->request_info.remote_port);
  addenv(blk, "REQUEST_URI=%s", conn->request_info.uri);

  // SCRIPT_NAME
  assert(conn->request_info.uri[0] == '/');
  slash = strrchr(conn->request_info.uri, '/');
  if ((s = strrchr(prog, '/')) == NULL)
    s = prog;
  addenv(blk, "SCRIPT_NAME=%.*s%s", (int) (slash - conn->request_info.uri),
         conn->request_info.uri, s);

  addenv(blk, "SCRIPT_FILENAME=%s", prog);
  addenv(blk, "PATH_TRANSLATED=%s", prog);
  addenv(blk, "HTTPS=%s", conn->ssl == NULL ? "off" : "on");

  if ((s = mg_get_header(conn, "Content-Type")) != NULL)
    addenv(blk, "CONTENT_TYPE=%s", s);

  if (conn->request_info.query_string != NULL)
    addenv(blk, "QUERY_STRING=%s", conn->request_info.query_string);

  if ((s = mg_get_header(conn, "Content-Length")) != NULL)
    addenv(blk, "CONTENT_LENGTH=%s", s);

  if ((s = getenv("PATH")) != NULL)
    addenv(blk, "PATH=%s", s);

  if (conn->path_info != NULL) {
    addenv(blk, "PATH_INFO=%s", conn->path_info);
  }

#if defined(_WIN32)
  if ((s = getenv("COMSPEC")) != NULL) {
    addenv(blk, "COMSPEC=%s", s);
  }
  if ((s = getenv("SYSTEMROOT")) != NULL) {
    addenv(blk, "SYSTEMROOT=%s", s);
  }
  if ((s = getenv("SystemDrive")) != NULL) {
    addenv(blk, "SystemDrive=%s", s);
  }
  if ((s = getenv("ProgramFiles")) != NULL) {
    addenv(blk, "ProgramFiles=%s", s);
  }
  if ((s = getenv("ProgramFiles(x86)")) != NULL) {
    addenv(blk, "ProgramFiles(x86)=%s", s);
  }
#else
  if ((s = getenv("LD_LIBRARY_PATH")) != NULL)
    addenv(blk, "LD_LIBRARY_PATH=%s", s);
#endif // _WIN32

  if ((s = getenv("PERLLIB")) != NULL)
    addenv(blk, "PERLLIB=%s", s);

  if (conn->request_info.remote_user != NULL) {
    addenv(blk, "REMOTE_USER=%s", conn->request_info.remote_user);
    addenv(blk, "%s", "AUTH_TYPE=Digest");
  }

  // Add all headers as HTTP_* variables
  for (i = 0; i < conn->request_info.num_headers; i++) {
    p = addenv(blk, "HTTP_%s=%s",
        conn->request_info.http_headers[i].name,
        conn->request_info.http_headers[i].value);

    // Convert variable name into uppercase, and change - to _
    for (; *p != '=' && *p != '\0'; p++) {
      if (*p == '-')
        *p = '_';
      *p = (char) toupper(* (unsigned char *) p);
    }
  }

  // Add user-specified variables
  s = conn->ctx->config[CGI_ENVIRONMENT];
  while ((s = next_option(s, &var_vec, NULL)) != NULL) {
    addenv(blk, "%.*s", (int) var_vec.len, var_vec.ptr);
  }

  blk->vars[blk->nvars++] = NULL;
  blk->buf[blk->len++] = '\0';

  assert(blk->nvars < (int) ARRAY_SIZE(blk->vars));
  assert(blk->len > 0);
  assert(blk->len < (int) sizeof(blk->buf));
}

static void handle_cgi_request(struct mg_connection *conn, const char *prog) {
  int headers_len, data_len, i, fdin[2], fdout[2];
  const char *status, *status_text;
  char buf[16384], *pbuf, dir[PATH_MAX], *p;
  struct mg_request_info ri;
  struct cgi_env_block blk;
  FILE *in = NULL, *out = NULL;
  struct file fout = STRUCT_FILE_INITIALIZER;
  pid_t pid = (pid_t) -1;

  prepare_cgi_environment(conn, prog, &blk);

  // CGI must be executed in its own directory. 'dir' must point to the
  // directory containing executable program, 'p' must point to the
  // executable program name relative to 'dir'.
  (void) mg_snprintf(conn, dir, sizeof(dir), "%s", prog);
  if ((p = strrchr(dir, '/')) != NULL) {
    *p++ = '\0';
  } else {
    dir[0] = '.', dir[1] = '\0';
    p = (char *) prog;
  }

  if (pipe(fdin) != 0 || pipe(fdout) != 0) {
    send_http_error(conn, 500, http_500_error,
        "Cannot create CGI pipe: %s", strerror(ERRNO));
    goto done;
  }

  pid = spawn_process(conn, p, blk.buf, blk.vars, fdin[0], fdout[1], dir);
  if (pid == (pid_t) -1) {
    send_http_error(conn, 500, http_500_error,
        "Cannot spawn CGI process [%s]: %s", prog, strerror(ERRNO));
    goto done;
  }

  // Make sure child closes all pipe descriptors. It must dup them to 0,1
  set_close_on_exec(fdin[0]);
  set_close_on_exec(fdin[1]);
  set_close_on_exec(fdout[0]);
  set_close_on_exec(fdout[1]);

  // Parent closes only one side of the pipes.
  // If we don't mark them as closed, close() attempt before
  // return from this function throws an exception on Windows.
  // Windows does not like when closed descriptor is closed again.
  (void) close(fdin[0]);
  (void) close(fdout[1]);
  fdin[0] = fdout[1] = -1;


  if ((in = fdopen(fdin[1], "wb")) == NULL ||
      (out = fdopen(fdout[0], "rb")) == NULL) {
    send_http_error(conn, 500, http_500_error,
        "fopen: %s", strerror(ERRNO));
    goto done;
  }

  setbuf(in, NULL);
  setbuf(out, NULL);
  fout.fp = out;

  // Send POST data to the CGI process if needed
  if (!strcmp(conn->request_info.request_method, "POST") &&
      !forward_body_data(conn, in, INVALID_SOCKET, NULL)) {
    goto done;
  }

  // Close so child gets an EOF.
  fclose(in);
  in = NULL;
  fdin[1] = -1;

  // Now read CGI reply into a buffer. We need to set correct
  // status code, thus we need to see all HTTP headers first.
  // Do not send anything back to client, until we buffer in all
  // HTTP headers.
  data_len = 0;
  headers_len = read_request(out, conn, buf, sizeof(buf), &data_len);
  if (headers_len <= 0) {
    send_http_error(conn, 500, http_500_error,
                    "CGI program sent malformed or too big (>%u bytes) "
                    "HTTP headers: [%.*s]",
                    (unsigned) sizeof(buf), data_len, buf);
    goto done;
  }
  pbuf = buf;
  buf[headers_len - 1] = '\0';
  parse_http_headers(&pbuf, &ri);

  // Make up and send the status line
  status_text = "OK";
  if ((status = get_header(&ri, "Status")) != NULL) {
    conn->status_code = atoi(status);
    status_text = status;
    while (isdigit(* (unsigned char *) status_text) || *status_text == ' ') {
      status_text++;
    }
  } else if (get_header(&ri, "Location") != NULL) {
    conn->status_code = 302;
  } else {
    conn->status_code = 200;
  }
  if (get_header(&ri, "Connection") != NULL &&
      !mg_strcasecmp(get_header(&ri, "Connection"), "keep-alive")) {
    conn->must_close = 1;
  }
  (void) mg_printf(conn, "HTTP/1.1 %d %s\r\n", conn->status_code,
                   status_text);

  // Send headers
  for (i = 0; i < ri.num_headers; i++) {
    mg_printf(conn, "%s: %s\r\n",
              ri.http_headers[i].name, ri.http_headers[i].value);
  }
  mg_write(conn, "\r\n", 2);

  // Send chunk of data that may have been read after the headers
  conn->num_bytes_sent += mg_write(conn, buf + headers_len,
                                   (size_t)(data_len - headers_len));

  // Read the rest of CGI output and send to the client
  send_file_data(conn, &fout, 0, INT64_MAX);

done:
  if (pid != (pid_t) -1) {
    kill(pid, SIGKILL);
  }
  if (fdin[0] != -1) {
    close(fdin[0]);
  }
  if (fdout[1] != -1) {
    close(fdout[1]);
  }

  if (in != NULL) {
    fclose(in);
  } else if (fdin[1] != -1) {
    close(fdin[1]);
  }

  if (out != NULL) {
    fclose(out);
  } else if (fdout[0] != -1) {
    close(fdout[0]);
  }
}
#endif // !NO_CGI

// For a given PUT path, create all intermediate subdirectories
// for given path. Return 0 if the path itself is a directory,
// or -1 on error, 1 if OK.
static int put_dir(struct mg_connection *conn, const char *path) {
  char buf[PATH_MAX];
  const char *s, *p;
  struct file file = STRUCT_FILE_INITIALIZER;
  int len, res = 1;

  for (s = p = path + 2; (p = strchr(s, '/')) != NULL; s = ++p) {
    len = p - path;
    if (len >= (int) sizeof(buf)) {
      res = -1;
      break;
    }
    memcpy(buf, path, len);
    buf[len] = '\0';

    // Try to create intermediate directory
    DEBUG_TRACE(("mkdir(%s)", buf));
    if (!mg_stat(conn, buf, &file) && mg_mkdir(buf, 0755) != 0) {
      res = -1;
      break;
    }

    // Is path itself a directory?
    if (p[1] == '\0') {
      res = 0;
    }
  }

  return res;
}

static void mkcol(struct mg_connection *conn, const char *path) {
  int rc, body_len;
  struct de de;
  memset(&de.file, 0, sizeof(de.file));
  mg_stat(conn, path, &de.file);

  if(de.file.modification_time) {
      send_http_error(conn, 405, "Method Not Allowed",
                      "mkcol(%s): %s", path, strerror(ERRNO));
      return;
  }

  body_len = conn->data_len - conn->request_len;
  if(body_len > 0) {
      send_http_error(conn, 415, "Unsupported media type",
                      "mkcol(%s): %s", path, strerror(ERRNO));
      return;
  }

  rc = mg_mkdir(path, 0755);

  if (rc == 0) {
    conn->status_code = 201;
    mg_printf(conn, "HTTP/1.1 %d Created\r\n\r\n", conn->status_code);
  } else if (rc == -1) {
      if(errno == EEXIST)
        send_http_error(conn, 405, "Method Not Allowed",
                      "mkcol(%s): %s", path, strerror(ERRNO));
      else if(errno == EACCES)
          send_http_error(conn, 403, "Forbidden",
                        "mkcol(%s): %s", path, strerror(ERRNO));
      else if(errno == ENOENT)
          send_http_error(conn, 409, "Conflict",
                        "mkcol(%s): %s", path, strerror(ERRNO));
      else
          send_http_error(conn, 500, http_500_error,
                          "fopen(%s): %s", path, strerror(ERRNO));
  }
}

static void put_file(struct mg_connection *conn, const char *path) {
  struct file file = STRUCT_FILE_INITIALIZER;
  const char *range;
  int64_t r1, r2;
  int rc;

  conn->status_code = mg_stat(conn, path, &file) ? 200 : 201;

  if ((rc = put_dir(conn, path)) == 0) {
    mg_printf(conn, "HTTP/1.1 %d OK\r\n\r\n", conn->status_code);
  } else if (rc == -1) {
    send_http_error(conn, 500, http_500_error,
                    "put_dir(%s): %s", path, strerror(ERRNO));
  } else if (!mg_fopen(conn, path, "wb+", &file) || file.fp == NULL) {
    mg_fclose(&file);
    send_http_error(conn, 500, http_500_error,
                    "fopen(%s): %s", path, strerror(ERRNO));
  } else {
    fclose_on_exec(&file);
    range = mg_get_header(conn, "Content-Range");
    r1 = r2 = 0;
    if (range != NULL && parse_range_header(range, &r1, &r2) > 0) {
      conn->status_code = 206;
      fseeko(file.fp, r1, SEEK_SET);
    }
    if (forward_body_data(conn, file.fp, INVALID_SOCKET, NULL)) {
      mg_printf(conn, "HTTP/1.1 %d OK\r\n\r\n", conn->status_code);
    }
    mg_fclose(&file);
  }
}

static void send_ssi_file(struct mg_connection *, const char *,
                          struct file *, int);

static void do_ssi_include(struct mg_connection *conn, const char *ssi,
                           char *tag, int include_level) {
  char file_name[MG_BUF_LEN], path[PATH_MAX], *p;
  struct file file = STRUCT_FILE_INITIALIZER;

  // sscanf() is safe here, since send_ssi_file() also uses buffer
  // of size MG_BUF_LEN to get the tag. So strlen(tag) is always < MG_BUF_LEN.
  if (sscanf(tag, " virtual=\"%[^\"]\"", file_name) == 1) {
    // File name is relative to the webserver root
    (void) mg_snprintf(conn, path, sizeof(path), "%s%c%s",
        conn->ctx->config[DOCUMENT_ROOT], '/', file_name);
  } else if (sscanf(tag, " abspath=\"%[^\"]\"", file_name) == 1) {
    // File name is relative to the webserver working directory
    // or it is absolute system path
    (void) mg_snprintf(conn, path, sizeof(path), "%s", file_name);
  } else if (sscanf(tag, " file=\"%[^\"]\"", file_name) == 1 ||
             sscanf(tag, " \"%[^\"]\"", file_name) == 1) {
    // File name is relative to the currect document
    (void) mg_snprintf(conn, path, sizeof(path), "%s", ssi);
    if ((p = strrchr(path, '/')) != NULL) {
      p[1] = '\0';
    }
    (void) mg_snprintf(conn, path + strlen(path),
        sizeof(path) - strlen(path), "%s", file_name);
  } else {
    cry(conn, "Bad SSI #include: [%s]", tag);
    return;
  }

  if (!mg_fopen(conn, path, "rb", &file)) {
    cry(conn, "Cannot open SSI #include: [%s]: fopen(%s): %s",
        tag, path, strerror(ERRNO));
  } else {
    fclose_on_exec(&file);
    if (match_prefix(conn->ctx->config[SSI_EXTENSIONS],
                     strlen(conn->ctx->config[SSI_EXTENSIONS]), path) > 0) {
      send_ssi_file(conn, path, &file, include_level + 1);
    } else {
      send_file_data(conn, &file, 0, INT64_MAX);
    }
    mg_fclose(&file);
  }
}

#if !defined(NO_POPEN)
static void do_ssi_exec(struct mg_connection *conn, char *tag) {
  char cmd[MG_BUF_LEN];
  struct file file = STRUCT_FILE_INITIALIZER;

  if (sscanf(tag, " \"%[^\"]\"", cmd) != 1) {
    cry(conn, "Bad SSI #exec: [%s]", tag);
  } else if ((file.fp = popen(cmd, "r")) == NULL) {
    cry(conn, "Cannot SSI #exec: [%s]: %s", cmd, strerror(ERRNO));
  } else {
    send_file_data(conn, &file, 0, INT64_MAX);
    pclose(file.fp);
  }
}
#endif // !NO_POPEN

static int mg_fgetc(struct file *filep, int offset) {
  if (filep->membuf != NULL && offset >=0 && offset < filep->size) {
    return ((unsigned char *) filep->membuf)[offset];
  } else if (filep->fp != NULL) {
    return fgetc(filep->fp);
  } else {
    return EOF;
  }
}

static void send_ssi_file(struct mg_connection *conn, const char *path,
                          struct file *filep, int include_level) {
  char buf[MG_BUF_LEN];
  int ch, offset, len, in_ssi_tag;

  if (include_level > 10) {
    cry(conn, "SSI #include level is too deep (%s)", path);
    return;
  }

  in_ssi_tag = len = offset = 0;
  while ((ch = mg_fgetc(filep, offset)) != EOF) {
    if (in_ssi_tag && ch == '>') {
      in_ssi_tag = 0;
      buf[len++] = (char) ch;
      buf[len] = '\0';
      assert(len <= (int) sizeof(buf));
      if (len < 6 || memcmp(buf, "<!--#", 5) != 0) {
        // Not an SSI tag, pass it
        (void) mg_write(conn, buf, (size_t) len);
      } else {
        if (!memcmp(buf + 5, "include", 7)) {
          do_ssi_include(conn, path, buf + 12, include_level);
#if !defined(NO_POPEN)
        } else if (!memcmp(buf + 5, "exec", 4)) {
          do_ssi_exec(conn, buf + 9);
#endif // !NO_POPEN
        } else {
          cry(conn, "%s: unknown SSI " "command: \"%s\"", path, buf);
        }
      }
      len = 0;
    } else if (in_ssi_tag) {
      if (len == 5 && memcmp(buf, "<!--#", 5) != 0) {
        // Not an SSI tag
        in_ssi_tag = 0;
      } else if (len == (int) sizeof(buf) - 2) {
        cry(conn, "%s: SSI tag is too large", path);
        len = 0;
      }
      buf[len++] = ch & 0xff;
    } else if (ch == '<') {
      in_ssi_tag = 1;
      if (len > 0) {
        mg_write(conn, buf, (size_t) len);
      }
      len = 0;
      buf[len++] = ch & 0xff;
    } else {
      buf[len++] = ch & 0xff;
      if (len == (int) sizeof(buf)) {
        mg_write(conn, buf, (size_t) len);
        len = 0;
      }
    }
  }

  // Send the rest of buffered data
  if (len > 0) {
    mg_write(conn, buf, (size_t) len);
  }
}

static void handle_ssi_file_request(struct mg_connection *conn,
                                    const char *path) {
  struct file file = STRUCT_FILE_INITIALIZER;

  if (!mg_fopen(conn, path, "rb", &file)) {
    send_http_error(conn, 500, http_500_error, "fopen(%s): %s", path,
                    strerror(ERRNO));
  } else {
    conn->must_close = 1;
    fclose_on_exec(&file);
    mg_printf(conn, "HTTP/1.1 200 OK\r\n"
              "Content-Type: text/html\r\nConnection: %s\r\n\r\n",
              suggest_connection_header(conn));
    send_ssi_file(conn, path, &file, 0);
    mg_fclose(&file);
  }
}

static void send_options(struct mg_connection *conn) {
  conn->status_code = 200;

  mg_printf(conn, "%s", "HTTP/1.1 200 OK\r\n"
            "Allow: GET, POST, HEAD, CONNECT, PUT, DELETE, OPTIONS, PROPFIND, MKCOL\r\n"
            "DAV: 1\r\n\r\n");
}

// Writes PROPFIND properties for a collection element
static void print_props(struct mg_connection *conn, const char* uri,
                        struct file *filep) {
  char mtime[64];
  gmt_time_string(mtime, sizeof(mtime), &filep->modification_time);
  conn->num_bytes_sent += mg_printf(conn,
      "<d:response>"
       "<d:href>%s</d:href>"
       "<d:propstat>"
        "<d:prop>"
         "<d:resourcetype>%s</d:resourcetype>"
         "<d:getcontentlength>%" INT64_FMT "</d:getcontentlength>"
         "<d:getlastmodified>%s</d:getlastmodified>"
        "</d:prop>"
        "<d:status>HTTP/1.1 200 OK</d:status>"
       "</d:propstat>"
      "</d:response>\n",
      uri,
      filep->is_directory ? "<d:collection/>" : "",
      filep->size,
      mtime);
}

static void print_dav_dir_entry(struct de *de, void *data) {
  char href[PATH_MAX];
  char href_encoded[PATH_MAX];
  struct mg_connection *conn = (struct mg_connection *) data;
  mg_snprintf(conn, href, sizeof(href), "%s%s",
              conn->request_info.uri, de->file_name);
  mg_url_encode(href, href_encoded, PATH_MAX-1);
  print_props(conn, href_encoded, &de->file);
}

static void handle_propfind(struct mg_connection *conn, const char *path,
                            struct file *filep) {
  const char *depth = mg_get_header(conn, "Depth");

  conn->must_close = 1;
  conn->status_code = 207;
  mg_printf(conn, "HTTP/1.1 207 Multi-Status\r\n"
            "Connection: close\r\n"
            "Content-Type: text/xml; charset=utf-8\r\n\r\n");

  conn->num_bytes_sent += mg_printf(conn,
      "<?xml version=\"1.0\" encoding=\"utf-8\"?>"
      "<d:multistatus xmlns:d='DAV:'>\n");

  // Print properties for the requested resource itself
  print_props(conn, conn->request_info.uri, filep);

  // If it is a directory, print directory entries too if Depth is not 0
  if (filep->is_directory &&
      !mg_strcasecmp(conn->ctx->config[ENABLE_DIRECTORY_LISTING], "yes") &&
      (depth == NULL || strcmp(depth, "0") != 0)) {
    scan_directory(conn, path, conn, &print_dav_dir_entry);
  }

  conn->num_bytes_sent += mg_printf(conn, "%s\n", "</d:multistatus>");
}

#if defined(USE_WEBSOCKET)

// START OF SHA-1 code
// Copyright(c) By Steve Reid <steve@edmweb.com>
#define SHA1HANDSOFF
#if defined(__sun)
#include "solarisfixes.h"
#endif

union char64long16 { unsigned char c[64]; uint32_t l[16]; };

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

static uint32_t blk0(union char64long16 *block, int i) {
  // Forrest: SHA expect BIG_ENDIAN, swap if LITTLE_ENDIAN
  if (!is_big_endian()) {
    block->l[i] = (rol(block->l[i], 24) & 0xFF00FF00) |
      (rol(block->l[i], 8) & 0x00FF00FF);
  }
  return block->l[i];
}

#define blk(i) (block->l[i&15] = rol(block->l[(i+13)&15]^block->l[(i+8)&15] \
    ^block->l[(i+2)&15]^block->l[i&15],1))
#define R0(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk0(block, i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R1(v,w,x,y,z,i) z+=((w&(x^y))^y)+blk(i)+0x5A827999+rol(v,5);w=rol(w,30);
#define R2(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0x6ED9EBA1+rol(v,5);w=rol(w,30);
#define R3(v,w,x,y,z,i) z+=(((w|x)&y)|(w&x))+blk(i)+0x8F1BBCDC+rol(v,5);w=rol(w,30);
#define R4(v,w,x,y,z,i) z+=(w^x^y)+blk(i)+0xCA62C1D6+rol(v,5);w=rol(w,30);

typedef struct {
    uint32_t state[5];
    uint32_t count[2];
    unsigned char buffer[64];
} SHA1_CTX;

static void SHA1Transform(uint32_t state[5], const unsigned char buffer[64]) {
  uint32_t a, b, c, d, e;
  union char64long16 block[1];

  memcpy(block, buffer, 64);
  a = state[0];
  b = state[1];
  c = state[2];
  d = state[3];
  e = state[4];
  R0(a,b,c,d,e, 0); R0(e,a,b,c,d, 1); R0(d,e,a,b,c, 2); R0(c,d,e,a,b, 3);
  R0(b,c,d,e,a, 4); R0(a,b,c,d,e, 5); R0(e,a,b,c,d, 6); R0(d,e,a,b,c, 7);
  R0(c,d,e,a,b, 8); R0(b,c,d,e,a, 9); R0(a,b,c,d,e,10); R0(e,a,b,c,d,11);
  R0(d,e,a,b,c,12); R0(c,d,e,a,b,13); R0(b,c,d,e,a,14); R0(a,b,c,d,e,15);
  R1(e,a,b,c,d,16); R1(d,e,a,b,c,17); R1(c,d,e,a,b,18); R1(b,c,d,e,a,19);
  R2(a,b,c,d,e,20); R2(e,a,b,c,d,21); R2(d,e,a,b,c,22); R2(c,d,e,a,b,23);
  R2(b,c,d,e,a,24); R2(a,b,c,d,e,25); R2(e,a,b,c,d,26); R2(d,e,a,b,c,27);
  R2(c,d,e,a,b,28); R2(b,c,d,e,a,29); R2(a,b,c,d,e,30); R2(e,a,b,c,d,31);
  R2(d,e,a,b,c,32); R2(c,d,e,a,b,33); R2(b,c,d,e,a,34); R2(a,b,c,d,e,35);
  R2(e,a,b,c,d,36); R2(d,e,a,b,c,37); R2(c,d,e,a,b,38); R2(b,c,d,e,a,39);
  R3(a,b,c,d,e,40); R3(e,a,b,c,d,41); R3(d,e,a,b,c,42); R3(c,d,e,a,b,43);
  R3(b,c,d,e,a,44); R3(a,b,c,d,e,45); R3(e,a,b,c,d,46); R3(d,e,a,b,c,47);
  R3(c,d,e,a,b,48); R3(b,c,d,e,a,49); R3(a,b,c,d,e,50); R3(e,a,b,c,d,51);
  R3(d,e,a,b,c,52); R3(c,d,e,a,b,53); R3(b,c,d,e,a,54); R3(a,b,c,d,e,55);
  R3(e,a,b,c,d,56); R3(d,e,a,b,c,57); R3(c,d,e,a,b,58); R3(b,c,d,e,a,59);
  R4(a,b,c,d,e,60); R4(e,a,b,c,d,61); R4(d,e,a,b,c,62); R4(c,d,e,a,b,63);
  R4(b,c,d,e,a,64); R4(a,b,c,d,e,65); R4(e,a,b,c,d,66); R4(d,e,a,b,c,67);
  R4(c,d,e,a,b,68); R4(b,c,d,e,a,69); R4(a,b,c,d,e,70); R4(e,a,b,c,d,71);
  R4(d,e,a,b,c,72); R4(c,d,e,a,b,73); R4(b,c,d,e,a,74); R4(a,b,c,d,e,75);
  R4(e,a,b,c,d,76); R4(d,e,a,b,c,77); R4(c,d,e,a,b,78); R4(b,c,d,e,a,79);
  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;
  state[4] += e;
  a = b = c = d = e = 0;
  memset(block, '\0', sizeof(block));
}

static void SHA1Init(SHA1_CTX* context) {
  context->state[0] = 0x67452301;
  context->state[1] = 0xEFCDAB89;
  context->state[2] = 0x98BADCFE;
  context->state[3] = 0x10325476;
  context->state[4] = 0xC3D2E1F0;
  context->count[0] = context->count[1] = 0;
}

static void SHA1Update(SHA1_CTX* context, const unsigned char* data,
                       uint32_t len) {
  uint32_t i, j;

  j = context->count[0];
  if ((context->count[0] += len << 3) < j)
    context->count[1]++;
  context->count[1] += (len>>29);
  j = (j >> 3) & 63;
  if ((j + len) > 63) {
    memcpy(&context->buffer[j], data, (i = 64-j));
    SHA1Transform(context->state, context->buffer);
    for ( ; i + 63 < len; i += 64) {
      SHA1Transform(context->state, &data[i]);
    }
    j = 0;
  }
  else i = 0;
  memcpy(&context->buffer[j], &data[i], len - i);
}

static void SHA1Final(unsigned char digest[20], SHA1_CTX* context) {
  unsigned i;
  unsigned char finalcount[8], c;

  for (i = 0; i < 8; i++) {
    finalcount[i] = (unsigned char)((context->count[(i >= 4 ? 0 : 1)]
                                     >> ((3-(i & 3)) * 8) ) & 255);
  }
  c = 0200;
  SHA1Update(context, &c, 1);
  while ((context->count[0] & 504) != 448) {
    c = 0000;
    SHA1Update(context, &c, 1);
  }
  SHA1Update(context, finalcount, 8);
  for (i = 0; i < 20; i++) {
    digest[i] = (unsigned char)
      ((context->state[i>>2] >> ((3-(i & 3)) * 8) ) & 255);
  }
  memset(context, '\0', sizeof(*context));
  memset(&finalcount, '\0', sizeof(finalcount));
}
// END OF SHA1 CODE

static void base64_encode(const unsigned char *src, int src_len, char *dst) {
  static const char *b64 =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  int i, j, a, b, c;

  for (i = j = 0; i < src_len; i += 3) {
    a = src[i];
    b = i + 1 >= src_len ? 0 : src[i + 1];
    c = i + 2 >= src_len ? 0 : src[i + 2];

    dst[j++] = b64[a >> 2];
    dst[j++] = b64[((a & 3) << 4) | (b >> 4)];
    if (i + 1 < src_len) {
      dst[j++] = b64[(b & 15) << 2 | (c >> 6)];
    }
    if (i + 2 < src_len) {
      dst[j++] = b64[c & 63];
    }
  }
  while (j % 4 != 0) {
    dst[j++] = '=';