chat

commit 385af01b7ea5b08bc7d03841c17b156afaa9401f
Author: evenfri <evenfri256@gmail.com>
Date:   Fri, 28 Aug 2026 00:46:38 +0800

initial commit

Diffstat:
A
.gitignore
 | 
3
+++
A
build.sh
 | 
21
+++++++++++++++++++++
A
client.c
 | 
127
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
server.c
 | 
150
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

4 files changed, 301 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,3 @@
+*.o
+server
+client
diff --git a/build.sh b/build.sh
@@ -0,0 +1,21 @@
+#!/bin/sh
+
+cflags="-Wall -Wextra"
+
+set -e
+
+compile() {
+  f="$1"
+
+  echo "cc $f"
+  gcc -c $cflags $f
+}
+
+compile server.c
+compile client.c
+
+echo "ld server"
+gcc -o server server.o
+
+echo "ld client"
+gcc -o client client.o
diff --git a/client.c b/client.c
@@ -0,0 +1,127 @@
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <poll.h>
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#define BUFFER_SIZE 1024
+
+int main(int argc, char *argv[]) {
+  int fd;
+  int n;
+  int result;
+  int message_size;
+  struct sockaddr_in addr;
+  struct pollfd fds[2];
+  char buffer[BUFFER_SIZE];
+  char message[BUFFER_SIZE];
+  char *nickname;
+
+  if (argc > 1) {
+    nickname = argv[1];
+  } else {
+    nickname = "Client";
+  }
+
+  fd = socket(AF_INET, SOCK_STREAM, 0);
+  if (fd == -1) {
+    perror("socket");
+    return 1;
+  }
+
+  memset(&addr, 0, sizeof(addr));
+
+  addr.sin_family = AF_INET;
+  addr.sin_port = htons(8080);
+
+  if (inet_pton(AF_INET, "127.0.0.1", &addr.sin_addr) != 1) {
+    fprintf(stderr, "invalid address\n");
+    close(fd);
+    return 1;
+  }
+
+  if (connect(fd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
+    perror("connect");
+    close(fd);
+    return 1;
+  }
+
+  printf("connected\n");
+  printf("> ");
+  fflush(stdout);
+
+  fds[0].fd = fd;
+  fds[0].events = POLLIN;
+
+  fds[1].fd = STDIN_FILENO;
+  fds[1].events = POLLIN;
+
+  while (1) {
+    result = poll(fds, 2, -1);
+
+    if (result == -1) {
+      perror("poll");
+      break;
+    }
+
+    /*
+     * Server sent something.
+     */
+    if (fds[0].revents & POLLIN) {
+      n = recv(fd, buffer, sizeof(buffer) - 1, 0);
+
+      if (n == -1) {
+        perror("recv");
+        break;
+      }
+
+      if (n == 0) {
+        printf("\nserver disconnected\n");
+        break;
+      }
+
+      buffer[n] = '\0';
+
+      printf("\r%s", buffer);
+      printf("> ");
+      fflush(stdout);
+    }
+
+    /*
+     * User typed something.
+     */
+    if (fds[1].revents & POLLIN) {
+      if (fgets(buffer, sizeof(buffer), stdin) == NULL) {
+        break;
+      }
+
+      message_size = snprintf(
+        message,
+        sizeof(message),
+        "%s: %s",
+        nickname,
+        buffer
+      );
+
+      if (message_size < 0 || message_size >= (int)sizeof(message)) {
+        fprintf(stderr, "message too long\n");
+        continue;
+      }
+
+      if (send(fd, message, message_size, 0) == -1) {
+        perror("send");
+        break;
+      }
+
+      printf("> ");
+      fflush(stdout);
+    }
+  }
+
+  close(fd);
+
+  return 0;
+}
diff --git a/server.c b/server.c
@@ -0,0 +1,150 @@
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <poll.h>
+
+#include <sys/socket.h>
+#include <netinet/in.h>
+
+#define MAX_CLIENTS 16
+#define BUFFER_SIZE 1024
+
+int main() {
+  int server_fd;
+  int client_fd;
+  int client_count;
+  int i;
+  int j;
+  int n;
+  int result;
+  struct sockaddr_in addr;
+  struct pollfd fds[MAX_CLIENTS + 1];
+  char buffer[BUFFER_SIZE];
+
+  server_fd = socket(AF_INET, SOCK_STREAM, 0);
+  if (server_fd == -1) {
+    perror("socket");
+    return 1;
+  }
+
+  memset(&addr, 0, sizeof(addr));
+
+  addr.sin_family = AF_INET;
+  addr.sin_port = htons(8080);
+  addr.sin_addr.s_addr = htonl(INADDR_ANY);
+
+  if (bind(server_fd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
+    perror("bind");
+    close(server_fd);
+    return 1;
+  }
+
+  if (listen(server_fd, 16) == -1) {
+    perror("listen");
+    close(server_fd);
+    return 1;
+  }
+
+  memset(fds, 0, sizeof(fds));
+
+  fds[0].fd = server_fd;
+  fds[0].events = POLLIN;
+
+  client_count = 0;
+
+  printf("listening on port 8080\n");
+
+  while (1) {
+    result = poll(fds, client_count + 1, -1);
+
+    if (result == -1) {
+      perror("poll");
+      break;
+    }
+
+    /*
+     * New client.
+     */
+    if (fds[0].revents & POLLIN) {
+      client_fd = accept(server_fd, NULL, NULL);
+
+      if (client_fd == -1) {
+        perror("accept");
+      } else if (client_count >= MAX_CLIENTS) {
+        printf("too many clients\n");
+        close(client_fd);
+      } else {
+        client_count++;
+
+        fds[client_count].fd = client_fd;
+        fds[client_count].events = POLLIN;
+
+        printf("client %d connected\n", client_fd);
+      }
+    }
+
+    /*
+     * Existing clients.
+     */
+    for (i = 1; i <= client_count; i++) {
+      if (!(fds[i].revents & POLLIN)) {
+        continue;
+      }
+
+      n = recv(fds[i].fd, buffer, sizeof(buffer), 0);
+
+      if (n == -1) {
+        perror("recv");
+
+        close(fds[i].fd);
+
+        for (j = i; j < client_count; j++) {
+          fds[j] = fds[j + 1];
+        }
+
+        client_count--;
+        i--;
+
+        continue;
+      }
+
+      if (n == 0) {
+        printf("client %d disconnected\n", fds[i].fd);
+
+        close(fds[i].fd);
+
+        for (j = i; j < client_count; j++) {
+          fds[j] = fds[j + 1];
+        }
+
+        client_count--;
+        i--;
+
+        continue;
+      }
+
+      /*
+       * Broadcast.
+       */
+      printf("client %d sent %d bytes\n", fds[i].fd, n);
+
+      for (j = 1; j <= client_count; j++) {
+        if (j == i) {
+          continue;
+        }
+
+        if (send(fds[j].fd, buffer, n, 0) == -1) {
+          perror("send");
+        }
+      }
+    }
+  }
+
+  for (i = 1; i <= client_count; i++) {
+    close(fds[i].fd);
+  }
+
+  close(server_fd);
+
+  return 0;
+}