本文共 3243 字，大约阅读时间需要 10 分钟。

/*	参数释义：		addr：传入服务器地址信息，其中内容将用于创建监听套接字		source_addr：相当于客户端地址信息		flags：这我还真没看明白。。。再最后一块儿，注释给出了，如果没猜错，应该是和仅打开监听套接字有关的*/static int anetTcpGenericConnect(char *err, const char *addr, int port,const 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;	//未指定    hints.ai_socktype = SOCK_STREAM;//有序、可靠、面向连接的双向字节流    if ((rv = getaddrinfo(addr,portstr,&hints,&servinfo)) != 0) {
   	//解析addr信息，存入 servinfo    //不懂一定要看上面的工具包，写了一晚上呢        anetSetError(err, "%s", gai_strerror(rv));	//这个不管它，报错函数而已        return ANET_ERR;    }    for (p = servinfo; p != NULL; p = p->ai_next) {
   		//工具包里有说，给你一个addrinfo，它可能是一串        /* 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)	//这里s成为了监听套接字            continue;	//如果没打开，那就继续循环，无碍        if (anetSetReuseAddr(err,s) == ANET_ERR) goto error;	//设置地址重用        if (flags & ANET_CONNECT_NONBLOCK && anetNonBlock(err,s) != ANET_OK)	//设置非阻塞            goto error;        if (source_addr) {
   	//source_addr：传入参数            int bound = 0;            /* Using getaddrinfo saves us from self-determining IPv4 vs IPv6 */            if ((rv = getaddrinfo(source_addr, NULL, &hints, &bservinfo)) != 0)	//内啥，不多说了啊            {
                   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;            }        }	//for循环到这里结束        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)) {
   	    //#define ANET_CONNECT_BE_BINDING 2 /* Best effort binding. */        return anetTcpGenericConnect(err,addr,port,NULL,flags);    } else {
           return s;    }}

如果还有什么疑惑，可以在评论区留言一起讨论哦。

相见即是缘分，最近正在写《redis源码学习》系列，可以在我的主页找到。

转载地址：https://lion-wu.blog.csdn.net/article/details/108527645 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！