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#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <errno.h>
#include <limits.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "proxy.h"
static int parse_host(const char *host, const char *port, struct addrinfo **addr)
{
struct addrinfo hints = {
.ai_family = AF_UNSPEC,
.ai_socktype = SOCK_STREAM,
.ai_flags = AI_PASSIVE,
};
int err;
if ((err = getaddrinfo(host, port, &hints, addr))) {
fprintf(stderr, "getaddrinfo failed: %s\n", gai_strerror(err));
return -1;
}
return 0;
}
static int listen_source(struct addrinfo *source)
{
int fd = -1;
for (struct addrinfo *a = source; a; a = a->ai_next) {
if ((fd = socket(a->ai_family, a->ai_socktype, a->ai_protocol)) == -1)
continue;
if (!bind(fd, a->ai_addr, a->ai_addrlen) && !listen(fd, 1))
break;
close(fd);
fd = -1;
}
return fd;
}
static int connect_target(struct addrinfo *target)
{
int fd = -1;
for (struct addrinfo *a = target; a; a = a->ai_next) {
if ((fd = socket(a->ai_family, a->ai_socktype, a->ai_protocol)) == -1)
continue;
if (connect(fd, a->ai_addr, a->ai_addrlen) != -1)
break;
close(fd);
fd = -1;
}
return fd;
}
struct args {
struct addrinfo *source;
struct addrinfo *target;
unsigned delay;
};
static void usage(const char *progname)
{
int width = 20;
const char *args[] = {
"-d DELAY", "millisecond delay to add (default: 500ms)",
"-p LOCALPORT", "port to listen on (default: 1234)",
NULL
};
fprintf(stderr, "usage: %s [-d DELAY] [-p LOCALPORT] HOST PORT\n\n", progname);
for (const char **a = args; *a; a += 2)
fprintf(stderr, "\t%-*s %s\n", width, a[0], a[1]);
}
static int parse_unsigned(const char *arg, unsigned *out)
{
char *end;
errno = 0;
unsigned long val = strtoul(arg, &end, 10);
if (*end) return -1;
if (errno && !val) return -1;
if (val == ULONG_MAX && errno == ERANGE) return -1;
if (val > UINT_MAX) return -1;
*out = val;
return 0;
}
static int parse_args(struct args *args, int argc, char **argv)
{
args->delay = 500;
const char *localport = "1234";
const char *host = NULL, *port = NULL;
extern char *optarg;
extern int optind;
int opt, error = 0;
while ((opt = getopt(argc, argv, "+d:p:")) != -1) {
switch (opt) {
case 'd':
if (parse_unsigned(optarg, &args->delay)) {
fprintf(stderr, "invalid delay\n");
error = 1;
}
break;
case 'p':
localport = optarg;
break;
default:
error = 1;
}
}
if (optind <= argc - 2) {
host = argv[optind++];
port = argv[optind++];
} else error = 1;
if (error) {
usage(argv[0]);
return -1;
}
if (parse_host(NULL, localport, &args->source))
return -1;
if (parse_host(host, port, &args->target))
return -1;
return 0;
}
int main(int argc, char **argv)
{
struct args args;
if (parse_args(&args, argc, argv))
return -1;
int listenfd = listen_source(args.source);
if (listenfd < 0) {
perror("listen_source");
return -1;
}
for (;;) {
int sourcefd = accept(listenfd, NULL, NULL);
if (sourcefd == -1) break;
int targetfd = connect_target(args.target);
if (targetfd == -1) {
perror("connect_target");
close(sourcefd);
break;
}
proxy(sourcefd, targetfd, args.delay);
close(targetfd);
close(sourcefd);
}
close(listenfd);
return 0;
}
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