From 906923ad3f2ecb2c73d286924e2ac05f8f3ae502 Mon Sep 17 00:00:00 2001
From: Anton Kling <anton@kling.gg>
Date: Mon, 9 Dec 2024 17:29:07 +0100
Subject: tcpserver: Add the basics of tcpserver

---
 userland/tcpserver/tcpserver.c | 78 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 userland/tcpserver/tcpserver.c

(limited to 'userland/tcpserver/tcpserver.c')

diff --git a/userland/tcpserver/tcpserver.c b/userland/tcpserver/tcpserver.c
new file mode 100644
index 0000000..90660df
--- /dev/null
+++ b/userland/tcpserver/tcpserver.c
@@ -0,0 +1,78 @@
+#include <arpa/inet.h>
+#include <assert.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+void usage(char *program_name) {
+  fprintf(stderr, "Usage: %s host port program [arg...]\n", program_name);
+}
+
+int main(int argc, char **argv) {
+  if (argc < 4) {
+    usage(*argv);
+    return 1;
+  }
+  char *host = *(argv + 1);
+  if ('-' == *host) {
+    fprintf(stderr, "Sorry, command line arguments are not supported\n");
+    return 1;
+  }
+  char *port = *(argv + 2);
+  char *program = *(argv + 3);
+  // The arguments beign at argv + 4 but
+  // argv[0] should be "program" anyways.
+  char **program_arguments = argv + 3;
+
+  int port_number = atoi(port);
+  if (0 == port_number) {
+    fprintf(stderr, "Invalid port: %s\n", port);
+    return 1;
+  }
+
+  int sockfd = socket(AF_INET, SOCK_STREAM, 0);
+  if (-1 == sockfd) {
+    perror("socket");
+    return 1;
+  }
+
+  struct sockaddr_in servaddr;
+  memset(&servaddr, 0, sizeof(servaddr));
+
+  servaddr.sin_family = AF_INET;
+  servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
+  servaddr.sin_port = htons(port_number);
+
+  if (-1 == bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr))) {
+    perror("bind");
+    return 1;
+  }
+
+  for (;;) {
+    struct sockaddr_in cli;
+    socklen_t len = sizeof(cli);
+    int connfd = accept(sockfd, (struct sockaddr *)&cli, &len);
+    if (-1 == connfd) {
+      perror("accept");
+      continue;
+    }
+
+    if (0 == fork()) {
+      dup2(connfd, 0);
+      dup2(connfd, 1);
+      assert(-1 == execv(program, program_arguments));
+      perror("execv");
+      return 1;
+    }
+    close(connfd);
+  }
+
+  close(sockfd);
+  return 0;
+}
-- 
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