(Tcl) DNS Query MX Records

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Shows how to perform a DNS query to retrieve MX records.

Note: This example requires Chilkat v9.5.0.96 or later.

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load ./chilkat.dll

set dns [new_CkDns]

set json [new_CkJsonObject]

CkJsonObject_put_EmitCompact $json 0

set success [CkDns_Query $dns "MX" "somebody@gmail.com" $json]
if {$success == 0} then {
    puts [CkDns_lastErrorText $dns]
    delete_CkDns $dns
    delete_CkJsonObject $json
    exit
}

puts [CkJsonObject_emit $json]

# Sample response.
# Parsing code below..

# -------------------------------------------------------------------------------
# Note: Chilkat will return the results sorted by "pref" from lowest to highest.
# -------------------------------------------------------------------------------

# {
#   "answer": {
#     "mx": [
#       {
#         "name": "gmail.com",
#         "ttl": 491,
#         "pref": 5,
#         "domain": "gmail-smtp-in.l.google.com"
#       },
#       {
#         "name": "gmail.com",
#         "ttl": 491,
#         "pref": 10,
#         "domain": "alt1.gmail-smtp-in.l.google.com"
#       },
#       {
#         "name": "gmail.com",
#         "ttl": 491,
#         "pref": 20,
#         "domain": "alt2.gmail-smtp-in.l.google.com"
#       },
#       {
#         "name": "gmail.com",
#         "ttl": 491,
#         "pref": 30,
#         "domain": "alt3.gmail-smtp-in.l.google.com"
#       },
#       {
#         "name": "gmail.com",
#         "ttl": 491,
#         "pref": 40,
#         "domain": "alt4.gmail-smtp-in.l.google.com"
#       }
#     ]
#   }
# }

# Use this online tool to generate parsing code from sample JSON: 
# Generate Parsing Code from JSON

set i 0
set count_i [CkJsonObject_SizeOfArray $json "answer.mx"]
while {$i < $count_i} {
    CkJsonObject_put_I $json $i
    set name [CkJsonObject_stringOf $json "answer.mx[i].name"]
    set ttl [CkJsonObject_IntOf $json "answer.mx[i].ttl"]
    set pref [CkJsonObject_IntOf $json "answer.mx[i].pref"]
    set domain [CkJsonObject_stringOf $json "answer.mx[i].domain"]
    set i [expr $i + 1]
}

delete_CkDns $dns
delete_CkJsonObject $json