Add http-dns-round-robin.sh

README.md

@@ -18,6 +18,7 @@ Miscellaneous scripts for different purposes. Mostly unrelated to each other.
 | Infosec<br>Automation | [`make-mac-prefixes.py`](bin/make-mac-prefixes.py)<br>Python 3.6+ | Processes registered MAC address prefixes from [IEEE MA-L Assignments (CSV)](https://standards.ieee.org/products-programs/regauth/) (stdin) to Nmap's [`nmap-mac-prefixes`](https://github.com/nmap/nmap/blob/master/nmap-mac-prefixes)  (stdout) with a few additional unregistered OUIs.<br>`curl https://standards-oui.ieee.org/oui/oui.csv \| make-mac-prefixes.py > nmap-mac-prefixes` |
 | WordPress | [`test-cache-enabler.py`](bin/test-cache-enabler.py)<br>Python 3.6+ | Tests whether the Cache Enabler by KeyCDN (WordPress) is working properly on the URLs given as arguments.<br>`test-cache-enabler.py https://example.com [...]` |
 | Web | [`detect-modified-html-element.sh`](bin/detect-modified-html-element.sh)<br>Shell (bash) | Checks HTML element changes on a web page since last run. Configured via environment variables.<br>Recommended to be executed as a SystemD [service](systemd/detect-modified-html-element.service.example). |
+| Web | [`http-dns-round-robin.sh`](bin/http-dns-round-robin.sh)<br>Shell (bash) | Print HTTP headers for every DNS round-robin IP (IPv4 + IPv6)<br>`http-dns-round-robin.sh URL`|
 | Web | [`product-pricelimiter.sh`](bin/product-pricelimiter.sh)<br>Shell (bash) | Compare product price on a web page with a given maximum price. Use, e.g., developer tools on your browser to find the HTML element containing the price.<br>`product-pricelimiter.sh -u URL -s Selector [-m MaxPrice] [-n N] [-d N]` |
 | Web | <del>`koronarokotusaika.sh`</del><br>Shell (bash) | This script has been removed as koronarokotusaika.fi (bookcovidvaccine.fi) has been shut down on April 28, 2023. |
 | Web | <del>`xxl-product-pricelimiter.sh`</del><br>Shell (bash) | This script has been replaced by the generalized [`product-pricelimiter.sh`](bin/product-pricelimiter.sh) as the HTML structure of XXL.fi has changed. |

bin/http-dns-round-robin.sh

@@ -0,0 +1,51 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Print HTTP headers for every DNS round-robin IP (IPv4 + IPv6)
+#
+# Usage: http-dns-round-robin.sh URL
+#
+# Author : Esa Jokinen (oh2fih)
+# Home   : https://github.com/oh2fih/Misc-Scripts
+# ------------------------------------------------------------------------------
+
+URL="$1"
+
+required_command() {
+  if ! command -v "$1" &> /dev/null; then
+    if [ -z ${2+x} ]; then
+      echo "This script requires ${1}!" >&2
+    else
+      echo "This script requires ${1} ${2}!" >&2
+    fi
+    ((UNMET=UNMET+1))
+  fi
+}
+
+UNMET=0
+
+required_command "curl" "for HTTP connections"
+required_command "dig" "for DNS queries"
+required_command "head"
+required_command "tail"
+required_command "awk"
+
+if [ "$UNMET" -gt 0 ]; then
+  exit 1
+fi
+
+regex='http(s)?://[-A-Za-z0-9\+&@#/%?=~_|!:,.;]*[-A-Za-z0-9\+&@#/%=~_|]'
+if ! [[ $URL =~ $regex ]]; then
+  echo "The first argument was not a valid URL!" >&2
+  exit 1
+fi
+
+HOSTNAME=$(echo "$URL" | awk -F/ '{print $3}')
+
+while read -r ip
+do
+  echo "[${ip}]"
+  curl --resolve "[${HOSTNAME}]:443:${ip}" --silent --head "$URL"
+done <<< "$( \
+  dig +short "$HOSTNAME" A | tail -n 1 \
+  ; dig +short "$HOSTNAME" AAAA | tail -n 1
+)"