redis源码笔记－anet
anet库是redis对tcp网络层以及unix域实现的一个封装。redis的客户端和server端通信使用的均为TCP协议。Basic TCP socket stuff made a bit less boring
anet.h
1 #ifndef ANET_H 2 #define ANET_H 3 4 #define ANET_OK 0 5 #define ANET_ERR -1 6 #define ANET_ERR_LEN 256 7 8 #if defined(__sun) 9 #define AF_LOCAL AF_UNIX 10 #endif 11 12 int anetTcpConnect(char *err, char *addr, int port); //错误信息是通过指针参数传入的 13 int anetTcpNonBlockConnect(char *err, char *addr, int port); 14 int anetUnixConnect(char *err, char *path); 15 int anetUnixNonBlockConnect(char *err, char *path); 16 int anetRead(int fd, char *buf, int count); 17 int anetResolve(char *err, char *host, char *ipbuf); 18 int anetTcpServer(char *err, int port, char *bindaddr); 19 int anetUnixServer(char *err, char *path, mode_t perm); 20 int anetTcpAccept(char *err, int serversock, char *ip, int *port); 21 int anetUnixAccept(char *err, int serversock); 22 int anetWrite(int fd, char *buf, int count); 23 int anetNonBlock(char *err, int fd); 24 int anetTcpNoDelay(char *err, int fd); 25 int anetTcpKeepAlive(char *err, int fd); 26 int anetPeerToString(int fd, char *ip, int *port); 27 28 #endif
anet.c
1 #include "fmacros.h" 2 3 #include <sys/types.h> 4 #include <sys/socket.h> 5 #include <sys/stat.h> 6 #include <sys/un.h> 7 #include <netinet/in.h> 8 #include <netinet/tcp.h> 9 #include <arpa/inet.h> 10 #include <unistd.h> 11 #include <fcntl.h> 12 #include <string.h> 13 #include <netdb.h> 14 #include <errno.h> 15 #include <stdarg.h> 16 #include <stdio.h> 17 18 #include "anet.h" 19 20 static void anetSetError(char *err, const char *fmt, ...) 21 { 22 va_list ap; 23 24 if (!err) return; 25 va_start(ap, fmt); 26 vsnprintf(err, ANET_ERR_LEN, fmt, ap); 27 va_end(ap); 28 } 29 30 int anetNonBlock(char *err, int fd) //将一个描述符设成非阻塞 31 { 32 int flags; 33 34 /* Set the socket nonblocking. 35 * Note that fcntl(2) for F_GETFL and F_SETFL can't be 36 * interrupted by a signal. */ 37 if ((flags = fcntl(fd, F_GETFL)) == -1) { 38 anetSetError(err, "fcntl(F_GETFL): %s", strerror(errno)); 39 return ANET_ERR; 40 } 41 if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) { 42 anetSetError(err, "fcntl(F_SETFL,O_NONBLOCK): %s", strerror(errno)); 43 return ANET_ERR; 44 } 45 return ANET_OK; 46 } 47
//将一个tcp描述符设成NoDelay，客户端可能会设置这个选项，禁止NODELAY算法
//如下摘抄自《UNPv1》7.9.2关于TCP_NODELAY套接字选项的讨论
"开启本选项将会禁止TCP的Nagle算法。默认情况下本算法是开启的。
Nagle算法的目的在于减少广域网上小分组的数目。
" 48 int anetTcpNoDelay(char *err, int fd) 49 { 50 int yes = 1; 51 if (setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof(yes)) == -1) 52 { 53 anetSetError(err, "setsockopt TCP_NODELAY: %s", strerror(errno)); 54 return ANET_ERR; 55 } 56 return ANET_OK; 57 } 58 59 int anetSetSendBuffer(char *err, int fd, int buffsize) //设置发送缓冲区大小 60 { 61 if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &buffsize, sizeof(buffsize)) == -1) 62 { 63 anetSetError(err, "setsockopt SO_SNDBUF: %s", strerror(errno)); 64 return ANET_ERR; 65 } 66 return ANET_OK; 67 } 68 69 int anetTcpKeepAlive(char *err, int fd) //设置keep-alive选项 70 { 71 int yes = 1; 72 if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &yes, sizeof(yes)) == -1) { 73 anetSetError(err, "setsockopt SO_KEEPALIVE: %s", strerror(errno)); 74 return ANET_ERR; 75 } 76 return ANET_OK; 77 } 78 79 int anetResolve(char *err, char *host, char *ipbuf) 80 { 81 struct sockaddr_in sa; 82 83 sa.sin_family = AF_INET; 84 if (inet_aton(host, &sa.sin_addr) == 0) { 85 struct hostent *he; 86 87 he = gethostbyname(host); 88 if (he == NULL) { 89 anetSetError(err, "can't resolve: %s", host); 90 return ANET_ERR; 91 } 92 memcpy(&sa.sin_addr, he->h_addr, sizeof(struct in_addr)); 93 } 94 strcpy(ipbuf,inet_ntoa(sa.sin_addr)); 95 return ANET_OK; 96 } 97 98 static int anetCreateSocket(char *err, int domain) { 99 int s, on = 1; 100 if ((s = socket(domain, SOCK_STREAM, 0)) == -1) { 101 anetSetError(err, "creating socket: %s", strerror(errno)); 102 return ANET_ERR; 103 } 104 105 /* Make sure connection-intensive things like the redis benckmark 106 * will be able to close/open sockets a zillion of times */ 107 if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1) { 108 anetSetError(err, "setsockopt SO_REUSEADDR: %s", strerror(errno)); 109 return ANET_ERR; 110 } 111 return s; 112 } 113 114 #define ANET_CONNECT_NONE 0 115 #define ANET_CONNECT_NONBLOCK 1 116 static int anetTcpGenericConnect(char *err, char *addr, int port, int flags) 117 { 118 int s; 119 struct sockaddr_in sa; 120 121 if ((s = anetCreateSocket(err,AF_INET)) == ANET_ERR) 122 return ANET_ERR; 123 124 sa.sin_family = AF_INET; 125 sa.sin_port = htons(port); 126 if (inet_aton(addr, &sa.sin_addr) == 0) { 127 struct hostent *he; 128 129 he = gethostbyname(addr); 130 if (he == NULL) { 131 anetSetError(err, "can't resolve: %s", addr); 132 close(s); 133 return ANET_ERR; 134 } 135 memcpy(&sa.sin_addr, he->h_addr, sizeof(struct in_addr)); 136 } 137 if (flags & ANET_CONNECT_NONBLOCK) { 138 if (anetNonBlock(err,s) != ANET_OK) 139 return ANET_ERR; 140 } 141 if (connect(s, (struct sockaddr*)&sa, sizeof(sa)) == -1) { 142 if (errno == EINPROGRESS && 143 flags & ANET_CONNECT_NONBLOCK) 144 return s; 145 146 anetSetError(err, "connect: %s", strerror(errno)); 147 close(s); 148 return ANET_ERR; 149 } 150 return s; 151 } 152 153 int anetTcpConnect(char *err, char *addr, int port) 154 { 155 return anetTcpGenericConnect(err,addr,port,ANET_CONNECT_NONE); 156 } 157 158 int anetTcpNonBlockConnect(char *err, char *addr, int port) 159 { 160 return anetTcpGenericConnect(err,addr,port,ANET_CONNECT_NONBLOCK); 161 } 162 163 int anetUnixGenericConnect(char *err, char *path, int flags) 164 { 165 int s; 166 struct sockaddr_un sa; 167 168 if ((s = anetCreateSocket(err,AF_LOCAL)) == ANET_ERR) 169 return ANET_ERR; 170 171 sa.sun_family = AF_LOCAL; 172 strncpy(sa.sun_path,path,sizeof(sa.sun_path)-1); 173 if (flags & ANET_CONNECT_NONBLOCK) { 174 if (anetNonBlock(err,s) != ANET_OK) 175 return ANET_ERR; 176 } 177 if (connect(s,(struct sockaddr*)&sa,sizeof(sa)) == -1) { 178 if (errno == EINPROGRESS && 179 flags & ANET_CONNECT_NONBLOCK) 180 return s; 181 182 anetSetError(err, "connect: %s", strerror(errno)); 183 close(s); 184 return ANET_ERR; 185 } 186 return s; 187 } 188 189 int anetUnixConnect(char *err, char *path) 190 { 191 return anetUnixGenericConnect(err,path,ANET_CONNECT_NONE); 192 } 193 194 int anetUnixNonBlockConnect(char *err, char *path) 195 { 196 return anetUnixGenericConnect(err,path,ANET_CONNECT_NONBLOCK); 197 } 198 199 /* Like read(2) but make sure 'count' is read before to return 200 * (unless error or EOF condition is encountered) */ 201 int anetRead(int fd, char *buf, int count) 202 { 203 int nread, totlen = 0; 204 while(totlen != count) { 205 nread = read(fd,buf,count-totlen); 206 if (nread == 0) return totlen; 207 if (nread == -1) return -1; 208 totlen += nread; 209 buf += nread; 210 } 211 return totlen; 212 } 213 214 /* Like write(2) but make sure 'count' is read before to return 215 * (unless error is encountered) */ 216 int anetWrite(int fd, char *buf, int count) 217 { 218 int nwritten, totlen = 0; 219 while(totlen != count) { 220 nwritten = write(fd,buf,count-totlen); 221 if (nwritten == 0) return totlen; 222 if (nwritten == -1) return -1; 223 totlen += nwritten; 224 buf += nwritten; 225 } 226 return totlen; 227 } 228 229 static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len) { 230 if (bind(s,sa,len) == -1) { 231 anetSetError(err, "bind: %s", strerror(errno)); 232 close(s); 233 return ANET_ERR; 234 } 235 if (listen(s, 511) == -1) { /* the magic 511 constant is from nginx */ 236 anetSetError(err, "listen: %s", strerror(errno)); 237 close(s); 238 return ANET_ERR; 239 } 240 return ANET_OK; 241 } 242 243 int anetTcpServer(char *err, int port, char *bindaddr) 244 { 245 int s; 246 struct sockaddr_in sa; 247 248 if ((s = anetCreateSocket(err,AF_INET)) == ANET_ERR) 249 return ANET_ERR; 250 251 memset(&sa,0,sizeof(sa)); 252 sa.sin_family = AF_INET; 253 sa.sin_port = htons(port); 254 sa.sin_addr.s_addr = htonl(INADDR_ANY); 255 if (bindaddr && inet_aton(bindaddr, &sa.sin_addr) == 0) { 256 anetSetError(err, "invalid bind address"); 257 close(s); 258 return ANET_ERR; 259 } 260 if (anetListen(err,s,(struct sockaddr*)&sa,sizeof(sa)) == ANET_ERR) 261 return ANET_ERR; 262 return s; 263 } 264 265 int anetUnixServer(char *err, char *path, mode_t perm) 266 { 267 int s; 268 struct sockaddr_un sa; 269 270 if ((s = anetCreateSocket(err,AF_LOCAL)) == ANET_ERR) 271 return ANET_ERR; 272 273 memset(&sa,0,sizeof(sa)); 274 sa.sun_family = AF_LOCAL; 275 strncpy(sa.sun_path,path,sizeof(sa.sun_path)-1); 276 if (anetListen(err,s,(struct sockaddr*)&sa,sizeof(sa)) == ANET_ERR) 277 return ANET_ERR; 278 if (perm) 279 chmod(sa.sun_path, perm); 280 return s; 281 } 282 283 static int anetGenericAccept(char *err, int s, struct sockaddr *sa, socklen_t *len) { 284 int fd; 285 while(1) { 286 fd = accept(s,sa,len); 287 if (fd == -1) { 288 if (errno == EINTR) 289 continue; 290 else { 291 anetSetError(err, "accept: %s", strerror(errno)); 292 return ANET_ERR; 293 } 294 } 295 break; 296 } 297 return fd; 298 } 299 300 int anetTcpAccept(char *err, int s, char *ip, int *port) { 301 int fd; 302 struct sockaddr_in sa; 303 socklen_t salen = sizeof(sa); 304 if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == ANET_ERR) 305 return ANET_ERR; 306 307 if (ip) strcpy(ip,inet_ntoa(sa.sin_addr)); 308 if (port) *port = ntohs(sa.sin_port); 309 return fd; 310 } 311 312 int anetUnixAccept(char *err, int s) { 313 int fd; 314 struct sockaddr_un sa; 315 socklen_t salen = sizeof(sa); 316 if ((fd = anetGenericAccept(err,s,(struct sockaddr*)&sa,&salen)) == ANET_ERR) 317 return ANET_ERR; 318 319 return fd; 320 } 321 322 int anetPeerToString(int fd, char *ip, int *port) { 323 struct sockaddr_in sa; 324 socklen_t salen = sizeof(sa); 325 326 if (getpeername(fd,(struct sockaddr*)&sa,&salen) == -1) return -1; 327 if (ip) strcpy(ip,inet_ntoa(sa.sin_addr)); 328 if (port) *port = ntohs(sa.sin_port); 329 return 0; 330 }
