anet网络封装

anet是Redis对TCP套接字网络操作的一个封装（Basic TCP socket stuff made a bit less boring）。在学过之前的基本TCP套接字编程后，我们接着来尝试解读Redis是如何封装基本的TCP套接字方法的。

anet接口

/* anet.c -- Basic TCP socket stuff made a bit less boring */
int anetTcpConnect(char *err, char *addr, int port);
int anetTcpNonBlockConnect(char *err, char *addr, int port);
int anetTcpNonBlockBindConnect(char *err, char *addr, int port, char *source_addr);
int anetTcpNonBlockBestEffortBindConnect(char *err, char *addr, int port, char *source_addr);
int anetUnixConnect(char *err, char *path);
int anetUnixNonBlockConnect(char *err, char *path);
int anetRead(int fd, char *buf, int count);
int anetResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len);
int anetResolveIP(char *err, char *host, char *ipbuf, size_t ipbuf_len);
int anetTcpServer(char *err, int port, char *bindaddr, int backlog);
int anetTcp6Server(char *err, int port, char *bindaddr, int backlog);
int anetUnixServer(char *err, char *path, mode_t perm, int backlog);
int anetTcpAccept(char *err, int serversock, char *ip, size_t ip_len, int *port);
int anetUnixAccept(char *err, int serversock);
int anetWrite(int fd, char *buf, int count);
int anetNonBlock(char *err, int fd);
int anetBlock(char *err, int fd);
int anetEnableTcpNoDelay(char *err, int fd);
int anetDisableTcpNoDelay(char *err, int fd);
int anetTcpKeepAlive(char *err, int fd);
int anetSendTimeout(char *err, int fd, long long ms);
int anetPeerToString(int fd, char *ip, size_t ip_len, int *port);
int anetKeepAlive(char *err, int fd, int interval);
int anetSockName(int fd, char *ip, size_t ip_len, int *port);
int anetFormatAddr(char *fmt, size_t fmt_len, char *ip, int port);
int anetFormatPeer(int fd, char *fmt, size_t fmt_len);
int anetFormatSock(int fd, char *fmt, size_t fmt_len);

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错误信息格式化

static void anetSetError(char *err, const char *fmt, ...)
{
    va_list ap;

    if (!err) return;
    va_start(ap, fmt);
    vsnprintf(err, ANET_ERR_LEN, fmt, ap);
    va_end(ap);
}

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格式化错误信息，并保存到err指针所指的内存中。

套接字描述符设置阻塞/非阻塞

int anetSetBlock(char *err, int fd, int non_block) {
    int flags;

    /* Set the socket blocking (if non_block is zero) or non-blocking.
     * Note that fcntl(2) for F_GETFL and F_SETFL can't be
     * interrupted by a signal. */
    if ((flags = fcntl(fd, F_GETFL)) == -1) {   /* F_GETFL: 读取文件状态标识 */
        anetSetError(err, "fcntl(F_GETFL): %s", strerror(errno));
        return ANET_ERR;
    }

    if (non_block)
        flags |= O_NONBLOCK; /* O_NONBLOCK: 非阻塞I/O; */
    else
        flags &= ~O_NONBLOCK;

    if (fcntl(fd, F_SETFL, flags) == -1) {  /* F_SETFL: 设置文件状态标识 */
        anetSetError(err, "fcntl(F_SETFL,O_NONBLOCK): %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

int anetNonBlock(char *err, int fd) {
    return anetSetBlock(err,fd,1);
}

int anetBlock(char *err, int fd) {
    return anetSetBlock(err,fd,0);
}

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通过fcntl实现对套接字描述符的阻塞和非阻塞操作。

KeepAlive选项设置

/* Set TCP keep alive option to detect dead peers. The interval option
 * is only used for Linux as we are using Linux-specific APIs to set
 * the probe send time, interval, and count. */
int anetKeepAlive(char *err, int fd, int interval)
{
    int val = 1;

    if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &val, sizeof(val)) == -1)
    {
        anetSetError(err, "setsockopt SO_KEEPALIVE: %s", strerror(errno));
        return ANET_ERR;
    }

#ifdef __linux__
    /* Default settings are more or less garbage, with the keepalive time
     * set to 7200 by default on Linux. Modify settings to make the feature
     * actually useful. */

    /* Send first probe after interval. */
    val = interval;
    if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, &val, sizeof(val)) < 0) /* TCP_KEEPDILE： 设置连接上如果没有数据发送的话，多久后发送keepalive探测分组，单位是秒 */
    { 
        anetSetError(err, "setsockopt TCP_KEEPIDLE: %s\n", strerror(errno));
        return ANET_ERR;
    }

    /* Send next probes after the specified interval. Note that we set the
     * delay as interval / 3, as we send three probes before detecting
     * an error (see the next setsockopt call). */
    val = interval/3;
    if (val == 0) val = 1;
    if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, &val, sizeof(val)) < 0) /* TCP_KEEPINTVL： 前后两次探测之间的时间间隔，单位是秒 */
    {
        anetSetError(err, "setsockopt TCP_KEEPINTVL: %s\n", strerror(errno));
        return ANET_ERR;
    }

    /* Consider the socket in error state after three we send three ACK
     * probes without getting a reply. */
    val = 3;
    if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, &val, sizeof(val)) < 0) /* TCP_KEEPCNT： 关闭一个非活跃连接之前的最大重试次数 */
    {
        anetSetError(err, "setsockopt TCP_KEEPCNT: %s\n", strerror(errno));
        return ANET_ERR;
    }
#else
    ((void) interval); /* Avoid unused var warning for non Linux systems. */
#endif

    return ANET_OK;
}

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SO_KEEPALIVE：为了保持长连接。不论是服务端还是客户端，一方开启KeepAlive功能后，就会自动在规定时间内向对方发送心跳包，而另一方在收到心跳包后就会自动回复，以告诉对方我仍然在线。因为开启KeepAlive功能需要消耗额外的宽带和流量，所以TCP协议层默认并不开启KeepAlive功能，尽管这微不足道，但在按流量计费的环境下增加了费用。另一方面，KeepAlive设置不合理时可能会因为短暂的网络波动而断开健康的TCP连接。

sysctl -a | grep keepalive 可查看系统的设置。

TCP设置是否有延迟

static int anetSetTcpNoDelay(char *err, int fd, int val)
{
    if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &val, sizeof(val)) == -1)
    {
        anetSetError(err, "setsockopt TCP_NODELAY: %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

int anetEnableTcpNoDelay(char *err, int fd)
{
    return anetSetTcpNoDelay(err, fd, 1);
}

int anetDisableTcpNoDelay(char *err, int fd)
{
    return anetSetTcpNoDelay(err, fd, 0);
}

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启动TCP_NODELAY，就意味着禁用了Nagle算法，允许小包的发送。对于延时敏感型，同时数据传输量比较小的应用，开启TCP_NODELAY选项无疑是一个正确的选择。

设置TCP数据发送缓冲区的大小

int anetSetSendBuffer(char *err, int fd, int buffsize)
{
    if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &buffsize, sizeof(buffsize)) == -1)
    {
        anetSetError(err, "setsockopt SO_SNDBUF: %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

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设置TCP KEEPALIVE

int anetTcpKeepAlive(char *err, int fd)
{
    int yes = 1;
    if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &yes, sizeof(yes)) == -1) {
        anetSetError(err, "setsockopt SO_KEEPALIVE: %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

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设置超时时间

/* Set the socket send timeout (SO_SNDTIMEO socket option) to the specified
 * number of milliseconds, or disable it if the 'ms' argument is zero. */
int anetSendTimeout(char *err, int fd, long long ms) {
    struct timeval tv;

    tv.tv_sec = ms/1000;
    tv.tv_usec = (ms%1000)*1000;
    if (setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) == -1) {
        anetSetError(err, "setsockopt SO_SNDTIMEO: %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

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地址解析的泛型方法

/* anetGenericResolve() is called by anetResolve() and anetResolveIP() to
 * do the actual work. It resolves the hostname "host" and set the string
 * representation of the IP address into the buffer pointed by "ipbuf".
 *
 * If flags is set to ANET_IP_ONLY the function only resolves hostnames
 * that are actually already IPv4 or IPv6 addresses. This turns the function
 * into a validating / normalizing function. */
int anetGenericResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len,
                       int flags)
{
    struct addrinfo hints, *info;
    int rv;

    memset(&hints,0,sizeof(hints));
    if (flags & ANET_IP_ONLY) hints.ai_flags = AI_NUMERICHOST;
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;  /* specify socktype to avoid dups */

    if ((rv = getaddrinfo(host, NULL, &hints, &info)) != 0) {
        anetSetError(err, "%s", gai_strerror(rv));
        return ANET_ERR;
    }
    if (info->ai_family == AF_INET) {
        struct sockaddr_in *sa = (struct sockaddr_in *)info->ai_addr;
        inet_ntop(AF_INET, &(sa->sin_addr), ipbuf, ipbuf_len);
    } else {
        struct sockaddr_in6 *sa = (struct sockaddr_in6 *)info->ai_addr;
        inet_ntop(AF_INET6, &(sa->sin6_addr), ipbuf, ipbuf_len);
    }

    freeaddrinfo(info);
    return ANET_OK;
}

int anetResolve(char *err, char *host, char *ipbuf, size_t ipbuf_len) {
    return anetGenericResolve(err,host,ipbuf,ipbuf_len,ANET_NONE);
}

int anetResolveIP(char *err, char *host, char *ipbuf, size_t ipbuf_len) {
    return anetGenericResolve(err,host,ipbuf,ipbuf_len,ANET_IP_ONLY);
}

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可以根据条件解析host主机名或IPv4、IPv6地址。

设置REUSEADDR

static int anetSetReuseAddr(char *err, int fd) {
    int yes = 1;
    /* Make sure connection-intensive things like the redis benchmark
     * will be able to close/open sockets a zillion of times */
    if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) == -1) {
        anetSetError(err, "setsockopt SO_REUSEADDR: %s", strerror(errno));
        return ANET_ERR;
    }
    return ANET_OK;
}

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确保redis benchmark可以打开/关闭套接字很多次。

创建套接字

static int anetCreateSocket(char *err, int domain) {
    int s;
    if ((s = socket(domain, SOCK_STREAM, 0)) == -1) { /* 套接字类型为SOCK_STREAM，支持的协议族包括AF_INET,AF_INET6和AF_LOCAL */
        anetSetError(err, "creating socket: %s", strerror(errno));
        return ANET_ERR;
    }

    /* Make sure connection-intensive things like the redis benchmark
     * will be able to close/open sockets a zillion of times */
    if (anetSetReuseAddr(err,s) == ANET_ERR) {
        close(s);
        return ANET_ERR;
    }
    return s;
}

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默认开启地址重用。SO_REUSEADDR选项告诉OS如果一个端口处于TIME_WAIT状态, 那么我们就不用等待直接进入使用模式, 不需要继续等待这个时间结束。

通用套接字连接

#define ANET_CONNECT_NONE 0
#define ANET_CONNECT_NONBLOCK 1
#define ANET_CONNECT_BE_BINDING 2 /* Best effort binding. */
static int anetTcpGenericConnect(char *err, char *addr, int port,
                                 char *source_addr, int flags)
{
    int s = ANET_ERR, rv;
    char portstr[6];  /* strlen("65535") + 1; */
    struct addrinfo hints, *servinfo, *bservinfo, *p, *b;

    snprintf(portstr,sizeof(portstr),"%d",port);
    memset(&hints,0,sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    if ((rv = getaddrinfo(addr,portstr,&hints,&servinfo)) != 0) {
        anetSetError(err, "%s", gai_strerror(rv));
        return ANET_ERR;
    }
    for (p = servinfo; p != NULL; p = p->ai_next) {
        /* Try to create the socket and to connect it.
         * If we fail in the socket() call, or on connect(), we retry with
         * the next entry in servinfo. */
        if ((s = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == -1)
            continue;
        if (anetSetReuseAddr(err,s) == ANET_ERR) goto error;
        if (flags & ANET_CONNECT_NONBLOCK && anetNonBlock(err,s) != ANET_OK)
            goto error;
        if (source_addr) {
            int bound = 0;
            /* Using getaddrinfo saves us from self-determining IPv4 vs IPv6 */
            if ((rv = getaddrinfo(source_addr, NULL, &hints, &bservinfo)) != 0)
            {
                anetSetError(err, "%s", gai_strerror(rv));
                goto error;
            }
            for (b = bservinfo; b != NULL; b = b->ai_next) {
                if (bind(s,b->ai_addr,b->ai_addrlen) != -1) {
                    bound = 1;
                    break;
                }
            }
            freeaddrinfo(bservinfo);
            if (!bound) {
                anetSetError(err, "bind: %s", strerror(errno));
                goto error;
            }
        }
        if (connect(s,p->ai_addr,p->ai_addrlen) == -1) {
            /* If the socket is non-blocking, it is ok for connect() to
             * return an EINPROGRESS error here. */
            if (errno == EINPROGRESS && flags & ANET_CONNECT_NONBLOCK)
                goto end;
            close(s);
            s = ANET_ERR;
            continue;
        }

        /* If we ended an iteration of the for loop without errors, we
         * have a connected socket. Let's return to the caller. */
        goto end;
    }
    if (p == NULL)
        anetSetError(err, "creating socket: %s", strerror(errno));

error:
    if (s != ANET_ERR) {
        close(s);
        s = ANET_ERR;
    }

end:
    freeaddrinfo(servinfo);

    /* Handle best effort binding: if a binding address was used, but it is
     * not possible to create a socket, try again without a binding address. */
    if (s == ANET_ERR && source_addr && (flags & ANET_CONNECT_BE_BINDING)) {
        return anetTcpGenericConnect(err,addr,port,NULL,flags);
    } else {
        return s;
    }
}

int anetTcpConnect(char *err, char *addr, int port)
{
    return anetTcpGenericConnect(err,addr,port,NULL,ANET_CONNECT_NONE);
}

int anetTcpNonBlockConnect(char *err, char *addr, int port)
{
    return anetTcpGenericConnect(err,addr,port,NULL,ANET_CONNECT_NONBLOCK);
}

int anetTcpNonBlockBindConnect(char *err, char *addr, int port,
                               char *source_addr)
{
    return anetTcpGenericConnect(err,addr,port,source_addr,
            ANET_CONNECT_NONBLOCK);
}

int anetTcpNonBlockBestEffortBindConnect(char *err, char *addr, int port,
                                         char *source_addr)
{
    return anetTcpGenericConnect(err,addr,port,source_addr,
            ANET_CONNECT_NONBLOCK|ANET_CONNECT_BE_BINDING);
}

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Unix Connect原始接口封装

int anetUnixGenericConnect(char *err, char *path, int flags)
{
    int s;
    struct sockaddr_un sa;

    if ((s = anetCreateSocket(err,AF_LOCAL)) == ANET_ERR)
        return ANET_ERR;

    sa.sun_family = AF_LOCAL;
    strncpy(sa.sun_path,path,sizeof(sa.sun_path)-1);
    if (flags & ANET_CONNECT_NONBLOCK) {
        if (anetNonBlock(err,s) != ANET_OK) {
            close(s);
            return ANET_ERR;
        }
    }
    if (connect(s,(struct sockaddr*)&sa,sizeof(sa)) == -1) {
        if (errno == EINPROGRESS &&
            flags & ANET_CONNECT_NONBLOCK)
            return s;

        anetSetError(err, "connect: %s", strerror(errno));
        close(s);
        return ANET_ERR;
    }
    return s;
}

int anetUnixConnect(char *err, char *path)
{
    return anetUnixGenericConnect(err,path,ANET_CONNECT_NONE);
}

int anetUnixNonBlockConnect(char *err, char *path)
{
    return anetUnixGenericConnect(err,path,ANET_CONNECT_NONBLOCK);
}

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read(2)的封装

/* Like read(2) but make sure 'count' is read before to return
 * (unless error or EOF condition is encountered) */
int anetRead(int fd, char *buf, int count)
{
    ssize_t nread, totlen = 0;
    while(totlen != count) {
        nread = read(fd,buf,count-totlen);
        if (nread == 0) return totlen;
        if (nread == -1) return -1;
        totlen += nread;
        buf += nread;
    }
    return totlen;
}

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对read函数封装，除非发生了错误或者EOF，确保count字节数的数据读取并返回。

write(2)的封装

/* Like write(2) but make sure 'count' is written before to return
 * (unless error is encountered) */
int anetWrite(int fd, char *buf, int count)
{
    ssize_t nwritten, totlen = 0;
    while(totlen != count) {
        nwritten = write(fd,buf,count-totlen);
        if (nwritten == 0) return totlen;
        if (nwritten == -1) return -1;
        totlen += nwritten;
        buf += nwritten;
    }
    return totlen;
}

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对write函数封装，除非发生了错误，确保count字节数的数据写入。

bind和listen函数的封装

static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len, int backlog) {
    if (bind(s,sa,len) == -1) {
        anetSetError(err, "bind: %s", strerror(errno));
        close(s);
        return ANET_ERR;
    }

    if (listen(s, backlog) == -1) {
        anetSetError(err, "listen: %s", strerror(errno));
        close(s);
        return ANET_ERR;
    }
    return ANET_OK;
}

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开启IPV6_V6ONLY选项

static int anetV6Only(char *err, int s) {
    int yes = 1;
    if (setsockopt(s,IPPROTO_IPV6,IPV6_V6ONLY,&yes,sizeof(yes)) == -1) {
        anetSetError(err, "setsockopt: %s", strerror(errno));
        close(s);
        return ANET_ERR;
    }
    return ANET_OK;
}

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开启IPV6_V6ONLY选项将限制它只执行IPv6通信。该选项默认关闭。

泛型TCP服务启动函数

static int _anetTcpServer(char *err, int port, char *bindaddr, int af, int backlog)
{
    int s = -1, rv;
    char _port[6];  /* strlen("65535") */
    struct addrinfo hints, *servinfo, *p;

    snprintf(_port,6,"%d",port);
    memset(&hints,0,sizeof(hints));
    hints.ai_family = af;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE;    /* No effect if bindaddr != NULL */

    if ((rv = getaddrinfo(bindaddr,_port,&hints,&servinfo)) != 0) {
        anetSetError(err, "%s", gai_strerror(rv));
        return ANET_ERR;
    }
    for (p = servinfo; p != NULL; p = p->ai_next) {
        if ((s = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == -1)
            continue;

        if (af == AF_INET6 && anetV6Only(err,s) == ANET_ERR) goto error;
        if (anetSetReuseAddr(err,s) == ANET_ERR) goto error;
        if (anetListen(err,s,p->ai_addr,p->ai_addrlen,backlog) == ANET_ERR) s = ANET_ERR;
        goto end;
    }
    if (p == NULL) {
        anetSetError(err, "unable to bind socket, errno: %d", errno);
        goto error;
    }

error:
    if (s != -1) close(s);
    s = ANET_ERR;
end:
    freeaddrinfo(servinfo);
    return s;
}

int anetTcpServer(char *err, int port, char *bindaddr, int backlog)
{
    return _anetTcpServer(err, port, bindaddr, AF_INET, backlog);
}

int anetTcp6Server(char *err, int port, char *bindaddr, int backlog)
{
    return _anetTcpServer(err, port, bindaddr, AF_INET6, backlog);
}

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Unix服务启动函数

int anetUnixServer(char *err, char *path, mode_t perm, int backlog)
{
    int s;
    struct sockaddr_un sa;

    if ((s = anetCreateSocket(err,AF_LOCAL)) == ANET_ERR)
        return ANET_ERR;

    memset(&sa,0,sizeof(sa));
    sa.sun_family = AF_LOCAL;
    strncpy(sa.sun_path,path,sizeof(sa.sun_path)-1);
    if (anetListen(err,s,(struct sockaddr*)&sa,sizeof(sa),backlog) == ANET_ERR)
        return ANET_ERR;
    if (perm)
        chmod(sa.sun_path, perm);
    return s;
}

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泛型accpet函数的封装

static int anetGenericAccept(char *err, int s, struct sockaddr *sa, socklen_t *len) {
    int fd;
    while(1) {
        fd = accept(s,sa,len);
        if (fd == -1) {
            if (errno == EINTR)
                continue;
            else {
                anetSetError(err, "accept: %s", strerror(errno));
                return ANET_ERR;
            }
        }
        break;
    }
    return fd;
}

int anetTcpAccept(char *err, int s, char *ip, size_t ip_len, int *port) {
    int fd;
    struct sockaddr_storage sa;
    socklen_t salen = sizeof(sa);
    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == -1)
        return ANET_ERR;

    if (sa.ss_family == AF_INET) {
        struct sockaddr_in *s = (struct sockaddr_in *)&sa;
        if (ip) inet_ntop(AF_INET,(void*)&(s->sin_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin_port);
    } else {
        struct sockaddr_in6 *s = (struct sockaddr_in6 *)&sa;
        if (ip) inet_ntop(AF_INET6,(void*)&(s->sin6_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin6_port);
    }
    return fd;
}

int anetUnixAccept(char *err, int s) {
    int fd;
    struct sockaddr_un sa;
    socklen_t salen = sizeof(sa);
    if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == -1)
        return ANET_ERR;

    return fd;
}

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获取peer的地址信息

int anetPeerToString(int fd, char *ip, size_t ip_len, int *port) {
    struct sockaddr_storage sa;
    socklen_t salen = sizeof(sa);

    if (getpeername(fd,(struct sockaddr*)&sa,&salen) == -1) goto error;
    if (ip_len == 0) goto error;

    if (sa.ss_family == AF_INET) {
        struct sockaddr_in *s = (struct sockaddr_in *)&sa;
        if (ip) inet_ntop(AF_INET,(void*)&(s->sin_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin_port);
    } else if (sa.ss_family == AF_INET6) {
        struct sockaddr_in6 *s = (struct sockaddr_in6 *)&sa;
        if (ip) inet_ntop(AF_INET6,(void*)&(s->sin6_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin6_port);
    } else if (sa.ss_family == AF_UNIX) {
        if (ip) strncpy(ip,"/unixsocket",ip_len);
        if (port) *port = 0;
    } else {
        goto error;
    }
    return 0;

error:
    if (ip) {
        if (ip_len >= 2) {
            ip[0] = '?';
            ip[1] = '\0';
        } else if (ip_len == 1) {
            ip[0] = '\0';
        }
    }
    if (port) *port = 0;
    return -1;
}

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地址端口信息格式化

/* Format an IP,port pair into something easy to parse. If IP is IPv6
 * (matches for ":"), the ip is surrounded by []. IP and port are just
 * separated by colons. This the standard to display addresses within Redis. */
int anetFormatAddr(char *buf, size_t buf_len, char *ip, int port) {
    return snprintf(buf,buf_len, strchr(ip,':') ?
           "[%s]:%d" : "%s:%d", ip, port);
}

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格式化peerl的地址和端口信息

/* Like anetFormatAddr() but extract ip and port from the socket's peer. */
int anetFormatPeer(int fd, char *buf, size_t buf_len) {
    char ip[INET6_ADDRSTRLEN];
    int port;

    anetPeerToString(fd,ip,sizeof(ip),&port);
    return anetFormatAddr(buf, buf_len, ip, port);
}

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获取socket的地址信息和格式化

int anetSockName(int fd, char *ip, size_t ip_len, int *port) {
    struct sockaddr_storage sa;
    socklen_t salen = sizeof(sa);

    if (getsockname(fd,(struct sockaddr*)&sa,&salen) == -1) {
        if (port) *port = 0;
        ip[0] = '?';
        ip[1] = '\0';
        return -1;
    }
    if (sa.ss_family == AF_INET) {
        struct sockaddr_in *s = (struct sockaddr_in *)&sa;
        if (ip) inet_ntop(AF_INET,(void*)&(s->sin_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin_port);
    } else {
        struct sockaddr_in6 *s = (struct sockaddr_in6 *)&sa;
        if (ip) inet_ntop(AF_INET6,(void*)&(s->sin6_addr),ip,ip_len);
        if (port) *port = ntohs(s->sin6_port);
    }
    return 0;
}

int anetFormatSock(int fd, char *fmt, size_t fmt_len) {
    char ip[INET6_ADDRSTRLEN];
    int port;

    anetSockName(fd,ip,sizeof(ip),&port);
    return anetFormatAddr(fmt, fmt_len, ip, port);
}

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参考

https://github.com/antirez/redis

# anet网络封装

# anet接口

# 错误信息格式化

# 套接字描述符设置阻塞/非阻塞

# KeepAlive选项设置

# TCP设置是否有延迟

# 设置TCP数据发送缓冲区的大小

# 设置TCP KEEPALIVE

# 设置超时时间

# 地址解析的泛型方法

# 设置REUSEADDR

# 创建套接字

# 通用套接字连接

# Unix Connect原始接口封装

# read(2)的封装

# write(2)的封装

# bind和listen函数的封装

# 开启IPV6_V6ONLY选项

# 泛型TCP服务启动函数

# Unix服务启动函数

# 泛型accpet函数的封装

# 获取peer的地址信息

# 地址端口信息格式化

# 格式化peerl的地址和端口信息

# 获取socket的地址信息和格式化

anet网络封装

anet接口

错误信息格式化

套接字描述符设置阻塞/非阻塞

KeepAlive选项设置

TCP设置是否有延迟

设置TCP数据发送缓冲区的大小

设置TCP KEEPALIVE

设置超时时间

地址解析的泛型方法

设置REUSEADDR

创建套接字

通用套接字连接

Unix Connect原始接口封装

read(2)的封装

write(2)的封装

bind和listen函数的封装

开启IPV6_V6ONLY选项

泛型TCP服务启动函数

Unix服务启动函数

泛型accpet函数的封装

获取peer的地址信息

地址端口信息格式化

格式化peerl的地址和端口信息

获取socket的地址信息和格式化