CS3700-project4/smol-http/http-msg.rkt

207 lines
6.9 KiB
Racket

#lang racket/base
(provide http-msg?
http-msg-headers
http-msg-body
write-http-msg
http-req? make-http-req
http-res? make-http-res
http-body?
empty-http-body
write-http-body)
(require racket/match
racket/port
"./util.rkt")
(module+ test
(require rackunit))
;; ---------------------------------------------------------------------------------------
;; HTTP messages
(struct http-msg [start-line headers body] #:transparent)
(struct http-start-line:req [method path] #:transparent)
(struct http-start-line:res [code] #:transparent)
;; any? -> boolean?
(define (http-req? h)
(and (http-msg? h) (http-start-line:req? (http-msg-start-line h))))
(define (http-res? h)
(and (http-msg? h) (http-start-line:res? (http-msg-start-line h))))
(define (make-msg sln hdrs)
(http-set-headers (http-msg sln (hasheq) empty-http-body) hdrs))
;; (make-http-req method path [hdrs]) -> http-req?
;; method : http-request-method?
;; path : path-string?
;; hdrs : (listof (cons/c symbol? any?))
(define (make-http-req method path [hdrs '()])
(make-msg (http-start-line:req method (build-path path)) hdrs))
;; (make-http-res code [hdrs]) -> http-res?
;; code : http-response-code?
;; hdrs : (listof (cons/c symbol? any?))
(define (make-http-res code [hdrs '()])
(make-msg (http-start-line:res code) hdrs))
;; (http-set-headers msg hdrs) -> http-msg?
;; msg : http-msg?
;; hdrs : (listof (cons/c symbol? any?))
(define (http-set-headers msg hdrs)
(struct-copy http-msg msg
[headers (for/fold ([hdrs (http-msg-headers msg)])
([kv (in-list hdrs)])
(if (cdr kv)
(hash-set hdrs (car kv) (->bytes (cdr kv)))
(hash-remove hdrs (car kv))))]))
;; (http-set-body msg how) -> http-msg?
;; msg : http-msg?
;; how : (or/c http-body? (http-body? . -> . http-body?))
(define (http-set-body msg how)
(define remove-old-headers
(for/list ([kv (in-list (http-body-additional-headers (http-msg-body msg)))])
(cons (car kv) #f)))
(define bdy*
(match how
[(? http-body? bdy*) bdy*]
[(? procedure? f) (f (http-msg-body msg))]))
(http-set-headers (struct-copy http-msg msg [body bdy*])
(append remove-old-headers
(http-body-additional-headers bdy*))))
;; (write-http-msg msg [port]) -> void?
;; msg : http-msg?
;; port : output-port?
(define (write-http-msg msg [port (current-output-port)])
(match-define (http-msg sln hdrs body) msg)
(match sln
[(http-start-line:req mthd path)
(fprintf port "~a ~a HTTP/1.1\r\n" mthd path)]
[(http-start-line:res code)
(fprintf port "HTTP/1.1 ~a ~a\r\n" code (http-response-code-name code))])
(for ([k (in-list (sort (hash-keys hdrs) symbol<?))])
(fprintf port "~a: ~a\r\n" k (hash-ref hdrs k)))
(write-bytes #"\r\n" port)
(write-http-body body port))
;; ==========================================
(module+ test
(define ex-req-/ (make-http-req 'GET "/" '([host . "localhost"])))
(define ex-res-ok (http-set-body (make-http-res 200) #"Hello world"))
(check-pred http-req? ex-req-/)
(check-pred http-res? ex-res-ok)
(check-equal? (hash-ref (http-msg-headers ex-req-/) 'host) #"localhost")
(check-equal? (hash-ref (http-msg-headers ex-res-ok) 'content-length) #"11")
(define-syntax-rule (check-http-msg->bytes msg bs ...)
(check-equal? (let ([p (open-output-bytes)])
(write-http-msg msg p)
(get-output-bytes p))
(bytes-append bs ...)))
(check-http-msg->bytes ex-req-/
#"GET / HTTP/1.1\r\n"
#"host: localhost\r\n"
#"\r\n")
(check-http-msg->bytes ex-res-ok
#"HTTP/1.1 200 OK\r\n"
#"content-length: 11\r\n"
#"\r\n"
#"Hello world")
(check-http-msg->bytes (http-set-body ex-res-ok empty-http-body)
#"HTTP/1.1 200 OK\r\n"
#"\r\n"))
;; ---------------------------------------------------------------------------------------
;; Message bodies
(define (http-body? x)
(or (eq? x #f)
(bytes? x)))
(define empty-http-body #f)
(define (http-body-additional-headers bdy)
(match bdy
[#f '()]
[(? bytes? bs) `([content-length . ,(bytes-length bs)])]))
(define (write-http-body bdy [port (current-output-port)])
(when bdy (write-bytes bdy port)))
;; ---------------------------------------------------------------------------------------
;; Parsing
(struct exn:fail:read-http exn:fail [] #:transparent)
(define (raise-read-http-error . fmt)
(raise (exn:fail:read-http (string-append "read-http-msg: " (apply format fmt))
(current-continuation-marks))))
(define (string->start-line s)
(match (regexp-match #px"^(HTTP/1\\.1 (\\d+) .*)|(([A-Z]+) ([^ ]+) HTTP/1\\.1)$" s)
[(list _ _ code #f #f #f)
(http-start-line:res (string->number code))]
[(list _ #f #f _ method path)
(http-start-line:req (string->symbol method) (build-path path))]
[_ #f]))
(define (string->header-kv s)
(match (regexp-match #px"^([^:]+):\\s*(.*)$" s)
[(list _ k v) (cons (string->symbol (string-downcase k))
(->bytes v))]
[_ #f]))
(define (read-crlf-line port)
(match (regexp-match #px"^([^\r]*)\r\n" port)
[(list _ line) (bytes->string/utf-8 line)]
[_ (port->string port)]))
;; (read-http-msg [port]) -> http-msg?
;; port : input-port?
(define (read-http-msg [port (current-input-port)])
(define sln/str
(read-crlf-line port))
(define sln
(or (string->start-line sln/str)
(raise-read-http-error "invalid start line: ~s" sln/str)))
(define hdrs
(for/list ([hln (in-port read-crlf-line port)])
#:break (string=? hln "")
(or (string->header-kv hln)
(raise-read-http-error "read-http-msg: invalid header line: ~s" hln))))
;; TODO: response body; the reader should be determined by the headers
(make-msg sln hdrs))
;; ==========================================
(module+ test
(define-syntax-rule (check-bytes->http-msg bs ... msg-expr)
(let ([p (open-input-bytes (bytes-append bs ...))])
(check-equal? (read-http-msg p) msg-expr)
(check-eq? (read-char p) eof)))
(check-bytes->http-msg #"GET /foo?a=z HTTP/1.1\r\n"
#"host: foobar\r\n"
#"\r\n"
(make-http-req 'GET "/foo?a=z" '([host . "foobar"])))
(check-bytes->http-msg #"HTTP/1.1 200 OK\r\n"
#"Content-Type: text/html\r\n"
#"\r\n"
(make-http-res 200 '([content-type . "text/html"])))
;; "write --> read" works
(let-values ([(in out) (make-pipe)])
(thread (λ () (write-http-msg ex-req-/ out)))
(check-equal? (read-http-msg in) ex-req-/)))