http-client-c

A quick and dirty HTTP client library in and for C. The intention of http-client-c is to write an easy-to-use HTTP client in and for C. Usage should be easy without hassle but still advanced and easy to control. http-client-c is almost fully comliant with the HTTP 1.1 standards. http-client-c's code has been optimized to compile perfectly with all known C and C++ compilers. Altough the code is written in C, it can be used in C++ code as well.

Basic Usage

#include"http/client.h"http_request*request=http_request_new();
http_request_option(request, HTTP_OPTION_URL, argv[1], 0);
// http_request_option(request, HTTP_OPTION_METHOD, "POST");// http_request_option(request, HTTP_OPTION_BODY, "a=1&b=2");http_request_option(request, HTTP_OPTION_REQUEST_TIMEOUT, "5", 0);
http_request_option(request, HTTP_OPTION_REQUEST_HEADER_CALLBACK, request_header_cb, 0);
http_request_option(request, HTTP_OPTION_RESPONSE_HEADER_CALLBACK, response_header_cb, 0);
http_request_option(request, HTTP_OPTION_RESPONSE_BODY_CALLBACK, response_body_cb, 0);
// add an HTTP header, replace existing http_request_header_set(request, "User-Agent", "Firefox 12");
// http_request_header_set(request, "Authorization", "Bearer <secret>");// add an HTTP header, keep existinghttp_request_header_add(request, "Accept-Language", "en-US;q=0.6,en;q=0.4");
// execute the requesthttp_response*response=http_request_exec(request);
http_request_free(request);
http_response_free(response);

http_request

the request structure.

typedefstructhttp_request {
http_header*headers;
size_tbody_len;
char*body;
char*request_uri;
intmax_redirect;
char*method;
http_header_cb_ptr*request_header_cb;
http_header_cb_ptr*response_header_cb;
http_response_body_cb_ptr*response_body_cb;
structtimeval*request_timeout;
} http_request;

create a request struct pointer.

http_request*request=http_request_new();

configure the request options

// http_request *hreq - the request struct pointer// http_option option - the option to configure// const void *val - option payload// size_t len - the payload length, only needed if the payload is a binary string, otherwise pass 0// void http_request_option(http_request *hreq, http_option option, const void *val, size_t len)http_request_option(request, HTTP_OPTION_URL, argv[1], 0);
// http_request_option(request, HTTP_OPTION_METHOD, "POST");// http_request_option(request, HTTP_OPTION_BODY, "a=1&b=2");http_request_option(request, HTTP_OPTION_REQUEST_TIMEOUT, "5", 0);
http_request_option(request, HTTP_OPTION_REQUEST_HEADER_CALLBACK, request_header_cb, 0);
http_request_option(request, HTTP_OPTION_RESPONSE_HEADER_CALLBACK, response_header_cb, 0);
http_request_option(request, HTTP_OPTION_RESPONSE_BODY_CALLBACK, response_body_cb, 0);
http_request_header_set(request, "User-Agent", "Firefox 12");
// http_request_header_set(request, "Authorization", "Bearer <secret>");http_request_header_add(request, "Accept-Language", "en-US;q=0.6,en;q=0.4");

http option flags

• HTTP_OPTION_URL: pass the url
• HTTP_OPTION_HEADER: pass an HTTP header as a struct http_header pointer
• HTTP_OPTION_BODY: pass the request payload
• HTTP_OPTION_METHOD: pass the HTTP method
• HTTP_OPTION_REQUEST_TIMEOUT: set the request timeout as a numeric string
• HTTP_OPTION_REQUEST_HEADER_CALLBACK: pass a request header callback (see ./test/main.c for an example)
• HTTP_OPTION_RESPONSE_HEADER_CALLBACK: pass a response header callback (see ./test/main.c for an example)
• HTTP_OPTION_RESPONSE_BODY_CALLBACK: pass a response body callback (see ./test/main.c for an example)

http_response

http_response is a structure that is returned by http_request_exec method, it contains information about the response. Please note that this function returns a pointer to an instance of http_response. The structure is as following:

typedefstructhttp_response {
http_header*headers;
char*body;
size_tbody_len;
char*redirect_uri;
intredirect_count;
intstatus_code;
char*status_text;
} http_response;

*redirect_ui

The last redirected url.

*redirect_count

the HTTP redirect count

*body

The response body. always NULL if you set a response body callback

body_len

the response body length

status_code

the response HTTP status code

*status_text

This returns the text associated with the status code. For status code 200, OK will be returned.

*headers

response HTTP headers as struct http_header pointer.

HTTP response callback

Provide an HTTP response body callback to handle large HTTP response payload efficiently. this will avoid allocating memory to hold the response.

full example

#include"http/client.h"FILE*fp;
/** * response header callback * @param headers */voidresponse_header_cb(http_header*headers) {
http_header*header=headers;
fprintf(stderr, "headers received:\n");
char*printed=http_header_print(headers);
fprintf(stderr, "%s\r\n", printed);
fwrite(printed, strlen(printed), 1, fp);
fwrite("\r\n", 2, 1, fp);
free(printed);
}
/** * request header callback * @param headers */voidrequest_header_cb(http_header*headers) {
http_header*header=headers;
fprintf(stderr, "headers sent:\n");
char*printed=http_header_print(headers);
fprintf(stderr, "%s\r\n", printed);
fwrite(printed, strlen(printed), 1, fp);
fwrite("\r\n", 2, 1, fp);
free(printed);
}
/** * response body callback * @param chunk * @param chunk_len * @param headers */voidresponse_body_cb(constchar*chunk, size_tchunk_len, http_header*headers) {
if (chunk_len>0) {
fwrite(chunk, 1, chunk_len, fp);
http_header*content_type=http_header_get(headers, "Content-Type");
// if text content, dump to stderrif (content_type!=NULL&&strstr(content_type->value, "text/") !=NULL) {
fwrite(chunk, chunk_len, 1, stderr);
}
http_header_free(content_type);
}
}
intmain(intargc, char*argv[]) {
if (argc <= 2) {
fprintf(stderr, "Usage: \n$ %s URL DEST_FILE\n", argv[0]);
exit(1);
}
char*filename=argc>2 ? argv[2] : "";
fprintf(stderr, "opening %s ...\n", filename);
http_request*request=http_request_new();
http_request_option(request, HTTP_OPTION_URL, argv[1], 0);
// http_request_option(request, HTTP_OPTION_METHOD, "POST");// http_request_option(request, HTTP_OPTION_BODY, "a=1&b=2");http_request_option(request, HTTP_OPTION_REQUEST_TIMEOUT, "5", 0);
http_request_option(request, HTTP_OPTION_REQUEST_HEADER_CALLBACK, request_header_cb, 0);
http_request_option(request, HTTP_OPTION_RESPONSE_HEADER_CALLBACK, response_header_cb, 0);
http_request_option(request, HTTP_OPTION_RESPONSE_BODY_CALLBACK, response_body_cb, 0);
http_request_header_set(request, "User-Agent", "Firevox");
// http_request_header_set(request, "Authorization", "Bearer <secret>");http_request_header_add(request, "Accept-Language", "en-US;q=0.6,en;q=0.4");
fp=fopen(filename, "wb");
http_response*response=http_request_exec(request);
fclose(fp);
http_request_free(request);
http_response_free(response);
return0;
}