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/*
* SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <netinet/in.h>
#include <stddef.h>
#include <stdint.h>
#include <errno.h>
#include "esp_err.h"
#include "esp_timer.h"
#include "esp_check.h"
#include "esp_transport_socks_proxy.h"
#include "netdb.h"
#include "string.h"
#include "esp_log.h"
#include "include/esp_transport.h"
static const char *TAG = "transport_proxy";
static const uint32_t SOCKS4_FIX_MESSAGE_SIZE = 8;
#define SOCKS4_RESPONSE_SIZE 8
#define SOCKS_ERROR_IF(cond, err_code, format, ...) do {\
ESP_GOTO_ON_FALSE(!(cond), err_code, Error, TAG, format , ##__VA_ARGS__);\
}while(0)
typedef enum {CONNECT = 0x01, BIND = 0x02} command_socks_t;
typedef struct {
union {
char *user_id;
};
} socks_authentication_data_t;
typedef struct transport_socks_t {
socks_version_t version;
char *proxy_address;
uint16_t proxy_port;
socks_authentication_data_t authentication;
esp_transport_handle_t parent;
} transport_socks_t;
typedef struct __attribute((packed)) socks_request {
uint8_t version;
uint8_t command;
uint16_t destination_port;
uint32_t destination_ip;
} socks_request_t;
typedef struct __attribute((packed)) socks_response {
uint8_t version;
uint8_t code;
uint16_t destination_port;
uint32_t destination_ip;
} socks_response_t;
static uint32_t get_IP(const char *const host)
{
struct addrinfo *address_info;
struct addrinfo hints;
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
int res = getaddrinfo(host, NULL, &hints, &address_info);
if (res) {
// IP_ADDR_ANY equivalent returned as error here because it doesn't make
// sense to connect to ANY
return 0;
}
uint32_t ip = ((struct sockaddr_in *)address_info->ai_addr)->sin_addr.s_addr;
freeaddrinfo(address_info);
return ip;
}
static int64_t get_tick(void)
{
return esp_timer_get_time() / (int64_t)1000;
}
static int socks_connect(esp_transport_handle_t transport, const char *const host, int port, int timeout_ms)
{
transport_socks_t *socks_transport = esp_transport_get_context_data(transport);
int64_t initial_tick = get_tick();
int64_t remaining_time = timeout_ms;
int ret = 0;
uint32_t request_message_len = SOCKS4_FIX_MESSAGE_SIZE + 1;
char *request_message = NULL;
int proxy_connected = esp_transport_connect(socks_transport->parent, socks_transport->proxy_address, socks_transport->proxy_port, remaining_time);
SOCKS_ERROR_IF(proxy_connected == -1, esp_transport_get_errno(socks_transport->parent), "Error connecting to proxy");
if (remaining_time > -1) {
remaining_time = (int64_t)timeout_ms - (get_tick() - initial_tick);
SOCKS_ERROR_IF(remaining_time < 0, SOCKS_TIMEOUT, "Connection Timeout");
}
socks_request_t request = {};
request.version = socks_transport->version;
request.command = CONNECT;
request.destination_port = htons(port);
request.destination_ip = get_IP(host);
SOCKS_ERROR_IF(request.destination_ip == 0, SOCKS_RESPONSE_TARGET_NOT_FOUND, "Failed to resolve target address");
if (socks_transport->authentication.user_id) {
request_message_len += strlen(socks_transport->authentication.user_id);
request_message = calloc(request_message_len, sizeof(char));
if (request_message) {
strcpy(request_message + sizeof(socks_request_t) +1, socks_transport->authentication.user_id);
}
} else {
request_message = calloc(request_message_len, sizeof(char));
}
SOCKS_ERROR_IF(request_message == NULL, ESP_ERR_NO_MEM, "Failed to allocate request message");
memcpy(request_message, (char *)&request, sizeof(socks_request_t));
SOCKS_ERROR_IF(esp_transport_write(socks_transport->parent, request_message, request_message_len, remaining_time) < 0, esp_transport_get_errno(socks_transport->parent), "Failed to write the request message");
if (remaining_time > -1) {
remaining_time = (int64_t)timeout_ms - (get_tick() - initial_tick);
SOCKS_ERROR_IF(remaining_time < 0, SOCKS_TIMEOUT, "Connection Timeout");
}
char proxy_response[SOCKS4_RESPONSE_SIZE];
SOCKS_ERROR_IF(esp_transport_read(socks_transport->parent, proxy_response, SOCKS4_RESPONSE_SIZE, remaining_time) < 0, esp_transport_get_errno(socks_transport->parent), "Failed to get a response");
socks_response_t *response = (socks_response_t *)proxy_response;
SOCKS_ERROR_IF(response->code != SOCKS_RESPONSE_SUCCESS, response->code, "Request Rejected with : %02x", response->code);
free(request_message);
return 0;
Error:
free(request_message);
errno = ret;
return -1;
}
static int socks_close(esp_transport_handle_t transport)
{
transport_socks_t *socks_transport = esp_transport_get_context_data(transport);
return esp_transport_close(socks_transport->parent);
}
static int socks_write(esp_transport_handle_t transport, const char *buffer, int len, int timeout_ms)
{
transport_socks_t *socks_transport = esp_transport_get_context_data(transport);
return esp_transport_write(socks_transport->parent, buffer, len, timeout_ms);
}
static int socks_read(esp_transport_handle_t transport, char *buffer, int len, int timeout_ms)
{
transport_socks_t *socks_transport = esp_transport_get_context_data(transport);
return esp_transport_read(socks_transport->parent, buffer, len, timeout_ms);
}
static int socks_poll_read(esp_transport_handle_t transport, int timeout_ms)
{
transport_socks_t *socks_transport = esp_transport_get_context_data(transport);
return esp_transport_poll_read(socks_transport->parent, timeout_ms);
}
static int socks_poll_write(esp_transport_handle_t transport, int timeout_ms)
{
transport_socks_t *socks_transport = esp_transport_get_context_data(transport);
return esp_transport_poll_write(socks_transport->parent, timeout_ms);
}
static esp_err_t socks_destroy(esp_transport_handle_t transport)
{
if (transport == NULL) {
return ESP_OK;
}
transport_socks_t *socks_transport = esp_transport_get_context_data(transport);
if (socks_transport == NULL) {
return ESP_FAIL;
}
free(socks_transport->proxy_address);
free(socks_transport);
return ESP_OK;
}
static esp_err_t check_parameters(esp_transport_handle_t parent_handle, const esp_transport_socks_proxy_config_t *config)
{
if (parent_handle == NULL) {
ESP_LOGE(TAG, "Parent transport is invalid");
return ESP_FAIL;
}
if (config == NULL || config->address == NULL) {
ESP_LOGE(TAG, "Invalid Configuration");
return ESP_FAIL;
}
return ESP_OK;
}
esp_transport_handle_t esp_transport_socks_proxy_init(esp_transport_handle_t parent_handle, const esp_transport_socks_proxy_config_t *config)
{
if (check_parameters(parent_handle, config) == ESP_FAIL) {
return NULL;
};
int ret = 0;
esp_transport_handle_t transport = esp_transport_init();
SOCKS_ERROR_IF(transport == NULL, ESP_ERR_NO_MEM, "Failed to allocate transport");
transport_socks_t *socks_context = calloc(1, sizeof(transport_socks_t));
SOCKS_ERROR_IF(socks_context == NULL, ESP_ERR_NO_MEM, "Failed to allocate transport context");
esp_transport_set_context_data(transport, socks_context);
esp_transport_set_func(transport, socks_connect, socks_read, socks_write, socks_close, socks_poll_read, socks_poll_write, socks_destroy);
socks_context->parent = parent_handle;
socks_context->proxy_address = strdup(config->address);
SOCKS_ERROR_IF(socks_context->proxy_address == NULL, ESP_ERR_NO_MEM, "Failed to copy proxy address");
socks_context->proxy_port = config->port;
socks_context->version = config->version;
return transport;
Error:
esp_transport_destroy(transport);
errno = ret;
return NULL;
}
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