Merge pull request qiniu#4 from pipul/master

go book

Author: xushiwei

chapter5/hello.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+    "io"
+    "log"
+    "net/http"
+)
+
+func helloHandler(w http.ResponseWriter, r *http.Request) {
+    io.WriteString(w, "Hello world!")
+}
+
+func main() {
+    http.HandleFunc("/hello", helloHandler)
+    err := http.ListenAndServe(":8080", nil)
+    if err != nil {
+        log.Fatal("ListenAndServer:", err.Error())
+    }
+}

chapter5/icmptest.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"net"
+	"os"
+	"io"
+	"bytes"
+	"fmt"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Println("Usage: ", os.Args[0], "host")
+		os.Exit(1)
+	}
+	service := os.Args[1]
+
+	conn, err := net.Dial("ip4:icmp", service)
+	checkError(err)
+
+	var msg [512]byte
+	msg[0] = 8  // echo
+	msg[1] = 0  // code 0
+	msg[2] = 0  // checksum, fix later
+	msg[3] = 0  // checksum, fix later
+	msg[4] = 0  // identifier[0]
+	msg[5] = 13 //identifier[1]
+	msg[6] = 0  // sequence[0]
+	msg[7] = 37 // sequence[1]
+	len := 8
+
+	check := checkSum(msg[0:len])
+	msg[2] = byte(check >> 8)
+	msg[3] = byte(check & 255)
+
+	_, err = conn.Write(msg[0:len])
+	checkError(err)
+
+	_, err = conn.Read(msg[0:])
+	checkError(err)
+
+	fmt.Println("Got response")
+	if msg[5] == 13 {
+		fmt.Println("Identifier matches")
+	}
+	if msg[7] == 37 {
+		fmt.Println("Sequence matches")
+	}
+
+	os.Exit(0)
+}
+
+func checkSum(msg []byte) uint16 {
+	sum := 0
+
+	// assume even for now
+	for n := 1; n < len(msg)-1; n += 2 {
+		sum += int(msg[n])*256 + int(msg[n+1])
+	}
+	sum = (sum >> 16) + (sum & 0xffff)
+	sum += (sum >> 16)
+	var answer uint16 = uint16(^sum)
+	return answer
+}
+
+func checkError(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())
+		os.Exit(1)
+	}
+}
+
+func readFully(conn net.Conn) ([]byte, error) {
+	defer conn.Close()
+
+	result := bytes.NewBuffer(nil)
+	var buf [512]byte
+	for {
+		n, err := conn.Read(buf[0:])
+		result.Write(buf[0:n])
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+	}
+	return result.Bytes(), nil
+}

chapter5/jsondemo.go

@@ -0,0 +1,26 @@
+package main
+import ( 
+    "encoding/json"
+    "log"
+    "os"
+)
+
+func main() {
+    dec := json.NewDecoder(os.Stdin)
+    enc := json.NewEncoder(os.Stdout)
+    for {
+        var v map[string]interface{}
+        if err := dec.Decode(&v); err != nil {
+            log.Println(err)
+            return
+        }
+        for k := range v {
+            if k != "Title" {
+                v[k] = nil
+            }
+        }
+        if err := enc.Encode(&v); err != nil {
+            log.Println(err)
+        }
+    }
+} 

chapter5/photoweb.go

@@ -0,0 +1,150 @@
+package main
+
+import (
+    "io"
+    "os"
+    "syscall"
+    "log"
+    "path"
+    "net/http"
+    "io/ioutil"
+    "html/template"
+    "runtime/debug"
+)
+
+const (
+    ListDir      = 0x0001
+    UPLOAD_DIR   = "./uploads"
+    TEMPLATE_DIR = "./views"
+)
+
+templates := make(map[string]*template.Template)
+
+func init() {
+    fileInfoArr, err := ioutil.ReadDir(TEMPLATE_DIR)
+    check(err)
+    var templateName, templatePath string
+
+    for _, fileInfo := range fileInfoArr {
+        templateName = fileInfo.Name()
+        if ext := path.Ext(templateName); ext != ".html" {
+            continue
+        }
+        templatePath = TEMPLATE_DIR + "/" + templateName 
+        log.Println("Loading template:", templatePath) 
+        t := template.Must(template.ParseFiles(templatePath))             
+        templates[templateName] = t
+    }
+}
+
+func check(err error) {
+    if err != nil {
+        panic(err)
+    }
+}
+
+func renderHtml(w http.ResponseWriter, tplName string, locals map[string]interface{}) {
+    if tpl, ok := templates[tplName]; ok {
+        err := tpl.Execute(w, locals)
+        check(err)
+    } else {
+        log.Println("Loading template: ", tplName, "not found!");
+    }
+}
+
+func isExists(path string) (bool, error) {
+    _, err := os.Stat(path)
+    if err == nil {
+        return true, nil
+    }
+    if e, ok := err.(*os.PathError); ok && e.Err == syscall.ENOENT {
+        return false, nil
+    }
+    return false, err
+}
+
+func uploadHandler(w http.ResponseWriter, r *http.Request) {
+    if r.Method == "GET" {
+        renderHtml(w, "upload", nil);
+    }
+    if r.Method == "POST" {
+        f, h, err := r.FormFile("image")
+        check(err)
+        filename := h.Filename
+        defer f.Close()
+        t, err := ioutil.TempFile(UPLOAD_DIR, filename)
+        check(err)
+        defer t.Close()
+        _, err = io.Copy(t, f)
+        check(err)
+        http.Redirect(w, r, "/view?id="+filename, http.StatusFound)
+    }
+}
+
+func viewHandler(w http.ResponseWriter, r *http.Request) {
+    imageId := r.FormValue("id")
+    imagePath := UPLOAD_DIR + "/" + imageId
+    exists, _ := isExists(imagePath)
+    if !exists {
+        http.NotFound(w, r)
+        return
+    }
+
+    w.Header().Set("Content-Type", "image")
+    http.ServeFile(w, r, imagePath)
+}
+
+func listHandler(w http.ResponseWriter, r *http.Request) {
+    fileInfoArr, err := ioutil.ReadDir("./uploads")         
+    check(err)
+    locals := make(map[string]interface{})
+    images := []string{}
+    for _, fileInfo := range fileInfoArr {
+        images = append(images, fileInfo.Name())
+    }
+    locals["images"] = images
+    renderHtml(w, "list", locals)
+}
+
+func safeHandler(fn http.HandlerFunc) http.HandlerFunc {
+    return func(w http.ResponseWriter, r *http.Request) {
+        defer func() {
+            if e, ok := recover().(error); ok {
+                http.Error(w, e.Error(), 
+                http.StatusInternalServerError)                      
+                // 或者输出自定义的 50x 错误页面                     
+                // w.WriteHeader(http.StatusInternalServerError)                     
+                // renderHtml(w, "error", e)                      
+                // logging
+                log.Println("WARN: panic in %v. - %v", fn, e)
+                log.Println(string(debug.Stack()))
+            }
+        }()
+        fn(w, r)
+    }
+}
+
+func staticDirHandler(mux *http.ServeMux, prefix string, staticDir string, flags int) {
+    mux.HandleFunc(prefix, func(w http.ResponseWriter, r *http.Request) {
+        file := staticDir + r.URL.Path[len(prefix)-1:]             
+        if (flags & ListDir) == 0 {
+            if exists, _ := isExists(file); !exists {
+                http.NotFound(w, r)                     
+                return
+            }
+        }
+        http.ServeFile(w, r, file)
+    })
+}
+
+func main() {
+    mux := http.NewServeMux()
+    staticDirHandler(mux, "/assets/", "./public", 0)
+    mux.HandleFunc("/", safeHandler(listHandler))         
+    mux.HandleFunc("/view", safeHandler(viewHandler))         
+    mux.HandleFunc("/upload", safeHandler(uploadHandler))          
+    err := http.ListenAndServe(":8080", mux)
+    if err != nil {
+        log.Fatal("ListenAndServe: ", err.Error())
+    }
+} 

chapter5/simplehttp.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"net"
+	"io"
+	"os"
+	"bytes"
+	"fmt"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "Usage: %s host:port", os.Args[0])
+		os.Exit(1)
+	}
+	service := os.Args[1]
+
+	conn, err := net.Dial("tcp", service)
+	checkError(err)
+
+	_, err = conn.Write([]byte("HEAD / HTTP/1.0\r\n\r\n"))
+	checkError(err)
+
+	result, err := readFully(conn)
+	checkError(err)
+
+	fmt.Println(string(result))
+
+	os.Exit(0)
+}
+
+func checkError(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())
+		os.Exit(1)
+	}
+}
+
+func readFully(conn net.Conn) ([]byte, error) {
+	defer conn.Close()
+
+	result := bytes.NewBuffer(nil)
+	var buf [512]byte
+	for {
+		n, err := conn.Read(buf[0:])
+		result.Write(buf[0:n])
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+	}
+	return result.Bytes(), nil
+}

chapter5/simplehttp2.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"net"
+	"os"
+	"fmt"
+	"io/ioutil"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Fprintf(os.Stderr, "Usage: %s host:port ", os.Args[0])
+		os.Exit(1)
+	}
+	service := os.Args[1]
+
+	tcpAddr, err := net.ResolveTCPAddr("tcp4", service)
+	checkError(err)
+
+	conn, err := net.DialTCP("tcp", nil, tcpAddr)
+	checkError(err)
+
+	_, err = conn.Write([]byte("HEAD / HTTP/1.0\r\n\r\n"))
+	checkError(err)
+
+	//result, err := readFully(conn)
+	result, err := ioutil.ReadAll(conn)
+	checkError(err)
+
+	fmt.Println(string(result))
+
+	os.Exit(0)
+}
+
+func checkError(err error) {
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())
+		os.Exit(1)
+	}
+}