UNP函数笔记二: 基本TCP套接字编程

第四章  基本TCP套接字编程:

#include <sys/socket.h>int socket(int family, int type, int protocol);    family:        AF_INET, AF_INET6, AF_LOCAL(AF_UNIX), AF_ROUTE, AF_KEY    type:        SOCK_STREAM, SOCK_DGRAM, SOCK_SEQPACKET, SOCK_RAW    protocol:        IPPROTO_TCP, IPPROTO_UDP, IPPROTO_SCTP, 0(default)    error return -1#include <sys/socket.h>int connect(int sockfd, const struct sockaddr * servaddr, socklen_t addrlen);    success return 0, error return -1#include <sys/socket.h>int bind(int sockfd, const struct sockaddr * myaddr, socklen_t addrlen);    success return 0, error return -1    server:        IPV4:            struct sockaddr_in servaddr;            servaddr.sin_addr.s_addr = htonl(INADDR_ANY);        IPV6:            struct sockaddr_in6 servaddr;            servaddr.sin6_addr = in6addr_any;#include <sys/socket.h>int listen(int sockfd, int backlog);    success return 0, error return -1    convert active-socket to passive-socket#include <sys/socket.h>int accept(int sockfd, struct sockaddr * cliaddr, socklen_t * addrlen);    error return -1    sockfd should be a passive-socket(listened-socket)#include <unistd.h>pid_t fork(void);    error return -1#include <unistd.h>int execl(const char * pathname, const char * arg0, ... /* (char *)0 */);int execv(const char * pathname, char * const argv[]);int execle(const char * pathname, const char * arg0, ...            /* (char *)0, char * const envp[] */);int execve(const char * pathname, char * const argv[], char * const envp[]);int execlp(const char * filename, const char * arg0, ... /* (char *)0 */);int execvp(const char * filename, char * const argv[]);    success no return, error return -1#include <unistd.h>int close(int sockfd);    success return 0, error return -1#include <sys/socket.h>int getsockname(int sockfd, struct sockaddr * localaddr, socklen_t * addrlen);int getpeername(int sockfd, struct sockaddr * peeraddr, socklen_t * addrlen);    success return 0, error return -1

示例:

#include <stdio.h>#include <errno.h>#include <stdlib.h>#include <string.h>#include <sys/socket.h>void Listen(int fd, int backlog){    char * ptr;    /* can override 2nd argument with environment variable */    if ((ptr = getenv("LISTENQ")) != NULL) {        backlog = atoi(ptr);    }    if (listen(fd, backlog) < 0) {        printf("listen error %s\n", strerror(errno));        exit(1);    }}

#include <time.h>#include <stdio.h>#include <errno.h>#include <stdlib.h>#include <string.h>#include <strings.h>#include <arpa/inet.h>#include <sys/socket.h>#define LISTENQ 5#define MAXLINE 1024intmain(int argc, char **argv){    int                listenfd;    int                 connfd;    socklen_t           len;    struct sockaddr_in  servaddr;    struct sockaddr_in  cliaddr;    char                buff[MAXLINE];    time_t              ticks;    if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {        printf("socket error %s\n", strerror(errno));        exit(1);    }    bzero(&servaddr, sizeof(servaddr));    servaddr.sin_family      = AF_INET;    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);    servaddr.sin_port        = htons(13);  /* daytime server */    if (bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1) {        printf("bind error %s\n", strerror(errno));        exit(1);    }    if (listen(listenfd, LISTENQ) == -1) {        printf("listen error\n");        exit(1);    }    for ( ; ; ) {        len = sizeof(cliaddr);        connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &len);        if (connfd == -1) {            printf("accept error %s\n", strerror(errno));            exit(1);        }        if (inet_ntop(AF_INET, &cliaddr.sin_addr, buff, sizeof(buff)) == NULL) {            printf("inet_ntop error %s\n", strerror(errno));            exit(1);        }        printf("connection from %s, port %d\n", buff, ntohs(cliaddr.sin_port));        ticks = time(NULL);        snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));        len = strlen(buff);        if (write(connfd, buff, len) != len) {            printf("write error %s\n", strerror(errno));            exit(1);        }        if (close(connfd) == -1) {            printf("close error %s\n", strerror(errno));            exit(1);        }    }}

#include <stdio.h>#include <errno.h>#include <stdlib.h>#include <string.h>#include <strings.h>#include <arpa/inet.h>#include <sys/socket.h>#define MAXLINE  1024intmain(int argc, char **argv){    int                 sockfd;    int                 n;    char                recvline[MAXLINE + 1];    struct sockaddr_in  servaddr;    if (argc != 2) {        printf("usage: a.out <IPaddress>\n");        exit(1);    }    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {        printf("socket error %s\n", strerror(errno));        exit(1);    }    bzero(&servaddr, sizeof(servaddr));    servaddr.sin_family = AF_INET;    servaddr.sin_port   = htons(13);/* daytime server */    if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0) {        printf("inet_pton error for %s: %s\n", argv[1], strerror(errno));        exit(1);    }    if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1) {        printf("connect error %s\n", strerror(errno));        exit(1);    }    while ((n = read(sockfd, recvline, MAXLINE)) > 0) {        recvline[n] = 0;  /* null terminate */        if (fputs(recvline, stdout) == EOF) {            printf("fputs error %s\n", strerror(errno));            exit(1);        }    }    if (n < 0) {        printf("read error\n %s\n", strerror(errno));        exit(1);    }    exit(0);}

#include <sys/socket.h>int sockfd_to_family(int sockfd){    struct sockaddr_storage ss;    socklen_t  len;    len = sizeof(ss);    if (getsockname(sockfd, (struct sockaddr *)&ss, &len) < 0) {        return(-1);    }    return(ss.ss_family);}