From 5664bba1f343fb2f987d136527ffc742afc76f7e Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Wed, 18 Nov 2020 15:43:27 +0530
Subject: add q7: remote command executor

---
 q7/server.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 q7/server.c

(limited to 'q7/server.c')

diff --git a/q7/server.c b/q7/server.c
new file mode 100644
index 0000000..12df5bb
--- /dev/null
+++ b/q7/server.c
@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <wait.h>
+
+int main(int argc, char *argv[]) {
+    int sockfd, connfd; 
+    struct sockaddr_in servaddr, cli; 
+  
+    sockfd = socket(AF_INET, SOCK_STREAM, 0); 
+    servaddr.sin_family = AF_INET; 
+    servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 
+
+    int port = atoi(argv[1]);
+    servaddr.sin_port = htons(port);
+  
+    bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
+  
+    listen(sockfd, 128);
+    printf("Server started at %s...\n", inet_ntoa(servaddr.sin_addr));
+    fflush(stdout);
+
+    while(1) {
+        socklen_t len = sizeof(cli);
+        connfd = accept(sockfd, (struct sockaddr *)&cli, &len);
+        int i = getpeername(connfd, (struct sockaddr*)&cli, &len);
+
+        printf("Client connected at port %d\n", htons(cli.sin_port));
+        int n;
+        char buf[100];
+        int pid;
+
+        if((pid=fork())==0){
+            close(sockfd);
+            while((n = recv(connfd, buf, 100, 0)) > 0) {
+                printf("Client message: %s\n", buf);
+                int pipes[2];
+                pipe(&pipes[0]);
+                if ((pid=fork()) == 0) {
+                    dup2(pipes[1], STDOUT_FILENO);
+                    close(pipes[0]);
+                    execl("/bin/sh", "sh", "-c", buf, (char *) NULL);
+                } else {
+                    close(pipes[1]);
+                    char cmd_output[1024];
+                    int cmd_size = read(pipes[0], cmd_output, sizeof(cmd_output));
+                    send(connfd, cmd_output, cmd_size, 0);
+                    wait(NULL);
+                }
+                fflush(stdout);
+            };
+            exit(0);
+        }
+        close(connfd);
+    }
+    return 0;
+}
-- 
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