OpenSSL Example - Github API

openssl_example.c

/*
 * This is free and unencumbered software released into the public domain.
 * gcc -o openssl_example.c openssl_example -lssl -lcrypto
 */
#include <string.h>
#include <stdio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/bio.h>

#define USERNAME "jnchi"

int main()
{
    BIO* bio;
    SSL_CTX* ctx;

    char buf[2048];
    char response_buf[2048];
    char write_buf[2048];
    int size, start, end;

    strcpy(response_buf, " ");

    SSL_library_init();

    ctx = SSL_CTX_new(SSLv23_client_method());

    if (ctx == NULL)
        printf("ctx is null\n");

    bio = BIO_new_ssl_connect(ctx);
    BIO_set_conn_hostname(bio, "api.github.com:443");

    if(BIO_do_connect(bio) <= 0)
    {
        printf("Failed connection\n");
        return 1;
    }
    else
    {
        printf("Connected\n");
    }

    /* https://developer.github.com/v3/users/#get-a-single-user */
    strcpy(write_buf, "GET /users/");
    strcat(write_buf, USERNAME);
    strcat(write_buf, " HTTP/1.1\r\n");
    strcat(write_buf, "User-Agent: openssl_example/1.0 \r\n");
    strcat(write_buf, "Host: api.github.com\r\n");
    strcat(write_buf, "Connection: close \r\n");
    strcat(write_buf, "\r\n");

    printf("write_buf: %s\n", write_buf);

    if(BIO_write(bio, write_buf, strlen(write_buf)) <= 0)
    {
        if(!BIO_should_retry(bio))
        {
            printf("Do retry\n");
        }

        printf("Failed write\n");
    }
   printf("passed BIO_write\n");

    for (;;)
    {
        size = BIO_read(bio, buf, sizeof(buf));
        printf("size %d\n", size);

        if(size <= 0 )
        {
            break;
        }
        buf[size] = 0;
        strcat(response_buf, buf);
        printf("buf %s\n", buf);
    }

    printf("passed BIO_read\n");

    BIO_free_all(bio);
    SSL_CTX_free(ctx);

    printf("passed BIO_free_all and SSL_CTX_free\n");

    /* TODO: Extract JSON from response */
    printf("response_buf %s\n", response_buf);
    printf("sizeof(response_buf) %ld\n", sizeof(response_buf));
    return 0;
}