UNP函数笔记一: 套接字编程简介

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第三章套接字编程简介:

struct in_addr {    in_addr_t  s_addr;};struct sockaddr_in {    uint8_t         sin_len;    sa_family_t     sin_family;    in_port_t       sin_port;    struct in_addr  sin_addr;    char            sin_zero[8];};struct sockaddr {    uint8_t      sa_len;    sa_family_t  sa_family;    char         sa_data[14];};struct in6_addr {    uint8_t  s6_addr[16];};#define SIN6_LENstruct sockaddr_in6 {    uint8_t          sin6_len;    sa_family_t      sin6_family;    in_port_t        sin6_port;    uint32_t         sin6_flowinfo;    struct in6_addr  sin6_addr;    uint32_t         sin6_scope_id;};struct sockaddr_storage {    uint8_t      ss_len;    sa_family_t  ss_family;    ...};#include <netinet/in.h>uint16_t htons(uint16_t host16bitvalue);uint32_t htonl(uint32_t host32bitvalue);uint16_t ntohs(uint16_t net16bitvalue);uint32_t ntohl(uint32_t net32bitvalue);#include <strings.h>void bzero(void * dest, size_t nbytes);void bcopy(const void * src, void * dest, size_t nbytes);int bcmp(const void * ptr1, const void * ptr2, size_t nbytes);#include <string.h>void * memset(void * dest, int c, size_t len);void * memcpy(void * dest, const void * src, size_t nbytes);int memcmp(const void * ptr1, const void * ptr2, size_t nbytes);#include <arpa/inet.h>int inet_aton(const char * strptr, struct in_addr * addrptr);    success return 1, error return 0in_addr_t inet_addr(const char * strptr);    success return net-order-ipv4-addr, error return INADDR_NONE(~0)char * inet_ntoa(struct in_addr inaddr);#include <arpa/inet.h>int inet_pton(int family, const char * strptr, void * addrptr);    success return 1, invalid strptr return 0, error return -1const char * inet_ntop(int family, const void * addrptr,                        char * strptr, size_t len);    #define INET_ADDRSTRLEN    16    #define INET6_ADDRSTRLEN   46

示例:

#include <stdio.h>#include <stdlib.h>int main(int argc, char * argv[]){    union {        short  s;        char   c[sizeof(short)];    } un;    un.s = 0x0102;    if (sizeof(short) == 2) {        if (un.c[0] == 1 && un.c[1] == 2) {            printf("big-endian\n");        }        else if (un.c[0] == 2 && un.c[1] == 1) {            printf("little-endian\n");        }        else {            printf("unknown\n");        }    }    else {        printf("sizeof(short) = %d\n", sizeof(short));    }    exit(0);}

#include <errno.h>#include <string.h>#include <netinet/in.h>int inet_pton(int family, const char *strptr, void *addrptr){    if (family == AF_INET) {        struct in_addr  in_val;        if (inet_aton(strptr, &in_val)) {            memcpy(addrptr, &in_val, sizeof(struct in_addr));            return(1);        }        return(0);    }    errno = EAFNOSUPPORT;    return(-1);}

#include <errno.h>#include <stdio.h>#include <string.h>#include <netinet/in.h>const char * inet_ntop(int family, const void * addrptr, char * strptr, size_t len){    const u_char * p = (const u_char *) addrptr;    if (family == AF_INET) {        char  temp[INET_ADDRSTRLEN];        snprintf(temp, sizeof(temp), "%d.%d.%d.%d",                 p[0], p[1], p[2], p[3]);        if (strlen(temp) >= len) {            errno = ENOSPC;            return(NULL);        }        strcpy(strptr, temp);        return(strptr);    }    errno = EAFNOSUPPORT;    return(NULL);}

#include <stdio.h>#include <string.h>#include <arpa/inet.h>char * sock_ntop(const struct sockaddr * sa, socklen_t salen){    char        portstr[8];    static char str[128];  /* Unix domain is largest */    switch (sa->sa_family)    {        case AF_INET:        {            struct sockaddr_in * sin = (struct sockaddr_in *) sa;            if (inet_ntop(AF_INET, &sin->sin_addr, str, sizeof(str)) == NULL) {                return(NULL);            }            if (ntohs(sin->sin_port) != 0) {                snprintf(portstr, sizeof(portstr), ":%d", ntohs(sin->sin_port));            }            strcat(str, portstr);            return(str);        }    }    return (NULL);}

#include <fcntl.h>#include <errno.h>ssize_t readn(int fd, void * vptr, size_t n){    size_t    nleft;    ssize_t   nread;    char    * ptr;    ptr = vptr;    nleft = n;    while (nleft > 0) {        if ((nread = read(fd, ptr, nleft)) < 0) {            if (errno == EINTR) {                nread = 0;            }            else {                return(-1);            }        }        else if (nread == 0) {            break;        }        nleft -= nread;        ptr   += nread;    }    return(n - nleft);}

#include <fcntl.h>#include <errno.h>ssize_twriten(int fd, const void * vptr, size_t n){    size_t       nleft;    ssize_t      nwritten;    const char * ptr;    ptr = vptr;    nleft = n;    while (nleft > 0) {        if ((nwritten = write(fd, ptr, nleft)) <= 0) {            if (nwritten < 0 && errno == EINTR)                nwritten = 0;            else                return(-1);        }        nleft -= nwritten;        ptr   += nwritten;    }    return(n);}

#include <fcntl.h>#include <errno.h>ssize_t readline(int fd, void * vptr, size_t maxlen){    ssize_t   n;    ssize_t   rc;    char      c;    char    * ptr;    ptr = vptr;    for (n = 1; n < maxlen; n++) {    again:        if ((rc = read(fd, &c, 1)) == 1) {            *ptr++ = c;            if (c == '\n') {                break;            }        }        else if (rc == 0) {            *ptr = 0;            return(n - 1);        }        else {            if (errno == EINTR) {                goto again;            }            return(-1);        }    }    *ptr = 0;    return(n);}

#include <fcntl.h>#include <errno.h>#define MAXLINE  1024static int    read_cnt;static char * read_ptr;static char   read_buf[MAXLINE];static ssize_t my_read(int fd, char * ptr){    if (read_cnt <= 0) {    again:        if ((read_cnt = read(fd, read_buf, sizeof(read_buf))) < 0) {            if (errno == EINTR) {                goto again;            }            return(-1);        }        else if (read_cnt == 0) {            return(0);        }        read_ptr = read_buf;    }    read_cnt--;    *ptr = *read_ptr++;    return(1);}ssize_t readline(int fd, void * vptr, size_t maxlen){    ssize_t   n;    ssize_t   rc;    char      c;    char    * ptr;    ptr = vptr;    for (n = 1; n < maxlen; n++) {        if ((rc = my_read(fd, &c)) == 1) {            *ptr++ = c;            if (c == '\n') {                break;            }        }        else if (rc == 0) {            *ptr = 0;            return(n - 1);        }        else {            return(-1);        }    }    *ptr = 0;    return(n);}ssize_t readlinebuf(void ** vptrptr){    if (read_cnt) {        *vptrptr = read_ptr;    }    return(read_cnt);}