examples,pkgs,pkgs.ch-proxy: init

default.nix

@@ -0,0 +1,57 @@
+let
+  pkgs = import <nixpkgs> { };
+  inherit (pkgs) lib;
+  dirToAttrs =
+    root: patterns: f:
+    lib.listToAttrs (
+      lib.concatMap (
+        dirent:
+        let
+          fname = dirent.name;
+          typ = dirent.value;
+          fpath = root + "/${fname}";
+          doMatch =
+            pat:
+            let
+              match = pat fpath fname typ;
+              value = f match fpath typ;
+            in
+            if match == null then [ ] else [ (lib.nameValuePair match value) ];
+        in
+        (lib.take 1 (lib.concatMap (doMatch) patterns))
+      ) (lib.attrsToList (builtins.readDir root))
+    );
+in
+{
+  examples =
+    dirToAttrs ./examples
+      [
+        (
+          path: fname: _:
+          lib.strings.removeSuffix ".nix" fname
+        )
+      ]
+      (
+        name: fpath: _:
+        import <nixpkgs/nixos/lib/eval-config.nix> { modules = [ fpath ]; }
+      );
+  pkgs = lib.makeScope pkgs.newScope (
+    self:
+    dirToAttrs ./pkgs
+      [
+        (
+          path: fname: _:
+          lib.strings.removeSuffix ".nix" fname
+        )
+      ]
+      (
+        name: fpath: typ:
+        if typ == "regular" then
+          self.callPackage fpath { }
+        else if typ == "directory" && builtins.pathExists (fpath + "/package.nix") then
+          self.callPackage (fpath + "/package.nix") { }
+        else
+          null
+      )
+  );
+}

pkgs/ch-proxy/meson.build

@@ -0,0 +1,3 @@
+project('ch-proxy', 'c')
+
+executable('ch-proxy', 'proxy.c', install: true)

pkgs/ch-proxy/package.nix

@@ -0,0 +1,26 @@
+{
+  lib,
+  stdenv,
+  meson,
+  ninja,
+}:
+
+stdenv.mkDerivation {
+  pname = "ch-proxy";
+  version = "0.0.0";
+  nativeBuildInputs = [
+    meson
+    ninja
+  ];
+  src =
+    let
+      fs = lib.fileset;
+    in
+    fs.toSource {
+      fileset = fs.unions [
+        ./proxy.c
+        ./meson.build
+      ];
+      root = ./.;
+    };
+}

pkgs/ch-proxy/proxy.c

@@ -0,0 +1,176 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/socket.h>
+#include <sys/un.h>
+
+struct msghdr mk_msghdr();
+int ch_connect(const char*, const char*);
+ssize_t send_fd(int, int);
+
+#define _WRITE_CONFIRM(fd, buf, buflen) {if (write((fd), (buf), (buflen)) != (buflen)) { perror("ch-proxy/write/partial write"); exit(EXIT_FAILURE); }}
+
+void print_usage() {
+    fprintf(stderr, "%s",
+            "Usage:\n"
+            "\tch-proxy uvm/$USER_VM_NAME [PORT]\n"
+            "\tch-proxy uuvm/$VM_NAME [PORT]\n"
+            "\tch-proxy vsock-mux%$PATH [PORT]\n");
+}
+
+char *extract_vsock_mux(const char *host_string) {
+    const char PREFIX[] = "vsock-mux%";
+    const ssize_t PREFIX_LEN = sizeof(PREFIX) - 1;
+    if (strncmp(host_string, PREFIX, PREFIX_LEN) == 0) {
+        return strdup(&host_string[PREFIX_LEN]);
+    }
+    return NULL;
+}
+
+char *extract_uvm(const char *host_string) {
+    const char PREFIX[] = "uuvm/";
+    const ssize_t PREFIX_LEN = sizeof(PREFIX) - 1;
+
+    const char *home = getenv("HOME") != NULL ? getenv("HOME") : "./.";
+
+    if (strncmp(host_string, PREFIX, PREFIX_LEN) != 0) {
+        return NULL;
+    }
+
+    char *result;
+    if (asprintf(&result, "%s/uvms/%s/CONNECT.sock", home, &host_string[PREFIX_LEN]) == -1) {
+        perror("ch-proxy/extract_uvm");
+        exit(EXIT_FAILURE);
+    }
+
+    return result;
+}
+
+char *extract_muvm(const char *host_string) {
+    const char PREFIX[] = "uvm/";
+    const ssize_t PREFIX_LEN = sizeof(PREFIX) - 1;
+
+
+    if (strncmp(host_string, PREFIX, PREFIX_LEN) != 0) {
+        return NULL;
+    }
+
+    char *result;
+    if (asprintf(&result, "/var/lib/microvms/%s/CONNECT.sock", &host_string[PREFIX_LEN]) == -1) {
+        perror("ch-proxy/extract_muvm");
+        exit(EXIT_FAILURE);
+    }
+
+    return result;
+}
+
+int main(int argc, char** argv) {
+    if (!(2 <= argc && argc <= 3)) {
+        fprintf(stderr, "%s: Wrong # of arguments: %d\n", argv[0], argc);
+        print_usage();
+        return 1;
+    }
+
+    const char PORT_DEFAULT[] = "22";
+
+    const char *ssh_host = argv[1];
+    const char *port_string = argc == 3 ? argv[2] : PORT_DEFAULT;
+
+    char *path_un;
+    if ((path_un = extract_uvm(ssh_host)) != NULL) {
+    } else if ((path_un = extract_muvm(ssh_host)) != NULL) {
+    } else if ((path_un = extract_vsock_mux(ssh_host)) != NULL) {
+    } else {
+        fprintf(stderr, "ch-proxy/main: unexpected host stirng format: %s\n", ssh_host);
+        print_usage();
+        return EXIT_FAILURE;
+    }
+
+    const int s = ch_connect(path_un, port_string);
+    if (s == -1) {
+        perror("ssh-vsock-proxy/main/ch_connect");
+        return EXIT_FAILURE;
+    };
+
+    if (send_fd(1, s) == -1) {
+        perror("ssh-vsock-proxy/main/send_fd");
+        return EXIT_FAILURE;
+    }
+    return 0;
+}
+
+struct msghdr mk_msghdr() {
+    struct msghdr msg;
+    memset(&msg, 0, sizeof(msg));
+
+    return msg;
+}
+
+int ch_connect(const char *path, const char *port) {
+    int s = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (s == -1) {
+        perror("ch-proxy/ch_connect/bind");
+        return -1;
+    }
+
+    struct sockaddr_un a;
+    a.sun_family = AF_UNIX;
+    strcpy(a.sun_path, path);
+
+    if (connect(s, (struct sockaddr*) &a, sizeof(a)) == -1) {
+        char *err_msg;
+        if (asprintf(&err_msg, "ch-proxy/ch_connect/connect(\"%s\")", path) == -1) {
+            perror("ch-proxy/ch_connect/while printing connect() error");
+            exit(EXIT_FAILURE);
+        }
+        perror(err_msg);
+        exit(EXIT_FAILURE);
+    }
+
+    const char CMD[] = "CONNECT ";
+    const int CMD_LEN = sizeof(CMD) - 1;
+
+    _WRITE_CONFIRM(s, CMD, CMD_LEN);
+    _WRITE_CONFIRM(s, port, strlen(port));
+    _WRITE_CONFIRM(s, "\n", 1);
+
+    return s;
+}
+
+ssize_t send_fd(int dst_fd, int fd) {
+    struct msghdr msg = mk_msghdr();
+
+    /* openssh expects to receive a dummy length=1 iovec? */
+    char ch;
+    struct iovec vec;
+    vec.iov_base = &ch;
+    vec.iov_len = 1;
+    msg.msg_iov = &vec;
+    msg.msg_iovlen = 1;
+
+    union {
+        struct cmsghdr align;
+        char buf[CMSG_SPACE(sizeof(int))];
+    } u;
+
+    msg.msg_control = u.buf;
+    msg.msg_controllen = sizeof(u.buf);
+
+    struct cmsghdr *cmptr;
+    cmptr = CMSG_FIRSTHDR(&msg);
+
+    if (cmptr == NULL) {
+        fprintf(stderr, "ch-proxy/send_fd/CMSG_FIRSTHDR: failed to initialize msg_control\n");
+        exit(EXIT_FAILURE);
+    }
+
+    cmptr->cmsg_len = CMSG_LEN(sizeof(int));
+    cmptr->cmsg_level = SOL_SOCKET;
+    cmptr->cmsg_type = SCM_RIGHTS;
+    *((int*) CMSG_DATA(cmptr)) = fd;
+
+    return (sendmsg(dst_fd, &msg, 0));
+}