A C# script that contains helper extension methods for the HttpRequestMessage class, to simplify Azure Function development.

Http.csx

#r "System.Management.Automation"
#r "System.Web"

using System.Net;
using System.Net.Http;

public static string Query(this HttpRequestMessage request, string name, string defaultValue = null) {
    var pairs = request.GetQueryNameValuePairs().Where(q => String.Equals(q.Key, name, StringComparison.OrdinalIgnoreCase));
    if (pairs.Any()) { return pairs.First().Value; }
    return defaultValue;
}

public static T Query<T>(this HttpRequestMessage request, string name, T defaultValue = default(T)) {
    string valueAsString = Query(request, name);
    if (!String.IsNullOrWhiteSpace(valueAsString)) {
        // Leverages PowerShell's flexible type conversion semantics.
        // For example, makes it trivial to return a parsed IPAddress from a query string parameter.
        return (T)System.Management.Automation.LanguagePrimitives.ConvertTo(valueAsString, typeof(T));
    }
    return defaultValue;
}

public static string Header(this HttpRequestMessage request, string name, string defaultValue = null) {
    var pairs = request.Headers.Where(q => String.Equals(q.Key, name, StringComparison.OrdinalIgnoreCase));
    if (pairs.Any()) { return pairs.First().Value.FirstOrDefault(); } // what a disgusting api
    return defaultValue;    
}

public static T Property<T>(this HttpRequestMessage request, string name, T defaultValue = default(T)) {
    object value;
    if (request.Properties.TryGetValue(name, out value)) {
        return (T)value;
    }
    return defaultValue;    
}

public static async Task<dynamic> Body(this HttpRequestMessage request) {
    return await request.Content.ReadAsAsync<object>();
}

public static async Task<T> Body<T>(this HttpRequestMessage request) {
    return await request.Content.ReadAsAsync<T>();
}

public static System.Net.IPAddress ClientIP(this HttpRequestMessage request) {

    // First, prefer the X-Forwarded-For header
    string valueAsString = Header(request, "X-Forwarded-For");
    if (valueAsString != null) {
        valueAsString = valueAsString.Split(':',',')[0];
    }
    else {
        // If there's no header indicating a proxy forwarded request,
        // revert to the actual IP address of the client.
        var httpContext = Property<System.Web.HttpContextBase>(request, "MS_HttpContext");
        if (httpContext != null) {
            valueAsString = httpContext.Request.UserHostAddress;
        }
    }

    IPAddress addr;
    if (IPAddress.TryParse(valueAsString, out addr)) {
        return addr;
    }

    return null;

}

public static void Trace(this HttpRequestMessage request, TraceWriter log) {

    log.Info("HttpRequestMessage Trace");
    
    log.Info(" ");
    log.Info($"Method    : {request.Method}");
    log.Info($"URI       : {request.RequestUri}");
    log.Info($"Client IP : {ClientIP(request)}");
    
    log.Info(" ");
    log.Info("- HEADERS");
    foreach (var pair in request.Headers) {
        log.Info($"{pair.Key} : {pair.Value.FirstOrDefault()}");
    }

    log.Info(" ");
    log.Info("- PROPERTIES");
    foreach (var pair in request.Properties) {
        log.Info($"{pair.Key} : {pair.Value}");
    }

    log.Info(" ");

}