How do you analyse the block after the fact? I mean what tools do you use etc.
It's more of a process, rather than a tool.
E.g. for #477115
My node informed be that it rejected the block with a message like this:
AcceptBlock: Unknown input TxID: 9639dd073e67efc879abb1075fafa4fa23d5fa427c129b2b1dd4f5a5520b408d
Looking into the code of the node, I see that this basically means that the block was trying to spend an input from an "non-existing" transaction (its ID is printed)
So I save the block on a disk in a separate file and then use a code like this:
package main
import (
"fmt"
"io/ioutil"
"github.com/piotrnar/gocoin/lib/btc"
)
func main() {
d, _ := ioutil.ReadFile("477115-0000000000000000013ee4a86822d37a061732e04ee5f41fb77168f193363d1b.bin")
println(d)
bl, _ := btc.NewBlock(d)
println(bl)
bl.BuildTxList()
println(len(bl.Txs))
for i, tx := range bl.Txs {
fmt.Println(i, tx.Hash.String())
for ii, inp := range tx.TxIn {
fmt.Println(" ", ii, inp.Input.String())
}
}
}
... it will print all the TxID inside the block, as well as the inputs they are spending:
https://pastebin.com/LtMKi8pCBrowsing the results for the problematic TxID (9639dd073e67efc879abb1075fafa4fa23d5fa427c129b2b1dd4f5a5520b408d), I see it in two places:
22 7a122ef22468e4af16b010d7acf7aa81e5af3636423c613fd98246c179d79800
0 9639dd073e67efc879abb1075fafa4fa23d5fa427c129b2b1dd4f5a5520b408d-001
[...]
90 9639dd073e67efc879abb1075fafa4fa23d5fa427c129b2b1dd4f5a5520b408d
0 796c96815be92f9351cbdd0cb52df426d4af18504a3734a3a4a8f5352555c4f2-000
This means that tx number 22 was trying to spend output from tx number 90.
Meaning: invalid block.
As for the other block (#474294)
Looking for the missing tx (b11a78c6c61af1cb37586f639050d74b95c2b0fd525623b6cb6a4bb4fba46a0e), you don't find it inside the invalid block.
So you go to blockchain.info and look for it:
https://blockchain.info/tx/b11a78c6c61af1cb37586f639050d74b95c2b0fd525623b6cb6a4bb4fba46a0eThere you see that it was confirmed in (alternative) block #474294.
Which gets you to the conclusion that if (any) block #474294 was trying to spend it, while not including it, it obviously is the reason for it to be invalid.
The rest of the network also has freedom to say nope. but hey at least it makes things interesting. 
