Make improvements

- Clean up sigaction() code - Add a port scanner example - Introduce a ParseCidr() API - Clean up our futex abstraction code - Fix a harmless integer overflow in ParseIp() - Use kernel semaphores on NetBSD to make threads much faster
2025-05-22 21:32:31 +00:00 · 2022-11-07 02:22:09 -08:00 · 2022-11-07 02:22:09 -08:00 · c995838e5c
commit c995838e5c
parent 539bddce8c
107 changed files with 1085 additions and 492 deletions
--- a/examples/portscan.c
+++ b/examples/portscan.c
@ -0,0 +1,127 @@
+#if 0
+/*─────────────────────────────────────────────────────────────────╗
+│ To the extent possible under law, Justine Tunney has waived      │
+│ all copyright and related or neighboring rights to this file,    │
+│ as it is written in the following disclaimers:                   │
+│   • http://unlicense.org/                                        │
+│   • http://creativecommons.org/publicdomain/zero/1.0/            │
+╚─────────────────────────────────────────────────────────────────*/
+#endif
+#include "libc/assert.h"
+#include "libc/calls/calls.h"
+#include "libc/calls/struct/timeval.h"
+#include "libc/errno.h"
+#include "libc/fmt/conv.h"
+#include "libc/fmt/fmt.h"
+#include "libc/mem/alloca.h"
+#include "libc/runtime/runtime.h"
+#include "libc/sock/sock.h"
+#include "libc/sock/struct/sockaddr.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/af.h"
+#include "libc/sysv/consts/ipproto.h"
+#include "libc/sysv/consts/so.h"
+#include "libc/sysv/consts/sock.h"
+#include "libc/sysv/consts/sol.h"
+#include "net/http/ip.h"
+
+/**
+ * @fileoverview fast local network port scanner, e.g.
+ *
+ *     make -j8 o//examples/portscan.com
+ *     o//examples/portscan.com 10.10.10.0/24 22
+ */
+
+const char *FormatIp(char buf[16], uint32_t ip) {
+  snprintf(buf, 16, "%hhu.%hhu.%hhu.%hhu", ip >> 24, ip >> 16, ip >> 8, ip);
+  return buf;
+}
+
+#define FormatIp(x) FormatIp(alloca(16), x)
+
+int main(int argc, char *argv[]) {
+  int port;
+  struct Cidr in;
+  uint32_t netmask;
+  const char *status;
+  struct timeval timeout;
+  uint32_t network_address;
+  uint32_t last_host_address;
+  uint32_t first_host_address;
+
+  if (argc != 3) {
+  PrintUsage:
+    fprintf(stderr,
+            "usage:   %s IP/CIDR PORT\n"
+            "example: %s 192.168.0.0/24 22\n",
+            argv[0], argv[0]);
+    return 1;
+  }
+
+  in = ParseCidr(argv[1], -1);
+  if (in.addr == -1) {
+    fprintf(stderr, "error: bad ip/cidr\n");
+    goto PrintUsage;
+  }
+
+  port = atoi(argv[2]);
+  if (!(1 <= port && port <= 65535)) {
+    fprintf(stderr, "error: bad port\n");
+    goto PrintUsage;
+  }
+
+  if (in.cidr > 30) {
+    fprintf(stderr, "error: maximum supported cidr is 30\n");
+    goto PrintUsage;
+  }
+
+  if (in.cidr < 22) {
+    fprintf(stderr, "error: minimum cidr support right now is 22\n");
+    goto PrintUsage;
+  }
+
+  netmask = -1u << (32 - in.cidr);
+  network_address = in.addr & netmask;
+  first_host_address = network_address + 1;
+  last_host_address = (network_address | ~netmask) - 1;
+
+  assert(last_host_address > first_host_address);
+  assert(last_host_address - first_host_address < 1024);
+
+  fprintf(stderr, "scanning %s through %s\n", FormatIp(first_host_address),
+          FormatIp(last_host_address));
+
+  timeout = timeval_frommillis(100);
+  for (int64_t ip = first_host_address; ip <= last_host_address; ++ip) {
+    if (!fork()) {
+      socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+      setsockopt(3, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout));
+      setsockopt(3, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout));
+      if (!connect(3,
+                   (struct sockaddr *)&(struct sockaddr_in){
+                       .sin_family = AF_INET,
+                       .sin_addr.s_addr = htonl(ip),
+                       .sin_port = htons(port),
+                   },
+                   sizeof(struct sockaddr_in))) {
+        status = "open";
+      } else if (errno == ECONNREFUSED) {
+        status = "closed";
+      } else if (errno != EINPROGRESS) {
+        status = _strerrno(errno);
+      } else {
+        status = 0;
+      }
+      if (status) {
+        printf("%-15s %s\n", FormatIp(ip), status);
+      }
+      _Exit(0);
+    }
+  }
+  for (;;) {
+    if (wait(0) == -1 && errno == ECHILD) {
+      break;
+    }
+  }
+}