Libcurl HTTP 关于libcurl的相关函数介绍以及参数详见官方说明 curl HTTP Request 一个http请求包含方法、路径、http版本、请求包头请求方法 GET, HEAD, POST, PUT, DELETE, PATCH, OPTIONSGETcurl_easy_setopt(curl, CURLOPT_URL, "http://example.com?id=1")POSTcurl_easy_setopt(curl, CURLOPT_URL, "http://example.com"); curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "username=admin&password=123");PUTcurl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);DELETEcurl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "DELETE"); curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/file.txt");libcurl HTTP 请求包头 默认不设置的包头GET /file1.txt HTTP/1.1 Host: localhost Accept: */*POST /file1.txt HTTP/1.1 Host: localhost Accept: */* Content-Length: 6 Content-Type: application/x-www-form-urlencoded设置自定义包头添加一个包头 Name:Mikestruct curl_slist *list = NULL; list = curl_slist_append(list, "Name: Mike"); curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list); curl_easy_perform(curl); curl_slist_free_all(list); /* free the list again */修改一个包头 Host: Alternativestruct curl_slist *list = NULL; list = curl_slist_append(list, "Host: Alternative"); curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list); curl_easy_perform(curl); curl_slist_free_all(list); /* free the list again */删除一个包头struct curl_slist *list = NULL; list = curl_slist_append(list, "Accept:"); curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list); curl_easy_perform(curl); curl_slist_free_all(list); /* free the list again */提供一个没有内容的包头struct curl_slist *list = NULL; list = curl_slist_append(list, "Moo;"); curl_easy_setopt(curl, CURLOPT_HTTPHEADER, list); curl_easy_perform(curl); curl_slist_free_all(list); /* free the list again */HTTP Response HTTP response code常见HTTP响应码Code Meaning1xx Transient code, a new one follows2xx Things are OK3xx The content is somewhere else4xx Failed because of a client problem5xx Failed because of a server problem获取相应状态码long code;curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &code);除了check curl请求的状态 check服务端返回过来的response statusCodeHTTP Range 如果客户端只希望从远程资源中获得前200个字节，或者在中间某个地方需要300个字节时//只取前两百个字节 curl_easy_setopt(curl, CURLOPT_RANGE, "0-199"); //从索引200开始的文件中的所有内容 curl_easy_setopt(curl, CURLOPT_RANGE, "200-"); //从索引0获取200字节，从索引1000获取200字节 curl_easy_setopt(curl, CURLOPT_RANGE, "0-199,1000-199");HTTP Authentication 用户名密码验证curl_easy_setopt(curl, CURLOPT_USERNAME, "joe"); curl_easy_setopt(curl, CURLOPT_PASSWORD, "secret");验证请求客户端并不能决定发送一个验证请求，当服务有资源需要被保护并且需要请求验证，服务器将会返回一个401和WWW-Authenticate: header，这个header包含了特定的验证方式curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_BASIC); curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_DIGEST); curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_NTLM); curl_easy_setopt(curl, CURLOPT_HTTPAUTH, CURLAUTH_NEGOTIATE);Cookie with libcurl cookie验证当启用cookie engine时 cookie将存储在相关联的句柄内存中读取cookiecurl_easy_setopt(easy, CURLOPT_COOKIEFILE, "cookies.txt");从服务端获取cookie并保存curl_easy_setopt(easy, CURLOPT_COOKIEJAR, "cookies.txt");稍后使用curl_easy_cleanup（）关闭easy句柄时，所有已知的cookie将被写入给定文件。该文件格式是浏览器曾经使用过的众所周知的“ Netscape cookie文件”格式。设置自定义cookie 不激活cookie enginecurl_easy_setopt(easy, CURLOPT_COOKIE, "name=daniel; present=yes;");在其中设置的字符串是将在HTTP请求中发送的原始字符串，并且应采用NAME = VALUE重复序列的格式； 包括分号分隔符cookie内存区存储大量cookieAdd a cookie to the cookie store#define SEP "\\t" /* Tab separates the fields */ char *my_cookie = "example.com" /* Hostname */ SEP "FALSE" /* Include subdomains */ SEP "/" /* Path */ SEP "FALSE" /* Secure */ SEP "0" /* Expiry in epoch time format. 0 == Session */ SEP "foo" /* Name */ SEP "bar"; /* Value */ curl_easy_setopt(curl, CURLOPT_COOKIELIST, my_cookie);Get all cookies from the cookie storestruct curl_slist *cookies curl_easy_getinfo(easy, CURLINFO_COOKIELIST, &cookies); /*这将返回指向cookie的链接列表的指针，并且每个cookie（再次）被指定为cookie文件格式的一行。该列表已分配给您，因此在应用程序处理完该信息后，请不要忘记调用curl_slist_free_all*/Cookie store commands//清除整个内存记录 curl_easy_setopt(curl, CURLOPT_COOKIELIST, "ALL"); //从内存中删除所有会话cookie（无有效期的cookie) curl_easy_setopt(curl, CURLOPT_COOKIELIST, "SESS"); //强制将所有cookie写入先前使用CURLOPT_COOKIEJAR指定的文件名 curl_easy_setopt(curl, CURLOPT_COOKIELIST, "FLUSH"); //从先前用CURLOPT_COOKIEFILE指定的文件名强制重新加载cookie curl_easy_setopt(curl, CURLOPT_COOKIELIST, "RELOAD"); DownloadGET方法请求资源easy = curl_easy_init(); curl_easy_setopt(easy, CURLOPT_URL, "http://example.com/"); curl_easy_perform(easy);如果使用其他方法请求资源向切随后换回get请求curl_easy_setopt(easy, CURLOPT_HTTPGET, 1L);下载相应的返回包头数据 用CURLOPT_HEADEReasy = curl_easy_init(); curl_easy_setopt(easy, CURLOPT_HEADER, 1L); curl_easy_setopt(easy, CURLOPT_URL, "http://example.com/"); curl_easy_perform(easy);或者将包头数据存储到文件easy = curl_easy_init(); FILE *file = fopen("headers", "wb"); curl_easy_setopt(easy, CURLOPT_HEADERDATA, file); curl_easy_setopt(easy, CURLOPT_URL, "http://example.com/"); curl_easy_perform(easy); fclose(file);在开发时设置详细模式，将同时显示发送到stderr的传出和传入标头：curl_easy_setopt(easy, CURLOPT_VERBOSE, 1L);获取一个页面存储到内存#include <stdio.h> #include <stdlib.h> #include <string.h> #include <curl/curl.h> struct MemoryStruct { char *memory; size_t size; }; static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp) { size_t realsize = size * nmemb; struct MemoryStruct *mem = (struct MemoryStruct *)userp; mem->memory = (char*)realloc(mem->memory, mem->size + realsize + 1); if(mem->memory == NULL) { return 0; } memcpy(&(mem->memory[mem->size]), contents, realsize); mem->size += realsize; mem->memory[mem->size] = 0; return realsize; } int main(void) { CURL *curl_handle; CURLcode res; struct MemoryStruct chunk; chunk.memory = malloc(1); chunk.size = 0; curl_global_init(CURL_GLOBAL_ALL); //整个程序全局只需要初始化一次 多次初始化会出问题 curl_handle = curl_easy_init(); curl_easy_setopt(curl_handle, CURLOPT_URL, "https://www.example.com/"); curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback); curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk); //curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0"); res = curl_easy_perform(curl_handle); if(res != CURLE_OK) { fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); } else { printf("%lu bytes retrieved\n", (long)chunk.size); } curl_easy_cleanup(curl_handle); free(chunk.memory); curl_global_cleanup(); return 0; }获取一个文件流的回调函数//下载文件 static size_t Writeback(void* pBuffer, size_t nSize, size_t nMemByte, void* pParam) { //把下载到的数据以追加的方式写入文件(一定要有a，否则前面写入的内容就会被覆盖了) FILE* fp = NULL; fopen_s(&fp, "E:\\test_1.wav", "ab+"); size_t nWrite = fwrite(pBuffer, nSize, nMemByte, fp); fclose(fp); return nWrite; } //如果未设置此回调，则默认情况下libcurl使用'fwriteUploadloadhttp postHTTP请求将数据传递到服务器的标准方法，使用libcurl，通常可以提供该数据作为指针和长度curl_easy_setopt(easy, CURLOPT_POSTFIELDS, dataptr); curl_easy_setopt(easy, CURLOPT_POSTFIELDSIZE, (long)datalength);使用自定义回调函数将不断调用回调函数，直到所有数据都传输或者传输失败 如果未设置此回调，则默认情况下libcurl使用'fread'#include <stdio.h> #include <fcntl.h> #include <sys/stat.h> #include <curl/curl.h> //回调函数的签名 必须按照这个签名实现自己的回调函数 static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *stream) { size_t retcode; curl_off_t nread; retcode = fread(ptr, size, nmemb, stream); nread = (curl_off_t)retcode; fprintf(stderr, "*** We read %" CURL_FORMAT_CURL_OFF_T " bytes from file\n", nread); return retcode; } int main(int argc, char **argv) { CURL *curl; CURLcode res; FILE * hd_src; struct stat file_info; char *file; char *url; if(argc < 3) return 1; file = argv[1]; url = argv[2]; stat(file, &file_info); hd_src = fopen(file, "rb"); curl_global_init(CURL_GLOBAL_ALL); curl = curl_easy_init(); if(curl) { /* we want to use our own read function */ curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback); /* enable uploading */ curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L); /* HTTP PUT please */ curl_easy_setopt(curl, CURLOPT_PUT, 1L); /* specify target URL, and note that this URL should include a file name, not only a directory */ curl_easy_setopt(curl, CURLOPT_URL, url); /* now specify which file to upload */ curl_easy_setopt(curl, CURLOPT_READDATA, hd_src); /* provide the size of the upload, we specicially typecast the value to curl_off_t since we must be sure to use the correct data size */ curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE, (curl_off_t)file_info.st_size); /* Now run off and do what you've been told! */ res = curl_easy_perform(curl); /* Check for errors */ if(res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); /* always cleanup */ curl_easy_cleanup(curl); } fclose(hd_src); /* close the local file */ curl_global_cleanup(); return 0; }HTTP PUT CURLOPT_INFILESIZE_LARGE设置上传的大小curl_easy_setopt(easy, CURLOPT_UPLOAD, 1L); curl_easy_setopt(easy, CURLOPT_INFILESIZE_LARGE, (curl_off_t) size); curl_easy_setopt(easy, CURLOPT_READFUNCTION, read_callback); curl_easy_setopt(easy, CURLOPT_URL, "https://example.com/handle/put"); /*如果不知道在传输之前不知道传输的大小，对于HTTP 1.0，您必须事先提供大小，HTTP 1.1 你可以添加 标头 Transfer-Encoding: chunked 对于HTTP 2及更高版本，则既不需要大小也不需要额外的标头*/