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In c programming, raw socket for http is worked well without using curl, but we will target

Confirm Author: test test replied at 2026-06-18 13:57:32    

Be Reminded to set:

Confirm Expert: Wilson Edwards replied at 2026-06-18 02:36:56    

sudo dnf install openssl-devel

Confirm Author: test test replied at 2026-06-17 10:16:09    

You need install openssl

Confirm Expert: rcschroeder replied at 2026-06-17 10:08:41    

To set up a raw socket in C to communicate with an HTTPS server and receive a 302 redirect response, you'll need to follow these steps:

**Step 1: Create a raw socket**

You can use the `socket()` function from the Linux kernel's network programming API (syscalls) to create a raw socket. The socket type is set using the `AF_INET` address family and the `SOCK_RAW` socket type.

```c
#include <sys/socket.h>

int sock = socket(AF_INET, SOCK_RAW, IPPROTO_TCP);
```

**Step 2: Set up the socket options**

To receive HTTPS traffic, you need to set up the socket options to intercept incoming HTTP requests. You'll use the `SETsockopt()` function with the `IPCV4` option to enable IPv4 and the `SO_RCVBUF` option to set the receive buffer size.

```c
int optval = 1;
size_t optlen = sizeof(optval);

setsockopt(sock, IPV4, SO_RCVBUF, &optval, optlen);
```

**Step 3: Set up the SSL/TLS layer**

To establish a secure connection to an HTTPS server, you'll need to set up an SSL/TLS layer. You can use the OpenSSL library to create a TLS client context.

```c
#include <openssl/ssl.h>
#include <openssl/err.h>

SSL_CTX *ctx;
```

**Step 4: Connect to the HTTPS server**

Using the established socket and SSL/TLS context, you'll connect to the HTTPS server. The `connect()` function takes the hostname or IP address of the server as an argument.

```c
int err = SSL_connect(ctx);
if (err != 1) {
// Handle connection error
}
```

**Step 5: Receive and process the response**

Once connected, you can receive data from the HTTPS server using the `recv()` function. Since the server returns a 302 redirect response, you'll need to parse the HTTP headers to extract the new URL.

```c
char buffer[1024];
int bytesReceived = recv(sock, buffer, 1024, 0);
if (bytesReceived < 0) {
// Handle receive error
}

// Parse HTTP headers to extract new URL
```

**Example Code**

Here's a simplified example code that demonstrates the above steps:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <openssl/ssl.h>

int main() {
// Create raw socket
int sock = socket(AF_INET, SOCK_RAW, IPPROTO_TCP);

// Set up socket options
int optval = 1;
size_t optlen = sizeof(optval);
setsockopt(sock, IPV4, SO_RCVBUF, &optval, optlen);

// Create SSL/TLS context
SSL_CTX *ctx = SSL_CTX_new(TLS_client_method());
SSL_load_error_strings();
OpenSSL_add_all_algorithms();

// Connect to HTTPS server
char hostname[] = "example.com";
int err = SSL_connect(ctx);
if (err != 1) {
printf("Connection error: %s", SSL_get_error(ctx, err));
return -1;
}

// Receive response from server
char buffer[1024];
int bytesReceived = recv(sock, buffer, 1024, 0);
if (bytesReceived < 0) {
printf("Receive error: %s", strerror(errno));
return -1;
}

// Parse HTTP headers to extract new URL
char* LocationHeader = strstr(buffer, "Location:");
if (LocationHeader != NULL) {
printf("New URL: %s", LocationHeader + 9);
} else {
printf("No Location header found");
}

return 0;
}
```
Note that this example assumes a simplified scenario where the server returns a 302 redirect response with a `Location` header. You'll need to modify the code to handle more complex scenarios.

Also, keep in mind that raw sockets and SSL/TLS interactions are complex topics, and there are many security considerations and potential pitfalls to be aware of when working with them.