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/**
@file rexmpp_socks.c
@brief SOCKS5 connection establishment.
@author defanor <defanor@uberspace.net>
@date 2020
@copyright MIT license.
*/
#include <memory.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdint.h>
#include <arpa/inet.h>
#include "rexmpp_socks.h"
enum socks_err
rexmpp_socks_proceed (rexmpp_socks_t *s)
{
ssize_t ret;
if (s->io_state == REXMPP_SOCKS_WRITING) {
ssize_t ret = send(s->fd, s->buf + s->buf_sent,
s->buf_len - s->buf_sent, 0);
if (ret > 0) {
s->buf_sent += ret;
if (s->buf_len == s->buf_sent) {
s->buf_len = 0;
s->io_state = REXMPP_SOCKS_READING;
}
} else if (errno == EAGAIN) {
return REXMPP_SOCKS_E_AGAIN;
} else {
return REXMPP_SOCKS_E_TCP;
}
} else if (s->io_state == REXMPP_SOCKS_READING) {
ret = recv(s->fd, s->buf + s->buf_len,
REXMPP_SOCKS_BUF_LEN - s->buf_len, 0);
if (ret > 0) {
s->buf_len += ret;
if (s->buf[0] != 5) {
return REXMPP_SOCKS_E_VERSION;
}
if (s->buf_len >= 2) {
s->socks_error = s->buf[1];
}
if (s->stage == REXMPP_SOCKS_AUTH) {
if (s->buf_len > 2) {
return REXMPP_SOCKS_E_REPLY;
}
if (s->buf_len == 2) {
if (s->socks_error != 0) {
return REXMPP_SOCKS_E_SOCKS;
}
/* It's okay to not authenticate, now we send a command. */
s->buf[0] = 5; /* SOCKS version 5 */
s->buf[1] = 1; /* Connect */
s->buf[2] = 0; /* Reserved */
s->buf[3] = 3; /* Domain name (todo: IP addresses) */
size_t len = strlen(s->host);
s->buf[4] = len;
memcpy(s->buf + 5, s->host, len);
uint16_t port = htons(s->port);
memcpy(s->buf + 5 + len, &port, 2);
s->buf_len = 7 + len;
s->buf_sent = 0;
s->stage = REXMPP_SOCKS_CMD;
s->io_state = REXMPP_SOCKS_WRITING;
return rexmpp_socks_proceed(s);
}
} else if (s->stage == REXMPP_SOCKS_CMD) {
if (s->buf_len >= 5) {
size_t full_len = 6;
if (s->buf[3] == 1) { /* IPv4 */
full_len += 4;
} else if (s->buf[3] == 3) { /* Domain name */
full_len += s->buf[4] + 1;
} else if (s->buf[3] == 4) { /* IPv6 */
full_len += 16;
} else {
return REXMPP_SOCKS_E_REPLY;
}
if (s->buf_len > full_len) {
return REXMPP_SOCKS_E_REPLY;
}
if (s->buf_len == full_len) {
if (s->socks_error != 0) {
return REXMPP_SOCKS_E_SOCKS;
}
/* We're done. */
s->stage = REXMPP_SOCKS_DONE;
return REXMPP_SOCKS_CONNECTED;
}
}
}
} else if (errno == EAGAIN) {
return REXMPP_SOCKS_E_AGAIN;
} else {
return REXMPP_SOCKS_E_TCP;
}
}
return REXMPP_SOCKS_E_AGAIN;
}
enum socks_err
rexmpp_socks_init (rexmpp_socks_t *s,
int fd,
const char *host,
uint16_t port)
{
s->fd = fd;
s->host = host;
s->port = port;
s->socks_error = 0;
if (strlen(host) > 255) {
return REXMPP_SOCKS_E_HOST;
}
/* Request authentication. */
s->stage = REXMPP_SOCKS_AUTH;
s->io_state = REXMPP_SOCKS_WRITING;
s->buf[0] = 5; /* SOCKS version 5 */
s->buf[1] = 1; /* 1 supported method */
s->buf[2] = 0; /* "no authentication required" */
s->buf_len = 3;
s->buf_sent = 0;
return rexmpp_socks_proceed(s);
}
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