1 /*
2  * Copyright (c) 2026 Christoph Liebender <christoph@liebender.dev>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include "relayd.h"
18 
19 #define PROXY_V2_CMD_PROXY 0x01
20 
21 #define PROXY_V2_FAM_UNSPEC 0x00
22 #define PROXY_V2_FAM_TCP4   0x11
23 #define PROXY_V2_FAM_UDP4   0x12
24 #define PROXY_V2_FAM_TCP6   0x21
25 #define PROXY_V2_FAM_UDP6   0x22
26 
27 static const u_int8_t PROXY_V2_SIG[12] = {
28 	0x0D, 0x0A, 0x0D, 0x0A, 0x00, 0x0D, 0x0A, 0x51, 0x55, 0x49, 0x54, 0x0A
29 };
30 
31 struct proxy_v2_hdr {
32 	u_int8_t sig[12];
33 	u_int8_t ver_cmd;
34 	u_int8_t fam;
35 	u_int16_t len;
36 };
37 
38 union proxy_v2_addr {
39 	struct {
40 		u_int32_t src_addr;
41 		u_int32_t dst_addr;
42 		in_port_t src_port;
43 		in_port_t dst_port;
44 	} ipv4_addr;
45 	struct {
46 		u_int8_t  src_addr[16];
47 		u_int8_t  dst_addr[16];
48 		in_port_t src_port;
49 		in_port_t dst_port;
50 	} ipv6_addr;
51 };
52 
53 int
54 proxy_protocol_v1(struct rsession *con, struct evbuffer *dstout)
55 {
56 	char ibuf[128], obuf[128];
57 	const char *proxyproto;
58 	int ret;
59 
60 	bzero(&ibuf, sizeof(ibuf));
61 	bzero(&obuf, sizeof(obuf));
62 
63 	if (print_host(&con->se_in.ss, ibuf, sizeof(ibuf)) == NULL ||
64 	    print_host(&con->se_sockname, obuf, sizeof(obuf)) == NULL)
65 		return -1;
66 
67 	if (con->se_relay->rl_conf.flags & F_UDP)
68 		proxyproto = "UNKNOWN";
69 	else {
70 		switch (con->se_in.ss.ss_family) {
71 		case AF_INET:
72 			proxyproto = "TCP4";
73 			break;
74 		case AF_INET6:
75 			proxyproto = "TCP6";
76 			break;
77 		default:
78 			proxyproto = "UNKNOWN";
79 			break;
80 		}
81 	}
82 
83 	ret = evbuffer_add_printf(dstout,
84 		"PROXY %s %s %s %d %d\r\n", proxyproto, ibuf, obuf,
85 		ntohs(con->se_in.port), ntohs(con->se_relay->rl_conf.port));
86 
87 	return ret == -1 ? -1 : 0;
88 }
89 
90 int
91 proxy_protocol_v2(struct rsession *con, struct evbuffer *dstout)
92 {
93 	union proxy_v2_addr 	       addr;
94 	struct proxy_v2_hdr 	       hdr;
95 	const struct relay_config     *conf = &con->se_relay->rl_conf;
96 	const struct sockaddr_storage *srcss = &con->se_in.ss;
97 	const struct sockaddr_storage *dstss = &con->se_sockname;
98 	int 			       error;
99 	in_port_t		       srcport = con->se_in.port;
100 	in_port_t		       dstport = conf->port;
101 	u_int16_t 		       len;
102 
103 	bcopy(PROXY_V2_SIG, hdr.sig, sizeof(hdr.sig));
104 	hdr.ver_cmd = 0x20 | PROXY_V2_CMD_PROXY;
105 
106 	switch (dstss->ss_family) {
107 	case AF_INET:
108 		hdr.fam = (conf->flags & F_UDP) ?
109 			PROXY_V2_FAM_UDP4 : PROXY_V2_FAM_TCP4;
110 		len = sizeof(addr.ipv4_addr);
111 		addr.ipv4_addr.src_addr =
112 		    ((const struct sockaddr_in *)srcss)->sin_addr.s_addr;
113 		addr.ipv4_addr.dst_addr =
114 		    ((const struct sockaddr_in *)dstss)->sin_addr.s_addr;
115 		addr.ipv4_addr.src_port = srcport;
116 		addr.ipv4_addr.dst_port = dstport;
117 		break;
118 	case AF_INET6:
119 		hdr.fam = (conf->flags & F_UDP) ?
120 			PROXY_V2_FAM_UDP6 : PROXY_V2_FAM_TCP6;
121 		len = sizeof(addr.ipv6_addr);
122 		bcopy(&((const struct sockaddr_in6 *)srcss)->sin6_addr,
123 		    addr.ipv6_addr.src_addr, sizeof(addr.ipv6_addr.src_addr));
124 		bcopy(&((const struct sockaddr_in6 *)dstss)->sin6_addr,
125 		    addr.ipv6_addr.dst_addr, sizeof(addr.ipv6_addr.dst_addr));
126 		addr.ipv6_addr.src_port = srcport;
127 		addr.ipv6_addr.dst_port = dstport;
128 		break;
129 	default:
130 		hdr.fam = 0x00;
131 		len = 0;
132 		break;
133 	}
134 
135 	hdr.len = htons(len);
136 
137 	if ((error = evbuffer_add(dstout, &hdr, sizeof(hdr))) != 0)
138 		return error;
139 
140 	if (len > 0 && (error = evbuffer_add(dstout, &addr, len)) != 0)
141 		return error;
142 
143 	return 0;
144 }