Implement -T option, throttling functionality

mongoose.1

@@ -91,6 +91,18 @@ Authorization realm. Default: "mydomain.com"
 All files that fully match ssi_pattern are treated as SSI.
 Unknown SSI directives are silently ignored. Currently, two SSI directives
 are supported, "include" and "exec".  Default: "**.shtml$|**.shtm$"
+.It Fl T Ar throttle
+Limit download speed for clients.
+.Ar throttle
+is a comma-separated list of key=value pairs, where
+key could be a '*' character (limit for all connections), a subnet in form
+x.x.x.x/mask (limit for a given subnet, for example 10.0.0.0/8), or an
+URI prefix pattern (limit for the set of URIs, for example /foo/**). The value
+is a floating-point number of bytes per second, optionally followed by a
+`k' or `m' character, meaning kilobytes and megabytes respectively. A limit
+of 0 means unlimited rate. The last matching rule wins. For example,
+"*=1k,10.0.0.0/8" means limit everybody to 1 kilobyte per second, but give
+people from 10/8 subnet unlimited speed. Default: ""
 .It Fl a Ar access_log_file
 Access log file. Default: "", no logging is done.
 .It Fl d Ar enable_directory_listing

mongoose.c

@@ -131,6 +131,7 @@ typedef long off_t;
 #define read(x, y, z) _read((x), (y), (unsigned) z)
 #define flockfile(x) EnterCriticalSection(&global_log_file_lock)
 #define funlockfile(x) LeaveCriticalSection(&global_log_file_lock)
+#define sleep(x) Sleep((x) * 1000)
 
 #if !defined(fileno)
 #define fileno(x) _fileno(x)
@@ -426,7 +427,7 @@ struct socket {
 // NOTE(lsm): this enum shoulds be in sync with the config_options below.
 enum {
   CGI_EXTENSIONS, CGI_ENVIRONMENT, PUT_DELETE_PASSWORDS_FILE, CGI_INTERPRETER,
-  PROTECT_URI, AUTHENTICATION_DOMAIN, SSI_EXTENSIONS,
+  PROTECT_URI, AUTHENTICATION_DOMAIN, SSI_EXTENSIONS, THROTTLE,
   ACCESS_LOG_FILE, ENABLE_DIRECTORY_LISTING, ERROR_LOG_FILE,
   GLOBAL_PASSWORDS_FILE, INDEX_FILES, ENABLE_KEEP_ALIVE, ACCESS_CONTROL_LIST,
   EXTRA_MIME_TYPES, LISTENING_PORTS, DOCUMENT_ROOT, SSL_CERTIFICATE,
@@ -442,6 +443,7 @@ static const char *config_options[] = {
   "P", "protect_uri", NULL,
   "R", "authentication_domain", "mydomain.com",
   "S", "ssi_pattern", "**.shtml$|**.shtm$",
+  "T", "throttle", NULL,
   "a", "access_log_file", NULL,
   "d", "enable_directory_listing", "yes",
   "e", "error_log_file", NULL,
@@ -453,7 +455,7 @@ static const char *config_options[] = {
   "p", "listening_ports", "8080",
   "r", "document_root",  ".",
   "s", "ssl_certificate", NULL,
-  "t", "num_threads", "10",
+  "t", "num_threads", "20",
   "u", "run_as_user", NULL,
   "w", "url_rewrite_patterns", NULL,
   "x", "hide_files_patterns", NULL,
@@ -499,6 +501,9 @@ struct mg_connection {
   int request_len;            // Size of the request + headers in a buffer
   int data_len;               // Total size of data in a buffer
   int status_code;            // HTTP reply status code, e.g. 200
+  int throttle;               // Throttling, bytes/sec. <= 0 means no throttle
+  time_t last_throttle_time;  // Last time throttled data was sent
+  int64_t last_throttle_bytes;// Bytes sent this second
 };
 
 const char **mg_get_valid_option_names(void) {
@@ -1507,8 +1512,41 @@ int mg_read(struct mg_connection *conn, void *buf, size_t len) {
 }
 
 int mg_write(struct mg_connection *conn, const void *buf, size_t len) {
-  return (int) push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
+  time_t now;
+  int64_t n, total, allowed;
+
+  if (conn->throttle > 0) {
+    if ((now = time(NULL)) != conn->last_throttle_time) {
+      conn->last_throttle_time = now;
+      conn->last_throttle_bytes = 0;
+    }
+    allowed = conn->throttle - conn->last_throttle_bytes;
+    if (allowed > (int64_t) len) {
+      allowed = len;
+    }
+    if ((total = push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
+                      (int64_t) allowed)) == allowed) {
+      buf = (char *) buf + total;
+      conn->last_throttle_bytes += total;
+      while (total < (int64_t) len && conn->ctx->stop_flag == 0) {
+        allowed = conn->throttle > (int64_t) len - total ?
+          len - total : conn->throttle;
+        if ((n = push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
+                      (int64_t) allowed)) != allowed) {
+          break;
+        }
+        sleep(1);
+        conn->last_throttle_bytes = allowed;
+        conn->last_throttle_time = time(NULL);
+        buf = (char *) buf + n;
+        total += n;
+      }
+    }
+  } else {
+    total = push(NULL, conn->client.sock, conn->ssl, (const char *) buf,
                  (int64_t) len);
+  }
+  return (int) total;
 }
 
 int mg_printf(struct mg_connection *conn, const char *fmt, ...) {
@@ -3745,6 +3783,53 @@ static int is_websocket_request(const struct mg_connection *conn) {
 }
 #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;
+}
+
 // 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
@@ -3762,6 +3847,10 @@ static void handle_request(struct mg_connection *conn) {
   url_decode(ri->uri, (size_t)uri_len, ri->uri, (size_t)(uri_len + 1), 0);
   remove_double_dots_and_double_slashes(ri->uri);
   stat_result = convert_uri_to_file_name(conn, path, sizeof(path), &st);
+  conn->throttle = set_throttle(conn->ctx->config[THROTTLE],
+                                ntohl(* (uint32_t *)
+                                      &conn->client.rsa.sin.sin_addr),
+                                ri->uri);
 
   DEBUG_TRACE(("%s", ri->uri));
   if (!check_authorization(conn, path)) {
@@ -3973,15 +4062,10 @@ static void log_access(const struct mg_connection *conn) {
   fclose(fp);
 }
 
-static int isbyte(int n) {
-  return n >= 0 && n <= 255;
-}
-
 // 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, const union usa *usa) {
-  int a, b, c, d, n, mask, allowed;
-  char flag;
+  int allowed, flag;
   uint32_t acl_subnet, acl_mask, remote_ip;
   struct vec vec;
   const char *list = ctx->config[ACCESS_CONTROL_LIST];
@@ -3996,28 +4080,13 @@ static int check_acl(struct mg_context *ctx, const union usa *usa) {
   allowed = '-';
 
   while ((list = next_option(list, &vec, NULL)) != NULL) {
-    mask = 32;
-
-    if (sscanf(vec.ptr, "%c%d.%d.%d.%d%n", &flag, &a, &b, &c, &d, &n) != 5) {
+    flag = vec.ptr[0];
+    if (flag != '+' && flag != '-' &&
+        parse_net(&vec.ptr[1], &acl_subnet, &acl_mask) == 0) {
       cry(fc(ctx), "%s: subnet must be [+|-]x.x.x.x[/x]", __func__);
       return -1;
-    } else if (flag != '+' && flag != '-') {
-      cry(fc(ctx), "%s: flag must be + or -: [%s]", __func__, vec.ptr);
-      return -1;
-    } else if (!isbyte(a)||!isbyte(b)||!isbyte(c)||!isbyte(d)) {
-      cry(fc(ctx), "%s: bad ip address: [%s]", __func__, vec.ptr);
-      return -1;
-    } else if (sscanf(vec.ptr + n, "/%d", &mask) == 0) {
-      // Do nothing, no mask specified
-    } else if (mask < 0 || mask > 32) {
-      cry(fc(ctx), "%s: bad subnet mask: %d [%s]", __func__, n, vec.ptr);
-      return -1;
     }
 
-    acl_subnet = ((uint32_t) a << 24) | ((uint32_t) b << 16) |
-      ((uint32_t) c << 8) | d;
-    acl_mask = mask ? 0xffffffffU << (32 - mask) : 0;
-
     if (acl_subnet == (ntohl(remote_ip) & acl_mask)) {
       allowed = flag;
     }
@@ -4205,7 +4274,7 @@ static void reset_per_request_attributes(struct mg_connection *conn) {
   conn->path_info = conn->log_message = NULL;
   conn->num_bytes_sent = conn->consumed_content = 0;
   conn->status_code = -1;
-  conn->must_close = conn->request_len = 0;
+  conn->must_close = conn->request_len = conn->throttle = 0;
 }
 
 static void close_socket_gracefully(struct mg_connection *conn) {

test/unit_test.c

@@ -227,6 +227,34 @@ static void test_mg_get_var(void) {
   ASSERT(mg_get_var(post[0], strlen(post[0]), "x", buf, 0) == -2);
 }
 
+static void test_set_throttle(void) {
+  ASSERT(set_throttle(NULL, 0x0a000001, "/") == 0);
+  ASSERT(set_throttle("10.0.0.0/8=20", 0x0a000001, "/") == 20);
+  ASSERT(set_throttle("10.0.0.0/8=0.5k", 0x0a000001, "/") == 512);
+  ASSERT(set_throttle("10.0.0.0/8=17m", 0x0a000001, "/") == 1048576 * 17);
+  ASSERT(set_throttle("10.0.0.0/8=1x", 0x0a000001, "/") == 0);
+  ASSERT(set_throttle("10.0.0.0/8=5,0.0.0.0/0=10", 0x0a000001, "/") == 10);
+  ASSERT(set_throttle("10.0.0.0/8=5,/foo/**=7", 0x0a000001, "/index") == 5);
+  ASSERT(set_throttle("10.0.0.0/8=5,/foo/**=7", 0x0a000001, "/foo/x") == 7);
+  ASSERT(set_throttle("10.0.0.0/8=5,/foo/**=7", 0x0b000001, "/foxo/x") == 0);
+  ASSERT(set_throttle("10.0.0.0/8=5,*=1", 0x0b000001, "/foxo/x") == 1);
+}
+
+static void test_next_option(void) {
+  const char *p, *list = "x/8,/y**=1;2k,z";
+  struct vec a, b;
+  int i;
+
+  ASSERT(next_option(NULL, &a, &b) == NULL);
+  for (i = 0, p = list; (p = next_option(p, &a, &b)) != NULL; i++) {
+    ASSERT(i != 0 || (a.ptr == list && a.len == 3 && b.len == 0));
+    ASSERT(i != 1 || (a.ptr == list + 4 && a.len == 4 && b.ptr == list + 9 &&
+                      b.len == 4));
+
+    ASSERT(i != 2 || (a.ptr == list + 14 && a.len == 1 && b.len == 0));
+  }
+}
+
 int main(void) {
   test_base64_encode();
   test_match_prefix();
@@ -235,5 +263,7 @@ int main(void) {
   test_parse_http_request();
   test_mg_fetch();
   test_mg_get_var();
+  test_set_throttle();
+  test_next_option();
   return 0;
 }