我想创建一个非常简单的C应用程序来执行HTTP发布。它将需要一些参数，并使用它们来构造URL。我只想做一个简单的HTTP POST并在不使用curl的情况下获得响应（这些库不会也不会安装在需要运行的机器上）。
的伪代码：
处理2 args
将args放入模板网址：http://api.somesite.com/apikey=ARG1&command=ARG2
对生成的网址执行POST
消费回应
我的Google和SO搜索在这件事上没有任何结果。
答案 0 :(得分：154)
邮件的标题部分和邮件正文用空行分隔。即使没有消息正文，也总是需要空白行。标题以命令开头，并且具有由冒号和空格分隔的其他键值对。如果有一个消息体，它可以是你想要的任何东西。
标题中的行和标题末尾的空白行必须以carraige返回和换行符对结束（请参阅HTTP header line break style），这就是为什么这些行最后都有\ r \ n。
网址格式为http://host:port/path?query_string
向网站提交请求有两种主要方式：
GET：查询字符串是可选的，但如果指定，则必须相当短。因此，标题可能只是GET命令而没有别的。示例消息可以是：
GET /path?query_string HTTP/1.0\r\n
\r\n
POST：查询字符串中通常包含的内容是在邮件正文中。因此，标头需要包含Content-Type：和Content-Length：属性以及POST命令。示例消息可以是：
POST /path HTTP/1.0\r\n
Content-Type: text/plain\r\n
Content-Length: 12\r\n
\r\n
query_string
所以，回答你的问题：如果你感兴趣的帖子是http://api.somesite.com/apikey=ARG1&command=ARG2，那么没有正文或查询字符串，因此没有理由发帖，因为没有任何内容可以放入正文消息，所以没有什么可以放在Content-Type：和Content-Length：
如果你真的想，我猜你可以发帖。在这种情况下，您的消息将如下所示：
POST /apikey=ARG1&command=ARG2 HTTP/1.0\r\n
\r\n
所以要发送C程序需要的消息：
发送和接收呼叫不一定会发送/接收您提供的所有数据 - 它们将返回实际发送/接收的字节数。您可以在循环中调用它们并发送/接收消息的其余部分。
我在这个示例中没有做的是任何类型的真实错误检查 - 当出现故障我退出程序时。让我知道它是否适合你：
#include <stdio.h> /* printf, sprintf */
#include <stdlib.h> /* exit */
#include <unistd.h> /* read, write, close */
#include <string.h> /* memcpy, memset */
#include <sys/socket.h> /* socket, connect */
#include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
#include <netdb.h> /* struct hostent, gethostbyname */
void error(const char *msg) { perror(msg); exit(0); }
int main(int argc,char *argv[])
{
/* first what are we going to send and where are we going to send it? */
int portno = 80;
char *host = "api.somesite.com";
char *message_fmt = "POST /apikey=%s&command=%s HTTP/1.0\r\n\r\n";
struct hostent *server;
struct sockaddr_in serv_addr;
int sockfd, bytes, sent, received, total;
char message[1024],response[4096];
if (argc < 3) { puts("Parameters: <apikey> <command>"); exit(0); }
/* fill in the parameters */
sprintf(message,message_fmt,argv[1],argv[2]);
printf("Request:\n%s\n",message);
/* create the socket */
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) error("ERROR opening socket");
/* lookup the ip address */
server = gethostbyname(host);
if (server == NULL) error("ERROR, no such host");
/* fill in the structure */
memset(&serv_addr,0,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
/* connect the socket */
if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
/* send the request */
total = strlen(message);
sent = 0;
do {
bytes = write(sockfd,message+sent,total-sent);
if (bytes < 0)
error("ERROR writing message to socket");
if (bytes == 0)
break;
sent+=bytes;
} while (sent < total);
/* receive the response */
memset(response,0,sizeof(response));
total = sizeof(response)-1;
received = 0;
do {
bytes = read(sockfd,response+received,total-received);
if (bytes < 0)
error("ERROR reading response from socket");
if (bytes == 0)
break;
received+=bytes;
} while (received < total);
if (received == total)
error("ERROR storing complete response from socket");
/* close the socket */
close(sockfd);
/* process response */
printf("Response:\n%s\n",response);
return 0;
}
像其他答案所指出的那样，4096字节不是一个非常大的响应。我随机选择了这个数字，假设您的请求响应很短。如果它可能很大，你有两个选择：
回答评论中提出的问题的其他信息：
如果您想在邮件正文中发布数据怎么办？然后，您需要包含Content-Type：和Content-Length：标头。 Content-Length：是将标题与正文分开的空白行之后的所有内容的实际长度。
以下示例采用以下命令行参数：
因此，对于原始问题，您将运行：
a.out api.somesite.com 80 GET "/apikey=ARG1&command=ARG2"
对于评论中提出的问题，你会跑：
a.out api.somesite.com 80 POST / "name=ARG1&value=ARG2" "Content-Type: application/x-www-form-urlencoded"
以下是代码：
#include <stdio.h> /* printf, sprintf */
#include <stdlib.h> /* exit, atoi, malloc, free */
#include <unistd.h> /* read, write, close */
#include <string.h> /* memcpy, memset */
#include <sys/socket.h> /* socket, connect */
#include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
#include <netdb.h> /* struct hostent, gethostbyname */
void error(const char *msg) { perror(msg); exit(0); }
int main(int argc,char *argv[])
{
int i;
/* first where are we going to send it? */
int portno = atoi(argv[2])>0?atoi(argv[2]):80;
char *host = strlen(argv[1])>0?argv[1]:"localhost";
struct hostent *server;
struct sockaddr_in serv_addr;
int sockfd, bytes, sent, received, total, message_size;
char *message, response[4096];
if (argc < 5) { puts("Parameters: <host> <port> <method> <path> [<data> [<headers>]]"); exit(0); }
/* How big is the message? */
message_size=0;
if(!strcmp(argv[3],"GET"))
{
message_size+=strlen("%s %s%s%s HTTP/1.0\r\n"); /* method */
message_size+=strlen(argv[3]); /* path */
message_size+=strlen(argv[4]); /* headers */
if(argc>5)
message_size+=strlen(argv[5]); /* query string */
for(i=6;i<argc;i++) /* headers */
message_size+=strlen(argv[i])+strlen("\r\n");
message_size+=strlen("\r\n"); /* blank line */
}
else
{
message_size+=strlen("%s %s HTTP/1.0\r\n");
message_size+=strlen(argv[3]); /* method */
message_size+=strlen(argv[4]); /* path */
for(i=6;i<argc;i++) /* headers */
message_size+=strlen(argv[i])+strlen("\r\n");
if(argc>5)
message_size+=strlen("Content-Length: %d\r\n")+10; /* content length */
message_size+=strlen("\r\n"); /* blank line */
if(argc>5)
message_size+=strlen(argv[5]); /* body */
}
/* allocate space for the message */
message=malloc(message_size);
/* fill in the parameters */
if(!strcmp(argv[3],"GET"))
{
if(argc>5)
sprintf(message,"%s %s%s%s HTTP/1.0\r\n",
strlen(argv[3])>0?argv[3]:"GET", /* method */
strlen(argv[4])>0?argv[4]:"/", /* path */
strlen(argv[5])>0?"?":"", /* ? */
strlen(argv[5])>0?argv[5]:""); /* query string */
else
sprintf(message,"%s %s HTTP/1.0\r\n",
strlen(argv[3])>0?argv[3]:"GET", /* method */
strlen(argv[4])>0?argv[4]:"/"); /* path */
for(i=6;i<argc;i++) /* headers */
{strcat(message,argv[i]);strcat(message,"\r\n");}
strcat(message,"\r\n"); /* blank line */
}
else
{
sprintf(message,"%s %s HTTP/1.0\r\n",
strlen(argv[3])>0?argv[3]:"POST", /* method */
strlen(argv[4])>0?argv[4]:"/"); /* path */
for(i=6;i<argc;i++) /* headers */
{strcat(message,argv[i]);strcat(message,"\r\n");}
if(argc>5)
sprintf(message+strlen(message),"Content-Length: %d\r\n",strlen(argv[5]));
strcat(message,"\r\n"); /* blank line */
if(argc>5)
strcat(message,argv[5]); /* body */
}
/* What are we going to send? */
printf("Request:\n%s\n",message);
/* create the socket */
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) error("ERROR opening socket");
/* lookup the ip address */
server = gethostbyname(host);
if (server == NULL) error("ERROR, no such host");
/* fill in the structure */
memset(&serv_addr,0,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
/* connect the socket */
if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
/* send the request */
total = strlen(message);
sent = 0;
do {
bytes = write(sockfd,message+sent,total-sent);
if (bytes < 0)
error("ERROR writing message to socket");
if (bytes == 0)
break;
sent+=bytes;
} while (sent < total);
/* receive the response */
memset(response,0,sizeof(response));
total = sizeof(response)-1;
received = 0;
do {
bytes = read(sockfd,response+received,total-received);
if (bytes < 0)
error("ERROR reading response from socket");
if (bytes == 0)
break;
received+=bytes;
} while (received < total);
if (received == total)
error("ERROR storing complete response from socket");
/* close the socket */
close(sockfd);
/* process response */
printf("Response:\n%s\n",response);
free(message);
return 0;
}
答案 1 :(得分：9)
memset(response, 0, sizeof(response));
total = sizeof(response)-1;
received = 0;
do {
printf("RESPONSE: %s\n", response);
// HANDLE RESPONSE CHUCK HERE BY, FOR EXAMPLE, SAVING TO A FILE.
memset(response, 0, sizeof(response));
bytes = recv(sockfd, response, 1024, 0);
if (bytes < 0)
printf("ERROR reading response from socket");
if (bytes == 0)
break;
received+=bytes;
} while (1);
答案 2 :(得分：7)
经过数周的研究。我想出了以下代码。我相信这是使用SSL与Web服务器建立安全连接所需的最低限度。
#include <stdio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/bio.h>
#define APIKEY "YOUR_API_KEY"
#define HOST "YOUR_WEB_SERVER_URI"
#define PORT "443"
int main() {
//
// Initialize the variables
//
BIO* bio;
SSL* ssl;
SSL_CTX* ctx;
//
// Registers the SSL/TLS ciphers and digests.
//
// Basically start the security layer.
//
SSL_library_init();
//
// Creates a new SSL_CTX object as a framework to establish TLS/SSL
// or DTLS enabled connections
//
ctx = SSL_CTX_new(SSLv23_client_method());
//
// -> Error check
//
if (ctx == NULL)
{
printf("Ctx is null\n");
}
//
// Creates a new BIO chain consisting of an SSL BIO
//
bio = BIO_new_ssl_connect(ctx);
//
// Use the variable from the beginning of the file to create a
// string that contains the URL to the site that you want to connect
// to while also specifying the port.
//
BIO_set_conn_hostname(bio, HOST ":" PORT);
//
// Attempts to connect the supplied BIO
//
if(BIO_do_connect(bio) <= 0)
{
printf("Failed connection\n");
return 1;
}
else
{
printf("Connected\n");
}
//
// The bare minimum to make a HTTP request.
//
char* write_buf = "POST / HTTP/1.1\r\n"
"Host: " HOST "\r\n"
"Authorization: Basic " APIKEY "\r\n"
"Connection: close\r\n"
"\r\n";
//
// Attempts to write len bytes from buf to BIO
//
if(BIO_write(bio, write_buf, strlen(write_buf)) <= 0)
{
//
// Handle failed writes here
//
if(!BIO_should_retry(bio))
{
// Not worth implementing, but worth knowing.
}
//
// -> Let us know about the failed writes
//
printf("Failed write\n");
}
//
// Variables used to read the response from the server
//
int size;
char buf[1024];
//
// Read the response message
//
for(;;)
{
//
// Get chunks of the response 1023 at the time.
//
size = BIO_read(bio, buf, 1023);
//
// If no more data, then exit the loop
//
if(size <= 0)
{
break;
}
//
// Terminate the string with a 0, to let know C when the string
// ends.
//
buf[size] = 0;
//
// -> Print out the response
//
printf("%s", buf);
}
//
// Clean after ourselves
//
BIO_free_all(bio);
SSL_CTX_free(ctx);
return 0;
}
上面的代码将详细说明如何与远程服务器建立TLS连接。
重要说明：此代码不检查公钥是否由有效授权机构签名。意思是我不使用根证书进行验证。不要忘记执行此检查，否则您不知道您是否正在连接正确的网站
当涉及到请求本身时。它只不过是手工编写HTTP请求。
您还可以在此link下找到解释如何在系统中安装openSSL，以及如何编译代码以便它使用secure library。
答案 3 :(得分：3)
处理添加。
添加了主机头。
添加了linux / windows支持，经过测试（XP，WIN7）
警告：错误：＆＃34;分段错误＆＃34;如果没有主机，路径或端口作为参数。
#include <stdio.h> /* printf, sprintf */
#include <stdlib.h> /* exit, atoi, malloc, free */
#include <unistd.h> /* read, write, close */
#include <string.h> /* memcpy, memset */
#ifdef __linux__
#include <sys/socket.h> /* socket, connect */
#include <netdb.h> /* struct hostent, gethostbyname */
#include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
#elif _WIN32
#include <winsock2.h>
#include <ws2tcpip.h>
#include <windows.h>
#pragma comment(lib,"ws2_32.lib") //Winsock Library
#else
#endif
void error(const char *msg) { perror(msg); exit(0); }
int main(int argc,char *argv[])
{
int i;
struct hostent *server;
struct sockaddr_in serv_addr;
int bytes, sent, received, total, message_size;
char *message, response[4096];
int portno = atoi(argv[2])>0?atoi(argv[2]):80;
char *host = strlen(argv[1])>0?argv[1]:"localhost";
char *path = strlen(argv[4])>0?argv[4]:"/";
if (argc < 5) { puts("Parameters: <host> <port> <method> <path> [<data> [<headers>]]"); exit(0); }
/* How big is the message? */
message_size=0;
if(!strcmp(argv[3],"GET"))
{
printf("Process 1\n");
message_size+=strlen("%s %s%s%s HTTP/1.0\r\nHost: %s\r\n"); /* method */
message_size+=strlen(argv[3]); /* path */
message_size+=strlen(path); /* headers */
if(argc>5)
message_size+=strlen(argv[5]); /* query string */
for(i=6;i<argc;i++) /* headers */
message_size+=strlen(argv[i])+strlen("\r\n");
message_size+=strlen("\r\n"); /* blank line */
}
else
{
printf("Process 2\n");
message_size+=strlen("%s %s HTTP/1.0\r\nHost: %s\r\n");
message_size+=strlen(argv[3]); /* method */
message_size+=strlen(path); /* path */
for(i=6;i<argc;i++) /* headers */
message_size+=strlen(argv[i])+strlen("\r\n");
if(argc>5)
message_size+=strlen("Content-Length: %d\r\n")+10; /* content length */
message_size+=strlen("\r\n"); /* blank line */
if(argc>5)
message_size+=strlen(argv[5]); /* body */
}
printf("Allocating...\n");
/* allocate space for the message */
message=malloc(message_size);
/* fill in the parameters */
if(!strcmp(argv[3],"GET"))
{
if(argc>5)
sprintf(message,"%s %s%s%s HTTP/1.0\r\nHost: %s\r\n",
strlen(argv[3])>0?argv[3]:"GET", /* method */
path, /* path */
strlen(argv[5])>0?"?":"", /* ? */
strlen(argv[5])>0?argv[5]:"",host); /* query string */
else
sprintf(message,"%s %s HTTP/1.0\r\nHost: %s\r\n",
strlen(argv[3])>0?argv[3]:"GET", /* method */
path,host); /* path */
for(i=6;i<argc;i++) /* headers */
{strcat(message,argv[i]);strcat(message,"\r\n");}
strcat(message,"\r\n"); /* blank line */
}
else
{
sprintf(message,"%s %s HTTP/1.0\r\nHost: %s\r\n",
strlen(argv[3])>0?argv[3]:"POST", /* method */
path,host); /* path */
for(i=6;i<argc;i++) /* headers */
{strcat(message,argv[i]);strcat(message,"\r\n");}
if(argc>5)
sprintf(message+strlen(message),"Content-Length: %d\r\n",(int)strlen(argv[5]));
strcat(message,"\r\n"); /* blank line */
if(argc>5)
strcat(message,argv[5]); /* body */
}
printf("Processed\n");
/* What are we going to send? */
printf("Request:\n%s\n",message);
/* lookup the ip address */
total = strlen(message);
/* create the socket */
#ifdef _WIN32
WSADATA wsa;
SOCKET s;
printf("\nInitialising Winsock...");
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0)
{
printf("Failed. Error Code : %d",WSAGetLastError());
return 1;
}
printf("Initialised.\n");
//Create a socket
if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET)
{
printf("Could not create socket : %d" , WSAGetLastError());
}
printf("Socket created.\n");
server = gethostbyname(host);
serv_addr.sin_addr.s_addr = inet_addr(server->h_addr);
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
memset(&serv_addr,0,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
//Connect to remote server
if (connect(s , (struct sockaddr *)&serv_addr , sizeof(serv_addr)) < 0)
{
printf("connect failed with error code : %d" , WSAGetLastError());
return 1;
}
puts("Connected");
if( send(s , message , strlen(message) , 0) < 0)
{
printf("Send failed with error code : %d" , WSAGetLastError());
return 1;
}
puts("Data Send\n");
//Receive a reply from the server
if((received = recv(s , response , 2000 , 0)) == SOCKET_ERROR)
{
printf("recv failed with error code : %d" , WSAGetLastError());
}
puts("Reply received\n");
//Add a NULL terminating character to make it a proper string before printing
response[received] = '\0';
puts(response);
closesocket(s);
WSACleanup();
#endif
#ifdef __linux__
int sockfd;
server = gethostbyname(host);
if (server == NULL) error("ERROR, no such host");
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) error("ERROR opening socket");
/* fill in the structure */
memset(&serv_addr,0,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
memcpy(&serv_addr.sin_addr.s_addr,server->h_addr,server->h_length);
/* connect the socket */
if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
/* send the request */
sent = 0;
do {
bytes = write(sockfd,message+sent,total-sent);
if (bytes < 0)
error("ERROR writing message to socket");
if (bytes == 0)
break;
sent+=bytes;
} while (sent < total);
/* receive the response */
memset(response, 0, sizeof(response));
total = sizeof(response)-1;
received = 0;
printf("Response: \n");
do {
printf("%s", response);
memset(response, 0, sizeof(response));
bytes = recv(sockfd, response, 1024, 0);
if (bytes < 0)
printf("ERROR reading response from socket");
if (bytes == 0)
break;
received+=bytes;
} while (1);
if (received == total)
error("ERROR storing complete response from socket");
/* close the socket */
close(sockfd);
#endif
free(message);
return 0;
}