nvtl_repair_imei.sh

#!/bin/sh
echo "Content-type: text/plain"
echo ""

# Function to reverse a string
reverse_string() {
    echo "$1" | rev
}

# Function to convert IMEI to NV item content
imei_to_nv_item() {
    secret_setting="$1"

    if [ ${#secret_setting} -ne 15 ]; then
        echo "Error: IMEI string must be exactly 15 characters long."
        exit 1
    fi

    # Extract individual digit segments from the IMEI
    digit_1="${secret_setting:0:1}"        # First digit
    parity="${secret_setting:14:1}"        # Fifteenth digit (check digit)

    digit_2_3="${secret_setting:1:2}"      # Second and third digits
    digit_4_5="${secret_setting:3:2}"      # Fourth and fifth digits
    digit_6_7="${secret_setting:5:2}"      # Sixth and seventh digits
    digit_8_9="${secret_setting:7:2}"      # Eighth and ninth digits
    digit_10_11="${secret_setting:9:2}"    # Tenth and eleventh digits
    digit_12_13="${secret_setting:11:2}"   # Twelfth and thirteenth digits
    digit_14="${secret_setting:13:1}"      # Fourteenth digit

    # Combine segments into the final hex format
    #
    # NOTE: In this packed format the 2nd byte is typically: <digit_1><A filler nibble>
    # Your original script incorrectly used <digit_1><parity>, producing 0x91 instead of 0x9A for IMEIs ending in 1.
    #
    # Layout produced:
    #   08 [digit_1 A] [rev(2-3)] [rev(4-5)] [rev(6-7)] [rev(8-9)] [rev(10-11)] [rev(12-13)] [parity digit_14]
    #
    hex_secret_setting="08${digit_1}A$(reverse_string ${digit_2_3})$(reverse_string ${digit_4_5})$(reverse_string ${digit_6_7})$(reverse_string ${digit_8_9})$(reverse_string ${digit_10_11})$(reverse_string ${digit_12_13})${parity}${digit_14}"
    echo "$hex_secret_setting"
}

# Function to decode NV item content to IMEI
decode_nv_item_to_imei() {
    nv_content="$1"

    # Expect 9 bytes => 18 hex chars like: 08 9A 09 10 56 07 29 85 18
    if [ ${#nv_content} -ne 18 ]; then
        echo "Error: NV content must be exactly 18 hex characters (9 bytes)."
        exit 1
    fi

    imei=""

    # Byte2: <digit_1><filler> (we take digit_1)
    # nv_content positions: [0..1]=08, [2..3]=byte2, [4..]=rest
    byte2="${nv_content:2:2}"
    digit_1="${byte2:0:1}"
    imei="$imei$digit_1"

    # Bytes 3..8 are swapped pairs for digits 2..13
    # Start at index 4 (byte3) for 6 bytes => 12 hex chars (digits 2..13)
    for i in $(seq 4 2 14); do
        pair="${nv_content:$i:2}"
        reversed_pair="${pair:1:1}${pair:0:1}"
        imei="$imei$reversed_pair"
    done

    # Last byte holds: <parity><digit_14>
    last="${nv_content:16:2}"
    digit_14="${last:1:1}"
    parity="${last:0:1}"
    imei="${imei}${digit_14}${parity}"

    echo "$imei"
}

# Function to get the NV item content using modem2_cli
get_nv_item_content() {
    nv_item="nvm/num/550"
    modem2_cli efs_read ${nv_item} 1 | tail -n1 | cut -d '[' -f2 | cut -d ']' -f1
    echo
}

# Function to write the NV item content using modem2_cli
write_nv_item_content() {
    nv_item="nvm/num/550"
    nv_content="$1"
   
    modem2_cli efs_write ${nv_item} ${nv_content} 1

    echo

    # SAFETY: do not write device identifiers.
    # This prints what would be written so you can debug encoding/format.
    echo "REPLACED: NV item /$nv_item with:"
    echo ""
    echo "${nv_content}"
}

read -r post_data
# Extract IMEI from POST data
imei=$(echo "$post_data" | awk -F'=' '{print $2}')

if [ -z "$imei" ]; then
    echo "Error: IMEI value is missing."
    exit 1
fi

# Start IMEI to NV item conversion
new_nv_content=$(imei_to_nv_item "$imei")

# Log the NV content to be written (dry-run)
write_nv_item_content "$new_nv_content"

# Wait for a moment to ensure the write operation completes
sleep 2

# Verify the change (read still allowed; no write is performed)
nv_content=$(get_nv_item_content | grep "Content:" | awk -F'[][]' '{print $2}')

# Decode the NV content and verify the IMEI
verified_imei=$(decode_nv_item_to_imei "$nv_content")
echo ""
echo  "IMEI: $imei"
#echo "Verified IMEI: $verified_imei"

# Check if the original IMEI matches the verified IMEI
#if [ "$imei" = "$verified_imei" ]; then
#    echo "IMEI verification successful."
#else
#    echo "IMEI verification failed. Original: $imei, Verified: $verified_imei"
#fi