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Support interactive password prompts in SOCKS 5.

Browse Source 
This is the first of the ProxyNegotiator implementations to use the
new interaction system. The other two both need more work than just
inserting a prompt and using the result.
This commit is contained in:
Simon Tatham 2021-11-19 14:33:47 +00:00
parent 02aa5610dd
commit 6354dba631
1 changed files with 90 additions and 26 deletions
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116
proxy/socks5.c
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@ -44,6 +44,9 @@ typedef struct Socks5ProxyNegotiator {
unsigned n_chap_attrs;
unsigned chap_attr, chap_attr_len;
unsigned char chap_buf[256];
strbuf *username, *password;
prompts_t *prompts;
int username_prompt_index, password_prompt_index;
int response_addr_length;
ProxyNegotiator pn;
} Socks5ProxyNegotiator;
@ -54,6 +57,8 @@ static ProxyNegotiator *proxy_socks5_new(const ProxyNegotiatorVT *vt)
memset(s, 0, sizeof(*s));
s->pn.vt = vt;
s->auth_methods_offered = strbuf_new();
s->username = strbuf_new();
s->password = strbuf_new_nm();
return &s->pn;
}
@ -61,6 +66,10 @@ static void proxy_socks5_free(ProxyNegotiator *pn)
{
Socks5ProxyNegotiator *s = container_of(pn, Socks5ProxyNegotiator, pn);
strbuf_free(s->auth_methods_offered);
strbuf_free(s->username);
strbuf_free(s->password);
if (s->prompts)
free_prompts(s->prompts);
smemclr(s, sizeof(s));
sfree(s);
}
@ -83,17 +92,25 @@ static void proxy_socks5_process_queue(ProxyNegotiator *pn)
strbuf_clear(s->auth_methods_offered);
/*
* We have two basic kinds of authentication to offer: none at
* all, and password-based systems (whether the password is sent
* in cleartext or proved via CHAP).
*
* We always offer 'none' as an option. We offer 'password' if we
* either have a username and password already from the Conf, or
* we have a Seat available to ask for them interactively. If
* neither, we don't offer those options in the first place.
*/
put_byte(s->auth_methods_offered, SOCKS5_AUTH_NONE);
{
const char *username = conf_get_str(pn->ps->conf, CONF_proxy_username);
const char *password = conf_get_str(pn->ps->conf, CONF_proxy_password);
if (username[0] || password[0]) {
if (socks5_chap_available)
put_byte(s->auth_methods_offered, SOCKS5_AUTH_CHAP);
put_dataz(s->username, conf_get_str(pn->ps->conf, CONF_proxy_username));
put_dataz(s->password, conf_get_str(pn->ps->conf, CONF_proxy_password));
if (pn->itr || (s->username->len && s->password->len)) {
if (socks5_chap_available)
put_byte(s->auth_methods_offered, SOCKS5_AUTH_CHAP);
put_byte(s->auth_methods_offered, SOCKS5_AUTH_PASSWORD);
}
put_byte(s->auth_methods_offered, SOCKS5_AUTH_PASSWORD);
}
put_byte(pn->output, s->auth_methods_offered->len);
@ -144,16 +161,71 @@ static void proxy_socks5_process_queue(ProxyNegotiator *pn)
}
/*
* Process each auth method. Note we can't do this using the
* natural idiom of a switch statement, because there are
* crReturns inside some cases.
* The 'none' auth option requires no further negotiation. If that
* was the one we selected, go straight to making the connection.
*/
if (s->auth_method == SOCKS5_AUTH_NONE) {
/* 'none' auth needs no further negotiation, so skip ahead
* to actually making the connection */
if (s->auth_method == SOCKS5_AUTH_NONE)
goto authenticated;
/*
* Otherwise, we're going to need a username and password, so this
* is the moment to stop and ask for one if we don't already have
* them.
*/
if (pn->itr && (!s->username->len || !s->password->len)) {
s->prompts = proxy_new_prompts(pn->ps);
s->prompts->to_server = true;
s->prompts->from_server = false;
s->prompts->name = dupstr("SOCKS proxy authentication");
if (!s->username->len) {
s->username_prompt_index = s->prompts->n_prompts;
add_prompt(s->prompts, dupstr("Proxy username: "), true);
} else {
s->username_prompt_index = -1;
}
if (!s->password->len) {
s->password_prompt_index = s->prompts->n_prompts;
add_prompt(s->prompts, dupstr("Proxy password: "), false);
} else {
s->password_prompt_index = -1;
}
while (true) {
int prompt_result = seat_get_userpass_input(
interactor_announce(pn->itr), s->prompts);
if (prompt_result > 0) {
break;
} else if (prompt_result == 0) {
pn->aborted = true;
crStopV;
}
crReturnV;
}
if (s->username_prompt_index != -1) {
strbuf_clear(s->username);
put_dataz(s->username,
prompt_get_result_ref(
s->prompts->prompts[s->username_prompt_index]));
}
if (s->password_prompt_index != -1) {
strbuf_clear(s->password);
put_dataz(s->password,
prompt_get_result_ref(
s->prompts->prompts[s->password_prompt_index]));
}
free_prompts(s->prompts);
s->prompts = NULL;
}
/*
* Now process the different auth methods that will use that
* username and password. Note we can't do this using the natural
* idiom of a switch statement, because there are crReturns inside
* some cases.
*/
if (s->auth_method == SOCKS5_AUTH_PASSWORD) {
/*
* SOCKS 5 password auth packet:
@ -162,17 +234,13 @@ static void proxy_socks5_process_queue(ProxyNegotiator *pn)
* pstring username
* pstring password
*/
const char *username = conf_get_str(
pn->ps->conf, CONF_proxy_username);
const char *password = conf_get_str(
pn->ps->conf, CONF_proxy_password);
put_byte(pn->output, SOCKS5_AUTH_PASSWORD_VERSION);
if (!put_pstring(pn->output, username)) {
if (!put_pstring(pn->output, s->username->s)) {
pn->error = dupstr("SOCKS 5 authentication cannot support "
"usernames longer than 255 chars");
crStopV;
}
if (!put_pstring(pn->output, password)) {
if (!put_pstring(pn->output, s->password->s)) {
pn->error = dupstr("SOCKS 5 authentication cannot support "
"passwords longer than 255 chars");
crStopV;
@ -232,10 +300,8 @@ static void proxy_socks5_process_queue(ProxyNegotiator *pn)
/* Second attribute: username */
{
const char *username = conf_get_str(
pn->ps->conf, CONF_proxy_username);
put_byte(pn->output, SOCKS5_AUTH_CHAP_ATTR_USERNAME);
if (!put_pstring(pn->output, username)) {
if (!put_pstring(pn->output, s->username->s)) {
pn->error = dupstr(
"SOCKS 5 CHAP authentication cannot support "
"usernames longer than 255 chars");
@ -289,11 +355,9 @@ static void proxy_socks5_process_queue(ProxyNegotiator *pn)
}
} else if (s->chap_attr==SOCKS5_AUTH_CHAP_ATTR_CHALLENGE) {
/* The CHAP challenge string. Send the response */
const char *password = conf_get_str(
pn->ps->conf, CONF_proxy_password);
strbuf *response = chap_response(
make_ptrlen(s->chap_buf, s->chap_attr_len),
ptrlen_from_asciz(password));
ptrlen_from_strbuf(s->password));
put_byte(pn->output, SOCKS5_AUTH_CHAP_VERSION);
put_byte(pn->output, 1); /* number of attributes */