Created
March 4, 2018 10:26
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echo_deadlock.c
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#include <stdio.h> | |
#include <stdlib.h> | |
#include <sys/types.h> | |
#include <sys/socket.h> | |
#include <netinet/in.h> | |
#include <linux/netfilter_ipv4.h> | |
#include <unistd.h> | |
#define BUFFER_SIZE 1024 | |
#define on_error(...) { fprintf(stderr, __VA_ARGS__); fflush(stderr); exit(1); } | |
int main (int argc, char *argv[]) { | |
if (argc < 2) on_error("Usage: %s [port]\n", argv[0]); | |
int port = atoi(argv[1]); | |
int server_fd, client_fd, err; | |
struct sockaddr_in server, client; | |
char buf[BUFFER_SIZE]; | |
server_fd = socket(AF_INET, SOCK_STREAM, 0); | |
if (server_fd < 0) on_error("Could not create socket\n"); | |
server.sin_family = AF_INET; | |
server.sin_port = htons(port); | |
server.sin_addr.s_addr = htonl(INADDR_ANY); | |
int opt_val = 1; | |
setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt_val, sizeof opt_val); | |
err = bind(server_fd, (struct sockaddr *) &server, sizeof(server)); | |
if (err < 0) on_error("Could not bind socket\n"); | |
err = listen(server_fd, 128); | |
if (err < 0) on_error("Could not listen on socket\n"); | |
printf("Server is listening on %d\n", port); | |
while (1) { | |
socklen_t client_len = sizeof(client); | |
client_fd = accept(server_fd, (struct sockaddr *) &client, &client_len); | |
/* BUG BUG BUG */ | |
struct sockaddr_storage dst; | |
int s = sizeof(dst); | |
int error = getsockopt(client_fd, SOL_IP, SO_ORIGINAL_DST, &dst, &s); | |
if (error) { | |
return 1; | |
} | |
/* BUG BUG BUG */ | |
if (client_fd < 0) on_error("Could not establish new connection\n"); | |
while (1) { | |
int read = recv(client_fd, buf, BUFFER_SIZE, 0); | |
if (!read) break; // done reading | |
if (read < 0) on_error("Client read failed\n"); | |
err = send(client_fd, buf, read, 0); | |
if (err < 0) on_error("Client write failed\n"); | |
} | |
} | |
return 0; | |
} |
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