C (gcc -lws2_32 + winsock2.h), 408 bytes
Z;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S="HTTP/1.1 200 OK%c%cContent-Length: 408%c%c%c%cZ;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S=%c%s%c,13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}",13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}
This uses the Windows Socket 2 API. I have made many questionable choices for the sake of the golf, so there is likely some instability. Listens to an arbitrary number of HTTP requests on port 1025. Compiled with gcc server.c -o server -lws2_32 (e.g.).
Verification
In Firefox:
[![A picture of the Quine in action on Firefox, showing the full code from earlier.][2]][2]
Here is the Ruby test harness I used to verify integrity:
require "net/http"
puts "Waiting for server to start..."
server_process = IO.popen("server.exe") { |server|
3.times { |i|
response = Net::HTTP.get_response(URI("http://localhost:1025")).body
puts "Response ##{i} obtained:"
puts response
puts "Same as server.c?"
puts File.read("server.c") == response
}
puts "Killing server..."
Process.kill("KILL", server.pid)
}
Which, when run:
λ ruby test-server.rb
Waiting for server to start...
Response #0 obtained:
Z;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S="HTTP/1.1 200 OK%c%cContent-Length: 408%c%c%c%cZ;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S=%c%s%c,13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}",13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}
Same as server.c?
true
Response #1 obtained:
Z;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S="HTTP/1.1 200 OK%c%cContent-Length: 408%c%c%c%cZ;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S=%c%s%c,13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}",13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}
Same as server.c?
true
Response #2 obtained:
Z;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S="HTTP/1.1 200 OK%c%cContent-Length: 408%c%c%c%cZ;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(9,M);sprintf(M,S=%c%s%c,13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}",13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,448,0);}
Same as server.c?
true
Killing server...
Explanation
Using fairly standard quining techniques, although my gcc on Windows does not support the POSIX extension for referencing existing *printf arguments (as in this quine, so we must duplicate quite a few constants. At one point, I tried using unprintable characters in multiple places (`Q="\x02\x00''"), but that seemed to not work well with browsers interfacing with the server.
Here is an expanded version, producing the same output as above (so no longer a quine itself), but commented:
// our socket description integer
Z;
// the server code contained here
main() {
char
// our format string to be passed into sprintf
*S,
// shorthand for our struct sockaddr_in, which is passed to bind and accept
// struct sockaddr_in address = { .sin_family = AF_INET /*=2*/, .sin_port = htons(1025) /*=0x0401*/ };
// [NOTE 1]
Q[16] = { 2, 0, 4, 1 },
// M serves two purposes: 1. to be a sprintf buffer and 2. to be allocated memory to allow WSAStartup to run without crashing
*M = malloc(999);
// usually, wVersionRequired is version of windows sockets required (e.g. 2.1 would be 0x0201 = 513), and would be expressed like MAKEWORD(2,3)
// while wVersionRequired can't be 0, from testing, 9 seems to work.
WSAStartup(9, M);
// the main quine section
sprintf(
// the message buffer
M,
// the format string
S = "HTTP/1.1 200 OK%c%cContent-Length: 412%c%c%c%cZ;main(){char*S,Q[16]={2,0,4,1},*M=malloc(999);WSAStartup(514,M);sprintf(M,S=%c%s%c,13,10,13,10,13,10,34,S,34);bind(Z=socket(2,1,0),Q,16);for(listen(Z,3);;)send(accept(Z,Q,0),M,452,0);}",
// \r\n after 200 OK
13, 10,
// \r\n\r\n after headers
13, 10, 13, 10
// " followed by our string followed by ",
34, S, 34,
);
// binds our socket to our target address
bind(
// creates a socket with a particular configuration.
// socket(
// address family specification; AF_INET == 2, and represents IPv4
// the socket type specification; SOCK_STREAM == 1, and represents two-way connections
// the protocol subtype; 0, since we don't need to specify anything further
// )
// returns a socket description integer
Z = socket(2,1,0),
// the string from earlier, reinterpreted as an address struct
Q,
// the size of the address struct; expected to be 16
16
);
// infinite loop
for(
// but first, to save a semicolon, start listening on our socket
// we arbitrarily choose 3 as a backlog queue size
listen(Z, 3);
;
) {
// reply to the request with the message
send(
// accept a request on the address for our socket
accept(Z, Q, 0),
// the message to report
M,
// its length
452,
// flags; none chosen
0
);
}
}
Note 1: We can omit the more precise property specification .sin_addr = { .s_addr = INADDR_ANY } as INADDR_ANY == 0. If we did need it, we do have the golfy option Q={2,1025,{0}}.
