WIP work on http server

TODO:
  Handling the TCP connection.

Makefile

@@ -1,5 +1,5 @@
 COMMON_FLAGS = -Wall -Wextra -Wpedantic
-DEBUG_FLAGS = -Og
+DEBUG_FLAGS = -Og -g
 RELEASE_FLAGS = -O3 -DNDEBUG
 
 ifdef RELEASE

src/main.c

@@ -1,4 +1,184 @@
+// Standard library includes.
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+// Unix includes.
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <time.h>
+
+#define C_SIMPLE_HTTP_TCP_SOCKET_BACKLOG 64
+#define C_SIMPLE_HTTP_SLEEP_NANOS 1000000
+
+static int C_SIMPLE_HTTP_KEEP_RUNNING = 1;
+
+void C_SIMPLE_HTTP_handle_sigint(int signal) {
+  if (signal == SIGINT) {
+#ifndef NDEBUG
+    puts("Handling SIGINT");
+#endif
+    C_SIMPLE_HTTP_KEEP_RUNNING = 0;
+  }
+}
+
+typedef struct Args {
+  unsigned short flags;
+  unsigned short port;
+} Args;
+
+int is_big_endian(void) {
+  union {
+    int i;
+    char c[4];
+  } bint = {0x01020304};
+
+  return bint.c[0] == 1 ? 1 : 0;
+}
+
+unsigned short u16_be_swap(unsigned short value) {
+  if (is_big_endian()) {
+    return value;
+  } else {
+    return ((value >> 8) & 0xFF) | ((value << 8) & 0xFF00);
+  }
+}
+
+int create_tcp_socket(unsigned short port) {
+  struct sockaddr_in6 ipv6_addr;
+  memset(&ipv6_addr, 0, sizeof(struct sockaddr_in6));
+  ipv6_addr.sin6_family = AF_INET6;
+  ipv6_addr.sin6_port = u16_be_swap(port);
+  ipv6_addr.sin6_addr = in6addr_any;
+
+  int tcp_socket = socket(AF_INET6, SOCK_STREAM | SOCK_NONBLOCK, 6);
+
+  if (tcp_socket == -1) {
+    switch (errno) {
+      case EACCES:
+        puts("ERROR: Socket creation: EACCES");
+        break;
+      case EAFNOSUPPORT:
+        puts("ERROR: Socket creation: EAFNOSUPPORT");
+        break;
+      case EINVAL:
+        puts("ERROR: Socket creation: EINVAL");
+        break;
+      case EMFILE:
+        puts("ERROR: Socket creation: EMFILE");
+        break;
+      case ENOBUFS:
+        puts("ERROR: Socket creation: ENOBUFS");
+        break;
+      case ENOMEM:
+        puts("ERROR: Socket creation: ENOMEM");
+        break;
+      case EPROTONOSUPPORT:
+        puts("ERROR: Socket creation: EPROTONOSUPPORT");
+        break;
+      default:
+        puts("ERROR: Socket creation: Unknown Error");
+        break;
+    }
+    return -1;
+  }
+
+  int ret = bind(tcp_socket, (const struct sockaddr *)&ipv6_addr, sizeof(struct sockaddr_in6));
+  if (ret != 0) {
+    close(tcp_socket);
+    puts("ERROR: Failed to bind socket!");
+    return -1;
+  }
+
+  ret = listen(tcp_socket, C_SIMPLE_HTTP_TCP_SOCKET_BACKLOG);
+
+  if (ret == 0) {
+    return tcp_socket;
+  } else {
+    switch (errno) {
+      case EADDRINUSE:
+        puts("ERROR: Socket listen: EADDRINUSE");
+        break;
+      case EBADF:
+        puts("ERROR: Socket listen: EBADF");
+        break;
+      case ENOTSOCK:
+        puts("ERROR: Socket listen: ENOTSOCK");
+        break;
+      default:
+        puts("ERROR: Socket listen: Unknown Error");
+        break;
+    }
+
+    return -1;
+  }
+}
+
+void cleanup_tcp_socket(int *tcp_socket) {
+  if (tcp_socket && *tcp_socket != -1) {
+    close(*tcp_socket);
+    *tcp_socket = -1;
+  }
+}
+
+void print_usage(void) {
+  puts("Usage:");
+  puts("  -p <port> | --port <port>");
+}
+
+Args parse_args(int argc, char **argv) {
+  --argc;
+  ++argv;
+
+  Args args;
+  memset(&args, 0, sizeof(Args));
+
+  while (argc > 0) {
+    if ((strcmp(argv[0], "-p") == 0 || strcmp(argv[0], "--port") == 0)
+        && argc > 1) {
+      int value = atoi(argv[1]);
+      if (value >= 0 && value <= 0xFFFF) {
+        args.port = (unsigned short) value;
+      }
+      --argc;
+      ++argv;
+    } else {
+      puts("ERROR: Invalid args!\n");
+      print_usage();
+      exit(1);
+    }
+
+    --argc;
+    ++argv;
+  }
+
+  return args;
+}
+
 int main(int argc, char **argv) {
+  Args args = parse_args(argc, argv);
+
+  printf("%u\n", args.port);
+
+  __attribute__((cleanup(cleanup_tcp_socket))) int tcp_socket = create_tcp_socket(args.port);
+
+  struct timespec sleep_time;
+  sleep_time.tv_sec = 0;
+  sleep_time.tv_nsec = C_SIMPLE_HTTP_SLEEP_NANOS;
+  signal(SIGINT, C_SIMPLE_HTTP_handle_sigint);
+  while (C_SIMPLE_HTTP_KEEP_RUNNING) {
+    nanosleep(&sleep_time, NULL);
+#ifndef NDEBUG
+    printf(".");
+    fflush(stdout);
+#endif
+  }
+
+  printf("End of program.\n");
   return 0;
 }