Network programming csapp

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  • IP 地址

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    struct in_addr{
    	unsigned int s_addr
    }
    #include <netinet/in.h>
    unsigned long int  htonl(unsigned long int hostlong);
    unsigned short int  htons(unsigned short int hostshort);
    本地转网络字节序
    unsigned long int ntohl(unsigned long int hostlong);
    unsigned short int ntohs(unsigned short int hostlong);
    网络转本地字节
    均以无符号数转换
    网络字节摩恩为：大端，即有效地位存放在地址高位
    ＃include<arpa/inet.h>
    int inet_aton((const char*cp, struct in_addr *inp);
    点分十进制串(cp)转网络字节序IP(inp)
    int inet_ntoa (struct in_addr in);
    网络字节序IP 转点分十进制

  • Domain structure

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    #include <netdb.h>
    struct host{
    	char *h_name;        // domain name
        char **h_aliases;    // Null-terminated array of domain names
        int h_addrtype;      // host type (AF_INET)
        int h_length;        // length of addr in bytes
        char **h_addr_list;  // Null-terminated array of in_addr strcuts
    }
    struct  hostent * gethostbyname(const char* name);
    strcut hostent *gethostbtaddr(const char* addr,
    				int len(sizeof(addr)),int type(AF_INET))
    success none -null return, else set h_errno

  • Socket structure

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    #include<netinet/in.h>
    struct sockaddr{
    	unsigned short sin_family; // address falily (AF_INET)
        char      sa_data[14];     // address data
    };
    struct sockaddr_in{
    	unsigned short sin_family;// AF_INET
        unsigned short sin_port;  // port number
        unsigned short sin_addr;  //  IP address
        unsigned char sin_zero[8] // pad
    }

  • Socket function

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    #include <sys/typs.h>
    #include <sys/socket.h>
    int socket(inr domain, SOCK_TREAM, int protoctol);
    成功非负，失败－１
    常规调用　: clinetfd = socket(AF_INET,SOCK_STREAM,0);
    int connect(int sockfd, struct sockaddr * server_addr, int addrlen);
    成功０，失败－１
    connect函数与套接字地址为serv_addr服务器连接，阻塞直到连接成功
    int bind(int sockfd, struct *my_addr, int len);
    success 0,eles -1
    将my_addr服务器套接字地址与套接字描述符sockfd绑定，addrlen = sizeof(sockaddr_in);
    int listen(int sockfd, int backlog);
    成功０，失败－１
    将sockfd从主动套接字转为监听套接字，backlog 设置拒绝连接前的等待队列请求数量
    int accept(int listenfd, struct sockaddr *adr, int * addrlen);
    成功非负，失败－１
    等待到达侦听描述符sockfd的连接请求，将客户端套接字地址写入addr, 并返回已链接符
  • 数据传输
  • send
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    #include <sys/socket.h>
    ssize_t send(int sockfd, const void *buf, size_t nbytes, int flags);
    ssize_t sendto(int sockfd, const void *buf, size_t nbytes, int flags, const struct sockaddr *destaddr, socklen_t destlen);
    ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags);
    Returns: number of bytes sent if OK, −1 on error

sendto 可在无连接端口上指定目标地址

  • receive
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    ssize_t recv(int sockfd, void *buf, size_t nbytes, int flags);
    ssize_t recvfrom(int sockfd, void *restrict buf, size_t len, int flags, struct sockaddr *restrict addr, socklen_t *restrict addrlen);
    ssize_t recvmsg(int sockfd, struct msghdr *msg, int flags);