wrote socksv5 proxy

client/socks5proxy.c

@@ -0,0 +1,302 @@
+/** SOCKSv5 proxy that listens on port 1080.
+ *
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <netdb.h>
+
+int proxy_data(int sockfd);
+
+int main(void){
+	int listen_socket;
+	
+	struct sockaddr_in address;
+	struct sockaddr_in remote_addr;
+	socklen_t addr_size;
+	if (!(listen_socket = socket(AF_INET, SOCK_STREAM, 0))){
+		printf("Error creating socket\n");
+		return 1;
+	}
+
+	address.sin_family = AF_INET;
+	address.sin_addr.s_addr = INADDR_ANY;
+	address.sin_port = htons(1080);
+
+	if(bind(listen_socket, (struct sockaddr *) &address, sizeof(address))){
+		printf("Error binding socket\n");
+		return 1;
+	}
+
+	if(listen(listen_socket, 10) < 0){
+		printf("Error listening\n");
+		close(listen_socket);
+		exit(1);
+	}
+
+	for(;;){
+		addr_size = sizeof(remote_addr);
+		int new_socket;
+		new_socket = accept(listen_socket, (struct sockaddr *) &remote_addr,
+						&addr_size);
+		if(new_socket < 0){
+			perror("accept");
+			exit(1);
+		}
+
+		int pid = fork();
+		if(pid > 0){ //child
+
+			close(listen_socket);
+			proxy_data(new_socket);
+			exit(0);
+		}
+
+		close(new_socket);
+
+		
+	}
+
+	return 0;
+}
+
+struct socks_method_req {
+	uint8_t version;
+	uint8_t num_methods;
+};
+
+struct socks_req {
+	uint8_t version;
+	uint8_t cmd;
+	uint8_t rsvd;
+	uint8_t addr_type;
+};
+
+//continuously read from the socket and look for a CONNECT message
+int proxy_data(int sockfd){
+	uint8_t *buffer = calloc(1, BUFSIZ);
+	uint8_t *response = calloc(1, BUFSIZ);
+	
+	int bytes_read = recv(sockfd, buffer, BUFSIZ-1, 0);
+	if (bytes_read < 0){
+		printf("Error reading from socket\n");
+		goto err;
+	}
+
+	printf("Received %d bytes:\n", bytes_read);
+	for(int i=0; i< bytes_read; i++){
+		printf("%02x ", buffer[i]);
+	}
+	printf("\n");
+
+	//Respond to methods negotiation
+	struct socks_method_req *clnt_meth = (struct socks_method_req *) buffer;
+	uint8_t *p = buffer + 2;
+
+	if(clnt_meth->version != 0x05){
+		printf("Client supplied invalid version: %02x\n", clnt_meth->version);
+	}
+
+	int responded = 0;
+	int bytes_sent;
+	for(int i=0; i< clnt_meth->num_methods; i++){
+		if(p[0] == 0x00){//send response with METH= 0x00
+			response[0] = 0x05;
+			response[1] = 0x00;
+			send(sockfd, response, 2, 0);
+			responded = 1;
+		}
+		p++;
+	}
+	if(!responded){//respond with METH= 0xFF
+		response[0] = 0x05;
+		response[1] = 0xFF;
+		send(sockfd, response, 2, 0);
+		goto err;
+	}
+
+	//Now wait for a connect request
+	bytes_read = recv(sockfd, buffer, BUFSIZ-1, 0);
+	if (bytes_read < 0){
+		printf("Error reading from socket\n");
+		goto err;
+	}
+
+	printf("Received %d bytes:\n", bytes_read);
+	for(int i=0; i< bytes_read; i++){
+		printf("%02x ", buffer[i]);
+	}
+	printf("\n");
+
+
+	struct socks_req *clnt_req = (struct socks_req *) buffer;
+	p = buffer+4;
+
+	//see if it's a connect request
+	if(clnt_req->cmd != 0x01){
+		printf("Error: issued a non-connect command\n");
+		goto err;
+	}
+
+	//from this point on, this code will live on slitheen relay
+
+    struct sockaddr_in dest;
+	dest.sin_family = AF_INET;
+	uint8_t domain_len;
+
+	switch(clnt_req->addr_type){
+	case 0x01:
+		//IPv4
+		dest.sin_addr.s_addr = *((uint32_t*) p);
+		printf("destination addr: %d\n", ntohl(dest.sin_addr.s_addr));
+		p += 4;
+		break;
+		
+	case 0x03:
+		//domain name
+		domain_len = p[0];
+		p++;
+		uint8_t *domain_name = calloc(1, domain_len+1);
+		memcpy(domain_name, p, domain_len);
+		domain_name[domain_len] = '\0';
+		struct hostent *host;
+		host = gethostbyname((const char *) domain_name);
+		dest.sin_addr = *((struct in_addr *) host->h_addr);
+		printf("destination addr: %d\n", ntohl(dest.sin_addr.s_addr));
+
+		p += domain_len;
+		free(domain_name);
+		break;
+	case 0x04:
+		//IPv6
+		goto err;//TODO: fix this
+		break;
+	}
+
+	//now set the port
+	dest.sin_port = *((uint16_t *) p);
+	printf("destination port: %d\n", ntohs(dest.sin_port));
+
+    int32_t handle = socket(AF_INET, SOCK_STREAM, 0);
+    if(handle < 0){
+        printf("error: constructing socket failed\n");
+		goto err;
+    }
+
+	struct sockaddr_in my_addr;
+	socklen_t my_addr_len = sizeof(my_addr);
+
+    int32_t error = connect (handle, (struct sockaddr *) &dest, sizeof (struct sockaddr));
+
+    if(error <0){
+        printf("error connecting\n");
+		goto err;
+    }
+
+	getsockname(handle, (struct sockaddr *) &my_addr, &my_addr_len);
+
+	//now send the reply to the client
+	response[0] = 0x05;
+	response[1] = 0x00;//TODO: make this accurate
+	response[2] = 0x00;
+	response[3] = 0x01;
+	*((uint32_t *) (response + 4)) = my_addr.sin_addr.s_addr;
+	*((uint16_t *) (response + 8)) = my_addr.sin_port;
+
+	printf("Bound to %x:%d\n", my_addr.sin_addr.s_addr, ntohs(my_addr.sin_port));
+
+	bytes_sent = send(sockfd, response, 10,0);
+	printf("Sent response (%d bytes):\n", bytes_sent);
+	for(int i=0; i< bytes_sent; i++){
+		printf("%02x ", response[i]);
+	}
+	printf("\n");
+
+	//now shuffle data
+
+	for(;;){
+
+		fd_set readfds;
+		fd_set writefds;
+
+		int32_t nfds = (sockfd > handle) ? sockfd +1 : handle + 1;
+
+		FD_ZERO(&readfds);
+		FD_ZERO(&writefds);
+
+		FD_SET(sockfd, &readfds);
+		FD_SET(handle, &readfds);
+		FD_SET(sockfd, &writefds);
+		FD_SET(handle, &writefds);
+
+		if(select(nfds, &readfds, &writefds, NULL, NULL) <0){
+			printf("Select error\n");
+			continue;
+		}
+
+		if(FD_ISSET(sockfd, &readfds) && FD_ISSET(handle, &writefds)){
+
+			bytes_read = recv(sockfd, buffer, BUFSIZ-1, 0);
+			if (bytes_read < 0){
+				printf("Error reading from socket\n");
+				goto err;
+			}
+
+			if(bytes_read > 0){
+
+				printf("Received %d bytes:\n", bytes_read);
+				for(int i=0; i< bytes_read; i++){
+					printf("%02x ", buffer[i]);
+				}
+				printf("\n");
+
+				bytes_sent = send(handle, buffer, bytes_read, 0);
+				printf("Sent to website (%d bytes):\n", bytes_sent);
+				for(int i=0; i< bytes_sent; i++){
+					printf("%02x ", buffer[i]);
+				}
+				printf("\n");
+
+			}
+		} else if(FD_ISSET(handle, &readfds) && FD_ISSET(sockfd, &writefds)){
+
+			bytes_read = recv(handle, buffer, BUFSIZ-1, 0);
+			if (bytes_read < 0){
+				printf("Error reading from socket\n");
+				goto err;
+			}
+
+			if(bytes_read > 0){
+
+				printf("Received %d bytes:\n", bytes_read);
+				for(int i=0; i< bytes_read; i++){
+					printf("%02x ", buffer[i]);
+				}
+				printf("\n");
+
+				bytes_sent = send(sockfd, buffer, bytes_read, 0);
+				printf("Sent to website (%d bytes):\n", bytes_sent);
+				for(int i=0; i< bytes_sent; i++){
+					printf("%02x ", buffer[i]);
+				}
+				printf("\n");
+
+			}
+		}
+	}
+
+
+err:
+	close(sockfd);
+	free(buffer);
+	free(response);
+	exit(0);
+}