contrib: add sticky sockets example code
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld
parent
92feabdd17
commit
6c7d67acfe
5
contrib/sticky-sockets/README
Normal file
5
contrib/sticky-sockets/README
Normal file
@ -0,0 +1,5 @@
|
||||
Sticky Sockets
|
||||
==============
|
||||
|
||||
This is a small userspace mini-library that implements as close to
|
||||
possible how the kernel does its sticky src address sending.
|
||||
BIN
contrib/sticky-sockets/a.out
Executable file
BIN
contrib/sticky-sockets/a.out
Executable file
Binary file not shown.
337
contrib/sticky-sockets/sticky-sockets.c
Normal file
337
contrib/sticky-sockets/sticky-sockets.c
Normal file
@ -0,0 +1,337 @@
|
||||
/* Copyright 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
|
||||
*
|
||||
* This implements userspace semantics of "sticky sockets", modeled after
|
||||
* WireGuard's kernelspace implementation.
|
||||
*/
|
||||
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <stdint.h>
|
||||
#include <string.h>
|
||||
#include <errno.h>
|
||||
#include <unistd.h>
|
||||
#include <linux/ipv6.h>
|
||||
#include <sys/socket.h>
|
||||
#include <netinet/in.h>
|
||||
#include <netinet/udp.h>
|
||||
#include <arpa/inet.h>
|
||||
|
||||
struct magic_endpoint {
|
||||
union {
|
||||
struct sockaddr addr;
|
||||
struct sockaddr_in addr4;
|
||||
struct sockaddr_in6 addr6;
|
||||
};
|
||||
union {
|
||||
struct {
|
||||
struct in_addr src4;
|
||||
int src_if4; /* Essentially the same as addr6->scope_id */
|
||||
};
|
||||
struct in6_addr src6;
|
||||
};
|
||||
};
|
||||
|
||||
ssize_t magic_send4(int sock, struct magic_endpoint *endpoint, void *buffer, size_t len)
|
||||
{
|
||||
ssize_t ret;
|
||||
struct iovec iovec = {
|
||||
.iov_base = buffer,
|
||||
.iov_len = len
|
||||
};
|
||||
struct {
|
||||
struct cmsghdr cmsghdr;
|
||||
struct in_pktinfo pktinfo;
|
||||
} cmsg = {
|
||||
.cmsghdr.cmsg_level = IPPROTO_IP,
|
||||
.cmsghdr.cmsg_type = IP_PKTINFO,
|
||||
.cmsghdr.cmsg_len = CMSG_LEN(sizeof(cmsg.pktinfo)),
|
||||
.pktinfo.ipi_spec_dst = endpoint->src4,
|
||||
.pktinfo.ipi_ifindex = endpoint->src_if4
|
||||
};
|
||||
struct msghdr msghdr = {
|
||||
.msg_iov = &iovec,
|
||||
.msg_iovlen = 1,
|
||||
.msg_name = &endpoint->addr4,
|
||||
.msg_namelen = sizeof(endpoint->addr4),
|
||||
.msg_control = &cmsg,
|
||||
.msg_controllen = sizeof(cmsg)
|
||||
};
|
||||
ret = sendmsg(sock, &msghdr, 0);
|
||||
if (ret < 0 && errno == EINVAL) {
|
||||
memset(&cmsg.pktinfo, 0, sizeof(cmsg.pktinfo));
|
||||
endpoint->src4.s_addr = endpoint->src_if4 = 0;
|
||||
return sendmsg(sock, &msghdr, 0);
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
ssize_t magic_send6(int sock, struct magic_endpoint *endpoint, void *buffer, size_t len)
|
||||
{
|
||||
ssize_t ret;
|
||||
struct iovec iovec = {
|
||||
.iov_base = buffer,
|
||||
.iov_len = len
|
||||
};
|
||||
struct {
|
||||
struct cmsghdr cmsghdr;
|
||||
struct in6_pktinfo pktinfo;
|
||||
} cmsg = {
|
||||
.cmsghdr.cmsg_level = IPPROTO_IPV6,
|
||||
.cmsghdr.cmsg_type = IPV6_PKTINFO,
|
||||
.cmsghdr.cmsg_len = CMSG_LEN(sizeof(cmsg.pktinfo)),
|
||||
.pktinfo.ipi6_addr = endpoint->src6,
|
||||
.pktinfo.ipi6_ifindex = memcmp(&in6addr_any, &endpoint->src6, sizeof(endpoint->src6)) ? endpoint->addr6.sin6_scope_id : 0
|
||||
};
|
||||
struct msghdr msghdr = {
|
||||
.msg_iov = &iovec,
|
||||
.msg_iovlen = 1,
|
||||
.msg_name = &endpoint->addr6,
|
||||
.msg_namelen = sizeof(endpoint->addr6),
|
||||
.msg_control = &cmsg,
|
||||
.msg_controllen = sizeof(cmsg)
|
||||
};
|
||||
|
||||
ret = sendmsg(sock, &msghdr, 0);
|
||||
if (ret < 0 && errno == EINVAL) {
|
||||
memset(&cmsg.pktinfo, 0, sizeof(cmsg.pktinfo));
|
||||
memset(&endpoint->src6, 0, sizeof(endpoint->src6));
|
||||
return sendmsg(sock, &msghdr, 0);
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
ssize_t magic_receive4(int sock, struct magic_endpoint *endpoint, void *buffer, size_t len)
|
||||
{
|
||||
ssize_t ret;
|
||||
struct iovec iovec = {
|
||||
.iov_base = buffer,
|
||||
.iov_len = len
|
||||
};
|
||||
struct {
|
||||
struct cmsghdr cmsghdr;
|
||||
struct in_pktinfo pktinfo;
|
||||
} cmsg;
|
||||
struct msghdr msghdr = {
|
||||
.msg_iov = &iovec,
|
||||
.msg_iovlen = 1,
|
||||
.msg_name = &endpoint->addr4,
|
||||
.msg_namelen = sizeof(endpoint->addr4),
|
||||
.msg_control = &cmsg,
|
||||
.msg_controllen = sizeof(cmsg)
|
||||
};
|
||||
|
||||
ret = recvmsg(sock, &msghdr, 0);
|
||||
if (ret < 0)
|
||||
return ret;
|
||||
if (cmsg.cmsghdr.cmsg_level == IPPROTO_IP && cmsg.cmsghdr.cmsg_type == IP_PKTINFO && cmsg.cmsghdr.cmsg_len >= CMSG_LEN(sizeof(cmsg.pktinfo))) {
|
||||
endpoint->src4 = cmsg.pktinfo.ipi_spec_dst;
|
||||
endpoint->src_if4 = cmsg.pktinfo.ipi_ifindex;
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
ssize_t magic_receive6(int sock, struct magic_endpoint *endpoint, void *buffer, size_t len)
|
||||
{
|
||||
ssize_t ret;
|
||||
struct iovec iovec = {
|
||||
.iov_base = buffer,
|
||||
.iov_len = len
|
||||
};
|
||||
struct {
|
||||
struct cmsghdr cmsghdr;
|
||||
struct in6_pktinfo pktinfo;
|
||||
} cmsg;
|
||||
struct msghdr msghdr = {
|
||||
.msg_iov = &iovec,
|
||||
.msg_iovlen = 1,
|
||||
.msg_name = &endpoint->addr6,
|
||||
.msg_namelen = sizeof(endpoint->addr6),
|
||||
.msg_control = &cmsg,
|
||||
.msg_controllen = sizeof(cmsg)
|
||||
};
|
||||
|
||||
ret = recvmsg(sock, &msghdr, 0);
|
||||
if (ret < 0)
|
||||
return ret;
|
||||
if (cmsg.cmsghdr.cmsg_level == IPPROTO_IPV6 && cmsg.cmsghdr.cmsg_type == IPV6_PKTINFO && cmsg.cmsghdr.cmsg_len >= CMSG_LEN(sizeof(cmsg.pktinfo))) {
|
||||
endpoint->src6 = cmsg.pktinfo.ipi6_addr;
|
||||
endpoint->addr6.sin6_scope_id = cmsg.pktinfo.ipi6_ifindex;
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
void magic_endpoint_clearsrc(struct magic_endpoint *endpoint)
|
||||
{
|
||||
if (endpoint->addr.sa_family == AF_INET)
|
||||
endpoint->src4.s_addr = endpoint->src_if4 = 0;
|
||||
else if (endpoint->addr.sa_family == AF_INET6)
|
||||
memset(&endpoint->src6, 0, sizeof(endpoint->src6));
|
||||
else
|
||||
memset(endpoint, 0, sizeof(*endpoint));
|
||||
}
|
||||
|
||||
void magic_endpoint_set(struct magic_endpoint *endpoint, const struct sockaddr *addr)
|
||||
{
|
||||
if (addr->sa_family == AF_INET)
|
||||
endpoint->addr4 = *(struct sockaddr_in *)addr;
|
||||
else if (addr->sa_family == AF_INET6)
|
||||
endpoint->addr6 = *(struct sockaddr_in6 *)addr;
|
||||
magic_endpoint_clearsrc(endpoint);
|
||||
}
|
||||
|
||||
int magic_create_sock4(uint16_t listen_port)
|
||||
{
|
||||
static const int on = 1;
|
||||
struct sockaddr_in listen_addr = {
|
||||
.sin_family = AF_INET,
|
||||
.sin_port = htons(listen_port),
|
||||
.sin_addr = INADDR_ANY
|
||||
};
|
||||
int fd, ret;
|
||||
|
||||
fd = socket(AF_INET, SOCK_DGRAM, 0);
|
||||
if (fd < 0)
|
||||
return fd;
|
||||
|
||||
ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
|
||||
ret = setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
|
||||
ret = bind(fd, (struct sockaddr *)&listen_addr, sizeof(listen_addr));
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
|
||||
return fd;
|
||||
|
||||
err:
|
||||
close(fd);
|
||||
return ret;
|
||||
}
|
||||
|
||||
int magic_create_sock6(uint16_t listen_port)
|
||||
{
|
||||
static const int on = 1;
|
||||
struct sockaddr_in6 listen_addr = {
|
||||
.sin6_family = AF_INET6,
|
||||
.sin6_port = htons(listen_port),
|
||||
.sin6_addr = IN6ADDR_ANY_INIT
|
||||
};
|
||||
int fd, ret;
|
||||
|
||||
fd = socket(AF_INET6, SOCK_DGRAM, 0);
|
||||
if (fd < 0)
|
||||
return fd;
|
||||
|
||||
ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
|
||||
ret = setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &on, sizeof(on));
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
|
||||
ret = setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on));
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
|
||||
ret = bind(fd, (struct sockaddr *)&listen_addr, sizeof(listen_addr));
|
||||
if (ret < 0)
|
||||
goto err;
|
||||
|
||||
return fd;
|
||||
|
||||
err:
|
||||
close(fd);
|
||||
return ret;
|
||||
}
|
||||
|
||||
int main(int argc, char *argv[])
|
||||
{
|
||||
struct magic_endpoint endpoint = { 0 };
|
||||
int sock;
|
||||
ssize_t ret;
|
||||
uint8_t buffer[1024] = { 0 };
|
||||
char srcaddr[40], dstaddr[40];
|
||||
|
||||
if (argc == 2 && !strcmp(argv[1], "-4"))
|
||||
goto v4;
|
||||
if (argc == 2 && !strcmp(argv[1], "-6"))
|
||||
goto v6;
|
||||
return 1;
|
||||
|
||||
v6:
|
||||
sock = magic_create_sock6(51820);
|
||||
if (sock < 0) {
|
||||
perror("magic_create_sock6");
|
||||
return 1;
|
||||
}
|
||||
|
||||
ret = magic_receive6(sock, &endpoint, buffer, sizeof(buffer));
|
||||
if (ret < 0) {
|
||||
perror("magic_receive6");
|
||||
return 1;
|
||||
}
|
||||
|
||||
if (!inet_ntop(AF_INET6, &endpoint.src6, srcaddr, sizeof(srcaddr))) {
|
||||
perror("inet_ntop");
|
||||
return 1;
|
||||
}
|
||||
|
||||
if (!inet_ntop(AF_INET6, &endpoint.addr6.sin6_addr, dstaddr, sizeof(dstaddr))) {
|
||||
perror("inet_ntop");
|
||||
return 1;
|
||||
}
|
||||
|
||||
printf("if:%d src:%s dst:%s\n", endpoint.addr6.sin6_scope_id, srcaddr, dstaddr);
|
||||
printf("Received a packet. Sleeping for 10 seconds before replying, so you have time to mess with your networking setup.\n");
|
||||
sleep(10);
|
||||
|
||||
ret = magic_send6(sock, &endpoint, buffer, sizeof(buffer));
|
||||
if (ret < 0) {
|
||||
perror("magic_send6");
|
||||
return 1;
|
||||
}
|
||||
|
||||
close(sock);
|
||||
return 0;
|
||||
|
||||
v4:
|
||||
sock = magic_create_sock4(51820);
|
||||
if (sock < 0) {
|
||||
perror("magic_create_sock4");
|
||||
return 1;
|
||||
}
|
||||
|
||||
ret = magic_receive4(sock, &endpoint, buffer, sizeof(buffer));
|
||||
if (ret < 0) {
|
||||
perror("magic_receive4");
|
||||
return 1;
|
||||
}
|
||||
|
||||
if (!inet_ntop(AF_INET, &endpoint.src4, srcaddr, sizeof(srcaddr))) {
|
||||
perror("inet_ntop");
|
||||
return 1;
|
||||
}
|
||||
|
||||
if (!inet_ntop(AF_INET, &endpoint.addr4.sin_addr, dstaddr, sizeof(dstaddr))) {
|
||||
perror("inet_ntop");
|
||||
return 1;
|
||||
}
|
||||
|
||||
printf("if:%d src:%s dst:%s\n", endpoint.src_if4, srcaddr, dstaddr);
|
||||
printf("Received a packet. Sleeping for 10 seconds before replying, so you have time to mess with your networking setup.\n");
|
||||
sleep(10);
|
||||
|
||||
ret = magic_send4(sock, &endpoint, buffer, sizeof(buffer));
|
||||
if (ret < 0) {
|
||||
perror("magic_send4");
|
||||
return 1;
|
||||
}
|
||||
|
||||
close(sock);
|
||||
return 0;
|
||||
}
|
||||
Reference in New Issue
Block a user