network – Web server using system calls in GB

I'm discovering Go and I want to implement a web server with the help of system calls to better understand how everything works.

I am looking for comments on idiomatic treatment, especially error handling and the use of pointers

I do not particularly worry about the completeness of the code. The main goal was to learn systematic calls to go.

main package

// Simple single-threaded server using system calls instead of the network library.
//
// Features omitted in the go net package:
//
// - TLS
// - Most verification errors
// - Only support bodies that close, no persistent or fragmented connections
// - Redirections
// - Deadlines and cancellation
// - Non-blocking sockets

import (
"Bufio"
"mistakes"
"flag"
"Io"
"log"
"net"
"net / textproto"
"bone"
"StrConv"
"Strings"
"system call"
)

// netSocket is a file descriptor for a system socket.
type netSocket struct {
// system file descriptor.
fd int
}

func (ns netSocket) Read (p []byte) (int, error) {
if len (p) == 0 {
returns 0, nothing
}
n, err: = syscall.Read (ns.fd, p)
if err! = nil {
n = 0
}
return n, err
}

func (ns netSocket) Write (p []byte) (int, error) {
n, err: = syscall.Write (ns.fd, p)
if err! = nil {
n = 0
}
return n, err
}

// Create a new netSocket for the next pending connection request.
func (ns * netSocket) Accept () (* netSocket, error) {
// the doc syscall.ForkLock indicates that the lock is not needed to block acceptance.
nfd, _, err: = syscall.Accept (ns.fd)
if err == nil {
syscall.CloseOnExec (nfd)
}
if err! = nil {
returns zero, err
}
return & netSocket {nfd}, nil
}

func (ns * netSocket) Close () error {
returns syscall.Close (ns.fd)
}

// Create a new socket file descriptor, bind it and listen.
func newNetSocket (ip net.IP, int port) (* netSocket, error) {
// ForkLock docs indicates that socket syscall requires the lock.
syscall.ForkLock.Lock ()
// AF_INET = Address family for IPv4
// SOCK_STREAM = virtual circuit service
// 0: the protocol for SOCK_STREAM, there is only one.
fd, err: = syscall.Socket (syscall.AF_INET, syscall.SOCK_STREAM, 0)
if err! = nil {
return nil, os.NewSyscallError ("socket", err)
}
syscall.ForkLock.Unlock ()

// Allow reuse of recently used addresses.
if err = syscall.SetsockoptInt (fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1); err! = nil {
syscall.Close (fd)
return nil, os.NewSyscallError ("setsockopt", err)
}

// Bind the socket to a port
its: = & syscall.SockaddrInet4 {Port: port}
copy (sa.Addr[:], ip)
if err = syscall.Bind (fd, sa); err! = nil {
return nil, os.NewSyscallError ("bind", err)
}

// Listen for incoming connections.
if err = syscall.Listen (fd, syscall.SOMAXCONN); err! = nil {
return nil, os.NewSyscallError ("listen", err)
}

return & netSocket {fd: fd}, nil
}

struct request
string of the // GET, POST, etc. method
textproto.MIMEHeader header
body   []byte
uri string // The raw URI of the request
proto string // "HTTP / 1.1"
}

func parseRequest (c * netSocket) (* query, error) {
b: = bufio.NewReader (* c)
tp: = textproto.NewReader (b)
req: = new (request)

// First line: parse "GET /index.html HTTP / 1.0"
var s string
s, _ = tp.ReadLine ()
sp: = strings.Split (s, "")
req.method, req.uri, req.proto = sp[0]sp[1]sp[2]

    // analysis headers
mimeHeader, _: = tp.ReadMIMEHeader ()
req.header = mimeHeader

// body analysis
if req.method == "GET" || req.method == "HEAD" {
return req, nil
}
if len (req.header["Content-Length"]) == 0 {
return nil, errors.New ("no content length")
}
length, err: = strconv.Atoi (req.header["Content-Length"][0])
if err! = nil {
returns zero, err
}
body: = make ([]byte, length)
if _, err = io.ReadFull (b, body); err! = nil {
returns zero, err
}
req.body = body
return req, nil
}

func main () {
ipFlag: = flag.String ("ip_addr", "127.0.0.1", "The IP address to use")
portFlag: = flag.Int ("port", 8080, "The port to use.")
flag.Parse ()

ip: = net.ParseIP (* ipFlag)
port: = * portFlag
socket, err: = newNetSocket (ip, port)
report socket.Close ()
if err! = nil {
panic (err)
}

log.Print ("===============")
log.Print ("Server Started!")
log.Print ("===============")
log.Print ()
log.Printf ("addr: http: //% s:% d", ip, port)

for {
// Block until the incoming connection
rw, e: = socket.Accept ()
log.Print ()
log.Print ()
log.Printf ("Incoming Connection")
if e! = nil {
panic
}

// request to read
log.Print ("Request reading")
req, err: = parseRequest (rw)
log.Print ("request:", req)
if err! = nil {
panic (err)
}

// write the answer
log.Print ("Writing the answer")
io.WriteString (rw, "HTTP / 1.1 200 OK  r  n" +
"Content-Type: text / html; charset = utf-8  r  n" +
"Content Length: 20  r  n" +
" r  n" +
"

Hi world

") if err! = nil { log.Print (err.Error ()) Carry on } } }

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[ Politics ] Open question: Who calls a & # 039; national emergency & # 039; then go play golf? .

External Calls – Can not Record Python in ExternalEvaluate

Anaconda 3 was installed on my system and python was registered with the following link:

RegisterExternalEvaluator["Python","C:\Users\atfai\Anaconda3\python.exe"]

I've recently updated libraries in Anaconda 3 and then
ExterneEvaluer and ExternalLanguage the cell has stopped working, giving the following error.

StartExternalSession :: noinstall: No valid installation for the Python system was found with the specified options.

So I erased the cache of ExterneEvaluer using the following command:
ExternalEvaluate`Private`resetCache[]

and tried to register again:

RegisterExternalEvaluator["Python","C:\Users\atfai\Anaconda3\python.exe"]

giving the following weird error:

RegisterExternalEvaluator :: invalid: - Message text not found - (ExternalEvaluate`Private`reason)

I restarted my computer but nothing solves the problem. Please help.

TS CALLS | Money maker talk

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