Make more major improvements to redbean

- POSIX regular expressions for Lua
- Improved protocol parsing and encoding
- Additional APIs for ZIP storage retrieval
- Fix st_mode issue on NT for regular files
- Generalized APIs for URL and Host handling
- Worked out the kinks in resource resolution
- Allow for custom error pages like /404.html

net/http/isacceptablehost.c

@@ -0,0 +1,81 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/str/str.h"
+#include "net/http/http.h"
+
+/**
+ * Returns true if host seems legit.
+ *
+ * This function may be called after ParseUrl() or ParseHost() has
+ * already handled things like percent encoding. There's currently
+ * no support for IPv6 and IPv7.
+ *
+ * Here's examples of permitted inputs:
+ *
+ * - ""
+ * - 1.2.3.4
+ * - 1.2.3.4.arpa
+ * - localservice
+ * - hello.example
+ * - _hello.example
+ * - -hello.example
+ * - hi-there.example
+ *
+ * Here's some examples of forbidden inputs:
+ *
+ * - ::1
+ * - 1.2.3
+ * - 1.2.3.4.5
+ * - .hi.example
+ * - hi..example
+ *
+ * @param n if -1 implies strlen
+ */
+bool IsAcceptableHost(const char *s, size_t n) {
+  size_t i;
+  bool isip;
+  int c, b, j;
+  if (n == -1) n = s ? strlen(s) : 0;
+  if (!n) return true;
+  for (isip = true, b = j = i = 0; i < n; ++i) {
+    c = s[i] & 255;
+    if (c == '.' && (!i || s[i - 1] == '.')) {
+      return false;
+    } else if (!(isalnum(c) || c == '-' || c == '_' || c == '.')) {
+      return false;
+    }
+    if (isip) {
+      if (isdigit(c)) {
+        b *= 10;
+        b += c - '0';
+        if (b > 255) {
+          return false;
+        }
+      } else if (c == '.') {
+        b = 0;
+        ++j;
+      } else {
+        isip = false;
+      }
+    }
+  }
+  if (isip && j != 3) return false;
+  if (i && s[i - 1] == '.') return false;
+  return true;
+}