chore: actually vcs this proj, working on it for monthsmain

1 files changed, 173 insertions, 0 deletions

diff --git a/src/tailnet.c b/src/tailnet.c
new file mode 100644
index 0000000..21a90f6
--- /dev/null
+++ b/src/tailnet.c
@@ -0,0 +1,173 @@
+#include "tailnet.h"
+#include "hoodsgate/hoodsgate.h"
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+DEFINE_PROGRAM_LIST(PROG_TAILSCALE, PROG_SYSCTL, PROG_UFW, PROG_CURL, PROG_NFT)
+
+const char *tailnetMissingProgs[MAX_PROG_COUNT];
+static int _missingProgsCount = 0;
+static char *_kernelOpts[] = {"net.ipv4.ip_forward = 1\n",
+                              "net.ipv6.conf.all.forwarding = 1\n"};
+// filename needs to be 99-tailscale.conf
+static char *_sysctlConf = "/etc/sysctl.d/100-tailscale.conf";
+static char *_sysctlConfFallback = "/etc/sysctl.conf";
+static char *_ufw_file = "/etc/default/ufw";
+
+bool tailnet_is_file_executable_boolean(const char *filepath) {
+  return access(filepath, X_OK) == 0;
+}
+
+bool tailnet_is_program_installed_boolean(const char *program_name) {
+  if (!program_name || strlen(program_name) == 0) {
+    return false;
+  }
+
+  char *path_env = getenv("PATH");
+  if (!path_env) {
+    return false;
+  }
+
+  char path_copy[4096];
+  strncpy(path_copy, path_env, sizeof(path_copy) - 1);
+  path_copy[sizeof(path_copy) - 1] = '\0';
+
+  char *dir = strtok(path_copy, ":");
+  while (dir != NULL) {
+    char fullpath[1024];
+    snprintf(fullpath, sizeof(fullpath), "%s/%s", dir, program_name);
+
+    if (tailnet_is_file_executable_boolean(fullpath)) {
+      return true;
+    }
+    dir = strtok(NULL, ":");
+  }
+  return false;
+}
+
+bool tailnet_check_required_programs_boolean(void) {
+  printf("Checking required programs...\n");
+  bool res = true;
+  for (int i = 0; i < REQUIRED_PROGS_COUNT; i++) {
+    if (!tailnet_is_program_installed_boolean(REQUIRED_PROGS[i])) {
+      int pos = _missingProgsCount;
+      if (pos < MAX_PROG_COUNT) {
+        tailnetMissingProgs[pos] = REQUIRED_PROGS[i];
+        _missingProgsCount++;
+      }
+      printf("  ✗ %s (MISSING)\n", REQUIRED_PROGS[i]);
+      res = false;
+    } else {
+      printf("  ✓ %s\n", REQUIRED_PROGS[i]);
+    }
+  }
+
+  if (res) {
+    printf("All required programs found!\n");
+  } else {
+    printf("\nPlease install missing programs. \n");
+  }
+
+  return res;
+}
+
+bool tailnet_advertise_exit_node_boolean() {
+  const char *conf_file =
+      (access("/etc/sysctl.d/", F_OK) == 0) ? _sysctlConf : _sysctlConfFallback;
+
+  FILE *file = fopen(conf_file, "a");
+  if (!file) {
+    perror("Failed to open file for appending kernel opts forwarding rules");
+    return false;
+  }
+
+  for (int i = 0; i < (int)(sizeof(_kernelOpts) / sizeof(_kernelOpts[0]));
+       i++) {
+    fputs(_kernelOpts[i], file);
+  }
+
+  fclose(file);
+  printf("Wrote kernel forwarding opts to %s\n", conf_file);
+
+  if (!(access(_ufw_file, F_OK) == 0)) {
+    perror("Failed to access ufw default file for file ops");
+    return false;
+  }
+  file = fopen(_ufw_file, "r");
+  if (!file) {
+    perror("Failed to open file to look for ufw foward policy");
+    return false;
+  }
+
+  /* Following is from a comment in /etc/default/ufw
+   * 'Set the default forward policy to ACCEPT, DROP or REJECT.  Please note
+   * that if you change this you will most likely want to adjust your rules
+   * DEFAULT_FORWARD_POLICY="DROP"'
+   */
+  char line[512];
+  bool found = false;
+  while (fgets(line, sizeof(line), file)) {
+    if (strstr(line, "DEFAULT_FORWARD_POLICY") && strstr(line, "DROP")) {
+      printf("Found: %s\n", line);
+      found = true;
+      break;
+    } else if (strstr(line, "DEFAULT_FORWARD_POLICY") &&
+               strstr(line, "ACCEPT")) {
+      printf("Found: %s\nChange your policy rule in /etc/default/ufw to "
+             "DEFAULT_FORWARD_POLICY='DROP'\nand adjust your ufw rules "
+             "accordingly, then rerun",
+             line);
+      exit(1);
+    } else if (strstr(line, "DEFAULT_FORWARD_POLICY") &&
+               strstr(line, "REJECT")) {
+      printf("Found: %s\nChange your policy rule in /etc/default/ufw to "
+             "DEFAULT_FORWARD_POLICY='DROP'\nand adjust your ufw rules "
+             "accordingly, then rerun",
+             line);
+      exit(1);
+    }
+  }
+
+  fclose(file);
+
+  if (found != true) {
+    return false;
+  }
+
+  // tailscaled exit node ivp4 addr
+  char *const tsGetIpv4Addr[] = {PROG_TAILSCALE, "ip", "--4", NULL};
+  char *exitNodeIpv4 =
+      hg_run_command_w_execvp_pchar(PROG_TAILSCALE, tsGetIpv4Addr, NULL);
+
+  if (exitNodeIpv4 == NULL || hg_validate_ipv4_boolean(exitNodeIpv4) == false) {
+    return false;
+  }
+
+  char *flagExitNode = "--exit-node=";
+  strcat(flagExitNode, exitNodeIpv4);
+  char *const tsSetExitNode[] = {PROG_TAILSCALE, "set", flagExitNode,
+                                 "--exit-node-allow-lan-access=true", NULL};
+  char *setExitNode =
+      hg_run_command_w_execvp_pchar(PROG_TAILSCALE, tsSetExitNode, NULL);
+
+  // not sure if the setExitNode returns output; will have to test
+  if (setExitNode == NULL) {
+    return false;
+  }
+
+  char *const tsRunExitNode[] = {PROG_TAILSCALE, "up", NULL};
+  char *runExitNode =
+      hg_run_command_w_execvp_pchar(PROG_TAILSCALE, tsRunExitNode, NULL);
+
+  // not sure if the runExitNode returns output; will have to test
+  if (runExitNode == NULL) {
+    return false;
+  }
+
+  return true;
+}