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Added ipv6 support for command wrapping #624

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ee935d8
Added ipv6 support for wrapping (updated rebind.c)
CraftingDragon007 Nov 3, 2025
6962919
Updated unneeded else if queries to be just else
CraftingDragon007 Nov 4, 2025
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65 changes: 47 additions & 18 deletions rebind.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,9 @@
#include <dlfcn.h>

#include <string.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>


#if defined(DO_DEBUG)
Expand All @@ -37,25 +39,36 @@
#define DEBUG(...)
#endif


int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
{
static void * (*func)(int, const struct sockaddr *, socklen_t);
static int (*func)(int, const struct sockaddr *, socklen_t);
int do_move = 0;
struct sockaddr_in * addr_in = (struct sockaddr_in *)addr;
struct sockaddr_in addr_tmp;
struct sockaddr_storage addr_tmp;
socklen_t addrlen_tmp;
char * PORT_OLD, * PORT_NEW, * end1, * end2;
int ret, oldport, newport, askport = htons(addr_in->sin_port);
uint32_t askaddr = htons(addr_in->sin_addr.s_addr);
if (!func) func = (void *(*)(int, const struct sockaddr *, socklen_t)) dlsym(RTLD_NEXT, "bind");
int ret, oldport = 0, newport = 0, askport = 0;
char addr_str[INET6_ADDRSTRLEN] = "";
int family = addr ? addr->sa_family : AF_UNSPEC;

if (!func) {
func = (int (*)(int, const struct sockaddr *, socklen_t)) dlsym(RTLD_NEXT, "bind");
}

DEBUG(">> bind(%d, _, %d), askaddr %d, askport %d\n",
sockfd, addrlen, askaddr, askport);
if (family == AF_INET) {
const struct sockaddr_in *addr_in = (const struct sockaddr_in *)addr;
askport = ntohs(addr_in->sin_port);
inet_ntop(AF_INET, &addr_in->sin_addr, addr_str, sizeof(addr_str));
} else {
const struct sockaddr_in6 *addr_in6 = (const struct sockaddr_in6 *)addr;
askport = ntohs(addr_in6->sin6_port);
inet_ntop(AF_INET6, &addr_in6->sin6_addr, addr_str, sizeof(addr_str));
}

DEBUG(">> bind(%d, family %d, len %d), askaddr %s, askport %d\n",
sockfd, family, addrlen, addr_str, askport);

/* Determine if we should move this socket */
if (addr_in->sin_family == AF_INET) {
// TODO: support IPv6
if (family == AF_INET || family == AF_INET6) {
PORT_OLD = getenv("REBIND_OLD_PORT");
PORT_NEW = getenv("REBIND_NEW_PORT");
if (PORT_OLD && (*PORT_OLD != '\0') &&
Expand All @@ -72,22 +85,38 @@ int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen)

if (! do_move) {
/* Just pass everything right through to the real bind */
ret = (long) func(sockfd, addr, addrlen);
ret = func(sockfd, addr, addrlen);
DEBUG("<< bind(%d, _, %d) ret %d\n", sockfd, addrlen, ret);
return ret;
}

DEBUG("binding fd %d on localhost:%d instead of 0x%x:%d\n",
sockfd, newport, ntohl(addr_in->sin_addr.s_addr), oldport);
DEBUG("binding fd %d on localhost:%d instead of %s:%d\n",
sockfd, newport, addr_str[0] ? addr_str : "<unknown>", oldport);

/* Use a temporary location for the new address information */
addrlen_tmp = sizeof(addr_tmp);
addrlen_tmp = addrlen;
if (addrlen_tmp > sizeof(addr_tmp)) {
addrlen_tmp = sizeof(addr_tmp);
}
memcpy(&addr_tmp, addr, addrlen_tmp);

/* Bind to other port on the loopback instead */
addr_tmp.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
addr_tmp.sin_port = htons(newport);
ret = (long) func(sockfd, (const struct sockaddr *)&addr_tmp, addrlen_tmp);
if (family == AF_INET) {
struct sockaddr_in *addr_in_tmp = (struct sockaddr_in *)&addr_tmp;
addr_in_tmp->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
addr_in_tmp->sin_port = htons(newport);
} else {
struct sockaddr_in6 *addr_in6_tmp = (struct sockaddr_in6 *)&addr_tmp;
static const struct in6_addr v4_loopback_mapped = { // ::ffff:127.0.0.1
.s6_addr = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 127, 0, 0, 1}
};
int v6_only = 0;
(void)setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY, &v6_only, sizeof(v6_only));
addr_in6_tmp->sin6_addr = v4_loopback_mapped;
addr_in6_tmp->sin6_port = htons(newport);
addr_in6_tmp->sin6_scope_id = 0;
}
ret = func(sockfd, (const struct sockaddr *)&addr_tmp, addrlen_tmp);

DEBUG("<< bind(%d, _, %d) ret %d\n", sockfd, addrlen, ret);
return ret;
Expand Down