Add IP address conversion helpers

Fixes #47

libc/sock/inet_addr.c

@@ -0,0 +1,32 @@
+/*-*- 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/sock/sock.h"
+
+/**
+ * Converts dotted IPv4 address string to network order binary.
+ * @see inet_aton()
+ */
+uint32_t inet_addr(const char *s) {
+  struct in_addr in;
+  if (inet_aton(s, &in)) {
+    return in.s_addr;
+  } else {
+    return -1;
+  }
+}

libc/sock/inet_aton.c

@@ -0,0 +1,69 @@
+/*-*- 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│
+╚──────────────────────────────────────────────────────────────────────────────╝
+│                                                                              │
+│  Musl Libc                                                                   │
+│  Copyright © 2005-2014 Rich Felker, et al.                                   │
+│                                                                              │
+│  Permission is hereby granted, free of charge, to any person obtaining       │
+│  a copy of this software and associated documentation files (the             │
+│  "Software"), to deal in the Software without restriction, including         │
+│  without limitation the rights to use, copy, modify, merge, publish,         │
+│  distribute, sublicense, and/or sell copies of the Software, and to          │
+│  permit persons to whom the Software is furnished to do so, subject to       │
+│  the following conditions:                                                   │
+│                                                                              │
+│  The above copyright notice and this permission notice shall be              │
+│  included in all copies or substantial portions of the Software.             │
+│                                                                              │
+│  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             │
+│  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          │
+│  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      │
+│  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        │
+│  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        │
+│  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           │
+│  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      │
+│                                                                              │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/fmt/conv.h"
+#include "libc/sock/sock.h"
+#include "libc/str/str.h"
+
+asm(".ident\t\"\\n\\n\
+Musl libc (MIT License)\\n\
+Copyright 2005-2014 Rich Felker, et. al.\"");
+asm(".include \"libc/disclaimer.inc\"");
+
+/**
+ * Converts dotted IPv4 address string to network order binary.
+ */
+int inet_aton(const char *s0, struct in_addr *dest) {
+  const char *s = s0;
+  unsigned char *d = (void *)dest;
+  unsigned long a[4] = {0};
+  char *z;
+  int i;
+  for (i = 0; i < 4; i++) {
+    a[i] = strtoul(s, &z, 0);
+    if (z == s || (*z && *z != '.') || !isdigit(*s)) return 0;
+    if (!*z) break;
+    s = z + 1;
+  }
+  if (i == 4) return 0;
+  switch (i) {
+    case 0:
+      a[1] = a[0] & 0xffffff;
+      a[0] >>= 24;
+    case 1:
+      a[2] = a[1] & 0xffff;
+      a[1] >>= 16;
+    case 2:
+      a[3] = a[2] & 0xff;
+      a[2] >>= 8;
+  }
+  for (i = 0; i < 4; i++) {
+    if (a[i] > 255) return 0;
+    d[i] = a[i];
+  }
+  return 1;
+}

libc/sock/inet_ntoa.c

@@ -0,0 +1,36 @@
+/*-*- 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/fmt/itoa.h"
+#include "libc/sock/sock.h"
+
+/**
+ * Converts IPv4 network address to array.
+ */
+char *inet_ntoa(struct in_addr in) {
+  static char buf[16];
+  char *p = buf;
+  p += int64toarray_radix10((in.s_addr >> 000) & 255, p);
+  *p++ = '.';
+  p += int64toarray_radix10((in.s_addr >> 010) & 255, p);
+  *p++ = '.';
+  p += int64toarray_radix10((in.s_addr >> 020) & 255, p);
+  *p++ = '.';
+  p += int64toarray_radix10((in.s_addr >> 030) & 255, p);
+  return buf;
+}

libc/sock/sock.h

@@ -65,7 +65,10 @@ struct msghdr {            /* Linux+NT ABI */
 };
 
 const char *inet_ntop(int, const void *, char *, uint32_t);
-int inet_pton(int af, const char *, void *);
+int inet_aton(const char *, struct in_addr *);
+int inet_pton(int, const char *, void *);
+uint32_t inet_addr(const char *);
+char *inet_ntoa(struct in_addr);
 int parseport(const char *);
 
 int socket(int, int, int) nodiscard;

test/libc/sock/inet_ntoa_test.c

@@ -0,0 +1,26 @@
+/*-*- 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/sock/sock.h"
+#include "libc/testlib/testlib.h"
+
+TEST(inet_ntoa, test) {
+  struct in_addr s;
+  EXPECT_EQ(0x04030201, (s.s_addr = inet_addr("1.2.3.4")));
+  EXPECT_STREQ("1.2.3.4", inet_ntoa(s));
+}