From 78a27efb55e1c509604fe9d96f8c421d6b1bda36 Mon Sep 17 00:00:00 2001
From: Serhii Kostiuk <serhii.o.kostiuk@globallogic.com>
Date: Fri, 6 Jan 2023 18:48:25 +0200
Subject: [GP-1842] Update the Cellular code to use SIM IMSI for Verizon
 detection

The certifications lab uses special SIM cards with non-Verizon ICCID numbers
and Verizon IMSI numbers (MCC/MNC prefixes or PLMN IDs). Update the code to
detect Verizon properly for such "special" SIM cards.
---
 src/atcmd.c  | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 src/atcmd.h  |  2 ++
 src/global.h |  7 ++++-
 3 files changed, 101 insertions(+), 5 deletions(-)

diff --git a/src/atcmd.c b/src/atcmd.c
index 0c4860a..d17c03f 100644
--- a/src/atcmd.c
+++ b/src/atcmd.c
@@ -1300,7 +1300,7 @@ int atcmd_plus_gmi_read(int fd)
 	return 0;
 }
 
-/* ICCID needed for LNA3 to determine carrier */
+/* ICCID needed to detect Verizon on multi-carrier radios */
 int atcmd_plus_iccid_read(int fd)
 {
 	char buf[ATCMD_LINE_SIZE];
@@ -1342,7 +1342,7 @@ int atcmd_plus_iccid_read(int fd)
 	log_debug("buf=%s for %d", buf,strlen(buf));
 	token = atcmd_value_tok(&save);
 	if (!token) {
-		log_debug("atcmd_value_tok model");
+		log_debug("atcmd_value_tok iccid");
 		return -1;
 	} else {
 		log_debug("token is %s",token);
@@ -1371,6 +1371,65 @@ int atcmd_plus_iccid_read(int fd)
 	return 0;
 }
 
+/* IMSI needed to detect Verizon when the ICCID is unrecognized */
+int atcmd_plus_imsi_read(int fd)
+{
+	char buf[ATCMD_LINE_SIZE];
+	char *save;
+	char *token;
+	int tmp;
+	char *tmp_buf;
+	char* command = "AT+CIMI";
+
+	atcmd_writeline(fd, command);
+	//Swallow extra "\r\n"
+	tmp = atcmd_readline(fd, buf, sizeof(buf));
+	if (tmp <= 0) {
+		log_debug("expected \\r\\n but it was not received");
+		return -1;
+	}
+
+	//Read imsi string
+	tmp = atcmd_readline(fd, buf, sizeof(buf));
+	if (tmp <= 0) {
+		log_debug("expected IMSI but it was not received");
+		/* Currently only LNA7/LNA7D/L4G1 models will need the IMSI */
+		return -1;
+	}
+
+	save = buf;
+	log_debug("buf=%s for %d", buf,strlen(buf));
+	token = atcmd_value_tok(&save);
+	if (!token) {
+		log_debug("atcmd_value_tok imsi");
+		return -1;
+	} else {
+		log_debug("token is %s",token);
+	}
+	tmp_buf = strrchr(token,' ');
+	if (tmp_buf) {
+		token = ++tmp_buf;
+		log_debug("Found blank, incrementing tmp");
+	} else {
+		tmp_buf = strrchr(token,'\t');
+		log_debug("Found tab, incrementing tmp");
+		if(tmp_buf)
+			token = ++tmp_buf;
+	}
+	log_debug("token[0]=%2.2x token[1]=%2.2x",token[0],token[1]);
+	strncpy(Global.core.imsi, token, IMSI_LEN);
+
+	log_debug("imsi: %s", Global.core.imsi);
+
+	tmp = atcmd_expect_line(fd, buf, sizeof(buf), "OK");
+	if (tmp <= 0) {
+		log_debug("expected OK but it was not received");
+		return -1;
+	}
+
+	return 0;
+}
+
 int atcmd_init(int fd, int read_timeout)
 {
 	int tmp;
@@ -1437,6 +1496,12 @@ static int sms_atcmd_init(int fd)
 		return -1;
 	}
 
+	tmp = atcmd_plus_imsi_read(fd);
+	if (tmp < 0) {
+		log_error("failed to read SIM IMSI");
+		return -1;
+	}
+
 	tmp = atcmd_plus_cmgf_write(fd, SMS_PDU_MODE);
 	if (tmp < 0) {
 		return -1;
@@ -1566,11 +1631,35 @@ int is_quectel_dual_format(void)
 	    !strncmp(Global.core.model, "EG25", MODEL_LEN))
 	{
 		log_debug("Found Quectel radio with dual SMS format support");
-		/* Verizon Wireless SIM */
+
+		/* Verizon Wireless SIM ICCID */
 		if (strncmp(Global.core.iccid,"891480",6) == 0) {
-			log_debug("Found VZW SIM");
+			log_debug("Found VZW SIM by ICCID");
 			return 1;
 		}
+
+		/* Extract PLMN ID - the first 5 or 6 digits of IMSI.
+		   Assume 6 digits for Verizon.
+		   NOTE: Other carriers may use shorter codes */
+		char plmn_id_str[PLMN_ID_SIZE_VZW] = {0};
+		strncpy(plmn_id_str, Global.core.imsi, PLMN_ID_LEN_VZW);
+
+		/* Parse as integer for easier comparison */
+		int plmn_id_num = atoi(plmn_id_str);
+
+		/* Verizon Wireless SIM MCC/MNC */
+		switch (plmn_id_num) {
+		case 310590:
+		case 310890:
+		case 311270:
+		case 311480:
+		case 312770:
+			log_debug("Found VZW SIM by IMSI");
+			return 1;
+		default:
+			/* ignore, not Verizon */
+			break;
+		};
 	}
 	return 0;
 }
diff --git a/src/atcmd.h b/src/atcmd.h
index 1f15e62..bbab2d7 100644
--- a/src/atcmd.h
+++ b/src/atcmd.h
@@ -117,6 +117,8 @@ int atcmd_plus_cpbr_test(int fd, struct phonebook_store *store);
 
 int atcmd_plus_gmm_read(int fd);
 int atcmd_plus_gmi_read(int fd);
+int atcmd_plus_iccid_read(int fd);
+int atcmd_plus_imsi_read(int fd);
 
 int atcmd_init(int fd, int read_timeout);
 int sms_device_close(int fd);
diff --git a/src/global.h b/src/global.h
index a6073dd..4b83cb5 100644
--- a/src/global.h
+++ b/src/global.h
@@ -14,6 +14,10 @@
 
 #define ICCID_LEN           23
 #define ICCID_SIZE         (ICCID_LEN + 1)
+#define IMSI_LEN            15
+#define IMSI_SIZE          (IMSI_LEN + 1)
+#define PLMN_ID_LEN_VZW     6
+#define PLMN_ID_SIZE_VZW   (PLMN_ID_LEN_VZW + 1)
 #define MODEL_LEN           1023
 #define MODEL_SIZE         (MODEL_LEN + 1)
 #define MANUFACTURER_LEN    1023
@@ -37,7 +41,8 @@ struct global_core {
 	char *msg_store_new;
 	char *pb_store;
 	char model[MODEL_SIZE];
-	char iccid[ICCID_SIZE];  /* Needed for LNA3/Verizon */
+	char iccid[ICCID_SIZE];  /* Needed for Verizon 3GPP2 SMS format detection */
+	char imsi[IMSI_SIZE];  /* Needed for Verizon 3GPP2 SMS format detection */
 	char manufacturer[MANUFACTURER_SIZE];  /* Needed to pick proper manufacturer-specific commands */
 
 	char *editor;
-- 
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