CODEWITHSUNDEEP
sslhttpswinsockwinsock2
user1692342
user1692342

Reputation: 5237

How to wait for entire buffer to arrive in a SSL connection

I am implementing a client server program, in which the client sends HTTP messages to the server. It can be both HTTP or HTTPS In case of large messages, like file transfer using HTTP, the client sends the whole message at one go, whereas it reaches the server in multiple fragments( the network does it). I wait for the entire message to come, and keep merging it so that I get the whole message. Content length is found using a parameter I send in the HTTP message. But in the case of HTTPS there is no way to know if the enitre message has arrived. If i decrypt the fragment, it returns junk values. I think that is because, the whole encrypted message must be joined before decrypting it. How is it possible to identify if the entire message has arrived in HTTPs I am using SSL library and using windows sockets.

Upvotes: 0

Views: 1047

Answers (1)

Remy Lebeau
Remy Lebeau

Reputation: 596041

SSL encrypts plain data into blocks and then those blocks are transmitted individually to the other party. The receiver needs to read the raw socket data and pump it into the SSL decryption engine as it arrives. When the engine has enough bytes for a given block, it decrypts that block and outputs the plain data for just that block. So you simply keep reading socket data and pumping it into the decryption engine, buffering whatever plain data is outputted, until you encounter a decrypted <CRLF><CRLF> sequence denoting the end of the HTTP message headers, then you process those headers to determine whether the HTTP message body is present and how it is encoded. If a message body is present, keep reading socket data, pumping it into the decryption engine, and buffering the output plain data, until you encounter the end of the message body. RFC 2616 Section 4.4 - "Message Length" describes how to determine the encoding of the HTTP message body (after decryption is applied) and what condition terminates the message body.

In other words, you are not supposed to look for the end of an encrypted socket message. You are supposed to decrypt everything you receive until you detect the end of the decrypted HTTP message.

Upvotes: 2

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