mongoose.c

    //     v                     v              frame1           | frame2
    //     |---------------------|----------------|--------------|-------
    //     |                     |<--header_len-->|<--data_len-->|
    //     |<-conn->request_len->|<-----body_len----------->|
    //     |<-------------------conn->data_len------------->|

    if (header_len > 0) {
      // Allocate space to hold websocket payload
      if ((*data = malloc(data_len)) == NULL) {
        // Allocation failed, exit the loop and then close the connection
        // TODO: notify user about the failure
        data_len = 0;
        break;
      }

      // Save mask and bits, otherwise it may be clobbered by memmove below
      *bits = buf[0];
      memcpy(mask, buf + header_len - mask_len, mask_len);

      // Read frame payload into the allocated buffer.
      assert(body_len >= header_len);
      if (data_len + header_len > body_len) {
        len = body_len - header_len;
        memcpy(*data, buf + header_len, len);
        // TODO: handle pull error
        pull_all(NULL, conn, *data + len, data_len - len);
        conn->data_len = conn->request_len;
      } else {
        len = data_len + header_len;
        memcpy(*data, buf + header_len, data_len);
        memmove(buf, buf + len, body_len - len);
        conn->data_len -= len;
      }

      // Apply mask if necessary
      if (mask_len > 0) {
        for (i = 0; i < data_len; i++) {
          (*data)[i] ^= mask[i % 4];
        }
      }

      return data_len;
    } else {
      // Buffering websocket request
      if ((n = pull(NULL, conn, conn->buf + conn->data_len,
                    conn->buf_size - conn->data_len)) <= 0) {
        break;
      }
      conn->data_len += n;
    }
  }

  return 0;
}

int mg_websocket_write(struct mg_connection* conn, int opcode,
                       const char *data, size_t data_len) {
    unsigned char *copy;
    size_t copy_len = 0;
    int retval = -1;

    if ((copy = (unsigned char *) malloc(data_len + 10)) == NULL) {
      return -1;
    }

    copy[0] = 0x80 + (opcode & 0x0f);

    // Frame format: http://tools.ietf.org/html/rfc6455#section-5.2
    if (data_len < 126) {
      // Inline 7-bit length field
      copy[1] = data_len;
      memcpy(copy + 2, data, data_len);
      copy_len = 2 + data_len;
    } else if (data_len <= 0xFFFF) {
      // 16-bit length field
      copy[1] = 126;
      * (uint16_t *) (copy + 2) = htons(data_len);
      memcpy(copy + 4, data, data_len);
      copy_len = 4 + data_len;
    } else {
      // 64-bit length field
      copy[1] = 127;
      * (uint32_t *) (copy + 2) = htonl((uint64_t) data_len >> 32);
      * (uint32_t *) (copy + 6) = htonl(data_len & 0xffffffff);
      memcpy(copy + 10, data, data_len);
      copy_len = 10 + data_len;
    }

    // Not thread safe
    if (copy_len > 0) {
      retval = mg_write(conn, copy, copy_len);
    }
    free(copy);

    return retval;
}
#endif // !USE_WEBSOCKET

static int isbyte(int n) {
  return n >= 0 && n <= 255;
}

static int parse_net(const char *spec, uint32_t *net, uint32_t *mask) {
  int n, a, b, c, d, slash = 32, len = 0;

  if ((sscanf(spec, "%d.%d.%d.%d/%d%n", &a, &b, &c, &d, &slash, &n) == 5 ||
      sscanf(spec, "%d.%d.%d.%d%n", &a, &b, &c, &d, &n) == 4) &&
      isbyte(a) && isbyte(b) && isbyte(c) && isbyte(d) &&
      slash >= 0 && slash < 33) {
    len = n;
    *net = ((uint32_t)a << 24) | ((uint32_t)b << 16) | ((uint32_t)c << 8) | d;
    *mask = slash ? 0xffffffffU << (32 - slash) : 0;
  }

  return len;
}

static int set_throttle(const char *spec, uint32_t remote_ip, const char *uri) {
  int throttle = 0;
  struct vec vec, val;
  uint32_t net, mask;
  char mult;
  double v;

  while ((spec = next_option(spec, &vec, &val)) != NULL) {
    mult = ',';
    if (sscanf(val.ptr, "%lf%c", &v, &mult) < 1 || v < 0 ||
        (lowercase(&mult) != 'k' && lowercase(&mult) != 'm' && mult != ',')) {
      continue;
    }
    v *= lowercase(&mult) == 'k' ? 1024 : lowercase(&mult) == 'm' ? 1048576 : 1;
    if (vec.len == 1 && vec.ptr[0] == '*') {
      throttle = (int) v;
    } else if (parse_net(vec.ptr, &net, &mask) > 0) {
      if ((remote_ip & mask) == net) {
        throttle = (int) v;
      }
    } else if (match_prefix(vec.ptr, vec.len, uri) > 0) {
      throttle = (int) v;
    }
  }

  return throttle;
}

static uint32_t get_remote_ip(const struct mg_connection *conn) {
  return ntohl(* (uint32_t *) &conn->client.rsa.sin.sin_addr);
}

#ifdef USE_LUA
#include "build/mod_lua.c"
#endif // USE_LUA

FILE *mg_upload(struct mg_connection *conn, const char *destination_dir,
                char *path, int path_len) {
  const char *content_type_header, *boundary_start;
  char *buf, fname[1024], boundary[100], *s;
  int bl, n, i, j, headers_len, boundary_len, eof, buf_len, to_read, len = 0;
  FILE *fp;

  // Request looks like this:
  //
  // POST /upload HTTP/1.1
  // Host: 127.0.0.1:8080
  // Content-Length: 244894
  // Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryRVr
  //
  // ------WebKitFormBoundaryRVr
  // Content-Disposition: form-data; name="file"; filename="accum.png"
  // Content-Type: image/png
  //
  //  <89>PNG
  //  <PNG DATA>
  // ------WebKitFormBoundaryRVr

  // Extract boundary string from the Content-Type header
  if ((content_type_header = mg_get_header(conn, "Content-Type")) == NULL ||
      (boundary_start = mg_strcasestr(content_type_header,
                                      "boundary=")) == NULL ||
      (sscanf(boundary_start, "boundary=\"%99[^\"]\"", boundary) == 0 &&
       sscanf(boundary_start, "boundary=%99s", boundary) == 0) ||
      boundary[0] == '\0') {
    return NULL;
  }

  boundary_len = strlen(boundary);
  bl = boundary_len + 4;  // \r\n--<boundary>

  //                     buf
  // conn->buf            |<--------- buf_len ------>|
  //    |=================|==========|===============|
  //    |<--request_len-->|<--len--->|               |
  //    |<-----------data_len------->|      conn->buf + conn->buf_size

  buf = conn->buf + conn->request_len;
  buf_len = conn->buf_size - conn->request_len;
  len = conn->data_len - conn->request_len;

  for (;;) {
    // Pull in headers
    assert(len >= 0 && len <= buf_len);
    to_read = buf_len - len;
    if (to_read > left_to_read(conn)) {
      to_read = (int) left_to_read(conn);
    }
    while (len < buf_len &&
           (n = pull(NULL, conn, buf + len, to_read)) > 0) {
      len += n;
    }
    if ((headers_len = get_request_len(buf, len)) <= 0) {
      break;
    }

    // Fetch file name.
    fname[0] = '\0';
    for (i = j = 0; i < headers_len; i++) {
      if (buf[i] == '\r' && buf[i + 1] == '\n') {
        buf[i] = buf[i + 1] = '\0';
        // TODO(lsm): don't expect filename to be the 3rd field,
        // parse the header properly instead.
        sscanf(&buf[j], "Content-Disposition: %*s %*s filename=\"%1023[^\"]",
               fname);
        j = i + 2;
      }
    }

    // Give up if the headers are not what we expect
    if (fname[0] == '\0') {
      break;
    }

    // Move data to the beginning of the buffer
    assert(len >= headers_len);
    memmove(buf, &buf[headers_len], len - headers_len);
    len -= headers_len;
    conn->data_len = conn->request_len + len;

    // We open the file with exclusive lock held. This guarantee us
    // there is no other thread can save into the same file simultaneously.
    fp = NULL;

    // Construct destination file name. Do not allow paths to have slashes.
    if ((s = strrchr(fname, '/')) == NULL &&
        (s = strrchr(fname, '\\')) == NULL) {
      s = fname;
    }

    // Open file in binary mode. TODO: set an exclusive lock.
    snprintf(path, path_len, "%s/%s", destination_dir, s);
    if ((fp = fopen(path, "wb")) == NULL) {
      break;
    }

    // Read POST data, write into file until boundary is found.
    eof = n = 0;
    do {
      len += n;
      for (i = 0; i < len - bl; i++) {
        if (!memcmp(&buf[i], "\r\n--", 4) &&
            !memcmp(&buf[i + 4], boundary, boundary_len)) {
          // Found boundary, that's the end of file data.
          fwrite(buf, 1, i, fp);
          eof = 1;
          memmove(buf, &buf[i + bl], len - (i + bl));
          len -= i + bl;
          break;
        }
      }
      if (!eof && len > bl) {
        fwrite(buf, 1, len - bl, fp);
        memmove(buf, &buf[len - bl], bl);
        len = bl;
      }
      to_read = buf_len - len;
      if (to_read > left_to_read(conn)) {
        to_read = (int) left_to_read(conn);
      }
    } while (!eof && (n = pull(NULL, conn, buf + len, to_read)) > 0);
    conn->data_len = conn->request_len + len;

    if (eof) {
      rewind(fp);
      return fp;
    } else {
      fclose(fp);
    }
  }

  return NULL;
}

static int is_put_or_delete_request(const struct mg_connection *conn) {
  const char *s = conn->request_info.request_method;
  return s != NULL && (!strcmp(s, "PUT") ||
                       !strcmp(s, "DELETE") ||
                       !strcmp(s, "MKCOL"));
}

static int get_first_ssl_listener_index(const struct mg_context *ctx) {
  int i, index = -1;
  for (i = 0; index == -1 && i < ctx->num_listening_sockets; i++) {
    index = ctx->listening_sockets[i].is_ssl ? i : -1;
  }
  return index;
}

static void redirect_to_https_port(struct mg_connection *conn, int ssl_index) {
  char host[1025];
  const char *host_header;

  if ((host_header = mg_get_header(conn, "Host")) == NULL ||
      sscanf(host_header, "%1024[^:]", host) == 0) {
    // Cannot get host from the Host: header. Fallback to our IP address.
    sockaddr_to_string(host, sizeof(host), &conn->client.lsa);
  }

  mg_printf(conn, "HTTP/1.1 302 Found\r\nLocation: https://%s:%d%s\r\n\r\n",
            host, (int) ntohs(conn->ctx->listening_sockets[ssl_index].
                              lsa.sin.sin_port), conn->request_info.uri);
}

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

  if (!mg_stat(path, &file)) {
    send_http_error(conn, 404, "Not Found", "%s", "File not found");
  } else if (!file.modification_time) {
    send_http_error(conn, 500, http_500_error, "remove(%s): %s", path,
                    strerror(ERRNO));
  } else if (file.is_directory) {
    remove_directory(conn, path);
    send_http_error(conn, 204, "No Content", "%s", "");
  } else if (mg_remove(path) == 0) {
    send_http_error(conn, 204, "No Content", "%s", "");
  } else {
    send_http_error(conn, 423, "Locked", "remove(%s): %s", path,
                    strerror(ERRNO));
  }
}

// This is the heart of the Mongoose's logic.
// This function is called when the request is read, parsed and validated,
// and Mongoose must decide what action to take: serve a file, or
// a directory, or call embedded function, etcetera.
static void handle_request(struct mg_connection *conn) {
  struct mg_request_info *ri = &conn->request_info;
  char path[PATH_MAX];
  int uri_len, ssl_index;
  struct file file = STRUCT_FILE_INITIALIZER;

  if ((conn->request_info.query_string = strchr(ri->uri, '?')) != NULL) {
    * ((char *) conn->request_info.query_string++) = '\0';
  }
  uri_len = (int) strlen(ri->uri);
  mg_url_decode(ri->uri, uri_len, (char *) ri->uri, uri_len + 1, 0);
  remove_double_dots_and_double_slashes((char *) ri->uri);
  conn->throttle = set_throttle(conn->ctx->config[THROTTLE],
                                get_remote_ip(conn), ri->uri);
  path[0] = '\0';
  convert_uri_to_file_name(conn, path, sizeof(path), &file);

  // Perform redirect and auth checks before calling begin_request() handler.
  // Otherwise, begin_request() would need to perform auth checks and redirects.
  if (!conn->client.is_ssl && conn->client.ssl_redir &&
      (ssl_index = get_first_ssl_listener_index(conn->ctx)) > -1) {
    redirect_to_https_port(conn, ssl_index);
  } else if (!is_put_or_delete_request(conn) &&
             !check_authorization(conn, path)) {
    send_authorization_request(conn);
  } else if (call_user(MG_REQUEST_BEGIN, conn, (void *) ri->uri) == 1) {
    // Do nothing, callback has served the request
  } else if (!strcmp(ri->request_method, "OPTIONS")) {
    handle_options_request(conn);
  } else if (conn->ctx->config[DOCUMENT_ROOT] == NULL) {
    send_http_error(conn, 404, "Not Found", "Not Found");
  } else if (is_put_or_delete_request(conn) &&
             (is_authorized_for_put(conn) != 1)) {
    send_authorization_request(conn);
  } else if (!strcmp(ri->request_method, "PUT")) {
    put_file(conn, path);
  } else if (!strcmp(ri->request_method, "MKCOL")) {
    mkcol(conn, path);
  } else if (!strcmp(ri->request_method, "DELETE")) {
    handle_delete_request(conn, path);
  } else if (file.modification_time == (time_t) 0 ||
             must_hide_file(conn, path)) {
    send_http_error(conn, 404, "Not Found", "%s", "File not found");
  } else if (file.is_directory && ri->uri[uri_len - 1] != '/') {
    mg_printf(conn, "HTTP/1.1 301 Moved Permanently\r\n"
              "Location: %s/\r\n\r\n", ri->uri);
  } else if (!strcmp(ri->request_method, "PROPFIND")) {
    handle_propfind(conn, path, &file);
  } else if (file.is_directory &&
             !substitute_index_file(conn, path, sizeof(path), &file)) {
    if (!mg_strcasecmp(conn->ctx->config[ENABLE_DIRECTORY_LISTING], "yes")) {
      handle_directory_request(conn, path);
    } else {
      send_http_error(conn, 403, "Directory Listing Denied",
          "Directory listing denied");
    }
#ifdef USE_LUA
  } else if (match_prefix("**.lp$", 6, path) > 0) {
    handle_lsp_request(conn, path, &file, NULL);
#endif
#if !defined(NO_CGI)
  } else if (match_prefix(conn->ctx->config[CGI_EXTENSIONS],
                          strlen(conn->ctx->config[CGI_EXTENSIONS]),
                          path) > 0) {
    if (strcmp(ri->request_method, "POST") &&
        strcmp(ri->request_method, "HEAD") &&
        strcmp(ri->request_method, "GET")) {
      send_http_error(conn, 501, "Not Implemented",
                      "Method %s is not implemented", ri->request_method);
    } else {
      handle_cgi_request(conn, path);
    }
#endif // !NO_CGI
  } else if (match_prefix(conn->ctx->config[SSI_EXTENSIONS],
                          strlen(conn->ctx->config[SSI_EXTENSIONS]),
                          path) > 0) {
    handle_ssi_file_request(conn, path);
  } else if (is_not_modified(conn, &file)) {
    send_http_error(conn, 304, "Not Modified", "%s", "");
  } else {
    handle_file_request(conn, path, &file);
  }
}

static void close_all_listening_sockets(struct mg_context *ctx) {
  int i;
  for (i = 0; i < ctx->num_listening_sockets; i++) {
    closesocket(ctx->listening_sockets[i].sock);
  }
  free(ctx->listening_sockets);
}

static int is_valid_port(unsigned int port) {
  return port > 0 && port < 0xffff;
}

// Valid listening port specification is: [ip_address:]port[s]
// Examples: 80, 443s, 127.0.0.1:3128, 1.2.3.4:8080s
// TODO(lsm): add parsing of the IPv6 address
static int parse_port_string(const struct vec *vec, struct socket *so) {
  unsigned int a, b, c, d, ch, port;
  int len;
#if defined(USE_IPV6)
  char buf[100];
#endif

  // MacOS needs that. If we do not zero it, subsequent bind() will fail.
  // Also, all-zeroes in the socket address means binding to all addresses
  // for both IPv4 and IPv6 (INADDR_ANY and IN6ADDR_ANY_INIT).
  memset(so, 0, sizeof(*so));
  so->lsa.sin.sin_family = AF_INET;

  if (sscanf(vec->ptr, "%u.%u.%u.%u:%u%n", &a, &b, &c, &d, &port, &len) == 5) {
    // Bind to a specific IPv4 address, e.g. 192.168.1.5:8080
    so->lsa.sin.sin_addr.s_addr = htonl((a << 24) | (b << 16) | (c << 8) | d);
    so->lsa.sin.sin_port = htons((uint16_t) port);
#if defined(USE_IPV6)

  } else if (sscanf(vec->ptr, "[%49[^]]]:%d%n", buf, &port, &len) == 2 &&
             inet_pton(AF_INET6, buf, &so->lsa.sin6.sin6_addr)) {
    // IPv6 address, e.g. [3ffe:2a00:100:7031::1]:8080
    so->lsa.sin6.sin6_family = AF_INET6;
    so->lsa.sin6.sin6_port = htons((uint16_t) port);
#endif
  } else if (sscanf(vec->ptr, "%u%n", &port, &len) == 1) {
    // If only port is specified, bind to IPv4, INADDR_ANY
    so->lsa.sin.sin_port = htons((uint16_t) port);
  } else {
    port = len = 0;   // Parsing failure. Make port invalid.
  }

  ch = vec->ptr[len];  // Next character after the port number
  so->is_ssl = ch == 's';
  so->ssl_redir = ch == 'r';

  // Make sure the port is valid and vector ends with 's', 'r' or ','
  return is_valid_port(port) &&
    (ch == '\0' || ch == 's' || ch == 'r' || ch == ',');
}

static int set_ports_option(struct mg_context *ctx) {
  const char *list = ctx->config[LISTENING_PORTS];
  int on = 1, success = 1;
#if defined(USE_IPV6)
  int off = 0;
#endif
  struct vec vec;
  struct socket so, *ptr;

  while (success && (list = next_option(list, &vec, NULL)) != NULL) {
    if (!parse_port_string(&vec, &so)) {
      cry(fc(ctx), "%s: %.*s: invalid port spec. Expecting list of: %s",
          __func__, (int) vec.len, vec.ptr, "[IP_ADDRESS:]PORT[s|r]");
      success = 0;
    } else if (so.is_ssl && ctx->ssl_ctx == NULL) {
      cry(fc(ctx), "Cannot add SSL socket, is -ssl_certificate option set?");
      success = 0;
    } else if ((so.sock = socket(so.lsa.sa.sa_family, SOCK_STREAM, 6)) ==
               INVALID_SOCKET ||
               // On Windows, SO_REUSEADDR is recommended only for
               // broadcast UDP sockets
               setsockopt(so.sock, SOL_SOCKET, SO_REUSEADDR,
                          (void *) &on, sizeof(on)) != 0 ||
#if defined(USE_IPV6)
               (so.lsa.sa.sa_family == AF_INET6 &&
                setsockopt(so.sock, IPPROTO_IPV6, IPV6_V6ONLY, (void *) &off,
                           sizeof(off)) != 0) ||
#endif
               bind(so.sock, &so.lsa.sa, so.lsa.sa.sa_family == AF_INET ?
                    sizeof(so.lsa.sin) : sizeof(so.lsa)) != 0 ||
               listen(so.sock, SOMAXCONN) != 0) {
      cry(fc(ctx), "%s: cannot bind to %.*s: %d (%s)", __func__,
          (int) vec.len, vec.ptr, ERRNO, strerror(errno));
      closesocket(so.sock);
      success = 0;
    } else if ((ptr = (struct socket *) realloc(ctx->listening_sockets,
                              (ctx->num_listening_sockets + 1) *
                              sizeof(ctx->listening_sockets[0]))) == NULL) {
      closesocket(so.sock);
      success = 0;
    } else {
      set_close_on_exec(so.sock);
      ctx->listening_sockets = ptr;
      ctx->listening_sockets[ctx->num_listening_sockets] = so;
      ctx->num_listening_sockets++;
    }
  }

  if (!success) {
    close_all_listening_sockets(ctx);
  }

  return success;
}

static void log_header(const struct mg_connection *conn, const char *header,
                       FILE *fp) {
  const char *header_value;

  if ((header_value = mg_get_header(conn, header)) == NULL) {
    (void) fprintf(fp, "%s", " -");
  } else {
    (void) fprintf(fp, " \"%s\"", header_value);
  }
}

static void log_access(const struct mg_connection *conn) {
  const struct mg_request_info *ri;
  FILE *fp;
  char date[64], src_addr[IP_ADDR_STR_LEN];

  fp = conn->ctx->config[ACCESS_LOG_FILE] == NULL ?  NULL :
    fopen(conn->ctx->config[ACCESS_LOG_FILE], "a+");

  if (fp == NULL)
    return;

  strftime(date, sizeof(date), "%d/%b/%Y:%H:%M:%S %z",
           localtime(&conn->birth_time));

  ri = &conn->request_info;
  flockfile(fp);

  sockaddr_to_string(src_addr, sizeof(src_addr), &conn->client.rsa);
  fprintf(fp, "%s - %s [%s] \"%s %s HTTP/%s\" %d %" INT64_FMT,
          src_addr, ri->remote_user == NULL ? "-" : ri->remote_user, date,
          ri->request_method ? ri->request_method : "-",
          ri->uri ? ri->uri : "-", ri->http_version,
          conn->status_code, conn->num_bytes_sent);
  log_header(conn, "Referer", fp);
  log_header(conn, "User-Agent", fp);
  fputc('\n', fp);
  fflush(fp);

  funlockfile(fp);
  fclose(fp);
}

// Verify given socket address against the ACL.
// Return -1 if ACL is malformed, 0 if address is disallowed, 1 if allowed.
static int check_acl(struct mg_context *ctx, uint32_t remote_ip) {
  int allowed, flag;
  uint32_t net, mask;
  struct vec vec;
  const char *list = ctx->config[ACCESS_CONTROL_LIST];

  // If any ACL is set, deny by default
  allowed = list == NULL ? '+' : '-';

  while ((list = next_option(list, &vec, NULL)) != NULL) {
    flag = vec.ptr[0];
    if ((flag != '+' && flag != '-') ||
        parse_net(&vec.ptr[1], &net, &mask) == 0) {
      cry(fc(ctx), "%s: subnet must be [+|-]x.x.x.x[/x]", __func__);
      return -1;
    }

    if (net == (remote_ip & mask)) {
      allowed = flag;
    }
  }

  return allowed == '+';
}

#if !defined(_WIN32)
static int set_uid_option(struct mg_context *ctx) {
  struct passwd *pw;
  const char *uid = ctx->config[RUN_AS_USER];
  int success = 0;

  if (uid == NULL) {
    success = 1;
  } else {
    if ((pw = getpwnam(uid)) == NULL) {
      cry(fc(ctx), "%s: unknown user [%s]", __func__, uid);
    } else if (setgid(pw->pw_gid) == -1) {
      cry(fc(ctx), "%s: setgid(%s): %s", __func__, uid, strerror(errno));
    } else if (setuid(pw->pw_uid) == -1) {
      cry(fc(ctx), "%s: setuid(%s): %s", __func__, uid, strerror(errno));
    } else {
      success = 1;
    }
  }

  return success;
}
#endif // !_WIN32

#if !defined(NO_SSL)
// set_ssl_option() function updates this array.
// It loads SSL library dynamically and changes NULLs to the actual addresses
// of respective functions. The macros above (like SSL_connect()) are really
// just calling these functions indirectly via the pointer.
static struct ssl_func ssl_sw[] = {
  {"SSL_free",   NULL},
  {"SSL_accept",   NULL},
  {"SSL_connect",   NULL},
  {"SSL_read",   NULL},
  {"SSL_write",   NULL},
  {"SSL_get_error",  NULL},
  {"SSL_set_fd",   NULL},
  {"SSL_new",   NULL},
  {"SSL_CTX_new",   NULL},
  {"SSLv23_server_method", NULL},
  {"SSL_library_init",  NULL},
  {"SSL_CTX_use_PrivateKey_file", NULL},
  {"SSL_CTX_use_certificate_file",NULL},
  {"SSL_CTX_set_default_passwd_cb",NULL},
  {"SSL_CTX_free",  NULL},
  {"SSL_load_error_strings", NULL},
  {"SSL_CTX_use_certificate_chain_file", NULL},
  {"SSLv23_client_method", NULL},
  {"SSL_pending", NULL},
  {"SSL_CTX_set_verify", NULL},
  {"SSL_shutdown",   NULL},
  {NULL,    NULL}
};

// Similar array as ssl_sw. These functions could be located in different lib.
static struct ssl_func crypto_sw[] = {
  {"CRYPTO_num_locks",  NULL},
  {"CRYPTO_set_locking_callback", NULL},
  {"CRYPTO_set_id_callback", NULL},
  {"ERR_get_error",  NULL},
  {"ERR_error_string", NULL},
  {NULL,    NULL}
};

static pthread_mutex_t *ssl_mutexes;

static int sslize(struct mg_connection *conn, SSL_CTX *s, int (*func)(SSL *)) {
  return (conn->ssl = SSL_new(s)) != NULL &&
    SSL_set_fd(conn->ssl, conn->client.sock) == 1 &&
    func(conn->ssl) == 1;
}

// Return OpenSSL error message
static const char *ssl_error(void) {
  unsigned long err;
  err = ERR_get_error();
  return err == 0 ? "" : ERR_error_string(err, NULL);
}

static void ssl_locking_callback(int mode, int mutex_num, const char *file,
                                 int line) {
  (void) line;
  (void) file;

  if (mode & 1) {  // 1 is CRYPTO_LOCK
    (void) pthread_mutex_lock(&ssl_mutexes[mutex_num]);
  } else {
    (void) pthread_mutex_unlock(&ssl_mutexes[mutex_num]);
  }
}

static unsigned long ssl_id_callback(void) {
  return (unsigned long) pthread_self();
}

#if !defined(NO_SSL_DL)
static int load_dll(struct mg_context *ctx, const char *dll_name,
                    struct ssl_func *sw) {
  union {void *p; void (*fp)(void);} u;
  void  *dll_handle;
  struct ssl_func *fp;

  if ((dll_handle = dlopen(dll_name, RTLD_LAZY)) == NULL) {
    cry(fc(ctx), "%s: cannot load %s", __func__, dll_name);
    return 0;
  }

  for (fp = sw; fp->name != NULL; fp++) {
#ifdef _WIN32
    // GetProcAddress() returns pointer to function
    u.fp = (void (*)(void)) dlsym(dll_handle, fp->name);
#else
    // dlsym() on UNIX returns void *. ISO C forbids casts of data pointers to
    // function pointers. We need to use a union to make a cast.
    u.p = dlsym(dll_handle, fp->name);
#endif // _WIN32
    if (u.fp == NULL) {
      cry(fc(ctx), "%s: %s: cannot find %s", __func__, dll_name, fp->name);
      return 0;
    } else {
      fp->ptr = u.fp;
    }
  }

  return 1;
}
#endif // NO_SSL_DL

// Dynamically load SSL library. Set up ctx->ssl_ctx pointer.
static int set_ssl_option(struct mg_context *ctx) {
  int i, size;
  const char *pem;

  // If PEM file is not specified and the init_ssl callback
  // is not specified, skip SSL initialization.
  if ((pem = ctx->config[SSL_CERTIFICATE]) == NULL) {
    //  MG_INIT_SSL
    //  ctx->callbacks.init_ssl == NULL) {
    return 1;
  }

#if !defined(NO_SSL_DL)
  if (!load_dll(ctx, SSL_LIB, ssl_sw) ||
      !load_dll(ctx, CRYPTO_LIB, crypto_sw)) {
    return 0;
  }
#endif // NO_SSL_DL

  // Initialize SSL library
  SSL_library_init();
  SSL_load_error_strings();

  if ((ctx->ssl_ctx = SSL_CTX_new(SSLv23_server_method())) == NULL) {
    cry(fc(ctx), "SSL_CTX_new (server) error: %s", ssl_error());
    return 0;
  }

  // If user callback returned non-NULL, that means that user callback has
  // set up certificate itself. In this case, skip sertificate setting.
  // MG_INIT_SSL
  if (SSL_CTX_use_certificate_file(ctx->ssl_ctx, pem, 1) == 0 ||
      SSL_CTX_use_PrivateKey_file(ctx->ssl_ctx, pem, 1) == 0) {
    cry(fc(ctx), "%s: cannot open %s: %s", __func__, pem, ssl_error());
    return 0;
  }

  if (pem != NULL) {
    (void) SSL_CTX_use_certificate_chain_file(ctx->ssl_ctx, pem);
  }

  // Initialize locking callbacks, needed for thread safety.
  // http://www.openssl.org/support/faq.html#PROG1
  size = sizeof(pthread_mutex_t) * CRYPTO_num_locks();
  if ((ssl_mutexes = (pthread_mutex_t *) malloc((size_t)size)) == NULL) {
    cry(fc(ctx), "%s: cannot allocate mutexes: %s", __func__, ssl_error());
    return 0;
  }

  for (i = 0; i < CRYPTO_num_locks(); i++) {
    pthread_mutex_init(&ssl_mutexes[i], NULL);
  }

  CRYPTO_set_locking_callback(&ssl_locking_callback);
  CRYPTO_set_id_callback(&ssl_id_callback);

  return 1;
}

static void uninitialize_ssl(struct mg_context *ctx) {
  int i;
  if (ctx->ssl_ctx != NULL) {
    CRYPTO_set_locking_callback(NULL);
    for (i = 0; i < CRYPTO_num_locks(); i++) {
      pthread_mutex_destroy(&ssl_mutexes[i]);
    }
    CRYPTO_set_locking_callback(NULL);
    CRYPTO_set_id_callback(NULL);
  }
}
#endif // !NO_SSL

static int set_gpass_option(struct mg_context *ctx) {
  struct file file = STRUCT_FILE_INITIALIZER;
  const char *path = ctx->config[GLOBAL_PASSWORDS_FILE];
  if (path != NULL && !mg_stat(path, &file)) {
    cry(fc(ctx), "Cannot open %s: %s", path, strerror(ERRNO));
    return 0;
  }
  return 1;
}

static int set_acl_option(struct mg_context *ctx) {
  return check_acl(ctx, (uint32_t) 0x7f000001UL) != -1;
}

static void reset_per_request_attributes(struct mg_connection *conn) {
  conn->path_info = NULL;
  conn->num_bytes_sent = conn->num_bytes_read = 0;
  conn->status_code = -1;
  conn->must_close = conn->request_len = conn->throttle = 0;
}

static void close_socket_gracefully(struct mg_connection *conn) {
#if defined(_WIN32)
  char buf[MG_BUF_LEN];
  int n;
#endif
  struct linger linger;

  // Set linger option to avoid socket hanging out after close. This prevent
  // ephemeral port exhaust problem under high QPS.
  linger.l_onoff = 1;
  linger.l_linger = 1;
  setsockopt(conn->client.sock, SOL_SOCKET, SO_LINGER,
             (char *) &linger, sizeof(linger));

  // Send FIN to the client
  shutdown(conn->client.sock, SHUT_WR);
  set_non_blocking_mode(conn->client.sock);

#if defined(_WIN32)
  // Read and discard pending incoming data. If we do not do that and close the
  // socket, the data in the send buffer may be discarded. This
  // behaviour is seen on Windows, when client keeps sending data
  // when server decides to close the connection; then when client
  // does recv() it gets no data back.
  do {
    n = pull(NULL, conn, buf, sizeof(buf));
  } while (n > 0);
#endif

  // Now we know that our FIN is ACK-ed, safe to close
  closesocket(conn->client.sock);
}

static void close_connection(struct mg_connection *conn) {
  conn->must_close = 1;

#ifndef NO_SSL
  if (conn->ssl != NULL) {
    // Run SSL_shutdown twice to ensure completly close SSL connection
    SSL_shutdown(conn->ssl);
    SSL_free(conn->ssl);
    conn->ssl = NULL;
  }
#endif
  if (conn->client.sock != INVALID_SOCKET) {
    close_socket_gracefully(conn);
    conn->client.sock = INVALID_SOCKET;
  }
}

void mg_close_connection(struct mg_connection *conn) {
#ifndef NO_SSL
  if (conn->client_ssl_ctx != NULL) {
    SSL_CTX_free((SSL_CTX *) conn->client_ssl_ctx);
  }
#endif
  close_connection(conn);
  free(conn);
}

struct mg_connection *mg_connect(const char *host, int port, int use_ssl,
                                 char *ebuf, size_t ebuf_len) {
  static struct mg_context fake_ctx;
  struct mg_connection *conn = NULL;
  SOCKET sock;

  if ((sock = conn2(host, port, use_ssl, ebuf, ebuf_len)) == INVALID_SOCKET) {
  } else if ((conn = (struct mg_connection *)
              calloc(1, sizeof(*conn) + MAX_REQUEST_SIZE)) == NULL) {
    snprintf(ebuf, ebuf_len, "calloc(): %s", strerror(ERRNO));
    closesocket(sock);
#ifndef NO_SSL
  } else if (use_ssl && (conn->client_ssl_ctx =
                         SSL_CTX_new(SSLv23_client_method())) == NULL) {
    snprintf(ebuf, ebuf_len, "SSL_CTX_new error");
    closesocket(sock);
    free(conn);
    conn = NULL;
#endif // NO_SSL
  } else {
    socklen_t len = sizeof(struct sockaddr);
    conn->buf_size = MAX_REQUEST_SIZE;
    conn->buf = (char *) (conn + 1);
    conn->ctx = &fake_ctx;
    conn->client.sock = sock;
    getsockname(sock, &conn->client.rsa.sa, &len);
    conn->client.is_ssl = use_ssl;
#ifndef NO_SSL
    if (use_ssl) {
      // SSL_CTX_set_verify call is needed to switch off server certificate
      // checking, which is off by default in OpenSSL and on in yaSSL.
      SSL_CTX_set_verify(conn->client_ssl_ctx, 0, 0);
      sslize(conn, conn->client_ssl_ctx, SSL_connect);
    }
#endif
  }

  return conn;
}

static int is_valid_uri(const char *uri) {
  // Conform to http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.1.2
  // URI can be an asterisk (*) or should start with slash.
  return uri[0] == '/' || (uri[0] == '*' && uri[1] == '\0');
}

static int getreq(struct mg_connection *conn, char *ebuf, size_t ebuf_len) {
  const char *cl;

  ebuf[0] = '\0';
  reset_per_request_attributes(conn);
  conn->request_len = read_request(NULL, conn, conn->buf, conn->buf_size,
                                   &conn->data_len);
  assert(conn->request_len < 0 || conn->data_len >= conn->request_len);

  if (conn->request_len == 0 && conn->data_len == conn->buf_size) {
    snprintf(ebuf, ebuf_len, "%s", "Request Too Large");
  } else if (conn->request_len <= 0) {
    snprintf(ebuf, ebuf_len, "%s", "Client closed connection");
  } else if (parse_http_message(conn->buf, conn->buf_size,
                                &conn->request_info) <= 0) {
    snprintf(ebuf, ebuf_len, "Bad request: [%.*s]", conn->data_len, conn->buf);
  } else {
    // Request is valid
    if ((cl = get_header(&conn->request_info, "Content-Length")) != NULL) {
      conn->content_len = strtoll(cl, NULL, 10);
    } else if (!mg_strcasecmp(conn->request_info.request_method, "POST") ||
               !mg_strcasecmp(conn->request_info.request_method, "PUT")) {
      conn->content_len = -1;
    } else {
      conn->content_len = 0;
    }
    conn->birth_time = time(NULL);
  }
  return ebuf[0] == '\0';
}

struct mg_connection *mg_download(const char *host, int port, int use_ssl,
                                  char *ebuf, size_t ebuf_len,
                                  const char *fmt, ...) {
  struct mg_connection *conn;
  va_list ap;

  va_start(ap, fmt);
  ebuf[0] = '\0';
  if ((conn = mg_connect(host, port, use_ssl, ebuf, ebuf_len)) == NULL) {
  } else if (mg_vprintf(conn, fmt, ap) <= 0) {
    snprintf(ebuf, ebuf_len, "%s", "Error sending request");
  } else {
    getreq(conn, ebuf, ebuf_len);
  }
  if (ebuf[0] != '\0' && conn != NULL) {
    mg_close_connection(conn);
    conn = NULL;
  }

  return conn;
}

static void process_new_connection(struct mg_connection *conn) {
  struct mg_request_info *ri = &conn->request_info;
  int keep_alive_enabled, keep_alive, discard_len;
  char ebuf[100];

  keep_alive_enabled = !strcmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes");
  keep_alive = 0;

  // Important: on new connection, reset the receiving buffer. Credit goes