driver: add uqmi backend

This commit adds a backend to interface with an eUICC connected to a
compatible modem using the uqmi application.

This allows OpenWrt to manage an eUICC including the download and
installation of SIM profiles.

This was previously not possible with most modems, as the APDU
operations were aborted due to exceeding the timeout imposed
on the AT interface by the modem firmware.

Tested-on: Quectel EC25 / Quectel EP06 / Quectel RG520N

Signed-off-by: David Bauer <david.bauer@uniberg.com>

driver/CMakeLists.txt

@@ -47,6 +47,9 @@ if(LPAC_WITH_APDU_AT)
     target_sources(euicc-drivers PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/apdu/at.c)
 endif()
 
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DLPAC_WITH_APDU_UQMI")
+target_sources(euicc-drivers PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/apdu/uqmi.c)
+
 if(LPAC_WITH_APDU_GBINDER)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DLPAC_WITH_APDU_GBINDER")
     target_sources(euicc-drivers PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/apdu/gbinder_hidl.c)

driver/apdu/uqmi.c

@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: MIT
+/* Copyright (c) 2024 David Bauer <david.bauer@uniberg.com> */
+
+#include "at.h"
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <cjson/cJSON_ex.h>
+#include <euicc/interface.h>
+#include <euicc/hexutil.h>
+
+static FILE *fuart;
+static int client_id = 0;
+static int logic_channel = 0;
+static char *devpath = NULL;
+
+
+static int uqmi_execute_command(const char *command, char *buf, size_t bufsize)
+{
+    char *debug_str = getenv("LPAC_QMI_DEBUG");
+    char final_command[2048] = {};
+    FILE *fp;
+    char *remaining;
+    int debug = debug_str ? atoi(debug_str) : 0;
+
+    if (debug)
+        printf("UQMI_DEBUG_TX: %s\n", command);
+
+    if (snprintf(final_command, sizeof(final_command), "uqmi -s -d %s %s", devpath, command) >= sizeof(final_command))
+    {
+        fprintf(stderr, "Command too long\n");
+        return -1;
+    }
+
+    fp = popen(final_command, "r");
+    if (fp == NULL)
+    {
+        fprintf(stderr, "Failed to execute command: %s\n", command);
+        return -1;
+    }
+
+    remaining = buf;
+    if (buf) {
+        while (fgets(remaining, bufsize - (remaining - buf), fp) != NULL)
+        {
+            /* Read to buffer */
+        }
+        if (debug)
+            printf("UQMI_DEBUG_RX: %s", buf);
+    }
+
+    pclose(fp);
+    return 0;
+}
+
+static int uqmi_open_client()
+{
+    char buffer[2048] = {};
+    int ret;
+
+    ret = uqmi_execute_command("--get-client-id uim", buffer, sizeof(buffer));
+    if (ret)
+    {
+        return -1;
+    }
+
+    client_id = atoi(buffer);
+    if (client_id == 0)
+    {
+        return -1;
+    }
+
+    return 0;
+}
+
+static int apdu_interface_connect(struct euicc_ctx *ctx)
+{
+    const char *device;
+
+    client_id = 0;
+    logic_channel = 0;
+    devpath = getenv("LPAC_QMI_DEV");
+
+    return uqmi_open_client();
+}
+
+static void apdu_interface_disconnect(struct euicc_ctx *ctx)
+{
+    char command[64] = {};
+
+    snprintf(command, sizeof(command), "--set-client-id uim,%d --release-client-id uim", client_id);
+    uqmi_execute_command(command, NULL, 0);
+
+    client_id = 0;
+    logic_channel = 0;
+}
+
+static int apdu_interface_transmit(struct euicc_ctx *ctx, uint8_t **rx, uint32_t *rx_len, const uint8_t *tx, uint32_t tx_len)
+{
+    cJSON *root = NULL, *jtmp = NULL;
+    char cmd[2048] = {};
+    char buf[2048] = {};
+    char *json;
+
+    *rx = NULL;
+    *rx_len = 0;
+
+    if (!client_id)
+    {
+        return -1;
+    }
+
+    if (!logic_channel)
+    {
+        return -1;
+    }
+
+    for (int i = 0; i < tx_len; i++)
+    {
+        snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf), "%02X", (uint8_t)(tx[i] & 0xFF));
+    }
+
+    snprintf(cmd, sizeof(cmd), "--set-client-id uim,%d --keep-client-id uim --uim-slot 1 --uim-channel-id %d --uim-apdu-send \"%s\"",
+             client_id, logic_channel, buf);
+    uqmi_execute_command(cmd, buf, sizeof(buf));
+
+    json = strstr(buf, "{");
+    if (!json)
+    {
+        printf("No JSON found\n");
+        goto fail;
+    }
+
+    root = cJSON_Parse(json);
+    if (!root)
+    {
+        printf("Failed to parse JSON\n");
+        goto fail;
+    }
+
+    jtmp = cJSON_GetObjectItem(root, "response");
+    if (!jtmp || !cJSON_IsString(jtmp))
+    {
+        printf("Failed to get response\n");
+        goto fail;
+    }
+
+    *rx_len = strlen(jtmp->valuestring) / 2;
+    *rx = malloc(*rx_len);
+    if (euicc_hexutil_hex2bin_r(*rx, *rx_len, jtmp->valuestring, strlen(jtmp->valuestring)) < 0)
+    {
+        printf("Failed to convert hex '%s' to binary\n", jtmp->valuestring);
+        goto fail;
+    }
+
+    cJSON_Delete(root);
+    return 0;
+fail:
+    if (root)
+    {
+        cJSON_Delete(root);
+    }
+
+    if (*rx)
+    {
+        free(*rx);
+    }
+    *rx_len = 0;
+    return -1;
+}
+
+static int apdu_interface_logic_channel_open(struct euicc_ctx *ctx, const uint8_t *aid, uint8_t aid_len)
+{
+    char *response, *json;
+    char buf[2048] = {};
+    char cmd[2048] = {};
+    cJSON *root, *jtmp;
+
+    if (!client_id)
+    {
+        return -1;
+    }
+
+    if (logic_channel)
+    {
+        return logic_channel;
+    }
+
+    snprintf(cmd, sizeof(cmd), "--set-client-id uim,%d --keep-client-id uim --uim-slot 1 --uim-channel-open ", client_id);
+    for (int i = 0; i < aid_len; i++)
+    {
+        snprintf(cmd + strlen(cmd), sizeof(cmd) - strlen(cmd), "%02X", (uint8_t)(aid[i] & 0xFF));
+    }
+
+    uqmi_execute_command(cmd, buf, sizeof(buf));
+
+    json = strstr(buf, "{");
+    if (!json)
+    {
+        printf("No JSON found\n");
+        return -1;
+    }
+
+    root = cJSON_Parse(json);
+    if (!root)
+    {
+        printf("Failed to parse JSON\n");
+        return -1;
+    }
+
+    jtmp = cJSON_GetObjectItem(root, "channel_id");
+    if (!jtmp || !cJSON_IsNumber(jtmp))
+    {
+        printf("Failed to get channel_id\n");
+        cJSON_Delete(root);
+        return -1;
+    }
+
+    logic_channel = jtmp->valueint;
+
+    cJSON_Delete(root);
+    return logic_channel;
+}
+
+static void apdu_interface_logic_channel_close(struct euicc_ctx *ctx, uint8_t channel)
+{
+    char cmd[2048] = {};
+
+    if (!logic_channel)
+    {
+        return;
+    }
+
+    snprintf(cmd, sizeof(cmd), "--set-client-id uim,%d --keep-client-id uim --uim-slot 1 --uim-channel-id %d --uim-channel-close", client_id, logic_channel);
+    uqmi_execute_command(cmd, NULL, 0);
+    logic_channel = 0;
+    return;
+}
+
+static int libapduinterface_init(struct euicc_apdu_interface *ifstruct)
+{
+    memset(ifstruct, 0, sizeof(struct euicc_apdu_interface));
+
+    ifstruct->connect = apdu_interface_connect;
+    ifstruct->disconnect = apdu_interface_disconnect;
+    ifstruct->logic_channel_open = apdu_interface_logic_channel_open;
+    ifstruct->logic_channel_close = apdu_interface_logic_channel_close;
+    ifstruct->transmit = apdu_interface_transmit;
+
+    return 0;
+}
+
+static int libapduinterface_main(int argc, char **argv)
+{
+    return 0;
+}
+
+static void libapduinterface_fini(void)
+{
+}
+
+const struct euicc_driver driver_apdu_uqmi = {
+    .type = DRIVER_APDU,
+    .name = "uqmi",
+    .init = (int (*)(void *))libapduinterface_init,
+    .main = libapduinterface_main,
+    .fini = libapduinterface_fini,
+};

driver/apdu/uqmi.h

@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: MIT
+/* Copyright (c) 2024 David Bauer <david.bauer@uniberg.com> */
+
+#pragma once
+#include <driver.private.h>
+
+extern const struct euicc_driver driver_apdu_uqmi;

driver/driver.c

@@ -22,6 +22,9 @@
 #ifdef LPAC_WITH_APDU_AT
 #include "driver/apdu/at.h"
 #endif
+#ifdef LPAC_WITH_APDU_UQMI
+#include "driver/apdu/uqmi.h"
+#endif
 #ifdef LPAC_WITH_HTTP_CURL
 #include "driver/http/curl.h"
 #endif
@@ -44,6 +47,9 @@ static const struct euicc_driver *drivers[] = {
 #ifdef LPAC_WITH_APDU_AT
     &driver_apdu_at,
 #endif
+#ifdef LPAC_WITH_APDU_UQMI
+    &driver_apdu_uqmi,
+#endif
 #ifdef LPAC_WITH_HTTP_CURL
     &driver_http_curl,
 #endif