From 0107291f780228edd3bae34cca59974a5734feda Mon Sep 17 00:00:00 2001
From: Mikhail Burakov <mburakov@mailbox.org>
Date: Sun, 2 Apr 2023 20:44:29 +0200
Subject: Connect to socket instead of reading stdin

---
 main.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 54 insertions(+), 4 deletions(-)

(limited to 'main.c')

diff --git a/main.c b/main.c
index bc8c736..ec05612 100644
--- a/main.c
+++ b/main.c
@@ -15,10 +15,14 @@
  * along with receiver.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+#include <arpa/inet.h>
 #include <errno.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
 #include <poll.h>
 #include <signal.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -31,6 +35,48 @@
 static volatile sig_atomic_t g_signal;
 static void OnSignal(int status) { g_signal = status; }
 
+static void SocketDtor(int* sock) {
+  if (*sock == -1) return;
+  close(*sock);
+  *sock = -1;
+}
+
+static int ConnectSocket(const char* arg) {
+  uint16_t port;
+  char ip[sizeof("xxx.xxx.xxx.xxx")];
+  if (sscanf(arg, "%[0-9.]:%hu", ip, &port) != 2) {
+    LOG("Failed to parse address");
+    return -1;
+  }
+
+  int sock = socket(AF_INET, SOCK_STREAM, 0);
+  if (sock == -1) {
+    LOG("Failed to create socket (%s)", strerror(errno));
+    return -1;
+  }
+  static const int one = 1;
+  if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one))) {
+    LOG("Failed to set TCP_NODELAY (%s)", strerror(errno));
+    goto rollback_sock;
+  }
+
+  // TODO(mburakov): Set and maintain TCP_QUICKACK.
+  const struct sockaddr_in addr = {
+      .sin_family = AF_INET,
+      .sin_port = htons(port),
+      .sin_addr.s_addr = inet_addr(ip),
+  };
+  if (connect(sock, (const struct sockaddr*)&addr, sizeof(addr))) {
+    LOG("Failed to connect socket (%s)", strerror(errno));
+    goto rollback_sock;
+  }
+  return sock;
+
+rollback_sock:
+  close(sock);
+  return -1;
+}
+
 static void OnWindowClose(void* user) {
   (void)user;
   g_signal = SIGINT;
@@ -53,8 +99,12 @@ static void DecodeContextDtor(struct DecodeContext** decode_context) {
 }
 
 int main(int argc, char* argv[]) {
-  (void)argc;
-  (void)argv;
+  if (argc < 2) {
+    LOG("Usage: %s <ip>:<port>", argv[0]);
+    return EXIT_FAILURE;
+  }
+  int __attribute__((cleanup(SocketDtor))) sock = ConnectSocket(argv[1]);
+  if (sock == -1) return EXIT_FAILURE;
 
   static const struct WindowEventHandlers window_event_handlers = {
       .OnClose = OnWindowClose,
@@ -89,7 +139,7 @@ int main(int argc, char* argv[]) {
 
   while (!g_signal) {
     struct pollfd pfds[] = {
-        {.fd = STDIN_FILENO, .events = POLLIN},
+        {.fd = sock, .events = POLLIN},
         {.fd = events_fd, .events = POLLIN},
     };
     switch (poll(pfds, LENGTH(pfds), -1)) {
@@ -104,7 +154,7 @@ int main(int argc, char* argv[]) {
       default:
         break;
     }
-    if (pfds[0].revents && !DecodeContextDecode(decode_context, STDIN_FILENO)) {
+    if (pfds[0].revents && !DecodeContextDecode(decode_context, sock)) {
       LOG("Failed to decode incoming data");
       return EXIT_FAILURE;
     }
-- 
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