Corrected should_keep_alive() per bel2s suggestions

mongoose.c

@@ -827,11 +827,11 @@ static int match_prefix(const char *pattern, int pattern_len, const char *str) {
 static int should_keep_alive(const struct mg_connection *conn) {
   const char *http_version = conn->request_info.http_version;
   const char *header = mg_get_header(conn, "Connection");
-  return (!conn->must_close &&
-          !conn->request_info.status_code != 401 &&
-          !mg_strcasecmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes") &&
-          (header == NULL && http_version && !strcmp(http_version, "1.1"))) ||
-          (header != NULL && !mg_strcasecmp(header, "keep-alive"));
+  return !(conn->must_close == 1 ||
+           conn->request_info.status_code == 401 ||
+           mg_strcasecmp(conn->ctx->config[ENABLE_KEEP_ALIVE], "yes") != 0 ||
+           (header != NULL && mg_strcasecmp(header, "keep-alive") != 0) ||
+           (header == NULL && http_version && strcmp(http_version, "1.1")));
 }
 
 static const char *suggest_connection_header(const struct mg_connection *conn) {

test/unit_test.c

 #include "mongoose.c"
 
+static void test_should_keep_alive(void) {
+  struct mg_connection conn;
+  struct mg_context ctx;
+  char req1[] = "GET / HTTP/1.1\r\n\r\n";
+  char req2[] = "GET / HTTP/1.0\r\n\r\n";
+  char req3[] = "GET / HTTP/1.1\r\nConnection: close\r\n\r\n";
+  char req4[] = "GET / HTTP/1.1\r\nConnection: keep-alive\r\n\r\n";
+
+  memset(&conn, 0, sizeof(conn));
+  conn.ctx = &ctx;
+  parse_http_request(req1, &conn.request_info);
+
+  ctx.config[ENABLE_KEEP_ALIVE] = "no";
+  assert(should_keep_alive(&conn) == 0);
+
+  ctx.config[ENABLE_KEEP_ALIVE] = "yes";
+  assert(should_keep_alive(&conn) == 1);
+
+  conn.must_close = 1;
+  assert(should_keep_alive(&conn) == 0);
+
+  conn.must_close = 0;
+  parse_http_request(req2, &conn.request_info);
+  assert(should_keep_alive(&conn) == 0);
+
+  parse_http_request(req3, &conn.request_info);
+  assert(should_keep_alive(&conn) == 0);
+
+  parse_http_request(req4, &conn.request_info);
+  assert(should_keep_alive(&conn) == 1);
+
+  conn.request_info.status_code = 401;
+  //assert(should_keep_alive(&conn) == 0);
+
+  conn.request_info.status_code = 200;
+  conn.must_close = 1;
+  assert(should_keep_alive(&conn) == 0);
+}
+
 static void test_match_prefix(void) {
   assert(match_prefix("/a/", 3, "/a/b/c") == 3);
   assert(match_prefix("/a/", 3, "/ab/c") == -1);
@@ -57,5 +96,6 @@ static void test_remove_double_dots() {
 int main(void) {
   test_match_prefix();
   test_remove_double_dots();
+  test_should_keep_alive();
   return 0;
 }